WO2020066034A1 - Power conversion apparatus, motor drive apparatus, and air conditioner - Google Patents

Power conversion apparatus, motor drive apparatus, and air conditioner Download PDF

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Publication number
WO2020066034A1
WO2020066034A1 PCT/JP2018/036611 JP2018036611W WO2020066034A1 WO 2020066034 A1 WO2020066034 A1 WO 2020066034A1 JP 2018036611 W JP2018036611 W JP 2018036611W WO 2020066034 A1 WO2020066034 A1 WO 2020066034A1
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WIPO (PCT)
Prior art keywords
current
power supply
value
control unit
switching element
Prior art date
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PCT/JP2018/036611
Other languages
French (fr)
Japanese (ja)
Inventor
啓介 植村
智 一木
卓也 下麥
有澤 浩一
憲嗣 岩崎
Original Assignee
三菱電機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to JP2020547898A priority Critical patent/JP6987268B2/en
Priority to PCT/JP2018/036611 priority patent/WO2020066034A1/en
Publication of WO2020066034A1 publication Critical patent/WO2020066034A1/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/88Electrical aspects, e.g. circuits
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal

Definitions

  • the present invention relates to a power conversion device that converts AC power into DC power, a motor drive device, and an air conditioner.
  • the power conversion device that converts supplied AC power into DC power and outputs the converted power by using a bridge circuit composed of switching elements.
  • the power conversion device can perform a boosting operation of boosting the voltage of AC power and a synchronous rectification operation of rectifying AC power by turning on and off the switching element.
  • Patent Literature 1 discloses that a power conversion device sets two switching elements of four switching elements according to a polarity of a voltage according to a voltage of AC power supplied from an AC power supply and a current flowing to the AC power supply. There is disclosed a technique for controlling the other two switching elements in accordance with the polarity of the current.
  • the power conversion device described in Patent Document 1 when the polarity of the current is positive, one of the two switching elements controlled according to the polarity of the current when the absolute value of the current value becomes equal to or greater than the determination value a. Is turned on, and when the absolute value of the current value becomes equal to or smaller than the judgment value b smaller than the judgment value a, one of the switching elements is turned off.
  • the power conversion device described in Patent Document 1 when the polarity of the current is negative, of the two switching elements controlled according to the polarity of the current, when the absolute value of the current value is equal to or greater than the determination value a, the other switching element is controlled. The switching element is turned on, and when the absolute value of the current value becomes equal to or smaller than the determination value b, the other switching element is turned off.
  • the power conversion device described in Patent Literature 1 uses two determination values to increase the on-period of the switching element and improve the efficiency.
  • the power conversion device described in Patent Literature 1 turns off the switching element when the absolute value of the current value becomes equal to or smaller than the determination value b smaller than the determination value a. For this reason, the power conversion device described in Patent Literature 1 turns off after the current value becomes zero if the process of turning off the switching element is delayed depending on the setting of the determination value b. There is a problem that a reverse current may flow from the voltage side to the AC power supply side.
  • the present invention has been made in view of the above, and an object of the present invention is to provide a power converter capable of improving efficiency in synchronous rectification operation while suppressing generation of a backflow current.
  • a power converter has a reactor having a first end and a second end, the first end being connected to an AC power supply, A bridge circuit that is connected to the second end of the reactor and includes at least one or more switching elements, converts an AC voltage output from an AC power supply into a DC voltage, and a current detection unit that detects a current of the AC power supply, A control unit that controls on / off of the switching element in accordance with the current value detected by the current detection unit. The control unit performs on / off control using a past current value detected by the current detection unit.
  • the power converter according to the present invention has an effect that the efficiency in the synchronous rectification operation can be improved while suppressing the generation of the backflow current.
  • FIG. 2 is a diagram illustrating a configuration example of a power conversion device according to the first embodiment.
  • Schematic sectional view showing a schematic structure of a MOSFET 1 is a first diagram illustrating a path of a current flowing through a power conversion device according to a first embodiment when an absolute value of a power supply current is larger than a current threshold value and a power supply voltage polarity is positive.
  • FIG. 1 is a first diagram illustrating a path of a current flowing through the power conversion device according to the first embodiment when the absolute value of the power supply current is larger than a current threshold value and the power supply voltage polarity is negative.
  • FIG. 5 is a diagram showing a process in which the control unit of the power conversion device according to the first embodiment calculates a predicted value of a current value detected next by the power supply current detection unit.
  • FIG. 5 is a flowchart showing processing performed by the control unit of the power conversion device according to the first embodiment for a switching element that controls on / off in accordance with the polarity of the power supply current.
  • FIG. 3 is a diagram illustrating an example of a hardware configuration that realizes a control unit included in the power conversion device according to the first embodiment. The figure which shows the timing which the control part of the electric power converter concerning Embodiment 2 turns on a switching element.
  • FIG. 7 is a diagram illustrating a configuration example of a motor drive device according to a third embodiment. The figure which shows the example of a structure of the air conditioner which concerns on Embodiment 4.
  • FIG. 1 is a diagram showing a configuration example of a power conversion device 100 according to Embodiment 1 of the present invention.
  • the power conversion device 100 is a power supply device having an AC / DC conversion function of converting AC power supplied from the AC power supply 1 to DC power and applying the DC power to the load 50 using the bridge circuit 3.
  • the power conversion device 100 includes a reactor 2, a bridge circuit 3, a smoothing capacitor 4, a power supply voltage detector 5, a power supply current detector 6, a bus voltage detector 7, a controller, 10 is provided.
  • Reactor 2 has a first end and a second end, and the first end is connected to AC power supply 1.
  • the bridge circuit 3 is a circuit including two arms in which two switching elements each having a diode connected in parallel are connected in series, and two arms connected in parallel.
  • the bridge circuit 3 includes a first arm 31 that is a first circuit and a second arm 32 that is a second circuit.
  • the first arm 31 includes a switching element 311 and a switching element 312 connected in series.
  • a parasitic diode 311a is formed in the switching element 311.
  • the parasitic diode 311a is connected in parallel between the drain and the source of the switching element 311.
  • a parasitic diode 312a is formed in the switching element 312.
  • the parasitic diode 312a is connected in parallel between the drain and the source of the switching element 312.
  • Each of the parasitic diodes 311a and 312a is a diode used as a freewheeling diode.
  • the second arm 32 includes a switching element 321 and a switching element 322 connected in series.
  • the second arm 32 is connected in parallel to the first arm 31.
  • the switching element 321 is formed with a parasitic diode 321a.
  • the parasitic diode 321a is connected in parallel between the drain and the source of the switching element 321.
  • the switching element 322 is formed with a parasitic diode 322a.
  • the parasitic diode 322a is connected in parallel between the drain and the source of the switching element 322.
  • Each of the parasitic diodes 321a and 322a is a diode used as a freewheeling diode.
  • the power conversion device 100 includes a first wiring 501 and a second wiring 502, each of which is connected to the AC power supply 1, and a reactor 2 arranged on the first wiring 501.
  • the first arm 31 includes a switching element 311 as a first switching element, a switching element 312 as a second switching element, and a third wiring 503 having a first connection point 506.
  • the switching element 311 and the switching element 312 are connected in series by a third wiring 503.
  • the first wiring 501 is connected to the first connection point 506.
  • the first connection point 506 is connected to the AC power supply 1 via the first wiring 501 and the reactor 2.
  • the first connection point 506 is connected to the second end of the reactor 2.
  • the second arm 32 includes a switching element 321 as a third switching element, a switching element 322 as a fourth switching element, and a fourth wiring 504 including a second connection point 508. 321 and the switching element 322 are connected in series by the fourth wiring 504.
  • the second wiring 502 is connected to the second connection point 508.
  • Second connection point 508 is connected to AC power supply 1 via second wiring 502.
  • the bridge circuit 3 may include at least one or more switching elements, and may convert an AC voltage output from the AC power supply 1 into a DC voltage.
  • the smoothing capacitor 4 is a capacitor connected in parallel to the bridge circuit 3, more specifically, to the second arm 32.
  • one end of the switching element 311 is connected to the positive side of the smoothing capacitor 4
  • the other end of the switching element 311 is connected to one end of the switching element 312, and the other end of the switching element 312 is connected to the negative side of the smoothing capacitor 4. Connected to the side.
  • the switching elements 311, 312, 321, 322 are composed of MOSFETs.
  • the switching elements 311, 312, 321, and 322 are formed of a wide band gap (WBG) semiconductor such as gallium nitride (GaN), silicon carbide (Silicon Carbide: SiC), diamond, or aluminum nitride.
  • WBG wide band gap
  • MOSFETs can be used.
  • the control unit 10 drives the switching pulses 311, 312, 321, and 322 of the bridge circuit 3 based on signals output from the power supply voltage detection unit 5, the power supply current detection unit 6, and the bus voltage detection unit 7.
  • the power supply voltage detector 5 is a voltage detector that detects a power supply voltage Vs, which is a voltage value of an output voltage of the AC power supply 1, and outputs an electric signal indicating a detection result to the controller 10.
  • the power supply current detection unit 6 is a current detection unit that detects the power supply current Is, which is the current value of the current output from the AC power supply 1, and outputs an electric signal indicating the detection result to the control unit 10.
  • the power supply current Is is a current value of a current flowing between the AC power supply 1 and the bridge circuit 3.
  • the bus voltage detection unit 7 is a voltage detection unit that detects the bus voltage Vdc and outputs an electric signal indicating the detection result to the control unit 10.
  • the bus voltage Vdc is a voltage obtained by smoothing the output voltage of the bridge circuit 3 with the smoothing capacitor 4.
  • the control unit 10 controls ON / OFF of the switching elements 311, 312, 321, 322 according to the power supply voltage Vs, the power supply current Is, and the bus voltage Vdc.
  • the control unit 10 may control on / off of the switching elements 311, 312, 321, 322 by using at least one of the power supply voltage Vs, the power supply current Is, and the bus voltage Vdc.
  • switching elements 311 and 321 connected to the positive side of AC power supply 1, that is, the positive terminal of AC power supply 1, may be referred to as upper switching elements.
  • switching elements 312 and 322 connected to the negative side of AC power supply 1, that is, the negative terminal of AC power supply 1, may be referred to as lower switching elements.
  • the upper switching element and the lower switching element operate complementarily. That is, when one of the upper switching element and the lower switching element is on, the other is off.
  • the switching elements 311 and 312 constituting the first arm 31 are driven by a PWM (Pulse Width Modulation) signal which is a drive signal generated by the control unit 10 as described later.
  • PWM Pulse Width Modulation
  • the operation of turning on or off the switching elements 311 and 312 according to the PWM signal is hereinafter also referred to as a switching operation.
  • a short circuit of the smoothing capacitor 4 is referred to as a capacitor short circuit.
  • the capacitor short-circuit is a state in which the energy stored in the smoothing capacitor 4 is released and the current is regenerated in the AC power supply 1.
  • the switching elements 321 and 322 constituting the second arm 32 are turned on or off by a drive signal generated by the control unit 10.
  • the switching elements 321 and 322 are basically turned on or off according to the power supply voltage polarity that is the polarity of the voltage output from the AC power supply 1. Specifically, when the power supply voltage polarity is positive, the switching element 322 is on and the switching element 321 is off, and when the power supply voltage polarity is negative, the switching element 321 is on and Element 322 is off.
  • the drive signal for controlling the on / off of the switching elements 321 and 322 and the PWM signal for controlling the on / off of the switching elements 311 and 312 are indicated by arrows from the control unit 10 to the bridge circuit 3.
  • FIG. 2 is a schematic sectional view showing a schematic structure of the MOSFET.
  • FIG. 2 illustrates an n-type MOSFET.
  • a p-type semiconductor substrate 600 is used as shown in FIG.
  • a source electrode S, a drain electrode D, and a gate electrode G are formed on the semiconductor substrate 600.
  • High-concentration impurities are ion-implanted into a portion in contact with the source electrode S and the drain electrode D to form an n-type region 601.
  • an oxide insulating film 602 is formed between a portion where the n-type region 601 is not formed and the gate electrode G. That is, the oxide insulating film 602 is interposed between the gate electrode G and the p-type region 603 in the semiconductor substrate 600.
  • the channel 604 is an n-type channel in the example of FIG.
  • FIG. 3 is a first diagram showing a path of a current flowing through power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is positive.
  • the power supply voltage polarity is positive
  • the switching element 311 and the switching element 322 are on
  • the switching element 312 and the switching element 321 are off.
  • current flows in the order of AC power supply 1, reactor 2, switching element 311, smoothing capacitor 4, switching element 322, and AC power supply 1.
  • the synchronous rectification operation is performed by causing the current not to flow through the parasitic diode 311a and the parasitic diode 322a but to flow through each channel of the switching element 311 and the switching element 322.
  • the switching elements that are turned on are indicated by circles. The same applies to the following drawings.
  • FIG. 4 is a first diagram illustrating a path of a current flowing in power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is negative.
  • the power supply voltage polarity is negative
  • the switching element 312 and the switching element 321 are on
  • the switching element 311 and the switching element 322 are off.
  • current flows in the order of the AC power supply 1, the switching element 321, the smoothing capacitor 4, the switching element 312, the reactor 2, and the AC power supply 1.
  • the synchronous rectification operation is performed by causing the current not to flow through the parasitic diode 321a and the parasitic diode 312a but to flow through each channel of the switching element 321 and the switching element 312.
  • FIG. 5 is a second diagram illustrating a path of a current flowing through power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is positive.
  • the power supply voltage polarity is positive
  • the switching element 312 and the switching element 322 are on
  • the switching element 311 and the switching element 321 are off.
  • a current flows in the order of the AC power supply 1, the reactor 2, the switching element 312, the switching element 322, and the AC power supply 1, and a power supply short-circuit path that does not pass through the smoothing capacitor 4 is formed.
  • a current does not flow through the parasitic diode 312a and the parasitic diode 322a, but a current flows through each channel of the switching element 312 and the switching element 322, thereby forming a power supply short-circuit path. .
  • FIG. 6 is a second diagram illustrating a path of a current flowing through power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is negative.
  • the power supply voltage polarity is negative, the switching element 311 and the switching element 321 are on, and the switching element 312 and the switching element 322 are off.
  • current flows in the order of the AC power supply 1, the switching element 321, the switching element 311, the reactor 2, and the AC power supply 1, and a power supply short-circuit path that does not pass through the smoothing capacitor 4 is formed.
  • a current does not flow through the parasitic diode 311a and the parasitic diode 321a, but a current flows through each channel of the switching element 311 and the switching element 321, thereby forming a power supply short-circuit path.
  • the control unit 10 can control the values of the power supply current Is and the bus voltage Vdc by controlling the switching of the current paths described above.
  • the power converter 100 continuously switches between the load power supply mode shown in FIG. 3 and the power supply short-circuit mode shown in FIG. 5 when the power supply voltage polarity is positive, and the load shown in FIG. 4 when the power supply voltage polarity is negative.
  • the control unit 10 sets the switching frequency of the switching elements 311 and 312 performing the switching operation by PWM higher than the switching frequency of the switching elements 321 and 322 performing the switching operation according to the polarity of the power supply voltage Vs.
  • the on / off of the switching elements 311, 312, 321, 322 is controlled.
  • the switching elements 311, 312, 321 and 322 when they are not distinguished, they may be simply referred to as switching elements.
  • the parasitic diodes 311a, 312a, 321a, and 322a are not distinguished, they may be simply referred to as parasitic diodes.
  • FIG. 7 is a diagram showing the timing at which the control unit 10 turns on the switching element in the power conversion device 100 according to the first embodiment.
  • the horizontal axis is time.
  • Vs is the power supply voltage Vs detected by the power supply voltage detector 5
  • Is is the power supply current Is detected by the power supply current detector 6.
  • FIG. 7 shows that the switching elements 311 and 312 are current-synchronous switching elements whose on and off are controlled in accordance with the polarity of the power supply current Is, and the switching elements 321 and 322 correspond to the polarity of the power supply voltage Vs.
  • FIG. 7 Indicates that the switching element is a voltage-synchronized switching element whose on / off is controlled.
  • Ith represents a current threshold.
  • FIG. 7 illustrates one cycle of the AC power output from the AC power supply 1, the control unit 10 performs control similar to the control illustrated in FIG. 7 in other cycles.
  • the control unit 10 When the power supply voltage polarity is positive, the control unit 10 turns on the switching element 322 and turns off the switching element 321. When the power supply voltage polarity is negative, the control unit 10 turns on the switching element 321 and turns off the switching element 322.
  • the timing at which the switching element 322 turns from on to off and the timing at which the switching element 321 turns from off to on are the same, but the present invention is not limited to this.
  • the control unit 10 may provide a dead time during which both the switching elements 321 and 322 are turned off between the timing when the switching element 322 is turned off from on and the timing when the switching element 321 is turned on from off.
  • the control unit 10 provides a dead time during which both the switching elements 321 and 322 are turned off between the timing when the switching element 321 is turned off from on and the timing when the switching element 322 is turned on from off. Is also good.
  • the control unit 10 turns on the switching element 311 when the power supply voltage polarity is positive and the absolute value of the power supply current Is becomes equal to or greater than the current threshold value Ith. Thereafter, when the absolute value of the power supply current Is becomes smaller and the absolute value of the power supply current Is becomes smaller than the current threshold value Ith, the control unit 10 turns off the switching element 311. When the power supply voltage polarity is negative and the absolute value of the power supply current Is becomes equal to or greater than the current threshold Ith, the control unit 10 turns on the switching element 312. Thereafter, when the absolute value of the power supply current Is decreases and the absolute value of the power supply current Is becomes smaller than the current threshold value Ith, the control unit 10 turns off the switching element 312.
  • control unit 10 controls the switching elements 311 and 321 of the upper switching element so as not to be turned on at the same time. Control is performed so that the switch 312 and the switching element 322 are not turned on at the same time. Thereby, control unit 10 can prevent a capacitor short circuit in power conversion device 100.
  • control unit 10 determines the first current value which is the current value detected last time by power supply current detection unit 6 and the second current value which is the current value detected by power supply current detection unit 6 this time. Using the value, the predicted value of the current value detected next by the power supply current detection unit 6 is calculated.
  • the first current value detected last time is the current value detected in the past by the power supply current detection unit 6, and the second current value detected this time is the current value detected newly by the power supply current detection unit 6. Value.
  • the control unit 10 controls on / off of the switching elements 311 and 312 according to the calculated predicted value. As described above, the control unit 10 controls on / off of the switching elements 311 and 312 using the past current value detected by the power supply current detection unit 6.
  • FIG. 8 is a diagram illustrating a process in which the control unit 10 of the power conversion device 100 according to Embodiment 1 calculates a predicted value of a current value detected next by the power supply current detection unit 6.
  • FIG. 8 shows the actual power supply current flowing through the power conversion device 100 and the power supply current Is detected by the power conversion device 100 with respect to the power supply current Is shown in FIG.
  • FIG. 8 shows a portion of the power supply current Is shown in FIG. 7 where the polarity of the power supply current Is is positive.
