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

Abstract

A power conversion device (1) comprises a converter (220) with an interleave circuit configuration and a totem-pole type, the converter (220) comprising: three first legs (133a, 133c, 133e) that are legs constituted by switching elements (131a to 131f); a second leg (140) that is constituted by rectifier diodes (141a to 141d); and the same number of reactors (120a, 120c, 120e) as the number of the first legs (133a, 133c, 133e) to be used, the reactors (120a, 120c, 120e) being disposed among an AC power supply (110) and the first legs (133a, 133c, 133e). The first legs (133a, 133c, 133e) are included in an intelligent power module (130) for a three-phase inverter. The second leg (140) is constituted by a two-phase diode bridge module (142), a three-phase diode bridge module, or the rectifier diodes of a discrete component.

Description

Power conversion devices, motor drive devices, and refrigeration cycle application equipment

[0001] The present disclosure relates to a power conversion device that performs power conversion, a motor drive device, and a refrigeration cycle application device.

[0002] Conventionally, there is an inverter module in which multiple switching elements used in an inverter and multiple diodes connected in parallel to each switching element are modularized into a single package. A power conversion device can be made smaller and less expensive by configuring an inverter using an inverter module. The inverter module is not limited to inverter applications and can also be used for applications other than inverters. For example, Patent Document 1 discloses technology for a power supply device that uses an inverter module as switching elements and diodes used in an interleaved circuit inside a converter.

[0003] JP 2014-212588 A

[0004] However, the conventional power supply uses an inverter module in the subsequent stage of a full-wave rectifier circuit composed of diodes. Therefore, even though the conventional power supply includes many switching elements, the number of times the diodes are turned on is greater than in a bridgeless circuit or the like, resulting in a problem of greater loss.

[0005] The present disclosure has been made in view of the above, and has an object to provide a power conversion device that can suppress an increase in loss while realizing miniaturization and low cost.

[0006] To solve the above-mentioned problems and achieve the object, a power conversion device according to the present disclosure includes a totem-pole converter with an interleaved circuit configuration, the converter including three first legs each configured with a switching element, a second leg each configured with a rectifier diode, and reactors, the number of which is equal to the number of first legs used, disposed between an AC power source that supplies AC power and the three first legs. The three first legs are included in an intelligent power module for a three-phase inverter. The second leg is configured with a two-phase diode bridge module, a three-phase diode bridge module, or a discrete rectifier diode.

[0007] The power conversion device according to the present disclosure has an effect of being able to suppress an increase in loss while realizing miniaturization and low cost.

[0008] FIG. 1 shows an example of the configuration of a power conversion device according to embodiment 1. FIG. 2 shows an example of the configuration of a power conversion device according to embodiment 1. FIG. 3 shows an example of the configuration of a power conversion device according to embodiment 1. FIG. 4 shows an example of the configuration of a power conversion device according to embodiment 1. FIG. 5 shows an example of the hardware configuration for realizing a control unit provided in a power conversion device according to embodiment 1. FIG. 6 shows an example of the configuration of a power conversion device according to embodiment 2. FIG. 7 shows an example of the configuration of a power conversion device according to embodiment 3. FIG. 8 shows an example of the configuration of a power conversion device according to embodiment 4. FIG. 9 shows an example of the configuration of a refrigeration cycle application device according to embodiment 5.

[0009] Hereinafter, a power conversion device, a motor drive device, and a refrigeration cycle applied device according to embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] First Embodiment. Fig. 1 is a first diagram showing a configuration example of a power conversion device 1 according to a first embodiment. The power conversion device 1 is connected to an AC power supply 110. The power conversion device 1 converts AC power supplied from the AC power supply 110, such as a commercial power supply, into DC power. The power conversion device 1 includes a converter 220 and a control unit 400. The converter 220 includes reactors 120a, 120c, and 120e, first legs 133a, 133c, and 133e, a second leg 140, and a capacitor 210. The converter 220 is an AC-DC converter that converts AC power into DC power. The converter 220 has an interleaved circuit configuration and is a totem-pole converter.

