Power conversion device

Abstract

A busbar unit (60) has a linking busbar (61) that electrically connects a semiconductor module (40) and a capacitor (50). The linking busbar (61) has a structure that is more likely to deform under external force than a capacitor busbar (54). The capacitor busbar (54) is provided so that the angle formed by a joining surface with the linking busbar (61) is 90 degrees or more. A P current path section (80P) and an N current path section (80N) including the capacitor busbar (54) and the linking busbar (61) have: a PN parallel-running section (81) in which the P current path section (80P) and the N current path section (80N) run parallel to each other; and a same potential parallel-running section (82) that is provided to one of the P current path section (80P) and the N current path section (80N) and in which the junction part between the capacitor busbar (54) and the linking busbar (61) is folded back.

Description

Power Conversion Device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-20561 filed in Japan on February 14, 2024, the contents of which are incorporated by reference in their entirety.

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

[0003] Patent Document 1 discloses a power conversion device including a power module and a capacitor module. The capacitor module has a capacitor bus bar connected to a capacitor element and protruding from a sealing resin body that seals the capacitor element. The contents of the prior art document are incorporated by reference as an explanation of the technical elements in this specification.

[0004] JP 2023-133456 A

[0005] In the configuration of Patent Document 1, when connecting the power module and the capacitor module, stress may concentrate at the base of the protruding portion of the capacitor bus bar due to manufacturing variations and assembly variations, which may cause peeling or cracks in the sealing resin body. Peeling and cracks can lead to changes in capacitance, poor insulation, and the like. Lengthening the capacitor bus bar to alleviate stress concentration increases inductance. Further improvements are needed in power conversion devices from the above-mentioned perspectives and other perspectives not mentioned.

[0006] An object of the present disclosure is to provide a power conversion device that can reduce inductance while suppressing deterioration in the quality of a capacitor.

[0007] a power conversion device according to one aspect of the disclosure, comprising: a semiconductor module having a main body and power supply terminals protruding from the main body; a capacitor having capacitor elements, a sealing resin body that seals the capacitor elements, and a capacitor bus bar including a portion connected to the capacitor element and a portion protruding from the sealing resin body; and a bus bar unit having connecting bus bars that electrically connect the capacitor bus bar and the power supply terminals, wherein the power supply terminals include a P terminal and an N terminal, the capacitor bus bar includes a capacitor P bus bar connected to a positive electrode of the capacitor element and a capacitor N bus bar connected to a negative electrode of the capacitor element, the connecting bus bar includes a connecting P bus bar that electrically connects the capacitor P bus bar and the P terminal, and a connecting N bus bar that electrically connects the capacitor N bus bar and the N terminal, the connecting bus bar has a structure that is more easily deformed by an external force than the capacitor bus bar, and the capacitor bus bar is arranged so that the angle between the joint surface of the capacitor P bus bar with the connecting P bus bar and the joint surface of the capacitor N bus bar with the connecting N bus bar is 90 degrees or more, The P current path section including the capacitor P bus bar and the connecting P bus bar, and the N current path section including the capacitor N bus bar and the connecting N bus bar have a PN parallel section in which the P current path section and the N current path section run parallel to each other, and an equipotential parallel section provided in one of the P current path section and the N current path section, which is folded back at the junction between the capacitor bus bar and the connecting bus bar.

[0008] The disclosed power conversion device includes a busbar unit having a connecting busbar, which is more easily deformed by external forces than the capacitor busbar. Therefore, when electrically connecting a semiconductor module and a capacitor, manufacturing variations and assembly variations can cause the connecting busbar to deform. This prevents stress from concentrating at the base of the protruding portion of the capacitor busbar, which can prevent peeling or cracking in the encapsulating resin body. This, in turn, can prevent deterioration of the capacitor's quality.

[0009] The inclusion of busbar units increases the number of joints. However, the capacitor busbars are arranged so that the angle between the joint surface of the capacitor P busbar with the connecting P busbar and the joint surface of the capacitor N busbar with the connecting N busbar is 90 degrees or greater. This allows for a PN parallel section where the P current path section and the N current path section run parallel to each other, and an equipotential parallel section that is provided in one of the P current path section and the N current path section and turns back at the joint between the capacitor busbar and the connecting busbar. Opposite currents flow through the P current path section and the N current path section that make up the PN parallel section, thereby canceling out magnetic fields and reducing inductance. Similarly, opposite currents flow through the capacitor busbar and the connecting busbar that make up the equipotential parallel section, thereby canceling out magnetic fields and reducing inductance.

[0010] As a result, it is possible to provide a power conversion device that can reduce inductance while suppressing deterioration in the quality of the capacitor.

[0011] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings.

[0012] Fig. 3 is a diagram showing a power conversion circuit and a drive system to which the power conversion device according to the first embodiment is applied. 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. 6 is a cross-sectional view showing a capacitor. Fig. 7 is a cross-sectional view showing a connection structure between a semiconductor module and a capacitor. Fig. 8 is a cross-sectional view showing a reference example. Fig. 9 is a cross-sectional view showing a reference example. Fig. 10 is a cross-sectional view showing a manufacturing method. Fig. 11 is a cross-sectional view showing a manufacturing method. Fig. 12 is a cross-sectional view showing a power conversion device according to a second embodiment.

[0013] 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.

[0014] First Embodiment A power conversion device according to this embodiment is applied to, for example, a mobile body using a rotating electric machine as a drive source. Examples of the mobile body include electric vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), electric flying objects such as drones and electric vertical take-off and landing (eVTOL) aircraft, ships, construction machinery, and agricultural machinery. An example of application to a vehicle will be described below.

[0015] <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 circuit 4 .

[0016] The DC power supply 2 is a DC voltage source formed by a rechargeable secondary battery. The secondary battery is, for example, a lithium-ion battery or a nickel-metal hydride 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, that is, an electric motor. The motor generator 3 functions as a generator during regeneration. The power conversion circuit 4 converts power between the DC power supply 2 and the motor generator 3.

[0017] 1 shows an example of a power conversion circuit 4. The power conversion circuit 4 shown in FIG.

[0018] 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 7, which is a power supply line on the high potential side, and an N line 8, which is a power supply line on the low potential side. The P line 7 is connected to the positive electrode of the DC power supply 2, and the N line 8 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 7 between the DC power supply 2 and the inverter 5. The negative electrode of the smoothing capacitor 6 is connected to the N line 8 between the DC power supply 2 and the inverter 5. The smoothing capacitor 6 is connected in parallel to the DC power supply 2.

[0019] The inverter 5 is a DC-AC conversion circuit. In accordance with switching control by the control circuit, 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 7. In this way, the inverter 5 performs bidirectional power conversion between the DC power source 2 and the motor generator 3.

[0020] The inverter 5 is configured with upper and lower arm circuits 9 for three phases. The upper and lower arm circuits 9 are sometimes referred to as legs. Each upper and lower arm circuit 9 has an upper arm 9H and a lower arm 9L. The upper arm 9H and the lower arm 9L are connected in series between the P line 7 and the N line 8, with the upper arm 9H on the P line 7 side.

