CN109039214B - Method and system for adjusting direct current bus voltage - Google Patents
Method and system for adjusting direct current bus voltage Download PDFInfo
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- CN109039214B CN109039214B CN201810895275.4A CN201810895275A CN109039214B CN 109039214 B CN109039214 B CN 109039214B CN 201810895275 A CN201810895275 A CN 201810895275A CN 109039214 B CN109039214 B CN 109039214B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2201/00—Indexing scheme relating to controlling arrangements characterised by the converter used
- H02P2201/09—Boost converter, i.e. DC-DC step up converter increasing the voltage between the supply and the inverter driving the motor
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Abstract
The invention provides a method and a system for adjusting direct current bus voltage, comprising the following steps: the power converter, the capacitor, the inverter, the motor, the detector and the drive controller; outputting a direct current bus voltage based on an alternating current input voltage, wherein the variation trend of the average value of the direct current bus voltage follows the variation trend of the effective value of the alternating current input voltage; and adjusting the direct current bus voltage according to the actual power of the motor, so that the waveforms of the absolute values of the direct current bus voltage and the alternating current input voltage are not overlapped. The invention reduces the device cost and the production cost and simultaneously improves the conversion efficiency of the motor under light load under the condition of ensuring that the total harmonic distortion rate of the alternating current input voltage meets the standard.
Description
Technical Field
The invention relates to the field of frequency conversion, in particular to a method and a system for adjusting direct-current bus voltage.
Background
The variable frequency driving system realizes speed regulation by changing the power supply frequency of the motor, thereby regulating the load, reducing power consumption, reducing loss and prolonging the service life of equipment.
In the existing variable frequency driving system, in order to output a stable dc bus voltage, a smoothing capacitor with a large capacitance value is generally arranged at the rear end of a Power converter (also called a Power Factor Corrector (PFC), the diameter and the height of the smoothing capacitor are both large, the smoothing capacitor needs to occupy a large plane position and a large space position when arranged on a circuit board, and the cost is high; if an electrolytic capacitor with a small capacitance value and a low cost is used, the ripple voltage Δ V of the dc bus is causedoBecomes larger, as shown in FIG. 1, once the DC bus voltage V is appliedoLower than the absolute value V of the AC input voltageiDistortion of the input current is caused, which affects the Total Harmonic Distortion (THD) of the input power.
Therefore, how to reduce the cost and improve the efficiency while ensuring that the total harmonic distortion rate of the system meets the standard has become one of the problems to be solved urgently by those skilled in the art.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a method and a system for adjusting a dc bus voltage, which are used to solve the problems of large size and high cost of a smoothing capacitor for stabilizing the dc bus voltage in the prior art.
To achieve the above and other related objects, the present invention provides a method for adjusting a dc bus voltage, the method at least comprising:
1) outputting a direct current bus voltage based on an alternating current input voltage, wherein the variation trend of the average value of the direct current bus voltage follows the variation trend of the effective value of the alternating current input voltage;
2) and adjusting the direct current bus voltage according to the actual power of the motor, so that the waveforms of the absolute values of the direct current bus voltage and the alternating current input voltage are not overlapped.
Preferably, step 2) further comprises: and the minimum value of the difference value of the absolute value of the direct current bus voltage corresponding to each sampling point and the absolute value of the alternating current input voltage in one sampling period is not more than a set value.
More preferably, in step 2), adjusting the dc bus voltage according to the actual power of the motor includes: increasing the DC bus voltage as the actual power increases; reducing the DC bus voltage as the actual power decreases.
Preferably, step 1) comprises:
11) calculating to obtain a direct current bus set voltage based on the alternating current input voltage effective value and the direct current bus ripple voltage;
12) and performing closed-loop control based on the direct-current bus set voltage and the direct-current bus voltage so as to enable the average value of the direct-current bus voltage to follow the direct-current bus set voltage.
More preferably, step 2) comprises:
21) adjusting the set voltage of the direct current bus according to the actual power of the motor;
22) and performing closed-loop control based on the direct-current bus set voltage and the direct-current bus voltage so as to enable the average value of the direct-current bus voltage to follow the direct-current bus set voltage.