[0011] The three first legs 133a, 133c, and 133e are legs configured with switching elements. The first legs 133a, 133c, and 133e are included in the three-phase inverter intelligent power module 130. The first leg 133a is a leg in which switching elements 131a and 131b are connected in series. In the first leg 133a, a freewheeling diode 132a is connected in parallel to the switching element 131a, and a freewheeling diode 132b is connected in parallel to the switching element 131b. The first leg 133c is a leg in which switching elements 131c and 131d are connected in series. In the first leg 133c, a freewheeling diode 132c is connected in parallel to the switching element 131c, and a freewheeling diode 132d is connected in parallel to the switching element 131d. The first leg 133e is a leg in which the switching elements 131e and 131f are connected in series. In the first leg 133e, a free wheel diode 132e is connected in parallel to the switching element 131e, and a free wheel diode 132f is connected in parallel to the switching element 131f.

[0012] In the following description, the switching elements 131a to 131f will be referred to as switching elements 131 when they are not distinguished from one another, the freewheeling diodes 132a to 132f will be referred to as freewheeling diodes 132 when they are not distinguished from one another, and the first legs 133a, 133c, and 133e will be referred to as first legs 133 when they are not distinguished from one another. In this manner, the three-phase inverter intelligent power module 130 includes three first legs 133 each composed of the switching elements 131. In the converter 220, the first legs 133 each composed of the switching elements 131 are configured in a three-parallel interleaved configuration, and the three-phase inverter intelligent power module 130 is used in the three-parallel interleaved configuration. Note that in the example of FIG. 1, the switching elements 131 are IGBTs (insulated gate bipolar transistors), but this is not limiting. As will be described later, the switching element 131 may be a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like.

[0013] The second leg 140 is a leg that is made up of rectifier diodes 141a to 141d, and is configured, for example, by a two-phase diode bridge module 142 in which the rectifier diodes 141a to 141d are bridge-connected.

[0014] The reactors 120a, 120c, and 120e are disposed between the AC power supply 110 and the three first legs 133a, 133c, and 133e. Specifically, the reactor 120a has one end connected to the AC power supply 110 and the other end connected to the connection point between the switching element 131a and the switching element 131b of the first leg 133a. The reactor 120c has one end connected to the AC power supply 110 and the other end connected to the connection point between the switching element 131c and the switching element 131d of the first leg 133c. The reactor 120e has one end connected to the AC power supply 110 and the other end connected to the connection point between the switching element 131e and the switching element 131f of the first leg 133e.

[0015] Capacitor 210 is connected in parallel to both ends of second leg 140, and smoothes the DC voltage output from second leg 140. Capacitor 210 is, for example, an electrolytic capacitor or a film capacitor.

[0016] The control unit 400 controls the switching of the switching elements 131a to 131f included in the three-phase inverter intelligent power module 130 of the converter 220. For example, the control unit 400 controls the three switching elements 131b, 131d, and 131f of the lower arm to be alternately switched when the AC power supplied from the AC power supply 110 is positive, and controls the three switching elements 131a, 131c, and 131e of the upper arm to be alternately switched when the AC power supplied from the AC power supply 110 is negative. In this case, the converter 220 alternately switches the three switching elements 131b, 131d, and 131f of the lower arm when the AC power supplied from the AC power supply 110 is positive, and alternately switches the three switching elements 131a, 131c, and 131e of the upper arm when the AC power supplied from the AC power supply 110 is negative. This allows the power conversion device 1 to improve the power factor and boost the output voltage.

[0017] In this way, by using the three-phase inverter intelligent power module 130 in the converter 220, the power conversion device 1 can be made smaller and at lower cost.

[0018] Furthermore, since the power conversion device 1 has a totem-pole circuit configuration, the number of conducting diodes can be reduced compared to the circuit configuration of the power supply device of Patent Document 1 described in the background art, and therefore an increase in loss can be suppressed.

[0019] By conducting the upper arm switching elements 131a, 131c, and 131e as well, the power conversion device 1 distributes the current to many elements, dispersing the heat generated by losses and mitigating local temperature increases, making it possible to operate the elements at temperatures below their rated temperature using a cheaper heat dissipation mechanism.

