Power conversion device

Abstract

This power conversion device comprises an inverter, a capacitor, and a pair of bus bars that electrically connect the inverter and the capacitor. One bus bar among the pair of bus bars has a connection part (131) electrically connected to the capacitor, and an adjacent part (113) adjacent to the connection part so as to surround the periphery of the connection part. At least a portion of the adjacent part faces the other bus bar among the pair of bus bars.

Description

Power Conversion Device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-001486 filed in Japan on January 9, 2024, the contents of which are incorporated by reference in their entirety.

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

[0003] Japanese Patent Application Laid-Open No. 2003-124222 discloses a power conversion device including a pair of bus bars that electrically connect a semiconductor device and a capacitor.

[0004] Japanese Patent Application Laid-Open No. 2020-184810

[0005] There is a demand for further suppression of parasitic inductance in the portion connecting the bus bar and the capacitor.

[0006] One disclosed object is to provide a power conversion device that suppresses parasitic inductance.

[0007] In order to achieve the above object, a "power conversion device" according to one aspect of the present disclosure includes an inverter that converts power, a capacitor that smooths power supplied from a DC power source and supplies it to the inverter, and a pair of bus bars that electrically connect the inverter and the capacitor, wherein one of the pair of bus bars has a connection portion electrically connected to the capacitor and an adjacent portion adjacent to the connection portion so as to surround the periphery of the connection portion, and at least a portion of the adjacent portion faces the other of the pair of bus bars.

[0008] In the present disclosure, one of the pair of bus bars has a connection portion that electrically connects the bus bar to the capacitor and an adjacent portion that is adjacent to the connection portion and surrounds the periphery of the connection portion. At least a portion of the adjacent portion faces the other of the pair of bus bars. This makes it possible to suppress parasitic inductance in the adjacent portion.

[0009] FIG. 1 is a diagram illustrating a circuit configuration and a drive system of a power conversion device. FIG. 2 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 3 is a cross-sectional view of a relay bus bar unit. FIG. 4 is a cross-sectional view of the relay bus bar unit and the capacitor bus bar taken along line V-V in FIG. 4. FIG. 5 is a perspective view of a relay bus bar unit. FIG. 6 is a cross-sectional view of the relay bus bar unit taken along line VII-VII in FIG. 6. FIG. 7 is a perspective view of a relay bus bar unit exploded into its constituent elements. FIG. 8 is a plan view of a capacitor bus bar. FIG. 9 is a plan view of the relay bus bar unit and the capacitor bus bar.

[0010] 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.

[0011] The electric conversion device of this embodiment is a device applied to, for example, a mobile body using a rotating electric machine as a drive source. The mobile body may be, for example, an electric vehicle such as an electric vehicle (BEV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV), an electric flying object such as a drone or an electric vertical take-off and landing (eVTOL), a ship, a construction machine, or an agricultural machine. An example of application to a vehicle will be described below.

[0012] (Embodiment) First, a schematic configuration of a vehicle drive system will be described with reference to FIG.

[0013] <Vehicle Drive System> As shown in FIG. 1 , a vehicle drive system 1 includes a DC power supply 2 , a motor generator 3 , and a power conversion device 4 .

[0014] The DC power supply 2 is a DC voltage source formed by a chargeable and dischargeable secondary battery. The motor generator 3 is a three-phase AC rotating electric machine. The motor generator 3 functions as a drive source for the vehicle, i.e., an electric motor. The motor generator 3 functions as a generator during regeneration. The power conversion device 4 converts power between the DC power supply 2 and the motor generator 3.

[0015] 1 shows the circuit configuration of a power conversion device 4. The power conversion device 4 includes at least a power conversion circuit. The power conversion circuit in this embodiment is an inverter 5. The power conversion device 4 may further include a smoothing capacitor 6, a drive circuit 7, etc.

[0016] The smoothing capacitor 6 smoothes the power supplied from the DC power supply 2 and supplies it to the inverter 5. The smoothing capacitor 6 mainly smoothes the DC voltage supplied from the DC power supply 2. The smoothing capacitor 6 is connected to a P line 8, which is a power supply line on the high potential side, and an N line 9, which is a power supply line on the low potential side. The P line 8 is connected to the positive electrode of the DC power supply 2, and the N line 9 is connected to the negative electrode of the DC power supply 2. The positive electrode of the smoothing capacitor 6 is connected to the P line 8 between the DC power supply 2 and the inverter 5. The negative electrode of the smoothing capacitor 6 is connected to the N line 9 between the DC power supply 2 and the inverter 5. The smoothing capacitor 6 is connected in parallel to the DC power supply 2.

[0017] The inverter 5 is a DC-AC conversion circuit. In accordance with switching control by a control circuit (not shown), the inverter 5 converts a DC voltage into a three-phase AC voltage and outputs it to the motor generator 3. This drives the motor generator 3 to generate a predetermined torque. During regenerative braking of the vehicle, the inverter 5 converts the three-phase AC voltage generated by the motor generator 3 in response to rotational force from the wheels into a DC voltage in accordance with switching control by the control circuit and outputs it to the P line 8. In this way, the inverter 5 performs bidirectional power conversion between the DC power source 2 and the motor generator 3.

[0018] The inverter 5 is configured with upper and lower arm circuits 10 for three phases. The upper and lower arm circuits 10 are sometimes referred to as legs. Each upper and lower arm circuit 10 has an upper arm 10H and a lower arm 10L. The upper arm 10H and the lower arm 10L are connected in series between the P line 8 and the N line 9, with the upper arm 10H on the P line 8 side.

[0019] The connection point between the upper arm 10H and the lower arm 10L, i.e., the midpoint of the upper and lower arm circuit 10, is connected to the corresponding phase winding 3a of the motor generator 3 via an output line 11. Of the upper and lower arm circuits 10, the U-phase upper and lower arm circuit 10U is connected to the U-phase winding 3a via the output line 11. The V-phase upper and lower arm circuit 10V is connected to the V-phase winding 3a via the output line 11. The W-phase upper and lower arm circuit 10W is connected to the W-phase winding 3a via the output line 11.

[0020] The upper and lower arm circuits 10 (10U, 10V, 10W) ​​each have a series circuit 12. The upper and lower arm circuits 10 may have one or more series circuits 12. When there are multiple series circuits 12, the series circuits 12 are connected in parallel to each other to form one phase of the upper and lower arm circuit 10. The series circuit 12 is formed by connecting a switching element on the upper arm 10H side and a switching element on the lower arm 10L side in series between the P line 8 and the N line 9.

[0021] The number of high-side switching elements and low-side switching elements constituting the series circuit 12 is not particularly limited. It may be one or more. The series circuit 12 of this embodiment has two switching elements on the high-side and two switching elements on the low-side. Two switching elements on the high-side are connected in parallel, and two switching elements on the low-side are connected in parallel to constitute one series circuit 12. In other words, each of the six arms 10H, 10L of the three-phase upper and lower arm circuit 10 is composed of two switching elements connected in parallel to each other.

[0022] In this embodiment, SiC-MOSFETs are used as the switching elements. Hereinafter, they will be referred to as MOSFETs 13. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. The two high-side MOSFETs 13 connected in parallel are turned on and off at the same timing by a common gate drive signal (drive voltage). The two low-side MOSFETs 13 connected in parallel are turned on and off at the same timing by a common gate drive signal (drive voltage).

[0023] The switching element is not limited to the MOSFET 13. For example, an IGBT may be used. IGBT is an abbreviation for Insulated Gate Bipolar Transistor.