[0021] The connection point between the upper arm 9H and the lower arm 9L, i.e., the midpoint of the upper and lower arm circuits 9, is connected to the corresponding phase winding 3a of the motor generator 3 via an output line 10. Of the upper and lower arm circuits 9, the U-phase upper and lower arm circuit 9U is connected to the U-phase winding 3a via the output line 10. The V-phase upper and lower arm circuit 9V is connected to the V-phase winding 3a via the output line 10. The W-phase upper and lower arm circuit 9W is connected to the W-phase winding 3a via the output line 10.

[0022] Each of the upper and lower arm circuits 9 (9U, 9V, 9W) has a series circuit 11. The upper and lower arm circuits 9 may have one or more series circuits 11. When there are multiple series circuits 11, the series circuits 11 are connected in parallel to each other to form one phase of the upper and lower arm circuit 9. Each of the illustrated upper and lower arm circuits 9 has one (single) series circuit 11. The series circuit 11 is formed by connecting a switching element on the upper arm 9H side and a switching element on the lower arm 9L side in series between the P line 7 and the N line 8.

[0023] The number of high-side switching elements and low-side switching elements constituting the series circuit 11 is not particularly limited. It may be one or more. The illustrated series circuit 11 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 11. In other words, each of the six arms 9H, 9L of the three-phase upper and lower arm circuits 9 is composed of two switching elements connected in parallel to each other.

[0024] The illustrated switching element is an n-channel MOSFET 12. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. The two high-side MOSFETs 12 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 12 connected in parallel are turned on and off at the same timing by a common gate drive signal (drive voltage).

[0025] A freewheeling diode 13 (hereinafter referred to as FWD 13) is connected in anti-parallel to each of the MOSFETs 12. The FWD 13 may be a parasitic diode (body diode) or an external diode. In the upper arm 9H, the drain of the MOSFET 12 is connected to the P line 7. In the lower arm 9L, the source of the MOSFET 12 is connected to the N line 8. The source of the MOSFET 12 in the upper arm 9H and the drain of the MOSFET 12 in the lower arm 9L are connected to each other. The anode of the FWD 13 is connected to the source of the corresponding MOSFET 12, and the cathode is connected to the drain.

[0026] The switching element is not limited to the MOSFET 12. For example, an IGBT may be used. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. In the case of an IGBT, the FWD 13 is also connected in anti-parallel.

[0027] 1 drives switching elements constituting a power conversion circuit such as inverter 5. Drive circuit 14 supplies a drive voltage to the gate of corresponding MOSFET 12 based on a drive command from a control circuit. By applying the drive voltage, the drive circuit drives the corresponding MOSFET 12, i.e., turns it on and off. The drive circuit is sometimes referred to as a driver.

[0028] A control circuit (not shown) generates a drive command for operating the MOSFET 12 and outputs it to the drive circuit 14. 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.

[0029] The various sensors include, for example, a current sensor, a rotation angle sensor, and a voltage sensor. The current sensor detects the phase current flowing through the winding 3a of each phase. The rotation angle sensor detects the rotation angle of the rotor of the motor generator 3. The voltage sensor detects the voltage across the smoothing capacitor 6. The control circuit is configured with, for example, a processor and a memory. The control circuit outputs, for example, a PWM signal as a drive command. PWM is an abbreviation for Pulse Width Modulation.

[0030] The power conversion circuit 4 may include a converter. The converter is a DC-DC conversion circuit that converts a DC voltage into a DC voltage of a different value, for example. The converter is provided between the DC power supply 2 and the smoothing capacitor 6. The converter is configured to include, for example, a reactor and the above-mentioned upper and lower arm circuits 9. This configuration allows for voltage step-up and step-down. The power conversion circuit 4 may also include a filter capacitor that removes power supply noise from the DC power supply 2. The filter capacitor is provided between the DC power supply 2 and the converter.

[0031] <Power Converter> Fig. 2 is a plan view showing the power converter of this embodiment. In Fig. 2, some elements of the power converter, such as the circuit board and signal terminals, are omitted so that the arrangement of the semiconductor modules and busbar units can be seen. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a cross-sectional view showing a capacitor.

[0032] The power conversion device 20 provides the above-described power conversion circuit 4. The power conversion device 20 includes a housing 30, semiconductor modules 40, capacitors 50, a busbar unit 60, and a circuit board 70. The illustrated power conversion device 20 includes multiple semiconductor modules 40. Hereinafter, the direction perpendicular to the main surface of the semiconductor module 40 is referred to as the Z direction. The direction perpendicular to the Z direction and in which the multiple semiconductor modules 40 are arranged is referred to as the Y direction. The direction perpendicular to both the Y direction and the Z direction is referred to as the X direction. The X direction, Y direction, and Z direction are mutually orthogonal. Unless otherwise specified, a shape viewed from the Z direction, in other words, a shape along the XY plane defined by the X direction and the Y direction, is referred to as a planar shape. The planar view from the Z direction may sometimes be simply referred to as a planar view. When describing the relative positions of two components, the position of the component closer to the base 31 in the Z direction may sometimes be referred to as the lower position, and the position of the component farther from the base 31 may sometimes be referred to as the upper position. First, the schematic configuration of each element will be described. First, each element will be described.

[0033] <Housing> As shown in Figures 2 and 3, the housing 30 houses the other elements that make up the power conversion device 20. The housing 30 may be a metal housing made of a metal material such as aluminum, or a resin housing made of a resin material. It may also be a housing containing a metal material and a resin material. To dissipate heat generated by the semiconductor module 40, the capacitor 50, etc., it is preferable to use a housing containing a metal material, more preferably a metal housing. The housing 30 may be made of a single member or a combination of multiple members.

[0034] The illustrated housing 30 has a base 31 and a sidewall 32. The housing 30 is formed using a metal material including aluminum. The base 31 supports a semiconductor module 40 and a capacitor 50. The semiconductor module 40 and the capacitor 50 are arranged on one surface of the base 31. The illustrated base 31 forms the bottom wall of the housing 30. The sidewall 32 is continuous with the base 31. The sidewall 32, together with the base 31, defines a storage section.

[0035] The base 31 provides a heat dissipation function for dissipating heat generated by the semiconductor module 40 and the capacitor 50. To enhance the heat dissipation function, fins may be provided on the back side of the base 31. Also, a flow path through which a coolant flows may be provided in the base 31. The housing 30 may have a cover that covers the storage space defined by the base 31 and the side wall 32. The housing 30 may have storage space not only on one side of the base 31 but also on the back side. The housing 30 may be configured without the side wall 32.

[0036] <Semiconductor Module> The semiconductor module 40 constitutes the upper and lower arm circuits 9, i.e., the inverter 5, described above. The semiconductor module 40 may also be referred to as a power module, a semiconductor device, or the like. The power conversion device 20 includes three semiconductor modules 40. One semiconductor module 40 provides one series circuit 11, i.e., one phase of the upper and lower arm circuits 9. The multiple semiconductor modules 40 include a semiconductor module 40U that constitutes the upper and lower arm circuit 9U, a semiconductor module 40V that constitutes the upper and lower arm circuit 9V, and a semiconductor module 40W that constitutes the upper and lower arm circuit 9W.

[0037] All the semiconductor modules 40 have a common structure. Each semiconductor module 40 includes a main body 41 and external connection terminals protruding from the main body 41. The main body 41 includes a semiconductor element 411, a sealing body 412, and the like.