More preferably, the closed-loop control comprises:
calculating the duty ratio of a power switch tube in the power converter based on the set voltage of the direct-current bus and the voltage of the direct-current bus;
and controlling a power switch tube in the power converter to be switched on or switched off according to the calculated duty ratio so as to enable the average value of the voltage of the direct current bus to follow the value of the set voltage of the direct current bus.
To achieve the above and other related objects, the present invention provides a system for regulating dc bus voltage, comprising:
the power converter receives an alternating current input voltage and is used for converting the alternating current input voltage into a direct current bus voltage;
the capacitor is connected to the output end of the power converter and used for stabilizing the direct current bus voltage;
the inverter is connected with the capacitor and is used for converting the direct current bus voltage into alternating current output voltage;
the motor is connected to the output end of the inverter and is driven by the alternating-current output voltage to operate;
a detector connected to the power converter, the capacitor and the motor, for detecting the ac input voltage, the dc bus voltage, an actual voltage and an actual current of the motor;
the driving controller is connected to the output end of the detector and controls the power converter to output the direct-current bus voltage according to the alternating-current input voltage, so that the variation trend of the average value of the direct-current bus voltage follows the variation trend of the effective value of the alternating-current input voltage; and controlling the power converter to adjust the DC bus voltage according to the actual power of the motor, so that the waveforms of the absolute values of the DC bus voltage and the AC input voltage are not overlapped.
Preferably, the output end of the driving controller is further connected to the inverter for adjusting the ac output voltage and the rotation speed of the motor.
Preferably, the power converter is a boost circuit.
Preferably, the power converter comprises a rectifying unit, an inductor, a first power switch tube and a diode; the input end of the rectifying unit is respectively connected with a live wire and a zero line of the alternating-current input voltage; one end of the inductor is connected with the anode of the output end of the rectifying unit, and the other end of the inductor is connected with the first end of the first power switch tube; the second end of the first power switch tube is connected with the negative electrode of the output end of the rectifying unit, and the third end of the first power switch tube is connected with the driving controller; the anode of the diode is connected with the drain electrode of the first power switch tube, and the cathode of the diode is connected with the upper polar plate of the capacitor.
Preferably, the inverter includes six power switching tubes, wherein a second power switching tube and a third power switching tube are connected in series to two ends of the capacitor, a fourth power switching tube and a fifth power switching tube are connected in series to two ends of the capacitor, a sixth power switching tube and a seventh power switching tube are connected in series to two ends of the capacitor, and control ends of the power switching tubes are respectively connected to the driving controller.
As described above, the method and system for adjusting the dc bus voltage of the present invention have the following advantages:
the method adjusts the direct current bus voltage in real time according to the effective value of the alternating current input voltage and the change of the motor power, on one hand, the direct current bus voltage is ensured to be higher than the absolute value of the alternating current input voltage at any moment, and therefore the total harmonic distortion rate of the alternating current input voltage is ensured to meet the standard; on the other hand, the average value of the direct current bus voltage is close to the peak value of the alternating current input voltage, so that the loss of the power converter is effectively reduced, and the conversion efficiency of the motor under light load is improved.
The method and the system for adjusting the direct current bus voltage can reduce the capacitance value of a capacitor for stabilizing the direct current bus voltage, reduce the plane size and the space size of a circuit board, and further effectively reduce the device cost and the production cost.
Drawings
Fig. 1 shows a schematic diagram of the principle of the prior art for causing distortion of input current.
Fig. 2 is a schematic diagram of a system for regulating dc bus voltage according to the present invention.
Fig. 3 and 4 are schematic diagrams illustrating a method for adjusting a dc bus voltage according to the present invention.
Fig. 5 is a schematic diagram of the power converter, the capacitor, the inverter and the motor according to the present invention.
