Power conversion device, motor drive device, and refrigeration cycle application device

Abstract

The power conversion device (1) includes: a rectifying section (130) that rectifies first AC power supplied from a commercial power source (110); a capacitor (210) connected to output terminals of the rectifying section (130); an inverter (310) connected to both ends of the capacitor (210), which converts power output from the rectifying section (130) and the capacitor (210) into second AC power and outputs the second AC power to a load having a motor (314); and a control section (400) that controls operation of the inverter (310) so that the second AC power containing a ripple corresponding to a ripple of power flowing into the capacitor (210) from the rectifying section (130) is output from the inverter (310) to the load, and a current flowing to the capacitor (210) is suppressed.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power conversion device that converts alternating-current power into desired power, a motor drive device, and a refrigeration cycle application apparatus. BACKGROUND

[0002] Conventionally, there is a power conversion device that converts alternating-current power supplied from an alternating-current power source into desired alternating-current power and supplies it to a load such as an air conditioner. For example, in Patent Literature 1, a technology is disclosed in which a power conversion device that is a control device of an air conditioner rectifies alternating-current power supplied from an alternating-current power source using a diode stack as a rectification section, further converts the power smoothed by a smoothing capacitor into desired alternating-current power using an inverter composed of a plurality of switching elements, and outputs it to a compressor motor that is a load.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. H7-71805 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, according to the above-described related art, a large current flows to the smoothing capacitor, and thus there is a problem that the degradation of the smoothing capacitor is accelerated over the years. As a measure against such a problem, a method of increasing the capacitance of the smoothing capacitor to suppress the ripple change of the capacitor voltage or using a smoothing capacitor that has a large tolerance to degradation caused by ripple is considered, but the cost of the capacitor component becomes high, and the device becomes large.

[0008] The present disclosure was completed in view of the above-described circumstances, and aims to obtain a power conversion device that can suppress the degradation of a capacitor for smoothing and suppress the large size of a device.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] In order to solve the above-described problems and achieve the aim, the power conversion device of the present disclosure includes a rectification section that rectifies first alternating-current power supplied from a commercial power source, a capacitor that is connected to an output terminal of the rectification section, an inverter that is connected to both ends of the capacitor, converts power output from the rectification section and the capacitor into second alternating-current power, and outputs it to a load having a motor, and a control section that controls the operation of the inverter so that the second alternating-current power containing a pulsation corresponding to a pulsation of power flowing into the capacitor from the rectification section is output from the inverter to the load, and the current flowing to the capacitor is suppressed.

[0011] EFFECTS OF THE INVENTION

[0012] The power conversion device of the present disclosure has an effect of suppressing deterioration of a smoothing capacitor and suppressing enlargement of the device. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a diagram showing a structure example of the power conversion device of Embodiment 1.

[0014] Figure 2 is a diagram showing an example of each current and a capacitor voltage of the capacitor of the smoothing section in a case where the smoothing section is used to smooth the current output from the rectifying section and fix the current flowing to the inverter as a comparative example.

[0015] Figure 3 is a diagram showing an example of each current and a capacitor voltage of the capacitor of the smoothing section at the time when the control section of the power conversion device of Embodiment 1 controls the operation of the inverter and reduces the current flowing to the smoothing section.

[0016] Figure 4 is a flowchart showing the operation of the control section provided in the power conversion device of Embodiment 1.

[0017] Figure 5 is a diagram showing an example of a hardware structure of the control section provided in the power conversion device of Embodiment 1.

[0018] Figure 6 is a diagram showing a structure example of the refrigeration cycle application device of Embodiment 2. DETAILED DESCRIPTION

[0019] Hereinafter, the power conversion device, the motor drive device, and the refrigeration cycle application device of the embodiments of the present disclosure will be described in detail based on the drawings.

[0020] Embodiment 1.

[0021] Figure 1 is a diagram showing a structure example of the power conversion device 1 of Embodiment 1. The power conversion device 1 is connected to a commercial power source 110 and a compressor 315. The power conversion device 1 converts a first alternating current power of a power source voltage Vs supplied from the commercial power source 110 into a second alternating current power having a desired amplitude and phase and supplies it to the compressor 315. The power conversion device 1 is provided with a voltage current detection section 501, a reactor 120, a rectifying section 130, a voltage detection section 502, a smoothing section 200, an inverter 310, current detection sections 313a, 313b, and a control section 400. In addition, a motor drive device 2 is configured by the power conversion device 1 and a motor 314 provided in the compressor 315.