[0024] The drive circuit 7 drives switching elements that constitute a power conversion circuit such as the inverter 5. The drive circuit 7 supplies a drive voltage to the gate of the corresponding MOSFET 13 based on a drive command from the control circuit. The drive circuit drives the corresponding MOSFET 13, i.e., turns it on and off, by applying the drive voltage. The drive circuit is sometimes called a driver.

[0025] The power conversion device 4 may include a control circuit for the switching elements. The control circuit generates a drive command for operating the MOSFET 13 and outputs it to the drive circuit 7. The control circuit generates the drive command based on, for example, a torque request input from a host ECU (not shown) and signals detected by various sensors. ECU is an abbreviation for Electronic Control Unit. The control circuit may be provided within the host ECU.

[0026] <Structure of power conversion device> Fig. 2 is a plan view showing the power conversion device 4 of this embodiment. In Fig. 2, the circuit board is omitted so that the arrangement of the semiconductor modules and the coolers can be seen. In Fig. 2, a portion of the relay terminal portions 136P, 136N of the relay busbar unit 100 is also omitted. The white arrow in Fig. 2 indicates the direction of refrigerant flow. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. For convenience, Fig. 3 shows only the semiconductor element and the sealing body as the main body. In addition, of the external connection terminals, the portion sealed in the sealing body is omitted.

[0027] The power conversion device 4 of the present embodiment includes a base 20 having a first cooler 21, semiconductor modules 30, a relay bus bar unit 100, and a second cooler 40. The power conversion device 4 may include a capacitor 50. The power conversion device 4 may include a circuit board 60. The power conversion device 4 may include a capacitor bus bar 51. As an example, the power conversion device 4 of the present embodiment includes a base 20 having a first cooler 21, a plurality of semiconductor modules 30, the second coolers 40, the capacitor 50, the relay bus bar unit 100, the capacitor bus bar 51, and the circuit board 60.

[0028] The relay busbar unit 100 includes a relay busbar 110 and a fixing member 120. The relay busbar 110 is a pair of busbars that electrically connect the inverter 5 and the smoothing capacitor 6. The relay busbar 110 includes a relay P busbar 110P and a relay N busbar 110N. One of the relay busbars 110 is also referred to as the relay P busbar 110P, and the other is also referred to as the relay N busbar 110N. The relay P busbar 110P and the relay N busbar 110N are plate-shaped metal members. The fixing member 120 is a member that fixes the relay P busbar 110P and the relay N busbar 110N so that they face each other with a predetermined distance d1 between them. The fixing member 120 also holds the relay P busbar 110P and the relay N busbar 110N in a predetermined positional relationship. The fixing member 120 is made of an electrically insulating resin and serves to provide electrical insulation between the relay P bus bar 110P and the relay N bus bar 110N.

[0029] In the following, the arrangement direction of the multiple semiconductor modules 30 is referred to as the X direction. The stacking direction of the first cooler 21, the semiconductor modules 30, and the second cooler 40, which is perpendicular to the X direction, is referred to as the Z direction. The direction perpendicular to both the X direction and the Z direction is referred to as the Y direction. The Y direction corresponds to one direction perpendicular to the stacking direction. The X direction, Y direction, and Z direction are in a mutually perpendicular positional relationship. A planar view from the Z direction may simply be referred to as a planar view. When describing the relative positions of two components, the position of the component closer to the base 20 in the Z direction may be referred to as the lower position, and the position of the component farther from the base 20 in the Z direction may be referred to as the upper position. First, the general configuration of each element will be described.

[0030] <Base and First Cooler> The base 20 has the semiconductor module 30 mounted on one surface 20a thereof. The base 20 is a support member that supports the semiconductor module 30. In this embodiment, as an example, the semiconductor module 30 and the capacitor 50 are arranged on one surface of the base 20. The base 20 is formed using a metal material such as aluminum.

[0031] The base 20 has a first cooler 21. The first cooler 21 is configured using the base 20. The first cooler 21 is a cooling unit in the base 20. The first cooler 21 may include a flow path through which a refrigerant flows, or may be a heat dissipation member including a heat sink or heat dissipation fins. As an example, as shown in FIGS. 2 and 3 , the first cooler 21 of this embodiment includes a flow path 211 formed inside the base 20 and a portion of the base 20 surrounding the flow path 211. A refrigerant 212 flows through the flow path 211. The refrigerant 212 may be, for example, a phase-change refrigerant such as water or ammonia, or a phase-non-change refrigerant such as an ethylene glycol-based refrigerant. The first cooler 21 cools the semiconductor module 30 from the rear surface 31b side.

[0032] The base 20 having the first cooler 21 may be formed of a single member, or may be formed by combining a plurality of members.

[0033] The base 20 may be provided as a standalone base 20, or may be provided as part of a case that houses other elements of the power conversion device 4. As an example, the base 20 in this embodiment is provided as the bottom wall of a case 22. The case 22 has an opening for accommodating other elements. The case 22 has a base 20 that forms the bottom wall, and a sidewall 23 that is connected to the base 20 and defines an accommodation space 22S together with the base 20. As an example, the case 22 in this embodiment is box-shaped with one open side. The case 22 has a substantially rectangular shape when viewed in a plane in the Z direction. The semiconductor module 30, the second cooler 40, the capacitor 50, the circuit board 60, etc. are arranged in the accommodation space 22S of the case 22.

[0034] An inlet pipe 24 for supplying the refrigerant to the first cooler 21 and the second cooler 40, and a discharge pipe 25 for discharging the refrigerant from the first cooler 21 and the second cooler 40 are attached to the side wall 23. The inlet pipe 24 and the discharge pipe 25 are attached to a common side wall 23, for example.

[0035] The power conversion device 4 may include a cover (lid) (not shown) that closes the opening of the case 22. The case 22 and the cover may be referred to as a housing.

[0036] <Semiconductor Module> The semiconductor modules 30 constitute the upper and lower arm circuits 10 described above, i.e., the inverter 5. The power conversion device 4 of this embodiment includes three semiconductor modules 30. One semiconductor module 30 provides one series circuit 12, i.e., one phase of the upper and lower arm circuits 10. The multiple semiconductor modules 30 include a semiconductor module 30U that constitutes the upper and lower arm circuit 10U, a semiconductor module 30V that constitutes the upper and lower arm circuit 10V, and a semiconductor module 30W that constitutes the upper and lower arm circuit 10W.

[0037] All of the semiconductor modules 30 have a common structure. Each semiconductor module 30 includes a main body 31 and external connection terminals 32 protruding from the main body 31. The main body 31 includes a semiconductor element 33, a sealing body 34, and the like.

[0038] As an example, the semiconductor element 33 of this embodiment is formed by forming the above-mentioned n-channel MOSFET 13 on a semiconductor substrate made of SiC. The MOSFET 13 has a vertical structure so that a main current flows in the thickness direction of the semiconductor element 33 (semiconductor substrate). The semiconductor element 33 has main electrodes on both sides of the semiconductor element 33 in the thickness direction. Specifically, each semiconductor element 33 has a drain electrode on one side and a source electrode on the back side.

[0039] A main current flows between the drain electrode and the source electrode. The semiconductor elements 33 of this embodiment include two semiconductor elements 33H that provide switching elements on the high side of the series circuit 12 and two semiconductor elements 33L that provide switching elements on the low side of the series circuit 12. The semiconductor elements 33H and 33L are arranged side by side in the Y direction. The two semiconductor elements 33H are arranged side by side in the X direction. Similarly, the two semiconductor elements 33L are arranged side by side in the X direction.