  • the horizontal axis represents time
  • the vertical axis represents current value.
  • Ith indicates a current threshold.
  • Id (n-1) is a current value detected by the power supply current detection unit 6 at the (n-1) th control timing, and corresponds to the above-described first current value.
  • Id (n) is a current value detected by the power supply current detection unit 6 at the time of the n-th control timing, and corresponds to the above-described second current value.
  • Ie (n) is obtained by the control unit 10 predicting the current value detected next by the power supply current detection unit 6 at the time of the n-th control timing, and corresponds to the above-described predicted value.
  • Ts is a cycle in which the power supply current detector 6 detects a current value, and is the above-described control cycle. In such a case, the control unit 10 can calculate the predicted value Ie (n) using the following equation (1).
  • Equation (1) ((Id (n) ⁇ Id (n ⁇ 1)) / Ts) is a linear approximation of the change in the power supply current Is during the period from the (n ⁇ 1) th control timing to the nth control timing. It is the inclination when doing.
  • the control unit 10 calculates a value calculated using the current value Id (n-1), the current value Id (n), and the control cycle Ts in which the power supply current detection unit 6 detects the current value, by using the current value Id (n). To calculate the predicted value Ie (n). Equation (1) can be modified as in the following equation (2).
  • control unit 10 can calculate the predicted value Ie (n) by adding the difference between the current value Id (n) and the current value Id (n-1) to the current value Id (n). it can.
  • control unit 10 may multiply a value calculated by the right side of Expression (1) or Expression (2) by a specified coefficient as the predicted value Ie (n). Thereby, the control unit 10 can cope with a case where the change of the power supply current Is is sharp.
  • FIG. 9 is a flowchart showing a process performed by the control unit 10 of the power converter 100 according to Embodiment 1 for the switching elements 311 and 312 that control on / off in accordance with the polarity of the power supply current Is.
  • the control unit 10 calculates a predicted value Ie (n) (Step S1).
  • the method of calculating the predicted value Ie (n) in the control unit 10 is as described above.
  • the control unit 10 compares the absolute value of the predicted value Ie (n) with the current threshold value Ith (Step S2).
  • Step S3: Yes the control unit 10 determines that the absolute value of the current value detected by the power supply current detection unit 6 is equal to or less than the current threshold value Ith. Then, among the switching elements controlled according to the polarity of the current, the switching element 311 that is turned on is turned off (step S4).
  • Step S3: No the control unit 10 determines that the absolute value of the current value detected by the power supply current detector 6 is larger than the current threshold Ith.
  • the switching element 311 which is turned on among the switching elements controlled in accordance with the polarity of the current is kept on (step S5).
  • the control unit 10 performs the same processing on the switching element 312 as described above.
  • the control cycle Ts is an interval at which the power supply current detector 6 detects a current value such that the predicted value Ie (n) calculated by the controller 10 satisfies ⁇ Ith ⁇ Ie (n) ⁇ Ith. .
  • the control unit 10 calculates the predicted value Ie (n) of the current value detected by the power supply current detection unit 6 so that when the absolute value of the predicted value Ie (n) becomes equal to or smaller than the current threshold value Ith,
  • the switching element can be turned off before the absolute value of the current value of the current flowing through the power converter 100 reaches the current threshold value Ith. That is, power conversion device 100 can prevent generation of a reverse current from smoothing capacitor 4 to AC power supply 1 due to a delay in turning off the switching element due to the control delay. Therefore, the user using the power converter 100 can set the current threshold value Ith to a smaller value than before. Thereby, the power conversion device 100 can realize a highly accurate synchronous rectification operation. In addition, the power conversion device 100 can lengthen the period during which the switching elements 311 and 312 that are controlled according to the polarity of the current are on, suppress a decrease in efficiency, and reduce loss to obtain a highly efficient system. be able to.
  • the control unit 10 controls on / off of the switching elements 311 and 312 by comparing the calculated absolute value of the predicted value Ie (n) with the current threshold value Ith, but is not limited thereto.
  • the control unit 10 turns on / off the switching elements 311 and 312 based on whether the calculated predicted value Ie (n) has become zero. May be controlled. Specifically, when the calculated predicted value Ie (n) becomes zero or has a polarity different from the current value Id (n), the control unit 10 performs control according to the polarity of the current.
  • the switching elements that are turned on among the switching elements are turned off.
  • the case where the predicted value Ie (n) has a different polarity from the current value Id (n) means that the current value Id (n) is positive and the predicted value Ie (n) is negative, or that the current value Id (n) is negative. ) Is negative and the predicted value Ie (n) is positive.
  • One method of increasing the switching speed of the switching element in the power conversion device 100 is a method of reducing the gate resistance of the switching element. As the gate resistance decreases, the charging / discharging time for the gate input capacitance becomes shorter, and the turn-on period and the turn-off period become shorter, so that the switching speed becomes faster.
  • the switching element by configuring the switching element with a WBG semiconductor such as GaN or SiC, loss per switching can be further suppressed, efficiency is further improved, and high-frequency switching can be performed. Further, by enabling high-frequency switching, the size of the reactor 2 can be reduced, and the size and weight of the power conversion device 100 can be reduced. In addition, by using a WBG semiconductor for the switching element, the switching speed is improved and the switching loss is suppressed, so that a heat radiation measure that allows the switching element to continue normal operation can be simplified. Further, by using a WBG semiconductor for the switching element, the switching frequency can be set to a sufficiently high value, for example, 16 kHz or more, so that noise due to switching can be suppressed.
  • a WBG semiconductor for the switching element the switching frequency can be set to a sufficiently high value, for example, 16 kHz or more, so that noise due to switching can be suppressed.
  • the GaN semiconductor In the GaN semiconductor, a two-dimensional electron gas is generated at the interface between the GaN layer and the aluminum gallium nitride layer, and the two-dimensional electron gas has high carrier mobility. Therefore, a switching element using a GaN semiconductor can realize high-speed switching.
  • the AC power supply 1 is a commercial power supply of 50 Hz / 60 Hz
  • the audible frequency ranges from 16 kHz to 20 kHz, that is, from 266 times to 400 times the frequency of the commercial power supply.
  • GaN semiconductors are suitable for switching at frequencies higher than the audible frequency.
  • the switching elements 311, 312, 321, and 322 made of a GaN semiconductor have extremely low switching loss even when driven at a switching frequency of several tens kHz or more, specifically, a switching frequency higher than 20 kHz. small. Therefore, no heat radiation measures are required, or the size of the heat radiation member used for the heat radiation measures can be reduced, and the power conversion device 100 can be reduced in size and weight. Further, since high-frequency switching becomes possible, the size of the reactor 2 can be reduced.
  • the switching frequency is preferably set to 150 kHz or less so that the primary component of the switching frequency does not fall within the measurement range of the noise terminal voltage standard.
  • the WBG semiconductor since the WBG semiconductor has a smaller capacitance than the Si semiconductor, the generation of the recovery current due to the switching is small, and the generation of the loss and the noise due to the recovery current can be suppressed. Therefore, the WBG semiconductor is suitable for high-frequency switching. .
  • the switching elements 311 and 312 of the first arm 31 having a larger number of switching times than the second arm 32 are formed of a GaN semiconductor.
  • the switching elements 321 and 322 of the small second arm 32 may be made of a SiC semiconductor. Thereby, the characteristics of each of the SiC semiconductor and the GaN semiconductor can be maximized. Further, by using the SiC semiconductor for the switching elements 321 and 322 of the second arm 32 having a smaller number of switching times than the first arm 31, the ratio of the conduction loss to the loss of the switching elements 321 and 322. And the turn-on loss and the turn-off loss are reduced.
  • the switching elements 321 and 322 of the second arm 32 having a small number of switching times may use a super junction (Super Junction: SJ) -MOSFET.
  • SJ super junction
  • SJ-MOSFET it is possible to suppress the demerit that the capacitance is high and the recovery is likely to occur while taking advantage of the low on-resistance, which is an advantage of the SJ-MOSFET.
  • the manufacturing cost of the second arm 32 can be reduced as compared with the case where a WBG semiconductor is used.
  • the WBG semiconductor has higher heat resistance than the Si semiconductor, and can operate even at a high junction temperature. Therefore, by using a WBG semiconductor, the first arm 31 and the second arm 32 can be configured with a small chip having high thermal resistance. In particular, a SiC semiconductor having a low yield at the time of manufacturing a chip can be reduced in cost by using it for a small chip.
  • the WBG semiconductor has higher heat resistance than the Si semiconductor, and has a higher allowable level of switching heat generation due to the bias of loss between the arms. Therefore, the WBG semiconductor is suitable for the first arm 31 in which switching loss occurs due to high-frequency driving.
  • FIG. 10 is a diagram illustrating an example of a hardware configuration that implements the control unit 10 included in the power conversion device 100 according to the first embodiment.
  • the control unit 10 is realized by the processor 201 and the memory 202.
  • the processor 201 is a CPU (Central Processing Unit), a central processing unit, a processing device, an arithmetic unit, a microprocessor, a microcomputer, a processor, a DSP (Digital Signal Processor), or a system LSI (Large Scale Integration).
  • the memory 202 is nonvolatile or volatile such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (registered trademark) (Electrically Erasable Programmable Read-Only Memory). Can be exemplified.
  • the memory 202 is not limited to these, and may be a magnetic disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).
  • control unit 10 determines whether current value Id (n ⁇ 1) detected by power supply current detection unit 6 last time and power supply current detection unit 6 Using the current value Id (n) detected this time, the predicted value Ie (n) of the current value detected next by the power supply current detector 6 is calculated.
  • the control unit 10 controls on / off of the switching elements 311 and 312 according to the calculated predicted value Ie (n). Thereby, the power conversion device 100 can improve the efficiency in the synchronous rectification operation while suppressing the generation of the backflow current.
  • the control unit 10 may calculate the predicted value Ie (n) even when the current value is increasing. Similarly, when the polarity of the current value is negative, the control unit 10 may calculate the predicted value Ie (n) even when the current value is decreasing.
  • the control unit 10 calculates the predicted value Ie (n) in the control cycle Ts at a fixed interval, but the present invention is not limited to this.
  • the control unit 10 does not need to frequently calculate the predicted value Ie (n) in a situation where the current value is increasing. Therefore, when the polarity of the current value is positive, the control unit 10 calculates the predicted value Ie (n) while the current value is decreasing, rather than the frequency of calculating the predicted value Ie (n) while the current value is increasing. Higher.
  • the control unit 10 calculates the predicted value Ie (n) while the current value is increasing from the frequency of calculating the predicted value Ie (n) while the current value is decreasing. Increase frequency. Thereby, the control unit 10 can reduce the processing load.
  • the control unit 10 does not have to calculate the predicted value Ie (n) when the current value Id (n) is zero. This is because the absolute value of the predicted value Ie (n) is already within the current threshold value Ith, so that the control unit 10 does not affect the process of turning off the switching element. In this case, similarly, the control unit 10 can reduce the processing load.
  • the processing of the present embodiment can be applied to switching elements other than MOSFETs as long as the switching element may cause a reverse current due to a delay in the switching processing.
  • control unit 10 of power conversion device 100 predicts the current value detected by power supply current detection unit 6 using the current value detected by power supply current detection unit 6.
  • the present invention is not limited to this.
  • the control unit 10 can also predict the next voltage value detected by the power supply voltage detection unit 5 using the voltage value detected by the power supply voltage detection unit 5 using the same method.
  • control unit 10 controls on / off of the switching elements 321 and 322 in accordance with the polarity of the power supply voltage Vs, and controls on / off of the switching elements 311 and 312 in accordance with the polarity of the power supply current Is.
  • the control unit 10 may control on / off of the switching elements 311 and 312 according to the polarity of the power supply voltage Vs, and may control on / off of the switching elements 321 and 322 according to the polarity of the power supply current Is.
  • Embodiment 2 FIG.
  • control unit 10 controls on / off of switching elements 311 and 312 according to calculated predicted value Ie (n). Therefore, even when the absolute value of the current value of the current actually flowing to the power conversion device 100 is larger than the current threshold value Ith, the control unit 10 sometimes turns off the switching elements 311 and 312 early.
  • control unit 10 estimates the time at which the absolute value of the current value of the current flowing through power conversion device 100 reaches current threshold Ith, and turns off switching elements 311 and 312 at the estimated time.
  • the configuration of power conversion device 100 is the same as the configuration in the first embodiment shown in FIG.
  • the control unit 10 excludes the case where the absolute value of the predicted value Ie (n) is the same as the current threshold value Ith.
  • the predicted value Ie (n) is replaced with the current threshold value Ith, and the last control cycle Ts indicating the elapsed time is determined by the time when the predicted value Ie (n) becomes the current threshold value Ith.
  • the estimated time Tith is replaced with the estimated time Tith, the following equation (3) is obtained.
  • equation (4) for obtaining estimated time Tith can be obtained.
  • ⁇ Tith ((Id (n) ⁇ Ith) / (Id (n ⁇ 1) ⁇ Id (n))) ⁇ Ts ⁇ (4)
  • the control unit 10 When the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith, the control unit 10 performs control according to the polarity of the current after the estimated time Tith has elapsed from the time of the nth control timing. Control is performed to turn off the switching elements that are turned on among the switching elements.
  • the control unit 10 when the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith, the control unit 10 performs control according to the polarity of the current from the time of the nth control timing to the estimated time Tith. Control is performed to turn off the switching elements that are turned on among the switching elements.
  • the control unit 10 uses, for example, a control signal for generating a control cycle Ts so that the switching element can be turned off after the estimated time Tith has elapsed from the timing shown in FIG. 11, that is, the time point of the n-th control timing.
  • the control unit 10 generates a control signal using, for example, a switching timer that counts the control cycle Ts.
  • the control unit 10 generates a power supply current for compare match from the detected current value, and performs a compare match using the power supply current for compare match and the control signal.
  • the power supply current for compare match is a signal whose current value is set to a level that does not intersect with the control signal while the power supply current Is is increasing.
  • the control unit 10 turns off the switching element 311 at the timing when the power supply current for compare match and the control signal overlap. When the current value has a positive polarity, the control unit 10 may not perform the compare match while the current value increases.
  • control unit 10 calculates Tith when the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith has been described, but the present invention is not limited thereto.
  • the control unit 10 may calculate Tith before the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith.
  • control unit 10 controls the on / off of the switching elements 311 and 312 based on whether the calculated predicted value Ie (n) has become zero, the control unit 10 estimates that the predicted value Ie (n) becomes zero.
  • the time T0 is calculated. Specifically, the following equation (5) can be obtained by replacing "Ith" with "0" in equation (4).
  • ⁇ T0 (Id (n) / (Id (n-1) -Id (n))) ⁇ Ts ⁇ (5)
  • control unit 10 controls power conversion device 100 when the absolute value of calculated predicted value Ie (n) is equal to or smaller than current threshold value Ith.
  • the time at which the absolute value of the current value of the flowing current becomes the current threshold value Ith is estimated, and the switching element is turned off at the estimated time.
  • Embodiment 3 FIG. In the third embodiment, a motor driving device including the power conversion device 100 described in the first and second embodiments will be described.
  • FIG. 12 is a diagram illustrating a configuration example of a motor driving device 101 according to the third embodiment.
  • the motor driving device 101 drives a motor 42 as a load.
  • the motor drive device 101 includes the power conversion devices 100 according to the first and second embodiments, an inverter 41, a motor current detection unit 44, and an inverter control unit 43.
  • the inverter 41 drives the motor 42 by converting DC power supplied from the power converter 100 into AC power and outputting the AC power to the motor 42.
  • the load of the motor driving device 101 is the motor 42
  • the device connected to the inverter 41 may be a device to which AC power is input. Other devices may be used.
  • the inverter 41 is a circuit in which a switching element such as an IGBT (Insulated Gate Bipolar Transistor) has a three-phase bridge configuration or a two-phase bridge configuration.
  • the switching element used for the inverter 41 is not limited to the IGBT, but may be a switching element made of a WBG semiconductor, an IGCT (Integrated Gate Commutated Thyristor), an FET (Field Effect Transistor) or a MOSFET.
  • the motor current detector 44 detects a current flowing between the inverter 41 and the motor 42.
  • the inverter control unit 43 uses the current detected by the motor current detection unit 44 to generate a PWM signal for driving a switching element in the inverter 41 so that the motor 42 rotates at a desired rotation speed.
  • the inverter control unit 43 is realized by a processor and a memory, similarly to the control unit 10. Note that the inverter control unit 43 of the motor drive device 101 and the control unit 10 of the power conversion device 100 may be realized by one circuit.
  • the bus voltage Vdc necessary for controlling the bridge circuit 3 changes according to the operation state of the motor 42.
  • the bus voltage Vdc output from power conversion device 100 A region where the output voltage from the inverter 41 saturates beyond the upper limit limited by the bus voltage Vdc is called an overmodulation region.
  • the number of windings on the stator of the motor 42 can be increased accordingly.
  • the number of windings of the motor 42 is set to an appropriate value.
  • the use of the power converter 100 reduces the bias of heat generation between the arms, and realizes a highly reliable and high-output motor drive device 101.
  • Embodiment 4 FIG. In the fourth embodiment, an air conditioner including the motor drive device 101 described in the third embodiment will be described.
  • FIG. 13 is a diagram illustrating a configuration example of an air conditioner 700 according to Embodiment 4.
  • the air conditioner 700 is an example of a refrigeration cycle device, and includes the motor driving device 101 and the motor 42 according to the third embodiment.
  • the air conditioner 700 includes a compressor 81 including a compression mechanism 87 and a motor 42, a four-way valve 82, an outdoor heat exchanger 83, an expansion valve 84, an indoor heat exchanger 85, and a refrigerant pipe 86.
  • the air conditioner 700 is not limited to a separate type air conditioner in which an outdoor unit is separated from an indoor unit, and includes a compressor 81, an indoor heat exchanger 85, and an outdoor heat exchanger 83 provided in one housing.
  • a body type air conditioner may be used.
  • the motor 42 is driven by the motor driving device 101.
  • a compression mechanism 87 for compressing the refrigerant and a motor 42 for operating the compression mechanism 87 are provided inside the compressor 81.
  • the refrigerant circulates through the compressor 81, the four-way valve 82, the outdoor heat exchanger 83, the expansion valve 84, the indoor heat exchanger 85, and the refrigerant pipe 86 to form a refrigeration cycle.
  • the components included in the air conditioner 700 can be applied to devices such as a refrigerator or a freezer including a refrigeration cycle.
  • the configuration example in which the motor 42 is used as the driving source of the compressor 81 and the motor 42 is driven by the motor driving device 101 has been described.
  • the motor 42 may be applied to a drive source for driving an indoor unit blower and an outdoor unit blower (not shown) included in the air conditioner 700, and the motor 42 may be driven by the motor driving device 101.
  • the motor 42 may be applied to a drive source of the indoor unit blower, the outdoor unit blower, and the compressor 81, and the motor 42 may be driven by the motor driving device 101.
  • the reactor 2 can be downsized by the interleave method. However, in the air conditioner 700, there are many operations under intermediate conditions. Therefore, the reactor 2 does not need to be downsized. However, it is effective in terms of suppressing harmonics and power factor.
  • the power converter 100 can suppress the switching loss, the temperature rise of the power converter 100 is suppressed, and even if the size of the outdoor unit blower (not shown) is reduced, the size of the board mounted on the power converter 100 can be reduced. Cooling capacity can be secured. Therefore, the power converter 100 is suitable for an air conditioner 700 having high efficiency and high output of 4.0 kW or more.
  • the high-frequency driving of the switching element can reduce the switching loss, realize a low energy consumption rate, and realize a highly efficient air conditioner 700.

