POWER CONVERTER AND AIR CONDITIONING DEVICE USING THE SAME

Abstract

Power converter (1), comprising: a rectifier (11) configured to rectify an alternating voltage supplied by an alternating current supply (2); a booster circuit (4) designed to amplify the voltage rectified by the rectifier (11); a smoothing capacitor (30) configured to smooth the voltage output by the booster circuit (4); a power module (10) configured to convert a DC voltage obtained by smoothing the output voltage by the smoothing capacitor (30) into an AC voltage; an overvoltage protection capacitor (15A) designed to absorb a surge voltage superimposed on the DC voltage to be input into the power module (10), an auxiliary overvoltage protection capacitor (15B) mounted outside the power module (10), a cooling unit designed to cool the power module (10), a printed circuit board (5) on which the power module (10) is mounted, where the overvoltage protection capacitor (15A) is mounted in the power module (10), the auxiliary overvoltage protection capacitor (15B) is mounted on the circuit board (5), and the cooling unit (10A) is arranged on the power module (10).

Description

Technical area

[0001] The present disclosure relates to a power converter configured to rectify and transform an alternating voltage using a transformer circuit having a switching element, and relates to an air conditioning device using the power converter. General state of the art

[0002] Until now, a large-capacity inverter designed to drive a motor, such as a compressor or a fan, of a refrigeration and air-conditioning device has used a system in which a DC bus voltage for driving the inverter is generated by a three-phase full-wave rectifier circuit. In the refrigeration and air-conditioning device, an attempt is made to increase the energy consumption efficiency during cooling and heating operations (Coefficient of Performance; COP) and the annual energy consumption efficiency during a year (Annual Performance Factor; APF). Therefore, compressor motors are generally designed so that an induced voltage is substantially equal to a power supply voltage near a rotational speed to be used in the rated operation of the refrigeration and air-conditioning device.

[0003] In this case, if an attempt is made to drive the motor in a high-speed range, for example, during an overload operation of the refrigeration and air-conditioning device where the speed is higher than that during the rated operation, the inverter cannot output a voltage greater than or equal to the power supply voltage. Therefore, the output voltage is saturated. Thus, a current of the compressor increases, and the increase in current causes a decrease in motor efficiency and an increase in inverter power loss. As a result, the conversion efficiency of the inverter decreases. Furthermore, the operating range may be restricted under restrictions on the demagnetization resistance of a magnet used in the compressor motor and the allowable current and temperature of a semiconductor used in the inverter.

[0004] In view of the above, a power converter including a booster circuit is proposed to broaden the output voltage range of the inverter (see, for example, Patent Literature 1). Patent Literature 1 discloses that a DC voltage command value is set for the booster circuit to proportionally increase the motor speed. Citation listPatent literature

[0005] Patent literature 1: JP 3 308 993 B2 Brief description of the inventionTechnical problem

[0006] However, in the method described in Patent Literature 1, the required DC voltage increases with the motor speed. When the power converter boosts the voltage to a higher voltage, a surge voltage to be generated by a switching operation increases. At this time, it is necessary to keep the boosted voltage within an allowable range, taking into account the magnitude of the surge voltage. Thus, when the surge voltage is generated, the set value of the boosted voltage is reduced. Thus, the booster circuit cannot boost the voltage to a desired DC voltage. On the other hand, the surge voltage increases with a wiring length of a circuit. Therefore, it is necessary to reduce the generated surge voltage depending on the wiring length.