[0038] The semiconductor element 411 is formed by forming a switching element on a semiconductor substrate made of silicon (Si) or a wide bandgap semiconductor with a wider bandgap than silicon. The switching element has a vertical structure so that the main current flows in the thickness direction of the semiconductor substrate. Examples of wide bandgap semiconductors include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond. The semiconductor element 411 is sometimes called a power element, a semiconductor chip, or the like.

[0039] The illustrated semiconductor element 411 is formed by forming the above-described n-channel MOSFET 12 and FWD 13 on a semiconductor substrate made of SiC. The MOSFET 12 has a vertical structure so that a main current flows in the thickness direction of the semiconductor element 411 (semiconductor substrate). The semiconductor element 411 has main electrodes (not shown) on both sides of the semiconductor element 411 in the thickness direction. The semiconductor element 411 has, as main electrodes, a source electrode on the front surface and a drain electrode on the back surface. The source electrode is formed on a portion of the front surface. The drain electrode is formed on almost the entire back surface.

[0040] A main current flows between the drain electrode and the source electrode. The semiconductor element 411 has a pad (not shown) that is a signal electrode on the surface where the source electrode is formed. The semiconductor element 411 is arranged so that its plate thickness direction is approximately parallel to the Z direction. The illustrated semiconductor element 411 includes two semiconductor elements 411H that provide switching elements on the high side of the series circuit 11 and two semiconductor elements 411L that provide switching elements on the low side of the series circuit 11. The semiconductor elements 411H and 411L are aligned in the X direction. The two semiconductor elements 411H are aligned in the Y direction. Similarly, the two semiconductor elements 411L are aligned in the Y direction.

[0041] The four semiconductor elements 411 provide four switching elements for one series circuit 11. The semiconductor module 40 includes the same number of semiconductor elements 411 as the number of switching elements that make up one series circuit 11. When the series circuit 11 includes two switching elements, the semiconductor module 40 includes one each of the semiconductor elements 411H and 411L.

[0042] The sealing body 412 seals some of the other elements that make up the semiconductor module 40. The remaining parts of the other elements are exposed outside the sealing body 412. The sealing body 412 seals the semiconductor element 411, a portion of each of the external connection terminals, etc. The other portions of each of the external connection terminals protrude outside the sealing body 412. The sealing body 412 is made of, for example, resin. The sealing body 412 is molded by transfer molding using, for example, epoxy resin. The sealing body 412 has a generally rectangular shape in plan view with the longitudinal direction in the X direction. The sealing body 412 forms the outer periphery of the main body 41.

[0043] The sealing body 412, i.e., the main body 41, has main surfaces 413 and 414 and side surfaces as surfaces forming the outer shell. The main surface 414 is the surface opposite to the main surface 413 in the Z direction. The main surfaces 413 and 414 are, for example, flat surfaces. The main surfaces 413 and 414 are surfaces that are approximately perpendicular to the Z direction. The side surfaces are surfaces that connect the main surfaces 413 and 414.

[0044] The external connection terminals include a power supply terminal 42, an output terminal 43, and a signal terminal 44. The power supply terminal 42 and the output terminal 43 are external connection terminals electrically connected to the main electrodes of the semiconductor element 411 and may be referred to as main terminals, etc. The power supply terminals 42 include a P terminal 42P and an N terminal 42N. The P terminal 42P is electrically connected to the drain electrode of the semiconductor element 411H. The N terminal 42N is electrically connected to the source electrode of the semiconductor element 411L. The P terminal 42P may be referred to as a high-potential power supply terminal, a positive terminal, etc. The N terminal 42N may be referred to as a low-potential power supply terminal, a negative terminal, etc. The P terminal 42P and the N terminal 42N protrude to the outside from a common side surface of the main body 41. The P terminal 42P and the N terminal 42N protrude to the outside from a side surface facing the capacitor 50 in the X direction. The protruding portions of the P terminal 42P and the N terminal 42N are aligned in the Y direction.

[0045] The output terminal 43 is electrically connected to the connection point between the source electrode of the semiconductor element 411H and the drain electrode of the semiconductor element 411L, i.e., the connection point (midpoint) of the series circuit 11. The output terminal 43 protrudes to the outside from the side surface of the main body 41 opposite to the side surface from which the P terminal 42P and the N terminal 42N protrude. The output terminal 43 protrudes to the outside from the side surface opposite to the surface facing the capacitor 50. The output terminal 43 may also be referred to as an O terminal, an AC terminal, etc. The output terminal 43 is connected to the corresponding winding 3a of the motor-generator 3, for example, via an output terminal block (not shown).

[0046] The signal terminals 44 are external connection terminals electrically connected to pads of the semiconductor element 411. The signal terminals 44 protrude to the outside from the main body 41 (sealing body 412). For example, the signal terminals 44 connected to pads of the semiconductor element 411H protrude from the side surface of the sealing body 412 that is shared with the power supply terminals 42. The signal terminals 44 connected to pads of the semiconductor element 411L protrude from the side surface of the sealing body 412 that is shared with the output terminals 43. The protruding portions of the signal terminals 44 have bent portions that extend upward.

[0047] In addition to the above-mentioned elements, the semiconductor module 40 also includes wiring members (not shown). The wiring members provide a wiring function for electrically connecting the main electrodes and main terminals of the semiconductor element 411. The wiring members provide a heat dissipation function for dissipating heat from the semiconductor element 411. The wiring members are arranged, for example, to sandwich the semiconductor element 411 in the Z direction. The wiring members may be, for example, a substrate having metal bodies arranged on both sides of an insulating base material, or may be a heat sink that is a metal member. The heat sink may be provided as part of the lead frame. The wiring members may be entirely sealed by the sealing body 412, or may be partially exposed from at least one of the main surfaces 413, 414 of the main body 41. Exposing the wiring members can improve heat dissipation.

[0048] The semiconductor module 40 described above is disposed on the base 31 with the main surface 414 facing the base 31. A TIM may be interposed between the main surface 414 and the base 31. TIM is an abbreviation for Thermal Interface Material. A heat dissipation member (cooling member) (not shown) may be disposed above the semiconductor module 40. A TIM may be interposed between the main surface 414 and the heat dissipation member.

[0049] As shown in Fig. 2, the three semiconductor modules 40 are lined up in the Y direction. That is, the multiple semiconductor modules 40 are arranged side by side along the Y direction. The three semiconductor modules 40 are lined up in the order of semiconductor module 40U, semiconductor module 40V, and semiconductor module 40W. In addition, the side surfaces of adjacent semiconductor modules 40 face each other in the X direction with a predetermined gap between them. Specifically, the side surface of semiconductor module 40U faces the side surface of semiconductor module 40V. The side surface of semiconductor module 40V faces the side surface of semiconductor module 40W.

[0050] <Capacitor> The capacitor 50 serves as the smoothing capacitor 6 described above. The capacitor 50 includes a case 51, a capacitor element 52, a sealing resin body 53, a capacitor bus bar 54, and an insulator 55. The illustrated capacitor 50 has a generally rectangular shape in plan view with the Y direction as the longitudinal direction. The capacitors 50 are arranged side by side in the X direction relative to the semiconductor module 40.

