Power conversion device

Abstract

This power conversion device (20) is provided with a base (31), a semiconductor module (40) constituting an inverter, and a capacitor (50) connected in parallel with the inverter. In a Z direction in which the base (31) and the capacitor (50) are aligned, a module mounting part (3111) on one surface (311) of the base (31) is positioned above a capacitor mounting part (3112). The base (31) has a flow path (34) through which a refrigerant (35) flows. The flow path (34) has a module flow path part (344) and a capacitor flow path part (345). Among wall surfaces defining the flow path (34), an upper surface (3441) of the module flow path part (344) is positioned above an upper surface (3451) of the capacitor flow path part (345).

Description

Power Conversion Device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-26067 filed in Japan on February 23, 2024, the contents of which are incorporated by reference in their entirety.

[0002] The disclosure herein relates to power conversion devices.

[0003] Patent Document 1 discloses a motor drive device. The motor drive device includes a capacitor, a first inverter connected to one end of a winding, and a second inverter connected to the other end of the winding. The contents of the prior art document are incorporated by reference as an explanation of the technical elements in this specification.

[0004] International Publication No. 2022 / 038669

[0005] In Patent Document 1, a first inverter and a second inverter are mounted on the same circuit board, and a heat sink is fixed to the top surface of the inverter package. Arranging a heat sink to cool not only the inverter but also the capacitor results in a large amount of dead space on the circuit board, increasing the overall size. In response to this, a configuration could be considered in which the inverter and converter are cooled while suppressing the increase in size by using, for example, the bottom wall of the housing as a heat sink. However, if the inverter and capacitor are arranged on the same plane, such as the bottom surface of the housing, the wiring electrically connecting the capacitor and the inverter becomes long, resulting in increased inductance. Further improvements are needed in power conversion devices in terms of the above and other aspects not mentioned.

[0006] One disclosed object is to provide a power conversion device that can reduce inductance while improving cooling effect.

[0007] One aspect of the disclosure is a power conversion device comprising: a base having one surface; a semiconductor module including semiconductor elements constituting an inverter and arranged on the one surface; and a capacitor arranged on the one surface and connected in parallel to the inverter, wherein in the alignment direction of the base and the capacitor, the mounting portion of the semiconductor module on the one surface is located higher than the mounting portion of the capacitor, the base has a flow path through which a refrigerant flows, the flow path has a module flow path portion including a portion that overlaps with the semiconductor module in a planar view in the alignment direction, and a capacitor flow path portion including a portion that overlaps with the capacitor in a planar view, and of the wall surfaces defining the flow path, the upper surface of the module flow path portion is located higher in the alignment direction than the upper surface of the capacitor flow path portion.

[0008] According to the disclosed power conversion device, a base is provided so that the mounting portion of the semiconductor module is located above the mounting portion of the capacitor. This base structure allows the semiconductor module to be placed close to the top surface of the capacitor. This shortens the wiring length between the semiconductor module and the capacitor, thereby reducing inductance. In addition, a flow path is provided in the base so that the top surface of the module flow path portion is located above the top surface of the capacitor flow path portion. This allows effective cooling of not only the capacitor but also the semiconductor module placed close to the top surface of the capacitor. As a result, a power conversion device can be provided that can reduce inductance while increasing cooling effectiveness.

[0009] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings.

[0010] 6 is a diagram illustrating a power conversion circuit and a drive system. FIG. 7 is a diagram illustrating an example of an operating point map of a rotating electric machine. FIG. 8 is a diagram illustrating star connection drive. FIG. 9 is a diagram illustrating open connection drive. FIG. 10 is a plan view illustrating a power conversion device according to a first embodiment. FIG. 11 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG. 12 is a diagram illustrating the positional relationship between flow paths, semiconductor modules, and capacitors. FIG. 13 is a diagram illustrating another example of a power conversion circuit. FIG. 14 is a plan view illustrating a power conversion device according to a second embodiment. FIG. 15 is a cross-sectional view illustrating a power conversion device according to a third embodiment.

[0011] Hereinafter, several embodiments will be described with reference to the drawings. Note that in each embodiment, corresponding components are designated by the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment previously described may be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0012] The power conversion module of this embodiment is applied to, for example, a mobile object powered by a rotating electric machine, such as an electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an aircraft such as an electric vertical take-off and landing aircraft or a drone, a ship, a construction machine, or an agricultural machine.

[0013] First Embodiment First, a schematic configuration of a drive system for a moving body will be described with reference to FIG.

[0014] <Drive System for a Moving Body> As shown in FIG. 1 , a drive system 1 for a moving body includes a DC power supply 2 , a rotating electric machine 3 , and a power conversion circuit 4 .

[0015] The DC power supply 2 may be, for example, a rechargeable secondary battery such as a lithium ion battery, a nickel-metal hydride battery, etc. The DC power supply 2 may also be one that converts AC power into DC power and outputs it.

[0016] The rotating electric machine 3 is a three-phase rotating electric machine of an open winding type with an open neutral point. The rotating electric machine 3 has a U-phase winding 3U, a V-phase winding 3V, and a W-phase winding 3W. Hereinafter, the U-phase winding 3U, the V-phase winding 3V, and the W-phase winding 3W may be simply referred to as windings 3U, 3V, and 3W.

[0017] The rotating electric machine 3 functions, for example, as a drive source for a moving body, that is, as an electric motor. If the moving body is a vehicle, the rotating electric machine 3 generates torque for driving drive wheels (not shown). The rotating electric machine 3 is not limited to an electric motor. The rotating electric machine 3 may be a motor generator that functions as both an electric motor and a generator, or may be a generator.

[0018] The power conversion circuit 4 converts power between the DC power supply 2 and the rotating electric machine 3. The drive system 1 is a common power supply system in which the same DC power supply 2 supplies power to two inverters 8 and 9 (described later) to drive the rotating electric machine 3. The drive system 1 may include only one DC power supply 2 as illustrated in FIG. 1 , or may include multiple DC power supplies 2. The drive system 1 may include a power supply switch (not shown), such as an SMR, between the DC power supply 2 and the power conversion circuit 4. SMR is an abbreviation for System Main Relay. Turning on the power supply switch enables power supply from the DC power supply 2 to the rotating electric machine 3, and turning off the power supply switch cuts off the power supply from the DC power supply 2 to the rotating electric machine 3.

[0019] <Power Conversion Circuit> Next, the power conversion circuit 4 will be described with reference to Fig. 1. Fig. 1 shows an example of the power conversion circuit 4. The power conversion circuit 4 shown in Fig. 1 includes power supply lines 5 and 6, a smoothing capacitor 7, inverters 8 and 9, and a selector switch 10.

[0020] The power supply line 5 is a high-potential power line. The power supply line 5 is connected to the positive electrode of the DC power supply 2. The power supply line 5 may be referred to as a positive-side power supply line, a P line, or the like. The power supply line 5 has a wiring 5A. The wiring 5A is a part of the wiring that constitutes the power supply line 5. The wiring 5A is a part of the power supply line 5 that connects the inverter 8 and the inverter 9. The power supply line 6 is a low-potential power line. The power supply line 6 is connected to the negative electrode of the DC power supply 2. The power supply line 6 may be referred to as a negative-side power supply line, an N line, or the like. The power supply line 6 has a wiring 6A. The wiring 6A is a part of the wiring that constitutes the power supply line 6. The wiring 6A is a part of the power supply line 6 that connects the inverter 8 and the inverter 9. The power supply lines 5, 6 are configured to include a bus bar that is, for example, a metal plate.

[0021] The smoothing capacitor 7 mainly smoothes the DC voltage supplied from the DC power supply 2. The smoothing capacitor 7 is provided between the power supply lines 5 and 6. The positive electrode of the smoothing capacitor 7 is connected to the power supply line 5 between the DC power supply 2 and the inverters 8 and 9. The negative electrode of the smoothing capacitor 7 is connected to the power supply line 6 between the DC power supply 2 and the inverters 8 and 9. The smoothing capacitor 7 is connected in parallel to the inverters 8 and 9.

[0022] The inverters 8 and 9 are DC-AC conversion circuits. The inverter 8 is configured with upper and lower arm circuits 8HL for three phases. The upper and lower arm circuits 8HL are sometimes referred to as legs. The upper and lower arm circuit 8HL has an upper arm 8H and a lower arm 8L. The upper arm 8H and the lower arm 8L are connected in series between the power supply lines 5 and 6, with the upper arm 8H on the power supply line 5 side.

[0023] The connection point between the upper arm 8H and the lower arm 8L is connected to the winding of the corresponding phase in the rotating electric machine 3 via an output line 11. The inverter 8 has six arms. Each arm is configured with a switching element. The number of switching elements constituting each arm is not particularly limited. There may be one or more. When there are more than one switching elements, the multiple switching elements connected in parallel to each other are turned on and off at the same timing by a common gate drive signal (drive voltage).