[0020] Furthermore, generally, the longer the wiring between a switching element and a free wheel diode connected in parallel to its paired switching element in the same leg, the worse the noise generated when the switching element is switched due to the influence of parasitic impedance of the wiring, etc. However, in the power conversion device 1, the switching element 131 and the free wheel diode 132 connected in parallel to its paired switching element 131 in the same first leg 133 are in the same module, i.e., the three-phase inverter intelligent power module 130, so the wiring length can be made extremely short, and the generation of noise when the switching element 131 is switched can be greatly improved, i.e., the noise can be reduced.

[0021] 2A and 2B are diagrams illustrating how noise generation during switching of the switching element 131 can be improved in the power conversion device 1 according to the first embodiment. Fig. 2A shows, as a comparative example, a power conversion device 1 in which the switching elements 131a and 131b and the freewheeling diodes 132a and 132b are configured using discrete components 137a and 137b, while Fig. 2B shows the power conversion device 1 in which the switching elements 131a and 131b and the freewheeling diodes 132a and 132b are configured using discrete components 137a and 137b. The discrete component 137a includes a switching element 135a and a freewheeling diode 136a connected in parallel to the switching element 135a, and the discrete component 137b includes a switching element 135b and a freewheeling diode 136b connected in parallel to the switching element 135b. In this way, the power conversion device 1 can make the distance between the switching element 131a and the freewheel diode 132b, which are the internal wiring of the module, and the distance between the switching element 131b and the freewheel diode 132a shorter than the distance between the switching element 135a and the freewheel diode 136b, which are the on-circuit wiring shown in the comparative example, and the distance between the switching element 135b and the freewheel diode 136a.

[0022] In the example of FIG. 1 , the second leg 140 of the power conversion device 1 is configured by a two-phase diode bridge module 142, but this is not limited thereto and other configurations may be used. FIG. 3 is a second diagram showing an example configuration of the power conversion device 1 according to the first embodiment. The power conversion device 1 shown in FIG. 3 differs from the power conversion device 1 shown in FIG. 1 in that the second leg 140 is configured by a three-phase diode bridge module 143. The three-phase diode bridge module 143 is a module in which rectifier diodes 141a to 141f are bridge-connected. FIG. 4 is a third diagram showing an example configuration of the power conversion device 1 according to the first embodiment. The power conversion device 1 shown in FIG. 4 differs from the power conversion device 1 shown in FIG. 1 in that the second leg 140 is configured by discrete components 144a and 144b. The discrete component 144a is the rectifier diode 141a, and the discrete component 144b is the rectifier diode 141b. Thus, the second leg 140 may be comprised of a two-phase diode bridge module 142, a three-phase diode bridge module 143, or discrete components 144a, 144b rectifying diodes 141a, 141b.

[0023] Furthermore, even if the three-phase inverter intelligent power module 130 includes three first legs 133a, 133c, and 133e, the power conversion device 1 can operate without using one of the first legs 133 and using the remaining two first legs 133. FIG. 5 is a fourth diagram showing a configuration example of the power conversion device 1 according to the first embodiment. The power conversion device 1 shown in FIG. 5 is obtained by removing the reactor 120c from the power conversion device 1 shown in FIG. 1. In the power conversion device 1, the connection point between the switching element 131c and the switching element 131d of the first leg 133c is not connected to the AC power supply 110, so the switching element 131c and the switching element 131d of the first leg 133c are unused. In this case, the converter 220 operates as a two-parallel interleaved circuit in which one first leg 133 is not used in the three-phase inverter intelligent power module 130 and two first legs 133 are used. The unused first leg 133 may be the first leg 133a or the first leg 133e.

[0024] Although the power conversion device 1 shown in FIG. 5 has unnecessary components compared to the power conversion device 1 shown in FIG. 1 , the use of the three-phase inverter intelligent power module 130 can achieve effects such as miniaturization and low cost, suppression of loss increase, dispersion of heat generated by loss, and improvement of noise, as described above. Note that the second leg 140 of the power conversion device 1 shown in FIG. 5 can also be a three-phase diode bridge module 143 as shown in FIG. 3 , or discrete components 144 a, 144 b as shown in FIG. 4 . In the power conversion device 1, the converter 220 only needs to include the same number of reactors 120 as the first leg 133 used in the three-phase inverter intelligent power module 130.