[0051] The case 51 may be formed using a metal material such as aluminum, or may be formed using a resin material. The case 51 has a cylindrical shape with a bottom. The illustrated case 51 is made of metal. The capacitor element 52 is housed in the case 51. The illustrated capacitor element 52 is a film capacitor element. The capacitor element 52 is formed, for example, by winding a film around the Z direction as an axis. The capacitor element 52 has electrodes 521, 522 on both end surfaces in the Z direction. As an example, the negative electrode 521 is provided on the bottom surface, and the positive electrode 522 is provided on the top surface.

[0052] The sealing resin body 53 is made of an electrically insulating resin material such as epoxy resin. The sealing resin body 53 fills the case 51 and seals the capacitor element 52. The sealing resin body 53 seals a part of the capacitor bus bar 54, including the connection portion with the capacitor element 52.

[0053] The capacitor bus bar 54 is a metal plate made of a metal with good conductivity, such as Cu. The capacitor bus bar 54 is connected to the corresponding electrodes 532, 522 by, for example, soldering, resistance welding, or laser welding. The capacitor bus bar 54 protrudes from one surface 531 of the sealing resin body 53 to the outside of the sealing resin body 53. The capacitor bus bar 54 has an embedded portion 541 sealed by the sealing resin body 53 and a protruding portion 542 protruding from the one surface 531.

[0054] The capacitor bus bars 54 include an N bus bar 54N connected to the negative electrode 521 and a P bus bar 54P connected to the positive electrode 522. The N bus bar 54N corresponds to the capacitor N bus bar, and the P bus bar 54P corresponds to the capacitor P bus bar. The N bus bar 54N and the P bus bar 54P are arranged so that the angle θ between the joint surfaces 543 with the corresponding coupling bus bars 61 is 90 degrees or greater. In the illustrated capacitor bus bar 54, the joint surfaces 543 are approximately parallel to the main surfaces 413, 414.

[0055] The protrusion 542 of the N bus bar 54N has a first extending portion 54N1 and a second extending portion 54N2. The first extending portion 54N1 extends upward in the Z direction from one surface 531. The second extending portion 54N2 is continuous with the upper end of the first extending portion 54N1 and extends in the X direction toward the semiconductor module 40. The bend between the first extending portion 54N1 and the second extending portion 54N2 forms an angle of approximately 90 degrees.

[0056] The protrusion 542 of the P bus bar 54P has a first extending portion 54P1 and a second extending portion 54P2. The first extending portion 54P1 extends upward in the Z direction from one surface 531. The second extending portion 54P2 is continuous with the upper end of the first extending portion 54P1 and extends in the X direction away from the semiconductor module 40. In other words, the second extending portions 54P2 and 54N2 extend in opposite directions. The entire length of the second extending portion 54P2 is located above the sealing resin body 53. The bend between the first extending portion 54P1 and the second extending portion 54P2 forms an angle of approximately 90 degrees.

[0057] The first extension portions 54N1, 54P1 have plate surfaces facing each other in the X direction to reduce inductance. The first extension portions 54N1, 54P1 run parallel to each other. The second extension portions 54N2, 54P2 are aligned in the X direction. The joint surface 543 of the N bus bar 54N and the joint surface 543 of the P bus bar 54P are located at approximately the same height in the Z direction. The angle θ between the joint surfaces 543 is approximately 180 degrees. Approximately 180 degrees may not only be 180 degrees but may also include errors due to manufacturing variations. The joint surfaces 543 are the upper surfaces of the second extension portions 54N2, 54P2.

[0058] The insulator 55 is interposed between the N bus bar 54N and the P bus bar 54P, insulating and separating the N bus bar 54N and the P bus bar 54P. The insulator 55 is, for example, a resin molded body. The insulator 55 corresponds to a first insulator. Like the capacitor bus bar 54, a portion of the insulator 55 is sealed in the sealing resin body 53, and another portion protrudes outward from the one surface 531. The insulator 55 has a first extension portion 551 and a second extension portion 552. The first extension portion 551 extends upward in the Z direction from the one surface 531. The first extension portion 551 is interposed between the first extension portions 54N1 and 54P1. The second extension portion 552 is continuous with the upper end of the first extension portion 551 and extends in the X direction toward the semiconductor module 40. The second extension portion 552 is disposed on the second extension portion 54N2. The second extension portion 552 covers part of the second extension portion 54N2.

[0059] The capacitor bus bar 54 electrically connects the capacitor 50 (capacitor element 52) ​​and the semiconductor module (semiconductor element 411). The capacitor bus bar 54 is a terminal portion that connects the capacitor 50 to the semiconductor module 40. DC terminal portions 56 are connected to the capacitor bus bar 54. The DC terminal portions 56 are terminal portions for electrically connecting the capacitor 50 to a DC power supply (DC power supply 2). The DC terminal portions 56 include an N-terminal portion 56N that is electrically connected to the negative electrode of the DC power supply and a P-terminal portion 56P that is electrically connected to the positive electrode of the DC power supply. The N-terminal portion 56N is connected to the protruding portion 542 of the N-bus bar 54N. The P-terminal portion 56P is connected to the protruding portion 542 of the P-bus bar 54P. In the illustrated capacitor 50, the N-terminal portion 56N and the P-terminal portion 56P are connected to second extension portions 54N2, 54P2 of the protruding portion 542 and extend in the Y direction. The DC terminal portion 56 is electrically connected to a DC power supply via an input terminal block (not shown).

[0060] <Busbar Unit> The busbar unit 60 is a wiring member that electrically connects the semiconductor module 40 and the capacitor 50. The busbar unit 60 may also be referred to as a busbar assembly, a busbar subassembly, or the like. The busbar unit 60 includes a coupling busbar 61 and an insulator 62. The coupling busbar 61 and the insulator 62 are integrated by press-fitting or the like.

[0061] The connecting bus bars 61 are metal plates made of a metal with good conductivity, such as Cu. The connecting bus bars 61 include an N bus bar 61N and a P bus bar 61P. The N bus bar 61N corresponds to the connecting N bus bar, and the P bus bar 61P corresponds to the connecting P bus bar.

[0062] The N bus bar 61N electrically connects the N terminal 42N of the semiconductor module 40 and the N bus bar 54N of the capacitor 50. The P bus bar 61P electrically connects the P terminal 42P of the semiconductor module 40 and the P bus bar 54P of the capacitor 50. The N bus bar 61N and the P bus bar 61P are arranged so that their plate surfaces face each other over a portion of their entire lengths in order to reduce inductance.

[0063] The illustrated N bus bar 61N has approximately three extension portions. The first extension portion 61N1 extends in the X direction and is joined to the N terminal 42N. The second extension portion 61N2 is connected to the end of the first extension portion 61N1 facing the capacitor 50 and extends upward in the Z direction. The third extension portion 61N3 is connected to the upper end of the second extension portion 61N2 and extends toward the capacitor 50 in the X direction. The third extension portion 61N3 extends to a position where it overlaps with the second extension portion 54N2 of the N bus bar 54N and is joined to the second extension portion 54N2. The bend between the first extension portion 61N1 and the second extension portion 61N2 and the bend between the second extension portion 61N2 and the third extension portion 61N3 both form an angle of approximately 90 degrees.