[0007] The present disclosure has been made in view of the problems described above, and therefore, an object of the disclosed matters is to provide a power converter that can reduce a generated surge voltage depending on a wiring length and boost a voltage to a desired DC voltage, and to provide an air conditioning device using the power converter. Solution to the problem

[0008] A power converter according to an embodiment of the present disclosure includes a rectifier configured to rectify an alternating current (AC) voltage supplied from an alternating current power supply; a booster circuit configured to boost the voltage rectified by the rectifier; a smoothing capacitor configured to smooth the voltage output from the booster circuit; a power module configured to convert a direct current (DC) voltage obtained by smoothing the output voltage by the smoothing capacitor into an AC voltage; and a surge suppression capacitor configured to absorb a surge voltage superimposed on the direct current voltage to be input to the power module. The surge suppression capacitor is mounted in the power module. Advantageous effects of the invention

[0009] According to the embodiment of the present disclosure, the surge protection capacitor provided in the power module reduces the generated surge voltage depending on the wiring length. Furthermore, the surge protection capacitor absorbs the surge voltage input to the power module. Therefore, a set value of a voltage input to an inverter can be increased. Thus, the voltage can be boosted to a desired DC voltage. Short description of the drawings Fig. 1 is a circuit diagram showing an example of the structure of a power converter according to Embodiment 1. Fig. 2 is a schematic diagram for describing an inductance of wires in the power converter of Fig. 1. Fig. 3 is a graph showing an example of an input voltage of an inverter in a case where overvoltage protection capacitors are not mounted. Fig. 4 is a graph showing an example of an input voltage of an inverter in a case where overvoltage protection capacitors are mounted. Fig. 5 is a circuit diagram for describing the mounting of the power converter of Fig. 1. Fig. 6 is a schematic diagram showing an example of the structure of an air conditioning device according to Embodiment 2. Description of the embodimentsEmbodiment 1

[0010] A power converter according to Embodiment 1 of the present disclosure is described below. The power converter according to Embodiment 1 generates alternating currents each having a set frequency from a three-phase AC power supply and supplies the alternating currents to a load such as a motor of a compressor or an air sending device of an air conditioning device. [Structure of Power Converter 1]

[0011] Fig. 1 is a circuit diagram illustrating an example of the structure of a power converter 1 according to Embodiment 1. As shown in Fig. As shown in Figure 1, the power converter 1 converts AC power to DC power and then converts the DC power back to AC power. A three-phase AC power supply 2 is connected to an input side of the power converter 1, and a load 3 is connected to an output side of the power converter 1. The power converter 1 includes a module 10, a reactor 20, a smoothing capacitor 30, and an overvoltage protection capacitor 15B.

[0012] The module 10 contains a rectifier 11, a switching element 12, a backflow prevention element 13, an inverter 14, and an overvoltage protection capacitor 15A in one package. Furthermore, the choke 20, the switching element 12, and the backflow prevention element 13 form a booster circuit 4.

[0013] Rectifier 11 is connected to three-phase AC power supply 2. Rectifier 11 rectifies alternating current (AC) voltages of, for example, AC 200 V or AC 400 V supplied by three-phase AC power supply 2 and converts the AC voltages into a DC voltage. Examples of rectifier 11 include a three-phase full-wave rectifier in which six diodes are connected in a bridge. Rectifier 11 outputs the rectified voltage to booster circuit 4.

[0014] The booster circuit 4 amplifies the voltage rectified by the rectifier 11 to an arbitrary voltage. The reactor 20 forming the booster circuit 4 is connected to an output terminal of the rectifier 11. The backflow prevention element 13 is connected in series with the reactor 20. The switching element 20 is connected between the reactor 20 and the backflow prevention element 13.

[0015] The switching element 12 performs a switching operation in which the switching element 12 is turned on or off based on a switching signal supplied from a converter controller 50. Each of the switching element 12 and the backflow prevention element 13 is a wide bandgap semiconductor such as a silicon carbide (SiC) element, a gallium nitride (GaN) element, or a diamond element, which is wider in bandgap than a silicon (Si) element.

[0016] Note that the switching element 12 is not limited to the elements described above, but may be a semiconductor element such as a metal-oxide-semiconductor field-effect transistor (MOSFET) or an IGBT (insulated-gate bipolar transistor). Furthermore, the backflow prevention element 13 may be a backflow prevention diode such as a fast recovery diode.