[0040] The sealing body 34 seals the semiconductor element 33, a portion of each of the external connection terminals 32, etc. Other portions of each of the external connection terminals 32 protrude outside the sealing body 34. The sealing body 34 is made of a resin such as an epoxy resin. The sealing body 34 has, for example, a substantially rectangular shape in plan view. The sealing body 34 forms the outer periphery of the main body 31.

[0041] The sealing body 34, i.e., the main body 31, has a surface 31a that forms the outer shell, and a back surface 31b that is the surface opposite to the first surface 31a in the Z direction. The first surface 31a and the back surface 31b are, for example, flat surfaces. The sealing body 34 also has side surfaces 31c and 31d that connect the first surface 31a and the back surface 31b. The side surface 31c is the surface opposite to the side surface 31d in the Y direction.

[0042] The multiple external connection terminals 32 include main terminals 32P, 32N, and 32O electrically connected to main electrodes of the semiconductor element 33, and a signal terminal 32S. The main terminal 32P is electrically connected to the drain electrode of the semiconductor element 33H. The main terminal 32N is electrically connected to the source electrode of the semiconductor element 33L. The main terminal 32P may be referred to as a P terminal, a high-potential power supply terminal, a positive terminal, etc. The main terminal 32N may be referred to as an N terminal, a low-potential power supply terminal, a negative terminal, etc. The main terminals 32P and 32N are electrically connected to the capacitor 50, i.e., the smoothing capacitor 6, via the relay P bus bar 110P and the relay N bus bar 110N. The main terminals 32P and 32N protrude externally from the side surface 31c of the main body 31. The protruding portions of the main terminals 32P and 32N are arranged side by side in the X direction.

[0043] The main terminal 32O is electrically connected to the connection point between the source electrode of the semiconductor element 33H and the drain electrode of the semiconductor element 33L, i.e., the connection point (midpoint) of the series circuit 12. The main terminal 32O protrudes to the outside from the side surface 31d of the main body 31. The main terminal 32O may also be referred to as an O terminal, an output terminal, an AC terminal, etc. The main terminal 32O is connected to the corresponding winding 3a of the motor-generator 3, for example, via a bus bar (not shown).

[0044] The signal terminal 32S protrudes from the side surface 31c of the main body 31.

[0045] The semiconductor module 30 described above is disposed on the first cooler 21 so that one surface 31a of the main body 31, i.e., the surface on which the drain electrode 33D of the semiconductor element 33 is formed, faces one surface 20a of the base 20. A thermally conductive member may be disposed between the semiconductor module 30 and the first cooler 21. In this embodiment, for example, a thermally conductive member 220 is interposed between the semiconductor module 30 and the first cooler 21. The thermally conductive member 220 transfers heat from the semiconductor module 30, such as heat generated by the semiconductor element 33, to the first cooler 21. The thermally conductive member 220 has electrical insulation properties. In this embodiment, for example, the thermally conductive member 220 is thermally conductive grease. A thermally conductive gel may be used instead of thermally conductive grease. The thermally conductive member 220 is sometimes referred to as a TIM. TIM is an abbreviation for Thermal Interface Material.

[0046] 2, the three semiconductor modules 30 are aligned in the X direction. That is, the plurality of semiconductor modules 30 are arranged side by side along the X direction.

[0047] <Second Cooler> The second cooler 40 is provided without reusing the base 20 (case 22). The second cooler 40 is disposed on the rear surface 31b of the semiconductor module 30. The second cooler 40 is stacked on the main body 31 of the semiconductor module 30 on the opposite side from the first cooler 21 so as to face the surface on which the source electrode of the semiconductor element 33 is formed. The above-mentioned thermal conductive member 220 may be disposed between the second cooler 40 and the semiconductor module 30. The second cooler 40 cools the semiconductor module 30 from the opposite side from the first cooler 21 in the Z direction. The second cooler 40 and the first cooler 21 can cool the semiconductor module 30 from both sides in the Z direction.

[0048] The second cooler 40 has a flow path 41 therein. A refrigerant 42 is supplied to the flow path 41 via an inlet pipe 24. The refrigerant 42 that has flowed through the flow path 41 is discharged to the outside of the power conversion device 4 via an outlet pipe 25. The second cooler 40 is disposed in the accommodation space 22S of the case 22. The refrigerant 42 is the same as the refrigerant 212 described above.

[0049] The second cooler 40 is connected to the first cooler 21 via connecting pipes 45 and 46 .

[0050] A portion of the refrigerant supplied from inlet pipe 24 flows through flow path 211 as refrigerant 212 and is discharged from outlet pipe 25. Another portion of the refrigerant is supplied to flow path 41 through flow path 211 and the flow path of connecting pipe 45. Refrigerant 42 that has flowed through flow path 41 flows into flow path 211 through the flow path of connecting pipe 46 and is discharged from outlet pipe 25.

[0051] <Capacitor> The capacitor 50 serves as the smoothing capacitor 6 described above. The capacitor 50 includes, for example, a case (not shown) and a capacitor element housed in the case. In Figures 2 and 3, the capacitor 50 is illustrated in a simplified form.

[0052] As an example, the capacitor element of this embodiment is a film capacitor element. The capacitor element is formed by winding a film around the Z direction as an axis. The capacitor element has electrodes (not shown) on both end surfaces in the Z direction.

[0053] The capacitor 50 has a pair of capacitor bus bars 51 electrically connected to the relay bus bar 110. The pair of capacitor bus bars 51 is composed of a capacitor P bus bar 51P and a capacitor N bus bar 51N. The capacitor P bus bar 51P and the capacitor N bus bar 51N each have first capacitor bus bar extensions 511P, 511N and second capacitor bus bar extensions 512P, 512N. The second capacitor bus bar extensions 512P, 512N are provided with capacitor bus bar connection portions 515P, 515N electrically connected to the relay bus bar 110.

[0054] Hereinafter, the capacitor bus bar 51 will be referred to as the C bus bar 51, and the capacitor P bus bar 51P and the capacitor N bus bar 51N will be referred to as the CP bus bar 51P and the CN bus bar 51N, respectively. The first capacitor bus bar extensions 511P and 511N and the second capacitor bus bar extensions 512P and 512N will be referred to as the first C extensions 511P and 511N and the second C extensions 512P and 512N, respectively. The capacitor bus bar connections will be referred to as the C connection portions 515P and 515N.

[0055] The C bus bar 51 is a plate-shaped metal member. One end of the CP bus bar 51P is connected to the positive electrode of the capacitor 50. One end of the CN bus bar 51N is connected to the negative electrode of the capacitor 50. FIG. 4 is a plan view of the relay bus bar unit, and FIG. 5 is a cross-sectional view of the relay bus bar unit and the capacitor bus bar. FIG. 5 shows a cross-sectional view of the capacitor bus bar. As shown in FIG. 5, the first C extension portions 511P, 511N extend in a predetermined first extension direction (Z direction) and have their plate surfaces facing each other. The C bus bar extension portions 511P, 511N extend in the height direction of the capacitor 50 while following the outer shape of the capacitor 50.

[0056] As shown in FIG. 9 , the second C extension portions 512P, 512N bend from the first C extension portions 511P, 511N and extend in second extension directions (Y direction) that are opposite to each other. The second C extension portions 512P, 512N bend in the second extension direction (Y direction) at the same positions in the first extension direction (Z direction). The extension direction of the second C extension portion 512N extends along the outer shape of the capacitor 50. The second C extension portion 512P extends toward the semiconductor module 30. The second C extension portion 512P is electrically connected to the relay P bus bar 110P at the C connection portion 515P. The second C extension portion 512N is electrically connected to the relay N bus bar 110N at the C connection portion 515N. The second C-extension portions 512P and 512N may extend in different directions or in the same direction, other than in opposite directions.