[0064] The illustrated P bus bar 61P has approximately four extension portions. The first extension portion 61P1 extends in the X direction and is joined to the P terminal 42P. The second extension portion 61P2 is connected to the end of the first extension portion 61P1 on the capacitor 50 side and extends upward in the Z direction. The third extension portion 61P3 is connected to the upper end of the second extension portion 61P2 and extends toward the capacitor 50 in the X direction. The fourth extension portion 61P4 is approximately L-shaped in a plan view in the Y direction. The fourth extension portion 61P4 is connected to the end of the third extension portion 61P3 on the capacitor 50 side and extends toward the capacitor 50 in the X direction. The fourth extension portion 61P4 extends to a position overlapping the second extension portion 54P2 of the P bus bar 54P and is joined to the second extension portion 54P2. The bent portion between the first extending portion 61P1 and the second extending portion 61P2 and the bent portion between the second extending portion 61P2 and the third extending portion 61P3 both form an angle of approximately 90 degrees.

[0065] The first extension portions 61N1, 61P1 are provided for each semiconductor module 40. The first extension portions 61N1 and the first extension portions 61P1 are arranged alternately in the Y direction. The side surfaces of the first extension portions 61N1 and the first extension portions 61P1 face each other in the Y direction. The plate surfaces of the second extension portions 61N2, 61P2 face each other in the X direction. The plate surfaces of the third extension portions 61N3, 61P3 face each other in the Z direction. Both the N bus bar 61N and the P bus bar 61P include a crank-shaped portion.

[0066] The insulator 62 is interposed between the N bus bar 61N and the P bus bar 61P, and insulates and separates the N bus bar 61N and the P bus bar 61P. The insulator 62 is, for example, a resin molded body. The insulator 62 corresponds to the second insulator. The insulator 62 has a first extension portion 621 and a second extension portion 622. The first extension portion 621 extends in the Z direction and is interposed between the second extension portions 61N2 and 61P2. The second extension portion 622 is continuous with the upper end of the first extension portion 621 and extends in the X direction toward the capacitor 50. The second extension portion 622 is interposed between the third extension portions 61N3 and 61P3. The second extension portion 622 extends to a position where it overlaps with the second extension portion 552 of the insulator 55 in a plan view. The second extending portion 622 extends to a position closer to the P bus bar 54P than the third extending portion 61N3. The stacked portion of the insulators 55, 62 is interposed between the third extending portion 61P3 of the P bus bar 61P and the second extending portion 54N2 of the N bus bar 54N.

[0067] The coupling bus bar 61 is connected to the corresponding power supply terminals 42 and capacitor bus bars 54 by, for example, laser welding, soldering, or resistance welding. The illustrated coupling bus bar 61 is connected to the corresponding power supply terminals 42 and capacitor bus bars 54 by laser welding. To enable laser welding, a through hole 63 is provided in the third extension portion 61P3 of the P bus bar 61P. The through hole 63 is an opening provided for laser welding the third extension portion 61N3 of the N bus bar 61N located below the third extension portion 61P3 to the second extension portion 54N2 of the N bus bar 54N. The insulators 55 and 62 are arranged to avoid the through hole 63. The number of through holes 63 may be one or more. The illustrated P bus bar 61P has two through holes 63. The two through holes 63 are aligned in the Y direction.

[0068] The busbar unit 60 further includes detection terminals 64 and 65. The detection terminals 64 and 65 are connected to the corresponding connecting bus bars 61. The detection terminals 64 and 65 are, for example, connected continuously and integrally to the connecting bus bars 61. The detection terminal 64 is connected to the third extension portion 61P3 of the P bus bar 61P and detects the potential of the P terminal 42P, i.e., the drain potential of the semiconductor element 411H. The detection terminal 65 is connected to the third extension portion 61N3 of the N bus bar 61N and detects the potential of the N terminal 42N, i.e., the source potential of the semiconductor element 411L. The illustrated busbar unit 60 includes three detection terminals 64 and one detection terminal 65. The detection terminals 64 and 65 extend upward in the Z direction from the third extension portions 61N3 and 61P3 of the corresponding connecting bus bars 61. The detection terminals 64 and 65 are sometimes referred to as desat terminals.

[0069] <Circuit Board> Although not shown, the circuit board 70 includes a wiring board formed by arranging conductors including a wiring layer on an insulating base material such as resin, electronic components mounted on the wiring board, connectors, etc. The mounted electronic components and conductors form a circuit. The circuit board 70 includes the drive circuit 14 described above.

[0070] The circuit board 70 is disposed so as to overlap with parts of the semiconductor modules 40, the bus bar unit 60, and the capacitor 50 in a plan view in the Z direction. The circuit board 70 is disposed above the three semiconductor modules 40. The signal terminals 44 of the three semiconductor modules 40 are mounted on the circuit board 70. The detection terminals 64, 65 are mounted on the circuit board 70. The circuit board 70 is housed in the housing 30.

[0071] <Connection Structure Between Semiconductor Module and Capacitor> Fig. 5 is a cross-sectional view showing the connection structure between a semiconductor module and a capacitor. Fig. 5 is a diagram showing the periphery of a busbar unit in a power conversion device. For convenience, Fig. 5 omits the portion of the capacitor that is sealed in the sealing resin body.

[0072] As described above, the N terminal 42N of the semiconductor module 40 and the N bus bar 54N of the capacitor 50 are electrically connected via the N bus bar 61N of the bus bar unit 60. The P terminal 42P of the semiconductor module 40 and the P bus bar 54P of the capacitor 50 are electrically connected via the P bus bar 61P of the bus bar unit 60. The joined capacitor bus bar 54 and coupling bus bar 61 provide a current path portion. The power conversion device 20 includes an N current path portion 80N and a P current path portion 80P.

[0073] The N current path portion 80N includes an N bus bar 54N and an N bus bar 61N. The P current path portion 80P includes a P bus bar 54P and a P bus bar 61P. In FIG. 5 , the current flowing through the N current path portion 80N is indicated by a dashed line, and the current flowing through the P current path portion 80P is indicated by a two-dot chain line. The N current path portion 80N and the P current path portion 80P have a PN parallel portion 81 and an equal-potential parallel portion 82. The PN parallel portion 81 is a portion where the N current path portion 80N and the P current path portion 80P run parallel to each other. In the PN parallel portion 81, currents flow in opposite directions in the N current path portion 80N and the P current path portion 80P, thereby canceling out magnetic fields and reducing inductance. The same-potential parallel portion 82 is provided in one of the N current path portion 80N and the P current path portion 80P, and is a parallel portion of the same potential that is folded back at the joint between the capacitor bus bar 54 and the connecting bus bar 61. The folded back structure reverses the direction of the current, thereby canceling out the magnetic field and reducing inductance.

[0074] In the illustrated power conversion device 20, the N current path portion 80N constituting the PN parallel running portion 81 includes a first extension portion 54N1 and a second extension portion 54N2 of the N bus bar 54N, and a second extension portion 61N2 and a third extension portion 61N3 of the N bus bar 61N. The P current path portion 80P constituting the PN parallel running portion 81 includes a first extension portion 54P1 of the P bus bar 54P, and a second extension portion 61P2 and a third extension portion 61P3 of the P bus bar 61P. The P current path portion 80P also has an equal potential parallel running portion 82. The equal potential parallel running portion 82 includes the second extension portion 54P2 of the P bus bar 54P and the fourth extension portion 61P4 of the P bus bar 61P. The equal potential parallel running portion 82 is folded back at a joint 83 between the P bus bars 54P and 61P.