[0017] The smoothing capacitor 30 smoothes the voltage output from the booster circuit 4. The inverter 14 includes a plurality of switching elements 14a and converts the DC voltage smoothed by the smoothing capacitor 30 into AC voltages serving as pulse width modulation (PWM) voltages. The switching element 14a for use in the inverter 14 is a semiconductor element such as an IGBT similar to the switching element 12 described above.

[0018] The load 3, such as a motor of a compressor of an air conditioning device, is connected to the inverter 14. The inverter 14 supplies alternating voltages, each having a set frequency, to the load 3. The inverter 14 is controlled by an inverter controller 40. Note that the switching element 14a for use in the inverter is not limited to the example described above, but may be a wide band-gap semiconductor such as silicon carbide (SiC).

[0019] The overvoltage protection capacitors 15A and 15B are provided to absorb a voltage divider circuit superimposed on the voltage input to the inverter 14. The overvoltage protection capacitor 15A is connected in parallel with the inverter 14. Furthermore, the overvoltage protection capacitor 15A is arranged near the inverter 14. The overvoltage protection capacitor 15B is connected in parallel with the smoothing capacitor 30.

[0020] The power converter 1 further includes the inverter controller 40, the conversion controller 50, a reactor current detector 60, a bus voltage detector 70, and load current detectors 80. The reactor current detector 60 detects a reactor current flowing through the reactor 20 and provides a detection result to the converter controller 50. The bus voltage detector 70 detects an output voltage accumulated in the smoothing capacitor 30 and provides a detection result to the inverter controller 40 and the converter controller 50. Each load current detector 80 detects a current output from the inverter 14 and provides a detection result to the inverter controller 40.

[0021] The inverter controller 40 performs PWM control of the inverter 14 based on the output voltage detected by the bus voltage detector 70 and the output currents detected by the load current detectors 80, so that the speed of the motor, which is the control target load 3, becomes a target speed. Various functions of the inverter controller 40 are implemented by executing software on a processor such as a microcomputer. Alternatively, the inverter controller 40 is hardware such as a circuit device that implements various functions.

[0022] The converter controller 50 generates a switching signal for the switching element 12 based on the output voltage detected by the bus voltage detector 70 and the inductor current detected by the inductor current detector 60, so that the voltage to be output by the booster circuit 4 becomes a target command voltage. Various functions of the converter controller 50 are implemented by executing software on a processor such as a microcomputer. Alternatively, the converter controller 50 is hardware such as a circuit device that implements various functions. [Operation of Power Converter 1]

[0023] Next, an operation of the power converter 1 according to Embodiment 1 will be described. As shown in Fig. As shown in Figure 1, when an AC voltage is supplied from the three-phase AC power supply 2 to the power converter 1, the supplied AC voltage is supplied to the rectifier 11. The rectifier 11 rectifies the supplied AC voltage and outputs a DC voltage. The DC voltage output from the rectifier 11 is supplied to the booster circuit 4. The booster circuit 4 amplifies the supplied DC voltage to a set voltage and outputs an output voltage V dc out of.

[0024] The converter controller 50 controls the operation of the booster circuit 4 to achieve a constant reactor current. When the switching element 12 in the booster circuit 4 is turned on, the DC voltage obtained by rectification by the rectifier 11 is applied to the reactor 20, and current conduction is prohibited by the backflow prevention element 13. On the other hand, when the switching element 12 is turned off, the backflow prevention element 13 is caused to conduct, and a voltage in a direction opposite to that when the switching element 12 is turned on is induced in the reactor 20. At this time, energy accumulated in the reactor 20 when the switching element 12 is turned on is transferred to the smoothing capacitor 30. In this case, the voltage to be output from the booster circuit 4 is controlled such that the on-duty ratio of the switching element 12 is controlled by the converter controller 50.

