Electric device

Abstract

A power conversion device serving as this electric device comprises: a main terminal (32P) that forms an energization path; and a P bus bar (52P) that forms an energization path together with a first bus bar. The main terminal (32P) corresponds to the first bus bar, and the P bus bar (52P) corresponds to the second bus bar. Furthermore, the electric device comprises a fastening member (80) that fastens the first bus bar and the second bus bar to each other, and a cooling member (90) that cools the heat generated by the first bus bar and the second bus bar in association with the energization. The cooling member (90) is in contact with both the first bus bar and the fastening member (80).

Description

Electrical equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-205447 filed in Japan on December 5, 2023, and Patent Application No. 2024-206656 filed in Japan on November 27, 2024, and the contents of the base applications are incorporated by reference in their entirety.

[0002] The disclosure in this specification relates to an electric device having a bus bar that forms a current path.

[0003] Patent Document 1 describes a pair of bus bars that form a current path and are fastened together with a bolt and a nut. The nut is cooled by a heat sink.

[0004] Japanese Patent Application Laid-Open No. 2008-98007

[0005] In order to cool the heat generated in the bus bar due to the passage of current, it is not sufficient to simply cool the nut, and there is room for improvement in the cooling structure described in Patent Document 1.

[0006] One disclosed object is to provide an electrical device with improved cooling performance.

[0007] In order to achieve the above object, an "electrical device" according to one aspect of the present disclosure includes: a first bus bar that forms a current path; a second bus bar that forms a current path together with the first bus bar; a fastening member that fastens the first bus bar and the second bus bar together; and a cooling member that cools heat generated in the first bus bar and the second bus bar as current flows through them, wherein the cooling member is in contact with both the first bus bar and the fastening member.

[0008] In the electric device disclosed herein, the cooling member is in contact with both the first bus bar and the fastening member, which improves cooling performance compared to a structure in which one of them is in contact and the other is not.

[0009] The reference numbers in parentheses above merely indicate an example of the correspondence with specific configurations in the embodiments described below, and do not in any way limit the technical scope.

[0010] 3 is a diagram showing a circuit configuration and a drive system in a power conversion device as an electric device according to a first embodiment. FIG. 4 is a plan view showing the power conversion device. FIG. 5 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 2 is an enlarged view of FIG. 3, showing a cross-sectional view of a bus bar cooling structure. FIG. 6 is a top view of a bolt. FIG. 7 is a cross-sectional view of a bolt before crimping. FIG. 8 is a cross-sectional view of a bolt after crimping. FIG. 9 is a cross-sectional view of a bus bar cooling structure according to a second embodiment. FIG. 10 is a cross-sectional view of a bus bar cooling structure according to a third embodiment. FIG. 11 is a cross-sectional view of a bus bar cooling structure according to a fourth embodiment. FIG. 12 is a cross-sectional view of a bus bar cooling structure according to a fifth embodiment. FIG. 13 is a cross-sectional view of a bus bar cooling structure according to a sixth embodiment. FIG. 14 is a cross-sectional view of a bus bar cooling structure according to a seventh embodiment. FIG. 15 is a diagram showing the circuit configuration of a power conversion device according to other embodiments.

[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 electric device of this embodiment is, for example, a power conversion device applied to 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, construction machinery, or agricultural machinery. An example of application to a vehicle will be described below.

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

[0014] <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 .

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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. The two high-side switching elements are connected in parallel, and the two low-side switching elements 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.

[0023] In this embodiment, n-channel MOSFETs 13 are used as the switching elements. 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).

[0024] A freewheeling diode 14 (hereinafter referred to as FWD 14) is connected in anti-parallel to each of the MOSFETs 13. In the case of the MOSFETs 13, the FWD 14 may be a parasitic diode (body diode) or an external diode. In the upper arm 10H, the drain of the MOSFET 13 is connected to the P line 8. In the lower arm 10L, the source of the MOSFET 13 is connected to the N line 9. The drain of the MOSFET 13 in the upper arm 10H and the drain of the MOSFET 13 in the lower arm 10L are connected to each other. The anode of the FWD 14 is connected to the source of the corresponding MOSFET 13, and the cathode is connected to the drain.

[0025] 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. In the case of an IGBT, the FWD 14 is also connected in anti-parallel.

[0026] 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.

[0027] 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.

[0028] <Structure of Power Converter> Fig. 2 is a plan view showing a power converter 4 of this embodiment. In Fig. 2, the circuit board is omitted so that the arrangement of the semiconductor modules and coolers can be seen. The white arrows in Fig. 2 indicate 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. Furthermore, of the external connection terminals, the portion sealed in the sealing body is omitted.

[0029] The power conversion device 4 of this embodiment includes a base 20 having a first cooler 21, semiconductor modules 30, and a second cooler 40. The power conversion device 4 may also include a capacitor 50. The power conversion device 4 may also include a circuit board 60. As an example, the power conversion device 4 of this embodiment includes a base 20 having a first cooler 21, a plurality of semiconductor modules 30, the second coolers 40, the capacitors 50, and the circuit board 60.

[0030] 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.

[0031] <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.

[0032] 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.

[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, 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. As shown in FIG. 2 , the three semiconductor modules 30 are arranged side by side in the X direction.

[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-described n-channel MOSFET 13 and FWD 14 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 of the semiconductor elements 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 the 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. 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 aligned in the X direction. The signal terminal 32S also protrudes from the side surface 31c of the main body 31.

[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 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, as an example, a thermally conductive member 70 is interposed between the semiconductor module 30 and the first cooler 21. The thermally conductive member 70 transfers heat from the semiconductor module 30, for example, heat generated by the semiconductor element 33, to the first cooler 21. The thermally conductive member 70 has electrical insulation properties. In this embodiment, as an example, the thermally conductive member 70 is thermally conductive grease. A thermally conductive gel may be used instead of thermally conductive grease.

[0045] <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 70 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.

[0046] 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. The second cooler 40 is connected to the first cooler 21 via connecting pipes 45 and 46.

[0047] 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.

[0048] <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.