[0025] Next, a description will be given of the hardware configuration of the control unit 400 included in the power conversion device 1. Fig. 6 is a diagram showing an example of a hardware configuration that realizes the control unit 400 included in the power conversion device 1 according to embodiment 1. The control unit 400 is realized by a processor 91 and a memory 92.

[0026] The processor 91 is a CPU (Central Processing Unit, also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Examples of memory 92 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). Memory 92 is not limited to these, and may also be a magnetic disk, optical disk, compact disk, minidisc, or DVD (Digital Versatile Disc).

[0027] As described above, according to this embodiment, the power conversion device 1 realizes the three first legs 133, each made up of switching elements 131, in the totem-pole converter 220 using the three-phase inverter intelligent power modules 130. This allows the power conversion device 1 to achieve effects such as miniaturization and low cost, suppression of loss increases, dispersion of heat generated by loss, and improvement of noise.

[0028] Second Embodiment In a second embodiment, a case where the power conversion device 1 includes an inverter in the subsequent stage of the converter 220 will be described.

[0029] FIG. 7 is a diagram illustrating a configuration example of a power conversion device 1 according to a second embodiment. The power conversion device 1 illustrated in FIG. 7 is configured by adding an inverter 310 to the power conversion device 1 illustrated in FIG. 1 . The power conversion device 1 is connected to an AC power source 110 and a motor 314. The power conversion device 1 converts first AC power supplied from the AC power source 110, such as a commercial power source, into DC power, and further converts the DC power into a second AC voltage having a desired amplitude and phase, and supplies the second AC voltage to the motor 314. As illustrated in FIG. 7 , the power conversion device 1 and the motor 314 constitute a motor drive device 2. Note that the configuration of the converter 220 is not limited to the example illustrated in FIG. 7 , and the configurations of the converter 220 illustrated in FIGS. 3 to 5 may also be used.

[0030] The inverter 310 is connected to the rear stage of the converter 220. As shown in Fig. 7, the inverter 310 is configured by a three-phase inverter intelligent power module 130. The configuration of the three-phase inverter intelligent power module 130 provided in the inverter 310 is similar to the configuration of the three-phase inverter intelligent power module 130 provided in the converter 220.

[0031] The control unit 400 controls the switching of the switching elements 131a to 131f included in the three-phase inverter intelligent power module 130 of the converter 220. In the second embodiment, the control unit 400 further controls the switching of the switching elements 131a to 131f included in the three-phase inverter intelligent power module 130 of the inverter 310.

[0032] As described above, in this embodiment, the power conversion device 1 uses three-phase inverter intelligent power modules 130 having the same configuration in the converter 220 and the inverter 310. This allows the three-phase inverter intelligent power modules 130 to be obtained more inexpensively by increasing the number of three-phase inverter intelligent power modules 130 used in the power conversion device 1. Furthermore, since the three-phase inverter intelligent power modules 130 can be obtained more inexpensively and the power conversion device 1 can be constructed inexpensively, the motor drive device 2 can also be constructed inexpensively.

[0033] Third Embodiment In a third embodiment, a case will be described in which MOSFETs are used as the switching elements 131 of the intelligent power module 130 for a three-phase inverter used in the converter 220.

[0034] FIG. 8 is a diagram illustrating a configuration example of a power conversion device 1 according to a third embodiment. In the power conversion device 1 illustrated in FIG. 8, the switching elements 131a to 131f of the power conversion device 1 illustrated in FIG. 1 are replaced with MOSFETs 134a to 134f. In the following description, when there is no need to distinguish between the MOSFETs 134a to 134f, they may be referred to as MOSFET 134. As described above, in this embodiment, the converter 220 includes the MOSFET 134 as the switching element 131. Also, in this embodiment, the converter 220 performs synchronous rectification under the control of the control unit 400. That is, the control unit 400 controls the switching of the MOSFETs 134a to 134f so that synchronous rectification is performed in the converter 220. For example, when the AC power supply is positive, the control unit 400 may turn on the switching element 131a at the timing when the free wheel diode 132a is turned on, turn on the switching element 131c at the timing when the free wheel diode 132c is turned on, and turn on the switching element 131e at the timing when the free wheel diode 132e is turned on. In the power conversion device 1, the control unit 400 controls the switching of the switching elements 131a to 131f, and therefore it is possible to grasp the timing when the free wheel diodes 132a, 132c, and 132e are turned on. Note that the synchronous rectification itself performed in the converter 220 of this embodiment is similar to general synchronous rectification, and therefore a detailed description thereof will be omitted.

