WO2015125539A1 - Power transmission system - Google Patents
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- WO2015125539A1 WO2015125539A1 PCT/JP2015/051477 JP2015051477W WO2015125539A1 WO 2015125539 A1 WO2015125539 A1 WO 2015125539A1 JP 2015051477 W JP2015051477 W JP 2015051477W WO 2015125539 A1 WO2015125539 A1 WO 2015125539A1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/05—Circuit arrangements or systems for wireless supply or distribution of electric power using capacitive coupling
Definitions
- the present invention relates to a power transmission system that wirelessly transmits power from a power transmission device to a power reception device.
- Patent Document 1 discloses an electric field coupling type power transmission system, in which a power transmission drive frequency is set in order to increase power transmission efficiency from a power transmission device to a power reception device.
- a resonance circuit is provided in each of the power transmission device and the power reception device, and a frequency sweep is performed in a state where the power reception device is mounted on the power transmission device to search for a resonance frequency (peak value of the drive voltage).
- the drive frequency is set from the resonance frequency obtained by the search, and the power is transmitted to the power receiving apparatus.
- the resonance circuit includes a capacitance of the coupling portion of the power transmission device and the power reception device, and an inductor.
- the power receiving device of the power transmission system is required to be small and thin. Therefore, it is conceivable to use a piezoelectric device (piezoelectric resonator, piezoelectric transformer) for the inductor.
- Patent Document 2 discloses a power transmission system using a piezoelectric transformer for stepping down a power receiving device.
- the first resonance circuit and the second resonance circuit are configured in the power receiving device, and a high frequency high voltage frequency generated by the power transmission device is combined with the two resonance circuits. It is set between two resonance frequencies due to resonance.
- the ratio between the power receiving device side voltage and the power transmitting device side voltage when load variation or drive frequency variation of the power receiving device occurs can be stabilized.
- JP 2012-70614 A International Publication 2012/172929 Pamphlet
- an object of the present invention is to provide a power transmission system that performs power transmission while avoiding a decrease in transmission efficiency.
- power is transmitted from the power transmitting device to the power receiving device by electric field coupling between the power transmitting side first electrode and the power transmitting side second electrode of the power transmitting device and the power receiving side first electrode and the power receiving side second electrode of the power receiving device.
- the power transmission device includes an inverter circuit that converts a DC voltage output from a DC power source into an AC voltage, a PWM control circuit that PWM-controls the inverter circuit at a set drive frequency, and the inverter A step-up transformer that boosts an alternating voltage output from the circuit and applies the boosted voltage to the power transmission side first electrode and the power transmission side second electrode; the step-up transformer; the power transmission side first electrode; and the power transmission side second electrode; A first resonance circuit connected between the step-up transformer and a part of the step-up transformer, and the power reception device includes the power reception side first electrode and the power reception side second power.
- a piezoelectric transformer for stepping down a voltage induced by the second transformer circuit and a second resonant circuit configured to include a part of an equivalent circuit of the piezoelectric transformer and having the same resonant frequency as the first resonant circuit,
- the power transmission device sweeps the drive frequency and detects a resonance frequency of the first resonance circuit and the second resonance circuit, and a resonance detected by the resonance frequency detection unit at a predetermined period.
- a drive frequency setting unit that sets the frequency to the drive frequency.
- the drive frequency is set at a predetermined cycle. By doing so, it is possible to avoid a decrease in transmission efficiency.
- the drive frequency setting unit preferably lengthens the predetermined period as the amount of change in the resonance frequency detected by the resonance frequency detection unit at different timings decreases.
- the power transmission device includes a current detection unit that detects a current flowing through the inverter circuit, and the resonance frequency detection unit has a frequency characteristic of a current value detected by the current detection unit when the drive frequency is swept. It is preferable to detect the resonance frequency based on the above.
- the resonance frequency is detected by detecting the current flowing through the inverter circuit of the power transmission device, the resonance frequency can be detected without monitoring the state of the piezoelectric transformer on the power reception device side.
- the power transmission device stores a transmission power detection unit that detects transmission power to be transmitted to the power receiving device, and a memory that stores detection conditions for the resonance frequencies of the first resonance circuit and the second resonance circuit according to transmission power
- the resonance frequency detection unit acquires a detection condition according to the transmission power detected by the transmission power detection unit from the storage unit, and when the acquired detection condition and the drive frequency are swept It is preferable to detect the resonance frequency based on the frequency characteristic of the current value detected by the current detection unit.
- the resonance frequency detection condition corresponding to the transmission power is stored in advance as in the above configuration. Even if the power changes, an appropriate resonance frequency can be easily detected.
- Circuit diagram of power transmission system according to Embodiment 1 The figure which shows the equivalent circuit of FIG. Functional block diagram of control circuit
- the figure which shows the frequency characteristic of the transmission current IDC Perspective view of piezoelectric transformer Sectional view taken along line VI-VI in FIG. Sectional view taken along line VII-VII in FIG.
- the flowchart which shows the process which a control part performs Flow chart showing drive frequency setting process Circuit diagram of power transmission system according to Embodiment 2
- FIG. 1 is a circuit diagram of a power transmission system according to the first embodiment.
- FIG. 2 is a diagram showing an equivalent circuit of FIG.
- the power transmission system 1 includes a power transmission device 101 and a power reception device 201.
- the power receiving apparatus 201 includes a load circuit RL.
- the load circuit RL includes a charging circuit and a secondary battery.
- the power receiving apparatus 201 is a portable electronic device provided with the secondary battery, for example. Examples of portable electronic devices include cellular phones, PDAs (Personal Digital Assistants), portable music players, notebook PCs, and digital cameras.
- the power transmission device 101 is a charging stand for charging the secondary battery of the power receiving device 201 placed thereon.
- the power transmission apparatus 101 includes a DC power supply 11 that outputs a DC voltage Vin.
- the DC power source 11 is an AC adapter connected to a commercial power source.
- the inverter circuit 12 is connected to the DC power source 11.
- the inverter circuit 12 includes MOS-FET switching elements Q1, Q2, Q3, and Q4.
- switch elements Q1 and Q2 are connected in series, and switch elements Q3 and Q4 are connected in series. Further, the connection point of the switch elements Q1, Q2 and the connection point of the switch elements Q3, Q4 are connected to the primary coil of the step-up transformer T1.
- the switching elements Q1, Q2, Q3, and Q4 of the inverter circuit 12 are PWM-controlled by the PWM control circuit 15.
- the PWM control circuit 15 is not shown.
- the PWM control circuit 15 turns on and off the switch elements Q1 and Q4 and the switch elements Q2 and Q3 alternately. Thereby, the inverter circuit 12 converts the DC voltage Vin into an AC voltage.
- the PWM control circuit 15 includes an error amplifier that amplifies the error voltage between the feedback voltage that varies according to the output voltage and the reference voltage and outputs an error voltage signal. Then, a PWM signal having a duty corresponding to the comparison result between the error voltage signal and the triangular wave is generated. The PWM control circuit 15 outputs the generated PWM signal to the gates of the switch elements Q1, Q2, Q3, and Q4.
- the power transmission device 101 includes a control circuit 16.
- the control circuit 16 causes the PWM control circuit 15 to generate a PWM signal having a predetermined duty ratio.
- the control circuit 16 will be described in detail later.
- the step-up transformer T1 has a secondary coil connected to the active electrode 13 and the passive electrode 14.
- the step-up transformer T1 steps up the AC voltage converted by the inverter circuit 12 and applies it to the active electrode 13 and the passive electrode 14.
- the active electrode 13 is an example of the “power transmission side first electrode” according to the present invention
- the passive electrode 14 is an example of the “power transmission side second electrode” according to the present invention.
- Capacitors C21 and C22 are connected in series to the active electrode 13 and the passive electrode 14.
- the voltage V1 applied to the active electrode 13 and the passive electrode 14 is capacitively divided by the capacitors C21 and C22.
- the control circuit 16 rectifies the AC voltage divided in capacity and detects the voltage V1.
- a resistor R1 for current detection is connected to the passive electrode 14.
- the control circuit 16 detects a current I1 flowing through the resistor R1.
- the control circuit 16 acquires the power transmitted from the power transmission device 101 to the power reception device 201 from the current I1 and the voltage V1.
- the capacitor C1 is connected in parallel to the secondary coil of the step-up transformer T1, and the capacitor C1 forms a parallel resonance circuit 17 (see FIG. 2) together with the secondary coil of the step-up transformer T1.
- the power receiving apparatus 201 includes an active electrode 23 and a passive electrode 24.
- the active electrode 23 and the passive electrode 24 face the active electrode 13 and the passive electrode 14 of the power transmission device 101 with a gap when the power receiving device 201 is placed on the power transmission device 101.
- a voltage is applied between the active electrode 13 and the passive electrode 14, the active electrodes 13 and 23 that are arranged to face each other are subjected to electric field coupling, and the electrode of the power transmission device 101 and the electrode of the power reception device 201 are not connected via this coupling. Power is transmitted from the power transmitting apparatus 101 to the power receiving apparatus 201 in a contact state.
- the active electrode 23 is an example of a “power receiving side first electrode” according to the present invention
- the passive electrode 24 is an example of a “power receiving side second electrode” according to the present invention.
- the piezoelectric transformer 22 is connected to the active electrode 23 and the passive electrode 24 of the power receiving apparatus 201.
- the piezoelectric transformer 22 has a pair of first input electrodes E11 and E12 and a pair of second input electrodes E21 and E22.
- the first input electrodes E11 and E12 are connected to the active electrode 23.
- the second input electrodes E21 and E22 are connected to the passive electrode 24.
- the piezoelectric transformer 22 includes a pair of first output electrodes E31 and E32, a pair of second output electrodes E41 and E42, and a pair of third output electrodes E51 and E52.
- the first output electrodes E31 and E32, the second output electrodes E41 and E42, and the third output electrodes E51 and E52 are connected to the rectifying and smoothing circuit 25.
- the piezoelectric transformer 22 steps down the voltage input from the first input electrodes E11 and E12 and the second input electrodes E21 and E22, and the first output electrodes E31 and E32, the second output electrodes E41 and E42, and the third output electrode. Output from E51 and E52 to the rectifying and smoothing circuit 25.
- the piezoelectric transformer 22 is represented by a transformer T2, capacitors C21 and C22, a capacitor Cp, an inductor Lp, a resistor Rp, and the like.
- the capacitor C21 is an equivalent input capacity of the piezoelectric transformer 22
- the capacitor C22 is an equivalent output capacity of the piezoelectric transformer 22.
- the capacitor Cp and the inductor Lp are electromechanical parameters.
- the resonance frequency of the piezoelectric transformer 22 is determined mainly by the resonance of the series resonance circuit 221 by the capacitor Cp and the inductor Lp. Since electrical energy conversion is via elastic vibration, it has a natural resonance frequency determined by the elastic wave propagation velocity and dimensions of the piezoelectric ceramic.
- the piezoelectric transformer 22 is designed such that the series resonance circuit 221 has the same resonance frequency as the parallel resonance circuit 17 formed on the power transmission device 101 side.
- An inductor L 2 is connected to the output side of the piezoelectric transformer 22, and this inductor L 2 constitutes a parallel resonance circuit 222 with a capacitor C 22 that is an equivalent output capacity of the piezoelectric transformer 22.
- the inductor L2 has a circuit constant set so that the parallel resonant circuit 222 has the same resonance frequency as the parallel resonant circuit 17 and the series resonant circuit 221.
- the piezoelectric transformer 22 will self-heat, and temperature will rise with progress of time. This heat generation affects the constants of each element equivalently expressed such as the capacitor Cp of the piezoelectric transformer 22.
- the series resonance circuit 221 and the parallel resonance circuit 222 are configured so as to have the same resonance frequency as that of the parallel resonance circuit 17 in a state where the piezoelectric transformer 22 is not generating heat (that is, in a state where the piezoelectric transformer 22 is cooled). A constant is set.
- the voltage stepped down by the piezoelectric transformer 22 is output to the rectifying / smoothing circuit 25.
- the rectifying / smoothing circuit 25 includes a smoothing circuit including a capacitor and an inductor, a diode bridge, and a DC-DC converter that converts the voltage into a predetermined value and outputs the voltage.
- the rectifying / smoothing circuit 25 rectifies and smoothes the AC voltage and outputs it to the load circuit RL.
- the output voltage output from the rectifying / smoothing circuit 25 to the load circuit RL is represented by Vout.
- FIG. 3 is a functional block diagram of the control circuit 16.
- the control circuit 16 includes a microcomputer and has functions such as an IDC detection unit 161, a transmission power acquisition unit 162, a frequency control unit 163, a storage unit 164, and a control unit 165.
- the IDC detection unit 161 detects the transmission current IDC. Specifically, a resistance R2 for current detection is connected between the DC power supply 11 and the inverter circuit 12, and the IDC detection unit 161 detects the transmission current IDC flowing through the inverter circuit 12 by the voltage drop of the resistance R2. .
- the IDC detection unit 161 corresponds to a “current detection unit” according to the present invention.
- the transmission power acquisition unit 162 acquires the voltage V1 applied to the active electrode 13 and the passive electrode 14, and the current I1 flowing through the active electrode 13 and the passive electrode 14, and from the voltage V1 and the current I1, from the power transmission device 101.