[0025] The output voltage amplified by the booster circuit 4 is collected and smoothed by the smoothing capacitor 30. The output voltage smoothed by the smoothing capacitor 30 is converted into three-phase alternating voltages by the inverter 14. The resulting alternating voltages are then supplied to the load 3.

[0026] The inverter controller 40 controls operations of the switching elements 14a of the inverter 14. The inverter controller 40 generates a switching signal based on detection results from the bus voltage detector 70 and the load current detectors 80 and supplies the switching signal to the switching elements 14a of the inverter 14.

[0027] The converter controller 50 controls the operation of the switching element 12 of the booster circuit 4. The converter controller 50 generates a switching signal based on detection results from the bus voltage detector 70 and the reactor current detector 60 and supplies the switching signal to the switching element 12. [Reduction of surge voltage]

[0028] Next, a description will be given of a method for reducing a surge voltage by the power converter 1 according to Embodiment 1. Generally, when a switching operation is performed, a surge voltage is generated along with the switching operation. The surge voltage generated at this time is calculated based on Expression (1). Here, L represents an inductance of a circuit board pattern and wires in the module 10, and di / dt represents an amount of charge in a current flowing through the wires. Surge voltage V=L×di / dt

[0029] The inductance L of the wires increases with the wiring length in the circuit. As shown by Expression (1), the surge voltage V increases with the wire length. That is, in Embodiment 1, when the switching element 12 performs the switching operation, the surge voltage V is generated depending on the wiring length, and a voltage on which the surge voltage V is superimposed is input to the inverter 14.

[0030] Here, if the surge voltage V increases depending on the wires, that is, if the voltage input to the inverter 14 is excessive, the switching elements 14a of the inverter 14 must have a withstand capacity against the excessive voltage. A withstand voltage value for the input voltage is set in each switching element 14a. However, if a surge voltage V exceeding the withstand voltage value is applied to the inverter 14, the switching elements 14a will be destroyed and the device will malfunction. Therefore, in the prior art, it is necessary that the amplification amount of the booster circuit 4 be adjusted so that the surge voltage V does not exceed the withstand voltage of each switching element 14a.

[0031] However, it is necessary to reduce the set value of the gain so that the maximum value of the voltage input to the inverter 14 does not exceed the withstand voltage of each switching element 14a. Therefore, high-efficiency motors cannot be used. Furthermore, even though the maximum value of the voltage input to the inverter 14 does not exceed the withstand voltage of each switching element 14a, the generated noise increases with the surge voltage V. Therefore, the cost required for noise reduction increases, or the power converter 1 may malfunction.

[0032] In view of the above, the surge protection capacitors 15A and 15B are provided in Embodiment 1 to reduce the surge voltage V in the voltage to be input to the inverter 14. Fig. 2 is a schematic diagram for describing the inductance L of the wires in the power converter 1 of Fig. 1. As in Fig. 2, wires connecting the inverter 14 and the smoothing capacitor 30 have inductances L A to L D on.

[0033] If it is taken into account that the inductances L A to L D distributed on the wires, the overvoltage protection capacitor 15B can generate a voltage due to the inductance L A generated surge voltage. Furthermore, the 15A surge protection capacitor can be used due to the inductances L B to L D generated surge voltages in addition to that due to the inductance L A absorb the generated surge voltage.

[0034] Note that the surge suppression capacitor 15A is arranged close to the inverter 14. Thus, the length of the wire connecting the surge suppression capacitor 15A and the inverter 14 decreases, and the surge voltage to be generated depending on the connecting wire can be reduced.

[0035] Fig. 3 is a graph showing an example of the input voltage of the inverter 14 in a case where the overvoltage protection capacitors 15A and 15B are not mounted. Fig. 4 is a graph showing an example of the input voltage of the inverter 14 in a case where the overvoltage protection capacitors 15A and 15B are provided. Fig. 3 and Fig. 4 illustrate examples of a case where the set values ​​of the input voltages represented by solid lines are equal.