[0049] As an example, the capacitor element of this embodiment is a film capacitor element. The capacitor element is formed by winding a film around an axis in the Z direction, for example. The capacitor element has electrodes (not shown) on both end surfaces in the Z direction. Capacitor 50 has P terminal 51P connected to the positive electrode and N terminal 51N connected to the negative electrode.

[0050] The P terminal 51P and the N terminal 51N are plate-shaped metal members. The P terminal 51P and the N terminal 51N are connected to the corresponding electrodes by soldering, resistance welding, laser welding, or the like. The P terminal 51P and the N terminal 51N are sometimes referred to as capacitor bus bars, etc. FIGS. 2 and 3 show the connection portions of the P terminal 51P and the N terminal 51N with the corresponding main terminals 32P, 32N. The P terminal 51P and the N terminal 51N have connection portions (not shown) for electrically connecting the smoothing capacitor 6 and the DC power supply 2.

[0051] 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.

[0052] The connection portion of the P terminal 51P and the connection portion of the N terminal 51N are drawn out toward the semiconductor module 30 in the Y direction. The connection portion of the P terminal 51P and the connection portion of the N terminal 51N are arranged so that their plate surfaces face each other to reduce inductance. The connection portion of the P terminal 51P and the connection portion of the N terminal 51N have different extension lengths in the Y direction so that they can be connected to the P bus bar 52P and the N bus bar 52N. As an example, in this embodiment, the connection portion of the N terminal 51N is located below the connection portion of the P terminal 51P. The connection portion of the N terminal 51N is longer in the Y direction than the connection portion of the P terminal 51P.

[0053] The capacitor 50 further includes a P bus bar 52P and an N bus bar 52N. The P bus bar 52P and the N bus bar 52N are plate-shaped metal members. The P bus bar 52P and the N bus bar 52N may be held in a predetermined positional relationship by, for example, an insulating member (not shown). The P bus bar 52P and the N bus bar 52N are arranged so that their plate surfaces face each other over most of their entire length to reduce inductance. The P bus bar 52P electrically connects the main terminal 32P of the semiconductor module 30 and the P terminal 51P of the capacitor 50. The N bus bar 52N electrically connects the main terminal 32N of the semiconductor module 30 and the N terminal 51N of the capacitor 50.

[0054] 4, the P bus bar 52P of this embodiment has a base 521P extending in the Z direction, and extension portions 522P and 523P extending in the Y direction from both ends of the base 521P. The extension portion 522P extends in the Y direction from the lower end of the base 521P toward the semiconductor module 30. The extension portion 522P is connected to the main terminal 32P. The extension portion 523P extends in the Y direction from the upper end of the base 521P toward the capacitor 50. The extension portion 523P is connected to the P terminal 51P.

[0055] Similarly, the N bus bar 52N has a base 521N extending in the Z direction, and extensions 522N and 523N extending in the Y direction from both ends of the base 521N. The extension 522N extends in the Y direction from the lower end of the base 521N toward the semiconductor module 30. The extension 522N is connected to the main terminal 32N. The extension 523N extends in the Y direction from the upper end of the base 521N toward the capacitor 50. The extension 523N is connected to the N terminal 51N.

[0056] The P bus bar 52P and the N bus bar 52N can be connected to the corresponding main terminals 32P, 32N and terminals 51P, 51N by soldering, resistance welding, laser welding, etc. As an example, the P bus bar 52P and the N bus bar 52N in this embodiment are connected to the corresponding P terminal 51P and N terminal 51N by laser welding.

[0057] <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.

[0058] 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.

[0059] 4 and 5 , the P bus bar 52P and the N bus bar 52N (second bus bars) and the main terminals 32P and 32N (first bus bars) are fastened to each other by fastening members 80. As a result, the P bus bar 52P and the main terminal 32P form a current path for the P line 8, and the N bus bar 52N and the main terminal 32N form a current path for the N line 9.

[0060] The fastening member 80 is configured with a bolt 81 and a nut 82. The bolt 81 and the nut 82 are made of metal. A through hole 32a is formed in the main terminals 32P, 32N, and a through hole 52a is formed in the P bus bar 52P and the N bus bar 52N. A bolt 81 is inserted into each of the through holes 32a, 52a. By tightening the inserted bolt 81 in the Z direction with the nut 82, the P bus bar 52P and the main terminal 32P are fastened to each other, and the N bus bar 52N and the main terminal 32N are also fastened to each other.

[0061] 5, the main terminals 32P, 32N are arranged below the P bus bar 52P and the N bus bar 52N. The bolt 81 is inserted from the side of the main terminals 32P, 32N. In other words, the head 812 of the bolt 81 is in close contact with the main terminals 32P, 32N, and the nut 82 is in close contact with the P bus bar 52P and the N bus bar 52N.

[0062] Next, the detailed structure of bolt 81 will be described with reference to Figures 6 and 7. Bolt 81 has a shaft portion 811, a head portion 812, an enlarged diameter portion 813, and a crimped portion 814. Shank portion 811 extends in the Z direction and is inserted into through-holes 32a and 52a, and is formed with threads that threadably engage with nut 82. Head portion 812 provides a bearing surface that is pressed against busbar bottom surface 32b, which is one surface of main terminals 32P and 32N, and comes into close contact with it.

[0063] The expanded diameter portion 813 is formed between the head portion 812 and the shaft portion 811, and has a disk shape with a larger diameter than the shaft portion 811. However, the diameter of the expanded diameter portion 813 is smaller than that of the head portion 812. The crimping portions 814 are shaped to protrude radially from the outer circumferential surface of the expanded diameter portion 813, and a plurality of the crimping portions 814 are arranged at equal intervals around the circumference of the expanded diameter portion 813.

[0064] As shown in Fig. 7 , when the bolt 81 is being inserted into the through hole 32a, that is, when the seating surface of the head 812 has not yet reached the bus bar bottom surface 32b, the crimped portion 814 is not deformed. When the bolt 81 is pushed into the through hole 32a from the state shown in Fig. 7 to the state shown in Fig. 8 , the crimped portion 814 is crushed radially between the bolt 81 and the inner wall surface of the through hole 32a. In other words, the crimped portion 814 is plastically deformed radially of the through hole 32a and crimped to the main terminal 32P. This positions the bolt 81 so that it cannot move radially relative to the main terminal 32P.