Description of the element reference numerals
1 power converter
11 rectifying unit
2 inverter
3 electric machine
4 detector
5 drive controller
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 2 to 5. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The present invention provides a method for adjusting a dc bus voltage, in this embodiment, the method for adjusting a dc bus voltage is implemented based on a system for adjusting a dc bus voltage as shown in fig. 2, where the system for adjusting a dc bus voltage includes: a power converter 1, a capacitor C1, an inverter 2, a motor 3, a detector 4, and a drive controller 5. The method for adjusting the direct current bus voltage comprises the following steps:
1) and outputting the direct current bus voltage Vo based on the alternating current input voltage Vac, wherein the variation trend of the average value of the direct current bus voltage Vo follows the variation trend of the effective value of the alternating current input voltage.
Specifically, in the present embodiment, a boost following method is adopted, as shown in fig. 3 and 4, the average value of the dc bus voltage Vo is greater than the absolute value Vi of the ac input voltage, and the average value of the dc bus voltage Vo gradually increases as the effective value of the ac input voltage increases. Further comprising the steps of:
11) and calculating to obtain the set voltage of the direct current bus based on the effective value of the alternating current input voltage and the ripple voltage of the direct current bus.
Specifically, the ac input voltage Vac or the output terminal of the rectifying unit 11 is detected to obtain the absolute value Vi of the ac input voltage. Calculating the setting voltage Vref of the dc bus based on the effective value of the ac input voltage, where in this embodiment, the setting voltage Vref of the dc bus satisfies the following relationship:
wherein Vref is the set voltage of the DC bus, VeffIs an effective value of the alternating current input voltage,
is the peak value, Δ V, of the absolute value Vi of the AC input voltageoThe direct current bus ripple voltage is obtained.
12) And performing closed-loop control on the basis of the direct current bus set voltage Vref and the direct current bus voltage Vo so as to enable the average value of the direct current bus voltage Vo to follow the direct current bus set voltage Vref.
The closed-loop control further comprises the steps of:
121) and calculating the duty ratio of a power switch tube in the power converter based on the direct current bus set voltage Vref and the direct current bus voltage Vo.
Specifically, the capacitor C1 is detected to obtain the dc bus voltage Vo; the dc bus voltage Vref is set as a target value, the dc bus voltage Vo is an actual output value, and the duty ratio of the first power switch Q1 in the power converter 1 is set based on the difference between the actual output value and the target value.
122) And controlling a first power switch tube Q1 in the power converter 1 to be switched on or switched off at the calculated duty ratio so as to enable the average value of the direct current bus voltage Vo to follow the direct current bus set voltage Vref.
Specifically, in the present embodiment, the calculated duty ratio is applied to the gate of the first power switch Q1 through the first control signal Ctl1, and the output voltage of the power converter 1 is adjusted through the duty ratio variation of the first control signal Ctl 1. The average value of the direct current bus voltage Vo is equal to the direct current bus set voltage Vref, or the difference value of the direct current bus voltage Vo and the direct current bus set voltage Vref is within a set range.
Then, the on/off of each power switching tube (Q21 to Q26) in the inverter 2 is controlled based on the built-in set rotational speed, thereby controlling the rotational speed and voltage of the motor 3.
2) And adjusting the set voltage Vref of the direct current bus according to the actual power Po of the motor 3 to ensure that the waveforms of the direct current bus voltage Vo and the absolute value Vi of the alternating current input voltage are not overlapped. Further comprising the steps of:
21) and adjusting the set voltage Vref of the direct current bus according to the actual power Po of the motor 3.
Specifically, the actual voltage and the actual current of the motor 3 are detected to obtain the actual power Po (product of the actual voltage and the actual current) of the motor 3.
Specifically, as the actual power Po increases, the dc bus set voltage Vref is increased so that the waveforms of the dc bus voltage Vo and the ac input voltage absolute value Vi do not overlap; meanwhile, under the condition that the waveforms of the direct current bus voltage Vo and the alternating current input voltage absolute value Vi are not overlapped, the average value of the direct current bus voltage Vo and the peak value of the alternating current input voltage absolute value Vi are enabled to be as close as possible, namely the direct current bus voltage Vo and the alternating current input voltage absolute value Vi are sampled at each moment in a sampling period, two values obtained at the same moment correspond to a difference value, and the minimum value of the difference values corresponding to each sampling moment in the sampling period is not larger than a set value, so that high conversion efficiency is achieved.