[0022] The voltage-current detection section 501 detects the voltage value and the current value of the first alternating-current power of the power supply voltage Vs supplied from the commercial power supply 110, and outputs the detected voltage value and the current value to the control section 400. The reactor 120 is connected between the voltage-current detection section 501 and the rectification section 130. The rectification section 130 has a bridge circuit composed of rectification elements 131 to 134, rectifies and outputs the first alternating-current power of the power supply voltage Vs supplied from the commercial power supply 110. The rectification section 130 performs full-wave rectification. The voltage detection section 502 detects the voltage value of the power rectified by the rectification section 130, and outputs the detected voltage value to the control section 400. The smoothing section 200 is connected to the output terminal of the rectification section 130 via the voltage detection section 502. The smoothing section 200 has a capacitor 210 as a smoothing element, and smoothes the power rectified by the rectification section 130. The capacitor 210 is, for example, an electrolytic capacitor, a film capacitor, or the like. The capacitor 210 has a capacitance that smoothes the power rectified by the rectification section 130, and the voltage in the capacitor 210 by the smoothing is not a full-wave rectified waveform shape of the commercial power supply 110, but a waveform shape in which a voltage ripple corresponding to the frequency of the commercial power supply 110 is superimposed on a direct-current component, and does not pulsate greatly. The frequency of the voltage ripple is twice the component of the frequency of the power supply voltage Vs in the case where the commercial power supply 110 is single-phase, and six times the component becomes the main component in the case where the commercial power supply 110 is three-phase. In the case where the power input from the commercial power supply 110 and the power output from the inverter 310 do not change, the amplitude of the voltage ripple is determined by the capacitance of the capacitor 210. For example, the voltage ripple generated in the capacitor 210 pulsates within a range in which the maximum value is less than twice the minimum value.

[0023] The inverter 310 is connected to both ends of the smoothing section 200, i.e., the capacitor 210. The inverter 310 has switching elements 311a to 311f and freewheeling diodes 312a to 312f. The inverter 310 converts the electric power output from the rectifying section 130 and the smoothing section 200 into the second AC electric power having a desired amplitude and phase and outputs the second AC electric power to the compressor 315 by turning on and off the switching elements 311a to 311f under the control of the control section 400. The current detecting sections 313a and 313b detect the current value of one phase of the three-phase electric currents output from the inverter 310 and output the detected current value to the control section 400. In addition, the control section 400 can calculate the current value of the remaining one phase output from the inverter 310 by acquiring the current values of two phases of the three-phase electric currents output from the inverter 310. The compressor 315 is a load having a motor 314 for driving the compressor. The motor 314 rotates in accordance with the amplitude and phase of the second AC electric power supplied from the inverter 310 and performs a compression operation. For example, in the case where the compressor 315 is a hermetic compressor for an air conditioner or the like, the load torque of the compressor 315 is mostly regarded as a constant torque load.

[0024] In addition, in the electric power conversion device 1, Figure 1 The configuration of each structure shown is an example, and the configuration of each structure is not limited to Figure 1 the example shown. For example, the reactor 120 can also be arranged at the rear stage of the rectifying section 130. In the following description, the voltage current detecting section 501, the voltage detecting section 502, and the current detecting sections 313a and 313b are sometimes collectively referred to as detecting sections. In addition, the voltage value and the current value detected by the voltage current detecting section 501, the voltage value detected by the voltage detecting section 502, and the current values detected by the current detecting sections 313a and 313b are sometimes referred to as detected values.