[0024] The illustrated switching element is an n-channel MOSFET 8S. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. In the upper arm 8H, the drain terminal of the MOSFET 8S is connected to the power supply line 5. In the lower arm 8L, the source terminal of the MOSFET 8S is connected to the power supply line 6. The source terminal of the MOSFET 8S in the upper arm 8H and the drain terminal of the MOSFET 8S in the lower arm 8L are connected to each other.

[0025] A freewheeling diode 8D is connected in antiparallel to each MOSFET 8S. The diode 8D may be a parasitic diode (body diode) of the MOSFET 8S or may be provided separately from the parasitic diode. The anode terminal of the diode 8D is connected to the source terminal of the corresponding MOSFET 8S, and the cathode terminal is connected to the drain terminal.

[0026] The inverter 9 has the same configuration as the inverter 8. The inverter 9 is configured with upper and lower arm circuits 9HL for three phases. The upper and lower arm circuits 9HL have an upper arm 9H and a lower arm 9L. The upper arm 9H and the lower arm 9L are connected in series between the power supply lines 5 and 6, with the upper arm 9H on the power supply line 5 side.

[0027] The connection point between the upper arm 9H and the lower arm 9L is connected to the winding of the corresponding phase in the rotating electric machine 3 via an output line 12. The inverter 9 also has six arms. Each arm is configured with a switching element. The number of switching elements constituting each arm is not particularly limited. It may be one or more.

[0028] 1, an n-channel MOSFET 9S is used as the switching element constituting each arm. In the upper arm 9H, the drain terminal of the MOSFET 9S is connected to the power supply line 5. In the lower arm 9L, the source terminal of the MOSFET 9S is connected to the power supply line 6. The source terminal of the MOSFET 9S in the upper arm 9H and the drain terminal of the MOSFET 9S in the lower arm 9L are connected to each other. A freewheeling diode 9D is connected in antiparallel to each MOSFET 9S.

[0029] As described above, the high-potential terminals (drain terminals) of the upper arms 8H, 9H of the inverters 8, 9 are connected to the power supply line 5. The low-potential terminals (source terminals) of the lower arms 8L, 9L are connected to the power supply line 6. A node connecting the upper arm 8H and the lower arm 8L is connected to one end of the corresponding phase winding via an output line 11, and a node connecting the upper arm 9H and the lower arm 9L is connected to the other end of the corresponding phase winding via an output line 12. Specifically, one end of the U-phase winding 3U is connected to a node U1 of the U-phase upper and lower arm circuit 8HL, and the other end of the U-phase winding 3U is connected to a node U2 of the U-phase upper and lower arm circuit 9HL. One end of the V-phase winding 3V is connected to a node V1 of the V-phase upper and lower arm circuit 8HL, and the other end of the V-phase winding 3V is connected to a node V2 of the V-phase upper and lower arm circuit 9HL. One end of the W-phase winding 3W is connected to a node W1 of the W-phase upper and lower arm circuit 8HL, and the other end of the W-phase winding 3W is connected to a node W2 of the W-phase upper and lower arm circuit 9HL.

[0030] The switching elements constituting the inverters 8 and 9 are not limited to the MOSFETs described above. For example, IGBTs may be used. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. In the case of an IGBT, a freewheeling diode is also connected in anti-parallel.

[0031] The changeover switch 10 is provided on at least one of the power supply lines 5, 6, between the connection point of the inverter 8 and the connection point of the inverter 9. That is, the changeover switch 10 is provided on at least one of the lines 5A, 6A. When the changeover switch 10 is closed, it electrically connects the inverter 9 and the smoothing capacitor 7 (DC power supply 2). When the changeover switch 10 is open, it cuts off the connection between the inverter 9 and the smoothing capacitor 7. The changeover switch 10 is sometimes referred to as a switch, an open / close switch, etc. The changeover switch 10 may include, for example, a semiconductor switch or a mechanical switch. A mechanical switch is a switch that has mechanical contacts.

[0032] The illustrated changeover switch 10 is provided on the power supply line 5 (wire 5A). When the changeover switch 10 is closed, it electrically connects the high-potential terminal of the upper arm 9H of the inverter 9 to the smoothing capacitor 7 (DC power supply 2). When the changeover switch 10 is open, it cuts off the connection between the high-potential terminal of the upper arm 9H and the smoothing capacitor 7. The changeover switch 10 is a semiconductor switch, i.e., it has a switching element formed on a semiconductor chip. The switching element is not particularly limited. It may have the same configuration as the switching element constituting at least one of the inverters 8 and 9, or it may have a different configuration.

[0033] The illustrated switching element is an n-channel MOSFET 10S. A diode 10D is connected in anti-parallel to the MOSFET 10S. The diode 10D is, for example, a parasitic diode. The changeover switch 10 is arranged on the wiring 5A so that the drain terminal of the MOSFET 10S is on the inverter 8 side and the source terminal is on the inverter 9 side. In other words, the forward direction of the diode 10D is from the inverter 9 to the inverter 8.

[0034] When MOSFET 10S is turned on and the selector switch 10 is closed, the high potential side terminal of upper arm 9H is electrically connected to the smoothing capacitor 7. When the selector switch 10 is closed, the high potential side terminal of upper arm 8H is electrically connected to the high potential side terminal of upper arm 9H. When MOSFET 10S is turned off and the selector switch 10 is open, the electrical connection between the high potential side terminal of upper arm 9H and the smoothing capacitor 7 is interrupted. When the selector switch 10 is closed, the electrical connection between the high potential side terminal of upper arm 8H and the high potential side terminal of upper arm 9H is interrupted.

[0035] As illustrated in FIG. 1 , the power conversion circuit 4 may include a control unit (CTR) 13. The control unit 13 may include, for example, a processor, a memory, and a storage. The processor executes various processes by accessing the memory. The memory is a rewritable volatile storage medium. The memory is, for example, a RAM. RAM is an abbreviation for Random Access Memory. The storage is a rewritable nonvolatile memory. The storage may be realized by at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium. The storage may include multiple types of storage media, such as a ROM and a flash memory. ROM is an abbreviation for Read Only Memory.

[0036] The storage stores a program to be executed by the processor. The program causes the processor to execute multiple instructions to construct multiple functional units. The processing performed by the control unit 13 may be realized by software processing in which the processor executes the program, or may be realized by hardware processing using a dedicated electronic circuit. It may also be realized by a combination of software processing and hardware processing.

[0037] The control unit (CTR) 13 includes, for example, a drive command generating unit (DIG) 131 and a drive circuit unit (DC) 132. The drive command generating unit 131 controls the inverters 8 and 9. The drive command generating unit 131 generates drive commands (command signals) for controlling the on / off of the MOSFETs 8S and 9S and outputs the drive commands to the drive circuit unit 132. The drive command generating unit 131 generates the drive commands based on drive requests for the rotating electric machine 3, such as torque command values ​​input from a higher-level ECU (not shown), and signals detected by various sensors. The various sensors may include current sensors, rotation angle sensors, voltage sensors, and the like (not shown). The current sensors detect phase currents flowing through the windings 3U, 3V, and 3W of each phase. The rotation angle sensors detect the rotation angle of the rotor of the rotating electric machine 3. The voltage sensor detects the voltage across the smoothing capacitor 7.

[0038] The drive command generation unit 131 controls the changeover switch 10. The drive command generation unit 131 generates a drive command for controlling the on / off of the MOSFET 10S and outputs the drive command to the drive circuit unit 132. The drive circuit unit 132 is sometimes referred to as a driver. The drive circuit unit 132 can independently control the on / off of the MOSFET 8S, MOSFET 9S, and MOSFET 10S based on the drive command. For convenience, signal lines for transmitting drive signals from the control unit 13 to each switching element are omitted in FIG. 1 .

[0039] 1 , the power conversion circuit 4 may include a filter circuit 14. The filter circuit 14 is a circuit for reducing noise such as electromagnetic noise. The filter circuit 14 is disposed, for example, between the DC power supply 2 and the smoothing capacitor 7. The filter circuit 14 is connected in parallel to the smoothing capacitor 7. The filter circuit 14 is connected in parallel to the inverter 8. The filter circuit 14 is configured to include, for example, a coil and a capacitor.

[0040] The power conversion circuit 4 may include a snubber circuit (not shown). The power conversion circuit 4 may include, for example, a snubber circuit connected in parallel to the inverter 9, i.e., the upper and lower arm circuits 9HL. The power conversion circuit 4 may include a snubber circuit connected in parallel to the inverter 8, i.e., the upper and lower arm circuits 8HL. The power conversion circuit 4 may include a snubber circuit connected in parallel to the inverter 8 and a snubber circuit connected in parallel to the inverter 9.

[0041] <Star Connection Drive and Open Connection Drive> Next, star connection drive and open connection drive will be described with reference to Figures 2, 3, and 4. Figure 2 shows an example of an operating point map of a rotating electric machine, with the horizontal axis representing rotation speed and the vertical axis representing torque. Figure 3 is a diagram showing star connection drive. Figure 4 is a diagram showing open connection drive. For convenience, the control unit 13 and the filter circuit 14 are omitted from Figures 3 and 4.