Specifically, with the decrease of the actual power Po, the dc bus set voltage Vref is decreased, so that the waveforms of the dc bus voltage Vo and the ac input voltage absolute value Vi are not overlapped, and meanwhile, under the condition that the waveforms of the dc bus voltage Vo and the ac input voltage absolute value Vi are not overlapped, the average value of the dc bus voltage Vo and the peak value of the ac input voltage absolute value Vi are made to be as close as possible, that is, the minimum value of the difference value between the dc bus voltage Vo and the ac input voltage absolute value Vi corresponding to each sampling point in one sampling period is not greater than a set value, so as to achieve high conversion efficiency.
It should be noted that the set value can be obtained by calculation according to specific system parameters and required conversion efficiency, and is not limited to a specific value, and in this embodiment, the set value is 15V. In addition, in this embodiment, a minimum value of a difference value between the dc bus voltage Vo and the ac input voltage absolute value Vi corresponding to each sampling point in a sampling period is not less than a safety value, so as to ensure that there is no risk of overlapping waveforms of the dc bus voltage Vo and the ac input voltage absolute value Vi, where the safety value may be obtained according to specific system parameters, and in this embodiment, the safety value is 5V. Preferably, the minimum value of the difference between the dc bus voltage Vo and the absolute value Vi of the ac input voltage corresponding to each sampling point in a sampling period is set to 10V, so as to ensure the conversion efficiency of the motor 3 on the basis that the total harmonic distortion of the ac input voltage meets the standard.
22) And performing closed-loop control based on the direct-current bus set voltage and the direct-current bus voltage so as to enable the average value of the direct-current bus voltage to follow the direct-current bus set voltage. The method for adjusting the voltage of the direct current bus by closed-loop control is the same as that in the step 1), and is not repeated here.
As shown in FIGS. 3 and 4, according to the formula C1 ≧ Po/(2πf·1/2ΔVo·Vo) When light load (the actual power Po is small)The ripple voltage Δ V of the DC buso(Note as. DELTA.V)o1) Is small; at this time, the dc bus set voltage Vref is appropriately decreased to a mean value (denoted as V) of the dc bus voltage Voo1') and the waveform of the absolute value Vi of the alternating current input voltage are not overlapped (namely the direct current bus voltage Vo at any time is larger than the absolute value Vi of the alternating current input voltage), and the average value (marked as V) of the direct current bus voltage Vo is enabled to beo1') is close to the peak value of the absolute value Vi of the ac input voltage, so that the loss of the power converter 1 can be reduced and the conversion efficiency of the motor 3 under light load can be improved.
As shown in FIGS. 3 and 4, according to the formula C1 ≧ Po/(2πf·1/2ΔVo·Vo) When the load is heavy (the actual power Po is larger), the ripple voltage DeltaV of the direct current buso(Note as. DELTA.V)o2) Is large; at this time, the dc bus voltage Vo is averaged (denoted as V) by increasing the dc bus set voltage Vref as appropriateo2') is not overlapped with the waveform of the absolute value Vi of the alternating-current input voltage (namely, the direct-current bus voltage Vo at any moment is larger than the absolute value Vi of the alternating-current input voltage); meanwhile, on the premise of ensuring that the waveform of the average value of the direct current bus voltage Vo and the waveform of the absolute value Vi of the alternating current input voltage do not overlap, the average value (denoted as V) of the direct current bus voltage Voo2') approaches the peak value of the absolute value Vi of the ac input voltage, thereby ensuring the conversion efficiency of the motor 3 on the basis that the total harmonic distortion of the ac input voltage meets the standard.
As shown in fig. 2, in this embodiment, the system for adjusting the dc bus voltage includes:
a power converter 1, a capacitor C1, an inverter 2, a motor 3, a detector 4, and a drive controller 5.
As shown in fig. 2, the power converter 1 receives an ac input voltage Vac, and is configured to convert the ac input voltage Vac into a dc bus voltage Vo.
Specifically, the power converter 1 is a boost circuit, a buck circuit or a buck-boost circuit, and different power converter structures can be set as needed, which is not limited to this embodiment. As shown in fig. 5, in the present embodiment, the power converter 1 includes one of a rectifying unit 11 and a boost circuit, where the boost circuit includes an inductor L, a first power switch Q1, and a diode D.