[0025] The control unit 400 obtains the voltage and current values ​​of the first AC power supply voltage Vs from the voltage and current detection unit 501, the voltage value of the power rectified by the rectifier unit 130 from the voltage detection unit 502, and the current value of the second AC power with the desired amplitude and phase converted by the inverter 310 from the current detection units 313a and 313b. The control unit 400 uses the detection values ​​detected by each detection unit to control the operation of the inverter 310, specifically the switching on and off of the switching elements 311a to 311f of the inverter 310. In this embodiment, the control unit 400 controls the operation of the inverter 310 so that the inverter 310 outputs a second AC power to the compressor 315, which is a load, such that the second AC power includes pulsations corresponding to the pulsations of the power flowing from the rectifier unit 130 to the capacitor 210 of the smoothing unit 200. The pulsation corresponding to the pulsation of the power flowing into the capacitor 210 of the smoothing section 200 is, for example, a pulsation that varies according to the frequency of the pulsation of the power flowing into the capacitor 210 of the smoothing section 200. Therefore, the control unit 400 suppresses the current flowing into the capacitor 210 of the smoothing section 200. Furthermore, the control unit 400 may not use all the detection values ​​obtained from each detection unit, or it may use only a portion of the detection values ​​for control.

[0026] Next, the operation of the control unit 400 provided in the power conversion device 1 will be explained. In this embodiment, in the power conversion device 1, the load generated by the inverter 310 and the compressor 315 can be regarded as a fixed load. The following explanation assumes that the smoothing unit 200 is connected to a constant current load when observing the current output from the smoothing unit 200. Here, as... Figure 1 As shown, let the current flowing from the rectifier section 130 be current I1, the current flowing to the inverter 310 be current I2, and the current flowing from the smoothing section 200 be current I3. Current I2 is the combined current of current I1 and current I3. Current I3 can be expressed as the difference between current I2 and current I1, i.e., current I2 - current I1. For current I3, let the discharge direction of the smoothing section 200 be the positive direction, and the charging direction of the smoothing section 200 be the negative direction. That is, sometimes the current flows into the smoothing section 200, and sometimes the current flows out of the smoothing section 200.

[0027] Figure 2This diagram illustrates, as a comparative example, an example of currents I1 to I3 and the capacitor voltage Vdc of capacitor 210 in the smoothing unit 200 when the current output from rectifier 130 is smoothed by smoothing unit 200 and the current I2 flowing to inverter 310 is fixed. From top to bottom, currents I1, I2, and I3, and the capacitor voltage Vdc of capacitor 210 corresponding to current I3 are shown. The vertical axis of currents I1, I2, and I3 represents the current value, and the vertical axis of capacitor voltage Vdc represents the voltage value. The horizontal axis represents time t. Furthermore, the carrier component of inverter 310 is actually superimposed on currents I2 and I3, but this is omitted here. The same applies thereafter. Figure 2 As shown, in the power conversion device 1, assuming that the current I1 flowing from the rectifier 130 is sufficiently smoothed by the smoothing unit 200, the current I2 flowing to the inverter 310 becomes a fixed current value. However, a large current I3 flows to the capacitor 210 of the smoothing unit 200, which becomes the main cause of degradation. Therefore, in this embodiment, in the power conversion device 1, the control unit 400 controls the current I2 flowing to the inverter 310, that is, controls the operation of the inverter 310, so as to reduce the current I3 flowing to the smoothing unit 200.

[0028] Figure 3 This diagram illustrates an example of how the control unit 400 of the power conversion device 1 in Embodiment 1 controls the operation of the inverter 310 to reduce the current I3 flowing to the smoothing section 200, specifically the currents I1 to I3 and the capacitor voltage Vdc of the capacitor 210 in the smoothing section 200. From top to bottom, the diagram shows the currents I1, I2, and I3, and the capacitor voltage Vdc of the capacitor 210 corresponding to the current I3. The vertical axis for currents I1, I2, and I3 represents the current value, and the vertical axis for capacitor voltage Vdc represents the voltage value. The horizontal axis represents time t. The control unit 400 of the power conversion device 1 controls the operation of the inverter 310, thereby reducing the currents I1 to I3 and the capacitor voltage Vdc of the smoothing section 200. Figure 3 The current I2 shown flows to inverter 310, thus, with Figure 2 Compared to the previous example, the frequency component of the current flowing from the rectifier section 130 into the smoothing section 200 can be reduced, thus reducing the current I3 flowing into the smoothing section 200. Specifically, the control section 400 controls the operation of the inverter 310 so that a current I2 containing a pulsating current with the frequency component of the current I1 as the main component flows into the inverter 310.