[0036] In the case when the overvoltage protection capacitors 15A and 15B are not mounted as in Fig. 3, a voltage on which a surge voltage generated by the switching operation of the switching element 12 is superimposed is input to the inverter 14. In this case, the set value of the input voltage is adjusted so that the maximum value of the input voltage on which the surge voltage is superimposed does not exceed an allowable voltage of the inverter 14.

[0037] In a case where the overvoltage protection capacitors 15A and 15B are provided as in Fig. 4, on the other hand, the surge voltage superimposed on the voltage to be input to the inverter 14 is reduced. Furthermore, in this case, the set value of the input voltage is adjusted so that the maximum value of the input voltage on which the surge voltage is superimposed does not exceed the allowable voltage of the inverter 14. The surge voltage is reduced compared to that in the Fig. 3. Therefore, the input voltage can be increased as shown by the dotted line. Thus, the set value of the input voltage can be set higher than the set value in the example shown in Fig. Example shown in Figure 3.

[0038] As described above, when the surge suppression capacitors 15A and 15B are provided, the surge voltage superimposed on the voltage to be input to the inverter 14 is reduced. Furthermore, when the surge suppression capacitor 15A is arranged near the switching elements 14A of the inverter 14, the surge voltage to be generated depending on the wiring length and applied to the switching elements 14a is reduced to the extent possible. Therefore, in the power converter 1, the set value of the voltage to be applied to the inverter 14 can be increased depending on the reduction amount in the surge voltage. Thus, the load such as a motor can be supplied with electric power with higher efficiency to drive the load 3 by the power converter 1. [Installing the surge protection capacitors 15A and 15B]

[0039] Fig. 5 is a schematic diagram for describing the assembly of the power converter 1 of Fig. 1. As in Fig. 5, the module 10 of the power converter 1 is mounted on a printed circuit board 5. The overvoltage protection capacitor 15A is mounted in the module 10 and arranged near the switching element 14a of the inverter 14.

[0040] The module 10 is provided with a heat sink 10A serving as a cooling unit configured to cool the elements and other devices in the module 10. Therefore, the heat sink 10A can dissipate heat from, for example, the switching elements 14a in the module 10 and can also dissipate heat from the surge suppression capacitor 15A. Note that the method for cooling the elements in the module 10 is not limited to the method using the heat sink 10A, but any method can be used as long as a cooling function is provided.

[0041] Furthermore, the overvoltage protection capacitor 15B is mounted on the circuit board 5. The overvoltage protection capacitor 15B is mounted directly on the circuit board 5, and therefore, heat generated by the overvoltage protection capacitor 15B can be dissipated into the outside air.

[0042] As described above, in Embodiment 1, the surge suppression capacitor 15A is mounted in the module 10, and the surge suppression capacitor 15B is mounted on the circuit board 5. Thus, the two surge suppression capacitors 15A and 15B can individually absorb the surge voltage. Furthermore, each of the surge suppression capacitors 15A and 15B can be downsized because two surge suppression capacitors 15A and 15B are provided.

[0043] As described above, in the power converter 1 according to Embodiment 1, the surge protection capacitor 15A absorbs the surge voltage superimposed on the voltage to be input to the inverter 14. Thus, the set value of the voltage to be input to the inverter can be increased, and the voltage can be boosted to a desired voltage.

[0044] Furthermore, the module 10 includes the surge suppression capacitor 15A and the inverter 14, and therefore, the surge suppression capacitor 15A is arranged near the inverter 14. Thus, it is possible to reduce the surge voltage generated depending on the wire connecting the surge suppression capacitor 15A and the inverter 14.

[0045] In Embodiment 1, the surge protection capacitor 15B is still mounted outside the module 10. Thus, the two surge protection capacitors 15A and 15B can individually absorb the surge voltage, and each of the surge protection capacitors 15A and 15B can be downsized.