More specifically, the input end of the rectifying unit 11 is connected to the live line L and the neutral line N of the ac input voltage Vac, the rectifying unit 11 includes four diodes and a filter capacitor C2, the four diodes form a rectifier bridge structure, and the filter capacitor C2 is connected between the output ends of the rectifier bridge. One end of the inductor L is connected to the positive electrode of the output end of the rectifying unit 11, and the other end of the inductor L is connected to the drain of the first power switch Q1. The source of the first power switch Q1 is connected to the negative electrode of the output end of the rectifying unit 11, the gate is connected to a first control signal Ctl1, and the first control signal Ctl1 controls the on and off of the first power switch Q1, so as to control the magnitude of the dc bus voltage output by the power converter 1, in this embodiment, the first power switch Q1 is a metal-oxide semiconductor field effect transistor; in practical applications, the type of the first power switch Q1 may be set as required, including but not limited to an igbt, where the collector of the first power switch Q1 is connected to the inductor L, the emitter of the first power switch Q1 is connected to the negative terminal of the output terminal of the rectifying unit 11, and the gate of the first power switch Q1 is connected to the first control signal Ctl 1. The positive electrode of the diode D is connected to the drain of the first power switch Q1, and the diode D is used to prevent the capacitor C1 from discharging to the negative DC-BUS-of the DC BUS voltage Vo. The cathode of the diode D is the anode DC-BUS + of the DC BUS voltage Vo, and the source of the first power switch Q1 is the cathode DC-BUS-of the DC BUS voltage Vo.
As shown in fig. 2, the capacitor C1 is connected to the output terminal of the power converter 1 for stabilizing the dc bus voltage Vo.
Specifically, as shown in fig. 5, the upper plate of the capacitor C1 is connected to the positive DC-BUS of the DC BUS voltage Vo, and the lower plate is connected to the negative DC-BUS of the DC BUS voltage Vo.
As shown in fig. 2, the inverter 2 is connected to the capacitor C1 for converting the dc bus voltage Vo into an ac output voltage.
Specifically, the structure of the inverter 2 may be any one selected as needed, and is not limited to this embodiment. As shown in fig. 5, in the present embodiment, the inverter 2 includes six power switching tubes to form a three-phase inverter bridge, wherein the second power switching tube Q21 and the third power switching tube Q22 are connected in series between the positive DC-BUS + of the DC BUS voltage Vo and the negative DC-BUS-of the DC BUS voltage Vo; the fourth power switch tube Q23 and the fifth power switch tube Q24 are connected in series between the positive pole DC-BUS + of the direct current BUS voltage Vo and the negative pole DC-BUS-of the direct current BUS voltage Vo; the sixth power switch tube Q25 and the seventh power switch tube Q26 are connected in series between the positive pole DC-BUS + of the direct current BUS voltage Vo and the negative pole DC-BUS-of the direct current BUS voltage Vo; in the present embodiment, the control signals of the power switches (Q21-Q26) are a set of control bus Ctl2[5:0], and the control bus includes 6 bits. In this embodiment, each power switch tube in the inverter 2 is an insulated gate bipolar transistor, and the type of each power switch tube may be set as required in actual use. And the three-phase output end of the inverter circuit 2 is connected with the three-phase input end of the motor 3.
As shown in fig. 2, the motor 3 is connected to an output end of the inverter 2 and is driven by the ac output voltage.
Specifically, as shown in fig. 5, in the present embodiment, the motor 3 is a three-phase motor, and when the three-phase stator windings (each having an electrical angle difference of 120 degrees) of the motor are supplied with the ac output voltage, a rotating magnetic field is generated, and the rotating magnetic field cuts the rotor windings, so as to generate an induced current in the rotor windings.
It should be noted that, in actual use, the motor 3 may be a single-phase motor, and the structure of the inverter 2 is modified adaptively, which is not described herein.
As shown in fig. 2, the detector 4 is connected to the power converter 1, the capacitor C1, and the motor 3, and is configured to detect and obtain the ac input voltage Vac, the dc bus voltage Vo, and an actual voltage and an actual current of the motor 3.