[0065] In this embodiment, even in the state shown in FIG. 8 after crimping is complete, the bolt bottom surface 812a, which is one surface of the head 812, is located below the bus bar bottom surface 32b, and the vertical positions of the bolt bottom surface 812a and the bus bar bottom surface 32b do not coincide. In other words, a part of the bolt side surface 812b, which is the side surface of the head 812, protrudes downward from the bus bar bottom surface 32b. In this way, a step is formed at the boundary between the main terminal 32P and the fastening member 80 due to the protrusion of the bolt side surface 812b.

[0066] <Busbar Cooling Structure> The main terminals 32P, 32N (first bus bars), the P bus bar 52P (second bus bar), and the N bus bar 52N (second bus bar) generate heat when current is applied. A cooling member 90 is provided to cool the heat. The cooling member 90 has a contact portion 91, an electrical insulating portion 92, and a cooling portion 93.

[0067] The cooling section 93 is a part of the base 20 that supports the semiconductor module 30. The cooling section 93 has a shape that protrudes upward from the portion of the surface 20a where the heat conduction member 70 is arranged. The cooling section 93 is cooled by the refrigerant 212, and its temperature is lower than the ambient temperature of the main terminals 32P, 32N. In other words, the cooling section 93 can also be said to be a part of the first cooler 21.

[0068] A cooling surface 93a, which is one surface of the cooling portion 93, is provided so as to overlap at least a portion of the main terminals 32P, 32N, the P bus bar 52P, and the N bus bar 52N in a plan view so as to effectively cool these bus bars. In the example shown in Figures 3 to 5, the cooling surface 93a is provided so as to encompass all of the fastening members 80 in a plan view. The cooling surface 93a extends in a plan view along the arrangement direction of the multiple (six) fastening members 80, i.e., along the X direction.

[0069] The flow paths 211 of the first cooler 21 are arranged to overlap at least a portion of the cooling surface 93a in a plan view (see FIG. 3). Furthermore, the flow paths 211 are arranged to overlap at least a portion of the main terminals 32P, 32N, the P bus bar 52P, and the N bus bar 52N in a plan view so as to effectively cool these bus bars. Furthermore, the flow paths 211 are arranged to overlap at least a portion of the fastening members 80 in a plan view. Furthermore, the flow paths 211 extend in a plan view along the arrangement direction of the multiple fastening members 80, i.e., the X direction.

[0070] The electrical insulating portion 92 is disposed between the main terminals 32P, 32N and the cooling portion 93. The electrical insulating portion 92 is made of an electrically insulating material such as resin. The electrical insulating portion 92 is sheet-shaped and has the same shape as the cooling surface 93a in plan view, i.e., a rectangle with its longitudinal axis extending in the X direction. The electrical insulating portion 92 has a main body sheet portion 92a and an extension portion 92b. The main body sheet portion 92a is shaped to cover the entire cooling surface 93a. The extension portion 92b is shaped to extend downward from the outer edge of the main body sheet portion 92a and to extend in a ring shape in plan view.

[0071] The contact portion 91 is disposed between the main terminals 32P, 32N and the electrical insulating portion 92. In other words, the electrical insulating portion 92, the contact portion 91, and the main terminals 32P, 32N are stacked in this order on the cooling surface 93a of the cooling portion 93. The lower surface of the electrical insulating portion 92 contacts the cooling surface 93a, and the upper surface of the electrical insulating portion 92 contacts the contact portion 91. The upper surface of the contact portion 91 contacts the main terminals 32P, 32N, and this contact state will be described in detail later.

[0072] Heat generated in the main terminals 32P, 32N, P bus bar 52P, and N bus bar 52N due to current flow moves to the cooling section 93 via the contact section 91 and the electrical insulating section 92. In other words, the main terminals 32P, 32N, P bus bar 52P, and N bus bar 52N are cooled by the cooling member 90. Furthermore, the cooling member 90 is in contact with the main terminals 32P, 32N and also with the fastening members 80. Therefore, the heat generated in the bus bars is cooled by the cooling member 90 via the heat conduction path via the fastening members 80.

[0073] The contact portion 91 is made of a material having a higher thermal conductivity than the electrical insulating portion 92. The electrical insulating portion 92 is made of a material having a higher electrical insulation property than the contact portion 91. The contact portion 91 is also made of a material that is softer than the electrical insulating portion 92. For example, the contact portion 91 is made of a thermally conductive grease or a thermally conductive gel similar to the thermal conductive member 70. The Z-direction dimension (thickness) of the contact portion 91 is greater than the thickness of the sheet-shaped electrical insulating portion 92.

[0074] A contact surface 91a, which is one surface of the contact portion 91, is in close contact with the busbar bottom surface 32b of the main terminals 32P, 32N. The contact surface 91a is also in close contact with the bolt 81. Specifically, the contact portion 91 is in close contact with the bolt bottom surface 812a and bolt side surface 812b of the head 812. In other words, the contact portion 91 is in close contact with the main terminals 32P, 32N and the fastening member 80 in a state where it is deformed to follow the boundary steps between the main terminals 32P, 32N and the fastening member 80.

[0075] <Y Capacitor Function> As mentioned above, the cooling unit 93 is part of the base 20, which is connected to the ground of the vehicle body or the like and is at ground potential. In other words, the cooling unit 93 is also a ground unit that is at ground potential. The cooling unit 93 as a ground unit is thermally connected to the first bus bar, the second bus bar, and the fastening member 80 while being electrically insulated by the electrical insulating unit 92. As a result, the function of the Y capacitor shown by the dashed dotted line in FIG. 1 is fulfilled. In other words, it can be said that, in effect, a P-side Y capacitor Y1 is connected between the P line 8 and ground, and an N-side Y capacitor Y2 is connected between the N line 9 and ground.