[0046] Further, the module 10 is provided with the heat sink 10A in Embodiment 1. Therefore, it is possible to dissipate heat of, for example, the switching elements 14a in the module 10 and also dissipate heat of the surge suppression capacitor 15A. Embodiment 2

[0047] Next, Embodiment 2 of the present disclosure will be described. In Embodiment 2, a description will be given of an example in which the power converter 1 described in Embodiment 1 is applied to an air conditioning device. [Structure of the air conditioning device 100]

[0048] Fig. 6 is a schematic diagram illustrating an example of the structure of an air conditioning device 100 according to Embodiment 1. The air conditioning device 100 of Fig. 6 performs cooling operation and heating operation by using a heat pump system.

[0049] As in Fig. 6, the air conditioning device 100 includes an outdoor unit 100A having a compressor 101, a refrigerant flow switching device 102, an outdoor heat exchanger 103, and an expansion device 104, and an indoor unit 100B including an indoor heat exchanger 105. In the air conditioning device 100, the compressor 101, the refrigerant flow switching device 102, the outdoor heat exchanger 103, the expansion device 104, and the indoor heat exchanger 105 are sequentially connected by refrigerant pipes to form a refrigerant circuit in which the refrigerant circulates through the refrigerant pipes.

[0050] Among the components described above, the compressor 101 includes a compression element 101a configured to compress the refrigerant, and a motor M coupled to the compression element 101a and serving as the load 3 to be supplied with electric power from the power converter 1. The power converter 1 is the power converter according to Embodiment 1, which is supplied with electric power from the three-phase AC power supply 2 and supplies the converted electric power to the motor M, so that the motor M is driven to rotate.

[0051] For example, the refrigerant flow switching device 102 is a four-way valve that changes the direction of refrigerant flow, thereby switching the cooling operation and the heating operation. The outdoor heat exchanger 103 exchanges heat between the refrigerant and outside air. The outdoor heat exchanger 103 functions as a condenser during cooling operation and as an evaporator during heating operation. The expansion device 104 expands the refrigerant. The indoor heat exchanger 105 exchanges heat between the refrigerant and inside air in an air-conditioned space. The indoor heat exchanger 105 functions as an evaporator during cooling operation and as a condenser during heating operation. [Operations of the air conditioning device 100]

[0052] Next, operations of the air conditioning device 100 according to Embodiment 2 will be described with reference to Fig. 6. Here, the cooling operation is described as an example. When the cooling operation is performed, the refrigerant flow switching device 102 changes a passage in advance so that the refrigerant discharged from the compressor 101 flows to the outdoor heat exchanger 103, and the refrigerant flowing out of the indoor heat exchanger 105 flows to the compressor 101. At this time, the outdoor heat exchanger 103 functions as the condenser, and the indoor heat exchanger 105 functions as the evaporator.

[0053] When the motor M of the compressor 101 is driven to rotate by the power converter 1, the compression element 101a of the compressor 101, coupled to the motor M, compresses a low-temperature and low-pressure refrigerant, and the compressor 101 discharges a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 101 flows into the outdoor heat exchanger 103, which functions as the condenser, via the refrigerant flow switching device 102.

[0054] The high-temperature, high-pressure gas refrigerant flowing into the outdoor heat exchanger 103 exchanges heat with outside air to dissipate the heat and becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows out of the outdoor heat exchanger 103. The expansion device 104 expands the high-pressure liquid refrigerant flowing out of the outdoor heat exchanger 103 to reduce the pressure of the refrigerant. Therefore, the refrigerant becomes a low-temperature, low-pressure two-phase gas-liquid refrigerant. The low-temperature, low-pressure two-phase gas-liquid refrigerant flows into the indoor heat exchanger 105, which functions as the evaporator.

