Electrical circuit body and power conversion device

Abstract

This electric circuit body is provided with: a conductor plate to which semiconductor elements are joined; a cooling member that is disposed to face the conductor plate and cools heat generated by the semiconductor elements; and an insulation sheet that is disposed between the conductor plate and the cooling member. The insulation sheet includes an intermediate conductor that faces the conductor plate. The intermediate conductor is disposed to be divided into a plurality of portions with respect to the conductor plate corresponding to one of the semiconductor elements, and forms an electric capacitance that is electrically parallel to the conductor plate.

Description

Electrical circuit body and power conversion device

[0001] The present invention relates to an electric circuit body and a power conversion device.

[0002] Power conversion devices that convert DC power and AC power mutually by the switching operation of semiconductor elements have high conversion efficiency and are therefore widely used in consumer, automotive, railway, substation equipment, etc. Power conversion devices are configured by incorporating an electric circuit assembly that operates as an inverter and includes a cooling member that cools the heat generated by the semiconductor elements and an insulating sheet disposed between the semiconductor elements and the cooling member. Electric circuits used as inverters are required to be compact and lightweight, and also to have improved insulation reliability to meet the demand for higher voltages.

[0003] Patent Document 1 discloses a power module comprising a first power semiconductor element on an upper arm side and a second power semiconductor element on a lower arm side, a first conductor portion for transmitting AC current, a second conductor portion for transmitting DC current, a conductive heat dissipation portion, a first intermediate conductor layer arranged between the first conductor portion and the heat dissipation portion with an insulating layer interposed therebetween, and a second intermediate conductor layer arranged between the second conductor portion and the heat dissipation portion with an insulating layer interposed therebetween, wherein the second intermediate conductor layer is configured separately from the first intermediate conductor layer, and the first intermediate conductor layer forms a capacitance circuit that shares the voltage between the first conductor portion and the heat dissipation portion.

[0004] Japanese Patent Application Publication No. 2016-059147

[0005] The device described in Patent Document 1 has a problem with insulation reliability when high voltages are taken into consideration.

[0006] The electrical circuit body according to the present invention comprises a conductor plate to which a semiconductor element is bonded, a cooling member arranged opposite the conductor plate to cool the heat generated by the semiconductor element, and an insulating sheet arranged between the conductor plate and the cooling member, wherein the insulating sheet incorporates an intermediate conductor facing the conductor plate, and the intermediate conductor is divided into multiple pieces and arranged on the conductor plate corresponding to one of the semiconductor elements, forming an electrical capacitance that is electrically parallel to the conductor plate.

[0007] According to the present invention, the insulation reliability of the electric circuit body is improved.

[0008] 1 is a plan view of an electric circuit body. 2 is a cross-sectional view of the electric circuit body taken along line X-X. 3 is a cross-sectional view of the electric circuit body taken along line Y-Y. 4 is an enlarged cross-sectional view of the electric circuit body. 5 is a semi-transparent plan view of a semiconductor module. 6 is a circuit diagram of a semiconductor module. 7 is an enlarged cross-sectional view of an electric circuit body in Modification 1. 8 is a plan view of an insulating sheet in Modification 2. 9 is a plan view of an insulating sheet in Modification 3. 10 is a plan view of an insulating sheet in Modification 4. 11 is an enlarged cross-sectional view of an electric circuit body in Modification 5. 12 is a circuit diagram of a power conversion device using a semiconductor module. 13 is an external perspective view of the power conversion device. 14 is a cross-sectional perspective view of the power conversion device taken along line XV-XV.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] 1 is a plan view of an electric circuit body 400 according to an embodiment of the present invention. The electric circuit body 400 includes a semiconductor module 300 and a cooling member 340. In the example shown in FIG. 1, the electric circuit body 400 includes three semiconductor modules 300 arranged in parallel.

[0012] The semiconductor module 300 incorporates the semiconductor elements 155 and 157, which are sealed with a sealing material 360. Both sides of the semiconductor module 300 dissipate heat generated by the switching operation of the semiconductor elements 155 and 157. Furthermore, terminals connected to the semiconductor elements 155 and 157 are extended from the sealing material 360 on the side surfaces of the semiconductor module 300. These terminals are power terminals through which large currents flow, such as a positive terminal 325P and a negative terminal 325M connected to a capacitor module 500 (see FIG. 12) in the DC circuit, and an AC terminal 325A connected to the motor generators 192 and 194 (see FIG. 12) in the AC circuit. The semiconductor elements 155 and 157 may be switching elements such as insulated gate bipolar transistors (IGBTs) or metal-oxide semiconductor field-effect transistors (MOSFETs).