[0042] As shown in Figure 2, the driving range of the rotating electric machine 3 is divided into two ranges depending on the rotation speed and torque. One of the driving ranges is a star connection driving range. The star connection driving range is, for example, a normal range. The other driving range is an open connection driving range. The open connection driving range is a range of higher rotation speeds or higher torques than the star connection driving range.

[0043] When the operating point is in the star connection drive region, the control unit 13 executes star connection drive control. Star connection drive is sometimes called Y drive. The control unit 13 controls the MOSFETs 8S, 9S, and 10S so that the windings 3U, 3V, and 3W are in a star connection state. Specifically, as shown in FIG. 3, the control unit 13 turns off the MOSFET 10S and opens the selector switch 10. The control unit 13 also neutralizes the inverter 9. As shown in FIG. 3, for example, the control unit 13 turns on the MOSFETs 9S of the upper arms 9H of all phases and turns off the MOSFETs 9S of the lower arms 9L of all phases. The control unit 13 then controls the MOSFETs 8S of the inverter 8 according to drive requests, etc.

[0044] FIG. 3 shows one current conduction pattern in star-connection drive. The dashed-dotted arrows in FIG. 3 indicate an example of a current path. FIG. 3 shows the current path when the MOSFET 8S in the U-phase upper arm 8H and the MOSFET 8S in the W-phase lower arm 8L are turned on. In the example shown in FIG. 3, the upper arm 9H of the inverter 9 is turned on and the lower arm 9L is turned off. The current flows in the following order: U-phase upper arm 8H → node U1 → U-phase winding 3U → node U2 → U-phase upper arm 9H → W-phase upper arm 9H → node W2 → W-phase winding 3W → node W1 → W-phase lower arm 8L. In this way, in star-connection drive, current flows without passing through the selector switch 10.

[0045] When the operating point is in the open connection drive region, the control unit 13 executes open connection drive control. Open connection drive is sometimes referred to as H drive. The control unit 13 turns on the MOSFET 10S and closes the selector switch 10. The control unit 13 also opens the neutral point of the inverter 9. Opening the neutral point forms an open connection circuit of the U-phase upper and lower arm circuits 8HL, 9HL via the U-phase winding 3U. Similarly, an open connection circuit of the V-phase upper and lower arm circuits 8HL, 9HL via the V-phase winding 3V is formed. An open connection circuit of the W-phase upper and lower arm circuits 8HL, 9HL via the W-phase winding 3W is formed. The control unit 13 regards each phase as an independent open connection circuit and controls the applied voltage for each phase.

[0046] Figure 4 shows one current conduction pattern in open connection drive. The two-dot chain arrow in Figure 4 indicates one example of a current path. Figure 4 shows the current path when MOSFET 8S in W-phase lower arm 8L and MOSFET 9S in W-phase upper arm 9H are turned on. Current flows in the following order: changeover switch 10 → W-phase upper arm 9H → node W2 → W-phase winding 3W → node W1 → W-phase lower arm 8L. In this way, in open connection drive, current flows via changeover switch 10.

[0047] As described above, the power conversion circuit 4 is configured to be switchable between star connection drive and open connection drive. The power conversion circuit 4 is configured to be able to execute star connection drive. The power conversion circuit 4 is configured to be able to execute open connection drive. By executing open connection drive instead of star connection drive, it is possible to output a higher rotation range or a higher torque range.

[0048] <Power Conversion Device> Next, a power conversion device will be described with reference to Figs. 5, 6, and 7. Fig. 5 is a plan view showing an example of a power conversion device. Fig. 5 shows a simplified view of each element constituting the power conversion device. For convenience, some elements such as a circuit board are omitted from Fig. 5. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 5. Fig. 7 is a plan view showing the positional relationship between the flow path, semiconductor module, and capacitor. In Fig. 7, the semiconductor module and capacitor are indicated by two-dot chain lines.

[0049] The power conversion device 20 provides the above-described power conversion circuit 4. The illustrated power conversion device 20 includes a housing 30, a semiconductor module 40, a capacitor 50, a terminal block 60, and circuit boards 70, 71, and 72. Hereinafter, the arrangement direction (stacking direction) of the base 31 and the capacitor 50 is referred to as the Z direction. A direction perpendicular to the Z direction is referred to as the Y direction. A direction perpendicular to both the Y direction and the Z direction is referred to as the X direction. The X direction, Y direction, and Z direction are mutually orthogonal. Unless otherwise specified, a shape viewed from the Z direction, in other words, a shape along the XY plane defined by the X direction and the Y direction, is referred to as a planar shape. The planar view from the Z direction may be simply referred to as a planar view. When describing two relative positions, one position closer to the capacitor mounting portion 3112 in the Z direction may be referred to as the lower position, and another position farther from the capacitor mounting portion 3112 may be referred to as the upper position.

[0050] <Housing> The housing 30 houses other elements that constitute the power conversion device 20. The housing 30 may be a metal housing made of a metal material such as aluminum, or a resin housing made of a resin material. The housing may also be a housing containing a metal material and a resin material. To dissipate heat generated by the semiconductor module 40, the capacitor 50, etc., it is preferable to use a housing containing a metal material, more preferably a metal housing. The housing 30 may be made of a single member, or may be made by assembling multiple members.

[0051] The illustrated housing 30 has a base 31, side walls 32, and a cover 33. The base 31 and side walls 32 are formed using a metal material including, for example, aluminum. The base 31 and side walls 32 are formed by aluminum die-casting. The base 31 has one surface 311 and a back surface 312 that is the surface opposite to the one surface 311. The semiconductor module 40 and the capacitor 50 are arranged on the one surface 311. The base 31 supports the semiconductor module 40 and the capacitor 50. The illustrated base 31 forms the bottom wall of the housing 30.

[0052] The one surface 311 has a module mounting portion 3111 and a capacitor mounting portion 3112. The module mounting portion 3111 includes a portion where the semiconductor module 40 is arranged. The capacitor mounting portion 3112 includes a portion where the capacitor 50 is arranged. The module mounting portion 3111 and the capacitor mounting portion 3112 are each, for example, flat surfaces that are approximately perpendicular to the Z direction. The module mounting portion 3111 and the capacitor mounting portion 3112 are located at different positions in the Z direction, and the module mounting portion 3111 is located higher than the capacitor mounting portion 3112. The one surface 311 is not flat overall, but has an uneven shape. On the one surface 311, the module mounting portion 3111 protrudes upward, and the capacitor mounting portion 3112 is recessed.

[0053] The rear surface 312 may be a flat surface that is substantially perpendicular to the Z direction as a whole, or may have an uneven shape. In the illustrated base 31, the rear surface 312 has an uneven shape. The rear surface 312 has a module directly below 3121 and a capacitor directly below 3122. The module directly below 3121 includes a portion that overlaps with the semiconductor module 40 in a plan view. The capacitor directly below 3122 includes a portion that overlaps with the capacitor 50 in a plan view. The module directly below 3121 and the capacitor directly below 3122 are positioned at different positions in the Z direction, and the module directly below 3121 is located higher than the capacitor directly below 3122. The rear surface 312 is also not flat as a whole but has an uneven shape. On the rear surface 312, the capacitor directly below 3122 protrudes downward, and the module directly below 3121 is recessed relative to the capacitor directly below 3122.

[0054] The sidewall 32 is continuous with the base 31. The illustrated sidewall 32 has a first sidewall portion 321, a second sidewall portion 322, and a third sidewall portion 323. The first sidewall portion 321, together with the base 31, defines an accommodation space 301 that accommodates the semiconductor module 40, the capacitor 50, the circuit boards 70 and 71, etc. The first sidewall portion 321 is continuous with the outer peripheral edge of the base 31 and extends upward. The first sidewall portion 321 has a cylindrical shape that extends in the Z direction. The first sidewall portion 321 surrounds one surface 311.

[0055] The second side wall portion 322 and the third side wall portion 323, together with the base 31, define an accommodation space 302 that accommodates the circuit board 72. The accommodation space 302 is configured to include an accommodation region 302S. The accommodation region 302S is an area where the module directly below 3121 is recessed with respect to the capacitor directly below 3122. The second side wall portion 322 is continuous with the outer peripheral edge of the base 31 and extends downward. The second side wall portion 322 is continuous with the outer peripheral edge of the base 31 that is on the semiconductor module 40 side in the alignment direction of the semiconductor module 40 and the capacitor 50, i.e., in the Y direction.