[0055] The low-temperature, low-pressure two-phase gas-liquid refrigerant flowing into the indoor heat exchanger 105 exchanges heat with the air in the air-conditioned space to remove the heat and is evaporated to cool the indoor air. Therefore, the refrigerant becomes a low-temperature, low-pressure gas and flows out of the indoor heat exchanger 105. The low-temperature, low-pressure gas flowing out of the indoor heat exchanger 105 is drawn into the compressor 101 via the refrigerant flow switching device 102 and is compressed again. Then, the above-described operation is repeated.

[0056] Please note that Fig.6 illustrates the example in which the power converter 1 according to Embodiment 1 is applied to the compressor 101 of the air conditioning device 100, but the application of the power converter 1 is not limited to that in this example. For example, the power converter 1 can be applied to a drive power supply for a fan (not shown) configured to send air to the outdoor heat exchanger 103. Furthermore, the power converter 1 can be applied to, for example, a heat pump device, a refrigerator device, and other general refrigeration cycle devices.

[0057] As described above, in the refrigeration device 100 according to Embodiment 2, the compressor 101 provided on the refrigerant cycle is driven by electric power supplied from the power converter 1. Therefore, similar to Embodiment 1, the surge voltage can be reduced, and a motor with higher efficiency can be used as the motor M configured to drive the compressor 101. List of reference symbols

[0058] 1 Power converter 2 Three-phase AC power supply 3 Load 4 Booster circuit 5 Printed circuit board 10 Module 10A Heat sink 11 Rectifier 12 Switching element 13 Backflow prevention element 14 Inverter 14a Switching element 15A, 15B Surge protection capacitor 20 Reactor 30 Smoothing capacitor 40 Inverter controller 50 Converter controller 60 Reactor current detector 70 Bus voltage detector 80 Load current detector 100 Air conditioning device 100A Outdoor unit 100B Indoor unit 101 Compressor 101a Compression element 102 Refrigerant flow switching device 103 Outdoor heat exchanger 104 Expansion device 105 Indoor heat exchanger

Claims

A power converter (1), comprising: a rectifier (11) configured to rectify an alternating voltage supplied by an alternating power supply (2); a booster circuit (4) configured to amplify the voltage rectified by the rectifier (11); a smoothing capacitor (30) configured to smooth the voltage output by the booster circuit (4); a power module (10) configured to convert a direct voltage obtained by smoothing the output voltage by the smoothing capacitor (30) into an alternating voltage;an overvoltage protection capacitor (15A) configured to absorb a surge voltage superimposed on the DC voltage to be input to the power module (10), an auxiliary overvoltage protection capacitor (15B) mounted outside the power module (10), a cooling unit configured to cool the power module (10), a circuit board (5) on which the power module (10) is mounted, the overvoltage protection capacitor (15A) being mounted in the power module (10), the auxiliary overvoltage protection capacitor (15B) being mounted on the circuit board (5), and the cooling unit (10A) being arranged on the power module (10); Power converter (1) according to claim 1, wherein a first switching element (14a) is used for the power module (10), and the overvoltage protection capacitor (15A) is arranged adjacent to the first switching element (14a) of the power module (10). Power converter (1) according to claim 1 or 2, wherein the circuit board (5) is a double-sided circuit board with one side on which the power module (10) is mounted and another side on which the auxiliary overvoltage protection capacitor (15B) is mounted. Power converter (1) according to one of claims 1 to 3, wherein the overvoltage protection capacitor (15A) is mounted adjacent to the cooling unit (10A) of the power module (10). Power converter (1) according to one of claims 1 to 4, wherein a second switching element (12) is used for the booster circuit (4), and wherein at least one of the second switching element (12) of the booster circuit (4) and the first switching element (14a) of the power module (10) is made of a wide bandgap semiconductor. An air conditioning device (100) comprising:the power converter (1) according to any one of claims 1 to 5; anda refrigerant circuit through which refrigerant circulates, the refrigerant circuit being formed by sequentially connecting, via refrigerant pipes, a compressor (101) to be driven by electric power supplied from the power converter (1), an outdoor heat exchanger (103), an expansion device (104), and an indoor heat exchanger (105).

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