[0075] Furthermore, the thickness t1 of the capacitor bus bar 54 is greater than the thickness t1 of the connecting bus bar 61. In other words, the connecting bus bar 61 is thinner than the capacitor bus bar 54. This results in a structure in which the connecting bus bar 61 is more likely to deform than the capacitor bus bar 54 when an external force is applied. As described above, the connecting bus bar 61 includes a crank shape, and the joint 83 and the joint 84 between the power supply terminal 42 and the connecting bus bar 61 are located at different positions in the direction perpendicular to the main surfaces 413, 414. The joint 83 corresponds to a first joint, and the joint 84 corresponds to a second joint.

[0076] The detection terminal 64 (65) is disposed between the joints 83 and 84 in the X direction. The detection terminal 64 (65) is disposed closer to the joints 83 and 84 than the joint 85 between the power supply terminal 42 and the connecting bus bar 61. As described above, the joint surface 543 is substantially parallel to the main surfaces 413 and 414. The joint surface 611 of the connecting bus bar 61 with the power supply terminal 42 is also substantially parallel to the main surfaces 413 and 414.

[0077] Summary of the First Embodiment Figures 6, 7, and 8 are cross-sectional views showing a reference example. In the reference example, the reference symbols of elements related to this embodiment are given the suffix "r." For convenience, the portion of the capacitor sealed in the sealing resin body is omitted in Figures 6 to 8. Insulators are omitted in Figures 6 and 7.

[0078] 6 and 7 do not include a bus bar unit. Therefore, the capacitor bus bar 54r is joined to the corresponding power terminal 42r. Due to manufacturing variations and assembly variations, gaps may occur between the capacitor bus bar 54r and the power terminal 42r, as shown in FIG.

[0079] When joining by welding or other methods, it is necessary to change the load using a chuck to eliminate the gap, which, for example, deforms the capacitor bus bar 54r. If the capacitor bus bar 54r deforms, stress concentrates at the base of the protrusion 542r, which may cause peeling or cracking in the sealing resin body 53r. Peeling or cracking may allow moisture to enter the interior, resulting in a change in capacitance. Peeling or cracking may also cause poor insulation. In other words, there is a risk of deterioration in the quality of the capacitor 50r.

[0080] The reference example shown in FIG. 8 includes a busbar unit 60r. In FIG. 8, the second extension portion 54P2r of the P busbar 54Pr extends in the same direction as the second extension portion 54N2r of the N busbar 54Nr. The insulator 55r is interposed between the second extension portions 54N2r, 54P2r. In this configuration, the joint portion 83r is located closer to the semiconductor module 40r than the first extension portion 551r of the insulator 55r. This causes the joint portion 84r to be located farther away from the capacitor 50r. This increases the size in the X direction. As shown in FIG. 8, the length in the X direction from the center of the first extension portion 551r to the main body portion 41r of the semiconductor module 40r is L1r. Furthermore, the path length is increased, resulting in increased inductance.

[0081] The power conversion device 20 of this embodiment includes a busbar unit 60. The connecting busbar 61 is structured to be more easily deformed by external forces than the capacitor busbar 54. When electrically connecting the semiconductor module 40 and the capacitor 50, the power terminal 42 and the connecting busbar 61 are joined as shown in FIG. 9. Manufacturing and assembly variations can cause gaps between the connecting busbar 61 and the capacitor busbar 54 in the joined state. When the connecting busbar 61 and the capacitor busbar 54 are joined while adjusting the load with a chuck to eliminate the gap, the connecting busbar 61 is primarily deformed as shown in FIG. 10. This causes stress to concentrate at the base of the protruding portion 542 of the capacitor busbar 54, preventing peeling and cracking of the encapsulating resin body 53. In other words, quality degradation of the capacitor 50 is suppressed. FIGS. 9 and 10 are cross-sectional views illustrating a manufacturing method. For convenience, the portions of the capacitor 50 sealed in the encapsulating resin body 53 are omitted from FIGS. 9 and 10. The insulators 55 and 62 are also omitted.

[0082] The inclusion of the busbar unit 60 increases the number of joints. However, the capacitor busbar 54 is arranged so that the angle formed by the joint surface 543 of the P busbar 54P with the P busbar 61P and the joint surface 543 of the N busbar 54N with the N busbar 61N is 90 degrees or greater. This allows for a PN parallel running portion 81 in which the P current path portion 80P and the N current path portion 80N run parallel to each other, and an equal-potential parallel running portion 82 in which the joint portion between the capacitor busbar 54 and the connecting busbar 61 is folded back. Opposite currents flow through the P current path portion 80P and the N current path portion 80N that make up the PN parallel running portion 81, thereby canceling out magnetic fields and reducing inductance. Similarly, opposite currents flow through the capacitor busbar 54 and the connecting busbar 61 that make up the equal-potential parallel running portion 82 due to their folded back structure, thereby canceling out magnetic fields and reducing inductance.

[0083] As described above, the power conversion device 20 of this embodiment can reduce inductance while suppressing quality degradation of the capacitor 50. Furthermore, the size in the X direction can be reduced. As shown in FIG. 5 , the length in the X direction from the center of the first extension portion 551 of the insulator 55 to the main body portion 41 of the semiconductor module 40 is L1. FIG. 8 also shows the length L1. The length L1 is shorter than the length L1r of the reference example. Therefore, the size in the X direction can be reduced. Because the length L1 is short, the lengths of the P current path portion 80P and the N current path portion 80N are also shortened, thereby reducing inductance.

[0084] As illustrated, the insulator 55 of the capacitor 50 and the insulator 62 of the busbar unit 60 may be arranged to overlap at least a portion of the PN parallel portion 81. If there is a risk of portions where neither the insulator 55 nor the insulator 62 is located, a distance sufficient to ensure insulation between the P current path portion 80P and the N current path portion 80N is required. By arranging them in an overlapping manner, at least one of the insulators 55 and 62 is interposed between the P current path portion 80P and the N current path portion 80N, even if manufacturing or assembly variations occur in the X direction. This allows the P current path portion 80P and the N current path portion 80N to be closer together. This enhances the effect of magnetic field cancellation and further reduces inductance. Furthermore, the overall size in the Z direction, for example, can be reduced.

[0085] As shown in the example, the joint surface 543 of the capacitor bus bar 54 with the coupling bus bar 61 may be parallel to the main surfaces 413, 414 of the semiconductor module 40. In other words, the angle formed by the joint surface 543 of the P bus bar 54P and the joint surface 543 of the N bus bar 54N may be 180 degrees. This not only achieves the above-mentioned effects, but also makes it possible to reduce the size of the power conversion device 20 in the Z direction, i.e., to reduce its height.