[0076] One electrode of the P-side Y capacitor Y1 is provided by the P bus bar 52P and the main terminal 32P, and the other electrode is provided by the cooling section 93. An insulating layer disposed between this pair of electrodes is provided by an electrical insulator 92. One electrode of the N-side Y capacitor Y2 is provided by the N bus bar 52N and the main terminal 32N, and the other electrode is provided by the cooling section 93. An insulating layer disposed between this pair of electrodes is provided by the electrical insulator 92, similar to the P-side Y capacitor Y1. These Y capacitors are filter capacitors that remove power supply noise from the DC power supply 2, and are also called noise absorption capacitors.

[0077] <Summary of First Embodiment> As described above, in this embodiment, the cooling member 90 is in contact not only with the main terminals 32P, 32N (first bus bars) but also with the fastening member 80, and is in contact with both the first bus bars and the fastening member 80. Therefore, a heat transfer path via the fastening member 80 is added to the heat transfer path from the first bus bars to the cooling member 90. This improves the cooling performance of the cooling member 90 for the first bus bars.

[0078] Furthermore, in this embodiment, the fastening member 80 includes a crimping portion 814 that plastically deforms in the radial direction of the through-hole 32a of the main terminals 32P, 32N and crimps to the main terminals 32P, 32N (first bus bars). If, contrary to this embodiment, the fastening member 80 were not in contact with the cooling member 90, the difference between the amount of thermal contraction of the first bus bar and the amount of thermal contraction of the fastening member 80 would be large, which could result in loosening of the crimp. In contrast, in this embodiment, the fastening member 80 is in contact with the cooling member 90, which can reduce the difference in the amount of thermal contraction described above and reduce the risk of loosening of the crimp. In other words, when the fastening member 80 includes the crimping portion 814, in addition to improving cooling performance, it also provides the effect of preventing loosening of the crimp.

[0079] Furthermore, in this embodiment, the cooling member 90 is in contact with the bolt head 812. This allows the thickness of the contact portion 91 to be thinner than when the cooling member 90 is in contact with the nut 82, shortening the heat conduction path to the cooling portion 93 and further improving cooling performance. Also, compared to when the cooling member 90 is in contact with the tip of the shaft portion 811, the contact area between the bolt 81 and the contact portion 91 can be made larger, further improving cooling performance.

[0080] Furthermore, in this embodiment, the current path formed by the main terminals 32P, 32N (first bus bars) and the P bus bar 52P and N bus bar 52N (second bus bars) is a path that conducts current between the upper and lower arm circuits 10 and the smoothing capacitor 6. The cooling unit 93 functions as a ground unit that is at ground potential, and is thermally connected to the first bus bar and the fastening member 80 while being electrically insulated from the first bus bar and the fastening member 80. This allows the cooling member 90, the fastening member 80, and the bus bars to function as a Y capacitor.

[0081] Furthermore, in this embodiment, the cooling member 90 includes a contact portion 91 that is in close contact with the first bus bar and the fastening member 80 in a state where it is deformed to conform to the boundary step between the main terminals 32P, 32N (first bus bar) and the fastening member 80. This reduces the thermal resistance between the boundary step and the cooling member 90, and further improves the cooling performance of the cooling member 90 for the first bus bar.

[0082] Furthermore, in this embodiment, the cooling portion 93 is thermally connected to the main terminals 32P, 32N (first bus bars) and the fastening member 80 via the electrical insulating portion 92 and the contact portion 91. As the electrical insulating portion 92 and the contact portion 91 are separate members, even if a crack occurs in the contact portion 91 due to thermal contraction, vibration, or the like, the electrical insulating portion 92 is not damaged and insulation may be ensured. In other words, the reliability of electrical insulation can be improved.

[0083] Second Embodiment In the first embodiment, the electrical insulating portion 92 has the extension portion 92b. In contrast, in this embodiment, as shown in Fig. 9, the electrical insulating portion 92 has two extension portions 92b and 92c. The extension portion 92b corresponds to the first extension portion, and the extension portion 92c corresponds to the second extension portion.

[0084] The extension portion 92b has the same structure as in the first embodiment and extends along the side surface 93b of the cooling portion 93. The extension portion 92c added in this embodiment extends along the side surface 91b of the contact portion 91. More specifically, the extension portion 92c extends upward from the outer edge of the main body sheet portion 92a and has a ring-shaped shape in a plan view.

[0085] As described above, in this embodiment, the side surface 93b of the cooling portion 93 is covered with the extension portion 92b (first extension portion), so the creepage distance between the first bus bar and the second bus bar and the cooling portion 93 can be increased. This improves the reliability of electrical insulation between the bus bar and the cooling portion 93. Furthermore, because the creepage distance can be increased as described above, electrical insulation can be ensured even if the thicknesses of the contact portion 91 and the electrical insulating portion 92 are reduced. Therefore, by reducing the thickness, the distance of the heat conduction path from the cooling portion 93 to the bus bar can be shortened, improving cooling performance.

[0086] Furthermore, in this embodiment, the side surface 91b of the contact portion 91 is covered with the extension portion 92c (second extension portion), which increases the creepage distance between the contact portion 91 and the cooling portion 93. This improves the reliability of electrical insulation between the contact portion 91 and the cooling portion 93. Furthermore, the provision of the extension portion 92c prevents the contact portion 91 from shifting in a direction perpendicular to the Z direction. This prevents the contact portion 91 from coming loose from between the electrical insulation portion 92 and the bus bar due to vibration or the like.

[0087] Third Embodiment In this embodiment, the contact portion 91 according to the first embodiment is used as a first contact portion, and in addition to this first contact portion, a second contact portion 910 is provided. As shown in Fig. 10 , the second contact portion 910 is disposed between the electrical insulating portion 92 and the cooling portion 93, and is in close contact with the cooling surface 93a. The electrical insulating portion 92 is disposed between the first contact portion and the second contact portion 910.

[0088] According to this embodiment, even if the flatness accuracy of the cooling surface 93 a is poor, the second contact portion 910 conducts heat by contact, thereby reducing the heat transfer resistance, thereby further improving the cooling performance of the cooling member 90 for the bus bar.