[0057] A capacitor insulating member 53 having electrical insulation properties is arranged between the CP bus bar 51P and the CN bus bar 51N. The capacitor insulating member 53 is a plate-shaped resin member. The capacitor insulating member 53 is arranged to ensure insulation between the CP bus bar 51P and the CN bus bar 51N. The capacitor insulating member 53 may hold the CP bus bar 51P and the CN bus bar 51N so that the CP bus bar 51P and the CN bus bar 51N are in a predetermined positional relationship. The capacitor insulating member 53 does not have to be plate-shaped, and may be insulating paper.

[0058] The capacitor 50 is disposed on one surface 20a of the base 20 that constitutes the first cooler 21. In this embodiment, the capacitor 50 is disposed in the accommodation space 22S of the case 22. The capacitor 50 is disposed side by side in the Y direction relative to the semiconductor module 30. The capacitor 50 has a generally rectangular shape in plan view with the X direction as the longitudinal direction.

[0059] <Circuit Board> Although not shown, the circuit board 60 includes a wiring board in which wiring is arranged on an insulating base material such as resin, electronic components mounted on the wiring board, connectors, etc. The mounted electronic components and wiring form a circuit. The drive circuit 7 described above is formed on the circuit board 60.

[0060] The circuit board 60 is arranged so as to overlap the semiconductor modules 30 in a plan view in the Z direction. The circuit board 60 is arranged above the three semiconductor modules 30. The signal terminals 32S of the three semiconductor modules 30 are mounted on the circuit board 60. As an example, the circuit board 60 in this embodiment is arranged in the accommodation space 22S of the case 22. The circuit board 60 is located above the second cooler 40.

[0061] <Relay Bus Bar Unit> As shown in FIGS. 5 and 7 , the relay bus bar 110 has first extension portions 111P, 111N extending in a first bus bar extension direction (Y direction), which is a predetermined direction. The first extension portions 111P, 111N are plate-shaped, and their plate surfaces face each other in the Z direction, which is the plate thickness direction. The relay bus bar 110 has second extension portions 112P, 112N. The second extension portions 112P, 112N bend from the ends of the first extension portions 111P, 111N and extend in a second bus bar extension direction (Z direction), which is a direction different from the first bus bar extension direction. The second extension portions 112P, 112N are plate-shaped, and their plate surfaces face each other in the Y direction, which is the plate thickness direction. The relay bus bar 110 has connection portions 131, 132, 133, and 134 for electrically connecting the inverter and the capacitor.

[0062] 6 and 9 , the fixing member 120 is disposed between the relay bus bars 110 so as to be sandwiched between the relay bus bars 110. The fixing member 120 is a member that fixes the relay bus bar 110. The fixing member 120 has a first extending portion 121, a second extending portion 122, a first fixing portion 123, a second fixing portion 124, a fixing member through hole 127, an annular wall 126, and a guide portion 125. As shown in FIG. 7 , the first extending portion 121 is disposed between the first extending portions 111P and 111N in the direction in which the first extending portions 111P and 111N face each other. The second extending portion 122 is disposed between the second extending portions 112P and 112N in the direction in which the second extending portions 112P and 112N face each other.

[0063] <Relay P Bus Bar> As shown in FIGS. 6 and 7 , the relay P bus bar 110P is disposed below the relay N bus bar 110N in the Z direction. The first extension portion 111P is disposed below the first extension portion 111N in the Z direction. As shown in FIG. 4 , the first extension portion 111P is disposed above the capacitor 50 and the C bus bar 51 in the Z direction. In other words, the first extension portion 111P, which is one of the bus bars, is disposed between the capacitor 50 and the first extension portion 111P, which is the other bus bar, in the direction in which the relay bus bars 110 face each other. The length of the first extension portion 111P in the Y direction is shorter than that of the first extension portion 111N. The first extension portion 111P is covered from above in the Z direction by the first extension portion 111N.

[0064] A first connection portion 131 electrically connected to the CP bus bar 51P is provided on the first extension portion 111P of the relay P bus bar 110P. One or more first connection portions 131 may be provided. As an example, two first connection portions 131 are provided spaced apart in the X direction. The first connection portions 131 are provided at the same position in the Y direction, but may also be provided at different positions. The first connection portion 131 is electrically connected to the C connection portion 515P, thereby electrically connecting the relay P bus bar 110P and the CP bus bar 51P.

[0065] The relay bus bar 110 may be electrically connected to the inverter 5 or the smoothing capacitor 6 by bolting, soldering, resistance welding, laser welding, or the like. As an example, in this embodiment, the first connection portion 131 and the CP bus bar 51P are connected by laser welding. The areas of the multiple first connection portions 131 may be equal to or different from each other. The first connection portion 131 has a rectangular shape and is elongated in the longitudinal direction (X direction) of the first extension portion 111P. The longitudinal lengths of the multiple first connection portions 131 may be equal to or different from each other.

[0066] The first extension portion 111P faces the second C extension portion 512P in the plate thickness direction (Z direction). The first extension portion 111P and the second C extension portion 512P extend parallel to each other in the same direction (Y direction). The plate surfaces of the first extension portion 111P and the second C extension portion 512P face each other. The first connection portion 131 and the C connection portion 515P are arranged to face each other.

[0067] As shown in FIG. 6 , the second extending portion 112P is provided with a relay terminal portion 136P that bends from the lower end of the second extending portion 112P in the Z direction and extends to the inverter 5. A plurality of relay terminal portions 136P are provided, and each relay terminal portion 136P is provided with a third connection portion 133 that is electrically connected to the inverter 5. The relay terminal portion 136P is disposed above the main terminal 32P in the Z direction. The relay terminal portion 136P faces the main terminal 32P in the plate thickness direction (Z direction). The relay terminal portion 136P also extends parallel to the main terminal 32P in the same direction (Y direction). The relay terminal portion 136P is disposed so as to face the main terminal 32P in the Z direction. The third connection portion 133 is electrically connected to the main terminal 32P. Here, as an example, the connection is made by laser welding.

[0068] As shown in FIG. 4 , the first extension portion 111P has an adjacent portion 113 adjacent to the first connection portion 131 so as to surround the periphery of the first connection portion 131. At least a portion of the adjacent portion 113 faces the first extension portion 111N, which is the other bus bar. The adjacent portion 113 may be any portion of the first extension portion 111P that surrounds the periphery of the first connection portion 131. The shape of the adjacent portion 113 may be arbitrary. The adjacent portion 113 may be the entire portion of the first extension portion 111P excluding the first connection portion 131. The adjacent portion 113 may also be a portion of the first extension portion 111P that is a predetermined distance (e.g., several centimeters) away from the portion along the outer edge of the first connection portion 131.

[0069] The adjacent portion 113 is a part of the first extending portion 111P. The adjacent portion 113 includes the entire outer edge of the annularly extending connection portion. In this embodiment, only a part of the adjacent portion 113 faces the first extending portion 111N. As shown in FIG. 4 , the part of the adjacent portion 113 that is on the second extending portion 112N side (the relay terminal portion 136N side) of the first connection portion 131 in the Y direction faces the first extending portion 111N. The part of the adjacent portion 113 that is adjacent to the first connection portion 131 in the X direction faces the first extending portion 111N.

[0070] As shown in Fig. 8, the second extending portion 112P is provided with a plurality of penetrating fixing holes 114P. The fixing holes 114P are provided at positions in the second extending portion 112P facing the second fixing portion 124. The plurality of fixing holes 114P are provided at the same positions as each other in the Z direction. The fixing holes 114P and the second fixing portion 124 are fixed together by crimping, press-fitting, or the like. This fixes the second extending portion 112P and the fixing member 120 together.