[0029] The frequency component of current I1 is determined by the frequency of the AC current supplied from commercial power supply 110 and the structure of rectifier 130. Therefore, control unit 400 can set the frequency component of the pulsating current overlapping with current I2 to a component with a predetermined amplitude and phase. The frequency component of the pulsating current overlapping with current I2 becomes a similar waveform to the frequency component of current I1. By bringing the frequency component of the pulsating current overlapping with current I2 closer to the frequency component of current I1, control unit 400 can reduce the current I3 flowing to smoothing unit 200 and reduce the pulsating voltage generated in capacitor voltage Vdc.

[0030] The control unit 400 controls the operation of the inverter 310 to ensure that the pulsation of the current flowing to the inverter 310 is the same as the pulsation of the second AC power output from the inverter 310 to the compressor 315. The control unit 400 controls the operation of the inverter 310 such that the pulsation in the second AC power output from the inverter 310 is less than the pulsation of the power output from the rectifier unit 130. The control unit 400 controls the amplitude and phase of the pulsation in the second AC power output from the inverter 310 such that the voltage ripple of the capacitor voltage Vdc, i.e., the voltage ripple generated in the capacitor 210, is less than the voltage ripple generated in the capacitor 210 when the second AC power output from the inverter 310 does not contain pulsations corresponding to the pulsation of the power flowing into the capacitor 210. Alternatively, the control unit 400 controls the amplitude and phase of the pulsations contained in the second AC power output from the inverter 310, such that the current ripple flowing into and out of the capacitor 210 is smaller than the current ripple generated in the capacitor 210 when the second AC power output from the inverter 310 does not contain pulsations corresponding to the pulsations flowing into the capacitor 210. When the second AC power output from the inverter 310 does not contain pulsations corresponding to the pulsations flowing into the capacitor 210, it means... Figure 2 The controls shown.

[0031] Furthermore, the AC current supplied from the commercial power supply 110 is not particularly limited; it can be single-phase or three-phase. The control unit 400 determines the frequency component of the pulsating current overlapping with the current I2 based on the first AC power supplied from the commercial power supply 110. Specifically, when the first AC power supplied from the commercial power supply 110 is single-phase, the control unit 400 controls the pulsating waveform of the current I2 flowing to the inverter 310 to be a shape obtained by adding a DC component to a pulsating waveform whose main component is a frequency component that is twice the frequency of the first AC power. Alternatively, when the first AC power supplied from the commercial power supply 110 is three-phase, the control unit 400 controls the pulsating waveform of the current I2 flowing to the inverter 310 to be a shape obtained by adding a DC component to a pulsating waveform whose main component is a frequency component that is six times the frequency of the first AC power. The pulsating waveform can be, for example, the shape of the absolute value of a sine wave or the shape of a sine wave. In this case, the control unit 400 may also add at least one frequency component of the sine wave whose frequency is an integer multiple of the sine wave to the pulsating waveform with a predetermined amplitude. Furthermore, the pulsating waveform may be a rectangular wave or a triangular wave. In this case, the control unit 400 may also set the amplitude and phase of the pulsating waveform to predetermined values.

[0032] The control unit 400 can also use the voltage applied to the capacitor 210 or the current flowing to the capacitor 210 to calculate the amount of pulsation contained in the second AC power output from the inverter 310, and can also use the voltage or current of the first AC power supplied from the commercial power supply 110 to calculate the amount of pulsation contained in the second AC power output from the inverter 310.

[0033] The operation of the control unit 400 is explained using a flowchart. Figure 4 This is a flowchart illustrating the operation of the control unit 400 included in the power conversion device 1 according to Embodiment 1. The control unit 400 obtains detection values ​​from each detection unit of the power conversion device 1 (step S1). Based on the obtained detection values, the control unit 400 controls the operation of the inverter 310, thereby reducing the current I3 flowing to the smoothing unit 200 (step S2).

[0034] Next, the hardware structure of the control unit 400 of the power conversion device 1 will be described. Figure 5 This diagram illustrates an example of the hardware structure of the control unit 400 included in the power conversion device 1 implementing Embodiment 1. The control unit 400 is implemented by a processor 91 and a memory 92.