- the transmission power to the power receiving apparatus 201 is acquired.
- the transmission power acquisition unit 162 is an example of the “transmission power detection unit” according to the present invention.
- the transmission power from the power transmission apparatus 101 to the power reception apparatus 201 may be obtained from the transmission current IDC detected by the IDC detection unit 161 and the input voltage Vin.
- the frequency control unit 163 outputs the duty ratio to the PWM control circuit 15 so that the inverter circuit 12 is PWM-controlled at a predetermined drive frequency.
- the PWM control circuit 15 controls the inverter circuit 12 with the input duty ratio. Further, the frequency control unit 163 sweeps (sweeps) the frequency at which the PWM control circuit 15 controls driving of the inverter circuit 12. For example, when the PWM control circuit 15 performs PWM control of the inverter circuit 12 at a frequency of 470 kHz, the frequency ranges of 468, 469, 470, 471, 472 kHz and 470 ⁇ 2 kHz are swept in increments of 1 kHz.
- the storage unit 164 stores setting conditions (detection conditions) for setting the drive frequency. Specifically, the storage unit 164 stores a plurality of setting conditions according to the transmission power from the power transmission apparatus 101 to the power reception apparatus 201. This setting condition is used when the control unit 165 sets the drive frequency from the frequency characteristic of the transmission current IDC.
- the control unit 165 controls the operations of the IDC detection unit 161, the transmission power acquisition unit 162, and the frequency control unit 163.
- the control unit 165 sets the drive frequency based on the power transmission current IDC detected by the IDC detection unit 161 when the frequency control unit 163 performs frequency sweep, that is, based on the frequency characteristics of the power transmission current IDC.
- FIG. 4 is a diagram illustrating frequency characteristics of the transmission current IDC.
- the horizontal axis in FIG. 4 is the frequency, and the vertical axis is the transmission current IDC, and shows characteristics when the load of the load circuit RL is changed.
- the characteristic curve of the frequency characteristic varies depending on the size of the load.
- the control unit 165 acquires the setting condition corresponding to the transmission power acquired by the transmission power acquisition unit 162 from the storage unit 164, and sets the drive frequency from the setting condition and the frequency characteristic of the transmission current IDC. Then, the frequency control unit 163 outputs a duty ratio to the PWM control circuit 15 so that the PWM control circuit 15 performs PWM control of the inverter circuit 12 at the drive frequency.
- the control unit 165 is an example of a “resonance frequency detection unit” and a “drive frequency setting unit” according to the present invention.
- FIG. 5 is a perspective view of the piezoelectric transformer 22. 6 is a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a sectional view taken along line VII-VII in FIG.
- the piezoelectric transformer 22 includes a rectangular plate-shaped piezoelectric plate 30.
- the piezoelectric plate 30 is formed by stacking, for example, PZT ceramic sheets.
- the length direction of the piezoelectric transformer 22 is the X-axis direction
- the width direction is the Y-axis direction
- the thickness direction is the Z-axis direction.
- the piezoelectric transformer 22 vibrates in the length direction in the (7 ⁇ / 2) resonance mode.
- ⁇ is one wavelength of vibration in the length direction. Therefore, the length of the piezoelectric transformer 22 in the X-axis direction is set to (7 ⁇ / 2).
- the width in the Y-axis direction and the thickness in the Z-axis direction are preferably less than ( ⁇ / 2). By doing so, the vibration in the width direction and the thickness direction is not coupled to the vibration in the length direction, and the vibration of the entire piezoelectric transformer 22 is not unstable.
- the piezoelectric plate 30 includes a first low voltage region 31, a first high voltage region 32, a second high voltage region 33, a second low voltage region 34, a third high voltage region 35, a fourth, along the X-axis direction.
- a high voltage region 36 and a third low voltage region 37 are formed.
- the lengths in the X-axis direction of the regions 31 to 37 are all ⁇ / 2.
- the first low voltage region 31, the second low voltage region 34, and the third low voltage region 37 are polarized in the Z-axis direction (thickness direction).
- the first low voltage region 31 and the third low voltage region 37 are polarized in the same direction, and the second low voltage region 34 is polarized in the opposite direction to the first low voltage region 31 and the third low voltage region 37.
- Examples of the polarization treatment method include a method of applying a voltage of 2 kV / mm to the piezoelectric plate in insulating oil at 170 ° C.
- first low voltage region 31 a pair of first output electrodes E31 and E32 are provided on the side surface of the piezoelectric plate 30 so as to face each other in the Y-axis direction.
- the first low voltage region 31 is provided with a plurality of internal electrodes E33 stacked in the Z-axis direction. As shown in FIG. 6, the internal electrodes E33 are alternately connected to the first output electrodes E31 and E32.
- the pair of second output electrodes E41 and E42 and the third output electrodes E51 and E52 are arranged so as to face each other in the Y-axis direction. It is provided on the side surface of the plate 30.
- the second low voltage region 34 and the third low voltage region 37 are provided with a plurality of internal electrodes E43 and E53 stacked in the Z-axis direction.
- the internal electrodes E43 are alternately connected to the second output electrodes E41 and E42, and the internal electrodes E53 are alternately connected to the third output electrodes E51 and E52.
- the first high voltage region 32, the second high voltage region 33, the third high voltage region 35, and the fourth high voltage region 36 are polarized in the X-axis direction.
- a pair of second input electrodes E21 and E22 are provided on the side surface of the piezoelectric plate 30 so as to face each other in the Y-axis direction.
- the first high voltage region 32 is provided with a plurality of internal electrodes E23 stacked in the Z-axis direction.
- the internal electrode E23 is connected to each of the second input electrodes E21 and E22.
- a pair of first input electrodes E11 and E12 are provided on the side surface of the piezoelectric plate 30 so as to face each other in the Y-axis direction.
- the fourth high voltage region 36 is provided with a plurality of internal electrodes E13 stacked in the Z-axis direction.
- the internal electrode E13 is connected to each of the first input electrodes E11 and E12.
- the first input electrodes E11 and E12 are connected to the active electrode 23, and the second input electrodes E21 and E22 are connected to the passive electrode 24.
- the first input electrodes E11 and E12 and the second input electrodes E21 and E22 cause the piezoelectric plate 30 to move in the X-axis direction.
- a voltage is applied in the length direction. Therefore, an electric field is applied to the first high voltage region 32, the second high voltage region 33, the third high voltage region 35, and the fourth high voltage region 36 in the polarization direction. Then, longitudinal vibration is excited in the direction orthogonal to the polarization direction by the inverse piezoelectric effect, that is, in the X-axis direction of the piezoelectric plate 30.
- the circuit constants are set so that the parallel resonant circuit 17, the series resonant circuit 221, and the parallel resonant circuit 222 have the same resonant frequency.
- the resonance frequency is 470 kHz.
- the drive frequency is determined by the resonance frequency.
- the parallel resonance circuit 17 and the parallel resonance circuit 222 have high impedance (maximum), and the series resonance circuit 221 has low impedance (minimum). For this reason, the voltage drop in the parallel resonant circuit 17, the series resonant circuit 221 and the parallel resonant circuit 222, that is, the voltage drop between the inverter circuit 12 and the load circuit RL is small.
- FIG. 8 is a diagram illustrating a frequency characteristic of a ratio (voltage conversion ratio) of the output voltage Vout of the power receiving device 201 with respect to the output voltage of the power transmitting device 101.
- the output voltage of the power transmission device 101 is a voltage V1 that is capacity-divided by the capacitors C21 and C22 and applied to the active electrode 13 and the passive electrode 14.
- the horizontal axis in FIG. 8 is the frequency, and the vertical axis is the transformation ratio (Vout / V1), which shows the characteristics when the load of the load circuit RL is changed.
- the circuit constant is set so that the resonance frequency of the parallel resonance circuit 17, the series resonance circuit 221 and the parallel resonance circuit 222 is about 470 kHz, and the resonance frequency is set as the drive frequency, so that the voltage is not related to the load fluctuation. Variation can be reduced. That is, efficient power transmission is possible regardless of load fluctuations.
- the resonance condition is deviated. For this reason, with the passage of time, the resonance frequency deviates from the drive frequency, and the transmission efficiency decreases. Therefore, in this embodiment, the resonance frequency is periodically detected and the drive frequency is corrected as needed.
- FIG. 9 is a flowchart showing processing executed by the control unit 165. The process illustrated in FIG. 9 is started, for example, when the power receiving apparatus 201 is placed on the power transmitting apparatus 101.
- the control unit 165 executes the drive frequency setting process shown in FIG. 10 (S1).
- FIG. 10 is a flowchart showing the drive frequency setting process.
- the frequency control unit 163 performs PWM control on the switch elements Q1 to Q4 of the inverter circuit 12 and sweeps the frequency of the output voltage of the inverter circuit 12 (S11). For example, when the current frequency is 470 kHz, sweeping is performed in increments of 1 kHz from 468 kHz to 472 kHz, 468, 469, 470, 471, 472 kHz.
- the IDC detection unit 161 detects the transmission current IDC, and the control unit 165 acquires the frequency characteristics of the transmission current IDC (S12).
- the control unit 165 acquires transmission power from the power transmission apparatus 101 to the power reception apparatus 201 from the voltage V1 applied to the active electrode 13 and the passive electrode 14 and the current I1 flowing through the active electrode 13 and the passive electrode 14 (S13). ).
- the control unit 165 acquires a setting condition opposite to the transmission power from the storage unit 164 (S14).
- the control unit 165 sets the drive frequency from the frequency characteristic acquired in S12 and the setting condition acquired in S14 (S15).
- the characteristic curve of the frequency characteristic of the transmission current IDC varies depending on the transmission power. For this reason, the resonance frequency is detected according to the setting condition corresponding to the transmission power, and the detected resonance frequency is set as the drive frequency.
- the frequency characteristic shown in FIG. 4 when the frequency characteristic obtained by the detection is the characteristic curve RC1, and the acquired setting condition is a condition that the maximum value of the obtained frequency is set as the drive frequency, FIG.
- the maximum value of the characteristic curve RC1 shown in FIG. 4 that is, the frequency of 470 kHz is set as the drive frequency.
- the frequency characteristic obtained by detection is the characteristic curve RC2
- the acquired setting condition is a condition that the minimum value of the obtained frequency is set as the drive frequency
- control unit 165 determines whether or not to end the process (S2).
- the case where the process is terminated is, for example, a case where the power receiving apparatus 201 is removed from the power transmitting apparatus 101.
- S2 YES
- this process ends.
- the control unit 165 determines whether or not the time T has elapsed since the drive frequency was set (S3). This time T can be appropriately changed, for example, 10 s.
- the control unit 165 executes the process of S2.
- the control unit 165 executes a drive frequency setting process (S4).
- This drive frequency setting process is the process shown in FIG.
- the drive frequency is set every time T.
- the piezoelectric transformer 22 When the power transmission is continuously performed, the piezoelectric transformer 22 self-heats with time, and the resonance frequency fluctuates due to the influence. For this reason, if power is always transmitted at the same drive frequency even after time has passed, the efficiency decreases. Therefore, the drive frequency is reset (corrected) every time T. Thereby, even if the resonance frequency of the piezoelectric transformer 22 is deviated, the drive frequency is reset according to the deviation, so that power can be transmitted efficiently.
- the control unit 165 determines whether or not the difference between the driving frequencies before and after the resetting is greater than or equal to a threshold value (for example, 50 mV) (S5). If it is equal to or greater than the threshold (S5: YES), the control unit 165 executes the process of S2. When it is not more than a threshold value (S5: NO), the control part 165 sets T to T1 (T1> t) (S6).
- a threshold value for example, 50 mV
- the transmission efficiency is reduced due to self-heating of the piezoelectric transformer 22, the transmission efficiency is reduced by periodically detecting the resonance frequency and resetting the drive frequency. Can be suppressed. Further, although the resonance frequency shifts with self-heating of the piezoelectric transformer 22, in this embodiment, since the resonance frequency is detected from the transmission current IDC by the power transmission apparatus 101, it is not necessary to monitor the piezoelectric transformer 22 on the power reception apparatus 201 side. .
- the resonance frequency may be detected by obtaining an inclination from the transmission current IDC detected by the IDC detection unit 161 when frequency sweeping is performed, and detecting inversion of the inclination.
- the resonance frequency may be detected from the amount of displacement of the transmission current IDC when the frequency is swept.
- the circuit constants are set in a state where the piezoelectric transformer 22 is not generating heat (that is, in a state where the piezoelectric transformer 22 is cooled), but in a state where the piezoelectric transformer 22 is generating heat (temperature of the piezoelectric transformer 22).
- the circuit constant may be set in a state where the Even in this case, a decrease in transmission efficiency can be suppressed by periodically detecting the resonance frequency and setting the drive frequency.
- FIG. 11 is a circuit diagram of a power transmission system according to the second embodiment.
- the power transmission system 2 according to the present embodiment includes a power transmission device 102 and a power reception device 201.
- the power receiving apparatus 201 is the same as that in the first embodiment.
- the power transmission device 102 includes a DC power supply 11, an inverter circuit 12, a step-up transformer T1, an active electrode 13, and a passive electrode 14 as with the power transmission device 101 according to the first embodiment.