[0013] Furthermore, terminals extending from the sealing material 360 on the side surface of the semiconductor module 300 include the lower arm gate terminal 325L, the collector sense terminal 325C, the emitter sense terminal 325E, and the upper arm gate terminal 325U. These terminals extending from the semiconductor module 300 are connected to wiring such as a wiring pattern on a substrate (not shown). An electric circuit 400 having three semiconductor modules 300 arranged in parallel functions as a power conversion device 200 (see FIG. 12 ) that converts DC power and AC power mutually through the switching operation of the semiconductor elements 155, 157. The number of semiconductor modules 300 included in the electric circuit 400 is not limited to three and can be set arbitrarily to suit various configurations of the electric circuit 400.

[0014] The cooling member 340 is disposed opposite the semiconductor module 300 and cools the heat generated by the switching operation of the semiconductor elements 155, 157. Specifically, the cooling member 340 has a flow path formed therein through which a refrigerant flows, and the refrigerant flowing through the flow path cools the heat generated by the semiconductor elements 155, 157. The refrigerant used may be water or an antifreeze solution made by mixing ethylene glycol with water. The cooling member 340 is preferably made of aluminum, which has high thermal conductivity and is lightweight.

[0015] 2 and 3 are cross-sectional views of the electric circuit body 400. Fig. 2 is a cross-sectional view of the electric circuit body 400 taken along line X-X in Fig. 1. Fig. 3 is a cross-sectional view of one semiconductor module 300 taken along line Y-Y in Fig. 1.

[0016] As shown in FIG. 2, the power conversion device 200 includes an active element 155 and a diode 156 as first semiconductor elements forming the upper arm circuit (see FIGS. 5 and 6 described below). Materials such as Si, SiC, GaN, GaO, and C can be used as the active element. If a body diode of the active element 155 is used, the separate diode may be omitted. As shown in FIG. 3, the collector side of the first semiconductor element 155 is bonded to a second conductor plate 431. This bonding may be performed using solder or sintered metal. A first conductor plate 430 is bonded to the emitter side of the first semiconductor element 155.

[0017] 2 and 3, the second semiconductor element forming the lower arm circuit includes an active element 157 and a diode 158 (see FIGS. 5 and 6 described below). The collector side of the second semiconductor element 157 is bonded to a fourth conductor plate 433. The emitter side of the second semiconductor element 157 is bonded to a third conductor plate 432.

[0018] The conductor plates 430, 431, 432, and 433 are not particularly limited as long as they are made of a material with high electrical conductivity and thermal conductivity, but it is desirable to use a metal material such as a copper-based or aluminum-based material, or a composite material of a metal material and a high thermal conductivity material such as diamond, carbon, or ceramic. These may be used alone, or may be plated with Ni, Ag, or the like to improve bonding with solder or sintered metal.

[0019] In addition to carrying current, the conductor plates 430, 431, 432, and 433 also function as heat transfer members that transfer heat generated by the semiconductor elements 155, 156, 157, and 158 to the cooling member 340. The surfaces opposite to the surfaces bonded to the semiconductor elements 155, 156, 157, and 158 serve as heat dissipation surfaces for the conductor plates 430, 431, 432, and 433. Because the conductor plates 430, 431, 432, and 433 and the cooling member 340 have different potentials, an insulating sheet 443 is disposed between the heat dissipation surfaces. That is, the insulating sheet 443 serves to prevent current from passing from the conductor plates 430, 431, 432, and 433 to the cooling member 340 and other components, thereby providing electrical insulation. The insulating sheet 443 is a component that provides the main insulation for the semiconductor module 300 in the power conversion device 200.

[0020] The insulating sheet 443 covers the conductor plates 430, 431, 432, and 433 on one side and is adhered to the heat dissipation surfaces of the conductor plates 430, 431, 432, and 433. The insulating sheet 443 can be made of either organic or inorganic materials as long as it can ensure the required insulation properties. Generally, the insulating sheet 443 is called a resin insulating layer and is often made of epoxy resin, but ceramic may also be used. The method for manufacturing the insulating sheet 443 using ceramic is, for example, to sinter a green sheet, similar to that used for ceramic capacitors, and then insert a sheet-shaped electrode as the intermediate conductor 440. The use of ceramic reduces thermal degradation even when partial discharge occurs. Filler particles may be added to the insulating sheet 443 to improve thermal conductivity.