[0035] Processor 91 is a CPU (also known as a Central Processing Unit, Central Processing Device, Processing Device, Arithmetic Device, Microprocessor, Microcomputer, Processor, DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Memory 92 can exemplify non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), and EEPROM (Electrically Erasable Programmable ROM). However, memory 92 is not limited to these and can also be a magnetic disk, optical disk, high-density disk, mini-disk, or DVD (Digital Versatile Disc).

[0036] As explained above, according to this embodiment, in the power conversion device 1, the control unit 400 controls the operation of the inverter 310 based on the detection values ​​obtained from each detection unit. It superimposes the pulsation of a frequency component corresponding to the frequency component of the current I1 flowing from the rectifier unit 130 onto the current I2 flowing to the inverter 310, thereby reducing the current I3 flowing to the smoothing unit 200. As a result, in the power conversion device 1, by reducing the current I3 flowing to the smoothing unit 200, a capacitor with a small ripple current tolerance can be used compared to the case without the control of this embodiment. Furthermore, in the power conversion device 1, by reducing the pulsating voltage of the capacitor voltage Vdc, the capacitance of the mounted capacitor 210 can be reduced compared to the case without the control of this embodiment. For example, in the case where the smoothing unit 200 is composed of multiple capacitors 210, the power conversion device 1 can reduce the number of capacitors 210 constituting the smoothing unit 200.

[0037] Furthermore, the power conversion device 1 controls the operation of the inverter 310 so that the pulsation in the second AC power is less than the pulsation of the power output from the rectifier 130. This suppresses the excessive pulsation component that overlaps with the current I2 flowing to the inverter 310. The overlap of pulsation components increases the effective value of the current flowing through the inverter 310, motor 314, etc., compared to the non-overlapping state. However, by suppressing the excessive pulsation component that overlaps, a system is provided that suppresses the current capacity of the inverter 310, the increase in inverter 310 losses, and the increase in motor 314 losses.

[0038] Furthermore, by performing the control described in this embodiment, the power conversion device 1 can suppress the vibration of the compressor 315 caused by the pulsation of the current I2.

[0039] Implementation method 2.

[0040] Figure 6 This is a diagram illustrating a structural example of the refrigeration cycle application device 900 according to Embodiment 2. The refrigeration cycle application device 900 of Embodiment 2 includes the power conversion device 1 described in Embodiment 1. The refrigeration cycle application device 900 of Embodiment 2 can be applied to products with a refrigeration cycle, such as air conditioners, cold storage rooms, freezers, and heat pump water heaters. Furthermore, in Figure 6 In the text, structural elements that have the same function as in Embodiment 1 are labeled with the same reference numerals as in Embodiment 1.

[0041] In the refrigeration cycle application equipment 900, a compressor 315 with a built-in motor 314, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910, as described in Embodiment 1, are installed via refrigerant piping 912.

[0042] Inside the compressor 315, there is a compression mechanism 904 for compressing refrigerant and a motor 314 for actuating the compression mechanism 904.

[0043] The refrigeration cycle application equipment 900 can operate in heating or cooling mode by switching the four-way valve 902. The compressor 904 is driven by a motor 314 that is controlled to have a variable speed.

[0044] During heating operation, as shown by the solid arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, then returns to the compression mechanism 904 through the four-way valve 902, indoor heat exchanger 906, expansion valve 908, outdoor heat exchanger 910, and the four-way valve 902.

[0045] During refrigeration operation, as shown by the dashed arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, then returns to the compression mechanism 904 through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906, and the four-way valve 902.

[0046] During heating operation, the indoor heat exchanger 906 acts as a condenser, releasing heat, while the outdoor heat exchanger 910 acts as an evaporator, absorbing heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser, releasing heat, while the indoor heat exchanger 906 acts as an evaporator, absorbing heat. The expansion valve 908 depressurizes the refrigerant, causing it to expand.

[0047] The structure shown in the above embodiments is an example, and it can also be combined with other known technologies, and the embodiments can be combined with each other. Some parts of the structure can also be omitted or changed without departing from the spirit.