Specifically, the detector 4 is connected to the power converter 1, and acquires the ac input voltage Vac or the ac input voltage absolute value Vi (the output signal of the rectifying unit). The detector 4 is connected to the capacitor C1 to obtain the voltage value of the capacitor C1, i.e. the dc bus voltage Vo (actual output value). The detector 4 is connected with the motor 3 to obtain the actual voltage and the actual current of the motor 3.
As shown in fig. 2, the driving controller 5 is connected to the output end of the detector 4, and controls the power converter 1 to output the dc bus voltage Vo according to the ac input voltage Vac, so that a variation trend of an average value of the dc bus voltage Vo follows a variation trend of the effective value of the ac input voltage; and then controlling the power converter 1 to adjust the direct current bus voltage Vo according to the actual power Po of the motor 3, so that the waveforms of the direct current bus voltage Vo and the absolute value Vi of the alternating current input voltage are not overlapped.
Specifically, the drive controller 5 calculates the dc bus set voltage Vref based on the ac input voltage effective value. The drive controller 5 calculates the duty ratio of the first control signal Ctl1 based on the dc bus set voltage Vref and the average value of the dc bus voltage Vo, and then realizes that the average value of the dc bus voltage Vo tracks the dc bus set voltage Vref through closed-loop control; meanwhile, the drive controller 5 calculates actual power Po of the motor 3 based on actual voltage and actual current of the motor 3, and the drive controller 5 calculates duty ratios of signals in the control bus Ctl2[5:0] based on the actual power Po and built-in set power, so as to realize that the motor 3 operates at a set rotating speed.
It should be noted that the input terminal of the power converter 1 may be further connected to a first common mode filter (not shown) as required, and the input terminal of the motor 3 may be further connected to a second common mode filter (not shown) as required, so as to reduce the common mode interference of the system for adjusting the dc bus voltage according to the present invention.
To sum up, the present invention provides a method and a system for adjusting a dc bus voltage, including: the power converter, the capacitor, the inverter, the motor, the detector and the drive controller; outputting a direct current bus voltage based on an alternating current input voltage, wherein the variation trend of the average value of the direct current bus voltage follows the variation trend of the effective value of the alternating current input voltage; and adjusting the direct current bus voltage according to the actual power of the motor, so that the waveforms of the absolute values of the direct current bus voltage and the alternating current input voltage are not overlapped. The method adjusts the direct current bus voltage in real time according to the effective value of the alternating current input voltage and the change of the motor power, on one hand, the direct current bus voltage is ensured to be higher than the absolute value of the alternating current input voltage at any moment, and therefore the total harmonic distortion rate of the alternating current input voltage is ensured to meet the standard; on the other hand, the average value of the direct current bus voltage is close to the peak value of the alternating current input voltage, so that the loss of the power converter is effectively reduced, and the conversion efficiency of the motor under light load is improved. The method and the system for adjusting the direct current bus voltage can reduce the capacitance value of a capacitor for stabilizing the direct current bus voltage, reduce the plane size and the space size of a circuit board, and further effectively reduce the device cost and the production cost. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (11)
1. A method of regulating a dc bus voltage, the method comprising:
1) outputting a direct current bus voltage based on an alternating current input voltage, wherein the variation trend of the average value of the direct current bus voltage follows the variation trend of the effective value of the alternating current input voltage;
2) and adjusting the direct current bus voltage according to the actual power of the motor, so that the waveforms of the absolute values of the direct current bus voltage and the alternating current input voltage are not overlapped.
2. The method of claim 1, wherein the method further comprises: step 2) further comprises: and the minimum value of the difference value of the absolute value of the direct current bus voltage corresponding to each sampling point and the absolute value of the alternating current input voltage in one sampling period is not more than a set value.
3. Method of regulating a dc bus voltage according to claim 1 or 2, characterized in that: in step 2), adjusting the dc bus voltage according to the actual power of the motor includes: increasing the DC bus voltage as the actual power increases; reducing the DC bus voltage as the actual power decreases.