[0089] Fourth Embodiment In each of the above embodiments, the bolt 81 contacts the cooling member 90. In contrast, in this embodiment, as shown in FIG. 11 , the nut 82 contacts the cooling member 90. Specifically, the head 812 tightens both bus bars from the P bus bar 52P side, not the main terminal 32P. The nut 82 tightens both bus bars from the main terminal 32P side, not the P bus bar 52P. The nut 82 tightens both bus bars from the main terminal 32P side, not the P bus bar 52P. The nut 82 is in close contact with the contact portion 91. The contact portion 91 deforms to conform to the boundary step between the main terminals 32P, 32N (first bus bars) and the nut 82. Furthermore, the contact portion 91 deforms to conform to the boundary step between the tip of the shaft portion 811 and the nut 82. As a result, the contact portion 91 contacts not only the nut 82 but also the bolt 81. As described above, this embodiment also achieves the same effects as the first embodiment.

[0090] Fifth Embodiment In each of the above embodiments, the fastening member 80 in contact with the cooling member 90 fastens two bus bars. The two bus bars are a first bus bar and a second bus bar. In contrast, in the present embodiment, as shown in FIG. 12 , the fastening member 80 fastens three bus bars. The three bus bars are a first bus bar, a second bus bar, and a third bus bar. The current path formed by these three bus bars branches into an inverter path, a capacitor path, and a battery path from the portion fastened by the fastening member 80.

[0091] The inverter path is a current path that branches from the fastening portion with the fastening member 80 to the MOSFET 13 (semiconductor) and is provided by the main terminals 32P and 32N. The capacitor path is a current path that branches from the fastening portion with the fastening member 80 to the smoothing capacitor 6 and is provided by the P bus bar 52P and the N bus bar 52N. The battery path is a current path that branches from the fastening portion with the fastening member 80 to the DC power supply 2 (battery) and is provided by the power supply bus bar 53.

[0092] One of the pair of power supply bus bars 53 is connected to the main terminal 32P and the P bus bar 52P, and is also connected to the high potential side of the DC power supply 2. The other of the pair of power supply bus bars 53 is connected to the main terminal 32N and the N bus bar 52N, and is also connected to the low potential side of the DC power supply 2.

[0093] A through hole 53a is formed in the power supply bus bar 53. A bolt 81 is inserted into the through hole 53a. By fastening a nut 82 to the bolt 81, the high-potential side power supply bus bar 53 is fastened to the P bus bar 52P and the main terminal 32P, and the low-potential side power supply bus bar 53 is fastened to the N bus bar 52N and the main terminal 32N.

[0094] These three bus bars are stacked in the Z direction. In the example shown in Fig. 12, the power bus bar 53 contacts the head 812. The P bus bar 52P and the N bus bar 52N contact the nut 82. In other words, the main terminals 32P, 32N are arranged and clamped between the P bus bar 52P and the N bus bar 52N and the power bus bar 53. The power bus bar 53 contacts the cooling member 90 and corresponds to the first bus bar. The P bus bar 52P and the N bus bar 52N correspond to the second bus bars, and the main terminals 32P, 32N correspond to the third bus bar.

[0095] The configurations of the contact portion 91 and the electrical insulating portion 92 in this embodiment are the same as those in the above-described embodiments. In this embodiment, a contact surface 91 a, which is one surface of the contact portion 91, comes into close contact with the bus bar bottom surface 53 b of the power bus bar 53.

[0096] The direction of extension from the fastening portion of the third bus bar sandwiched in the middle is opposite to the direction of extension from the fastening portions of the first bus bar and the second bus bar. That is, the direction of extension from the fastening portion of the third bus bar is to the right in the Y direction on the paper in Fig. 12. In contrast, the directions of extension from the fastening portions of the first bus bar and the second bus bar located on both sides of the third bus bar are to the left in the Y direction on the paper in Fig. 12.

[0097] In the above-described embodiments in which the fastening member 80 fastens two bus bars, the battery path branches off from the inverter path or the capacitor path, rather than from the fastening portion. In this case, the power supply bus bar 53 may be formed integrally with another bus bar. Alternatively, the power supply bus bar 53 may be fastened to the second bus bar or the third bus bar using a fastening member other than the fastening member 80.

[0098] Here, the electrical resistance at the contact surfaces S1 and S2 between the bus bars shown in FIG. 12 is greater than the electrical resistance inside the bus bars. Therefore, the amount of heat generated in the bus bars due to current flow is greater at the contact surfaces S1 and S2 between the bus bars. In other words, the temperature at the contact surfaces S1 and S2 is more likely to rise. In particular, when three bus bars are fastened at one location as in this embodiment, the temperature at the fastened portion is more likely to rise than when two bus bars are fastened.

[0099] In consideration of this point, in this embodiment, the current path formed by the multiple bus bars to be fastened includes three paths, namely, an inverter path, a capacitor path, and a battery path. The bus bars forming each path, namely, the first bus bar, the second bus bar, and the third bus bar, are fastened at one location by a common fastening member 80. Furthermore, the cooling member 90 contacts not only the power supply bus bar 53 (first bus bar) but also the fastening member 80, and is in contact with both the first bus bar and the fastening member 80. Therefore, the effect of improving cooling performance achieved by contacting both is preferably exerted in the fastened portion, which is prone to temperature rise due to the fastening of the three bus bars.

[0100] Among the current paths, AC current mainly flows through the inverter path and the capacitor path. In contrast, DC current mainly flows through the battery path. Therefore, the amount of heat generated in the bus bars due to current flow is greater in the power supply bus bar 53 that forms the battery path than in the bus bars that form the inverter path and the capacitor path.

[0101] In consideration of this point, in this embodiment, the power supply bus bar 53 is formed separately from the other bus bars and is connected to the other bus bars by fastening members 80. Therefore, the influence of heat that the power supply bus bar 53 has on the other bus bars can be reduced compared to when the power supply bus bar 53 is formed integrally with the other bus bars without fastening.

[0102] As described above, the battery path is prone to temperature rise because DC current mainly flows through it. In other words, of the contact surfaces S1 and S2 between the bus bars, the contact surface S1 of the power bus bar 53 is prone to temperature rise more than the other contact surface S2. In consideration of this, in this embodiment, the power bus bar 53 that forms the battery path is used as the first bus bar that contacts the cooling member 90. Therefore, of the two contact surfaces S1 and S2, the contact surface S1 that is prone to temperature rise is positioned closer to the cooling member 90. This improves cooling efficiency when the fastening portions of the three bus bars are cooled by the cooling member 90.