[0035] Regarding the configuration of converter 220, the configuration of second leg 140 may be the same as that of second leg 140 shown in Fig. 3 or 4. Also, similar to converter 220 shown in Fig. 5, converter 220 shown in Fig. 8 may operate as two parallel interleaved circuits in which one first leg 133 is not used and two first legs 133 are used.

[0036] The power conversion device 1 shown in Fig. 8 can also be configured such that an inverter 310 is connected to the rear stage of the converter 220, as in the power conversion device 1 shown in Fig. 7. In this case, the three-phase inverter intelligent power module 130 used in the inverter 310 may have the switching element 131 replaced with a MOSFET 134 as in the three-phase inverter intelligent power module 130 provided in the converter 220 shown in Fig. 8, or may have a configuration including a switching element 131 such as an IGBT as in the inverter 310 shown in Fig. 7.

[0037] As described above, in this embodiment, the power conversion device 1 performs synchronous rectification by replacing the switching element 131 provided in the three-phase inverter intelligent power module 130 of the converter 220 with the MOSFET 134. This enables the power conversion device 1 to configure a low-loss power conversion system.

[0038] Fourth Embodiment In a fourth embodiment, a case will be described in which the power conversion device 1 includes a bootstrap circuit, a protection circuit, and the like.

[0039] Fig. 9 is a diagram illustrating a configuration example of a power conversion device 1 according to embodiment 4. The power conversion device 1 illustrated in Fig. 9 is obtained by adding, to the power conversion device 1 illustrated in Fig. 7 , a bootstrap circuit 602 including a high voltage integrated circuit (HVIC) 601a for the upper arms of switching elements 131a, 131c, and 131e, a low voltage integrated circuit (LVIC) 601b for the lower arms of switching elements 131b, 131d, and 131f, a protection circuit 603, and circuits for operating the protection circuit 603 and the like, for converter 220 and inverter 310. The bootstrap circuit 602 and the protection circuit 603 may be included in the intelligent power module 130 for a three-phase inverter, may be attached to the outside of the intelligent power module 130 for a three-phase inverter, or may be partially included in the intelligent power module 130 for a three-phase inverter.

[0040] The bootstrap circuit 602 and the protection circuit 603 are for the three-phase inverter intelligent power module 130. That is, in this embodiment, the power conversion device 1 uses the bootstrap circuit 602 for the three-phase inverter intelligent power module 130 as a drive power supply for the upper arm switching elements 131a, 131c, 131e provided in the converter 220 and the inverter 310. The power conversion device 1 also uses the protection circuit 603 for the three-phase inverter intelligent power module 130 as a protection circuit for the converter 220 and the inverter 310.

[0041] 9 , the power conversion device 1 includes a bootstrap circuit 602 and a protection circuit 603 for the converter 220, and a bootstrap circuit 602 and a protection circuit 603 for the inverter 310, but this is not limiting. The power conversion device 1 can also be configured to include the bootstrap circuit 602 but not the protection circuit 603 for the converter 220 and the inverter 310, or to include the protection circuit 603 but not the bootstrap circuit 602. The power conversion device 1 can also be configured to include at least one of the bootstrap circuit 602 and the protection circuit 603 for the converter 220, and at least one of the bootstrap circuit 602 and the protection circuit 603 for the inverter 310.

[0042] As described above, in the present embodiment, the power conversion device 1 uses the bootstrap circuit 602 for the three-phase inverter intelligent power module 130 as the drive power supply for the upper arm switching elements 131a, 131c, 131e provided in the converter 220 and the inverter 310, and uses the protection circuit 603 for the three-phase inverter intelligent power module 130 as the protection circuit for the converter 220 and the inverter 310. This makes it possible to easily add the bootstrap circuit 602, the protection circuit 603, etc. to the power conversion device 1 without having to design dedicated bootstrap circuits 602, protection circuits 603, etc.