[0071] The first extension portion 111P of the relay P busbar 110P is provided with a plurality of DESAT terminals 135P protruding in the Z direction. The DESAT terminals 135P are used in a DESAT method, which is a method for determining whether an overcurrent is flowing through the semiconductor module 30. Normally, when an appropriate current flows through the semiconductor module 30, the collector-emitter voltage of the semiconductor element 33 reaches a saturated state and indicates a low voltage. However, when an excessive current flows through the semiconductor module 30, the voltage reaches a non-saturated state and indicates a voltage higher than the saturated state. In the DESAT method, the non-saturated voltage is detected using the DESAT terminals 135P to determine whether an excessive current is flowing through the semiconductor module 30.

[0072] <Relay N bus bar> The relay N bus bar 110N is arranged above the relay P bus bar 110P in the Z direction as shown in Figures 6 and 7. The first extension portion 111N is arranged above the first extension portion 111P in the Z direction. As shown in Figure 4, the first extension portion 111N is arranged above the capacitor 50 and the C bus bar 51 in the Z direction. In other words, the first extension portion 111N, which is the other bus bar, is arranged on the opposite side of the capacitor 50 from the first extension portion 111N, which is one bus bar, in the direction in which the relay bus bars 110 face each other.

[0073] The first extension portion 111N of the relay N bus bar 110N has a base portion 115a provided with a bus bar through hole 116 and a second connection portion 132 connected to the CN bus bar 51N. The first extension portion 111N of the relay N bus bar 110N is composed of the base portion 115a, a vertical portion 115b, and a horizontal portion 115c. The first extension portion 111N branches into two midway along its extension in the Y direction and further extends in the Y direction. The first extension portion 111N is also provided with the second connection portion 132 electrically connected to the CN bus bar 51N.

[0074] The second connection portion 132 and the base portion are located at different positions in the direction (Z direction) in which the relay bus bars 110 face each other. In the present embodiment, as an example, the base portion 115a is located higher in the Z direction than the second connection portion 132. The first extension portion 111N is bent in a crank shape from the second connection portion 132 to the base portion 115a so that the second connection portion 132 extends parallel to the C connection portion 515N.

[0075] Of the first extending portion 111N, the portion that bends from the upper end of the second extending portion 112N in the Z direction, extends in the Y direction, branches into two, and further bends in the Z direction is referred to as the base portion 115a. The portion that bends from the Y direction end of the base portion 115a and extends downward in the Z direction is referred to as the vertical portion 115b. The portion that extends from the lower end of the vertical portion 115b in the Y direction is referred to as the horizontal portion 115c. A part of the base portion 115a, the vertical portion 115b, and the horizontal portion 115c form a crank shape. The base portion 115a faces the adjacent portion 113.

[0076] The second connection portion 132 is provided on the horizontal portion 115c. One or more second connection portions 132 may be provided. As an example, two second connection portions 132 are provided spaced apart in the X direction. One second connection portion 132 is provided on each of the horizontal portions 115c of the first extension portion 111N that branches into two. The second connection portions 132 are provided at the same position in the Y direction, but may also be provided at different positions. The second connection portion 132 and the C connection portion 515P are electrically connected to each other, thereby electrically connecting the relay N bus bar 110N and the CN bus bar 51N.

[0077] As an example, in this embodiment, the second connection portions 132 and the CN bus bar 51N are connected by laser welding. The areas of the multiple second connection portions 132 may be equal to or different from each other. The second connection portions 132 are rectangular and are elongated in the longitudinal direction (X direction) of the first extension portion 111N. The longitudinal lengths of the multiple second connection portions 132 may be equal to or different from each other.

[0078] The horizontal portion 115c faces the second C-extension portion 512N in the plate thickness direction (Z direction). The horizontal portion 115c and the second C-extension portion 512N extend parallel to each other in the same direction (Y direction). The plate surfaces of the horizontal portion 115c and the second C-extension portion 512N face each other. The second connection portion 132 and the C-connection portion 515N are disposed to face each other.

[0079] The connection between the second connection portion 132 and the C connection portion 515N is stronger than the connection between the first connection portion 131 and the C connection portion 515P. As an example, the second connection portion 132 has a larger area than the first connection portion 131, thereby making the connection stronger. Alternatively, the second connection portion 132 may be longer than the first connection portion 131. Furthermore, in the case of bolt fastening, the second connection portion 132 may be a bolt with higher strength than the first connection portion 131.

[0080] As shown in FIG. 6 , the second extension portion 112N is provided with a relay terminal portion 136N that bends from the lower end of the second extension portion 112N in the Z direction and extends to the inverter 5. A plurality of relay terminal portions 136N are provided, and each relay terminal portion 136N is provided with a fourth connection portion 134 that is electrically connected to the inverter 5. Of the plurality of relay terminal portions 136N, the two central relay terminal portions 136N have a larger area than the other relay terminal portions 136N. The relay terminal portion 136N is disposed above the main terminal 32N in the Z direction. The relay terminal portion 136N faces the main terminal 32N in the plate thickness direction (Z direction). The relay terminal portion 136N extends parallel to the main terminal 32N in the same direction (Y direction). The relay terminal portion 136N is disposed to face the main terminal 32N in the Z direction. The fourth connection portion 134 is electrically connected to the main terminal 32N. Here, as an example, the connection is made by laser welding.

[0081] As shown in FIG. 4 , the first connection portion 131 overlaps with the second connection portion 132 in the longitudinal direction (X direction) of the first extension portion. In one bus bar, the relay P bus bar 110P, the region of the shortest path connecting the first connection portion 131 and the third connection portion 133 is referred to as a first region R1. In the other bus bar, the relay N bus bar 110N, the region of the shortest path connecting the second connection portion 132 and the fourth connection portion 134 is referred to as a second region R2. FIG. 10 is a plan view of the relay bus bar unit 100 and the C bus bar 51. In FIG. 10 , the relay N bus bar 110N and the CN bus bar 51N are depicted as a single unit. Similarly, the relay P bus bar 110P and the CP bus bar 51P are depicted as a single unit. As shown in FIG. 10 , the first region R1 and the second region R2 at least partially face each other.

[0082] A busbar through-hole 116 is provided through the base 115a. The busbar through-hole 116 is provided at a position facing the first connection portion 131. The busbar through-hole 116 is set to be larger than the first connection portion 131. The busbar through-hole 116 is provided so that one busbar can be electrically connected to the capacitor 50 from the side of the other busbar when the relay busbars 110 are arranged to face each other. As an example, the busbar through-hole 116 is set to have a ring-like shape, but it may have any other shape.

[0083] As shown in Fig. 8, the first extending portion 111N is provided with a plurality of penetrating fixing holes 114N. The fixing holes 114N are provided in positions facing the first fixing portion 123 on the base portion 115a of the first extending portion 111N. The plurality of fixing holes 114N are provided at the same positions as each other in the Y direction. The fixing holes 114N and the first fixing portion 123 are fixed to each other by crimping, press-fitting, or the like. This fixes the first extending portion 111N to the fixing member 120.

[0084] The first extension 111N is provided with a desaturation terminal 135N that protrudes in the Z direction. The desaturation terminal 135N is provided at the end of the base 115a, but may be provided at another position. Also, multiple desaturation terminals 135N may be provided.