[0021] The insulating sheet 443 will be described in detail later, but the insulating sheet 443 incorporates an intermediate conductor 440 that faces the conductor plates 430, 431, 432, and 433, and the intermediate conductor 440 is divided into a plurality of conductor plates 430, 431, 432, and 433 that correspond to one of the semiconductor elements 155 and 157, and forms an electrical capacitance that is electrically parallel to the conductor plates 430, 431, 432, and 433. A surface conductor layer 444 is adhered to the other surface of the insulating sheet 443, and is exposed on the surface of the semiconductor module 300 and is in contact with the heat conduction member 453. The surface conductor layer 444 is, for example, a metal foil.

[0022] The semiconductor elements 155, 156, 157, 158, and conductor plates 430, 431, 432, and 433, together with the insulating sheet 443 and the surface conductor layer 444, are sealed with a sealing material 360 by transfer molding to form the semiconductor module 300. The sealing material 360 is often an epoxy resin, but any type of sealing material may be used as long as it has insulating properties.

[0023] The cooling members 340 are arranged on both sides of the semiconductor module 300 and are fixed to the semiconductor module 300 by fixing members not shown. Note that, although the present embodiment will be described with reference to an electric circuit body 400 in which the cooling members 340 are arranged on both sides of the semiconductor module 300, the electric circuit body 400 may also have the cooling member 340 arranged on one side of the semiconductor module 300. In this case, a housing or mounting member is arranged on the other side of the semiconductor module 300, and the other side of the semiconductor module 300 is fixed to this housing or mounting member by fixing members.

[0024] The heat conducting member 453 is disposed between the semiconductor module 300 and the cooling member 340 to reduce contact thermal resistance. The heat conducting member 453 may be made of grease, gel grease, a phase change sheet, or the like.

[0025] FIG. 4 is an enlarged cross-sectional view of the electric circuit body 400, showing portion A in FIG. 3 . As shown in FIG. 4 , the insulating sheet 443 incorporates an intermediate conductor 440 that faces the conductive plate 433. The conductive plate 433 corresponds to the semiconductor element 157 (see FIG. 3 ). The intermediate conductor 440 is divided into multiple pieces and arranged relative to the conductive plate 433. As a result, the multiple divided pieces of the intermediate conductor 440 form an electrical capacitance that is electrically parallel with the conductive plate 433. The thickness of the insulating sheet 443 is set so that the distance between the intermediate conductor 440 and the conductive plates 430, 432 or the cooling member 340 sandwiching the insulating sheet 443 does not cause partial discharge during normal operation.

[0026] The portion P where the insulating sheet 443, the sealing material 360, and the conductive plate 433 contact each other is generally referred to as a triple point from an electrical perspective. This triple point is the boundary between materials with different dielectric constants, and is therefore prone to potential concentration and requires enhanced insulation reliability. Furthermore, the triple point is prone to voids, cracks, peeling, and other voids due to the application of mechanical force, and therefore requires enhanced insulation reliability. Furthermore, in addition to the triple point, the region of the insulating sheet 443 facing the end of the conductive plate 433 is prone to peeling and other voids due to thermal stress and other factors during operation of the power conversion device 200, and therefore requires enhanced insulation reliability.

[0027] Since the insulating sheet 443 has the conductive intermediate conductor 440 built in, even if potential concentrates in the voids due to the low dielectric constant of the insulating sheet 443 when voids are generated in the insulating sheet 443, the potential concentration in the voids can be shared by the intermediate conductor 2. It is desirable that the area ratio of the intermediate conductor 440 to the cross section of the insulating sheet 443 be 20% or more.

[0028] 4, the intermediate conductor 440 is divided into a plurality of pieces of the same width and arranged at equal intervals within the insulating sheet 443. Note that the width and intervals at which the intermediate conductor 440 is divided are merely examples and can be determined as appropriate depending on the structure, configuration, and electrical characteristics of the semiconductor module 300. For example, the intermediate conductor 440 may be configured to be divided into a plurality of pieces and arranged at least in the region facing the end of the conductor plate 433.