[0103] Sixth Embodiment In the above-described fifth embodiment, the power supply bus bar 53 that forms the battery path is applied to the first bus bar that is in contact with the cooling member 90. In contrast, in the present embodiment, as shown in FIG. 13 , the bus bars that form the capacitor path, that is, the P bus bar 52P and the N bus bar 52N, are applied to the first bus bar.

[0104] In this embodiment, a contact surface 91a, which is one surface of the contact portion 91, is in close contact with the bus bar bottom surfaces 52b of the P bus bar 52P and the N bus bar 52N. The main terminals 32P and 32N are applied to the third bus bar, which is located in the middle of the two bus bars and sandwiched between them, as in the fifth embodiment. The P bus bar 52P and the N bus bar 52N are applied to the second bus bar.

[0105] Here, the smoothing capacitor 6 is also a heat-generating component that generates heat when current is applied. Excessive temperature rise in the smoothing capacitor 6 leads to performance degradation and deterioration of the smoothing capacitor 6. In consideration of this, in this embodiment, the P bus bar 52P and the N bus bar 52N that form the capacitor path are applied to the first bus bar that contacts the cooling member 90. Therefore, the P bus bar 52P and the N bus bar 52N are positioned close to the cooling member 90. Therefore, when the fastening portion of the three bus bars is cooled by the cooling member 90, it is possible to further suppress the temperature rise of the smoothing capacitor 6.

[0106] In the fifth and sixth embodiments, any bus bar related to the inverter path, the capacitor path, or the battery path can be used as the first bus bar. Any of these three types of bus bars can be used as the second bus bar. Any of these three types of bus bars can be used as the bus bar sandwiched in the middle of the three bus bars.

[0107] Seventh Embodiment In each of the above embodiments, the fastening member 80 is cooled by one cooling member 90. In contrast, in the present embodiment shown in Fig. 14, the fastening member 80 is cooled by two cooling members 90, 90x. Note that the cooling member 90 described in each of the above embodiments corresponds to the first cooling member, and the cooling member 90x added in this embodiment corresponds to the second cooling member. Furthermore, the main terminals 32P, 32N correspond to the first bus bar, and the P bus bar 52P and the N bus bar 52N correspond to the second bus bar.

[0108] Similar to the cooling member 90, the cooling member 90x has a contact portion 91x, a second contact portion 910x, an electrical insulating portion 92x, and a cooling portion 93x.

[0109] The cooling unit 93x is a part of the case 22. In this case, the cooling unit 93x is cooled by the refrigerant 212, and can also be said to be a part of the first cooler 21. Alternatively, a part of the second cooler 40 may be the cooling unit 93x. In this case, the cooling unit 93x is cooled by the refrigerant 42, and can also be said to be a part of the second cooler 40. Alternatively, a part of a cover (lid) (not shown) that closes the opening of the case 22 may be the cooling unit 93x.

[0110] A cooling surface 93ax, which is one surface of the cooling portion 93x, is provided to overlap at least a portion of the first bus bar and the second bus bar in a plan view so as to effectively cool the bus bars. In the example shown in Fig. 14, the cooling surface 93ax is provided to encompass the entire fastening member 80 in a plan view. The cooling surface 93ax and the cooling surface 93a are positioned opposite each other in the Z direction.

[0111] The electrical insulating portion 92x is disposed between the second bus bar and the cooling portion 93x. The electrical insulating portion 92x is made of the same material and has the same shape as the electrical insulating portion 92, and includes a main body sheet portion 92ax and extension portions 92bx and 92cx. The main body sheet portion 92ax is shaped to cover the entire cooling surface 93ax. The extension portion 92bx extends upward from the outer edge of the main body sheet portion 92ax and has an annular shape in plan view. The extension portion 92cx extends downward from the outer edge of the main body sheet portion 92ax and has an annular shape in plan view.

[0112] The contact portion 91x is disposed between the second bus bar and the electrical insulating portion 92x. The second contact portion 910x is disposed between the electrical insulating portion 92x and the cooling surface 93ax. In other words, the second contact portion 92x, the electrical insulating portion 92x, the contact portion 91x, and the second bus bar are stacked in this order on the cooling surface 93ax.

[0113] A portion of the heat generated in the first bus bar and the second bus bar due to the current flow is transferred to the cooling portion 93x via the contact portion 91x, the electrical insulating portion 92x, and the second contact portion 92x. That is, the first bus bar and the second bus bar are cooled by the cooling member 90x. Furthermore, the cooling member 90x is in contact with the second bus bar and also with the fastening member 80. Therefore, the heat generated in the bus bar is also cooled by the cooling member 90x through the heat transfer path via the fastening member 80. Note that the cooling effect of the cooling member 90 is the same as in the above embodiments, and according to this embodiment, the bus bar and the fastening member 80 are cooled by the two cooling members 90, 90x.

[0114] The contact portion 91x and the second contact portion 92x are made of the same material as the previously described contact portion 91. The contact portion 91x is in close contact with the bus bar upper surface 52c of the second bus bar and also with the nut 82. The contact portion 91x is also in close contact with the end surface 811a of the shaft portion 811 of the bolt 81. In other words, the contact portion 91x is in close contact with the second bus bar and the fastening member 80 in a state where it is deformed to conform to the boundary step between the nut 82 and the bolt 81.

[0115] As described above, in this embodiment, a cooling member 90x (second cooling member) is provided in addition to the first cooling member to cool the heat generated in the first bus bar and the second bus bar when current is applied. The second cooling member is in contact with both the second bus bar and the fastening member 80. In this manner, in this embodiment, the bus bar and the fastening member 80 are cooled by two cooling members 90, 90x, which improves heat dissipation compared to cooling by a single cooling member.

[0116] Furthermore, in this embodiment, one of the first cooling member and the second cooling member is in contact with the head 812 of the bolt 81. The other of the first cooling member and the second cooling member is in contact with the nut 82. Therefore, the fastening member 80 can be cooled from both axial sides of the bolt 81, and therefore the contact surfaces of the bus bars can be efficiently cooled via the fastening member 80.