[0085] <Fixing Member> The first extending portion 121 of the fixing member 120 extends in the first bus bar extending direction (Y direction). The first extending portion 121 faces the first extending portions 111P, 111N in the Z direction and extends parallel to them. The second extending portion 122 extends from an end of the first extending portion 121 in the second bus bar extending direction (Z direction). The second extending portion 122 faces the second extending portions 112P, 112N in the Y direction and extends parallel to them.

[0086] The first extending portion 121 has a plurality of first fixing portions 123. The first fixing portions 123 fix the first extending portion 111N, which is the other bus bar, so that the first extending portions 111P and 111N of the relay bus bar 110 face each other. The first fixing portions 123 are protrusions that protrude in the Z direction. The first fixing portions 123 are provided at positions facing the fixing holes 114N in the Z direction. The first fixing portions 123 are inserted into the fixing holes 114N, and the first fixing portions 123 are plastically deformed. This fixes the first extending portions 121 and the first extending portions 111N, and fixes the fixing member 120 and the relay N bus bar 110N.

[0087] The second extending portion 122 has a plurality of second fixing portions 124. The second fixing portions 124 fix the second extending portion 112P, which is one of the bus bars, so that the first extending portions 111P, 111N of the relay bus bar 110 face each other with a distance d1 between them. The second fixing portions 124 also fix the second extending portion 112P, which is one of the bus bars, so that the first extending portion 111P and the first extending portion 121 face each other with a predetermined gap d1a between them. As a result, the adjacent portion 113 and the first extending portion 121 face each other with the gap d1a between them.

[0088] The second fixing portion 124 is a protrusion that protrudes in the Y direction from the second extending portion 122. The second fixing portion 124 is provided at a position facing the fixing hole 114P in the Y direction. The second fixing portion 124 is inserted into the fixing hole 114P, and the second fixing portion 124 is plastically deformed. This fixes the second extending portion 122 and the second extending portion 112P together, and fixes the fixing member 120 and the relay P bus bar 110P together.

[0089] As shown in Fig. 7, the second extending portions 112P and 112N are fixed to each other with a predetermined distance d2 in the opposing direction (Y direction) by the second fixing portion 124. In this embodiment, the second extending portion 112P and the second extending portion 122 are designed to be in contact with each other, but they do not have to be in contact. In this embodiment, the second extending portion 112N and the second extending portion 122 do not contact each other, but they may be in contact with each other. In this embodiment, the distance d2 is approximately the same as the thickness of the second extending portion.

[0090] The fixing member 120 fixes the second extension portion 112P, which is one of the bus bars, in a state in which it is elastically deformable in the direction (Z direction) facing the first connection portion 131. Here, the direction facing the first connection portion 131 can also be interpreted as a direction perpendicular to the plate surface of the second extension portion 112P. Furthermore, the direction facing the first connection portion 131 can also be interpreted as a direction in which the relay bus bars 110 face each other.

[0091] The fixing member 120 fixes the second extending portion 112P, which is one of the bus bars, with a gap d1a between the first connecting portion 131 and the fixing member 120 in the direction facing the first connecting portion 131 (Z direction). In other words, the second extending portion 112P is fixed with the adjacent portion 113 and the first extending portion 121 facing each other with a gap d1a in the direction facing the first connecting portion 131 (Z direction). The first extending portion 111P is able to elastically deform in the Z direction by the amount of this gap d1a. The gap d1 is set to be larger than the gap d2. The gap d1 is larger than the gap d2 because of the gap d1a.

[0092] Of the relay P bus bar 110P, the second extension portion 112P is fixed to the fixing member 120, but the first extension portion 111P is not fixed to the fixing member 120. Therefore, the second extension portion 112P is in a state where it can move freely, that is, the first extension portion 111P is in a state where it is cantilevered by the second fixing portion 124. As a result, the second extension portion 112P is in a state where it can move freely in a direction facing the first connection portion 131.

[0093] A guide portion 125 is provided at the lower end in the Z direction of the second extending portion 122. The guide portion 125 extends perpendicularly from the second extending portion in the Y direction, then bends and extends in the Z direction. A plurality of guide portions 125 may be provided, but only one guide portion 125 may be provided. The guide portion 125 is provided to facilitate the work of assembling the relay N bus bar 110N and the fixing member 120. When assembling the relay N bus bar 110N and the fixing member 120, the relay N bus bar 110N is inserted into the guide portion 125 to position it. Then, the work of fixing the first fixing portion 123 to the fixing hole 114N is performed.

[0094] The first extending portion 121 has a fixing member through hole 127 penetrating the first extending portion 121 at a position facing the busbar through hole 116. In other words, the fixing member through hole 127 is disposed at a position facing the first connecting portion 131. The fixing member through hole 127 is provided so that the relay P busbar 110P can be electrically connected to the capacitor 50 from the relay N busbar 110N side via the busbar through hole 116 and the fixing member through hole 127. The fixing member through hole 127 is smaller than the busbar through hole 116. The fixing member through hole 127 is formed in an annular shape, but may have any other shape. The fixing member through hole 127 has the same shape as the busbar through hole 116, but may have a different shape. For example, the busbar through hole 116 may be elliptical, and the fixing member through hole 127 may be circular.

[0095] The first extending portion 121 is provided with an annular wall 126 extending in the Z direction from the outer edge of the fixing member through hole 127. The annular wall 126 is a wall for increasing the creepage distance between the outer edge of the bus bar through hole 116 and the first extending portion 111P, which is one of the bus bars. The annular wall 126 has an annular shape that is inserted into the bus bar through hole 116 and follows the bus bar through hole 116. The annular wall 126 may have any shape as long as it follows the bus bar through hole 116. The annular wall 126 extends above the first extending portion 111N in the Z direction.

[0096] The first extension portion 121 is provided with a fixed wall 128, which is a wall adjacent to the DESAT terminals 135N, 135P. As shown in Fig. 6, the fixed wall 128 extends in the Z direction from the first extension portion 121 and is provided adjacent to the DESAT terminals 135N, 135P. The fixed wall 128 is provided to increase the creepage distance between the DESAT terminals 135N, 135P or between the DESAT terminal 135P and the first extension portion 111N. The fixed wall 128 ensures insulation between the two.

[0097] Summary of the embodiment In the present embodiment, the electrically insulating fixing member 120 fixes the relay bus bars 110, which are a pair of bus bars, at the adjacent portion 113 with a gap d1 therebetween. This prevents the gap between the relay bus bars 110, which are a pair of bus bars, from varying, making it possible to suppress parasitic inductance in the adjacent portion 113 while ensuring insulation.

[0098] In this embodiment, the second extension portion 112P is fixed to one bus bar, and the first extension portion 111N is fixed to the other bus bar. For example, consider a case where a fixing member fixes the first extension portions 111P and 111N of a pair of bus bars so that the second extension portions 112P and 112N of the pair of bus bars face each other. In this case, because neither of the second extension portions 112P and 112N of the pair of bus bars is fixed, the distance between the second extension portions 112P and 112N becomes larger than expected, which may increase parasitic inductance. Therefore, in this embodiment, the second extension portion 112P is fixed to one bus bar, and the first extension portion 111N is fixed to the other bus bar. This prevents the distance (d1) between the first extension portions 111P and 111N and the distance (d2) between the second extension portions 112P and 112N from becoming larger than expected.

[0099] Here, consider a case where a pair of bus bars, the relay bus bar 110, is fixed by the fixing member 120, and then one of the bus bars, the relay P bus bar 110P, is connected to the CP bus bar 51P. For example, suppose that the relay P bus bar 110P, one of the bus bars, is fixed to the fixing member so as not to be elastically deformable in a direction facing the first connection portion 131. In this case, when connecting, the force applied to the relay P bus bar 110P is directly transmitted to the fixing member 120, which may cause the fixing member 120 to crack. In this embodiment, the relay P bus bar 110P, one of the bus bars, is fixed so as to be elastically deformable in a direction facing the first connection portion 131. Therefore, even if a force is applied to the relay P bus bar 110P when connecting, the fixing member 120 can be prevented from cracking.