[0086] As illustrated, the joint surface 611 of the connecting bus bar 61 with the power terminal 42 may be parallel to the main surfaces 413, 414 of the semiconductor module 40. In other words, a lap joint structure may be used. In a lap joint structure in which the plate surfaces face each other in the X direction, chucking is performed from both sides in the X direction, which increases the size in the X direction by the space required for chucking, and also increases in inductance. According to the illustrated lap joint structure, chucking is performed in the Z direction, so the space between the second extension portions 61N2, 61P2 and the main body portion 41 can be narrowed compared to a bow joint structure. This further reduces inductance. Furthermore, the size in the X direction can be further reduced.

[0087] As shown in the example, the thickness of the connecting bus bar 61 may be thinner than the thickness of the capacitor bus bar 54. This makes the connecting bus bar 61 more susceptible to deformation due to external forces. Therefore, even if gaps occur due to manufacturing variations when joining the connecting bus bar 61 and the capacitor bus bar 54, the connecting bus bar 61 deforms, thereby preventing peeling and cracking of the sealing resin body 53.

[0088] As illustrated, the joint 83 between the capacitor bus bar 54 and the connecting bus bar 61 and the joint 84 between the power supply terminal 42 and the connecting bus bar 61 may be positioned differently in the direction perpendicular to the main surfaces 413, 414. That is, the positions of the joints 83, 84 may be different in the Z direction. This increases the length in the Z direction, making the connecting bus bar 61 more easily deformable. Furthermore, the connecting bus bar 61 can be made more easily deformable while suppressing an increase in its size in the X direction. For example, the connecting bus bar 61 may include a crank-shaped portion. This makes it possible to make the connecting bus bar 61 more easily deformable while suppressing an increase in its size in the X direction.

[0089] As illustrated, the bus bar unit 60 may be provided with detection terminals 64, 65 that are connected to the connecting bus bar 61 and mounted on the circuit board 70. The detection terminals 64, 65 may be provided close to the capacitor 50 in the X direction, which is the alignment direction of the semiconductor module 40 and the capacitor 50. If the detection terminals 64, 65 are provided close to the semiconductor module 40, it is necessary to ensure a length for chucking that avoids the detection terminals 64, 65, which increases the size in the X direction. However, by providing the detection terminals close to the capacitor 50, it is possible to suppress an increase in size in the X direction. It is also possible to suppress an increase in inductance.

[0090] For example, the detection terminals 64, 65 may be provided in a position in the X direction between the joint 83 of the P bus bars 54P, 61P and the joint 84 of the N bus bars 54N, 61N. In this way, the detection terminals 64, 65 are less likely to get in the way of the chuck when forming the joints 83, 84, so there is no need to extend the path to avoid them, and inductance can be reduced.

[0091] As illustrated, the capacitor 50 may be provided with a DC terminal portion 56 connected to the capacitor bus bar 54. In this way, the electrical path between the DC power supply and the semiconductor module 40 is formed via the DC terminal portion 56, the capacitor bus bar 54, and the connecting bus bar 61, without passing through the capacitor element 52. This makes it possible to suppress the influence of heat generated by the DC component on the capacitor element 52.

[0092] The arrangement of the N bus bar 54N, the P bus bar 54P, the N bus bar 61N, and the P bus bar 61P is not limited to the example described above. The N bus bar 54N and the P bus bar 54P may be interchanged, and the N bus bar 61N and the P bus bar 61P may be interchanged. In other words, the N bus bars 54N and 61N may form the same potential parallel running portion 82.

[0093] The number and arrangement of the external connection terminals provided on the semiconductor module 40 are not limited to the above example. One semiconductor module 40 may have a plurality of P terminals 42P and N terminals 42N. It may also have a plurality of output terminals 43.

[0094] Second Embodiment This embodiment is a modification of the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the angle θ between the joint surface 543 of the P bus bar 54P and the joint surface 543 of the N bus bar 54N was set to approximately 180 degrees. Alternatively, the angle θ may be set to an angle other than 180 degrees.

[0095] Fig. 11 is a cross-sectional view showing a connection structure between a semiconductor module and a capacitor in a power conversion device according to a second embodiment. Fig. 11 is a view showing the periphery of a busbar unit in the power conversion device. Fig. 11 corresponds to Fig. 5. For convenience, the portion of the capacitor sealed in the sealing resin body is omitted.

[0096] Of the capacitor bus bars 54, the P bus bar 54P extends upward in the Z direction from one surface 531. The second extending portion 54P2 is continuous with the upper end of the first extending portion 54P1 and extends upward. The N bus bar 54N has the same configuration as described in the preceding embodiment. As a result, the angle between the joint surface 543 of the N bus bar 54N and the joint surface 543 of the P bus bar 54P is approximately 90 degrees.

[0097] The fourth extension portion 61P4 of the P bus bar 61P is connected to the end of the third extension portion 61P3 on the capacitor 50 side and extends upward. The joint 83 of the P bus bars 54P, 61P has a cross-joint structure in which the plate surfaces are perpendicular to the X direction. The N bus bar 61N has the same configuration as shown in the preceding embodiment. The insulators 55, 62 also have the same configuration as described in the preceding embodiment.

[0098] The N current path portion 80N and the P current path portion 80P have a PN parallel portion 81 and an equal-potential parallel portion 82. As in the preceding embodiment, the equal-potential parallel portion 82 includes the second extension portion 54P2 of the P bus bar 54P and the fourth extension portion 61P4 of the P bus bar 61P. The equal-potential parallel portion 82 has a folded structure in which the joint portion 83 is folded back. The stacking direction of the P bus bars 54P, 61P is the X direction. The PN parallel portion 81 has the same configuration as that shown in the preceding embodiment. The other configurations are the same as those described in the preceding embodiment.

[0099] Summary of the Second Embodiment As illustrated, even when the angle between the joint surface 543 of the N bus bar 54N and the joint surface 543 of the P bus bar 54P is 90 degrees, the PN parallel running portion 81 and the same potential parallel running portion 82 can be provided. This reduces inductance. Furthermore, as in the previous embodiment, the bus bar unit 60 is provided, and the connecting bus bar 61 has a structure that is more easily deformed by an external force than the capacitor bus bar 54. This reduces inductance while suppressing deterioration in the quality of the capacitor 50. Furthermore, the size in the X direction can be reduced.

[0100] The angle formed by the joint surface 543 of the P bus bar 54P with the P bus bar 61P and the joint surface 543 of the N bus bar 54N with the N bus bar 61N is not limited to 90 degrees. It may be 90 degrees or more. It may be more than 180 degrees as long as it is within a range of less than 270 degrees.

[0101] (Other Embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0102] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0103] When an element or layer is referred to as being "on," "coupled," "connected," or "coupled," it may be directly on, coupled, connected, or coupled to another element or layer, and intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly coupled" to another element or layer, no intervening elements or layers are present. Other terms used to describe relationships between elements should be construed in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used in this specification, the term "and / or" includes any and all combinations of one or more of the associated listed items. That is, a reference to A and / or B means at least one of A and B.

[0104] Spatially relative terms such as "inside," "outside," "back," "below," "low," "top," "top," and the like are used herein to facilitate the description of one element or feature's relationship to other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "directly below" other elements or features would then be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may also be oriented in other ways (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0105] (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.