4. The method of claim 1, wherein the method further comprises: the step 1) comprises the following steps:
11) calculating to obtain a direct current bus set voltage based on the alternating current input voltage effective value and the direct current bus ripple voltage;
12) and performing closed-loop control based on the direct-current bus set voltage and the direct-current bus voltage so as to enable the average value of the direct-current bus voltage to follow the direct-current bus set voltage.
5. The method of claim 4, wherein the method further comprises: the step 2) comprises the following steps:
21) adjusting the set voltage of the direct current bus according to the actual power of the motor;
22) and performing closed-loop control based on the direct-current bus set voltage and the direct-current bus voltage so as to enable the average value of the direct-current bus voltage to follow the direct-current bus set voltage.
6. The method of adjusting a dc bus voltage of claim 4 or 5, wherein: the closed-loop control includes:
calculating the duty ratio of a power switch tube in the power converter based on the set voltage of the direct-current bus and the voltage of the direct-current bus;
and controlling a power switch tube in the power converter to be switched on or switched off according to the calculated duty ratio so as to enable the average value of the voltage of the direct current bus to follow the value of the set voltage of the direct current bus.
7. A system for regulating a dc bus voltage, the system comprising:
the power converter receives an alternating current input voltage and is used for converting the alternating current input voltage into a direct current bus voltage;
the capacitor is connected to the output end of the power converter and used for stabilizing the direct current bus voltage;
the inverter is connected with the capacitor and is used for converting the direct current bus voltage into alternating current output voltage;
the motor is connected to the output end of the inverter and is driven by the alternating-current output voltage to operate;
a detector connected to the power converter, the capacitor and the motor, for detecting the ac input voltage, the dc bus voltage, an actual voltage and an actual current of the motor;
the driving controller is connected to the output end of the detector and controls the power converter to output the direct-current bus voltage according to the alternating-current input voltage, so that the variation trend of the average value of the direct-current bus voltage follows the variation trend of the effective value of the alternating-current input voltage; and controlling the power converter to adjust the DC bus voltage according to the actual power of the motor, so that the waveforms of the absolute values of the DC bus voltage and the AC input voltage are not overlapped.
8. The system for regulating dc bus voltage of claim 7, wherein: the output end of the driving controller is also connected with the inverter and is used for adjusting the alternating current output voltage and the rotating speed of the motor.
9. The system for regulating dc bus voltage of claim 7, wherein: the power converter includes a boost circuit.
10. The system for regulating dc bus voltage of claim 7, wherein: the power converter comprises a rectifying unit, an inductor, a first power switch tube and a diode; the input end of the rectifying unit is respectively connected with a live wire and a zero line of the alternating-current input voltage; one end of the inductor is connected with the anode of the output end of the rectifying unit, and the other end of the inductor is connected with the first end of the first power switch tube; the second end of the first power switch tube is connected with the negative electrode of the output end of the rectifying unit, and the third end of the first power switch tube is connected with the driving controller; the anode of the diode is connected with the drain electrode of the first power switch tube, and the cathode of the diode is connected with the upper polar plate of the capacitor.
11. The system for regulating dc bus voltage of claim 7, wherein: the inverter comprises six power switch tubes, wherein a second power switch tube and a third power switch tube are connected in series at two ends of the capacitor, a fourth power switch tube and a fifth power switch tube are connected in series at two ends of the capacitor, a sixth power switch tube and a seventh power switch tube are connected in series at two ends of the capacitor, and control ends of the power switch tubes are respectively connected with the driving controller.
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| CN117543674A (en) * | 2020-07-21 | 2024-02-09 | 华为技术有限公司 | Voltage control method and device for direct current bus and power system |
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| CN101383513A (en) * | 2008-10-23 | 2009-03-11 | 上海儒竞电子科技有限公司 | Single-phase power factor correcting single cycle controller |
| CN202889188U (en) * | 2012-09-28 | 2013-04-17 | 广东美的制冷设备有限公司 | Following-type active PFC control circuit |
| CN204615631U (en) * | 2015-02-04 | 2015-09-02 | 上海科世达-华阳汽车电器有限公司 | A kind of busbar voltage ripple compensation control circuit of circuit of power factor correction |
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