[0056] The third side wall 323 extends downward from the rear surface 312 of the base 31 at an intermediate position in the Y direction. The third side wall 323 is provided near the boundary (step) between the capacitor directly below the capacitor portion 3122 on the rear surface 312 and the module directly below the capacitor portion 3121. The lower end position of the third side wall 323 in the Z direction is approximately the same as the lower end position of the second side wall 322. The second side wall 322 and the third side wall 323 are connected to each other and form a cylindrical shape. The second side wall 322 and the third side wall 323 surround a portion of the rear surface 312, including the module directly below the capacitor portion 3121.

[0057] The cover 33 may be formed using the same material as the base 31 and the side wall 32, or may be formed using a different material. The cover 33 closes the openings of the cylindrical second side wall portion 322 and the cylindrical third side wall portion 323. With the circuit board 72 disposed in the accommodation space 302, the cover 33 is fixed to the side wall 32.

[0058] The base 31 provides a cooling function for cooling the semiconductor module 40, the capacitor 50, and the like. For this reason, the base 31 is sometimes referred to as a cooler. The base 31 has a flow path 34. The flow path 34 is a hollow portion that is connected to an inlet 36 for the coolant 35 and an outlet 37 for the coolant 35. The flow path 34 is formed by molding using a core. The coolant 35 may be a phase-change coolant such as water or ammonia, or a phase-non-change coolant such as an ethylene glycol-based coolant. The coolant 35 may be, for example, LLC. LLC is an abbreviation for long life coolant.

[0059] The inlet 36 and the outlet 37 are arranged across the side wall 32 and the base 31. The inlet 36 and the outlet 37 are attached to the first side wall 3211 of the first side wall 321 that is on the capacitor 50 side in the Y direction. The inlet 36 and the outlet 37 are aligned in the X direction. The inlet 36 and the outlet 37 are connected to a pump (not shown). The refrigerant 35 is supplied to the flow path 34 via the inlet 36. The refrigerant 35 that has flowed through the flow path 34 is discharged to the outside of the flow path 34 via the outlet 37.

[0060] The flow path 34 includes an inlet path 341, a discharge path 342, and a connecting path 343. One end of the inlet path 341 opens into the first side wall portion 3211, and an inlet 36 is attached to this end. The inlet path 341 has a crank shape in plan view. The inlet path 341 has Y-direction extension portions 3411 and 3412 and an X-direction extension portion 3413. The Y-direction extension portions 3411 and 3412 extend in the Y direction. The inlet 36 is attached to the end of the Y-direction extension portion 3411. A portion of the Y-direction extension portion 3411 overlaps the capacitor 50 in plan view. A portion of the Y-direction extension portion 3412 overlaps the capacitor 50 in plan view, and another portion overlaps the semiconductor module 40.

[0061] The X-direction extending portion 3413 is provided between the Y-direction extending portions 3411 and 3412. The X-direction extending portion 3413 extends in the X direction. The X-direction extending portion 3413 overlaps the capacitor 50 in a plan view. One of the ends of the X-direction extending portion 3413 is connected to the Y-direction extending portion 3411, and the other end is connected to the Y-direction extending portion 3412.

[0062] One end of the discharge path 342 opens into the first sidewall portion 3211, and the discharge port 37 is attached to this end. The discharge path 342 extends generally in the Y direction. The discharge path 342 has an expanded portion 3421 and a contracted portion 3422. The discharge port 37 is attached to the end of the expanded portion 3421. The expanded portion 3421 has a length, i.e., a width, in a direction perpendicular to the extension direction (X direction) greater than that of the contracted portion 3422. The expanded portion 3421 extends from the open end to a position overlapping the end of the capacitor 50 on the semiconductor module 40 side. A portion of the expanded portion 3421 overlaps the capacitor 50 in a plan view, and another portion overlaps the semiconductor module 40. By providing the X-direction extending portion 3413 and the expanded portion 3421, the flow path 34 overlaps most of the capacitor 50.

[0063] The connecting path 343 overlaps at least a portion of the semiconductor module 40 in a plan view. The connecting path 343 is provided above the inlet path 341 and the outlet path 342 in the Z direction. The connecting path 343 extends generally in the X direction. A slit 3431 is provided on the underside of the end of the connecting path 343 that overlaps with the inlet path 341. The slit 3431 connects the connecting path 343 and the inlet path 341 so that the coolant 35 can flow therethrough. A slit 3432 is provided on the underside of the end of the connecting path 343 that overlaps with the outlet path 342. The slit 3432 connects the connecting path 343 and the outlet path 342 so that the coolant 35 can flow therethrough.

[0064] The connecting path 343 has a lower layer portion 3433 and an upper layer portion 3434. The lower layer portion 3433 is located below the upper layer portion 3434. Slits 3431 and 3432 are provided in the lower layer portion 3433. In a plan view, the area of ​​the upper layer portion 3434 is larger than the area of ​​the lower layer portion 3433. In the illustrated connecting path 343, the upper layer portion 3434 contains the lower layer portion 3433. In a plan view, the upper layer portion 3434 (connecting path 343) contains the semiconductor module 40.

[0065] Coolant 35 is supplied to inlet passage 341 of flow path 34 through inlet 36 and flows into connecting passage 343 through slit 3431. Coolant 35 that has flowed through connecting passage 343 flows from connecting passage 343 through slit 3432 into discharge passage 342 and is discharged to the outside of flow path 34 through discharge port 37. The outline arrows in Figure 7 indicate the direction of coolant flow.

[0066] The flow path 34 has a module flow path section 344, a capacitor flow path section 345, and a step path 346. The module flow path section 344 includes a portion that overlaps with the semiconductor module 40 in a plan view. The capacitor flow path section 345 includes a portion that overlaps with the capacitor 50 in a plan view. The step path 346 connects the module flow path section 344 and the capacitor flow path section 345. The module flow path section 344 is composed of a portion of the inlet path 341, a portion of the outlet path 342, and a connecting path 343. The capacitor flow path section 345 is composed of a portion of the inlet path 341 including the X-direction extending portion 3413 and a portion of the outlet path 342 including the widened portion 3421. The step path 346 is composed of a portion of the inlet path 341 including the Y-direction extending portion 3412 and a portion of the outlet path 342 including the narrowed portion 3422. The step path 346 has a crank shape in the YZ plane. A storage area 302S is provided next to the step path 346 in the Y direction.

[0067] The module flow path section 344 has an upper surface 3441 and a lower surface 3442 opposite to the upper surface 3441. The condenser flow path section 345 has an upper surface 3451 and a lower surface 3452 opposite to the upper surface 3451. The upper surface 3441 is a wall surface among the inner wall surfaces of the base 31 that define the flow path 34, which defines the upper end of the module flow path section 344. The lower surface 3442 is a wall surface among the inner wall surfaces of the base 31 that define the flow path 34, which defines the lower end of the module flow path section 344. The upper surface 3451 is a wall surface among the inner wall surfaces of the base 31 that define the flow path 34, which defines the upper end of the condenser flow path section 345. The lower surface 3452 is a wall surface among the inner wall surfaces of the base 31 that define the flow path 34, which defines the lower end of the condenser flow path section 345.

[0068] 6, the upper surface 3441 is located higher than the upper surface 3451. The lower surface 3442 is located higher than the lower surface 3452. The module flow path section 344 is deeper than the condenser flow path section 345 in the Z direction.

[0069] The housing 30 may have a cover that covers the storage space 301. The housing 30 may have the storage space only on one surface 311 side of the base 31. The housing 30 may be configured without the side wall 32 and the cover 33. In other words, the housing 30 may have only the base 31.

[0070] <Semiconductor Module> The semiconductor module 40 constitutes the upper and lower arm circuits 8HL, 9HL described above, i.e., the inverters 8, 9. The semiconductor module 40 may also be referred to as a power module, a semiconductor device, an inverter component, or the like. The power conversion device 20 includes at least one semiconductor module 40. One (single) semiconductor module 40 may constitute the inverters 8, 9, or one of the semiconductor modules 40 may constitute the inverter 8 and another of the semiconductor modules 40 may constitute the inverter 9. A plurality of semiconductor modules 40 may constitute the inverter 8, and a plurality of other semiconductor modules 40 may constitute the inverter 9.

[0071] The illustrated power conversion device 20 includes one semiconductor module 40. The semiconductor module 40 includes a plurality of semiconductor elements 41, a changeover switch 42, a substrate 43, wiring members 44, a sealing body 45, and external connection terminals.

[0072] The semiconductor element 41 is formed by forming a switching element on a semiconductor substrate made of silicon (Si) or a wide bandgap semiconductor with a wider bandgap than silicon. The switching element has a vertical structure so that the main current flows in the thickness direction of the semiconductor substrate. Examples of wide bandgap semiconductors include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond. The semiconductor element 41 is sometimes called a power element, a semiconductor chip, or the like.