[0106] <Technical Idea 1> A semiconductor module (40) having a main body (41) and power supply terminals (42) protruding from the main body; a capacitor (50) having a capacitor element (52), a sealing resin body (53) that seals the capacitor element, and a capacitor bus bar (54) that includes a portion connected to the capacitor element and a portion protruding from the sealing resin body; and a bus bar unit (60) having a coupling bus bar (61) that electrically connects the capacitor bus bar and the power supply terminals, wherein the power supply terminals include a P terminal (42P) and an N terminal (42N), the capacitor bus bar includes a capacitor P bus bar (42P) connected to the positive electrode of the capacitor element, and a capacitor N bus bar (42N) connected to the negative electrode of the capacitor element, and the coupling bus bar includes a coupling P bus bar (61P) that electrically connects the capacitor P bus bar and the P terminal, and a coupling N bus bar (61N) that electrically connects the capacitor N bus bar and the N terminal, the connecting busbars have a structure that is more easily deformed by an external force than the capacitor busbars, and the capacitor busbars are arranged so that an angle formed between a joint surface of the capacitor P busbar with the connecting P busbar and a joint surface of the capacitor N busbar with the connecting N busbar is 90 degrees or more, and a P current path section (80P) including the capacitor P busbar and the connecting P busbar, and an N current path section (80N) including the capacitor N busbar and the connecting N busbar, each have a PN parallel running section (81) in which the P current path section and the N current path section run parallel to each other, and an equipotential parallel running section (82) that is provided in one of the P current path section and the N current path section and that folds back at the joint point between the capacitor busbar and the connecting busbar.

[0107] <Technical Idea 2> The power conversion device according to Technical Idea 1, wherein the capacitor has a first insulator (55) interposed between the capacitor P bus bar and the capacitor N bus bar, the bus bar unit has a second insulator (62) interposed between the connecting P bus bar and the connecting N bus bar, and the first insulator and the second insulator overlap at least in part of the PN parallel running portion.

[0108] <Technical Concept 3> The power conversion device according to Technical Concept 1 or 2, wherein a joint surface of the capacitor bus bar with the connecting bus bar is parallel to a main surface of the semiconductor module.

[0109] <Technical Concept 4> The power conversion device according to any one of Technical Concepts 1 to 3, wherein a joint surface of the connecting bus bar with the power supply terminal is parallel to a main surface of the semiconductor module.

[0110] <Technical Concept 5> The power conversion device according to any one of Technical Concepts 1 to 4, wherein the plate thickness of the coupling bus bar is thinner than the plate thickness of the capacitor bus bar.

[0111] <Technical Idea 6> The power conversion device according to any one of Technical Ideas 1 to 5, wherein a first joint that is a joint between the capacitor bus bar and the connecting bus bar and a second joint that is a joint between the power supply terminal and the connecting bus bar are positioned at different positions in a direction perpendicular to a main surface of the semiconductor module.

[0112] <Technical Concept 7> The power conversion device according to Technical Concept 6, wherein the coupling bus bar includes a crank-shaped portion.

[0113] <Technical Idea 8> The power conversion device according to Technical Idea 6 or Technical Idea 7, further comprising: a circuit board (70) on which a drive circuit for the semiconductor module is formed; the bus bar unit has detection terminals (64, 65) connected to the connecting bus bar and mounted on the circuit board; and the detection terminals are provided at positions close to the capacitors in the arrangement direction of the semiconductor modules and the capacitors.

[0114] <Technical Idea 9> The power conversion device according to Technical Idea 8, wherein the detection terminal is provided at a position, in the arrangement direction, between a joint between the capacitor P bus bar and the connecting P bus bar and a joint between the capacitor N bus bar and the connecting N bus bar.

[0115] <Technical Concept 10> The power conversion device according to any one of Technical Concepts 1 to 9, wherein the capacitor has a DC terminal portion (56) connected to a portion of the capacitor bus bar that protrudes from the sealing resin body.

Claims

1. A semiconductor module (40) having a main body (41) and a power supply terminal (42) protruding from the main body; a capacitor (50) having a capacitor element (52), a sealing resin body (53) that seals the capacitor element, and a capacitor bus bar (54) that includes a portion connected to the capacitor element and a portion protruding from the sealing resin body; and a bus bar unit (60) having a connecting bus bar (61) that electrically connects the capacitor bus bar and the power supply terminal, wherein the power supply terminal includes a P terminal (42P) and an N terminal (42N), the capacitor bus bar includes a capacitor P bus bar (42P) connected to the positive electrode of the capacitor element and a capacitor N bus bar (42N) connected to the negative electrode of the capacitor element, and the connecting bus bar includes a connecting P bus bar (61P) that electrically connects the capacitor P bus bar and the P terminal, and a connecting N bus bar (61N) that electrically connects the capacitor N bus bar and the N terminal, the connecting busbars have a structure that is more easily deformed by an external force than the capacitor busbars, and the capacitor busbars are arranged so that an angle formed between a joint surface of the capacitor P busbar with the connecting P busbar and a joint surface of the capacitor N busbar with the connecting N busbar is 90 degrees or more, and a P current path section (80P) including the capacitor P busbar and the connecting P busbar, and an N current path section (80N) including the capacitor N busbar and the connecting N busbar, each have a PN parallel running section (81) in which the P current path section and the N current path section run parallel to each other, and an equipotential parallel running section (82) that is provided in one of the P current path section and the N current path section and that folds back at the joint point between the capacitor busbar and the connecting busbar.

2. The power conversion device according to claim 1, wherein the capacitor has a first insulator (55) interposed between the capacitor P bus bar and the capacitor N bus bar, the bus bar unit has a second insulator (62) interposed between the connecting P bus bar and the connecting N bus bar, and the first insulator and the second insulator overlap in at least a portion of the PN parallel running portion.

3. The power conversion device according to claim 1 or 2, wherein the joint surface of the capacitor bus bar with the connecting bus bar is parallel to the main surface of the semiconductor module.

4. The power conversion device according to claim 3, wherein the joint surface of the connecting bus bar that joins with the power supply terminal is parallel to the main surface of the semiconductor module.

5. The power conversion device according to claim 1, wherein the thickness of the connecting bus bar is thinner than the thickness of the capacitor bus bar.

6. The power conversion device according to claim 1, wherein a first joint, which is a joint between the capacitor bus bar and the connecting bus bar, and a second joint, which is a joint between the power supply terminal and the connecting bus bar, are positioned at different positions in a direction perpendicular to the main surface of the semiconductor module.

7. The power conversion device according to claim 6, wherein the connecting bus bar includes a crank-shaped portion.

8. A power conversion device as described in claim 6 or claim 7, comprising a circuit board (70) on which a drive circuit for the semiconductor module is formed, the bus bar unit having detection terminals (64, 65) connected to the connecting bus bar and mounted on the circuit board, the detection terminals being provided in a position close to the capacitor in the direction of alignment of the semiconductor module and the capacitor.

9. A power conversion device as described in claim 8, wherein the detection terminal is provided at a position in the arrangement direction between the junction between the capacitor P bus bar and the connecting P bus bar and the junction between the capacitor N bus bar and the connecting N bus bar.

10. The power conversion device according to claim 1, wherein the capacitor has a DC terminal portion (56) connected to a portion of the capacitor bus bar that protrudes from the sealing resin body.

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