[0048] Explanation of reference numerals in the attached figures

[0049] 1 Power conversion device, 2 Motor drive device, 110 Commercial power supply, 120 Reactor, 130 Rectifier section, 131-134 Rectifier elements, 200 Smoothing section, 210 Capacitor, 310 Inverter, 311a-311f Switching elements, 312a-312f Freewheeling diodes, 313a, 313b Current detection sections, 314 Motor, 315 Compressor, 400 Control section, 501 Voltage and current detection section, 502 Voltage detection section, 900 Refrigeration cycle application equipment, 902 Four-way valve, 904 Compression mechanism, 906 Indoor heat exchanger, 908 Expansion valve, 910 Outdoor heat exchanger, 912 Refrigerant piping.

Claims

1. A power conversion device, wherein, The power conversion device includes: The rectifier section rectifies the first AC power supplied from the commercial power source; A capacitor connected to the output terminal of the rectifier section; An inverter, connected to both ends of the capacitor, converts the power output from the rectifier and the capacitor into a second AC power and outputs it to a load with a motor; and The control unit controls only the operation of the inverter so that the second AC power, which includes pulsations corresponding to the pulsations of the power flowing from the rectifier to the capacitor, is output from the inverter to the load, thereby suppressing the current flowing to the capacitor.

2. The power conversion device according to claim 1, wherein, The control unit controls the operation of the inverter so that the pulsation in the second AC power output from the inverter is less than the pulsation in the power output from the rectifier.

3. The power conversion device according to claim 1 or 2, wherein, The control unit controls the amplitude and phase of the pulsations contained in the second AC power output from the inverter, such that the voltage ripple generated in the capacitor is less than the voltage ripple generated in the capacitor when the second AC power output from the inverter does not contain pulsations corresponding to the pulsations of the power flowing into the capacitor.

4. The power conversion device according to claim 1 or 2, wherein, The control unit controls the amplitude and phase of the pulsations contained in the second AC power output from the inverter, such that the current ripple flowing into and out of the capacitor is less than the current ripple generated in the capacitor when the second AC power output from the inverter does not contain pulsations corresponding to the pulsations of the power flowing into the capacitor.

5. The power conversion device according to any one of claims 1 to 4, wherein, When the first AC power is single-phase, the control unit controls the pulsating waveform of the current flowing to the inverter to a shape obtained by adding a DC component to a pulsating waveform with a frequency component that is twice the frequency of the first AC power as the main component; or when the first AC power is three-phase, the control unit controls the pulsating waveform of the current flowing to the inverter to a shape obtained by adding a DC component to a pulsating waveform with a frequency component that is six times the frequency of the first AC power as the main component.

6. The power conversion device according to claim 5, wherein, The pulsating waveform is set to the shape of the absolute value of a sine wave or the shape of a sine wave.

7. The power conversion device according to claim 6, wherein, The control unit sets at least one frequency component of the sine wave that is an integer multiple of the sine wave frequency as a predetermined amplitude and adds it to the pulsating waveform.

8. The power conversion device according to claim 5, wherein, Set the pulsating waveform to the shape of a rectangular wave or a triangular wave.

9. The power conversion device according to claim 8, wherein, The control unit sets the amplitude and phase of the pulsating waveform to predetermined values.

10. The power conversion device according to any one of claims 1 to 9, wherein, The control unit uses the voltage applied to the capacitor or the current flowing to the capacitor to calculate the amount of pulsation contained in the second AC power output from the inverter.

11. The power conversion device according to any one of claims 1 to 9, wherein, The control unit uses the voltage or current of the first AC power to calculate the amount of pulsation contained in the second AC power output from the inverter.

12. The power conversion device according to any one of claims 1 to 11, wherein, The capacitor is an electrolytic capacitor or a film capacitor.

13. The power conversion device according to any one of claims 1 to 12, wherein, The maximum value of the voltage ripple generated in the capacitor is less than twice the minimum value.

14. The power conversion device according to any one of claims 1 to 13, wherein, The rectifier performs full-wave rectification, and the voltage generated in the capacitor is not the full-wave rectified waveform of the commercial power supply.

15. A motor drive device, wherein, The motor drive device includes the power conversion device according to any one of claims 1 to 14.

16. A refrigeration cycle application device, wherein, The refrigeration cycle application equipment includes the power conversion device according to any one of claims 1 to 14.

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