- a capacitor C3 is connected to the secondary coil of the step-up transformer T1.
- the capacitor C3 forms a series resonance circuit 18 together with the leakage inductance (or the actual inductor) L1 of the step-up transformer T1.
- the series resonance circuit 18 has a circuit constant set so that the resonance frequency thereof becomes the resonance frequency of the resonance circuits 221 and 222 (see FIG. 2) of the power receiving apparatus 201. That is, in the first embodiment, the parallel resonance circuit 17 is formed in the power transmission device 101, whereas in this embodiment, the series resonance circuit 18 is formed in the power transmission device 102, which is different from the first embodiment. .
- the parallel resonance circuit 222 is set at the resonance frequency. Becomes high impedance (maximum), and the series resonance circuit 18 and the series resonance circuit 221 become low impedance (minimum). For this reason, the voltage drop in the series resonant circuit 18, the series resonant circuit 221 and the parallel resonant circuit 222, that is, the voltage drop between the inverter circuit 12 and the load circuit RL is small.
- FIG. 12 is a diagram showing the frequency characteristics of the transmission current IDC.
- the horizontal axis in FIG. 4 is the frequency
- the vertical axis is the transmission current IDC, and shows characteristics when the load of the load circuit RL is changed.
- the resonance frequency is detected according to the setting condition corresponding to the transmission power, and the detected resonance frequency is set as the drive frequency.
- the frequency characteristic obtained by detection is the characteristic curve RC3 shown in the figure, and the obtained setting condition is a condition that the minimum value of the obtained frequency is set as the drive frequency.
- the minimum value of the characteristic curve RC3 shown in FIG. 12 that is, the frequency of 470 kHz is set as the drive frequency.
- the frequency characteristic obtained by detection is the characteristic curve RC4 shown in the figure, and the obtained setting condition is a condition that the maximum value of the obtained frequency is set as the drive frequency.
- the minimum value of the characteristic curve RC4 shown in FIG. 12 that is, the frequency 470 kHz is set as the drive frequency.
- the drive frequency can be set to a frequency of 470 kHz.
- the resonance frequency is about 470 kHz
- the voltage conversion ratio of the output voltage of the power receiving apparatus 201 to the output voltage of the power transmission apparatus 102 at the resonance frequency is The transformation ratio is almost the same regardless of the load. That is, efficient power transmission is possible regardless of load fluctuations.
- Power transmission system 11 DC power supply 12 ... Inverter circuits 13 and 23 ... Active electrodes 14 and 24 ... Passive electrodes 15 ... PWM control circuit 16 ... Control circuit 17 ... Parallel resonant circuit 18 ... Series resonant circuit 22 ... Piezoelectric transformer 25 ... Rectification flat Circuit 30 ... piezoelectric plate 31 ... first low voltage region 32 ... first high voltage region 33 ... second high voltage region 34 ... second low voltage region 35 ... third high voltage region 36 ... fourth high voltage region 37 ... Third low voltage region 101, 102 ... Power transmission device 161 ... IDC detection unit 162 ... Transmission power acquisition unit 163 ... Frequency control unit 164 ... Storage unit 165 ... Control unit 201 ... Power reception device 221 ... Series resonance circuit 222 ... Parallel resonance circuit
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Abstract
A power transmission system (1) transmits power from a power transmission device (101) to a power reception device (201) by electric coupling. In the power transmission system (1), the power transmission device (101) comprises: a step-up transformer (T1) for stepping up the AC voltage output from an inverter circuit (12) and applying to an active electrode (13) and a passive electrode (14); and a parallel resonant circuit configured by including part of the step-up transformer. The power reception device (201) comprises: a piezoelectric transformer (22) for stepping down the voltage induced on an active electrode (23) and a passive electrode (24); and a series resonant circuit including the piezoelectric transformer (22) and having the same resonant frequency as the parallel resonant circuit. The power transmission device (101) sweeps driving frequency to detect the resonant frequency of the parallel resonant circuit and the series resonant circuit and sets the detected resonant frequency as the driving frequency at a predetermined cycle to PWM control the inverter circuit (12). This provides a power transmission system for transmitting power while avoiding the reduction of transmission efficiency.
Description
本発明は、送電装置から受電装置へ電力をワイヤレスで伝送する電力伝送システムに関する。
The present invention relates to a power transmission system that wirelessly transmits power from a power transmission device to a power reception device.
電力伝送システムとして、送電装置の電極と受電装置の電極とが電界結合して電力が伝送される電界結合方式のシステムがある。特許文献1には、電界結合方式の電力伝送システムであって、送電装置から受電装置への電力伝送効率を高めるために、電力伝送の駆動周波数を設定する方法が開示されている。特許文献1に記載の電力伝送システムは、送電装置及び受電装置それぞれに共振回路を設け、送電装置に受電装置を載置した状態で周波数スイープして共振周波数(駆動電圧のピーク値)を探索し、探索して得られた共振周波数から駆動周波数を設定し、受電装置への電力伝送を行う。
As a power transmission system, there is an electric field coupling system in which power is transmitted by electric field coupling between an electrode of a power transmission device and an electrode of a power reception device. Patent Document 1 discloses an electric field coupling type power transmission system, in which a power transmission drive frequency is set in order to increase power transmission efficiency from a power transmission device to a power reception device. In the power transmission system described in Patent Document 1, a resonance circuit is provided in each of the power transmission device and the power reception device, and a frequency sweep is performed in a state where the power reception device is mounted on the power transmission device to search for a resonance frequency (peak value of the drive voltage). The drive frequency is set from the resonance frequency obtained by the search, and the power is transmitted to the power receiving apparatus.
特許文献1に記載の電力伝送システムにおいて、共振回路は、送電装置及び受電装置の結合部の静電容量とインダクタとで構成される。そして、電力伝送システムの受電装置は、小型化、薄型化が要求されている。そこで、インダクタに、圧電デバイス(圧電共振子、圧電トランス)を用いることが考えられる。
In the power transmission system described in Patent Document 1, the resonance circuit includes a capacitance of the coupling portion of the power transmission device and the power reception device, and an inductor. The power receiving device of the power transmission system is required to be small and thin. Therefore, it is conceivable to use a piezoelectric device (piezoelectric resonator, piezoelectric transformer) for the inductor.
特許文献2には、受電装置での降圧に圧電トランスを用いた電力伝送システムが開示されている。特許文献2に係る電力伝送システムでは、受電装置に第1の共振回路、及び第2の共振回路を構成し、送電装置で発生させる高周波高電圧の周波数を、これら二つの共振回路が結合する複合共振による二つの共振周波数の間に設定している。これにより、受電装置の負荷変動又は駆動周波数変動が生じる場合の受電装置側電圧と送電装置側電圧との比を安定化できるようにしている。
Patent Document 2 discloses a power transmission system using a piezoelectric transformer for stepping down a power receiving device. In the power transmission system according to Patent Document 2, the first resonance circuit and the second resonance circuit are configured in the power receiving device, and a high frequency high voltage frequency generated by the power transmission device is combined with the two resonance circuits. It is set between two resonance frequencies due to resonance. Thus, the ratio between the power receiving device side voltage and the power transmitting device side voltage when load variation or drive frequency variation of the power receiving device occurs can be stabilized.
しかしながら、特許文献2のように圧電トランスを用いた場合、電力伝送時の温度変化により圧電トランスの特性が変化し、これにより、共振条件がずれるおそれがある。共振条件がずれると、ずれる前の共振条件で設定した駆動周波数で電力伝送を行っても、高い伝送効率が得られないといった問題がある。
However, when a piezoelectric transformer is used as in Patent Document 2, the characteristics of the piezoelectric transformer change due to a temperature change during power transmission, which may cause the resonance condition to shift. If the resonance condition is deviated, there is a problem that high transmission efficiency cannot be obtained even if power transmission is performed at the drive frequency set in the resonance condition before the deviation.
そこで、本発明の目的は、伝送効率の低下を回避して電力伝送を行う電力伝送システムを提供することにある。
Therefore, an object of the present invention is to provide a power transmission system that performs power transmission while avoiding a decrease in transmission efficiency.
本発明は、送電装置の送電側第1電極及び送電側第2電極と、受電装置の受電側第1電極及び受電側第2電極とが、電界結合することで送電装置から受電装置へ電力を伝送する電力伝送システムにおいて、前記送電装置は、直流電源から出力された直流電圧を交流電圧に変換するインバータ回路と、設定された駆動周波数で前記インバータ回路をPWM制御するPWM制御回路と、前記インバータ回路から出力される交流電圧を昇圧し、前記送電側第1電極及び前記送電側第2電極へ印加する昇圧トランスと、前記昇圧トランスと、前記送電側第1電極及び前記送電側第2電極との間に接続された、又は、前記昇圧トランスの一部と共に構成される、第1の共振回路と、を備え、前記受電装置は、前記受電側第1電極及び前記受電側第2電極に誘起される電圧を降圧する圧電トランスと、前記圧電トランスの等価回路の一部を含んで構成され、前記第1の共振回路と同じ共振周波数を有する第2の共振回路と、を備え、前記送電装置は、前記駆動周波数を掃引すると共に、前記第1の共振回路及び前記第2の共振回路の共振周波数を検出する共振周波数検出部と、所定周期で、前記共振周波数検出部が検出した共振周波数を前記駆動周波数に設定する駆動周波数設定部と、を備えたことを特徴とする。
According to the present invention, power is transmitted from the power transmitting device to the power receiving device by electric field coupling between the power transmitting side first electrode and the power transmitting side second electrode of the power transmitting device and the power receiving side first electrode and the power receiving side second electrode of the power receiving device. In the power transmission system for transmission, the power transmission device includes an inverter circuit that converts a DC voltage output from a DC power source into an AC voltage, a PWM control circuit that PWM-controls the inverter circuit at a set drive frequency, and the inverter A step-up transformer that boosts an alternating voltage output from the circuit and applies the boosted voltage to the power transmission side first electrode and the power transmission side second electrode; the step-up transformer; the power transmission side first electrode; and the power transmission side second electrode; A first resonance circuit connected between the step-up transformer and a part of the step-up transformer, and the power reception device includes the power reception side first electrode and the power reception side second power. A piezoelectric transformer for stepping down a voltage induced by the second transformer circuit, and a second resonant circuit configured to include a part of an equivalent circuit of the piezoelectric transformer and having the same resonant frequency as the first resonant circuit, The power transmission device sweeps the drive frequency and detects a resonance frequency of the first resonance circuit and the second resonance circuit, and a resonance detected by the resonance frequency detection unit at a predetermined period. And a drive frequency setting unit that sets the frequency to the drive frequency.
圧電トランスを用いた場合、時間の経過に伴う自己発熱により、共振条件の特性変化が変化し、駆動周波数がずれるため伝送効率が低下するが、本発明の構成では、所定周期で駆動周波数を設定することで、伝送効率の低下を回避することができる。
When a piezoelectric transformer is used, due to self-heating with the passage of time, the characteristic change of the resonance condition changes and the drive frequency shifts, resulting in a decrease in transmission efficiency. However, in the configuration of the present invention, the drive frequency is set at a predetermined cycle. By doing so, it is possible to avoid a decrease in transmission efficiency.
前記駆動周波数設定部は、異なるタイミングで前記共振周波数検出部が検出した共振周波数の変化量が小さくなるに伴い、前記所定周期を長くすることが好ましい。
The drive frequency setting unit preferably lengthens the predetermined period as the amount of change in the resonance frequency detected by the resonance frequency detection unit at different timings decreases.
この構成では、共振周波数の変化量が小さいと、駆動周波数を設定する周期を長くすることで、無駄な電力伝送を回避し、電力伝送に伴う不要なノイズによる影響を防止できる。
In this configuration, if the amount of change in the resonance frequency is small, it is possible to avoid unnecessary power transmission by preventing the influence of unnecessary noise associated with power transmission by extending the period for setting the drive frequency.
前記送電装置は、前記インバータ回路に流れる電流を検出する電流検出部を備え、前記共振周波数検出部は、前記駆動周波数が掃引された時の、前記電流検出部により検出された電流値の周波数特性に基づいて、前記共振周波数を検出することが好ましい。
The power transmission device includes a current detection unit that detects a current flowing through the inverter circuit, and the resonance frequency detection unit has a frequency characteristic of a current value detected by the current detection unit when the drive frequency is swept. It is preferable to detect the resonance frequency based on the above.
この構成では、送電装置のインバータ回路に流れる電流を検出することで、共振周波数を検出するため、受電装置側の圧電トランスの状態を監視せずに共振周波数を検出できる。
In this configuration, since the resonance frequency is detected by detecting the current flowing through the inverter circuit of the power transmission device, the resonance frequency can be detected without monitoring the state of the piezoelectric transformer on the power reception device side.