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Abstract

The present invention comprises: a reactor (2) having a first end part and a second end part, the first end part being connected to an AC power supply (1); a bridge circuit (3) connected to the second end part of the reactor (2), the bridge circuit (3) comprising at least one or more switching elements and converting an AC voltage outputted from the AC power supply (1) into a DC voltage; a power supply current detector (6) that detects a current of the AC power supply (1); and a control unit (10) that controls the ON/OFF state of the switching element in accordance with a current value detected by the power supply current detector (6). The control unit (10) controls the ON/OFF state using a past current value detected by the power supply current detector (6).

Description

電力変換装置、モータ駆動装置及び空気調和機Power converter, motor drive, and air conditioner
 本発明は、交流電力を直流電力に変換する電力変換装置、モータ駆動装置及び空気調和機に関する。 The present invention relates to a power conversion device that converts AC power into DC power, a motor drive device, and an air conditioner.
 スイッチング素子で構成されたブリッジ回路を用いて、供給された交流電力を直流電力に変換して出力する電力変換装置がある。電力変換装置は、スイッチング素子をオンオフすることで、交流電力の電圧を昇圧する昇圧動作、及び交流電力を整流する同期整流動作を行うことができる。 電力 There is a power conversion device that converts supplied AC power into DC power and outputs the converted power by using a bridge circuit composed of switching elements. The power conversion device can perform a boosting operation of boosting the voltage of AC power and a synchronous rectification operation of rectifying AC power by turning on and off the switching element.
 特許文献1には、電力変換装置が、交流電源から供給される交流電力の電圧、及び交流電源に流れる電流に応じて、4つのスイッチング素子のうち、2つのスイッチング素子を電圧の極性に応じて制御し、他の2つのスイッチング素子を電流の極性に応じて制御する技術が開示されている。特許文献1に記載の電力変換装置は、電流の極性が正の場合、電流の極性に応じて制御する2つのスイッチング素子のうち、電流値の絶対値が判定値a以上になると一方のスイッチング素子をオンし、電流値の絶対値が判定値aより小さい判定値b以下になると一方のスイッチング素子をオフする。また、特許文献1に記載の電力変換装置は、電流の極性が負の場合、電流の極性に応じて制御する2つのスイッチング素子のうち、電流値の絶対値が判定値a以上になると他方のスイッチング素子をオンし、電流値の絶対値が判定値b以下になると他方のスイッチング素子をオフする。特許文献1に記載の電力変換装置は、2つの判定値を用いることで、スイッチング素子のオン期間を長くして効率を向上している。 Patent Literature 1 discloses that a power conversion device sets two switching elements of four switching elements according to a polarity of a voltage according to a voltage of AC power supplied from an AC power supply and a current flowing to the AC power supply. There is disclosed a technique for controlling the other two switching elements in accordance with the polarity of the current. In the power conversion device described in Patent Document 1, when the polarity of the current is positive, one of the two switching elements controlled according to the polarity of the current when the absolute value of the current value becomes equal to or greater than the determination value a. Is turned on, and when the absolute value of the current value becomes equal to or smaller than the judgment value b smaller than the judgment value a, one of the switching elements is turned off. Further, in the power conversion device described in Patent Document 1, when the polarity of the current is negative, of the two switching elements controlled according to the polarity of the current, when the absolute value of the current value is equal to or greater than the determination value a, the other switching element is controlled. The switching element is turned on, and when the absolute value of the current value becomes equal to or smaller than the determination value b, the other switching element is turned off. The power conversion device described in Patent Literature 1 uses two determination values to increase the on-period of the switching element and improve the efficiency.
特開2018-7326号公報JP 2018-7326 A
 しかしながら、特許文献1に記載の電力変換装置は、電流値の絶対値が判定値aよりも小さい判定値b以下になるとスイッチング素子をオフにする。そのため、特許文献1に記載の電力変換装置は、判定値bの設定次第では、スイッチング素子をオフにする処理が遅れると電流値がゼロになってからオフすることになり、同期整流動作において直流電圧側から交流電源側への逆流電流が発生する可能性がある、という問題があった。 However, the power conversion device described in Patent Literature 1 turns off the switching element when the absolute value of the current value becomes equal to or smaller than the determination value b smaller than the determination value a. For this reason, the power conversion device described in Patent Literature 1 turns off after the current value becomes zero if the process of turning off the switching element is delayed depending on the setting of the determination value b. There is a problem that a reverse current may flow from the voltage side to the AC power supply side.
 本発明は、上記に鑑みてなされたものであって、逆流電流の発生を抑制しつつ、同期整流動作において効率を向上可能な電力変換装置を得ることを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to provide a power converter capable of improving efficiency in synchronous rectification operation while suppressing generation of a backflow current.
 上述した課題を解決し、目的を達成するために、本発明に係る電力変換装置は、第一端部と第二端部を有し、第一端部が交流電源に接続されるリアクトルと、リアクトルの第二端部に接続され、少なくとも1つ以上のスイッチング素子を備え、交流電源から出力される交流電圧を直流電圧に変換するブリッジ回路と、交流電源の電流を検出する電流検出部と、電流検出部で検出された電流値に応じてスイッチング素子のオンオフを制御する制御部と、を備え、制御部は電流検出部で検出された過去の電流値を用いてオンオフ制御する。 In order to solve the above-described problems and achieve the object, a power converter according to the present invention has a reactor having a first end and a second end, the first end being connected to an AC power supply, A bridge circuit that is connected to the second end of the reactor and includes at least one or more switching elements, converts an AC voltage output from an AC power supply into a DC voltage, and a current detection unit that detects a current of the AC power supply, A control unit that controls on / off of the switching element in accordance with the current value detected by the current detection unit. The control unit performs on / off control using a past current value detected by the current detection unit.
 本発明に係る電力変換装置は、逆流電流の発生を抑制しつつ、同期整流動作において効率を向上できる、という効果を奏する。 The power converter according to the present invention has an effect that the efficiency in the synchronous rectification operation can be improved while suppressing the generation of the backflow current.
実施の形態1に係る電力変換装置の構成例を示す図FIG. 2 is a diagram illustrating a configuration example of a power conversion device according to the first embodiment. MOSFETの概略構造を示す模式的断面図Schematic sectional view showing a schematic structure of a MOSFET 電源電流の絶対値が電流閾値より大きく、かつ、電源電圧極性が正のとき、実施の形態1に係る電力変換装置に流れる電流の経路を示す第1の図1 is a first diagram illustrating a path of a current flowing through a power conversion device according to a first embodiment when an absolute value of a power supply current is larger than a current threshold value and a power supply voltage polarity is positive. 電源電流の絶対値が電流閾値より大きく、かつ、電源電圧極性が負のとき、実施の形態1に係る電力変換装置に流れる電流の経路を示す第1の図FIG. 1 is a first diagram illustrating a path of a current flowing through the power conversion device according to the first embodiment when the absolute value of the power supply current is larger than a current threshold value and the power supply voltage polarity is negative. 電源電流の絶対値が電流閾値より大きく、かつ、電源電圧極性が正のとき、実施の形態1に係る電力変換装置に流れる電流の経路を示す第2の図Second diagram showing a path of a current flowing through the power converter according to Embodiment 1 when the absolute value of the power supply current is larger than the current threshold value and the power supply voltage polarity is positive. 電源電流の絶対値が電流閾値より大きく、かつ、電源電圧極性が負のとき、実施の形態1に係る電力変換装置に流れる電流の経路を示す第2の図Second diagram showing a path of a current flowing through the power converter according to the first embodiment when the absolute value of the power supply current is larger than the current threshold value and the power supply voltage polarity is negative. 実施の形態1に係る電力変換装置において制御部がスイッチング素子をオンするタイミングを示す図The figure which shows the timing which a control part turns on a switching element in the power converter device concerning Embodiment 1. 実施の形態1に係る電力変換装置の制御部が、電源電流検出部で次に検出される電流値の予測値を算出する処理を示す図FIG. 5 is a diagram showing a process in which the control unit of the power conversion device according to the first embodiment calculates a predicted value of a current value detected next by the power supply current detection unit. 実施の形態1に係る電力変換装置の制御部が電源電流の極性に応じてオンオフを制御するスイッチング素子に対する処理を示すフローチャート5 is a flowchart showing processing performed by the control unit of the power conversion device according to the first embodiment for a switching element that controls on / off in accordance with the polarity of the power supply current. 実施の形態1に係る電力変換装置が備える制御部を実現するハードウェア構成の一例を示す図FIG. 3 is a diagram illustrating an example of a hardware configuration that realizes a control unit included in the power conversion device according to the first embodiment. 実施の形態2に係る電力変換装置の制御部がスイッチング素子をオンするタイミングを示す図The figure which shows the timing which the control part of the electric power converter concerning Embodiment 2 turns on a switching element. 実施の形態3に係るモータ駆動装置の構成例を示す図FIG. 7 is a diagram illustrating a configuration example of a motor drive device according to a third embodiment. 実施の形態4に係る空気調和機の構成例を示す図The figure which shows the example of a structure of the air conditioner which concerns on Embodiment 4.
 以下に、本発明の実施の形態に係る電力変換装置、モータ駆動装置及び空気調和機を図面に基づいて詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。 Hereinafter, a power conversion device, a motor drive device, and an air conditioner according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.
実施の形態1.
 図1は、本発明の実施の形態1に係る電力変換装置100の構成例を示す図である。電力変換装置100は、ブリッジ回路3を用いて、交流電源1から供給される交流電力を直流電力に変換して負荷50に印加する交流直流変換機能を有する電源装置である。図1に示すように、電力変換装置100は、リアクタ2と、ブリッジ回路3と、平滑コンデンサ4と、電源電圧検出部5と、電源電流検出部6と、母線電圧検出部7と、制御部10とを備える。リアクタ2は、第1端部と第2端部とを備え、第1端部が交流電源1に接続される。
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a power conversion device 100 according to Embodiment 1 of the present invention. The power conversion device 100 is a power supply device having an AC / DC conversion function of converting AC power supplied from the AC power supply 1 to DC power and applying the DC power to the load 50 using the bridge circuit 3. As shown in FIG. 1, the power conversion device 100 includes a reactor 2, a bridge circuit 3, a smoothing capacitor 4, a power supply voltage detector 5, a power supply current detector 6, a bus voltage detector 7, a controller, 10 is provided. Reactor 2 has a first end and a second end, and the first end is connected to AC power supply 1.
 ブリッジ回路3は、ダイオードが並列接続されたスイッチング素子が2つ直列接続されたアームを2つ備え、2つのアームが並列接続された回路である。具体的には、ブリッジ回路3は、第1の回路である第1のアーム31と、第2の回路である第2のアーム32とを備える。第1のアーム31は、直列接続されるスイッチング素子311及びスイッチング素子312を備える。スイッチング素子311には寄生ダイオード311aが形成される。寄生ダイオード311aは、スイッチング素子311のドレインとソースとの間に並列接続される。スイッチング素子312には寄生ダイオード312aが形成される。寄生ダイオード312aは、スイッチング素子312のドレインとソースとの間に並列接続される。寄生ダイオード311a,312aのそれぞれは、還流ダイオードとして使用されるダイオードである。 The bridge circuit 3 is a circuit including two arms in which two switching elements each having a diode connected in parallel are connected in series, and two arms connected in parallel. Specifically, the bridge circuit 3 includes a first arm 31 that is a first circuit and a second arm 32 that is a second circuit. The first arm 31 includes a switching element 311 and a switching element 312 connected in series. A parasitic diode 311a is formed in the switching element 311. The parasitic diode 311a is connected in parallel between the drain and the source of the switching element 311. A parasitic diode 312a is formed in the switching element 312. The parasitic diode 312a is connected in parallel between the drain and the source of the switching element 312. Each of the parasitic diodes 311a and 312a is a diode used as a freewheeling diode.
 第2のアーム32は、直列接続されたスイッチング素子321及びスイッチング素子322を備える。第2のアーム32は、第1のアーム31に並列接続される。スイッチング素子321には寄生ダイオード321aが形成される。寄生ダイオード321aは、スイッチング素子321のドレインとソースとの間に並列接続される。スイッチング素子322には寄生ダイオード322aが形成される。寄生ダイオード322aは、スイッチング素子322のドレインとソースとの間に並列接続される。寄生ダイオード321a,322aのそれぞれは、還流ダイオードとして使用されるダイオードである。 The second arm 32 includes a switching element 321 and a switching element 322 connected in series. The second arm 32 is connected in parallel to the first arm 31. The switching element 321 is formed with a parasitic diode 321a. The parasitic diode 321a is connected in parallel between the drain and the source of the switching element 321. The switching element 322 is formed with a parasitic diode 322a. The parasitic diode 322a is connected in parallel between the drain and the source of the switching element 322. Each of the parasitic diodes 321a and 322a is a diode used as a freewheeling diode.
 詳細には、電力変換装置100は、それぞれが交流電源1に接続される第1の配線501及び第2の配線502と、第1の配線501に配置されるリアクタ2とを備える。また、第1のアーム31は、第1のスイッチング素子であるスイッチング素子311と、第2のスイッチング素子であるスイッチング素子312と、第1の接続点506を有する第3の配線503とを備える。スイッチング素子311及びスイッチング素子312は、第3の配線503により直列に接続される。第1の接続点506には第1の配線501が接続される。第1の接続点506は、第1の配線501及びリアクタ2を介して、交流電源1に接続される。第1の接続点506は、リアクタ2の第2端部に接続される。 Specifically, the power conversion device 100 includes a first wiring 501 and a second wiring 502, each of which is connected to the AC power supply 1, and a reactor 2 arranged on the first wiring 501. Further, the first arm 31 includes a switching element 311 as a first switching element, a switching element 312 as a second switching element, and a third wiring 503 having a first connection point 506. The switching element 311 and the switching element 312 are connected in series by a third wiring 503. The first wiring 501 is connected to the first connection point 506. The first connection point 506 is connected to the AC power supply 1 via the first wiring 501 and the reactor 2. The first connection point 506 is connected to the second end of the reactor 2.
 第2のアーム32は、第3のスイッチング素子であるスイッチング素子321と、第4のスイッチング素子であるスイッチング素子322と、第2の接続点508を備える第4の配線504とを備え、スイッチング素子321及びスイッチング素子322は、第4の配線504により直列に接続される。第2の接続点508には第2の配線502が接続される。第2の接続点508は、第2の配線502を介して交流電源1に接続される。なお、ブリッジ回路3は、少なくとも1つ以上のスイッチング素子を備え、交流電源1から出力される交流電圧を直流電圧に変換できればよい。 The second arm 32 includes a switching element 321 as a third switching element, a switching element 322 as a fourth switching element, and a fourth wiring 504 including a second connection point 508. 321 and the switching element 322 are connected in series by the fourth wiring 504. The second wiring 502 is connected to the second connection point 508. Second connection point 508 is connected to AC power supply 1 via second wiring 502. The bridge circuit 3 may include at least one or more switching elements, and may convert an AC voltage output from the AC power supply 1 into a DC voltage.
 平滑コンデンサ4は、ブリッジ回路3、詳細には第2のアーム32に並列接続されるコンデンサである。ブリッジ回路3では、スイッチング素子311の一端が平滑コンデンサ4の正側に接続され、スイッチング素子311の他端とスイッチング素子312の一端とが接続され、スイッチング素子312の他端が平滑コンデンサ4の負側に接続されている。 The smoothing capacitor 4 is a capacitor connected in parallel to the bridge circuit 3, more specifically, to the second arm 32. In the bridge circuit 3, one end of the switching element 311 is connected to the positive side of the smoothing capacitor 4, the other end of the switching element 311 is connected to one end of the switching element 312, and the other end of the switching element 312 is connected to the negative side of the smoothing capacitor 4. Connected to the side.
 スイッチング素子311,312,321,322は、MOSFETで構成される。スイッチング素子311,312,321,322には、窒化ガリウム(Gallium Nitride:GaN)、炭化珪素(Silicon Carbide:SiC)、ダイヤモンドまたは窒化アルミニウムといったワイドバンドギャップ(Wide Band Gap:WBG)半導体で構成されたMOSFETを用いることができる。スイッチング素子311,312,321,322にWBG半導体を用いることにより、耐電圧性が高く、許容電流密度も高くなるため、モジュールの小型化が可能となる。WBG半導体は、耐熱性も高いため、放熱部の放熱フィンの小型化も可能になる。 The switching elements 311, 312, 321, 322 are composed of MOSFETs. The switching elements 311, 312, 321, and 322 are formed of a wide band gap (WBG) semiconductor such as gallium nitride (GaN), silicon carbide (Silicon Carbide: SiC), diamond, or aluminum nitride. MOSFETs can be used. By using a WBG semiconductor for the switching elements 311, 312, 321, and 322, the withstand voltage is high and the allowable current density is high, so that the module can be downsized. Since the WBG semiconductor has high heat resistance, it is also possible to reduce the size of the heat radiation fins of the heat radiation part.