[0073] The illustrated semiconductor element 41 is formed by forming an n-channel MOSFET and a diode on a semiconductor substrate made of SiC. The MOSFET has a vertical structure so that a main current flows in the thickness direction of the semiconductor element 41 (semiconductor substrate). The semiconductor element 41 has main electrodes (not shown) on both sides of the semiconductor element 41 in the thickness direction. The semiconductor element 41 has a source electrode on the front side and a drain electrode on the back side as main electrodes. The source electrode is formed on a portion of the front side. The drain electrode is formed on almost the entire back side. The main current flows between the drain electrode and the source electrode. The semiconductor element 41 has a pad (not shown) that is a signal electrode on the surface where the source electrode is formed. The semiconductor element 41 is arranged so that its thickness direction is approximately parallel to the Z direction.

[0074] The illustrated semiconductor element 41 includes semiconductor elements 411H, 411L, 412H, and 412L. The semiconductor elements 411H and 411L constitute the inverter 8 of the power conversion circuit 4. The semiconductor element 411H constitutes the upper arm 8H, and the semiconductor element 411L constitutes the lower arm 8L. The semiconductor elements 411H and 411L provide the above-mentioned MOSFET 8S and diode 8D. The semiconductor elements 412H and 412L constitute the inverter 9 of the power conversion circuit 4. The semiconductor element 412H constitutes the upper arm 9H, and the semiconductor element 412L constitutes the lower arm 9L. The semiconductor elements 412H and 412L provide the above-mentioned MOSFET 9S and diode 9D.

[0075] The semiconductor module 40 includes three semiconductor elements 411H and three semiconductor elements 411L to form a three-phase upper and lower arm circuit 8HL. The semiconductor module 40 includes three semiconductor elements 412H and three semiconductor elements 412L to form a three-phase upper and lower arm circuit 9HL. The semiconductor elements 411H and 411L and the semiconductor elements 412H and 412L are aligned in the X direction.

[0076] The changeover switch 42 constitutes the changeover switch 10 in the power conversion circuit 4. The changeover switch 42 is formed by forming a switching element on a semiconductor substrate. The illustrated changeover switch 42 has a configuration similar to that of the semiconductor element 41. The changeover switch 42 is formed by forming a MOSFET on the semiconductor substrate. A parasitic diode is connected in anti-parallel to the MOSFET. The changeover switch 42 provides the above-mentioned MOSFET 10S and diode 10D.

[0077] The substrate 43 may also be referred to as a wiring board, a printed circuit board, or the like. Electronic components such as a semiconductor device 41 and a selector switch 42 are mounted on the substrate 43. The substrate 43 has, for example, a substantially rectangular planar shape. The power conversion device 20 may include a single substrate 43 or multiple substrates 43. The substrate 43 includes an insulating substrate and conductors disposed on the insulating substrate. The conductors may be disposed on only one surface of the insulating substrate, or on both the one surface and the back surface. The back surface of the insulating substrate is the surface facing the base 31 in the Z direction. The conductors may be disposed inside the insulating substrate. In other words, the substrate 43 may be a single-sided substrate, a double-sided substrate, or a multilayer substrate with three or more layers including inner layer wiring. The conductors may include via conductors. The via conductors are formed by disposing conductors, such as plating, in through holes (vias) formed in insulating layers constituting the insulating substrate. The via conductors electrically connect conductors disposed on different layers.

[0078] The illustrated substrate 43 has conductors arranged on one side and the back side of an insulating base material. The conductors arranged on the one side are patterned and form a circuit together with mounted electronic components. The patterned conductors provide a wiring function. A semiconductor element 41 is arranged on the conductor on the one side. The conductors arranged on the back side function as a heat sink.

[0079] The wiring member 44 provides a wiring function together with the patterned conductor. The wiring member 44 electrically connects, for example, an electronic component and a conductor. The wiring member 44 may electrically connect conductors to each other, or may electrically connect electronic components to each other. The wiring member 44 may also electrically connect a conductor to an external connection terminal. The wiring member 44 is, for example, a metal plate material with good conductivity, such as Cu. The wiring member 44 may also be a bonding wire. In the example shown in FIG. 6 , the source electrode of the semiconductor element 41 is electrically connected to the conductor by the metal plate material that is the wiring member 44.

[0080] The encapsulant 45 is disposed on one surface of the insulating substrate so as to cover the electronic components and the patterned conductors. The encapsulant 45 encapsulates the semiconductor element 41, the selector switch 42, and other electronic components, the wiring member 44, and the conductors. The encapsulant 45 may be a resin molded body, or may be configured to include a frame (housing) (not shown) disposed along the edge of one surface of the substrate 43, with resin or gel filled within the frame. The encapsulant 45, together with the substrate 43 and the electronic components mounted on the substrate 43, forms the main body of the semiconductor module 40. The encapsulant 45 forms at least a portion of the outer casing of the main body.

[0081] The external connection terminals include an N terminal 46N and a P terminal 46P which are power supply terminals, an output terminal 47, and a signal terminal 48. The N terminal 46N, the P terminal 46P, and the output terminal 47 are external connection terminals electrically connected to main electrodes of the semiconductor element 41, and may be referred to as main terminals or the like.

[0082] The N-terminal 46N is electrically connected to the source electrode of the semiconductor element 411L. The P-terminal 46P is electrically connected to the drain electrode of the semiconductor element 411H. The N-terminal 46N may be referred to as a low-potential power supply terminal, a negative terminal, etc. The P-terminal 46P may be referred to as a high-potential power supply terminal, a positive terminal, etc. The N-terminal 46N and the P-terminal 46P protrude to the outside from a common side surface of the main body. The N-terminal 46N and the P-terminal 46P protrude to the outside from a side surface facing the capacitor 50 in the Y-direction. The protruding portions of the N-terminal 46N and the P-terminal 46P are aligned in the X-direction.

[0083] In the illustrated semiconductor module 40, the N-terminal 46N and the P-terminal 46P protrude from the side surface of the sealing body 45 facing the capacitor 50. The semiconductor module 40 has two sets of the N-terminal 46N and the P-terminal 46P. One set of the N-terminal 46N and the P-terminal 46P is disposed on the semiconductor elements 411H and 411L side in the X direction, and the other set is disposed on the semiconductor elements 412H and 412L side in the X direction.

[0084] The semiconductor module 40 includes output terminals 47 corresponding to the U, V, and W phases of the inverter 8 and output terminals 47 corresponding to the U, V, and W phases of the inverter 9. The output terminal 47 corresponding to the inverter 8 is electrically connected to the connection point between the source electrode of the semiconductor element 411H and the drain electrode of the semiconductor element 411L, i.e., the connection point (midpoint) of the upper and lower arm circuit 8HL. The output terminal 47 corresponding to the inverter 9 is electrically connected to the connection point between the source electrode of the semiconductor element 412H and the drain electrode of the semiconductor element 412L, i.e., the connection point (midpoint) of the upper and lower arm circuit 9HL. The output terminal 47 protrudes to the outside from the side of the main body opposite to the side from which the N-terminal 46N and the P-terminal 46P protrude.

[0085] In the illustrated semiconductor module 40, the output terminal 47 protrudes to the outside from the side surface of the sealing body 45 opposite to the side surface from which the N terminal 46N and the P terminal 46P protrude. The output terminal 47 protrudes to the outside from the side surface of the sealing body 45 opposite to the surface facing the capacitor 50. The output terminal 47 may also be referred to as an O terminal, an AC terminal, etc.

[0086] The signal terminals 48 are external connection terminals electrically connected to pads of the semiconductor element 41. The signal terminals 48 protrude externally from the main body. For example, the signal terminals 48 connected to the pads of the semiconductor elements 411H and 412H protrude from the side surface common to the N-terminal 46N and the P-terminal 46P. The signal terminals 48 connected to the pads of the semiconductor elements 411L and 412L protrude from the side surface common to the output terminal 47. The protruding portions of the signal terminals 48 have bent portions and extend upward.

[0087] In the illustrated semiconductor module 40, the signal terminals 48 connected to the pads of the semiconductor elements 411H and 412H protrude to the outside from the side surface of the sealing body 45 from which the N-terminal 46N and the P-terminal 46P protrude. The signal terminals 48 connected to the pads of the semiconductor elements 411L and 412L protrude to the outside from the side surface of the sealing body 45 from which the output terminal 47 protrudes.

[0088] The semiconductor module 40 described above is disposed on the module mounting portion 3111 of the base 31. The semiconductor module 40 may be fixed to the base 31 (housing 30) by, for example, joining a conductor disposed on the back side of the substrate 43 to the base 31. The semiconductor module 40 may be fixed to the base 31 (housing 30) by screw fastening or the like, with a TIM interposed between the semiconductor module 40 and the base 31. TIM is an abbreviation for Thermal Interface Material. A large portion of the semiconductor module 40 is disposed so as to overlap the module flow path portion 344 in a plan view.

[0089] Although an example has been shown in which the semiconductor module 40 includes the substrate 43, this is not limiting. A configuration without the substrate 43 is also possible. A lead frame may be used instead of the substrate 43. Although an example has been shown in which the semiconductor module 40 includes the sealing body 45, this is not limiting. A configuration without the sealing body 45 is also possible.