前記送電装置は、前記受電装置へ伝送する伝送電力を検出する伝送電力検出部と、伝送電力に応じた前記第1の共振回路及び前記第2の共振回路の共振周波数の検出条件を記憶する記憶部と、を備え、前記共振周波数検出部は、前記伝送電力検出部が検出した伝送電力に応じた検出条件を前記記憶部から取得し、取得した検出条件と、前記駆動周波数を掃引したときに前記電流検出部が検出した電流値の周波数特性とに基づいて、共振周波数を検出することが好ましい。
The power transmission device stores a transmission power detection unit that detects transmission power to be transmitted to the power receiving device, and a memory that stores detection conditions for the resonance frequencies of the first resonance circuit and the second resonance circuit according to transmission power The resonance frequency detection unit acquires a detection condition according to the transmission power detected by the transmission power detection unit from the storage unit, and when the acquired detection condition and the drive frequency are swept It is preferable to detect the resonance frequency based on the frequency characteristic of the current value detected by the current detection unit.
電流検出部が検出した電流値の周波数特性は、伝送電力に応じて特性カーブが異なるため、上記構成のように、伝送電力に応じた共振周波数の検出条件を予め記憶しておくことで、伝送電力が変化しても、容易に適切な共振周波数を検出できる。
Since the frequency characteristic of the current value detected by the current detector has a different characteristic curve depending on the transmission power, the resonance frequency detection condition corresponding to the transmission power is stored in advance as in the above configuration. Even if the power changes, an appropriate resonance frequency can be easily detected.
本発明によれば、所定周期で駆動周波数を設定することで、伝送効率の低下を回避することができる。
According to the present invention, it is possible to avoid a decrease in transmission efficiency by setting the drive frequency at a predetermined cycle.
(実施形態1)
図1は、実施形態1に係る電力伝送システムの回路図である。図2は、図1の等価回路を示す図である。 (Embodiment 1)
FIG. 1 is a circuit diagram of a power transmission system according to the first embodiment. FIG. 2 is a diagram showing an equivalent circuit of FIG.
図1は、実施形態1に係る電力伝送システムの回路図である。図2は、図1の等価回路を示す図である。 (Embodiment 1)
FIG. 1 is a circuit diagram of a power transmission system according to the first embodiment. FIG. 2 is a diagram showing an equivalent circuit of FIG.
本実施形態に係る電力伝送システム1は、送電装置101と受電装置201とで構成されている。受電装置201は負荷回路RLを備えている。この負荷回路RLは充電回路及び二次電池を含む。そして、受電装置201は、その二次電池を備えた、例えば携帯電子機器である。携帯電子機器としては携帯電話機、PDA(Personal Digital Assistant)、携帯音楽プレーヤ、ノート型PC、デジタルカメラなどが挙げられる。送電装置101は、載置された受電装置201の二次電池を充電するための充電台である。
The power transmission system 1 according to this embodiment includes a power transmission device 101 and a power reception device 201. The power receiving apparatus 201 includes a load circuit RL. The load circuit RL includes a charging circuit and a secondary battery. And the power receiving apparatus 201 is a portable electronic device provided with the secondary battery, for example. Examples of portable electronic devices include cellular phones, PDAs (Personal Digital Assistants), portable music players, notebook PCs, and digital cameras. The power transmission device 101 is a charging stand for charging the secondary battery of the power receiving device 201 placed thereon.
送電装置101は、直流電圧Vinを出力する直流電源11を備えている。直流電源11は商用電源に接続されるACアダプタである。
The power transmission apparatus 101 includes a DC power supply 11 that outputs a DC voltage Vin. The DC power source 11 is an AC adapter connected to a commercial power source.
直流電源11にはインバータ回路12が接続されている。インバータ回路12は、MOS-FETのスイッチ素子Q1,Q2,Q3,Q4を備えている。インバータ回路12では、スイッチ素子Q1,Q2が直列接続され、スイッチ素子Q3,Q4が直列接続されている。また、スイッチ素子Q1,Q2の接続点とスイッチ素子Q3,Q4の接続点とは、昇圧トランスT1の1次コイルに接続されている。
The inverter circuit 12 is connected to the DC power source 11. The inverter circuit 12 includes MOS-FET switching elements Q1, Q2, Q3, and Q4. In the inverter circuit 12, switch elements Q1 and Q2 are connected in series, and switch elements Q3 and Q4 are connected in series. Further, the connection point of the switch elements Q1, Q2 and the connection point of the switch elements Q3, Q4 are connected to the primary coil of the step-up transformer T1.
インバータ回路12の各スイッチ素子Q1,Q2,Q3,Q4は、PWM制御回路15によりPWM制御される。なお、図2ではPWM制御回路15の図示は省略している。PWM制御回路15は、スイッチ素子Q1,Q4とスイッチ素子Q2,Q3とを交互にオンオフする。これにより、インバータ回路12は直流電圧Vinを交流電圧に変換する。
The switching elements Q1, Q2, Q3, and Q4 of the inverter circuit 12 are PWM-controlled by the PWM control circuit 15. In FIG. 2, the PWM control circuit 15 is not shown. The PWM control circuit 15 turns on and off the switch elements Q1 and Q4 and the switch elements Q2 and Q3 alternately. Thereby, the inverter circuit 12 converts the DC voltage Vin into an AC voltage.
PWM制御回路15は、出力電圧に応じて変動する帰還電圧と基準電圧との誤差電圧を増幅して誤差電圧信号を出力する誤差増幅器を備えている。そして、この誤差電圧信号と三角波との比較結果に応じたデューティのPWM信号を生成する。PWM制御回路15は、生成したPWM信号を、スイッチ素子Q1,Q2,Q3,Q4のゲートへ出力する。
The PWM control circuit 15 includes an error amplifier that amplifies the error voltage between the feedback voltage that varies according to the output voltage and the reference voltage and outputs an error voltage signal. Then, a PWM signal having a duty corresponding to the comparison result between the error voltage signal and the triangular wave is generated. The PWM control circuit 15 outputs the generated PWM signal to the gates of the switch elements Q1, Q2, Q3, and Q4.
送電装置101は制御回路16を備えている。制御回路16は、PWM制御回路15に、所定のデューティ比のPWM信号を生成させる。制御回路16については、後に詳述する。
The power transmission device 101 includes a control circuit 16. The control circuit 16 causes the PWM control circuit 15 to generate a PWM signal having a predetermined duty ratio. The control circuit 16 will be described in detail later.
昇圧トランスT1は、2次コイルがアクティブ電極13及びパッシブ電極14に接続されている。昇圧トランスT1は、インバータ回路12で変換された交流電圧を昇圧し、アクティブ電極13及びパッシブ電極14へ印加する。アクティブ電極13は、本発明に係る「送電側第1電極」の一例であり、パッシブ電極14は、本発明に係る「送電側第2電極」の一例である。
The step-up transformer T1 has a secondary coil connected to the active electrode 13 and the passive electrode 14. The step-up transformer T1 steps up the AC voltage converted by the inverter circuit 12 and applies it to the active electrode 13 and the passive electrode 14. The active electrode 13 is an example of the “power transmission side first electrode” according to the present invention, and the passive electrode 14 is an example of the “power transmission side second electrode” according to the present invention.
アクティブ電極13及びパッシブ電極14には、キャパシタC21,C22(図2では図示を省略)が直列接続されている。アクティブ電極13及びパッシブ電極14へ印加される電圧V1はキャパシタC21,C22により容量分圧される。制御回路16は、この容量分圧された交流電圧を整流し、前記電圧V1を検出する。
Capacitors C21 and C22 (not shown in FIG. 2) are connected in series to the active electrode 13 and the passive electrode 14. The voltage V1 applied to the active electrode 13 and the passive electrode 14 is capacitively divided by the capacitors C21 and C22. The control circuit 16 rectifies the AC voltage divided in capacity and detects the voltage V1.
また、パッシブ電極14には電流検出用の抵抗R1が接続されている。制御回路16は、抵抗R1に流れる電流I1を検出する。制御回路16は、この電流I1と電圧V1とから、送電装置101から受電装置201へ伝送する電力を取得する。
Further, a resistor R1 for current detection is connected to the passive electrode 14. The control circuit 16 detects a current I1 flowing through the resistor R1. The control circuit 16 acquires the power transmitted from the power transmission device 101 to the power reception device 201 from the current I1 and the voltage V1.
昇圧トランスT1の2次コイルにはキャパシタC1が並列に接続されていて、キャパシタC1は、昇圧トランスT1の2次コイルと共に並列共振回路17(図2参照)を形成している。
The capacitor C1 is connected in parallel to the secondary coil of the step-up transformer T1, and the capacitor C1 forms a parallel resonance circuit 17 (see FIG. 2) together with the secondary coil of the step-up transformer T1.
受電装置201はアクティブ電極23及びパッシブ電極24を備えている。アクティブ電極23及びパッシブ電極24は、受電装置201を送電装置101に載置した場合に、送電装置101のアクティブ電極13及びパッシブ電極14と間隙を介して対向する。アクティブ電極13及びパッシブ電極14間に電圧が印加されることで、対向配置となったアクティブ電極13,23が電界結合し、この結合を介して送電装置101の電極と受電装置201の電極が非接触の状態で送電装置101から受電装置201へ電力が伝送される。
The power receiving apparatus 201 includes an active electrode 23 and a passive electrode 24. The active electrode 23 and the passive electrode 24 face the active electrode 13 and the passive electrode 14 of the power transmission device 101 with a gap when the power receiving device 201 is placed on the power transmission device 101. When a voltage is applied between the active electrode 13 and the passive electrode 14, the active electrodes 13 and 23 that are arranged to face each other are subjected to electric field coupling, and the electrode of the power transmission device 101 and the electrode of the power reception device 201 are not connected via this coupling. Power is transmitted from the power transmitting apparatus 101 to the power receiving apparatus 201 in a contact state.
アクティブ電極23は、本発明に係る「受電側第1電極」の一例であり、パッシブ電極24は、本発明に係る「受電側第2電極」の一例である。
The active electrode 23 is an example of a “power receiving side first electrode” according to the present invention, and the passive electrode 24 is an example of a “power receiving side second electrode” according to the present invention.
受電装置201のアクティブ電極23及びパッシブ電極24には、圧電トランス22が接続されている。圧電トランス22は、一対の第1入力電極E11,E12と、一対の第2入力電極E21,E22とを有している。第1入力電極E11,E12は、アクティブ電極23に接続している。第2入力電極E21,E22は、パッシブ電極24に接続している。
The piezoelectric transformer 22 is connected to the active electrode 23 and the passive electrode 24 of the power receiving apparatus 201. The piezoelectric transformer 22 has a pair of first input electrodes E11 and E12 and a pair of second input electrodes E21 and E22. The first input electrodes E11 and E12 are connected to the active electrode 23. The second input electrodes E21 and E22 are connected to the passive electrode 24.
また、圧電トランス22は、一対の第1出力電極E31,E32、一対の第2出力電極E41,E42、及び一対の第3出力電極E51,E52を有している。第1出力電極E31,E32、第2出力電極E41,E42、及び第3出力電極E51,E52は、整流平滑回路25に接続している。圧電トランス22は、第1入力電極E11,E12及び第2入力電極E21,E22から入力される電圧を降圧し、第1出力電極E31,E32、第2出力電極E41,E42、及び第3出力電極E51,E52から整流平滑回路25へ出力する。
The piezoelectric transformer 22 includes a pair of first output electrodes E31 and E32, a pair of second output electrodes E41 and E42, and a pair of third output electrodes E51 and E52. The first output electrodes E31 and E32, the second output electrodes E41 and E42, and the third output electrodes E51 and E52 are connected to the rectifying and smoothing circuit 25. The piezoelectric transformer 22 steps down the voltage input from the first input electrodes E11 and E12 and the second input electrodes E21 and E22, and the first output electrodes E31 and E32, the second output electrodes E41 and E42, and the third output electrode. Output from E51 and E52 to the rectifying and smoothing circuit 25.
圧電トランス22は、図2に示すように、トランスT2、キャパシタC21,C22、キャパシタCp、インダクタLp及び抵抗Rp等で表される。キャパシタC21は圧電トランス22の等価入力容量であり、キャパシタC22は圧電トランス22の等価出力容量である。また、キャパシタCp及びインダクタLpは電気機械的なパラメータである。
As shown in FIG. 2, the piezoelectric transformer 22 is represented by a transformer T2, capacitors C21 and C22, a capacitor Cp, an inductor Lp, a resistor Rp, and the like. The capacitor C21 is an equivalent input capacity of the piezoelectric transformer 22, and the capacitor C22 is an equivalent output capacity of the piezoelectric transformer 22. The capacitor Cp and the inductor Lp are electromechanical parameters.
圧電トランス22の共振周波数は主にキャパシタCpとインダクタLpによる直列共振回路221の共振で定まる。電気エネルギー変換は弾性振動を介するため、圧電体セラミックスの弾性波伝搬速度と寸法で決まる固有共振周波数を有する。この圧電トランス22は、直列共振回路221が、送電装置101側に形成された並列共振回路17と共振周波数が同じとなるよう設計されている。
The resonance frequency of the piezoelectric transformer 22 is determined mainly by the resonance of the series resonance circuit 221 by the capacitor Cp and the inductor Lp. Since electrical energy conversion is via elastic vibration, it has a natural resonance frequency determined by the elastic wave propagation velocity and dimensions of the piezoelectric ceramic. The piezoelectric transformer 22 is designed such that the series resonance circuit 221 has the same resonance frequency as the parallel resonance circuit 17 formed on the power transmission device 101 side.