 制御部10は、電源電圧検出部5、電源電流検出部6及び母線電圧検出部7からそれぞれ出力される信号に基づいて、ブリッジ回路3のスイッチング素子311,312,321,322を動作させる駆動パルスを生成する。電源電圧検出部5は、交流電源1の出力電圧の電圧値である電源電圧Vsを検出し、検出結果を示す電気信号を制御部10へ出力する電圧検出部である。電源電流検出部6は、交流電源1から出力される電流の電流値である電源電流Isを検出し、検出結果を示す電気信号を制御部10へ出力する電流検出部である。電源電流Isは、交流電源1とブリッジ回路3との間に流れる電流の電流値である。母線電圧検出部7は、母線電圧Vdcを検出し、検出結果を示す電気信号を制御部10へ出力する電圧検出部である。母線電圧Vdcは、ブリッジ回路3の出力電圧を平滑コンデンサ4で平滑した電圧である。制御部10は、電源電圧Vs、電源電流Is、及び母線電圧Vdcに応じてスイッチング素子311,312,321,322のオンオフを制御する。なお、制御部10は、電源電圧Vs、電源電流Is、及び母線電圧Vdcのうち、少なくとも1つを用いてスイッチング素子311,312,321,322のオンオフを制御してもよい。 The control unit 10 drives the switching pulses 311, 312, 321, and 322 of the bridge circuit 3 based on signals output from the power supply voltage detection unit 5, the power supply current detection unit 6, and the bus voltage detection unit 7. Generate The power supply voltage detector 5 is a voltage detector that detects a power supply voltage Vs, which is a voltage value of an output voltage of the AC power supply 1, and outputs an electric signal indicating a detection result to the controller 10. The power supply current detection unit 6 is a current detection unit that detects the power supply current Is, which is the current value of the current output from the AC power supply 1, and outputs an electric signal indicating the detection result to the control unit 10. The power supply current Is is a current value of a current flowing between the AC power supply 1 and the bridge circuit 3. The bus voltage detection unit 7 is a voltage detection unit that detects the bus voltage Vdc and outputs an electric signal indicating the detection result to the control unit 10. The bus voltage Vdc is a voltage obtained by smoothing the output voltage of the bridge circuit 3 with the smoothing capacitor 4. The control unit 10 controls ON / OFF of the switching elements 311, 312, 321, 322 according to the power supply voltage Vs, the power supply current Is, and the bus voltage Vdc. The control unit 10 may control on / off of the switching elements 311, 312, 321, 322 by using at least one of the power supply voltage Vs, the power supply current Is, and the bus voltage Vdc.
 次に、実施の形態1に係る電力変換装置100の基本的な動作を説明する。以下では、交流電源1の正側すなわち交流電源1の正極端子に接続されるスイッチング素子311,321を、上側スイッチング素子と称する場合がある。また、交流電源1の負側すなわち交流電源1の負極端子に接続されるスイッチング素子312,322を、下側スイッチング素子と称する場合がある。 Next, a basic operation of the power conversion device 100 according to Embodiment 1 will be described. Hereinafter, switching elements 311 and 321 connected to the positive side of AC power supply 1, that is, the positive terminal of AC power supply 1, may be referred to as upper switching elements. Further, switching elements 312 and 322 connected to the negative side of AC power supply 1, that is, the negative terminal of AC power supply 1, may be referred to as lower switching elements.
 第1のアーム31では、上側スイッチング素子と下側スイッチング素子は相補的に動作する。すなわち、上側スイッチング素子及び下側スイッチング素子のうち、一方がオンの場合には他方はオフである。第1のアーム31を構成するスイッチング素子311,312は、後述するように、制御部10により生成される駆動信号であるPWM(Pulse Width Modulation)信号により駆動される。PWM信号に従ったスイッチング素子311,312のオンまたはオフの動作を、以下ではスイッチング動作とも呼ぶ。交流電源1及びリアクタ2を介した平滑コンデンサ4の短絡を防ぐため、交流電源1から出力される電源電流Isの絶対値が電流閾値以下の場合には、スイッチング素子311及びスイッチング素子312はともにオフとなる。以下では、平滑コンデンサ4の短絡をコンデンサ短絡と称する。コンデンサ短絡は、平滑コンデンサ4に蓄えられたエネルギーが放出され、交流電源1に電流が回生される状態である。 で は In the first arm 31, the upper switching element and the lower switching element operate complementarily. That is, when one of the upper switching element and the lower switching element is on, the other is off. The switching elements 311 and 312 constituting the first arm 31 are driven by a PWM (Pulse Width Modulation) signal which is a drive signal generated by the control unit 10 as described later. The operation of turning on or off the switching elements 311 and 312 according to the PWM signal is hereinafter also referred to as a switching operation. When the absolute value of the power supply current Is output from the AC power supply 1 is equal to or less than the current threshold, the switching element 311 and the switching element 312 are both turned off to prevent a short circuit of the smoothing capacitor 4 via the AC power supply 1 and the reactor 2. Becomes Hereinafter, a short circuit of the smoothing capacitor 4 is referred to as a capacitor short circuit. The capacitor short-circuit is a state in which the energy stored in the smoothing capacitor 4 is released and the current is regenerated in the AC power supply 1.
 第2のアーム32を構成するスイッチング素子321,322は、制御部10により生成される駆動信号によりオンまたはオフとなる。スイッチング素子321,322は、基本的には、交流電源1から出力される電圧の極性である電源電圧極性に応じてオンまたはオフの状態となる。具体的には、電源電圧極性が正の場合、スイッチング素子322はオンであり、かつ、スイッチング素子321はオフであり、電源電圧極性が負の場合、スイッチング素子321はオンであり、かつ、スイッチング素子322はオフである。なお、図1では、制御部10からブリッジ回路3へ向かう矢印でスイッチング素子321,322のオンオフを制御する駆動信号、及びスイッチング素子311,312のオンオフを制御する前述のPWM信号を示している。 The switching elements 321 and 322 constituting the second arm 32 are turned on or off by a drive signal generated by the control unit 10. The switching elements 321 and 322 are basically turned on or off according to the power supply voltage polarity that is the polarity of the voltage output from the AC power supply 1. Specifically, when the power supply voltage polarity is positive, the switching element 322 is on and the switching element 321 is off, and when the power supply voltage polarity is negative, the switching element 321 is on and Element 322 is off. In FIG. 1, the drive signal for controlling the on / off of the switching elements 321 and 322 and the PWM signal for controlling the on / off of the switching elements 311 and 312 are indicated by arrows from the control unit 10 to the bridge circuit 3.
 次に、実施の形態1におけるスイッチング素子の状態と実施の形態1に係る電力変換装置100に流れる電流の経路との関係を説明する。なお、本説明の前に、MOSFETの構造について、図2を参照して説明する。 Next, the relationship between the state of the switching element according to the first embodiment and the path of the current flowing through power conversion device 100 according to the first embodiment will be described. Prior to this description, the structure of the MOSFET will be described with reference to FIG.
 図2は、MOSFETの概略構造を示す模式的断面図である。図2には、n型MOSFETが例示される。n型MOSFETの場合、図2に示すように、p型の半導体基板600が用いられる。半導体基板600には、ソース電極S、ドレイン電極D及びゲート電極Gが形成される。ソース電極S及びドレイン電極Dと接する部位には、高濃度の不純物がイオン注入されてn型の領域601が形成される。また、半導体基板600において、n型の領域601が形成されない部位とゲート電極Gとの間には、酸化絶縁膜602が形成される。すなわち、ゲート電極Gと、半導体基板600におけるp型の領域603との間には、酸化絶縁膜602が介在している。 FIG. 2 is a schematic sectional view showing a schematic structure of the MOSFET. FIG. 2 illustrates an n-type MOSFET. In the case of an n-type MOSFET, a p-type semiconductor substrate 600 is used as shown in FIG. On the semiconductor substrate 600, a source electrode S, a drain electrode D, and a gate electrode G are formed. High-concentration impurities are ion-implanted into a portion in contact with the source electrode S and the drain electrode D to form an n-type region 601. In the semiconductor substrate 600, an oxide insulating film 602 is formed between a portion where the n-type region 601 is not formed and the gate electrode G. That is, the oxide insulating film 602 is interposed between the gate electrode G and the p-type region 603 in the semiconductor substrate 600.
 ゲート電極Gに正電圧が印加されると、半導体基板600におけるp型の領域603と酸化絶縁膜602との間の境界面に電子が引き寄せられ、当該境界面が負に帯電する。電子が集まった所は、電子の密度がホール密度よりも高くなりn型化する。このn型化した部分は電流の通り道となりチャネル604と呼ばれる。チャネル604は、図2の例では、n型チャネルである。MOSFETがオンに制御されることにより、通流する電流は、p型の領域603に形成される寄生ダイオードよりも、チャネル604に多く流れる。 (4) When a positive voltage is applied to the gate electrode G, electrons are attracted to a boundary between the p-type region 603 and the oxide insulating film 602 in the semiconductor substrate 600, and the boundary is negatively charged. At the place where the electrons are gathered, the density of the electrons becomes higher than the hole density and becomes n-type. This n-type portion becomes a path for current flow and is called a channel 604. The channel 604 is an n-type channel in the example of FIG. By controlling the MOSFET to be turned on, a larger amount of current flows through the channel 604 than a parasitic diode formed in the p-type region 603.
 図3は、電源電流Isの絶対値が電流閾値より大きく、かつ、電源電圧極性が正のとき、実施の形態1に係る電力変換装置100に流れる電流の経路を示す第1の図である。図3では、電源電圧極性が正であり、スイッチング素子311及びスイッチング素子322がオンであり、スイッチング素子312及びスイッチング素子321がオフである。この状態では、交流電源1、リアクタ2、スイッチング素子311、平滑コンデンサ4、スイッチング素子322、交流電源1の順序で電流が流れる。このように、実施の形態1では、寄生ダイオード311a及び寄生ダイオード322aに電流が流れるのではなく、スイッチング素子311及びスイッチング素子322のそれぞれのチャネルに電流が流れることで、同期整流動作が行われる。なお、図3では、オンしているスイッチング素子を丸印で示している。以降の図においても同様とする。 FIG. 3 is a first diagram showing a path of a current flowing through power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is positive. In FIG. 3, the power supply voltage polarity is positive, the switching element 311 and the switching element 322 are on, and the switching element 312 and the switching element 321 are off. In this state, current flows in the order of AC power supply 1, reactor 2, switching element 311, smoothing capacitor 4, switching element 322, and AC power supply 1. As described above, in the first embodiment, the synchronous rectification operation is performed by causing the current not to flow through the parasitic diode 311a and the parasitic diode 322a but to flow through each channel of the switching element 311 and the switching element 322. In FIG. 3, the switching elements that are turned on are indicated by circles. The same applies to the following drawings.
 図4は、電源電流Isの絶対値が電流閾値より大きく、かつ、電源電圧極性が負のとき、実施の形態1に係る電力変換装置100に流れる電流の経路を示す第1の図である。図4では、電源電圧極性が負であり、スイッチング素子312及びスイッチング素子321がオンであり、スイッチング素子311及びスイッチング素子322がオフである。この状態では、交流電源1、スイッチング素子321、平滑コンデンサ4、スイッチング素子312、リアクタ2、交流電源1の順序で電流が流れる。このように、実施の形態1では、寄生ダイオード321a及び寄生ダイオード312aに電流が流れるのではなく、スイッチング素子321及びスイッチング素子312のそれぞれのチャネルに電流が流れることで、同期整流動作が行われる。 FIG. 4 is a first diagram illustrating a path of a current flowing in power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is negative. In FIG. 4, the power supply voltage polarity is negative, the switching element 312 and the switching element 321 are on, and the switching element 311 and the switching element 322 are off. In this state, current flows in the order of the AC power supply 1, the switching element 321, the smoothing capacitor 4, the switching element 312, the reactor 2, and the AC power supply 1. As described above, in the first embodiment, the synchronous rectification operation is performed by causing the current not to flow through the parasitic diode 321a and the parasitic diode 312a but to flow through each channel of the switching element 321 and the switching element 312.
 図5は、電源電流Isの絶対値が電流閾値より大きく、かつ、電源電圧極性が正のとき、実施の形態1に係る電力変換装置100に流れる電流の経路を示す第2の図である。図5では、電源電圧極性が正であり、スイッチング素子312及びスイッチング素子322がオンであり、スイッチング素子311及びスイッチング素子321がオフである。この状態では、交流電源1、リアクタ2、スイッチング素子312、スイッチング素子322、交流電源1の順序で電流が流れ、平滑コンデンサ4を経由しない電源短絡経路が形成される。このように、実施の形態1では、寄生ダイオード312a及び寄生ダイオード322aに電流が流れるのではなく、スイッチング素子312及びスイッチング素子322のそれぞれのチャネルに電流が流れることで、電源短絡経路が形成される。 FIG. 5 is a second diagram illustrating a path of a current flowing through power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is positive. In FIG. 5, the power supply voltage polarity is positive, the switching element 312 and the switching element 322 are on, and the switching element 311 and the switching element 321 are off. In this state, a current flows in the order of the AC power supply 1, the reactor 2, the switching element 312, the switching element 322, and the AC power supply 1, and a power supply short-circuit path that does not pass through the smoothing capacitor 4 is formed. As described above, in the first embodiment, a current does not flow through the parasitic diode 312a and the parasitic diode 322a, but a current flows through each channel of the switching element 312 and the switching element 322, thereby forming a power supply short-circuit path. .
 図6は、電源電流Isの絶対値が電流閾値より大きく、かつ、電源電圧極性が負のとき、実施の形態1に係る電力変換装置100に流れる電流の経路を示す第2の図である。図6では、電源電圧極性が負であり、スイッチング素子311及びスイッチング素子321がオンであり、スイッチング素子312及びスイッチング素子322がオフである。この状態では、交流電源1、スイッチング素子321、スイッチング素子311、リアクタ2、交流電源1の順序で電流が流れ、平滑コンデンサ4を経由しない電源短絡経路が形成される。このように、実施の形態1では、寄生ダイオード311a及び寄生ダイオード321aに電流が流れるのではなく、スイッチング素子311及びスイッチング素子321のそれぞれのチャネルに電流が流れることで、電源短絡経路が形成される。 FIG. 6 is a second diagram illustrating a path of a current flowing through power conversion device 100 according to Embodiment 1 when the absolute value of power supply current Is is larger than the current threshold value and the power supply voltage polarity is negative. In FIG. 6, the power supply voltage polarity is negative, the switching element 311 and the switching element 321 are on, and the switching element 312 and the switching element 322 are off. In this state, current flows in the order of the AC power supply 1, the switching element 321, the switching element 311, the reactor 2, and the AC power supply 1, and a power supply short-circuit path that does not pass through the smoothing capacitor 4 is formed. As described above, in the first embodiment, a current does not flow through the parasitic diode 311a and the parasitic diode 321a, but a current flows through each channel of the switching element 311 and the switching element 321, thereby forming a power supply short-circuit path. .
 制御部10は、以上に述べた電流経路の切替えを制御することで、電源電流Is及び母線電圧Vdcの値を制御できる。電力変換装置100は、電源電圧極性が正のときは図3に示す負荷電力供給モードと図5に示す電源短絡モードとを連続的に切り替え、電源電圧極性が負のときは図4に示す負荷電力供給モードと図6に示す電源短絡モードとを連続的に切り替えることで、母線電圧Vdcの上昇、電源電流Isの同期整流などの動作を実現する。具体的には、制御部10は、PWMによるスイッチング動作を行うスイッチング素子311,312のスイッチング周波数を、電源電圧Vsの極性に応じたスイッチング動作を行うスイッチング素子321,322のスイッチング周波数よりも高くして、スイッチング素子311,312,321,322のオンオフを制御する。以降の説明において、スイッチング素子311,312,321,322を区別しない場合は単にスイッチング素子と称することがある。同様に、寄生ダイオード311a,312a,321a,322aを区別しない場合は単に寄生ダイオードと称することがある。 The control unit 10 can control the values of the power supply current Is and the bus voltage Vdc by controlling the switching of the current paths described above. The power converter 100 continuously switches between the load power supply mode shown in FIG. 3 and the power supply short-circuit mode shown in FIG. 5 when the power supply voltage polarity is positive, and the load shown in FIG. 4 when the power supply voltage polarity is negative. By continuously switching between the power supply mode and the power supply short-circuit mode shown in FIG. 6, operations such as an increase in the bus voltage Vdc and synchronous rectification of the power supply current Is are realized. Specifically, the control unit 10 sets the switching frequency of the switching elements 311 and 312 performing the switching operation by PWM higher than the switching frequency of the switching elements 321 and 322 performing the switching operation according to the polarity of the power supply voltage Vs. Thus, the on / off of the switching elements 311, 312, 321, 322 is controlled. In the following description, when the switching elements 311, 312, 321 and 322 are not distinguished, they may be simply referred to as switching elements. Similarly, when the parasitic diodes 311a, 312a, 321a, and 322a are not distinguished, they may be simply referred to as parasitic diodes.
 次に、制御部10が、スイッチング素子をオンオフするタイミングについて説明する。図7は、実施の形態1に係る電力変換装置100において制御部10がスイッチング素子をオンするタイミングを示す図である。図7において横軸は時間である。図7において、Vsは電源電圧検出部5で検出される電源電圧Vsであり、Isは電源電流検出部6で検出される電源電流Isである。図7では、スイッチング素子311,312が、電源電流Isの極性に応じてオンオフが制御される電流同期のスイッチング素子であることを示し、スイッチング素子321,322が、電源電圧Vsの極性に応じてオンオフが制御される電圧同期のスイッチング素子であることを示す。また、図7において、Ithは電流閾値を示す。なお、図7では交流電源1から出力される交流電力の1周期を示しているが、制御部10は、他の周期においても図7に示す制御と同様の制御を行うものとする。 Next, the timing at which the control unit 10 turns on and off the switching element will be described. FIG. 7 is a diagram showing the timing at which the control unit 10 turns on the switching element in the power conversion device 100 according to the first embodiment. In FIG. 7, the horizontal axis is time. In FIG. 7, Vs is the power supply voltage Vs detected by the power supply voltage detector 5, and Is is the power supply current Is detected by the power supply current detector 6. FIG. 7 shows that the switching elements 311 and 312 are current-synchronous switching elements whose on and off are controlled in accordance with the polarity of the power supply current Is, and the switching elements 321 and 322 correspond to the polarity of the power supply voltage Vs. Indicates that the switching element is a voltage-synchronized switching element whose on / off is controlled. In FIG. 7, Ith represents a current threshold. Although FIG. 7 illustrates one cycle of the AC power output from the AC power supply 1, the control unit 10 performs control similar to the control illustrated in FIG. 7 in other cycles.