[0090] <Capacitor> The capacitor 50 serves as the smoothing capacitor 7 of the power conversion circuit 4. The capacitor 50 may also be referred to as a capacitor component, a capacitor device, or the like. The capacitor 50 includes a case 51, a capacitor element 52, a sealing resin body 53, a capacitor bus bar 54, and a DC terminal portion 55. The illustrated capacitor 50 has a generally rectangular shape in plan view with the X direction as the longitudinal direction. The capacitors 50 are arranged side by side in the Y direction relative to the semiconductor module 40.

[0091] The case 51 may be formed using a metal material such as aluminum, or may be formed using a resin material. The case 51 has a cylindrical shape with a bottom. The illustrated case 51 is made of metal. The capacitor element 52 is housed in the case 51. The illustrated capacitor element 52 is a film capacitor element. The capacitor element 52 is formed, for example, by winding a film around the Z direction as an axis. The capacitor element 52 has electrodes (not shown) on both end surfaces in the Z direction. As an example, the negative electrode is provided on the upper surface, and the positive electrode is provided on the lower surface.

[0092] The sealing resin body 53 is made of an electrically insulating resin material such as epoxy resin. The sealing resin body 53 fills the case 51 and seals the capacitor element 52. The sealing resin body 53 seals a part of the capacitor bus bar 54, including the connection portion with the capacitor element 52.

[0093] The capacitor bus bar 54 is a plate made of a metal with good conductivity, such as Cu. The capacitor bus bar 54 is connected to the corresponding electrodes of the capacitor elements 52 by, for example, soldering, resistance welding, or laser welding. The capacitor bus bar 54 protrudes from one surface of the sealing resin body 53 to the outside of the sealing resin body 53. The protruding portion of the capacitor bus bar 54 is a terminal portion that electrically connects the capacitor 50 to the semiconductor module 40.

[0094] The capacitor bus bars 54 include an N bus bar 54N connected to the negative electrode and a P bus bar 54P connected to the positive electrode. The protruding portion of the N bus bar 54N crosses the top end surface of the case 51 in the Y direction and extends toward the semiconductor module 40. The protruding portion of the N bus bar 54N is joined to the N terminal 46N. Similarly, the protruding portion of the P bus bar 54P crosses the top end surface of the case 51 in the Y direction and extends toward the semiconductor module 40. The protruding portion of the P bus bar 54P is joined to the P terminal 46P.

[0095] The protruding portions of the N bus bar 54N and the P bus bar 54P have their plate surfaces facing each other over most of their extension direction to reduce inductance. The protruding portions of the N bus bar 54N and the P bus bar 54P run parallel to each other. An insulator (not shown) may be interposed between the protruding portions of the N bus bar 54N and the P bus bar 54P.

[0096] The DC terminal portion 55 is a terminal portion for electrically connecting the capacitor 50 to a DC power supply (DC power supply 2). The DC terminal portion 55 is connected to the capacitor bus bar 54. The DC terminal portion 55 includes an N-terminal portion 55N electrically connected to the negative electrode of the DC power supply, and a P-terminal portion 55P. The N-terminal portion 55N is electrically connected to the negative electrode of the DC power supply. The P-terminal portion 55P is electrically connected to the positive electrode of the DC power supply. The N-terminal portion 55N is connected to the N-bus bar 54N. The P-terminal portion 55P is connected to the P-bus bar 54P. The DC terminal portion 55 may be connected to the capacitor bus bar 54 inside the sealing resin body 53, or may be connected to the capacitor bus bar 54 outside the sealing resin body 53.

[0097] The capacitor 50 described above is disposed on the capacitor mounting portion 3112 of the base 31. The capacitor 50 may be fixed to the base 31 (housing 30) by joining the lower surface of the case 51, i.e., the lower surface 501 of the capacitor 50, to the base 31. The capacitor 50 may be fixed to the base 31 (housing 30) by screw fastening or the like, with a TIM interposed between the capacitor 50 and the base 31. Most of the capacitor 50 is disposed so as to overlap the capacitor flow path portion 345 in a plan view.

[0098] The upper end surface of the case 51 forms the upper surface 502 of the capacitor 50. The lower surface 501 forms the lower surface of the capacitor body, which includes the case 51, the capacitor element 52, and the sealing resin body 53. The upper surface 502 forms the upper surface of the capacitor body. The distance from the center of the semiconductor module 40 in the Z direction is longer for the lower surface 501 than for the upper surface 502. In other words, the semiconductor module 40 is biased toward the upper surface 502.

[0099] Although an example has been shown in which the capacitor bus bar 54 is joined to the N terminal 46N and the P terminal 46P, which are power supply terminals, the present invention is not limited to this. Bus bars connecting the capacitor bus bar 54 and the power supply terminals may be provided separately from the capacitor bus bar 54.

[0100] <Terminal Block> The terminal block 60 electrically connects an external device to elements of the power conversion device 20 (power conversion circuit 4). The terminal block 60 is fixed to the housing 30, for example, the base 31. The terminal block 60 includes an input terminal block 61 and an output terminal block 62. The input terminal block 61 electrically connects the capacitor 50 to a DC device (not shown). The output terminal block 62 electrically connects the semiconductor module 40, i.e., the inverters 8 and 9, to a rotating electric machine (not shown). The terminal block 60 has a bus bar 63 and a holding member that holds the bus bar 63. The bus bar 63 is a plate material made of a metal with good conductivity, such as Cu. The bus bar 63 may be a single plate material, or may be made by connecting multiple plates.

[0101] The input terminal block 61 has an N bus bar 631 and a P bus bar 632 as bus bars 63. The N bus bar 631 constitutes at least a portion of the above-mentioned power line 6. The P bus bar 632 constitutes at least a portion of the power line 5. The illustrated N bus bar 631 and P bus bar 632 run parallel to each other at least in part. The N bus bar 631 is electrically connected to the N terminal portion 55N of the capacitor 50 in the housing space 301 of the housing 30. The P bus bar 632 is electrically connected to the P terminal portion 55P of the capacitor 50 in the housing space 301.

[0102] The illustrated input terminal block 61 is aligned with the capacitor 50 in the X direction. The N bus bar 631 and the P bus bar 632 extend in the X direction. The N bus bar 631 and the P bus bar 632 are electrically connected to a DC power supply through openings (not shown) provided in the side wall 32 (first side wall portion 321).

[0103] The output terminal block 62 has output bus bars 633 as the bus bars 63. The output bus bars 633 include bus bars for three phases for the inverter 8 and bus bars for three phases for the inverter 9. The output bus bars 633 provide at least some of the output lines 11 and 12. The output bus bars 633 are electrically connected to corresponding output terminals 47 in the accommodation space 301 of the housing 30.

[0104] The illustrated output terminal block 62 is aligned with the semiconductor module 40 in the Y direction. In the Y direction, the semiconductor module 40 is located between the output terminal block 62 and the capacitor 50. The output bus bar 633 is substantially L-shaped in the YZ plane. One end of the output bus bar 633 extends from the holding member in the Y direction and is connected to the corresponding output terminal 47. The other end of the output bus bar 633 extends from the holding member in the Z direction, and its tip is located above the opening of the housing 30.

[0105] <Circuit Board> Although not shown, the circuit boards 70, 71, and 72 each include a substrate formed by arranging conductors including a wiring layer on an insulating base material such as resin, electronic components mounted on the substrate, connectors, etc. The mounted electronic components and conductors form a circuit. The circuit board 70 includes the drive circuit unit 132 described above. The circuit board 71 includes the drive command generation unit 131.

[0106] The circuit board 70 is arranged so as to overlap the semiconductor module 40 in a plan view. The circuit board 70 is arranged above the semiconductor module 40. The signal terminals 48 of the semiconductor module 40 are mounted on the circuit board 70. The circuit board 71 is arranged so as to overlap the semiconductor module 40, the capacitor 50, and the circuit board 70 in a plan view. The circuit board 71 is arranged above the circuit board 70. The circuit board 71 is arranged above the capacitor 50. The circuit boards 70 and 71 are arranged in the accommodation space 301.

[0107] The circuit board 72 is disposed in the accommodation space 302. The filter circuit 14 is configured on the circuit board 72. Electronic components such as coils and capacitors are mounted on the substrate that configures the circuit board 72. At least a portion of the circuit board 72 is disposed in the accommodation area 302S. The circuit board 72 is located below the module directly below portion 3121. A portion of the circuit board 72 is disposed so as to overlap with the module flow path portion 344 in a plan view.

[0108] Summary of First Embodiment The power conversion device 20 of this embodiment includes a base 31, a semiconductor module 40, and a capacitor 50. On one surface 311 of the base 31, a module mounting portion 3111 is located higher than a capacitor mounting portion 3112. A flow path 34 through which a refrigerant 35 flows is formed in the base 31, and the flow path 34 has a module flow path portion 344 and a capacitor flow path portion 345. Of the wall surfaces that define the flow path 34, an upper surface 3441 of the module flow path portion 344 is located higher than an upper surface 3451 of the capacitor flow path portion 345.