圧電トランス22の出力側には、インダクタL2が接続されていて、このインダクタL2は、圧電トランス22の等価出力容量であるキャパシタC22とによって並列共振回路222を構成している。インダクタL2は、この並列共振回路222が、並列共振回路17及び直列共振回路221と共振周波数が同じとなるよう回路定数が設定されている。
An inductor L 2 is connected to the output side of the piezoelectric transformer 22, and this inductor L 2 constitutes a parallel resonance circuit 222 with a capacitor C 22 that is an equivalent output capacity of the piezoelectric transformer 22. The inductor L2 has a circuit constant set so that the parallel resonant circuit 222 has the same resonance frequency as the parallel resonant circuit 17 and the series resonant circuit 221.
なお、電力伝送システム1で電力伝送をし続けると、圧電トランス22は自己発熱し、時間の経過と共に温度が上昇する。この発熱は、圧電トランス22のキャパシタCp等の等価的に表される各素子の定数に影響を及ぼす。本実施形態では、圧電トランス22が発熱していない状態(すなわち、圧電トランス22が冷めた状態)で、直列共振回路221及び並列共振回路222は、並列共振回路17と同じ共振周波数となるよう回路定数が設定されている。
In addition, if electric power transmission is continued by the electric power transmission system 1, the piezoelectric transformer 22 will self-heat, and temperature will rise with progress of time. This heat generation affects the constants of each element equivalently expressed such as the capacitor Cp of the piezoelectric transformer 22. In the present embodiment, the series resonance circuit 221 and the parallel resonance circuit 222 are configured so as to have the same resonance frequency as that of the parallel resonance circuit 17 in a state where the piezoelectric transformer 22 is not generating heat (that is, in a state where the piezoelectric transformer 22 is cooled). A constant is set.
圧電トランス22で降圧された電圧は、整流平滑回路25へ出力される。整流平滑回路25は、キャパシタ及びインダクタからなる平滑回路、ダイオードブリッジ、及び所定値の電圧に変換して出力するDC-DCコンバータ等を含んでいる。整流平滑回路25は、交流電圧を整流平滑し、負荷回路RLへ出力する。
The voltage stepped down by the piezoelectric transformer 22 is output to the rectifying / smoothing circuit 25. The rectifying / smoothing circuit 25 includes a smoothing circuit including a capacitor and an inductor, a diode bridge, and a DC-DC converter that converts the voltage into a predetermined value and outputs the voltage. The rectifying / smoothing circuit 25 rectifies and smoothes the AC voltage and outputs it to the load circuit RL.
なお、整流平滑回路25から負荷回路RLへ出力される出力電圧はVoutで表す。
The output voltage output from the rectifying / smoothing circuit 25 to the load circuit RL is represented by Vout.
図3は制御回路16の機能ブロック図である。制御回路16は、マイクロコンピュータを備え、IDC検出部161、伝送電力取得部162、周波数制御部163、記憶部164及び制御部165等の機能を有する。
FIG. 3 is a functional block diagram of the control circuit 16. The control circuit 16 includes a microcomputer and has functions such as an IDC detection unit 161, a transmission power acquisition unit 162, a frequency control unit 163, a storage unit 164, and a control unit 165.
IDC検出部161は送電電流IDCを検出する。詳しくは、直流電源11とインバータ回路12との間に電流検出用の抵抗R2が接続されていて、IDC検出部161は、その抵抗R2の降下電圧によりインバータ回路12に流れる送電電流IDCを検出する。IDC検出部161は、本発明に係る「電流検出部」に相当する。
The IDC detection unit 161 detects the transmission current IDC. Specifically, a resistance R2 for current detection is connected between the DC power supply 11 and the inverter circuit 12, and the IDC detection unit 161 detects the transmission current IDC flowing through the inverter circuit 12 by the voltage drop of the resistance R2. . The IDC detection unit 161 corresponds to a “current detection unit” according to the present invention.
伝送電力取得部162は、アクティブ電極13及びパッシブ電極14に印加される電圧V1と、アクティブ電極13及びパッシブ電極14に流れる電流I1とを取得し、電圧V1と電流I1とから、送電装置101から受電装置201への伝送電力を取得する。この伝送電力取得部162は、本発明に係る「伝送電力検出部」の一例である。
The transmission power acquisition unit 162 acquires the voltage V1 applied to the active electrode 13 and the passive electrode 14, and the current I1 flowing through the active electrode 13 and the passive electrode 14, and from the voltage V1 and the current I1, from the power transmission device 101. The transmission power to the power receiving apparatus 201 is acquired. The transmission power acquisition unit 162 is an example of the “transmission power detection unit” according to the present invention.
なお、送電装置101から受電装置201への伝送電力は、IDC検出部161が検出した送電電流IDCと入力電圧Vinとから求められてもよい。
Note that the transmission power from the power transmission apparatus 101 to the power reception apparatus 201 may be obtained from the transmission current IDC detected by the IDC detection unit 161 and the input voltage Vin.
周波数制御部163は、所定の駆動周波数でインバータ回路12がPWM制御されるよう、デューティ比をPWM制御回路15へ出力する。PWM制御回路15は、その入力されたデューティ比でインバータ回路12を制御する。また、周波数制御部163は、PWM制御回路15がインバータ回路12を駆動制御する周波数を掃引(スイープ)する。例えば、PWM制御回路15が470kHzの周波数でインバータ回路12をPWM制御している場合、468,469,470,471,472kHzと、470±2kHzの周波数範囲を1kHz刻みで掃引する。
The frequency control unit 163 outputs the duty ratio to the PWM control circuit 15 so that the inverter circuit 12 is PWM-controlled at a predetermined drive frequency. The PWM control circuit 15 controls the inverter circuit 12 with the input duty ratio. Further, the frequency control unit 163 sweeps (sweeps) the frequency at which the PWM control circuit 15 controls driving of the inverter circuit 12. For example, when the PWM control circuit 15 performs PWM control of the inverter circuit 12 at a frequency of 470 kHz, the frequency ranges of 468, 469, 470, 471, 472 kHz and 470 ± 2 kHz are swept in increments of 1 kHz.
記憶部164は、駆動周波数を設定する設定条件(検出条件)を記憶する。詳しくは、記憶部164は、送電装置101から受電装置201への伝送電力に応じて複数の設定条件を記憶している。この設定条件は、制御部165が、送電電流IDCの周波数特性から駆動周波数を設定する際に用いられる。
The storage unit 164 stores setting conditions (detection conditions) for setting the drive frequency. Specifically, the storage unit 164 stores a plurality of setting conditions according to the transmission power from the power transmission apparatus 101 to the power reception apparatus 201. This setting condition is used when the control unit 165 sets the drive frequency from the frequency characteristic of the transmission current IDC.
制御部165は、IDC検出部161、伝送電力取得部162、及び周波数制御部163それぞれの動作を制御する。制御部165は、周波数制御部163が周波数スイープしたときに、IDC検出部161が検出した送電電流IDC、すなわち、送電電流IDCの周波数特性に基づいて、駆動周波数を設定する。
The control unit 165 controls the operations of the IDC detection unit 161, the transmission power acquisition unit 162, and the frequency control unit 163. The control unit 165 sets the drive frequency based on the power transmission current IDC detected by the IDC detection unit 161 when the frequency control unit 163 performs frequency sweep, that is, based on the frequency characteristics of the power transmission current IDC.
送電電流IDCの周波数特性は、図4に示すように、伝送電力によって特性カーブの凹凸が異なる。図4は、送電電流IDCの周波数特性を示す図である。図4の横軸は周波数、縦軸は送電電流IDCであり、負荷回路RLの負荷を変化させた場合の特性を示す。図4に示すように、負荷の大きさに応じて周波数特性の特性カーブが異なる。
As shown in FIG. 4, the frequency characteristic of the transmission current IDC varies depending on the transmission power. FIG. 4 is a diagram illustrating frequency characteristics of the transmission current IDC. The horizontal axis in FIG. 4 is the frequency, and the vertical axis is the transmission current IDC, and shows characteristics when the load of the load circuit RL is changed. As shown in FIG. 4, the characteristic curve of the frequency characteristic varies depending on the size of the load.
記憶部164に記憶されている設定条件では、例えば、得られた周波数特性の特性カーブの極大値をとる周波数を駆動周波数に設定するのか、極小値をとる周波数を駆動周波数に設定するのかのかが定められている。制御部165は、伝送電力取得部162が取得した伝送電力に対応する設定条件を記憶部164から取得し、その設定条件と、送電電流IDCの周波数特性とから駆動周波数を設定する。そして、周波数制御部163が、その駆動周波数でPWM制御回路15がインバータ回路12をPWM制御するよう、PWM制御回路15へデューティ比を出力する。このように、予め伝送電力に対応する設定条件が記憶されているため、伝送電力が変化しても、容易に適切な共振周波数を検出できる。
In the setting conditions stored in the storage unit 164, for example, whether the frequency that takes the maximum value of the obtained characteristic curve of the frequency characteristic is set as the driving frequency or the frequency that takes the minimum value is set as the driving frequency. It has been established. The control unit 165 acquires the setting condition corresponding to the transmission power acquired by the transmission power acquisition unit 162 from the storage unit 164, and sets the drive frequency from the setting condition and the frequency characteristic of the transmission current IDC. Then, the frequency control unit 163 outputs a duty ratio to the PWM control circuit 15 so that the PWM control circuit 15 performs PWM control of the inverter circuit 12 at the drive frequency. Thus, since the setting conditions corresponding to the transmission power are stored in advance, an appropriate resonance frequency can be easily detected even if the transmission power changes.
制御部165は、本発明に係る「共振周波数検出部」、及び「駆動周波数設定部」の一例である。
The control unit 165 is an example of a “resonance frequency detection unit” and a “drive frequency setting unit” according to the present invention.
以下に、受電装置201で用いられる圧電トランス22について説明する。
Hereinafter, the piezoelectric transformer 22 used in the power receiving apparatus 201 will be described.
図5は、圧電トランス22の斜視図である。図6は、図5のVI-VI線における断面図である。図7は、図5のVII-VII線における断面図である。
FIG. 5 is a perspective view of the piezoelectric transformer 22. 6 is a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a sectional view taken along line VII-VII in FIG.
圧電トランス22は矩形板状の圧電体板30を備えている。この圧電体板30は、例えばPZT系セラミックスシートが積層されて形成されている。以下では、圧電トランス22の長さ方向をX軸方向、幅方向をY軸方向、厚み方向をZ軸方向とする
圧電トランス22は、(7λ/2)共振モードで長さ方向に振動するものとする。ここで、λは長さ方向の振動の1波長である。したがって、圧電トランス22のX軸方向の長さは(7λ/2)としている。ここで、Y軸方向の幅及びZ軸方向の厚みは(λ/2)未満とすることが好ましい。そうすることで、幅方向及び厚み方向の振動が長さ方向の振動に結合せず、圧電トランス22全体の振動が不安定とならない。 Thepiezoelectric transformer 22 includes a rectangular plate-shaped piezoelectric plate 30. The piezoelectric plate 30 is formed by stacking, for example, PZT ceramic sheets. Below, the length direction of the piezoelectric transformer 22 is the X-axis direction, the width direction is the Y-axis direction, and the thickness direction is the Z-axis direction. The piezoelectric transformer 22 vibrates in the length direction in the (7λ / 2) resonance mode. And Here, λ is one wavelength of vibration in the length direction. Therefore, the length of the piezoelectric transformer 22 in the X-axis direction is set to (7λ / 2). Here, the width in the Y-axis direction and the thickness in the Z-axis direction are preferably less than (λ / 2). By doing so, the vibration in the width direction and the thickness direction is not coupled to the vibration in the length direction, and the vibration of the entire piezoelectric transformer 22 is not unstable.
圧電トランス22は、(7λ/2)共振モードで長さ方向に振動するものとする。ここで、λは長さ方向の振動の1波長である。したがって、圧電トランス22のX軸方向の長さは(7λ/2)としている。ここで、Y軸方向の幅及びZ軸方向の厚みは(λ/2)未満とすることが好ましい。そうすることで、幅方向及び厚み方向の振動が長さ方向の振動に結合せず、圧電トランス22全体の振動が不安定とならない。 The
圧電体板30は、X軸方向に沿って、第1低電圧領域31、第1高電圧領域32、第2高電圧領域33、第2低電圧領域34、第3高電圧領域35、第4高電圧領域36、及び第3低電圧領域37が形成されている。各領域31~37のX軸方向の長さは、何れもλ/2である。
The piezoelectric plate 30 includes a first low voltage region 31, a first high voltage region 32, a second high voltage region 33, a second low voltage region 34, a third high voltage region 35, a fourth, along the X-axis direction. A high voltage region 36 and a third low voltage region 37 are formed. The lengths in the X-axis direction of the regions 31 to 37 are all λ / 2.