 制御部10は、電源電圧極性が正の場合、スイッチング素子322をオンし、スイッチング素子321をオフする。また、制御部10は、電源電圧極性が負の場合、スイッチング素子321をオンし、スイッチング素子322をオフする。なお、図7では、スイッチング素子322がオンからオフになるタイミングと、スイッチング素子321がオフからオンになるタイミングとが同じタイミングであるが、これに限定されない。制御部10は、スイッチング素子322がオンからオフになるタイミングと、スイッチング素子321がオフからオンになるタイミングとの間に、スイッチング素子321,322がともにオフになるデッドタイムを設けてもよい。同様に、制御部10は、スイッチング素子321がオンからオフになるタイミングと、スイッチング素子322がオフからオンになるタイミングとの間に、スイッチング素子321,322がともにオフになるデッドタイムを設けてもよい。 When the power supply voltage polarity is positive, the control unit 10 turns on the switching element 322 and turns off the switching element 321. When the power supply voltage polarity is negative, the control unit 10 turns on the switching element 321 and turns off the switching element 322. In FIG. 7, the timing at which the switching element 322 turns from on to off and the timing at which the switching element 321 turns from off to on are the same, but the present invention is not limited to this. The control unit 10 may provide a dead time during which both the switching elements 321 and 322 are turned off between the timing when the switching element 322 is turned off from on and the timing when the switching element 321 is turned on from off. Similarly, the control unit 10 provides a dead time during which both the switching elements 321 and 322 are turned off between the timing when the switching element 321 is turned off from on and the timing when the switching element 322 is turned on from off. Is also good.
 制御部10は、電源電圧極性が正の場合、電源電流Isの絶対値が電流閾値Ith以上になると、スイッチング素子311をオンする。その後、制御部10は、電源電流Isの絶対値が小さくなり、電源電流Isの絶対値が電流閾値Ithより小さくなると、スイッチング素子311をオフする。また、制御部10は、電源電圧極性が負の場合、電源電流Isの絶対値が電流閾値Ith以上になると、スイッチング素子312をオンする。その後、制御部10は、電源電流Isの絶対値が小さくなり、電源電流Isの絶対値が電流閾値Ithより小さくなると、スイッチング素子312をオフする。 The control unit 10 turns on the switching element 311 when the power supply voltage polarity is positive and the absolute value of the power supply current Is becomes equal to or greater than the current threshold value Ith. Thereafter, when the absolute value of the power supply current Is becomes smaller and the absolute value of the power supply current Is becomes smaller than the current threshold value Ith, the control unit 10 turns off the switching element 311. When the power supply voltage polarity is negative and the absolute value of the power supply current Is becomes equal to or greater than the current threshold Ith, the control unit 10 turns on the switching element 312. Thereafter, when the absolute value of the power supply current Is decreases and the absolute value of the power supply current Is becomes smaller than the current threshold value Ith, the control unit 10 turns off the switching element 312.
 制御部10は、電源電流Isの絶対値が電流閾値Ith以下の場合には、上側スイッチング素子のスイッチング素子311及びスイッチング素子321が同時にオンしないように制御し、また、下側スイッチング素子のスイッチング素子312及びスイッチング素子322が同時にオンしないように制御する。これにより、制御部10は、電力変換装置100においてコンデンサ短絡を防止できる。 When the absolute value of the power supply current Is is equal to or smaller than the current threshold value Ith, the control unit 10 controls the switching elements 311 and 321 of the upper switching element so as not to be turned on at the same time. Control is performed so that the switch 312 and the switching element 322 are not turned on at the same time. Thereby, control unit 10 can prevent a capacitor short circuit in power conversion device 100.
 ここで、電力変換装置100は、実際には、電源電流Isを連続して検出しているのではなく、制御周期毎に電源電流Isを検出する。すなわち、電力変換装置100は、制御周期単位の電源電流Isの検出では、電源電流Isが電流閾値Ithになる瞬間を正確に検出できない場合がある。そのため、本実施の形態では、制御部10は、電源電流検出部6で前回検出された電流値である第1の電流値と電源電流検出部6で今回検出した電流値である第2の電流値とを用いて、電源電流検出部6で次に検出される電流値の予測値を算出する。前回検出された第1の電流値は、電源電流検出部6で過去に検出された電流値であり、今回検出された第2の電流値は、電源電流検出部6で新たに検出された電流値である。制御部10は、算出した予測値に応じて、スイッチング素子311,312のオンオフを制御する。このように、制御部10は、電源電流検出部6で検出された過去の電流値を用いてスイッチング素子311,312のオンオフを制御する。 Here, the power conversion device 100 does not actually detect the power supply current Is continuously, but detects the power supply current Is in each control cycle. That is, the power conversion device 100 may not be able to accurately detect the moment when the power supply current Is becomes the current threshold value Ith in the detection of the power supply current Is in control cycle units. Therefore, in the present embodiment, control unit 10 determines the first current value which is the current value detected last time by power supply current detection unit 6 and the second current value which is the current value detected by power supply current detection unit 6 this time. Using the value, the predicted value of the current value detected next by the power supply current detection unit 6 is calculated. The first current value detected last time is the current value detected in the past by the power supply current detection unit 6, and the second current value detected this time is the current value detected newly by the power supply current detection unit 6. Value. The control unit 10 controls on / off of the switching elements 311 and 312 according to the calculated predicted value. As described above, the control unit 10 controls on / off of the switching elements 311 and 312 using the past current value detected by the power supply current detection unit 6.
 図8は、実施の形態1に係る電力変換装置100の制御部10が、電源電流検出部6で次に検出される電流値の予測値を算出する処理を示す図である。また、図8は、図7に示す電源電流Isに対して、電力変換装置100に流れる実際の電源電流と、電力変換装置100で検出される電源電流Isとを示している。図8は、図7に示す電源電流Isのうち、電源電流Isの極性が正の部分を示している。図8において、横軸は時間を示し、縦軸は電流値を示す。図8において、Ithは電流閾値を示す。Id(n-1)は、n-1回目の制御タイミングの際に電源電流検出部6で検出された電流値であり、前述の第1の電流値に相当する。Id(n)は、n回目の制御タイミングの際に電源電流検出部6で検出された電流値であり、前述の第2の電流値に相当する。Ie(n)は、n回目の制御タイミングの時点で制御部10が電源電流検出部6で次に検出される電流値を予測したものであり、前述の予測値に相当する。Tsは、電源電流検出部6が電流値を検出する周期であり、前述の制御周期である。このような場合、制御部10は、次の式(1)を用いて予測値Ie(n)を算出することができる。 FIG. 8 is a diagram illustrating a process in which the control unit 10 of the power conversion device 100 according to Embodiment 1 calculates a predicted value of a current value detected next by the power supply current detection unit 6. FIG. 8 shows the actual power supply current flowing through the power conversion device 100 and the power supply current Is detected by the power conversion device 100 with respect to the power supply current Is shown in FIG. FIG. 8 shows a portion of the power supply current Is shown in FIG. 7 where the polarity of the power supply current Is is positive. In FIG. 8, the horizontal axis represents time, and the vertical axis represents current value. In FIG. 8, Ith indicates a current threshold. Id (n-1) is a current value detected by the power supply current detection unit 6 at the (n-1) th control timing, and corresponds to the above-described first current value. Id (n) is a current value detected by the power supply current detection unit 6 at the time of the n-th control timing, and corresponds to the above-described second current value. Ie (n) is obtained by the control unit 10 predicting the current value detected next by the power supply current detection unit 6 at the time of the n-th control timing, and corresponds to the above-described predicted value. Ts is a cycle in which the power supply current detector 6 detects a current value, and is the above-described control cycle. In such a case, the control unit 10 can calculate the predicted value Ie (n) using the following equation (1).
  Ie(n)=Id(n)+((Id(n)-Id(n-1))/Ts)×Ts …(1) {Ie (n) = Id (n) + ((Id (n) -Id (n-1)) / Ts) × Ts} (1)
 式(1)において、((Id(n)-Id(n-1))/Ts)は、n-1回目の制御タイミングからn回目の制御タイミングまでの期間における電源電流Isの変化を直線近似したときの傾きである。制御部10は、電流値Id(n-1)、電流値Id(n)、及び電源電流検出部6が電流値を検出する制御周期Tsを用いて算出した値を、電流値Id(n)に加算して予測値Ie(n)を算出する。なお、式(1)については、次の式(2)のように変形させることができる。 In equation (1), ((Id (n) −Id (n−1)) / Ts) is a linear approximation of the change in the power supply current Is during the period from the (n−1) th control timing to the nth control timing. It is the inclination when doing. The control unit 10 calculates a value calculated using the current value Id (n-1), the current value Id (n), and the control cycle Ts in which the power supply current detection unit 6 detects the current value, by using the current value Id (n). To calculate the predicted value Ie (n). Equation (1) can be modified as in the following equation (2).
  Ie(n)=Id(n)+(Id(n)-Id(n-1)) …(2) {Ie (n) = Id (n) + (Id (n) -Id (n-1))} (2)
 すなわち、制御部10は、電流値Id(n)に、電流値Id(n)と電流値Id(n-1)との差分を加算することで、予測値Ie(n)を算出することができる。なお、制御部10は、式(1)または式(2)の右辺のように計算して求めた値に対して、規定された係数を乗算したものを予測値Ie(n)としてもよい。これにより、制御部10は、電源電流Isの変化が急峻な場合にも対応することができる。 That is, the control unit 10 can calculate the predicted value Ie (n) by adding the difference between the current value Id (n) and the current value Id (n-1) to the current value Id (n). it can. Note that the control unit 10 may multiply a value calculated by the right side of Expression (1) or Expression (2) by a specified coefficient as the predicted value Ie (n). Thereby, the control unit 10 can cope with a case where the change of the power supply current Is is sharp.
 図9は、実施の形態1に係る電力変換装置100の制御部10が電源電流Isの極性に応じてオンオフを制御するスイッチング素子311,312に対する処理を示すフローチャートである。一例として、電源電流Isの極性が正の場合について説明する。制御部10は、予測値Ie(n)を算出する(ステップS1)。制御部10における予測値Ie(n)の算出方法は前述のとおりである。制御部10は、予測値Ie(n)の絶対値と電流閾値Ithとを比較する(ステップS2)。制御部10は、予測値Ie(n)の絶対値が電流閾値Ith以下の場合(ステップS3:Yes)、次に電源電流検出部6が検出する電流値の絶対値は電流閾値Ith以下であるとして、電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子311をオフにする(ステップS4)。制御部10は、予測値Ie(n)の絶対値が電流閾値Ithより大きい場合(ステップS3:No)、次に電源電流検出部6が検出する電流値の絶対値は電流閾値Ithより大きいとして、電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子311をオンのままとする(ステップS5)。制御部10は、電源電流Isの極性が負の場合、スイッチング素子312を対象にして、上記同様の処理を行う。なお、制御周期Tsについては、制御部10で算出される予測値Ie(n)が、-Ith≦Ie(n)≦Ithになる程度に電源電流検出部6が電流値を検出する間隔とする。 FIG. 9 is a flowchart showing a process performed by the control unit 10 of the power converter 100 according to Embodiment 1 for the switching elements 311 and 312 that control on / off in accordance with the polarity of the power supply current Is. As an example, a case where the polarity of the power supply current Is is positive will be described. The control unit 10 calculates a predicted value Ie (n) (Step S1). The method of calculating the predicted value Ie (n) in the control unit 10 is as described above. The control unit 10 compares the absolute value of the predicted value Ie (n) with the current threshold value Ith (Step S2). When the absolute value of the predicted value Ie (n) is equal to or less than the current threshold value Ith (Step S3: Yes), the control unit 10 determines that the absolute value of the current value detected by the power supply current detection unit 6 is equal to or less than the current threshold value Ith. Then, among the switching elements controlled according to the polarity of the current, the switching element 311 that is turned on is turned off (step S4). When the absolute value of the predicted value Ie (n) is larger than the current threshold Ith (Step S3: No), the control unit 10 determines that the absolute value of the current value detected by the power supply current detector 6 is larger than the current threshold Ith. The switching element 311 which is turned on among the switching elements controlled in accordance with the polarity of the current is kept on (step S5). When the polarity of the power supply current Is is negative, the control unit 10 performs the same processing on the switching element 312 as described above. The control cycle Ts is an interval at which the power supply current detector 6 detects a current value such that the predicted value Ie (n) calculated by the controller 10 satisfies −Ith ≦ Ie (n) ≦ Ith. .
 制御部10は、次に電源電流検出部6で検出される電流値の予測値Ie(n)を算出することによって、予測値Ie(n)の絶対値が電流閾値Ith以下になる場合、実際に電力変換装置100に流れる電流の電流値の絶対値が電流閾値Ithになる前にスイッチング素子をオフすることができる。すなわち、電力変換装置100は、制御遅延によるスイッチング素子をオフするタイミングが遅れることによる、平滑コンデンサ4から交流電源1への逆流電流の発生を防止することができる。そのため、電力変換装置100を使用するユーザは、電流閾値Ithを従来よりも小さな値に設定することができる。これにより、電力変換装置100は、高精度な同期整流動作を実現することができる。また、電力変換装置100は、電流の極性に応じて制御するスイッチング素子311,312をオンする期間を長くすることができ、効率の低下を抑制し、損失を低減して高効率なシステムを得ることができる。 The control unit 10 calculates the predicted value Ie (n) of the current value detected by the power supply current detection unit 6 so that when the absolute value of the predicted value Ie (n) becomes equal to or smaller than the current threshold value Ith, The switching element can be turned off before the absolute value of the current value of the current flowing through the power converter 100 reaches the current threshold value Ith. That is, power conversion device 100 can prevent generation of a reverse current from smoothing capacitor 4 to AC power supply 1 due to a delay in turning off the switching element due to the control delay. Therefore, the user using the power converter 100 can set the current threshold value Ith to a smaller value than before. Thereby, the power conversion device 100 can realize a highly accurate synchronous rectification operation. In addition, the power conversion device 100 can lengthen the period during which the switching elements 311 and 312 that are controlled according to the polarity of the current are on, suppress a decrease in efficiency, and reduce loss to obtain a highly efficient system. be able to.
 なお、制御部10は、算出した予測値Ie(n)の絶対値と電流閾値Ithとを比較してスイッチング素子311,312のオンオフを制御していたが、これに限定されない。制御部10は、頻繁に電源電流検出部6が電流値を検出するような制御周期Tsであれば、算出した予測値Ie(n)がゼロになったか否かでスイッチング素子311,312のオンオフを制御してもよい。具体的には、制御部10は、算出した予測値Ie(n)がゼロになった場合、または電流値Id(n)と異なる極性になった場合、電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子をオフにする。予測値Ie(n)が電流値Id(n)と異なる極性になった場合とは、電流値Id(n)が正で予測値Ie(n)が負の場合、または、電流値Id(n)が負で予測値Ie(n)が正の場合である。 The control unit 10 controls on / off of the switching elements 311 and 312 by comparing the calculated absolute value of the predicted value Ie (n) with the current threshold value Ith, but is not limited thereto. When the control period Ts is such that the power supply current detection unit 6 frequently detects the current value, the control unit 10 turns on / off the switching elements 311 and 312 based on whether the calculated predicted value Ie (n) has become zero. May be controlled. Specifically, when the calculated predicted value Ie (n) becomes zero or has a polarity different from the current value Id (n), the control unit 10 performs control according to the polarity of the current. The switching elements that are turned on among the switching elements are turned off. The case where the predicted value Ie (n) has a different polarity from the current value Id (n) means that the current value Id (n) is positive and the predicted value Ie (n) is negative, or that the current value Id (n) is negative. ) Is negative and the predicted value Ie (n) is positive.
 ここで、スイッチング素子の構成について説明する。電力変換装置100において、スイッチング素子のスイッチング速度を速くする方法の1つに、スイッチング素子のゲート抵抗を小さくする方法が挙げられる。ゲート抵抗が小さくなる程、ゲート入力容量への充放電時間が短くなり、ターンオン期間及びターンオフ期間が短くなるため、スイッチング速度が速くなる。 Here, the configuration of the switching element will be described. One method of increasing the switching speed of the switching element in the power conversion device 100 is a method of reducing the gate resistance of the switching element. As the gate resistance decreases, the charging / discharging time for the gate input capacitance becomes shorter, and the turn-on period and the turn-off period become shorter, so that the switching speed becomes faster.
 しかしながら、ゲート抵抗を小さくすることでスイッチング損失を低減するには限界がある。そこで、スイッチング素子を、GaNまたはSiCといったWBG半導体で構成することにより、1回のスイッチング当りの損失を更に抑制することができ、より一層効率が向上し、かつ、高周波スイッチングが可能となる。また、高周波スイッチングが可能となることで、リアクタ2の小型化が可能となり、電力変換装置100の小型化及び軽量化が可能となる。また、スイッチング素子にWBG半導体を用いることにより、スイッチング速度が向上して、スイッチング損失が抑制されるため、スイッチング素子が正常な動作を継続できるような放熱対策を簡素化できる。また、スイッチング素子にWBG半導体を用いることにより、スイッチング周波数を十分に高い値、例えば16kHz以上にすることができるため、スイッチングに起因する騒音を抑制できる。 However, there is a limit to reducing the switching loss by reducing the gate resistance. Therefore, by configuring the switching element with a WBG semiconductor such as GaN or SiC, loss per switching can be further suppressed, efficiency is further improved, and high-frequency switching can be performed. Further, by enabling high-frequency switching, the size of the reactor 2 can be reduced, and the size and weight of the power conversion device 100 can be reduced. In addition, by using a WBG semiconductor for the switching element, the switching speed is improved and the switching loss is suppressed, so that a heat radiation measure that allows the switching element to continue normal operation can be simplified. Further, by using a WBG semiconductor for the switching element, the switching frequency can be set to a sufficiently high value, for example, 16 kHz or more, so that noise due to switching can be suppressed.