[0029] Since the intermediate conductor 440 of the insulating sheet 443 is divided into multiple pieces, even if the intermediate conductor 440 divided by a void or the like is partially short-circuited, the entire intermediate conductor 440 will not be at the same potential, and concentration of potential on the intermediate conductor 440 other than the short-circuited portion can be suppressed.

[0030] For example, even if voids, cracks, or peeling occur at the triple junction indicated by part P due to potential concentration or mechanical force, the concentration of potential throughout the intermediate conductor 440 can be suppressed, thereby improving insulation reliability. As a result, the heat dissipation of the semiconductor module 300 can be improved and miniaturization can be achieved by thinning the insulating sheet 443 depending on the voltage value of the drive voltage. This in turn improves the insulation performance of the power conversion device 200, contributing to an increase in the output density of the power conversion device 200.

[0031] Furthermore, even if peeling or the like due to thermal stress or the like occurs in the region of the insulating sheet 443 opposite the end of the conductor plate 433, not limited to the triple point, insulation reliability can be improved by dividing the intermediate conductor 440 into multiple pieces and arranging them in this region.

[0032] 5 is a semi-transparent plan view of the semiconductor module 300. FIG.

[0033] As shown in Figures 5 and 6, the positive terminal 325P is output from the collector side of the upper arm circuit and is connected to the positive side of a battery or a capacitor. The upper arm gate terminal 325U is output from the gate of the active element 155 of the upper arm circuit. The negative terminal 325M is output from the emitter side of the lower arm circuit and is connected to the negative side of a battery or a capacitor, or GND. The lower arm gate terminal 325L is output from the gate of the active element 157 of the lower arm circuit. The AC terminal 325A is output from the collector side of the lower arm circuit and is connected to the motor. When the neutral point is grounded, the lower arm circuit is connected to the negative side of the capacitor rather than GND.

[0034] The upper arm emitter sense terminal 325E is output from the emitter of the active element 155 of the upper arm circuit, and the lower arm emitter sense terminal 325E is output from the emitter of the active element 157 of the lower arm circuit. The upper arm collector sense terminal 325C is output from the collector of the active element 155 of the upper arm circuit, and the lower arm collector sense terminal 325C is output from the collector of the active element 157 of the lower arm circuit.

[0035] Conductor plates (upper arm circuit emitter side) 430 and conductor plates (upper arm circuit collector side) 431 are arranged above and below active element 155 and diode 156 of the semiconductor element (upper arm circuit). Conductor plates (lower arm circuit emitter side) 432 and conductor plates (lower arm circuit collector side) 433 are arranged above and below active element 157 and diode 158 of the semiconductor element (lower arm circuit).

[0036] The semiconductor module 300 of this embodiment has a 2-in-1 structure in which two arm circuits, an upper arm circuit and a lower arm circuit, are integrated into a single module. Alternatively, a structure in which multiple upper arm circuits and multiple lower arm circuits are integrated into a single module may be used. In this case, the number of output terminals from the semiconductor module 300 can be reduced, thereby making the module smaller.

[0037] Fig. 7 is an enlarged cross-sectional view of an electric circuit body 400 in Modification 1, and corresponds to part A in Fig. 3, similar to Fig. 4. The same parts as in Fig. 4 are given the same reference numerals, and their description will be simplified.

[0038] 4 shows an example in which intermediate conductor 440 is divided into a plurality of pieces of the same width and arranged at equal intervals within insulating sheet 443. In Modification 1, as shown in FIG. 7 , the number of divisions of intermediate conductor 440 in the region facing the end of conductive plate 433 is greater than the number of divisions in the region facing the center of conductive plate 433.

[0039] The area of ​​the insulating sheet 443 facing the end of the conductor plate 433 is prone to peeling due to thermal stress, etc. when the power conversion device 200 is in operation, but by increasing the number of divisions of the intermediate conductor 440 in this area, the insulation reliability can be improved.

[0040] Fig. 8 is a plan view of an insulating sheet 443 in Modification 2. The intermediate conductor 440 in the insulating sheet 443 is indicated by hatching, and the peripheries of the ends of the conductor plates 430 and 432 are indicated by dashed lines. Note that although the shapes of the insulating sheet 443 and the conductor plates 430 and 432 are not the same as those shown in the semi-transparent plan view of Fig. 5, they are illustrated schematically in Fig. 8 and in Figs. 9 and 10 shown below for ease of understanding.