[0100] Furthermore, in this embodiment, the relay P bus bar 110P, which is one of the bus bars, is fixed to the fixing member 120 at the first connection portion 131 with a predetermined gap d1 so as to be elastically deformable in a direction facing the first connection portion 131. The relay P bus bar 110P, which is one of the bus bars, can move freely by the amount of this predetermined gap d1. This makes it possible to prevent the fixing member 120 from cracking even if force is applied to the relay P bus bar 110P when joining the relay P bus bar 110P, which is one of the bus bars, to the C connection portion 515P.

[0101] Furthermore, in this embodiment, the pair of bus bars, the relay bus bars 110, face each other at the adjacent portion 113. The other bus bar, the relay N bus bar 110N, facing the adjacent portion 113, is provided with a bus bar through hole 116 at a position facing the first connection portion 131. This makes it possible to electrically connect the one bus bar, the relay P bus bar 110P, and the capacitor 50 at the first connection portion 131 via the bus bar through hole 116.

[0102] In this embodiment, the other bus bar, the relay N bus bar 110N, and the fixing member 120, are provided with a bus bar through hole 116 and a fixing member through hole 127 that face each other. With this, when the pair of bus bars, the relay bus bar 110 and the fixing member 120, are arranged facing each other, the relay P bus bar 110P can be electrically connected to the capacitor 50 from the relay N bus bar 110N side via both through holes. If the insulating fixing member 120 were provided with the fixing member through hole 127, there is a risk that the opposing relay bus bar 110 may be short-circuited around the fixing member through hole 127, even though the fixing member 120 is arranged between the relay bus bars 110. Therefore, as disclosed herein, by providing the fixing member 120 with an annular wall 126 that is inserted into the bus bar through hole 116, the creepage distance between the outer edge of the bus bar through hole 116 of the relay N bus bar 110N and the relay P bus bar 110P can be increased by the length of the annular wall 126. Since the annular wall 126 has an annular shape that fits the bus bar through hole 116, insulation between the relay bus bars 110 is ensured even when the fixing member through hole 127 is provided, and it is therefore possible to narrow the distance between the relay bus bars, thereby suppressing parasitic inductance.

[0103] In this embodiment, the second C extensions 512P, 512N bend from the opposing first C extensions 511P, 511N and extend in opposite directions. In the present disclosure, the second C extensions 512P, 512N, each having a C connection portion 515P, 515N, extend in opposite directions, so the second C extensions 512P, 512N do not get in the way of each other during connection. This facilitates the connection process. Furthermore, because the first C extensions 511P, 511N face each other, parasitic inductance can be suppressed.

[0104] In this embodiment, the second C extension portions 512P, 512 are bent at the same positions in the extension direction of the first C extension portions 511P, 511N. This allows the power conversion device to be more compact in the extension direction than when the first C extension portions 511P, 511N are bent at different positions in the extension direction.

[0105] In this embodiment, the first extending portion 111N has a bent crank shape so as to have a portion extending parallel to the C-connecting portion 515N. As a result, even if the busbar through hole 116 is located above the C-connecting portion 515N, the second connecting portion 132 and the C-connecting portion 515P are in contact with each other in parallel, making connection easy.

[0106] In this embodiment, the relay P bus bar 110P is disposed between the capacitor 50 and the relay N bus bar 110N in the direction in which the relay bus bars 110 face each other. Therefore, the first connection portion 131 is unlikely to be peeled off due to an external force. Conversely, the relay N bus bar 110N is disposed on the opposite side of the capacitor 50 from the relay P bus bar 110P in the direction in which the relay bus bars 110 face each other. Therefore, there is a possibility that the second connection portion 132 may be peeled off due to an external force. In this embodiment, the second connection portion 132 has a larger area than the first connection portion 131, and therefore the second connection portion 132 is more firmly connected to the capacitor 50 than the first connection portion 131. This makes it possible to prevent the second connection portion from being peeled off due to an external force.

[0107] According to this embodiment, the path of the current flowing through the relay P bus bar 110P and the path of the current flowing through the relay N bus bar 110N are at least partially opposed to each other, thereby making it possible to suppress parasitic inductance between the relay bus bars 110.

[0108] According to the present embodiment, the adjacent portion 113 faces the N-relay bus bar 110N of the relay bus bar 110. This makes it possible to suppress parasitic inductance in the adjacent portion 113.

[0109] <Modification> In the embodiment, the portion of the adjacent portion 113 on the second extending portion 112N side (the relay terminal portion 136N side) in the Y direction with respect to the first connecting portion 131 faces the first extending portion 111N. The portion of the adjacent portion 113 on the second connecting portion 132 (horizontal portion 115c) side in the Y direction with respect to the first connecting portion 131 may face the first extending portion 111N. Furthermore, both the portion of the adjacent portion 113 on the second extending portion 112N side (the relay terminal portion 136N side) and the portion on the second connecting portion 132 (horizontal portion 115c) side in the Y direction with respect to the first connecting portion 131 may face the first extending portion 111N.

[0110] In the embodiment, the relay P bus bar 110P is one bus bar and the relay N bus bar 110N is the other bus bar, but they may be interchanged as appropriate.

[0111] The fixing member 120 may be a paper-like member such as insulating paper. Furthermore, as long as electrical insulation between the relay P bus bar 110P and the relay N bus bar 110N is ensured, the fixing member 120 does not need to be provided.

[0112] The first fixing portion 123 may fix the second extending portion 112N of the other bus bar so that the first extending portions 111P, 111N of the pair of bus bars face each other. The second fixing portion 124 may fix the first extending portion 111P of one bus bar so that the second extending portions 112P, 112N of the pair of bus bars face each other.

[0113] Both the first fixing portion 123 and the second fixing portion 124 may fix the same member. For example, both the first fixing portion 123 and the second fixing portion 124 may fix the first extending portion 111N. Alternatively, both the first fixing portion 123 and the second fixing portion 124 may fix the second extending portion 112P. Alternatively, only one of the first fixing portion 123 and the second fixing portion 124 may be provided.

[0114] The fixing member 120 may fix the second extending portion 112P, which is one of the bus bars, in a state where it cannot be elastically deformed in the direction facing the first connecting portion 131.

[0115] The fixing member 120 does not need to have a gap d1a between the first connecting portion 131 and the fixing member 120 in the direction facing the first connecting portion 131.

[0116] The other bus bar, the first extension portion 111N, is provided with a bus bar through hole 116, and welding between the first extension portion 111P and the second C extension portion 512P is performed from the side of the first extension portion 111N. Alternatively, the bus bar through hole 116 may be eliminated, and the welding may be performed from the opposite side of the first extension portion 111N. Also, although the fixing member 120 has the fixing member through hole 127, it is not necessary to have it.

[0117] The number and positions of the fixing holes 114P and 114N may be arbitrary. Also, the fixing holes 114P and 114N may not be provided.

[0118] The second C-extensions 512P, 512N may be bent from the first C-extensions 511P, 511N and extend in the same direction. The second C-extensions 512P, 512N may be bent at different positions in the first extension direction (Z direction).

[0119] The second connection portion 132 and the base portion 115a may be located at the same position as each other in the direction in which the relay bus bars 110 face each other. Furthermore, the first extension portion 111N, which is the other bus bar, does not need to be bent in a crank shape from the second connection portion 132 to the base portion 115a. In this case, it is desirable that the second C extension portion 512N and the second connection portion 132 are located at the same position in the Z direction.