 また、GaN半導体は、GaN層と窒化アルミニウムガリウム層との界面に2次元電子ガスが生じ、この2次元電子ガスにより、キャリアの移動度が高い。このため、GaN半導体を用いたスイッチング素子は、高速スイッチングを実現可能である。ここで、交流電源1が、50Hz/60Hzの商用電源である場合、可聴域周波数は、16kHzから20kHzまでの範囲、すなわち商用電源の周波数の266倍から400倍までの範囲となる。GaN半導体は、この可聴域周波数より高い周波数でスイッチングする場合に好適である。半導体材料として主流である珪素(Si)で構成されたスイッチング素子311,312,321,322を、数十kHz以上のスイッチング周波数で駆動した場合、スイッチング損失の比率が大きくなり、放熱対策が必須となる。これに対して、GaN半導体で構成されたスイッチング素子311,312,321,322は、数十kHz以上のスイッチング周波数、具体的には20kHzより高いスイッチング周波数で駆動した場合でも、スイッチング損失が非常に小さい。そのため、放熱対策が不要になり、または放熱対策のために利用される放熱部材のサイズを小型化でき、電力変換装置100の小型化及び軽量化が可能となる。また、高周波スイッチングが可能となることで、リアクタ2の小型化が可能になる。なお、雑音端子電圧規格の測定範囲にスイッチング周波数の1次成分が入らないようにするため、スイッチング周波数は、150kHz以下とすることが好ましい。 In the GaN semiconductor, a two-dimensional electron gas is generated at the interface between the GaN layer and the aluminum gallium nitride layer, and the two-dimensional electron gas has high carrier mobility. Therefore, a switching element using a GaN semiconductor can realize high-speed switching. Here, when the AC power supply 1 is a commercial power supply of 50 Hz / 60 Hz, the audible frequency ranges from 16 kHz to 20 kHz, that is, from 266 times to 400 times the frequency of the commercial power supply. GaN semiconductors are suitable for switching at frequencies higher than the audible frequency. When the switching elements 311, 312, 321, and 322 made of silicon (Si), which is a mainstream semiconductor material, are driven at a switching frequency of several tens of kHz or more, the switching loss ratio increases, and heat dissipation measures are indispensable. Become. On the other hand, the switching elements 311, 312, 321, and 322 made of a GaN semiconductor have extremely low switching loss even when driven at a switching frequency of several tens kHz or more, specifically, a switching frequency higher than 20 kHz. small. Therefore, no heat radiation measures are required, or the size of the heat radiation member used for the heat radiation measures can be reduced, and the power conversion device 100 can be reduced in size and weight. Further, since high-frequency switching becomes possible, the size of the reactor 2 can be reduced. Note that the switching frequency is preferably set to 150 kHz or less so that the primary component of the switching frequency does not fall within the measurement range of the noise terminal voltage standard.
 また、WBG半導体は、Si半導体に比べて静電容量が小さいため、スイッチングに起因するリカバリ電流の発生が少なく、リカバリ電流に起因する損失及びノイズの発生を抑制できるため、高周波スイッチングに適している。 In addition, since the WBG semiconductor has a smaller capacitance than the Si semiconductor, the generation of the recovery current due to the switching is small, and the generation of the loss and the noise due to the recovery current can be suppressed. Therefore, the WBG semiconductor is suitable for high-frequency switching. .
 なお、SiC半導体はGaN半導体に比べてオン抵抗が小さいため、第2のアーム32よりも、スイッチング回数が多い第1のアーム31のスイッチング素子311,312は、GaN半導体で構成し、スイッチング回数が少ない第2のアーム32のスイッチング素子321,322は、SiC半導体で構成してもよい。これにより、SiC半導体及びGaN半導体のそれぞれの特性を最大限に生かすことができる。また、SiC半導体を、第1のアーム31よりも、スイッチング回数が少ない第2のアーム32のスイッチング素子321,322に利用することで、スイッチング素子321,322の損失の内、導通損失が占める割合が多くなり、ターンオン損失及びターンオフ損失が小さくなる。従って、スイッチング素子321,322のスイッチングに伴う発熱の上昇が抑制され、第2のアーム32を構成するスイッチング素子321,322のチップ面積を相対的に小さくでき、チップ製造時の歩留まりが低いSiC半導体を有効に活用できる。 Since the ON resistance of the SiC semiconductor is smaller than that of the GaN semiconductor, the switching elements 311 and 312 of the first arm 31 having a larger number of switching times than the second arm 32 are formed of a GaN semiconductor. The switching elements 321 and 322 of the small second arm 32 may be made of a SiC semiconductor. Thereby, the characteristics of each of the SiC semiconductor and the GaN semiconductor can be maximized. Further, by using the SiC semiconductor for the switching elements 321 and 322 of the second arm 32 having a smaller number of switching times than the first arm 31, the ratio of the conduction loss to the loss of the switching elements 321 and 322. And the turn-on loss and the turn-off loss are reduced. Therefore, an increase in heat generation due to the switching of the switching elements 321 and 322 is suppressed, the chip area of the switching elements 321 and 322 constituting the second arm 32 can be relatively reduced, and the yield of the SiC semiconductor during chip manufacturing is low. Can be used effectively.
 また、スイッチング回数が少ない第2のアーム32のスイッチング素子321,322には、スーパージャンクション(Super Junction:SJ)-MOSFETを用いてもよい。SJ-MOSFETを用いることにより、SJ-MOSFETのメリットである低オン抵抗を生かしつつ、静電容量が高くリカバリが発生しやすいというデメリットを抑制できる。また、SJ-MOSFETを用いることにより、WBG半導体を用いる場合に比べて、第2のアーム32の製造コストを低減できる。 {Circle around (2)} The switching elements 321 and 322 of the second arm 32 having a small number of switching times may use a super junction (Super Junction: SJ) -MOSFET. By using the SJ-MOSFET, it is possible to suppress the demerit that the capacitance is high and the recovery is likely to occur while taking advantage of the low on-resistance, which is an advantage of the SJ-MOSFET. Further, by using the SJ-MOSFET, the manufacturing cost of the second arm 32 can be reduced as compared with the case where a WBG semiconductor is used.
 また、WBG半導体は、Si半導体に比べて耐熱性が高く、ジャンクション温度が高温でも動作が可能である。そのため、WBG半導体を用いることにより、第1のアーム31及び第2のアーム32を、熱抵抗が大きい小型のチップでも構成できる。特に、チップ製造時の歩留まりが低いSiC半導体は、小型のチップに利用した方が低コスト化を実現できる。 W Further, the WBG semiconductor has higher heat resistance than the Si semiconductor, and can operate even at a high junction temperature. Therefore, by using a WBG semiconductor, the first arm 31 and the second arm 32 can be configured with a small chip having high thermal resistance. In particular, a SiC semiconductor having a low yield at the time of manufacturing a chip can be reduced in cost by using it for a small chip.
 また、WBG半導体は、100kHz程度の高周波で駆動した場合でも、スイッチング素子で発生する損失の増加が抑制されるため、リアクタ2の小型化による損失低減効果が大きくなり、広い出力帯域、すなわち広い負荷条件において、高効率なコンバータを実現できる。 Further, even when the WBG semiconductor is driven at a high frequency of about 100 kHz, an increase in loss occurring in the switching element is suppressed, so that the loss reduction effect due to the downsizing of the reactor 2 is increased, and a wide output band, that is, a wide load. Under the conditions, a highly efficient converter can be realized.
 また、WBG半導体は、Si半導体に比べて耐熱性が高く、アーム間の損失の偏りによるスイッチングの発熱許容レベルが高いため、高周波駆動によるスイッチング損失が発生する第1のアーム31に好適である。 The WBG semiconductor has higher heat resistance than the Si semiconductor, and has a higher allowable level of switching heat generation due to the bias of loss between the arms. Therefore, the WBG semiconductor is suitable for the first arm 31 in which switching loss occurs due to high-frequency driving.
 つづいて、電力変換装置100が備える制御部10のハードウェア構成について説明する。図10は、実施の形態1に係る電力変換装置100が備える制御部10を実現するハードウェア構成の一例を示す図である。制御部10は、プロセッサ201及びメモリ202により実現される。 Next, the hardware configuration of the control unit 10 included in the power conversion device 100 will be described. FIG. 10 is a diagram illustrating an example of a hardware configuration that implements the control unit 10 included in the power conversion device 100 according to the first embodiment. The control unit 10 is realized by the processor 201 and the memory 202.
 プロセッサ201は、CPU(Central Processing Unit、中央処理装置、処理装置、演算装置、マイクロプロセッサ、マイクロコンピュータ、プロセッサ、DSP(Digital Signal Processor)ともいう)、またはシステムLSI(Large Scale Integration)である。メモリ202は、RAM(Random Access Memory)、ROM(Read Only Memory)、フラッシュメモリー、EPROM(Erasable Programmable Read Only Memory)、EEPROM(登録商標)(Electrically Erasable Programmable Read-Only Memory)といった不揮発性または揮発性の半導体メモリを例示できる。またメモリ202は、これらに限定されず、磁気ディスク、光ディスク、コンパクトディスク、ミニディスク、またはDVD(Digital Versatile Disc)でもよい。 The processor 201 is a CPU (Central Processing Unit), a central processing unit, a processing device, an arithmetic unit, a microprocessor, a microcomputer, a processor, a DSP (Digital Signal Processor), or a system LSI (Large Scale Integration). The memory 202 is nonvolatile or volatile such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (registered trademark) (Electrically Erasable Programmable Read-Only Memory). Can be exemplified. The memory 202 is not limited to these, and may be a magnetic disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).
 以上説明したように、本実施の形態によれば、電力変換装置100において、制御部10は、電源電流検出部6で前回検出された電流値Id(n-1)と電源電流検出部6で今回検出した電流値Id(n)とを用いて、電源電流検出部6で次に検出される電流値の予測値Ie(n)を算出する。制御部10は、算出した予測値Ie(n)に応じて、スイッチング素子311,312のオンオフを制御することとした。これにより、電力変換装置100は、逆流電流の発生を抑制しつつ、同期整流動作において効率を向上することができる。 As described above, according to the present embodiment, in power conversion device 100, control unit 10 determines whether current value Id (n−1) detected by power supply current detection unit 6 last time and power supply current detection unit 6 Using the current value Id (n) detected this time, the predicted value Ie (n) of the current value detected next by the power supply current detector 6 is calculated. The control unit 10 controls on / off of the switching elements 311 and 312 according to the calculated predicted value Ie (n). Thereby, the power conversion device 100 can improve the efficiency in the synchronous rectification operation while suppressing the generation of the backflow current.
 図8に示すように、制御部10は、電流値の極性が正の場合において、電流値が増加中であっても、予測値Ie(n)を算出してもよい。同様に、制御部10は、電流値の極性が負の場合において、電流値が減少中であっても、予測値Ie(n)を算出してもよい。 As shown in FIG. 8, when the polarity of the current value is positive, the control unit 10 may calculate the predicted value Ie (n) even when the current value is increasing. Similarly, when the polarity of the current value is negative, the control unit 10 may calculate the predicted value Ie (n) even when the current value is decreasing.
 なお、制御部10は、図8の例では、一定間隔の制御周期Tsで予測値Ie(n)を算出していたが、これに限定されない。図8の例では、電流値が増加中の状況では、電源電流検出部6で次に検出される電流値の絶対値が電流閾値Ith以下になることはないと想定される。すなわち、制御部10は、電流値が増加中の状況では、頻繁に予測値Ie(n)を算出する必要はない。そのため、制御部10は、電流値の極性が正の場合、電流値が増加中に予測値Ie(n)を算出する頻度より、電流値が減少中に予測値Ie(n)を算出する頻度を高くする。同様に、制御部10は、電流値の極性が負の場合、電流値が減少中に予測値Ie(n)を算出する頻度より、電流値が増加中に予測値Ie(n)を算出する頻度を高くする。これにより、制御部10は、処理負荷を低減することができる。 In the example of FIG. 8, the control unit 10 calculates the predicted value Ie (n) in the control cycle Ts at a fixed interval, but the present invention is not limited to this. In the example of FIG. 8, it is assumed that in a situation where the current value is increasing, the absolute value of the current value detected next by the power supply current detection unit 6 does not become less than or equal to the current threshold value Ith. That is, the control unit 10 does not need to frequently calculate the predicted value Ie (n) in a situation where the current value is increasing. Therefore, when the polarity of the current value is positive, the control unit 10 calculates the predicted value Ie (n) while the current value is decreasing, rather than the frequency of calculating the predicted value Ie (n) while the current value is increasing. Higher. Similarly, when the polarity of the current value is negative, the control unit 10 calculates the predicted value Ie (n) while the current value is increasing from the frequency of calculating the predicted value Ie (n) while the current value is decreasing. Increase frequency. Thereby, the control unit 10 can reduce the processing load.
 また、制御部10は、電流値Id(n)がゼロのときは予測値Ie(n)を算出しなくてもよい。予測値Ie(n)の絶対値が既に電流閾値Ith以内のため、制御部10においてスイッチング素子をオフする処理に影響しないためである。この場合も同様に、制御部10は、処理負荷を低減することができる。 The control unit 10 does not have to calculate the predicted value Ie (n) when the current value Id (n) is zero. This is because the absolute value of the predicted value Ie (n) is already within the current threshold value Ith, so that the control unit 10 does not affect the process of turning off the switching element. In this case, similarly, the control unit 10 can reduce the processing load.
 また、電力変換装置100で使用されるスイッチング素子としてMOSFETを使用する場合について説明したが、一例であり、これに限定されない。スイッチング処理の遅延によって逆流電流が発生する可能性のあるスイッチング素子であれば、MOSFET以外のスイッチング素子にも、本実施の形態の処理を適用することが可能である。 Also, the case where the MOSFET is used as the switching element used in the power converter 100 has been described, but this is an example, and the present invention is not limited to this. The processing of the present embodiment can be applied to switching elements other than MOSFETs as long as the switching element may cause a reverse current due to a delay in the switching processing.
 また、本実施の形態では、電力変換装置100の制御部10が、電源電流検出部6で検出された電流値を用いて次に電源電流検出部6で検出される電流値を予測していたが、これに限定されない。制御部10は、同様の手法を用いて、電源電圧検出部5で検出された電圧値を用いて次に電源電圧検出部5で検出される電圧値を予測することも可能である。 Further, in the present embodiment, control unit 10 of power conversion device 100 predicts the current value detected by power supply current detection unit 6 using the current value detected by power supply current detection unit 6. However, the present invention is not limited to this. The control unit 10 can also predict the next voltage value detected by the power supply voltage detection unit 5 using the voltage value detected by the power supply voltage detection unit 5 using the same method.
 なお、本実施の形態では、制御部10は、電源電圧Vsの極性に応じてスイッチング素子321,322のオンオフを制御し、電源電流Isの極性に応じてスイッチング素子311,312のオンオフを制御していたが、これに限定されない。制御部10は、電源電圧Vsの極性に応じてスイッチング素子311,312のオンオフを制御し、電源電流Isの極性に応じてスイッチング素子321,322のオンオフを制御してもよい。 In the present embodiment, the control unit 10 controls on / off of the switching elements 321 and 322 in accordance with the polarity of the power supply voltage Vs, and controls on / off of the switching elements 311 and 312 in accordance with the polarity of the power supply current Is. But not limited to this. The control unit 10 may control on / off of the switching elements 311 and 312 according to the polarity of the power supply voltage Vs, and may control on / off of the switching elements 321 and 322 according to the polarity of the power supply current Is.
実施の形態2.
 実施の形態1では、電力変換装置100において、制御部10は、算出した予測値Ie(n)に応じてスイッチング素子311,312のオンオフを制御していた。そのため、制御部10は、実際に電力変換装置100に流れる電流の電流値の絶対値が電流閾値Ithより大きい場合でも、早めにスイッチング素子311,312をオフしてしまうことがあった。実施の形態2では、制御部10は、電力変換装置100に流れる電流の電流値の絶対値が電流閾値Ithになる時間を推定し、推定した時間でスイッチング素子311,312をオフする。
Embodiment 2 FIG.
In the first embodiment, in power conversion device 100, control unit 10 controls on / off of switching elements 311 and 312 according to calculated predicted value Ie (n). Therefore, even when the absolute value of the current value of the current actually flowing to the power conversion device 100 is larger than the current threshold value Ith, the control unit 10 sometimes turns off the switching elements 311 and 312 early. In the second embodiment, control unit 10 estimates the time at which the absolute value of the current value of the current flowing through power conversion device 100 reaches current threshold Ith, and turns off switching elements 311 and 312 at the estimated time.
 実施の形態2において、電力変換装置100の構成は、図1に示す実施の形態1のときの構成と同様である。実施の形態2では、制御部10は、予測値Ie(n)の絶対値が電流閾値Ith以上になった場合、予測値Ie(n)の絶対値が電流閾値Ithと同一の場合を除いて、予測値Ie(n)の絶対値が電流閾値Ithになる時間を推定する。実施の形態1で説明した式(1)において、予測値Ie(n)を電流閾値Ithに置き換え、経過時間を示す最後の制御周期Tsを予測値Ie(n)が電流閾値Ithになる時間を示す推定時間Tithに置き換えると、次の式(3)のようになる。 に お い て In the second embodiment, the configuration of power conversion device 100 is the same as the configuration in the first embodiment shown in FIG. In the second embodiment, when the absolute value of the predicted value Ie (n) is equal to or larger than the current threshold value Ith, the control unit 10 excludes the case where the absolute value of the predicted value Ie (n) is the same as the current threshold value Ith. , The time when the absolute value of the predicted value Ie (n) becomes the current threshold value Ith. In equation (1) described in the first embodiment, the predicted value Ie (n) is replaced with the current threshold value Ith, and the last control cycle Ts indicating the elapsed time is determined by the time when the predicted value Ie (n) becomes the current threshold value Ith. When the estimated time Tith is replaced with the estimated time Tith, the following equation (3) is obtained.
  Ith=Id(n)+((Id(n)-Id(n-1))/Ts)×Tith …(3) {Ith = Id (n) + ((Id (n) -Id (n-1)) / Ts) × Tith} (3)
 式(3)から、推定時間Tithを求める式(4)を得ることができる。 式 From equation (3), equation (4) for obtaining estimated time Tith can be obtained.
  Tith=((Id(n)-Ith)/(Id(n-1)-Id(n)))×Ts …(4) {Tith = ((Id (n) −Ith) / (Id (n−1) −Id (n))) × Ts} (4)