[0109] In this way, since the base 31 is provided so that the module mounting portion 3111 is located higher than the capacitor mounting portion 3112, the semiconductor module 40 can be placed closer to the upper surface 502 of the capacitor 50. This shortens the length of the wiring electrically connecting the semiconductor module 40 and the capacitor 50, thereby reducing inductance. Furthermore, the flow path 34 is provided so that the upper surface 3441 of the module flow path portion 344 is located higher than the upper surface 3451 of the capacitor flow path portion 345. This not only effectively cools the capacitor 50, but also effectively cools the semiconductor module 40 placed closer to the upper surface 502 of the capacitor 50. As described above, it is possible to increase the cooling effect while reducing inductance.

[0110] As shown in the example, the distance between the semiconductor module 40 and the lower surface 501 of the capacitor 50 may be longer than the distance between the semiconductor module 40 and the upper surface 502 of the capacitor 50. By employing such a base structure, the semiconductor module 40 can be brought closer to the upper surface 502.

[0111] As shown in the example, a flow path structure may be employed in which the lower surface 3442 of the module flow path section 344 is located above the lower surface 3452 of the condenser flow path section. In addition to this flow path structure, a base structure may be employed in which the portion 3121 directly below the module on the back surface 312 has an accommodation region 302S recessed relative to the portion 3122 directly below the condenser. This reduces inductance and improves the cooling effect, and makes it possible to utilize the accommodation region 302S located below the module flow path section 344.

[0112] As illustrated, a flow path structure having a step path 346 connecting the module flow path section 344 and the capacitor flow path section 345 may be employed. In addition to this flow path structure, a base structure having a housing area 302S immediately below the module flow path section 344 and adjacent to the step path 346 may be employed. This reduces inductance and improves the cooling effect, and makes it possible to utilize the housing area 302S located immediately below the module flow path section 344.

[0113] As illustrated, a circuit board 72 (filter circuit) may be provided in the accommodation area 302S. In this manner, the filter circuit for removing noise is provided directly below, i.e., in the vicinity of, the semiconductor module 40 (inverter), thereby reducing inductance and improving the cooling effect, and effectively suppressing the effects of noise.

[0114] As illustrated, the flow path 34 provided in the base 31 may be a hollow portion that is continuous with the inlet 36 and the outlet 37. The base 31 having such a hollow flow path 34 can be obtained by molding using a core. By adopting a hollow shape, the height can be reduced compared to a configuration in which the flow path 34 opens on one surface 311 or the back surface 312. Furthermore, a cover for covering the opening of the flow path 34 is not required, which simplifies the configuration.

[0115] As illustrated, the semiconductor module 40 includes semiconductor elements 411H and 411L that constitute the inverter 8, semiconductor elements 412H and 412L that constitute the inverter 9, and a changeover switch 42. In other words, the components of the inverters 8 and 9 and the components of the changeover switch 10 are packaged (modularized). The inverter 8 corresponds to the first inverter, and the inverter 9 corresponds to the second inverter. The semiconductor elements 411H and 411L correspond to the first semiconductor element, and the semiconductor elements 412H and 412L correspond to the second semiconductor element. Because the inverter 8, inverter 9, and changeover switch 10 are connected within the module, the wiring length can be shortened, reducing inductance. Furthermore, the overall size can be reduced.

[0116] Second Embodiment This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, the inverters 8, 9 and the changeover switch 10 are configured using a single semiconductor module. Alternatively, the inverters 8, 9 and the changeover switch 10 may be configured using multiple modules. Also, in the preceding embodiment, a single smoothing capacitor 7 is provided. Alternatively, a separate smoothing capacitor may be provided for each of the inverters 8, 9.

[0117] <Power Conversion Circuit> Fig. 8 shows an example of a power conversion circuit 4. The power conversion circuit 4 shown in Fig. 8 includes smoothing capacitors 7A and 7B. As in the previous embodiment, the power conversion circuit 4 includes power lines 5 and 6, inverters 8 and 9, a selector switch 10, and a filter circuit 14.

[0118] Smoothing capacitors 7A and 7B smooth the DC voltage supplied from the DC power supply 2. Smoothing capacitor 7A is connected to the power supply line 5 and the power supply line 6 between the DC power supply 2 and the inverter 8. Smoothing capacitor 7A is connected in parallel to the inverter 8. Smoothing capacitor 7B is connected to the power supply line 5 and the power supply line 6 on the side opposite to the DC power supply 2 via the inverter 9. Smoothing capacitor 7B is connected in parallel to the inverter 9. The other configurations are the same as those described in the preceding embodiment.

[0119] <Power Conversion Device> Fig. 9 shows an example of a power conversion device 20. For convenience, bus bars and terminals are omitted from Fig. 9. In Fig. 9, a flow path 34 is indicated by a dashed line. The power conversion device 20 provides the power conversion circuit 4 shown in Fig. 8. The power conversion device 20 includes semiconductor modules 40A, 40B, capacitors 50A, 50B, an input terminal block 61, an output terminal block 62, and a switching module 80. As with the previous embodiment, the power conversion device 20 includes circuit boards 70, 71, and 72 (not shown).

[0120] The semiconductor module 40A includes semiconductor elements 411H and 411L. The semiconductor module 40A provides the inverter 8. The semiconductor module 40B includes semiconductor elements 412H and 412L. The semiconductor module 40B provides the inverter 9. In this manner, the semiconductor modules 40A and 40B are modularized on an inverter-by-inverter basis. In the illustrated power conversion device 20, the semiconductor modules 40A and 40B are arranged side by side in the X direction. Although not shown, the semiconductor modules 40A and 40B are arranged on the module mounting portion 3111 of the base 31.

[0121] The capacitors 50A and 50B have the same configuration as the capacitor 50 shown in the preceding embodiment. Each of the capacitors 50A and 50B includes a capacitor element 52 housed in a case 51. The capacitor 50A provides a smoothing capacitor 7A. The capacitor 50B provides a smoothing capacitor 7B. In the illustrated power conversion device 20, the capacitors 50A and 50B are arranged side by side in the X direction. The capacitor 50A and the semiconductor module 40A are arranged side by side in the Y direction. The capacitor 50B and the semiconductor module 40B are arranged side by side in the Y direction. Although not shown, the capacitors 50A and 50B are arranged on the capacitor mounting portion 3112 of the base 31.

[0122] The switching module 80 includes a changeover switch 81. The changeover switch 81 corresponds to the changeover switch 42 described in the preceding embodiment. The switching module 80 provides the changeover switch 10. In the illustrated power conversion device 20, the switching module 80 is disposed between the semiconductor modules 40A, 40B and the capacitors 50A, 50B in the Y direction. The switching module 80 is disposed so as to straddle the semiconductor modules 40A, 40B in the X direction.

[0123] As in the previous embodiment, the flow path 34 is provided in the base 31. The flow path 34 includes an inlet path 341, an outlet path 342, and a connecting path 343. The inlet path 341 has an inlet port 36 attached thereto. The outlet path 342 has an outlet port 37 attached thereto. The inlet path 341 and the outlet path 342 extend generally in the Y direction. The connecting path 343 extends generally in the X direction. The inlet path 341 is provided so as to overlap with the capacitor 50A and the semiconductor module 40A in a plan view. The outlet path 342 is provided so as to overlap with the capacitor 50B and the semiconductor module 40B in a plan view. The connecting path 343 is provided so as to overlap with the semiconductor modules 40A and 40B in a plan view. The flow path 34 includes a module flow path portion 344, a capacitor flow path portion 345, and a step path 346.

[0124] The structure of the housing 30 including the base 31 is the same as the structure shown in the preceding embodiment (see FIG. 6). Although not shown, the module mounting portion 3111 is located above the capacitor mounting portion 3112. The other configurations are the same as those described in the preceding embodiment.

[0125] Summary of the Second Embodiment As illustrated, various configurations described in the preceding embodiments may be employed while including the semiconductor modules 40A, 40B, the capacitors 50A, 50B, and the switching module 80. Effects equivalent to those of the preceding embodiments can be achieved. For example, by providing the base 31 so that the module mounting portion 3111 is positioned higher than the capacitor mounting portion 3112, the semiconductor modules 40A, 40B can be positioned closer to the upper surfaces 502 of the corresponding capacitors 50A, 50B, thereby reducing inductance. Furthermore, by providing the flow path 34 so that the upper surface 3441 of the module flow path portion 344 is positioned higher than the upper surface 3451 of the capacitor flow path portion 345, not only the capacitors 50A, 50B can be effectively cooled, but also the semiconductor modules 40A, 40B positioned closer to the upper surfaces 502 of the capacitors 50A, 50B can be effectively cooled. This allows for enhanced cooling while reducing inductance.