[0117] The fifth or sixth embodiment may be combined with the present embodiment. That is, in a structure in which three bus bars are fastened with fastening members 80, the three bus bars may be cooled from both sides by the first cooling member and the second cooling member.

[0118] (Other Embodiments) Although multiple embodiments of the present disclosure have been described above, not only the combinations of configurations explicitly stated in the description of each embodiment but also partial combinations of configurations of multiple embodiments can be made without explicit statements, as long as there are no particular problems with the combinations. Furthermore, combinations of configurations described in multiple embodiments and modified examples that are not explicitly stated are also considered to be disclosed by the following description.

[0119] In each of the above-described embodiments, the first bus bar in contact with the cooling member 90 corresponds to the main terminals 32P and 32N, and the second bus bar corresponds to the P bus bar 52P and the N bus bar 52N. However, contrary to the present embodiment, the first bus bar may correspond to the P bus bar 52P and the N bus bar 52N, and the second bus bar may correspond to the main terminals 32P and 32N. In that case, it is desirable that the P bus bar 52P and the N bus bar 52N are located below the main terminals 32P and 32N. Furthermore, both the first bus bar and the second bus bar, together with the fastening member 80, may be in contact with the cooling member 90.

[0120] In each of the above-described embodiments, a step is formed at the boundary between the main terminal 32P and the fastening member 80 due to the protrusion of the bolt side surface 812b. However, to eliminate the step, the bolt 81 may be inserted into the busbar bottom surface 32b so that the bolt bottom surface 812a and the busbar bottom surface 32b are positioned on the same plane. In this case, the contact portion 91 comes into contact with the bolt bottom surface 812a and the busbar bottom surface 32b.

[0121] In each of the above-described embodiments, the cooling member 90 is in contact with the head 812 of the bolt 81. However, the cooling member 90 may be in contact with the tip of the shaft 811. Alternatively, the cooling member 90 may be in contact with the nut 82, or may be in contact with both the nut 82 and the bolt 81.

[0122] In each of the above-described embodiments, the nut 82 may be eliminated, and the tip of the shaft portion 811 may be welded to the P bus bar 52P or the N bus bar 52N to fix the bolt 81. Furthermore, the bolt 81 is not limited to being made of metal, but may also be made of resin. Furthermore, the bolt 81 may be a stud bolt (a stud bolt) that does not have a head portion 812.

[0123] In each of the above embodiments, the first bus bar and the second bus bar to which the bus bar cooling structure is applied are bus bars in a path that conducts current between the upper and lower arm circuits 10 and the smoothing capacitor 6. However, the first bus bar and the second bus bar may also be applied to a bus bar in a path that conducts current between the upper and lower arm circuits 10 and the motor generator 3 (motor). Even in this case, it is desirable that the cooling unit 93 be thermally connected to the first bus bar and the fastening member 80 while being electrically insulated from the first bus bar and the fastening member 80. By grounding each of the U-phase, V-phase, and W-phase windings 3a, the cooling member 90, the fastening member 80, and the bus bars function as a Y capacitor.

[0124] In this case, the function of the Y capacitor shown by the dashed line in Fig. 15 is exerted. In other words, it can be said that the Y capacitor Yu is essentially connected between the output line 11 connected to the U-phase winding 3a and ground. Similarly, it can be said that the Y capacitor Yv is connected between the output line 11 connected to the V-phase winding 3a and ground, and the Y capacitor Yw is connected between the output line 11 connected to the W-phase winding 3a and ground.

[0125] In each of the above embodiments, the cooling member 90 includes the contact portion 91 and the electrical insulating portion 92. However, the contact portion 91 may be eliminated, and the electrical insulating portion 92 may contact the bus bar bottom surface 32b. In this case, it is desirable to use a soft material for the electrical insulating portion 92 that can also contact the bolt side surface 812b. Alternatively, the electrical insulating portion 92 may be eliminated, and an electrically insulating material may be used for the contact portion 91. Furthermore, in the above second embodiment, the electrical insulating portion 92 includes the first extension portion and the second extension portion. However, either one of the extension portions or both of the extension portions may be eliminated.

[0126] In the above embodiments, the electric device is applied to a power conversion device, but it may also be applied to a converter that converts a DC voltage to a DC voltage of a different value, or to a charging device. The converter is configured, for example, with a reactor and the above-mentioned upper and lower arm circuits 10. This configuration enables voltage step-up and step-down.

[0127] (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.

[0128] (Technical Idea 1) An electrical device comprising: a first bus bar (32P, 32N) that forms a current path; a second bus bar (52P, 52N) that forms the current path together with the first bus bar; a fastening member (80) that fastens the first bus bar and the second bus bar together; and a cooling member (90) that cools heat generated in the first bus bar and the second bus bar when current is passed through the first bus bar and the second bus bar, wherein the cooling member is in contact with both the first bus bar and the fastening member.

[0129] (Technical Idea 2) The electric device according to Technical Idea 1, wherein the first bus bar has a through hole (32a) into which the fastening member is inserted, and the fastening member includes a crimping portion (814) that plastically deforms in a radial direction of the through hole and is crimped to the first bus bar.

[0130] (Technical Concept 3) The electric device according to Technical Concept 1 or 2, wherein the fastening member includes a bolt (81), and the cooling member is in contact with a head (812) of the bolt.

[0131] (Technical Idea 4) The electrical device according to any one of Technical Ideas 1 to 3, wherein the current path is a path for conducting current between the upper and lower arm circuits (10) and the smoothing capacitor (6), the cooling member includes a ground portion that is at ground potential, and the ground portion is thermally connected to the first bus bar and the fastening member while being electrically insulated from the first bus bar and the fastening member.

[0132] (Technical Idea 5) The electric device according to any one of Technical Ideas 1 to 4, wherein the cooling member includes a contact portion (91) that is in close contact with the first bus bar and the fastening member in a state where the cooling member is deformed to conform to a boundary step between the first bus bar and the fastening member.