 制御部10は、予測値Ie(n)の絶対値が電流閾値Ith以下になった場合、n回目の制御タイミングの時点から推定時間Tithが経過した後、電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子をオフする制御を行う。または、制御部10は、予測値Ie(n)の絶対値が電流閾値Ith以下になった場合、n回目の制御タイミングの時点から推定時間Tithまでに、電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子をオフする制御を行う。図11は、実施の形態2に係る電力変換装置100の制御部10がスイッチング素子をオンするタイミングを示す図である。制御部10は、図11に示すタイミング、すなわちn回目の制御タイミングの時点から推定時間Tithが経過した後にスイッチング素子をオフにできるように、例えば、制御周期Tsを生成する制御信号を用いる。制御部10は、例えば、制御周期Tsをカウントするスイッチング用のタイマを用いて制御信号を生成する。制御部10は、例えば、検出された電流値からコンペアマッチ用電源電流を生成し、コンペアマッチ用電源電流と制御信号とを用いてコンペアマッチを行う。コンペアマッチ用電源電流は、電源電流Isが増加中は電流値が制御信号と交差しないレベルに設定された信号である。制御部10は、コンペアマッチ用電源電流と制御信号とが重なるタイミングで、スイッチング素子311をオフする。制御部10は、電流値が正の極性の場合、電流値が増加する間はコンペアマッチを行わないようにしてもよい。 When the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith, the control unit 10 performs control according to the polarity of the current after the estimated time Tith has elapsed from the time of the nth control timing. Control is performed to turn off the switching elements that are turned on among the switching elements. Alternatively, when the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith, the control unit 10 performs control according to the polarity of the current from the time of the nth control timing to the estimated time Tith. Control is performed to turn off the switching elements that are turned on among the switching elements. FIG. 11 is a diagram illustrating a timing at which the control unit 10 of the power conversion device 100 according to Embodiment 2 turns on the switching element. The control unit 10 uses, for example, a control signal for generating a control cycle Ts so that the switching element can be turned off after the estimated time Tith has elapsed from the timing shown in FIG. 11, that is, the time point of the n-th control timing. The control unit 10 generates a control signal using, for example, a switching timer that counts the control cycle Ts. For example, the control unit 10 generates a power supply current for compare match from the detected current value, and performs a compare match using the power supply current for compare match and the control signal. The power supply current for compare match is a signal whose current value is set to a level that does not intersect with the control signal while the power supply current Is is increasing. The control unit 10 turns off the switching element 311 at the timing when the power supply current for compare match and the control signal overlap. When the current value has a positive polarity, the control unit 10 may not perform the compare match while the current value increases.
 なお、制御部10が、予測値Ie(n)の絶対値が電流閾値Ith以下になった場合にTithを算出する例について説明したが、これに限定されない。制御部10は、予測値Ie(n)の絶対値が電流閾値Ith以下になる前からTithを算出してもよい。 In addition, the example in which the control unit 10 calculates Tith when the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith has been described, but the present invention is not limited thereto. The control unit 10 may calculate Tith before the absolute value of the predicted value Ie (n) becomes equal to or less than the current threshold value Ith.
 また、制御部10は、算出した予測値Ie(n)がゼロになったか否かでスイッチング素子311,312のオンオフを制御している場合には、予測値Ie(n)がゼロになる推定時間T0を算出する。具体的には、式(4)において「Ith」を「0」に置き換えることで、次の式(5)を得ることができる。 When the control unit 10 controls the on / off of the switching elements 311 and 312 based on whether the calculated predicted value Ie (n) has become zero, the control unit 10 estimates that the predicted value Ie (n) becomes zero. The time T0 is calculated. Specifically, the following equation (5) can be obtained by replacing "Ith" with "0" in equation (4).
  T0=(Id(n)/(Id(n-1)-Id(n)))×Ts …(5) {T0 = (Id (n) / (Id (n-1) -Id (n))) × Ts} (5)
 以上説明したように、本実施の形態によれば、電力変換装置100において、制御部10は、算出した予測値Ie(n)の絶対値が電流閾値Ith以下になる場合、電力変換装置100に流れる電流の電流値の絶対値が電流閾値Ithになる時間を推定し、推定した時間でスイッチング素子をオフすることとした。これにより、電力変換装置100は、逆流電流の発生を抑制しつつ、実施の形態1と比較してさらに同期整流動作において効率を向上することができる。 As described above, according to the present embodiment, in power conversion device 100, control unit 10 controls power conversion device 100 when the absolute value of calculated predicted value Ie (n) is equal to or smaller than current threshold value Ith. The time at which the absolute value of the current value of the flowing current becomes the current threshold value Ith is estimated, and the switching element is turned off at the estimated time. Thereby, power conversion device 100 can further improve the efficiency in the synchronous rectification operation as compared with the first embodiment, while suppressing the generation of the backflow current.
実施の形態3.
 実施の形態3では、実施の形態1,2で説明した電力変換装置100を備えるモータ駆動装置について説明する。
Embodiment 3 FIG.
In the third embodiment, a motor driving device including the power conversion device 100 described in the first and second embodiments will be described.
 図12は、実施の形態3に係るモータ駆動装置101の構成例を示す図である。モータ駆動装置101は、負荷であるモータ42を駆動する。モータ駆動装置101は、実施の形態1,2の電力変換装置100と、インバータ41と、モータ電流検出部44と、インバータ制御部43とを備える。インバータ41は、電力変換装置100から供給される直流電力を交流電力に変換してモータ42へ出力することにより、モータ42を駆動する。なお、モータ駆動装置101の負荷がモータ42である場合の例を説明しているが、一例であり、インバータ41に接続される機器は、交流電力が入力される機器であればよく、モータ42以外の機器でもよい。 FIG. 12 is a diagram illustrating a configuration example of a motor driving device 101 according to the third embodiment. The motor driving device 101 drives a motor 42 as a load. The motor drive device 101 includes the power conversion devices 100 according to the first and second embodiments, an inverter 41, a motor current detection unit 44, and an inverter control unit 43. The inverter 41 drives the motor 42 by converting DC power supplied from the power converter 100 into AC power and outputting the AC power to the motor 42. Although the example in which the load of the motor driving device 101 is the motor 42 has been described, this is an example, and the device connected to the inverter 41 may be a device to which AC power is input. Other devices may be used.
 インバータ41は、IGBT(Insulated Gate Bipolar Transistor)をはじめとするスイッチング素子を、3相ブリッジ構成または2相ブリッジ構成とした回路である。インバータ41に用いられるスイッチング素子は、IGBTに限定されず、WBG半導体で構成されたスイッチング素子、IGCT(Integrated Gate Commutated Thyristor)、FET(Field Effect Transistor)またはMOSFETでもよい。 The inverter 41 is a circuit in which a switching element such as an IGBT (Insulated Gate Bipolar Transistor) has a three-phase bridge configuration or a two-phase bridge configuration. The switching element used for the inverter 41 is not limited to the IGBT, but may be a switching element made of a WBG semiconductor, an IGCT (Integrated Gate Commutated Thyristor), an FET (Field Effect Transistor) or a MOSFET.
 モータ電流検出部44は、インバータ41とモータ42との間に流れる電流を検出する。インバータ制御部43は、モータ電流検出部44で検出された電流を用いて、モータ42が所望の回転数にて回転するように、インバータ41内のスイッチング素子を駆動するためのPWM信号を生成してインバータ41へ印加する。インバータ制御部43は、制御部10と同様に、プロセッサ及びメモリにより実現される。なおモータ駆動装置101のインバータ制御部43と、電力変換装置100の制御部10は、1つの回路で実現してもよい。 (4) The motor current detector 44 detects a current flowing between the inverter 41 and the motor 42. The inverter control unit 43 uses the current detected by the motor current detection unit 44 to generate a PWM signal for driving a switching element in the inverter 41 so that the motor 42 rotates at a desired rotation speed. To the inverter 41. The inverter control unit 43 is realized by a processor and a memory, similarly to the control unit 10. Note that the inverter control unit 43 of the motor drive device 101 and the control unit 10 of the power conversion device 100 may be realized by one circuit.
 電力変換装置100がモータ駆動装置101に用いられる場合、ブリッジ回路3の制御に必要な母線電圧Vdcが、モータ42の運転状態に応じて変化する。一般に、モータ42の回転数が高回転になる程、インバータ41の出力電圧を高くする必要がある。このインバータ41の出力電圧の上限は、インバータ41への入力電圧、すなわち電力変換装置100の出力である母線電圧Vdcにより制限される。インバータ41からの出力電圧が、母線電圧Vdcにより制限される上限を超えて飽和する領域を過変調領域と呼ぶ。 When the power conversion device 100 is used for the motor drive device 101, the bus voltage Vdc necessary for controlling the bridge circuit 3 changes according to the operation state of the motor 42. Generally, it is necessary to increase the output voltage of the inverter 41 as the rotation speed of the motor 42 increases. The upper limit of the output voltage of inverter 41 is limited by the input voltage to inverter 41, that is, the bus voltage Vdc output from power conversion device 100. A region where the output voltage from the inverter 41 saturates beyond the upper limit limited by the bus voltage Vdc is called an overmodulation region.
 このようなモータ駆動装置101において、モータ42が低回転の範囲、すなわち過変調領域に到達しない範囲では、母線電圧Vdcを昇圧させる必要はない。一方、モータ42が高回転となった場合には、母線電圧Vdcを昇圧させることで、過変調領域をより高回転側にすることができる。これにより、モータ42の運転範囲を高回転側に拡大できる。 In such a motor drive device 101, it is not necessary to increase the bus voltage Vdc in a range where the motor 42 is in a low rotation range, that is, in a range where the motor 42 does not reach the overmodulation region. On the other hand, when the motor 42 rotates at a high speed, the overmodulation region can be shifted to a higher rotation side by increasing the bus voltage Vdc. Thereby, the operation range of the motor 42 can be expanded to the high rotation side.
 また、モータ42の運転範囲を拡大する必要がなければ、その分、モータ42が備える固定子への巻線の巻数を増やすことができる。巻線の巻数を増やすことにより、低回転の領域では、巻線の両端に発生するモータ電圧が高くなり、その分、巻線に流れる電流が低下するため、インバータ41内のスイッチング素子のスイッチング動作で生じる損失を低減できる。モータ42の運転範囲の拡大と、低回転の領域の損失改善との双方の効果を得る場合には、モータ42の巻線の巻数は適切な値に設定される。 If the operating range of the motor 42 does not need to be expanded, the number of windings on the stator of the motor 42 can be increased accordingly. By increasing the number of windings of the winding, the motor voltage generated at both ends of the winding increases in the low rotation region, and the current flowing through the winding decreases accordingly, so that the switching operation of the switching element in the inverter 41 is performed. Can be reduced. In order to obtain both effects of expanding the operation range of the motor 42 and improving the loss in the low rotation speed region, the number of windings of the motor 42 is set to an appropriate value.
 以上説明したように、本実施の形態によれば、電力変換装置100を用いることによりアーム間の発熱の偏りが低減され、信頼性が高く高出力のモータ駆動装置101を実現できる。 As described above, according to the present embodiment, the use of the power converter 100 reduces the bias of heat generation between the arms, and realizes a highly reliable and high-output motor drive device 101.
実施の形態4.
 実施の形態4では、実施の形態3で説明したモータ駆動装置101を備える空気調和機について説明する。
Embodiment 4 FIG.
In the fourth embodiment, an air conditioner including the motor drive device 101 described in the third embodiment will be described.
 図13は、実施の形態4に係る空気調和機700の構成例を示す図である。空気調和機700は、冷凍サイクル装置の一例であり、実施の形態3のモータ駆動装置101及びモータ42を備える。空気調和機700は、圧縮機構87及びモータ42を内蔵した圧縮機81と、四方弁82と、室外熱交換器83と、膨張弁84と、室内熱交換器85と、冷媒配管86とを備える。空気調和機700は、室外機が室内機から分離されたセパレート型空気調和機に限定されず、圧縮機81、室内熱交換器85及び室外熱交換器83が1つの筐体内に設けられた一体型空気調和機でもよい。モータ42は、モータ駆動装置101により駆動される。 FIG. 13 is a diagram illustrating a configuration example of an air conditioner 700 according to Embodiment 4. The air conditioner 700 is an example of a refrigeration cycle device, and includes the motor driving device 101 and the motor 42 according to the third embodiment. The air conditioner 700 includes a compressor 81 including a compression mechanism 87 and a motor 42, a four-way valve 82, an outdoor heat exchanger 83, an expansion valve 84, an indoor heat exchanger 85, and a refrigerant pipe 86. . The air conditioner 700 is not limited to a separate type air conditioner in which an outdoor unit is separated from an indoor unit, and includes a compressor 81, an indoor heat exchanger 85, and an outdoor heat exchanger 83 provided in one housing. A body type air conditioner may be used. The motor 42 is driven by the motor driving device 101.
 圧縮機81の内部には、冷媒を圧縮する圧縮機構87と、圧縮機構87を動作させるモータ42とが設けられる。圧縮機81、四方弁82、室外熱交換器83、膨張弁84、室内熱交換器85及び冷媒配管86に冷媒が循環することにより、冷凍サイクルが構成される。なお、空気調和機700が備える構成要素は、冷凍サイクルを備える冷蔵庫または冷凍庫といった機器にも適用可能である。 Inside the compressor 81, a compression mechanism 87 for compressing the refrigerant and a motor 42 for operating the compression mechanism 87 are provided. The refrigerant circulates through the compressor 81, the four-way valve 82, the outdoor heat exchanger 83, the expansion valve 84, the indoor heat exchanger 85, and the refrigerant pipe 86 to form a refrigeration cycle. Note that the components included in the air conditioner 700 can be applied to devices such as a refrigerator or a freezer including a refrigeration cycle.
 また、実施の形態4では、圧縮機81の駆動源にモータ42が利用され、モータ駆動装置101によりモータ42を駆動する構成例を説明した。しかしながら、空気調和機700が備える不図示の室内機送風機及び室外機送風機を駆動する駆動源にモータ42を適用し、当該モータ42をモータ駆動装置101で駆動してもよい。また、室内機送風機、室外機送風機及び圧縮機81の駆動源にモータ42を適用し、当該モータ42をモータ駆動装置101で駆動してもよい。 In the fourth embodiment, the configuration example in which the motor 42 is used as the driving source of the compressor 81 and the motor 42 is driven by the motor driving device 101 has been described. However, the motor 42 may be applied to a drive source for driving an indoor unit blower and an outdoor unit blower (not shown) included in the air conditioner 700, and the motor 42 may be driven by the motor driving device 101. Further, the motor 42 may be applied to a drive source of the indoor unit blower, the outdoor unit blower, and the compressor 81, and the motor 42 may be driven by the motor driving device 101.
 また、空気調和機700では、出力が定格出力の半分以下である中間条件、すなわち低出力条件での運転が年間を通じて支配的であるため、中間条件での年間の消費電力への寄与度が高くなる。また、空気調和機700では、モータ42の回転数が低く、モータ42の駆動に必要な母線電圧Vdcは低い傾向にある。このため、空気調和機700に用いられるスイッチング素子は、パッシブな状態で動作させることがシステム効率の面から有効である。従って、パッシブな状態から高周波スイッチング状態までの幅広い運転モードで損失の低減が可能な電力変換装置100は、空気調和機700にとって有用である。上述した通り、インタリーブ方式ではリアクタ2を小型化できるが、空気調和機700では、中間条件での運転が多いため、リアクタ2を小型化する必要がなく、電力変換装置100の構成及び動作の方が、高調波の抑制、電源力率の面で有効である。 Further, in the air conditioner 700, since the operation under the intermediate condition where the output is less than half of the rated output, that is, the operation under the low output condition is dominant throughout the year, the contribution to the annual power consumption under the intermediate condition is high. Become. In the air conditioner 700, the rotation speed of the motor 42 is low, and the bus voltage Vdc required for driving the motor 42 tends to be low. For this reason, it is effective in terms of system efficiency to operate the switching element used in the air conditioner 700 in a passive state. Therefore, power converter 100 capable of reducing loss in a wide range of operation modes from a passive state to a high-frequency switching state is useful for air conditioner 700. As described above, the reactor 2 can be downsized by the interleave method. However, in the air conditioner 700, there are many operations under intermediate conditions. Therefore, the reactor 2 does not need to be downsized. However, it is effective in terms of suppressing harmonics and power factor.
 また、電力変換装置100は、スイッチング損失を抑制できるため、電力変換装置100の温度上昇が抑制され、不図示の室外機送風機のサイズを小型化しても、電力変換装置100に搭載される基板の冷却能力を確保できる。従って、電力変換装置100は、高効率であると共に4.0kW以上の高出力の空気調和機700に好適である。 Further, since the power converter 100 can suppress the switching loss, the temperature rise of the power converter 100 is suppressed, and even if the size of the outdoor unit blower (not shown) is reduced, the size of the board mounted on the power converter 100 can be reduced. Cooling capacity can be secured. Therefore, the power converter 100 is suitable for an air conditioner 700 having high efficiency and high output of 4.0 kW or more.
 また、本実施の形態によれば、電力変換装置100を用いることによりアーム間の発熱の偏りが低減されるため、スイッチング素子の高周波駆動によるリアクタ2の小型化を実現でき、空気調和機700の重量の増加を抑制できる。また、本実施の形態によれば、スイッチング素子の高周波駆動により、スイッチング損失が低減され、エネルギー消費率が低く、高効率の空気調和機700を実現できる。 Further, according to the present embodiment, since the bias of heat generation between the arms is reduced by using power converter 100, downsizing of reactor 2 by high-frequency driving of the switching element can be realized, and air conditioner 700 An increase in weight can be suppressed. Further, according to the present embodiment, the high-frequency driving of the switching element can reduce the switching loss, realize a low energy consumption rate, and realize a highly efficient air conditioner 700.
 以上の実施の形態に示した構成は、本発明の内容の一例を示すものであり、別の公知の技術と組み合わせることも可能であるし、本発明の要旨を逸脱しない範囲で、構成の一部を省略、変更することも可能である。 The configurations described in the above embodiments are merely examples of the contents of the present invention, and can be combined with other known technologies, and can be combined with other known technologies without departing from the gist of the present invention. Parts can be omitted or changed.
 1 交流電源、2 リアクタ、3 ブリッジ回路、4 平滑コンデンサ、5 電源電圧検出部、6 電源電流検出部、7 母線電圧検出部、10 制御部、31 第1のアーム、32 第2のアーム、41 インバータ、42 モータ、43 インバータ制御部、44 モータ電流検出部、50 負荷、81 圧縮機、82 四方弁、83 室外熱交換器、84 膨張弁、85 室内熱交換器、86 冷媒配管、87 圧縮機構、100 電力変換装置、101 モータ駆動装置、201 プロセッサ、202 メモリ、311,312,321,322 スイッチング素子、311a,312a,321a,322a 寄生ダイオード、501 第1の配線、502 第2の配線、503 第3の配線、504 第4の配線、506 第1の接続点、508 第2の接続点、600 半導体基板、601,603 領域、602 酸化絶縁膜、604 チャネル、700 空気調和機。 1 AC power supply, 2 reactor, 3 bridge circuit, 4 smoothing capacitor, 5 power supply voltage detector, 6 power supply current detector, 7 bus voltage detector, 10 controller, 31 first arm, 32 second arm, 41 Inverter, 42 motor, 43 inverter control unit, 44 検 出 motor current detection unit, 50 load, 81 compressor, 82 four-way valve, 83 outdoor heat exchanger, 84 expansion valve, 85 indoor heat exchanger, 86 refrigerant pipe, 87 compression mechanism , 100 power converter, 101 motor drive, 201 processor, 202 memory, 311, 312, 321, 322 switching element, 311a, 312a, 321a, 322a parasitic diode, 501 first wiring, 502 second wiring, 503 Third wiring, 504 # fourth wiring, 506 # first Connection point, 508 a second connection point, 600 a semiconductor substrate, 601 and 603 regions, 602 oxide insulating film, 604 channels, 700 air conditioner.