[0041] 8 , the divided intermediate conductors 440 with smaller areas are arranged in the portions of the insulating sheet 443 that are located around the ends of the conductor plates 430 and 432. Furthermore, the divided intermediate conductors 440 with smaller areas are arranged in the portions of the insulating sheet 443 that are located around the ends of the conductor plates 430 and 432.

[0042] According to variant example 2, even if the divided intermediate conductor 440 is partially short-circuited with either the conductor plates 430, 432 sandwiching the insulating sheet 443 or the cooling member 340, the entire intermediate conductor 440 does not become at the same potential, and concentration of potential on the intermediate conductor 440 other than the short-circuited portion can be suppressed.

[0043] FIG. 9 is a plan view of an insulating sheet 443 in Modification 3. The intermediate conductor 440 within the insulating sheet 443 is indicated by diagonal hatching, and the periphery of the edges of the conductor plates 430 and 432 is indicated by dashed lines. As shown in FIG. 9 , the intermediate conductor 440 of the insulating sheet 443 is divided into a spherical grid. The area of ​​the spheres is smaller than the area of ​​the conductor plates 430 and 432 and is determined appropriately depending on the structure, configuration, and electrical characteristics of the semiconductor module 300. Segments of the intermediate conductor 440 are appropriately arranged around the edges of the conductor plates 430 and 432. The shape is not limited to a spherical shape; elliptical, semicircular, or other shapes may be used, or a combination of these shapes may be used. Furthermore, the areas of the segments of the intermediate conductor 440 may be the same or different, regardless of whether they have the same or different shapes.

[0044] According to the third modification, it is possible to eliminate the need to design the division positions and area of ​​the intermediate conductor 440 according to the positions of the conductive plates 430 and 432. Furthermore, it is possible to improve the insulation reliability.

[0045] FIG. 10 is a plan view of the insulating sheet 443 in Modification 4. The intermediate conductor 440 within the insulating sheet 443 is indicated by diagonal hatching, and the edges of the conductor plates 430 and 432 are indicated by dashed lines. As shown in FIG. 10 , the intermediate conductor 440 of the insulating sheet 443 is divided into a diamond-shaped grid. The area of ​​the diamond shape is smaller than the area of ​​the conductor plates 430 and 432 and is determined appropriately depending on the structure, configuration, and electrical characteristics of the semiconductor module 300. Segments of the intermediate conductor 440 are appropriately arranged around the edges of the conductor plates 430 and 432. The shape is not limited to a diamond shape; it may be a triangle, a rectangle, or another polygon, or a combination of these shapes. Furthermore, the areas of the segments of the intermediate conductor 440 may be the same or different, regardless of whether they have the same or different shapes.

[0046] According to the fourth modification, it is possible to eliminate the need to design the division positions and area of ​​the intermediate conductor 440 according to the positions of the conductive plates 430 and 432. Furthermore, it is possible to improve the insulation reliability.

[0047] Fig. 11 is an enlarged cross-sectional view of an electric circuit body 400 in Modification 5, and corresponds to part A in Fig. 3, similar to Fig. 7. The same parts as in Fig. 7 are given the same reference numerals, and their description will be simplified.

[0048] 7 shows an example in which the insulating sheet 443 has one intermediate conductor 440 embedded therein in the thickness direction of the insulating sheet 443. In Modification 5, as shown in FIG. 11 , the insulating sheet 443 has two intermediate conductors 440 embedded therein in the thickness direction of the insulating sheet 443. The number of intermediate conductors is not limited to two, and multiple intermediate conductors may be provided. The distance between the intermediate conductor 440 and the conductive plates 430, 432 or cooling member 340 sandwiching the insulating sheet 443 is set to be larger than the diameter of the filler particles mixed in the insulating sheet 443.

[0049] Increasing the number of intermediate conductors 440 makes it possible to more effectively share the potential between the intermediate conductors 440 and either the conductive plates 430 and 432 sandwiching the insulating sheet 443 or the cooling member 340. This makes it possible to provide multiple protection in the event of a short circuit.