[0126] The semiconductor module 40A corresponds to a first semiconductor module, the semiconductor module 40B corresponds to a second semiconductor module, the capacitor 50A corresponds to a first capacitor, and the capacitor 50B corresponds to a second capacitor.

[0127] Third Embodiment This embodiment is a modification of the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, the semiconductor module is held in a state where it is not in contact with the coolant 35. Alternatively, a portion of the semiconductor module may be immersed in the coolant 35.

[0128] FIG. 10 is a cross-sectional view showing an example of a power conversion device 20. FIG. 10 corresponds to FIG. 6. In the illustrated power conversion device 20, the semiconductor module 40 includes fins 49. The fins 49 are connected to the rear conductor of the substrate 43, for example, by bonding. The fins 49 are, for example, pin fins. A plurality of fins 49 are fixed to the substrate 43. The fins 49 extend in the Z direction. The fins 49 are inserted through through-holes (not shown) provided in the base 31 and are arranged in the flow path 34 (module flow path section 344). A portion of the fins 49 is immersed in the coolant 35. The periphery of the through-hole is liquid-tightly sealed with an O-ring or the like. The other configurations are similar to those described in the preceding embodiment.

[0129] Summary of Third Embodiment As illustrated, the semiconductor module 40 may be configured to include fins 49, and the fins 49 may be immersed in the coolant 35. This can further enhance the cooling effect of the semiconductor module 40.

[0130] Although the example in which the fins 49 are applied to the configuration shown in the first embodiment has been described, the present invention is not limited to this. The configuration shown in the second embodiment may be combined with the fins 49.

[0131] (Other Embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0132] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0133] When an element or layer is referred to as being "on," "coupled," "connected," or "bonded," it may be directly coupled, connected, or bonded to another element or layer, and intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly bonded" to another element or layer, no intervening elements or layers are present. Other terms used to describe relationships between elements should be construed in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used in this specification, the term "and / or" includes any and all combinations of one or more of the associated listed items. That is, a reference to A and / or B means at least one of A and B, and can include A only, B only, or both A and B.

[0134] Spatially relative terms such as "inside," "outside," "back," "below," "low," "top," "top," and the like are used herein to facilitate the description of one element or feature's relationship to other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "directly below" other elements or features would then be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may also be oriented in other ways (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0135] Although the power conversion device 20 provides the power conversion circuit 4 including the smoothing capacitors 7 (7A and 7B), the inverters 8 and 9, and the changeover switch 10, the present invention is not limited to this example. The above-described configuration can be applied to a power conversion device that provides a power conversion circuit including at least one inverter and a smoothing capacitor.

[0136] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0137] a semiconductor module (40, 40A, 40B) including a semiconductor element (41) constituting an inverter and arranged on the one surface; and a capacitor (50, 50A, 50B) arranged on the one surface and connected in parallel to the inverter, wherein in an alignment direction of the base and the capacitor, a mounting portion (3111) of the semiconductor module on the one surface is located higher than a mounting portion (3112) of the capacitor, the base has a flow path (34) through which a refrigerant flows, the flow path having a module flow path portion (344) including a portion overlapping with the semiconductor module in a plan view in the alignment direction, and a capacitor flow path portion (345) including a portion overlapping with the capacitor in the plan view, and among wall surfaces defining the flow path, an upper surface (3441) of the module flow path portion is located higher in the alignment direction than an upper surface (3451) of the capacitor flow path portion.

[0138] <Technical Concept 2> The power conversion device according to Technical Concept 1, wherein a distance between the semiconductor module and a lower surface (501) of the capacitor in the arrangement direction is longer than a distance between the semiconductor module and an upper surface (502) of the capacitor.

[0139] <Technical Idea 3> The power conversion device according to Technical Idea 1 or Technical Idea 2, wherein, of the wall surfaces, a lower surface (3442) of the module flow path portion is located higher than a lower surface (3452) of the condenser flow path portion, and the base has, on a back surface opposite to the one surface, a housing area (302S) that is recessed with respect to a portion including directly below the condenser flow path portion, in a portion including directly below the module flow path portion.

[0140] <Technical Idea 4> The power conversion device according to Technical Idea 1 or Technical Idea 2, wherein the flow path has a step path (346) connecting the module flow path portion and the capacitor flow path portion, and the base has an accommodation area (302S) immediately below the module flow path portion and adjacent to the step path.

[0141] <Technical Concept 5> The power conversion device according to Technical Concept 3 or 4, further comprising a filter circuit (72) arranged in the accommodation area and connected in parallel to the inverter.

[0142] <Technical Concept 6> The power conversion device according to any one of Technical Concepts 1 to 5, further comprising an inlet (36) for the coolant and an outlet (37) for the coolant, and the flow path is a hollow portion that communicates with the inlet and the outlet.

[0143] <Technical Idea 7> The semiconductor module is a power conversion device according to any one of Technical Ideas 1 to 6, which has, as the semiconductor elements, first semiconductor elements (411H, 411L) constituting a first inverter (8) connected to one end of a winding of a rotating electric machine (3), and second semiconductor elements (412H, 412L) constituting a second inverter (9) connected to the other end of the winding, and also has a change-over switch (42) that connects the first inverter and the second inverter without going through the winding in a closed state, and cuts off the connection between the first inverter and the second inverter in an open state.

[0144] <Technical Idea 8> The power conversion device according to any one of Technical Ideas 1 to 6, wherein the semiconductor module includes a first semiconductor module (40A) constituting a first inverter (8) connected to one end of a winding of a rotating electric machine (3) as the inverter, and a second semiconductor module (40B) constituting a second inverter (9) connected to the other end of the winding, and the capacitor includes a first capacitor (50A) connected in parallel to the first semiconductor module and a second capacitor (50B) connected in parallel to the second semiconductor module, and the power conversion device further includes a switching module (80) having a changeover switch (81) that connects the first inverter and the second inverter without passing through the winding in a closed state and cuts off the connection between the first inverter and the second inverter in an open state.

Claims

1. A power conversion device comprising: a base (31) having one surface; semiconductor modules (40, 40A, 40B) including semiconductor elements (41) constituting an inverter and arranged on the one surface; and capacitors (50, 50A, 50B) arranged on the one surface and connected in parallel to the inverter, wherein in an alignment direction of the base and the capacitors, a mounting portion (3111) for the semiconductor module on the one surface is located higher than a mounting portion (3112) for the capacitor, the base has a flow path (34) through which a refrigerant flows, the flow path having a module flow path portion (344) including a portion overlapping with the semiconductor module in a plan view in the alignment direction, and a capacitor flow path portion (345) including a portion overlapping with the capacitor in the plan view, and among wall surfaces defining the flow path, an upper surface (3441) of the module flow path portion is located higher in the alignment direction than an upper surface (3451) of the capacitor flow path portion.

2. The power conversion device according to claim 1, wherein the distance between the semiconductor module and the lower surface (501) of the capacitor in the arrangement direction is longer than the distance between the semiconductor module and the upper surface (502) of the capacitor.

3. A power conversion device as described in claim 1 or claim 2, wherein the lower surface (3442) of the module flow path section among the wall surfaces is located higher than the lower surface (3452) of the condenser flow path section, and the base has a housing area (302S) on the back surface opposite to the one surface, which includes a portion directly below the module flow path section, and which is recessed with respect to a portion including a portion directly below the condenser flow path section.

4. A power conversion device as described in claim 1 or claim 2, wherein the flow path has a step path (346) connecting the module flow path section and the capacitor flow path section, and the base has a storage area (302S) directly below the module flow path section and adjacent to the step path.

5. The power conversion device according to claim 3, further comprising a filter circuit (72) disposed in the accommodation area and connected in parallel with the inverter.

6. The power conversion device according to claim 1 or 2, further comprising an inlet (36) for the coolant and an outlet (37) for the coolant, and the flow path is a hollow portion that communicates with the inlet and the outlet.

7. The power conversion device according to claim 1 or 2, wherein the semiconductor module has, as the semiconductor elements, first semiconductor elements (411H, 411L) constituting a first inverter (8) connected to one end of a winding of a rotating electric machine (3), and second semiconductor elements (412H, 412L) constituting a second inverter (9) connected to the other end of the winding, and a change-over switch (42) which connects the first inverter and the second inverter without passing through the winding in a closed state, and which cuts off the connection between the first inverter and the second inverter in an open state.

8. The power conversion device according to claim 1 or 2, wherein the semiconductor module includes a first semiconductor module (40A) constituting a first inverter (8) connected to one end of a winding of a rotating electric machine (3) as the inverter, and a second semiconductor module (40B) constituting a second inverter (9) connected to the other end of the winding, and the capacitor includes a first capacitor (50A) connected in parallel to the first semiconductor module and a second capacitor (50B) connected in parallel to the second semiconductor module, and further comprising a switching module (80) having a change-over switch (81) that connects the first inverter and the second inverter without passing through the winding in a closed state and cuts off the connection between the first inverter and the second inverter in an open state.

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