[0043] Fifth Embodiment Fig. 10 is a diagram showing a configuration example of a refrigeration cycle-applied device 900 according to a fifth embodiment. The refrigeration cycle-applied device 900 according to the fifth embodiment includes the power conversion device 1 described in the second or fourth embodiment. The refrigeration cycle-applied device 900 according to the fifth embodiment can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters. In Fig. 10, components having the same functions as those in the second or fourth embodiment are denoted by the same reference numerals as those in the second or fourth embodiment.

[0044] The refrigeration cycle application equipment 900 includes a compressor 315 incorporating the motor 314 in embodiment 2 or embodiment 4, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910, which are attached via refrigerant piping 912.

[0045] Inside the compressor 315, a compression mechanism 904 that compresses the refrigerant and a motor 314 that operates the compression mechanism 904 are provided.

[0046] The refrigeration cycle device 900 can perform heating or cooling operation by switching the four-way valve 902. The compression mechanism 904 is driven by a motor 314 that is variably controlled in speed.

[0047] During heating operation, as shown by the solid arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910 and the four-way valve 902 and returns to the compression mechanism 904.

[0048] During cooling operation, as shown by the dashed arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, and 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.

[0049] During heating operation, the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat. The expansion valve 908 reduces the pressure of the refrigerant to expand it.

[0050] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0051] 1 Power conversion device, 2 Motor drive device, 91 Processor, 92 Memory, 110 AC power supply, 120a, 120c, 120e Reactor, 130 Intelligent power module for three-phase inverter, 131a to 131f, 135a, 135b Switching elements, 132a to 132f, 136a, 136b Freewheeling diodes, 133a, 133c, 133e First leg, 134a to 134f MOSFET, 137a, 137b, 144a, 144b Discrete components, 140 Second leg, 141a to 141f Rectifier diode, 142 Two-phase diode bridge module, 143 Three-phase diode bridge module, 210 Capacitor, 220 Converter, 310 Inverter, 314 Motor, 315 Compressor, 400 Control unit, 601a HVIC, 601b LVIC, 602 bootstrap circuit, 603 protection circuit, 900 refrigeration cycle application device, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 outdoor heat exchanger, 912 refrigerant piping.

Claims

1. a totem-pole converter having an interleaved circuit configuration, the converter including: three first legs each configured with a switching element; a second leg each configured with a rectifier diode; and reactors arranged between an AC power source that supplies AC power and the three first legs, the number of reactors being equal to the number of the first legs used; an inverter connected to a subsequent stage of the converter; Equipped with the three first legs are included in an intelligent power module for a three-phase inverter; the second leg is configured by a two-phase diode bridge module, a three-phase diode bridge module, or a rectifier diode of a discrete component; the inverter is configured by an intelligent power module for a three-phase inverter having the same configuration as the intelligent power module for a three-phase inverter including the three first legs; Power conversion device.

2. In the converter, one of the first legs is not used in the intelligent power module for a three-phase inverter, and two of the first legs are used, so that the converter operates as two parallel interleaved circuits. The power conversion device according to claim 1 .

3. a bootstrap circuit for the intelligent power module for a three-phase inverter is used as a drive power source for an upper arm switching element of the converter; The power conversion device according to claim 1 .

4. The protection circuit for the three-phase inverter intelligent power module is used as the protection circuit for the converter. The power conversion device according to claim 1 .

5. the converter alternately switches on and off three switching elements of a lower arm when the AC power is in a positive period, and alternately switches on and off three switching elements of an upper arm when the AC power is in a negative period; The power conversion device according to claim 1 .

6. The converter includes a metal oxide semiconductor field effect transistor as the switching element and performs synchronous rectification. The power conversion device according to claim 1 .

7. A motor drive device comprising the power conversion device according to any one of claims 1 to 6.

8. A refrigeration cycle device comprising the power conversion device according to any one of claims 1 to 6.