[0050] FIG. 12 is a circuit diagram of a power conversion device 200 using a semiconductor module 300. The power conversion device 200 includes inverter circuits 140 and 142, an auxiliary inverter circuit 43, and a capacitor module 500. The inverter circuits 140 and 142 include multiple semiconductor modules 300, which are connected to form a three-phase bridge circuit. For larger current capacities, additional semiconductor modules 300 can be connected in parallel, corresponding to each phase of the three-phase inverter circuit. The current capacity can also be increased by connecting active elements 155 and 157 and diodes 156 and 158, which are semiconductor elements built into the semiconductor module 300, in parallel.

[0051] The inverter circuit unit 140 and the inverter circuit unit 142 have the same basic circuit configuration, and also have the same control method and operation. The outline of the circuit operation of the inverter circuit unit 140 and the like is well known, so a detailed description will be omitted here.

[0052] The upper arm circuit includes, as switching semiconductor elements, an upper arm active element 155 and an upper arm diode 156, and the lower arm circuit includes, as switching semiconductor elements, a lower arm active element 157 and a lower arm diode 158. Active elements 155 and 157 perform switching operations in response to drive signals output from one or the other of two driver circuits that make up driver circuit 174, and convert DC power supplied from battery 136 into three-phase AC power.

[0053] The upper arm active element 155 and the lower arm active element 157 each have a collector electrode, an emitter electrode, and a gate electrode. The upper arm diode 156 and the lower arm diode 158 each have two electrodes: a cathode electrode and an anode electrode. As shown in FIG. 6 , the cathode electrodes of the diodes 156 and 158 are electrically connected to the collector electrodes of the active elements 155 and 157, and the anode electrodes are electrically connected to the emitter electrodes of the active elements 155 and 157, respectively. As a result, the current flows in the forward direction from the emitter electrode to the collector electrode of the upper arm active element 155 and the lower arm active element 157. The active elements 155 and 157 are, for example, IGBTs.

[0054] It should be noted that a MOSFET may be used as the active element, in which case the upper arm diode 156 and the lower arm diode 158 are not required.

[0055] The positive terminal 325P and the negative terminal 325M of each upper and lower arm series circuit are each connected to a DC terminal for connecting a capacitor of the capacitor module 500. AC power is generated at the connection between the upper arm circuit and the lower arm circuit, and the connection between the upper arm circuit and the lower arm circuit of each upper and lower arm series circuit is connected to the AC terminal 325A of each semiconductor module 300. The AC terminal 320B of each semiconductor module 300 of each phase is each connected to the AC output terminal of the power conversion device 200, and the generated AC power is supplied to the stator winding of the motor generator 192 or 194.

[0056] The control circuit 172 generates timing signals for controlling the switching timing of the upper arm active element 155 and the lower arm active element 157 based on input information from a vehicle-side control device, a sensor (e.g., a current sensor 180), etc. The driver circuit 174 generates drive signals for performing switching operations on the upper arm active element 155 and the lower arm active element 157 based on the timing signals output from the control circuit 172. Note that reference numerals 181 and 188 denote connectors.

[0057] The upper and lower arm series circuits each include a temperature sensor (not shown), and temperature information about the upper and lower arm series circuits is input to the microcomputer. Information about the DC positive voltage of the upper and lower arm series circuits is also input to the microcomputer. The microcomputer detects overtemperature and overvoltage based on this information, and if an overtemperature or overvoltage is detected, the microcomputer stops the switching operation of all upper arm active elements 155 and lower arm active elements 157, thereby protecting the upper and lower arm series circuits from overtemperature or overvoltage.

[0058] 13 is an external perspective view of the power conversion device 200 shown in FIG. 12, and FIG. 14 is a cross-sectional perspective view of the power conversion device 200 shown in FIG. 13 taken along line XV-XV.

[0059] The power conversion device 200 includes a housing 12 formed into a substantially rectangular parallelepiped shape and composed of a lower case 11 and an upper case 10. The housing 12 accommodates an electric circuit body 400, a capacitor module 500, and the like. The electric circuit body 400 has a cooling flow path leading to a cooling member 340, and a refrigerant inlet pipe 13 and a refrigerant outlet pipe 14 communicating with the cooling flow path protrude from one side of the housing 12. The lower case 11 has an opening at the top, and the upper case 10 is attached to the lower case 11, closing the opening. The upper case 10 and the lower case 11 are formed of an aluminum alloy or the like and are fixed in place while being sealed from the outside. The upper case 10 and the lower case 11 may be integrally formed. The housing 12 has a simple rectangular parallelepiped shape, which facilitates installation in a vehicle or the like and also facilitates production.