[0120] The first connecting portion 131 may be more firmly connected to the capacitor 50 than the second connecting portion 132. The second connecting portion 132 may have a smaller area than the first connecting portion 131. The second connecting portion 132 may be shorter in length than the first connecting portion 131. In addition, in the case of bolt fastening, the second connecting portion 132 may be a bolt with lower strength than the first connecting portion 131.

[0121] The first region does not have to face the second region.

[0122] (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.

[0123] (Technical Idea 1A) A power conversion device comprising: an inverter (5) that converts power; a capacitor (50) that smooths power supplied from a DC power source (2) and supplies it to the inverter; and a pair of bus bars (110) that electrically connect the inverter and the capacitor, wherein one bus bar (110P) of the pair of bus bars has a connection portion (131) electrically connected to the capacitor and an adjacent portion (113) that surrounds the connection portion and is adjacent to the connection portion, and at least a portion of the adjacent portion faces the other bus bar (110N) of the pair of bus bars.

[0124] (Technical Concept 2A) The power conversion device according to Technical Concept 1A, further comprising an electrically insulating fixing member (120) that fixes the pair of bus bars to face each other with a predetermined gap (d1) therebetween in the adjacent portion.

[0125] (Technical Idea 3A) The power conversion device according to Technical Idea 2A, wherein the pair of bus bars have first extension portions (111P, 111N) extending in a first bus bar extension direction that is a predetermined direction, and second extension portions (112P, 112N) bending from the first extension portions and extending in a second bus bar extension direction that is a direction different from the first bus bar extension direction, and the fixing member has: a first fixing portion (123) that fixes the first extension portion of the other bus bar so that the first extension portions of the pair of bus bars face each other; and a second fixing portion (124) that fixes the second extension portion of one of the bus bars so that the second extension portions of the pair of bus bars face each other.

[0126] (Technical Concept 4A) The power conversion device according to Technical Concept 2A or 3A, wherein the fixing member fixes the one bus bar in a state in which the fixing member is elastically deformable in a direction facing the connection portion.

[0127] (Technical Concept 5A) The power conversion device according to Technical Concept 4A, wherein the one bus bar is fixed to the fixing member with a gap (d1a) between the connection portion and the fixing member in the opposing direction.

[0128] (Technical Concept 6A) The power conversion device according to any one of Technical Concepts 1A to 5A, wherein the other bus bar is provided with a bus bar through-hole (116) that penetrates the other bus bar at a position facing the connection portion.

[0129] (Technical Idea 1B) A power conversion device comprising: an inverter (5) that converts electric power; a capacitor (50) that smooths electric power supplied from a DC power source (2) and supplies it to the inverter; a pair of bus bars (110) that are arranged opposite each other and electrically connect the inverter and the capacitor; and an insulating fixing member (120) that is arranged between the pair of bus bars and fixes the pair of bus bars, wherein one bus bar (110P) of the pair of bus bars has a connection portion (131) electrically connected to the capacitor, and the other bus bar (110N) of the pair of bus bars has a bus bar through hole (116) that passes through it at a position opposite to the connection portion, and the fixing member has a fixing member through hole (127) that passes through it at a position opposite to the bus bar through hole, and an annular wall (126) that is inserted into the bus bar through hole and has an annular shape that follows the bus bar through hole.

[0130] (Technical Idea 2B) A power conversion device according to Technical Idea 1B, wherein the capacitor has a pair of capacitor bus bars (51) electrically connected to the pair of bus bars, and the pair of capacitor bus bars have: first capacitor bus bar extension portions (511P, 511N) extending in a predetermined first extension direction and facing each other; and second capacitor bus bar extension portions (512P, 512N) bending from the first capacitor bus bar extension portions and extending in second extension directions opposite each other, and having capacitor bus bar connection portions (515P, 515N) electrically connected to the pair of bus bars.

[0131] (Technical Concept 3B) The power conversion device according to Technical Concept 2B, wherein the second capacitor bus bar extension portions are bent in the second extension direction at the same positions from the first capacitor bus bar extension portion in the first extension direction.

[0132] (Technical Idea 4B) A power conversion device according to Technical Idea 2B or 3B, wherein the connection portion is a first connection portion, the other bus bar has a second connection portion (132) connected to the capacitor bus bar connection portion and a base portion (115a) in which the bus bar through hole is provided, the second connection portion and the base portion are at different positions from each other in the direction in which the pair of bus bars face each other, and the other bus bar is bent in a crank shape from the second connection portion to the base portion so that the second connection portion extends parallel to the capacitor bus bar connection portion.

[0133] (Technical Idea 5B) A power conversion device according to Technical Idea 4B, wherein the one bus bar is arranged between the capacitor and the other bus bar in the direction in which the pair of bus bars face each other, the other bus bar is arranged on the opposite side of the one bus bar from the capacitor in the direction in which the pair of bus bars face each other, the first connection portion and the second connection portion are electrically connected to the capacitor by being welded, and the second connection portion has a larger area than the first connection portion.

[0134] (Technical Idea 6B) A power conversion device according to Technical Idea 4B or 5B, wherein the one bus bar has a third connection portion (133) electrically connected to the inverter, the other bus bar has a fourth connection portion (134) electrically connected to the inverter, a region in the one bus bar that forms the shortest path connecting the first connection portion and the third connection portion is defined as a first region (R1), and a region in the other bus bar that forms the shortest path connecting the second connection portion and the fourth connection portion is defined as a second region (R2), and at least a portion of the first region faces the second region.

[0135] (Technical Idea 7B) The power conversion device according to any one of Technical Ideas 1B to 6B, wherein the one bus bar has an adjacent portion (113) adjacent to the connection portion so as to surround the periphery of the connection portion, and at least a part of the adjacent portion faces the other bus bar.

Claims

1. A power conversion device comprising: an inverter (5) that converts power; a capacitor (50) that supplies power to the inverter while smoothing the power supplied from a DC power supply (2); and a pair of bus bars (110) that electrically connect the inverter and the capacitor. One of the pair of bus bars (110P) has a connection portion (131) electrically connected to the capacitor and an adjacent portion (113) adjacent to the connection portion so as to surround the periphery of the connection portion. At least a part of the adjacent portion faces the other bus bar (110N) of the pair of bus bars.

2. The power conversion device according to claim 1, further comprising an electrically insulating fixing member (120) that fixes the pair of bus bars to face each other with a predetermined interval (d1) in the adjacent portion.

3. The pair of bus bars has a first extending portion (111P, 111N) extending in a first bus bar extending direction which is a predetermined direction, and a second extending portion (112P, 112N) extending in a second bus bar extending direction which is different from the first bus bar extending direction after bending from the first extending portion. The fixing member has a first fixing portion (123) that fixes the first extending portion of the other bus bar so that the first extending portions of the pair of bus bars face each other, and a second fixing portion (124) that fixes the second extending portion of the one bus bar so that the second extending portions of the pair of bus bars face each other. The power conversion device according to claim 2.

4. The power conversion device according to claim 2, wherein the fixing member fixes the one bus bar in a state where it can be elastically deformed in a direction facing the connection portion.

5. The power conversion device according to claim 4, wherein the one bus bar is fixed to the fixing member with a gap (d1a) provided between the connection portion and the fixing member in the facing direction.

6. The power conversion device according to any one of claims 1 to 5, wherein a bus bar through hole (116) penetrating at a position facing the connection portion is provided in the other bus bar.

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