第1低電圧領域31、第2低電圧領域34及び第3低電圧領域37は、Z軸方向(厚み方向)に分極されている。第1低電圧領域31と第3低電圧領域37とは同方向に分極され、第2低電圧領域34は、第1低電圧領域31及び第3低電圧領域37と逆方向に分極されている。分極処理の方法としては、例えば、圧電体板を170℃の絶縁油中で2kV/mmの電圧を印加する方法等が挙げられる。
The first low voltage region 31, the second low voltage region 34, and the third low voltage region 37 are polarized in the Z-axis direction (thickness direction). The first low voltage region 31 and the third low voltage region 37 are polarized in the same direction, and the second low voltage region 34 is polarized in the opposite direction to the first low voltage region 31 and the third low voltage region 37. . Examples of the polarization treatment method include a method of applying a voltage of 2 kV / mm to the piezoelectric plate in insulating oil at 170 ° C.
第1低電圧領域31には、一対の第1出力電極E31,E32がY軸方向に対向するよう圧電体板30の側面に設けられている。また、第1低電圧領域31には、Z軸方向に積層された複数の内部電極E33が設けられている。この内部電極E33は、図6に示すように、交互に第1出力電極E31,E32に接続している。
In the first low voltage region 31, a pair of first output electrodes E31 and E32 are provided on the side surface of the piezoelectric plate 30 so as to face each other in the Y-axis direction. The first low voltage region 31 is provided with a plurality of internal electrodes E33 stacked in the Z-axis direction. As shown in FIG. 6, the internal electrodes E33 are alternately connected to the first output electrodes E31 and E32.
同様に、第2低電圧領域34、及び、第3低電圧領域37には、一対の第2出力電極E41,E42、及び、第3出力電極E51,E52がY軸方向に対向するよう圧電体板30の側面に設けられている。また、第2低電圧領域34、及び、第3低電圧領域37には、Z軸方向に積層された複数の内部電極E43,E53が設けられている。この内部電極E43は、交互に第2出力電極E41,E42に接続し、内部電極E53は、交互に第3出力電極E51,E52に接続している。
Similarly, in the second low voltage region 34 and the third low voltage region 37, the pair of second output electrodes E41 and E42 and the third output electrodes E51 and E52 are arranged so as to face each other in the Y-axis direction. It is provided on the side surface of the plate 30. The second low voltage region 34 and the third low voltage region 37 are provided with a plurality of internal electrodes E43 and E53 stacked in the Z-axis direction. The internal electrodes E43 are alternately connected to the second output electrodes E41 and E42, and the internal electrodes E53 are alternately connected to the third output electrodes E51 and E52.
第1高電圧領域32、第2高電圧領域33、第3高電圧領域35及び第4高電圧領域36は、X軸方向に分極されている。第1高電圧領域32には、一対の第2入力電極E21,E22がY軸方向に対向するよう圧電体板30の側面に設けられている。また、第1高電圧領域32には、Z軸方向に積層された複数の内部電極E23が設けられている。この内部電極E23は、第2入力電極E21,E22それぞれに接続している。
The first high voltage region 32, the second high voltage region 33, the third high voltage region 35, and the fourth high voltage region 36 are polarized in the X-axis direction. In the first high voltage region 32, a pair of second input electrodes E21 and E22 are provided on the side surface of the piezoelectric plate 30 so as to face each other in the Y-axis direction. The first high voltage region 32 is provided with a plurality of internal electrodes E23 stacked in the Z-axis direction. The internal electrode E23 is connected to each of the second input electrodes E21 and E22.
第4高電圧領域36には、一対の第1入力電極E11,E12がY軸方向に対向するよう圧電体板30の側面に設けられている。また、第4高電圧領域36には、Z軸方向に積層された複数の内部電極E13が設けられている。この内部電極E13は、第1入力電極E11,E12それぞれに接続している。
In the fourth high voltage region 36, a pair of first input electrodes E11 and E12 are provided on the side surface of the piezoelectric plate 30 so as to face each other in the Y-axis direction. The fourth high voltage region 36 is provided with a plurality of internal electrodes E13 stacked in the Z-axis direction. The internal electrode E13 is connected to each of the first input electrodes E11 and E12.
以上のように構成された圧電トランス22において、第1入力電極E11,E12がアクティブ電極23に接続され、また、第2入力電極E21,E22がパッシブ電極24に接続されている。送電装置101から受電装置201へ電力伝送され、アクティブ電極23及びパッシブ電極24に電圧が誘起すると、第1入力電極E11,E12及び第2入力電極E21,E22によって、圧電体板30のX軸方向(長さ方向)に電圧が印加される。このため、第1高電圧領域32、第2高電圧領域33、第3高電圧領域35及び第4高電圧領域36には分極方向に電界が加えられる。そして、逆圧電効果により分極方向に直交する方向、すなわち、圧電体板30のX軸方向に縦振動が励振される。
In the piezoelectric transformer 22 configured as described above, the first input electrodes E11 and E12 are connected to the active electrode 23, and the second input electrodes E21 and E22 are connected to the passive electrode 24. When power is transmitted from the power transmitting apparatus 101 to the power receiving apparatus 201 and a voltage is induced in the active electrode 23 and the passive electrode 24, the first input electrodes E11 and E12 and the second input electrodes E21 and E22 cause the piezoelectric plate 30 to move in the X-axis direction. A voltage is applied in the length direction. Therefore, an electric field is applied to the first high voltage region 32, the second high voltage region 33, the third high voltage region 35, and the fourth high voltage region 36 in the polarization direction. Then, longitudinal vibration is excited in the direction orthogonal to the polarization direction by the inverse piezoelectric effect, that is, in the X-axis direction of the piezoelectric plate 30.
縦振動が励振されると、第1低電圧領域31、第2低電圧領域34及び第3低電圧領域37ではZ軸方向(分極方向)に機械的歪みが生じ、圧電横効果により分極方向に電位差が発生する。この電位差により第1低電圧領域31、第2低電圧領域34及び第3低電圧領域37が低電圧部となり、各電極から低電圧が取り出され負荷回路RLに印加される。
When longitudinal vibration is excited, mechanical distortion occurs in the Z-axis direction (polarization direction) in the first low-voltage region 31, the second low-voltage region 34, and the third low-voltage region 37, and in the polarization direction due to the piezoelectric transverse effect. A potential difference occurs. Due to this potential difference, the first low voltage region 31, the second low voltage region 34, and the third low voltage region 37 become a low voltage portion, and a low voltage is extracted from each electrode and applied to the load circuit RL.
以上のように構成された電力伝送システム1では、並列共振回路17、直列共振回路221及び並列共振回路222それぞれは、共振周波数が同じになるよう回路定数が設定されている。本実施形態では、共振周波数は470kHzとする。そして、駆動周波数は、その共振周波数に定められる。共振周波数において、並列共振回路17と並列共振回路222とはハイインピーダンス(極大)となり、直列共振回路221はローインピーダンス(極小)となる。このため、並列共振回路17、直列共振回路221及び並列共振回路222における電圧降下、すなわち、インバータ回路12と負荷回路RLとの間での電圧降下は小さい。
In the power transmission system 1 configured as described above, the circuit constants are set so that the parallel resonant circuit 17, the series resonant circuit 221, and the parallel resonant circuit 222 have the same resonant frequency. In the present embodiment, the resonance frequency is 470 kHz. The drive frequency is determined by the resonance frequency. At the resonance frequency, the parallel resonance circuit 17 and the parallel resonance circuit 222 have high impedance (maximum), and the series resonance circuit 221 has low impedance (minimum). For this reason, the voltage drop in the parallel resonant circuit 17, the series resonant circuit 221 and the parallel resonant circuit 222, that is, the voltage drop between the inverter circuit 12 and the load circuit RL is small.
図8は、送電装置101の出力電圧に対する受電装置201の出力電圧Voutの比率(電圧変換比)の周波数特性を示す図である。送電装置101の出力電圧は、すなわち、キャパシタC21,C22により容量分圧され、アクティブ電極13及びパッシブ電極14に印加される電圧V1である。図8の横軸は周波数、縦軸は変圧比(Vout/V1)であり、負荷回路RLの負荷を変化させた場合の特性を示す。
FIG. 8 is a diagram illustrating a frequency characteristic of a ratio (voltage conversion ratio) of the output voltage Vout of the power receiving device 201 with respect to the output voltage of the power transmitting device 101. In other words, the output voltage of the power transmission device 101 is a voltage V1 that is capacity-divided by the capacitors C21 and C22 and applied to the active electrode 13 and the passive electrode 14. The horizontal axis in FIG. 8 is the frequency, and the vertical axis is the transformation ratio (Vout / V1), which shows the characteristics when the load of the load circuit RL is changed.
図8では、周波数が約470kHzの場合、負荷に関係なく変圧比は略同じである。したがって、並列共振回路17、直列共振回路221及び並列共振回路222の共振周波数が約470kHzとなるよう回路定数を設定し、その共振周波数を駆動周波数に定めることで、負荷変動に関係になく、電圧変動を小さくできる。すなわち、負荷変動に関係なく、効率の良い電力伝送が可能となる。
In FIG. 8, when the frequency is about 470 kHz, the transformation ratio is substantially the same regardless of the load. Therefore, the circuit constant is set so that the resonance frequency of the parallel resonance circuit 17, the series resonance circuit 221 and the parallel resonance circuit 222 is about 470 kHz, and the resonance frequency is set as the drive frequency, so that the voltage is not related to the load fluctuation. Variation can be reduced. That is, efficient power transmission is possible regardless of load fluctuations.
前記したように、電力伝送システム1で電力伝送をし続けることで、圧電トランス22は自己発熱するため、共振条件がずれる。このため、時間の経過に伴い、共振周波数が駆動周波数からずれていき、伝送効率が低下する。そこで、本実施形態では、周期的に共振周波数を検出し、駆動周波数を随時補正する。
As described above, since the piezoelectric transformer 22 self-heats by continuing to transmit power in the power transmission system 1, the resonance condition is deviated. For this reason, with the passage of time, the resonance frequency deviates from the drive frequency, and the transmission efficiency decreases. Therefore, in this embodiment, the resonance frequency is periodically detected and the drive frequency is corrected as needed.
以下に、駆動周波数の設定方法について説明する。
The following explains how to set the drive frequency.
図9は、制御部165が実行する処理を示すフローチャートである。図9に示す処理は、例えば、送電装置101に受電装置201が載置されることで開始される。
FIG. 9 is a flowchart showing processing executed by the control unit 165. The process illustrated in FIG. 9 is started, for example, when the power receiving apparatus 201 is placed on the power transmitting apparatus 101.
制御部165は、図10に示す駆動周波数設定処理を実行する(S1)。図10は、駆動周波数設定処理を示すフローチャートである。周波数制御部163は、インバータ回路12の各スイッチ素子Q1~Q4をPWM制御し、インバータ回路12の出力電圧の周波数をスイープする(S11)。例えば、現周波数が470kHzである場合、468,469,470,471,472kHzと、468kHzから472kHzまで1kHz刻みで掃引する。
The control unit 165 executes the drive frequency setting process shown in FIG. 10 (S1). FIG. 10 is a flowchart showing the drive frequency setting process. The frequency control unit 163 performs PWM control on the switch elements Q1 to Q4 of the inverter circuit 12 and sweeps the frequency of the output voltage of the inverter circuit 12 (S11). For example, when the current frequency is 470 kHz, sweeping is performed in increments of 1 kHz from 468 kHz to 472 kHz, 468, 469, 470, 471, 472 kHz.
周波数制御部163が周波数スイープをするごとに、IDC検出部161が送電電流IDCを検出して、制御部165は、送電電流IDCの周波数特性を取得する(S12)。制御部165は、アクティブ電極13及びパッシブ電極14に印加される電圧V1と、アクティブ電極13及びパッシブ電極14に流れる電流I1とから、送電装置101から受電装置201への伝送電力を取得する(S13)。制御部165は、伝送電力に対向する設定条件を記憶部164から取得する(S14)。制御部165は、S12で取得した周波数特性と、S14で取得した設定条件とから駆動周波数を設定する(S15)。
Each time the frequency control unit 163 performs a frequency sweep, the IDC detection unit 161 detects the transmission current IDC, and the control unit 165 acquires the frequency characteristics of the transmission current IDC (S12). The control unit 165 acquires transmission power from the power transmission apparatus 101 to the power reception apparatus 201 from the voltage V1 applied to the active electrode 13 and the passive electrode 14 and the current I1 flowing through the active electrode 13 and the passive electrode 14 (S13). ). The control unit 165 acquires a setting condition opposite to the transmission power from the storage unit 164 (S14). The control unit 165 sets the drive frequency from the frequency characteristic acquired in S12 and the setting condition acquired in S14 (S15).
送電電流IDCの周波数特性の特性カーブは、伝送電力に応じて異なる。このため、伝送電力に応じた設定条件に従い共振周波数を検出し、その検出した共振周波数を駆動周波数に設定する。例えば、図4に示す周波数特性において、検出により得られた周波数特性が、特性カーブRC1であり、取得した設定条件が得られた周波数の極大値を駆動周波数と設定するという条件である場合、図4に示す特性カーブRC1の極大値、すなわち、周波数470kHzを駆動周波数に設定する。また、検出により得られた周波数特性が、特性カーブRC2であり、取得した設定条件が得られた周波数の極小値を駆動周波数と設定するという条件である場合、図4に示す特性カーブRC2の極小値、すなわち、周波数470kHzを駆動周波数に設定する。
The characteristic curve of the frequency characteristic of the transmission current IDC varies depending on the transmission power. For this reason, the resonance frequency is detected according to the setting condition corresponding to the transmission power, and the detected resonance frequency is set as the drive frequency. For example, in the frequency characteristic shown in FIG. 4, when the frequency characteristic obtained by the detection is the characteristic curve RC1, and the acquired setting condition is a condition that the maximum value of the obtained frequency is set as the drive frequency, FIG. The maximum value of the characteristic curve RC1 shown in FIG. 4, that is, the frequency of 470 kHz is set as the drive frequency. Further, when the frequency characteristic obtained by detection is the characteristic curve RC2, and the acquired setting condition is a condition that the minimum value of the obtained frequency is set as the drive frequency, the minimum of the characteristic curve RC2 shown in FIG. A value, that is, a frequency of 470 kHz is set as a driving frequency.