Claims (11)

  1.  第一端部と第二端部を有し、前記第一端部が交流電源に接続されるリアクトルと、
     前記リアクトルの前記第二端部に接続され、少なくとも1つ以上のスイッチング素子を備え、交流電源から出力される交流電圧を直流電圧に変換するブリッジ回路と、
     前記交流電源の電流を検出する電流検出部と、
     前記電流検出部で検出された電流値に応じて前記スイッチング素子のオンオフを制御する制御部と、
     を備え、
     前記制御部は前記電流検出部で検出された過去の電流値を用いてオンオフ制御する電力変換装置。
    A reactor having a first end and a second end, wherein the first end is connected to an AC power supply;
    A bridge circuit that is connected to the second end of the reactor and includes at least one or more switching elements, and converts an AC voltage output from an AC power supply into a DC voltage;
    A current detection unit that detects a current of the AC power supply,
    A control unit that controls on / off of the switching element according to a current value detected by the current detection unit;
    With
    The power converter in which the control unit performs on / off control using a past current value detected by the current detection unit.
  2.  前記制御部は、前記電流検出部で過去に検出された電流値である第1の電流値と前記電流検出部で新たに検出した電流値である第2の電流値とを用いて前記スイッチング素子のオンオフを制御する請求項1に記載の電力変換装置。 The control unit uses the first current value, which is a current value detected in the past by the current detection unit, and a second current value, which is a current value newly detected by the current detection unit, to switch the switching element. The power converter according to claim 1, which controls on / off of the power converter.
  3.  前記制御部は、前記第1の電流値および前記第2の電流値より算出した予測値によって前記スイッチング素子のオンオフを制御する請求項2に記載の電力変換装置。 The power converter according to claim 2, wherein the control unit controls on / off of the switching element based on a predicted value calculated from the first current value and the second current value.
  4.  前記制御部は、前記電流値の極性が正の場合、前記電流値が増加中に前記予測値を算出する頻度より、前記電流値が減少中に前記予測値を算出する頻度を高くする、
     請求項3に記載の電力変換装置。
    When the polarity of the current value is positive, the control unit increases the frequency of calculating the predicted value while the current value is decreasing, higher than the frequency of calculating the predicted value while the current value is increasing.
    The power converter according to claim 3.
  5.  前記制御部は、前記電流値の極性が負の場合、前記電流値が減少中に前記予測値を算出する頻度より、前記電流値が増加中に前記予測値を算出する頻度を高くする、
     請求項3に記載の電力変換装置。
    The controller, when the polarity of the current value is negative, to increase the frequency of calculating the predicted value while the current value is increasing, than the frequency of calculating the predicted value while the current value is decreasing,
    The power converter according to claim 3.
  6.  前記制御部は、前記第2の電流値がゼロのときは前記予測値を算出しない、
     請求項3に記載の電力変換装置。
    The control unit does not calculate the predicted value when the second current value is zero,
    The power converter according to claim 3.
  7.  前記制御部は、前記予測値の絶対値が電流閾値以下の場合、前記電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子をオフにする、
     請求項3に記載の電力変換装置。
    When the absolute value of the predicted value is equal to or less than a current threshold, the control unit turns off a switching element that is on among switching elements that are controlled according to the polarity of the current.
    The power converter according to claim 3.
  8.  前記制御部は、前記予測値の絶対値が電流閾値以上の場合、前記電流値の絶対値が前記電流閾値になる時間を算出する、
     請求項3に記載の電力変換装置。
    When the absolute value of the predicted value is equal to or greater than the current threshold, the control unit calculates a time at which the absolute value of the current value becomes the current threshold.
    The power converter according to claim 3.
  9.  前記制御部は、推定された時間までに、前記電流の極性に応じて制御しているスイッチング素子のうちオンされているスイッチング素子をオフにする、
     請求項8に記載の電力変換装置。
    By the estimated time, the control unit turns off the switching elements that are turned on among the switching elements that are controlled according to the polarity of the current,
    The power converter according to claim 8.
  10.  モータを駆動するモータ駆動装置であって、
     請求項1から9の何れか一項に記載の電力変換装置と、
     前記電力変換装置から出力される直流電力を交流電力に変換して前記モータへ出力するインバータと、
     を備えるモータ駆動装置。
    A motor driving device for driving a motor,
    A power converter according to any one of claims 1 to 9,
    An inverter that converts DC power output from the power converter to AC power and outputs the AC power to the motor;
    A motor drive device comprising:
  11.  モータと、
     請求項10に記載のモータ駆動装置と、
     を備える空気調和機。
    Motor and
    A motor drive device according to claim 10,
    Air conditioner equipped with.
PCT/JP2018/036611 2018-09-28 2018-09-28 Power conversion apparatus, motor drive apparatus, and air conditioner WO2020066034A1 (en)

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US11764719B2 (en) 2019-08-30 2023-09-19 Mitsubishi Electric Corporation Direct current power supply device, motor drive apparatus, blower, compressor, and air conditioner
US11874020B2 (en) 2019-08-30 2024-01-16 Mitsubishi Electric Corporation Motor drive apparatus, blower, compressor, and air conditioner

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WO2018073875A1 (en) * 2016-10-17 2018-04-26 三菱電機株式会社 Power conversion device, motor drive device, and air conditioner

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JPH118975A (en) * 1997-06-13 1999-01-12 Toyo Electric Mfg Co Ltd Controller for converter
JP2011050221A (en) * 2009-08-28 2011-03-10 Seiko Instruments Inc Synchronous rectification type voltage converter
WO2018073875A1 (en) * 2016-10-17 2018-04-26 三菱電機株式会社 Power conversion device, motor drive device, and air conditioner

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US11764719B2 (en) 2019-08-30 2023-09-19 Mitsubishi Electric Corporation Direct current power supply device, motor drive apparatus, blower, compressor, and air conditioner
US11874020B2 (en) 2019-08-30 2024-01-16 Mitsubishi Electric Corporation Motor drive apparatus, blower, compressor, and air conditioner

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