[0133] (Technical Idea 6) The electrical device according to Technical Idea 5, wherein the cooling member includes a cooling portion (93) that is lower in temperature than the ambient temperature of the first bus bar, and an electrical insulating portion (92) that is disposed between the contact portion and the cooling portion, and the cooling portion is thermally connected to the first bus bar and the fastening member via the electrical insulating portion and the contact portion.

[0134] (Technical Idea 7) An electrical device according to Technical Idea 6, wherein the contact portion is a first contact portion, the cooling member includes a second contact portion (910) that is in close contact with the cooling portion, and the electrical insulation portion is disposed between the first contact portion and the second contact portion.

[0135] (Technical Idea 8) The electrical device according to Technical Idea 6 or 7, wherein the electrical insulation portion has at least one of a first extension portion (92b) extending along a side surface (93b) of the cooling portion and a second extension portion (92c) extending along a side surface (91b) of the contact portion.

[0136] (Technical Idea 9) An electric device according to any one of Technical Ideas 1 to 8, comprising a third bus bar (53) fastened to the first bus bar and the second bus bar by the fastening members and forming the current path together with the first bus bar and the second bus bar, wherein the current path includes an inverter path branching from a portion of the fastening members to an upper and lower arm circuit (10), a capacitor path branching from a portion of the fastening members to a smoothing capacitor (6), and a battery path branching from a portion of the fastening members to a DC power source (2), and wherein the first bus bar, the second bus bar, and the third bus bar each form one of the inverter path, the capacitor path, and the battery path.

[0137] (Technical Idea 10) The electric device according to Technical Idea 9, wherein the first bus bar forms the battery path.

[0138] (Technical Idea 11) The electric device according to Technical Idea 9, wherein the first bus bar forms the capacitor path.

[0139] (Technical Idea 12) An electric device according to any one of Technical Ideas 1 to 11, wherein the current path is a path for conducting current between the upper and lower arm circuits (10) and the motor (3), the cooling member includes a ground portion that is at ground potential, and the ground portion is thermally connected to the first bus bar and the fastening member while being electrically insulated from the first bus bar and the fastening member.

[0140] (Technical Idea 13) An electric device according to any one of Technical Ideas 1, 2, and 4 to 12, wherein the cooling member is a first cooling member, and a second cooling member (90x) is provided separately from the first cooling member to cool heat generated in the first bus bar and the second bus bar when current is applied, and the second cooling member is in contact with both the second bus bar and the fastening member.

[0141] (Technical Idea 14) The fastening member includes a bolt (81) and a nut (82), and one of the first cooling member and the second cooling member contacts a head (812) of the bolt, and the other of the first cooling member and the second cooling member contacts the nut. This is an electrical device described in Technical Idea 13.

Claims

1. An electrical device comprising: a first bus bar (32P, 32N) forming an electrical path; a second bus bar (52P, 52N) forming the electrical path together with the first bus bar; a fastening member (80) fastening the first bus bar and the second bus bar to each other; and a cooling member (90) cooling heat generated in the first bus bar and the second bus bar as electrical current flows through the first bus bar and the second bus bar, wherein the cooling member is in contact with both the first bus bar and the fastening member.

2. An electrical device as described in claim 1, wherein the first bus bar has a through hole (32a) into which the fastening member is inserted, and the fastening member includes a fastening portion (814) that plastically deforms in the radial direction of the through hole to fasten to the first bus bar.

3. An electric device as claimed in claim 1 or 2, wherein the fastening member includes a bolt (81), and the cooling member is in contact with a head (812) of the bolt.

4. The electrical device of claim 1, wherein the current path is a path for conducting current between the upper and lower arm circuits (10) and a smoothing capacitor (6), the cooling member includes a ground portion that is at ground potential, and the ground portion is thermally connected to the first bus bar and the fastening member while being electrically insulated from the first bus bar and the fastening member.

5. An electrical device as described in claim 1, wherein the cooling member includes an adhesion portion (91) that adheres to the first bus bar and the fastening member when deformed to conform to the boundary step between the first bus bar and the fastening member.

6. The electrical device described in claim 5, wherein the cooling member includes a cooling section (93) whose temperature is lower than the ambient temperature of the first bus bar, and an electrical insulating section (92) arranged between the contact section and the cooling section, and the cooling section is thermally connected to the first bus bar and the fastening member via the electrical insulating section and the contact section.

7. The electrical device of claim 6, wherein the contact portion is a first contact portion, the cooling member includes a second contact portion (910) that contacts the cooling portion, and the electrical insulation portion is disposed between the first contact portion and the second contact portion.

8. An electrical device as described in claim 6 or 7, wherein the electrical insulation portion has at least one of a first extension portion (92b) extending along a side surface (93b) of the cooling portion and a second extension portion (92c) extending along a side surface (91b) of the contact portion.

9. An electric device as described in claim 1 or 2, comprising a third bus bar (53) fastened to the first bus bar and the second bus bar by the fastening members and forming the current path together with the first bus bar and the second bus bar, wherein the current path includes an inverter path branching from the fastening member to an upper and lower arm circuit (10), a capacitor path branching from the fastening member to a smoothing capacitor (6), and a battery path branching from the fastening member to a DC power source (2), and the first bus bar, the second bus bar, and the third bus bar each form one of the inverter path, the capacitor path, and the battery path.

10. The electric device of claim 9, wherein the first bus bar forms the battery path.

11. The electric device of claim 9, wherein the first bus bar forms the capacitor path.

12. An electrical device as described in claim 1 or 2, wherein the current path is a path for conducting current between the upper and lower arm circuits (10) and the motor (3), the cooling member includes a ground portion that is at ground potential, and the ground portion is thermally connected to the first bus bar and the fastening member while being electrically insulated from the first bus bar and the fastening member.

13. An electrical device as described in claim 1 or 2, wherein the cooling member is a first cooling member, and a second cooling member (90x) is provided separately from the first cooling member for cooling heat generated in the first bus bar and the second bus bar due to current flow, and the second cooling member is in contact with both the second bus bar and the fastening member.

14. The electrical device of claim 13, wherein the fastening members include a bolt (81) and a nut (82), and one of the first cooling member and the second cooling member contacts a head (812) of the bolt, and the other of the first cooling member and the second cooling member contacts the nut.

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