図9に戻り、制御部165は処理を終了するか否かを判定する(S2)。処理を終了する場合とは、例えば、送電装置101から受電装置201が取り外された場合などである。処理を終了する場合(S2:YES)、本処理は終了する。処理を終了しない場合(S2:NO)、制御部165は、駆動周波数を設定してから時間Tが経過したか否かを判定する(S3)。この時間Tは、例えば10sなど、適宜変更可能である。
Returning to FIG. 9, the control unit 165 determines whether or not to end the process (S2). The case where the process is terminated is, for example, a case where the power receiving apparatus 201 is removed from the power transmitting apparatus 101. When the process ends (S2: YES), this process ends. When the process is not terminated (S2: NO), the control unit 165 determines whether or not the time T has elapsed since the drive frequency was set (S3). This time T can be appropriately changed, for example, 10 s.
時間Tが経過していない場合(S3:NO)、制御部165はS2の処理を実行する。時間Tが経過した場合(S3:YES)、制御部165は駆動周波数設定処理を実行する(S4)。この駆動周波数設定処理は、図10に示す処理である。このように、本実施形態では、時間T毎に、駆動周波数を設定する。
When the time T has not elapsed (S3: NO), the control unit 165 executes the process of S2. When the time T has elapsed (S3: YES), the control unit 165 executes a drive frequency setting process (S4). This drive frequency setting process is the process shown in FIG. Thus, in the present embodiment, the drive frequency is set every time T.
電力伝送を連続して行うと、時間経過と共に圧電トランス22が自己発熱し、その影響で共振周波数が変動する。このため、時間が経過しても常に同じ駆動周波数で電力伝送し続けた場合、効率が低下する。そこで、時間T毎に駆動周波数を再設定(補正)する。これにより、圧電トランス22の共振周波数がずれても、そのずれに応じて駆動周波数が再設定されるので、効率よく電力伝送し続けることができる。
When the power transmission is continuously performed, the piezoelectric transformer 22 self-heats with time, and the resonance frequency fluctuates due to the influence. For this reason, if power is always transmitted at the same drive frequency even after time has passed, the efficiency decreases. Therefore, the drive frequency is reset (corrected) every time T. Thereby, even if the resonance frequency of the piezoelectric transformer 22 is deviated, the drive frequency is reset according to the deviation, so that power can be transmitted efficiently.
再設定後、制御部165は、再設定前後の駆動周波数の差分が閾値(例えば、50mV)以上であるか否かを判定する(S5)。閾値以上の場合(S5:YES)、制御部165は、S2の処理を実行する。閾値以上でない場合(S5:NO)、制御部165は、TをT1(T1>t)とする(S6)。
After the resetting, the control unit 165 determines whether or not the difference between the driving frequencies before and after the resetting is greater than or equal to a threshold value (for example, 50 mV) (S5). If it is equal to or greater than the threshold (S5: YES), the control unit 165 executes the process of S2. When it is not more than a threshold value (S5: NO), the control part 165 sets T to T1 (T1> t) (S6).
送電装置101から受電装置201へは大電力が伝送される。このため、短期間で繰り返し、駆動周波数設定処理を行うと、電力伝送による不要ノイズが発生し、送電装置101及び受電装置201に影響が及ぶおそれがある。そこで、周期的に検出する共振周波数の変化に差がない場合には、駆動周波数設定処理を行う周期を長くすることで、不要ノイズによる影響を防止できる。
High power is transmitted from the power transmitting apparatus 101 to the power receiving apparatus 201. For this reason, if the drive frequency setting process is repeatedly performed in a short period, unnecessary noise due to power transmission may occur, which may affect the power transmission apparatus 101 and the power reception apparatus 201. Therefore, when there is no difference in the change in the resonance frequency detected periodically, the influence of unnecessary noise can be prevented by lengthening the period for performing the drive frequency setting process.
以上説明したように、本実施形態では、圧電トランス22の自己発熱に伴い、伝送効率が低下するため、周期的に共振周波数を検出し、駆動周波数を再設定することで、伝送効率の低下を抑制できる。また、圧電トランス22の自己発熱に伴い共振周波数がずれるが、本実施形態では、送電装置101で送電電流IDCから共振周波数を検出するため、受電装置201側の圧電トランス22を監視する必要がない。
As described above, in this embodiment, since the transmission efficiency is reduced due to self-heating of the piezoelectric transformer 22, the transmission efficiency is reduced by periodically detecting the resonance frequency and resetting the drive frequency. Can be suppressed. Further, although the resonance frequency shifts with self-heating of the piezoelectric transformer 22, in this embodiment, since the resonance frequency is detected from the transmission current IDC by the power transmission apparatus 101, it is not necessary to monitor the piezoelectric transformer 22 on the power reception apparatus 201 side. .
なお、本実施形態では、周波数特性の特性カーブの極大値又は極小値を共振周波数とする場合について説明したが、共振周波数の検出する方法はこれに限定されない。例えば、周波数スイープしたときにIDC検出部161が検出した送電電流IDCから傾きを求め、その傾きの反転を検出することによって共振周波数を検出するようにしてもよい。周波数スイープしたときの送電電流IDCの変位量から共振周波数を検出するようにしてもよい。
In the present embodiment, the case where the maximum value or the minimum value of the characteristic curve of the frequency characteristic is the resonance frequency has been described, but the method for detecting the resonance frequency is not limited to this. For example, the resonance frequency may be detected by obtaining an inclination from the transmission current IDC detected by the IDC detection unit 161 when frequency sweeping is performed, and detecting inversion of the inclination. The resonance frequency may be detected from the amount of displacement of the transmission current IDC when the frequency is swept.
また、本実施形態では、圧電トランス22が発熱していない状態(すなわち、圧電トランス22が冷めた状態)で回路定数を設定しているが、圧電トランス22が発熱した状態(圧電トランス22の温度が上がっている状態)で回路定数を設定するようにしてもよい。この場合であっても、周期的に共振周波数を検出し、駆動周波数を設定することで、伝送効率の低下を抑制できる。
In the present embodiment, the circuit constants are set in a state where the piezoelectric transformer 22 is not generating heat (that is, in a state where the piezoelectric transformer 22 is cooled), but in a state where the piezoelectric transformer 22 is generating heat (temperature of the piezoelectric transformer 22). The circuit constant may be set in a state where the Even in this case, a decrease in transmission efficiency can be suppressed by periodically detecting the resonance frequency and setting the drive frequency.
(実施形態2)
図11は、実施形態2に係る電力伝送システムの回路図である。本実施形態に係る電力伝送システム2は、送電装置102と受電装置201とを備えている。受電装置201は、実施形態1と同じである。 (Embodiment 2)
FIG. 11 is a circuit diagram of a power transmission system according to the second embodiment. Thepower transmission system 2 according to the present embodiment includes a power transmission device 102 and a power reception device 201. The power receiving apparatus 201 is the same as that in the first embodiment.
図11は、実施形態2に係る電力伝送システムの回路図である。本実施形態に係る電力伝送システム2は、送電装置102と受電装置201とを備えている。受電装置201は、実施形態1と同じである。 (Embodiment 2)
FIG. 11 is a circuit diagram of a power transmission system according to the second embodiment. The
本実施形態に係る送電装置102は、実施形態1に係る送電装置101と同様に、直流電源11、インバータ回路12、昇圧トランスT1、アクティブ電極13及びパッシブ電極14を備えている。昇圧トランスT1の2次コイルには、キャパシタC3が接続されている。キャパシタC3は、昇圧トランスT1の漏れインダクタンス(又は実部品のインダクタ)L1と共に直列共振回路18を構成している。この直列共振回路18は、その共振周波数が、受電装置201の共振回路221,222(図2参照)の共振周波数になるよう回路定数が設定されている。すなわち、実施形態1では、送電装置101に並列共振回路17が形成しているのに対し、本実施形態では、送電装置102に直列共振回路18を形成している点で実施形態1と相違する。
The power transmission device 102 according to the present embodiment includes a DC power supply 11, an inverter circuit 12, a step-up transformer T1, an active electrode 13, and a passive electrode 14 as with the power transmission device 101 according to the first embodiment. A capacitor C3 is connected to the secondary coil of the step-up transformer T1. The capacitor C3 forms a series resonance circuit 18 together with the leakage inductance (or the actual inductor) L1 of the step-up transformer T1. The series resonance circuit 18 has a circuit constant set so that the resonance frequency thereof becomes the resonance frequency of the resonance circuits 221 and 222 (see FIG. 2) of the power receiving apparatus 201. That is, in the first embodiment, the parallel resonance circuit 17 is formed in the power transmission device 101, whereas in this embodiment, the series resonance circuit 18 is formed in the power transmission device 102, which is different from the first embodiment. .
送電装置102の直列共振回路18と、受電装置201の直列共振回路221及び並列共振回路222との共振周波数が、同じになるよう回路定数を設定することで、その共振周波数において、並列共振回路222はハイインピーダンス(極大)となり、直列共振回路18と直列共振回路221はローインピーダンス(極小)となる。このため、直列共振回路18、直列共振回路221及び並列共振回路222における電圧降下、すなわち、インバータ回路12と負荷回路RLとの間での電圧降下は小さい。
By setting circuit constants so that the resonance frequencies of the series resonance circuit 18 of the power transmission apparatus 102 and the series resonance circuit 221 and the parallel resonance circuit 222 of the power reception apparatus 201 are the same, the parallel resonance circuit 222 is set at the resonance frequency. Becomes high impedance (maximum), and the series resonance circuit 18 and the series resonance circuit 221 become low impedance (minimum). For this reason, the voltage drop in the series resonant circuit 18, the series resonant circuit 221 and the parallel resonant circuit 222, that is, the voltage drop between the inverter circuit 12 and the load circuit RL is small.
図12は、送電電流IDCの周波数特性を示す図である。図4の横軸は周波数、縦軸は送電電流IDCであり、負荷回路RLの負荷を変化させた場合の特性を示す。図4に示すように、送電装置102が直列共振回路18を備えている場合であっても、負荷に応じて周波数特性の特性カーブが異なる。したがって、実施形態1と同様に、伝送電力に応じた設定条件に従い共振周波数を検出し、その検出した共振周波数を駆動周波数に設定する。
FIG. 12 is a diagram showing the frequency characteristics of the transmission current IDC. The horizontal axis in FIG. 4 is the frequency, and the vertical axis is the transmission current IDC, and shows characteristics when the load of the load circuit RL is changed. As shown in FIG. 4, even when the power transmission device 102 includes the series resonance circuit 18, the frequency characteristic curve varies depending on the load. Therefore, similarly to the first embodiment, the resonance frequency is detected according to the setting condition corresponding to the transmission power, and the detected resonance frequency is set as the drive frequency.
例えば、図12に示す周波数特性において、検出により得られた周波数特性が、図に示す特性カーブRC3であり、取得した設定条件が得られた周波数の極小値を駆動周波数と設定するという条件である場合、図12に示す特性カーブRC3の極小値、すなわち、周波数470kHzを駆動周波数に設定する。また、図12に示す周波数特性において、検出により得られた周波数特性が、図に示す特性カーブRC4であり、取得した設定条件が得られた周波数の極大値を駆動周波数と設定するという条件である場合、図12に示す特性カーブRC4の極小値、すなわち、周波数470kHzを駆動周波数に設定する。何れの場合でも、駆動周波数を周波数470kHzに設定できる。
For example, in the frequency characteristic shown in FIG. 12, the frequency characteristic obtained by detection is the characteristic curve RC3 shown in the figure, and the obtained setting condition is a condition that the minimum value of the obtained frequency is set as the drive frequency. In this case, the minimum value of the characteristic curve RC3 shown in FIG. 12, that is, the frequency of 470 kHz is set as the drive frequency. Further, in the frequency characteristic shown in FIG. 12, the frequency characteristic obtained by detection is the characteristic curve RC4 shown in the figure, and the obtained setting condition is a condition that the maximum value of the obtained frequency is set as the drive frequency. In this case, the minimum value of the characteristic curve RC4 shown in FIG. 12, that is, the frequency 470 kHz is set as the drive frequency. In either case, the drive frequency can be set to a frequency of 470 kHz.
これにより、実施形態1の図8で説明したように、例えば、共振周波数が約470kHzとした場合、その共振周波数における、送電装置102の出力電圧に対する受電装置201の出力電圧の電圧変換比は、負荷に関係なく変圧比は略同じとなる。すなわち、負荷変動に関係になく、効率の良い電力伝送が可能となる。
Thereby, as described in FIG. 8 of the first embodiment, for example, when the resonance frequency is about 470 kHz, the voltage conversion ratio of the output voltage of the power receiving apparatus 201 to the output voltage of the power transmission apparatus 102 at the resonance frequency is The transformation ratio is almost the same regardless of the load. That is, efficient power transmission is possible regardless of load fluctuations.
この回路において、実施形態1と同様に、共振周波数を周期的に検出し、その検出した共振周波数を駆動周波数に設定することで、圧電トランス22が自己発熱した場合であっても、伝送効率を低下させることなく電力伝送できる。
In this circuit, similarly to the first embodiment, by periodically detecting the resonance frequency and setting the detected resonance frequency as the drive frequency, even if the piezoelectric transformer 22 self-heats, the transmission efficiency is improved. Electric power can be transmitted without degrading.
C1…キャパシタ
C21,C22…キャパシタ
C3…キャパシタ
Cp…キャパシタ
E11,E12…第1入力電極
E13…内部電極
E21,E22…第2入力電極
E23…内部電極
E31,E32…第1出力電極
E33…内部電極
E41,E42…第2出力電極
E43…内部電極
E51,E52…第3出力電極
E53…内部電極
L1…漏れインダクタンス
L2…インダクタ
Lp…インダクタ
Q1,Q2,Q3,Q4…スイッチ素子
R1,R2…抵抗
RL…負荷回路
Rp…抵抗
T1…昇圧トランス
T2…トランス
1,2…電力伝送システム
11…直流電源
12…インバータ回路
13,23…アクティブ電極
14,24…パッシブ電極
15…PWM制御回路
16…制御回路
17…並列共振回路
18…直列共振回路
22…圧電トランス
25…整流平滑回路
30…圧電体板
31…第1低電圧領域
32…第1高電圧領域
33…第2高電圧領域
34…第2低電圧領域
35…第3高電圧領域
36…第4高電圧領域
37…第3低電圧領域
101,102…送電装置
161…IDC検出部
162…伝送電力取得部
163…周波数制御部
164…記憶部
165…制御部
201…受電装置
221…直列共振回路
222…並列共振回路 C1 ... Capacitor C21, C22 ... Capacitor C3 ... Capacitor Cp ... Capacitor E11, E12 ... First input electrode E13 ... Internal electrode E21, E22 ... Second input electrode E23 ... Internal electrode E31, E32 ... First output electrode E33 ... Internal electrode E41, E42 ... second output electrode E43 ... internal electrodes E51, E52 ... third output electrode E53 ... internal electrode L1 ... leakage inductance L2 ... inductor Lp ... inductors Q1, Q2, Q3, Q4 ... switch elements R1, R2 ... resistance RL ... Load circuit Rp ... Resistance T1 ... Step-up transformer T2 ... Transformers 1 and 2 ... Power transmission system 11 ... DC power supply 12 ... Inverter circuits 13 and 23 ... Active electrodes 14 and 24 ... Passive electrodes 15 ... PWM control circuit 16 ... Control circuit 17 ... Parallel resonant circuit 18 ... Series resonant circuit 22 ... Piezoelectric transformer 25 ... Rectification flat Circuit 30 ... piezoelectric plate 31 ... first low voltage region 32 ... first high voltage region 33 ... second high voltage region 34 ... second low voltage region 35 ... third high voltage region 36 ... fourth high voltage region 37 ... Third low voltage region 101, 102 ... Power transmission device 161 ... IDC detection unit 162 ... Transmission power acquisition unit 163 ... Frequency control unit 164 ... Storage unit 165 ... Control unit 201 ... Power reception device 221 ... Series resonance circuit 222 ... Parallel resonance circuit
C21,C22…キャパシタ
C3…キャパシタ
Cp…キャパシタ
E11,E12…第1入力電極
E13…内部電極
E21,E22…第2入力電極
E23…内部電極
E31,E32…第1出力電極
E33…内部電極
E41,E42…第2出力電極
E43…内部電極
E51,E52…第3出力電極
E53…内部電極
L1…漏れインダクタンス
L2…インダクタ
Lp…インダクタ
Q1,Q2,Q3,Q4…スイッチ素子
R1,R2…抵抗
RL…負荷回路
Rp…抵抗
T1…昇圧トランス
T2…トランス
1,2…電力伝送システム
11…直流電源
12…インバータ回路
13,23…アクティブ電極
14,24…パッシブ電極
15…PWM制御回路
16…制御回路
17…並列共振回路
18…直列共振回路
22…圧電トランス
25…整流平滑回路
30…圧電体板
31…第1低電圧領域
32…第1高電圧領域
33…第2高電圧領域
34…第2低電圧領域
35…第3高電圧領域
36…第4高電圧領域
37…第3低電圧領域
101,102…送電装置
161…IDC検出部
162…伝送電力取得部
163…周波数制御部
164…記憶部
165…制御部
201…受電装置
221…直列共振回路
222…並列共振回路 C1 ... Capacitor C21, C22 ... Capacitor C3 ... Capacitor Cp ... Capacitor E11, E12 ... First input electrode E13 ... Internal electrode E21, E22 ... Second input electrode E23 ... Internal electrode E31, E32 ... First output electrode E33 ... Internal electrode E41, E42 ... second output electrode E43 ... internal electrodes E51, E52 ... third output electrode E53 ... internal electrode L1 ... leakage inductance L2 ... inductor Lp ... inductors Q1, Q2, Q3, Q4 ... switch elements R1, R2 ... resistance RL ... Load circuit Rp ... Resistance T1 ... Step-up transformer T2 ...
Claims (4)
- 送電装置の送電側第1電極及び送電側第2電極と、受電装置の受電側第1電極及び受電側第2電極とが、電界結合することで送電装置から受電装置へ電力を伝送する電力伝送システムにおいて、
前記送電装置は、
直流電源から出力された直流電圧を交流電圧に変換するインバータ回路と、
設定された駆動周波数で前記インバータ回路をPWM制御するPWM制御回路と、
前記インバータ回路から出力される交流電圧を昇圧し、前記送電側第1電極及び前記送電側第2電極へ印加する昇圧トランスと、
前記昇圧トランスと、前記送電側第1電極及び前記送電側第2電極との間に接続された、又は、前記昇圧トランスの一部と共に構成される、第1の共振回路と、
を備え、
前記受電装置は、
前記受電側第1電極及び前記受電側第2電極に誘起される電圧を降圧する圧電トランスと、
前記圧電トランスの等価回路の一部を含んで構成され、前記第1の共振回路と同じ共振周波数を有する第2の共振回路と、
を備え、
前記送電装置は、
前記駆動周波数を掃引すると共に、前記第1の共振回路及び前記第2の共振回路の共振周波数を検出する共振周波数検出部と、
所定周期で、前記共振周波数検出部が検出した共振周波数を前記駆動周波数に設定する駆動周波数設定部と、
を備えた、
電力伝送システム。 Power transmission for transmitting power from the power transmitting device to the power receiving device by electric field coupling between the power transmitting side first electrode and the power transmitting side second electrode of the power transmitting device and the power receiving side first electrode and the power receiving side second electrode of the power receiving device. In the system,
The power transmission device is:
An inverter circuit for converting a DC voltage output from a DC power source into an AC voltage;
A PWM control circuit for PWM controlling the inverter circuit at a set drive frequency;
A step-up transformer that boosts an alternating voltage output from the inverter circuit and applies the boosted voltage to the power transmission side first electrode and the power transmission side second electrode;
A first resonance circuit connected between the step-up transformer and the power transmission side first electrode and the power transmission side second electrode, or configured together with a part of the step-up transformer;
With
The power receiving device is:
A piezoelectric transformer for stepping down a voltage induced in the power receiving side first electrode and the power receiving side second electrode;
A second resonance circuit including a part of an equivalent circuit of the piezoelectric transformer and having the same resonance frequency as the first resonance circuit;
With
The power transmission device is:
A resonance frequency detector that sweeps the drive frequency and detects a resonance frequency of the first resonance circuit and the second resonance circuit;
A drive frequency setting unit that sets the resonance frequency detected by the resonance frequency detection unit to the drive frequency at a predetermined period;
With
Power transmission system. - 前記駆動周波数設定部は、
異なるタイミングで前記共振周波数検出部が検出した共振周波数の変化量が小さくなるに伴い、前記所定周期を長くする、
請求項1に記載の電力伝送システム。 The drive frequency setting unit includes:
As the amount of change in the resonance frequency detected by the resonance frequency detector at a different timing becomes smaller, the predetermined period is lengthened.
The power transmission system according to claim 1. - 前記送電装置は、前記インバータ回路に流れる電流を検出する電流検出部を備え、
前記共振周波数検出部は、前記駆動周波数が掃引された時の、前記電流検出部により検出された電流値の周波数特性に基づいて、前記共振周波数を検出する、
請求項1又は2に記載の電力伝送システム。 The power transmission device includes a current detection unit that detects a current flowing through the inverter circuit,
The resonance frequency detection unit detects the resonance frequency based on frequency characteristics of a current value detected by the current detection unit when the drive frequency is swept.
The power transmission system according to claim 1 or 2. - 前記送電装置は、
前記受電装置へ伝送する伝送電力を検出する伝送電力検出部と、
伝送電力に応じた前記第1の共振回路及び前記第2の共振回路の共振周波数の検出条件を記憶する記憶部と、
を備え、
前記共振周波数検出部は、
前記伝送電力検出部が検出した伝送電力に応じた検出条件を前記記憶部から取得し、取得した検出条件と、前記駆動周波数を掃引したときに前記電流検出部が検出した電流値の周波数特性とに基づいて、共振周波数を検出する、
請求項3に記載の電力伝送システム。 The power transmission device is:
A transmission power detector that detects transmission power to be transmitted to the power receiving device;
A storage unit for storing a detection condition of a resonance frequency of the first resonance circuit and the second resonance circuit according to transmission power;
With
The resonance frequency detector is
The detection condition according to the transmission power detected by the transmission power detection unit is acquired from the storage unit, the acquired detection condition, and the frequency characteristic of the current value detected by the current detection unit when the drive frequency is swept To detect the resonant frequency based on
The power transmission system according to claim 3.
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107453492A (en) * | 2016-05-30 | 2017-12-08 | 三星电机株式会社 | Resonance modules and the wireless power transmitter including the resonance modules |
CN107710550A (en) * | 2016-02-05 | 2018-02-16 | 广东欧珀移动通信有限公司 | For the charging system of terminal, charging method and power supply adaptor |
JP2019511182A (en) * | 2017-02-24 | 2019-04-18 | クワントン オーピーピーオー モバイル テレコミュニケーションズ コーポレイション リミテッド | Equalization circuit, device to be charged, and charge control method |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2012065410A (en) * | 2010-09-15 | 2012-03-29 | Ihi Corp | Power-saving driving device and method for device having same load pattern |
WO2013080647A1 (en) * | 2011-12-01 | 2013-06-06 | 株式会社村田製作所 | Step-down circuit and incoming device using step-down circuit |
JP2013529048A (en) * | 2011-05-13 | 2013-07-11 | 株式会社村田製作所 | POWER TRANSMISSION DEVICE, POWER RECEIVING DEVICE, AND POWER TRANSMISSION SYSTEM |
JP2013243788A (en) * | 2012-05-17 | 2013-12-05 | Tokyo Keiki Inc | Electric-field-coupled contactless power transmission system |
-
2015
- 2015-01-21 WO PCT/JP2015/051477 patent/WO2015125539A1/en active Application Filing
- 2015-01-21 JP JP2016504006A patent/JP6132066B2/en active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2012065410A (en) * | 2010-09-15 | 2012-03-29 | Ihi Corp | Power-saving driving device and method for device having same load pattern |
JP2013529048A (en) * | 2011-05-13 | 2013-07-11 | 株式会社村田製作所 | POWER TRANSMISSION DEVICE, POWER RECEIVING DEVICE, AND POWER TRANSMISSION SYSTEM |
WO2013080647A1 (en) * | 2011-12-01 | 2013-06-06 | 株式会社村田製作所 | Step-down circuit and incoming device using step-down circuit |
JP2013243788A (en) * | 2012-05-17 | 2013-12-05 | Tokyo Keiki Inc | Electric-field-coupled contactless power transmission system |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107710550A (en) * | 2016-02-05 | 2018-02-16 | 广东欧珀移动通信有限公司 | For the charging system of terminal, charging method and power supply adaptor |
CN107453492A (en) * | 2016-05-30 | 2017-12-08 | 三星电机株式会社 | Resonance modules and the wireless power transmitter including the resonance modules |
JP2019511182A (en) * | 2017-02-24 | 2019-04-18 | クワントン オーピーピーオー モバイル テレコミュニケーションズ コーポレイション リミテッド | Equalization circuit, device to be charged, and charge control method |
EP3561990A4 (en) * | 2017-02-24 | 2020-01-01 | Guangdong Oppo Mobile Telecommunications Corp., Ltd. | Equalisation circuit, device to be charged, and charging control method |
US10541541B2 (en) | 2017-02-24 | 2020-01-21 | Guangdong Oppo Mobile Telecommunications Corp., Ltd. | Equalization circuit, device to be charged and charging control method |
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