[0060] A connector 17 is attached to one longitudinal side surface of the housing 12, and an AC terminal 18 is connected to this connector 17. A connector 21 is provided on the surface from which the refrigerant inlet pipe 13 and the refrigerant outlet pipe 14 are led out.

[0061] As shown in FIG. 14 , an electric circuit body 400 is housed within the housing 12. The control circuit 172 and the driver circuit 174 are disposed within the electric circuit body 400, and a capacitor module 500 is housed on the DC terminal side of the electric circuit body 400. By arranging the capacitor module at the same height as the electric circuit body 400, the power conversion device 200 can be made thinner, improving the degree of freedom in installation in a vehicle. The AC side terminal 325A of the electric circuit body 400 passes through the current sensor 180 and is connected to the connector 188. In addition, the positive side terminal 325P and the negative side terminal 325M, which are DC terminals of the semiconductor module 300, are joined to the positive and negative terminals 362A and 362B of the capacitor module 500, respectively.

[0062] According to the embodiment described above, the following effects can be obtained: (1) The electric circuit body 400 includes the conductor plates 430, 431, 432, and 433 to which the semiconductor elements 155, 156, 157, and 158 are joined, the cooling member 340 that is disposed opposite the conductor plates 430, 431, 432, and 433 and that cools the heat generated by the semiconductor elements 155, 156, 157, and 158, and the insulating sheet 340 that is disposed between the conductor plates 430, 431, 432, and 433 and the cooling member 340. The insulating sheet 443 incorporates an intermediate conductor 440 that faces the conductor plates 430, 431, 432, and 433, and the intermediate conductor 440 is divided into a plurality of pieces and arranged for the conductor plates 430, 431, 432, and 433 that correspond to one of the semiconductor elements 155, 156, 157, and 158, forming an electric capacitance that is electrically parallel to the conductor plates 430, 431, 432, and 433. This improves the insulation reliability of the electric circuit body.

[0063] The present invention is not limited to the above-described embodiment, and other forms that can be conceived within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as they do not impair the characteristics of the present invention. Furthermore, a configuration that combines the above-described embodiment with multiple modified examples may also be used.

[0064] 10: Upper case, 11: Lower case, 13: Refrigerant inlet pipe, 14: Refrigerant outlet pipe, 17, 21, 181, 182, 188: Connector, 18: AC terminal, 43, 140, 142: Inverter circuit, 155, 156, 157, 158: Semiconductor element, 172: Control circuit, 174: Driver circuit, 180: Current sensor, 192, 194: Motor generator, 200: Power conversion device, 300: Semiconductor module, 310: Circuit body, 32 5P: Positive terminal, 325M: Negative terminal, 325A: AC terminal, 325C: Collector sense terminal, 325L: Lower arm gate terminal, 325E: Emitter sense terminal, 325U: Upper arm gate terminal, 340: Cooling member, 360: Sealing material, 400: Electrical circuit body, 430, 431, 432, 433: Conductive plate, 440: Intermediate conductor, 443: Insulating sheet, 444: Surface conductor layer, 453: Heat conduction member, 500: Capacitor module.

Claims

1. An electrical circuit comprising: a conductor plate to which a semiconductor element is bonded; a cooling member disposed opposite the conductor plate for cooling heat generated by the semiconductor element; and an insulating sheet disposed between the conductor plate and the cooling member, wherein the insulating sheet incorporates an intermediate conductor facing the conductor plate, the intermediate conductor being divided into a plurality of pieces and disposed on the conductor plate corresponding to one of the semiconductor elements, and forming an electrical capacitance that is electrically parallel to the conductor plate.

2. An electric circuit as claimed in claim 1, wherein the intermediate conductor is divided into a plurality of pieces and arranged in a region facing the end of the conductive plate.

3. An electric circuit body according to claim 1, wherein the number of divisions of the intermediate conductor in the area facing the end portion of the conductive plate is greater than the number of divisions of the area facing the center portion of the conductive plate.

4. An electric circuit as claimed in claim 1, wherein said intermediate conductor is divided into a lattice pattern.

5. An electric circuit body according to claim 1, wherein the insulating sheet incorporates a plurality of the intermediate conductors in the thickness direction of the insulating sheet.

6. The electric circuit according to claim 1, wherein the insulating sheet is made of ceramic.

7. An electric circuit as claimed in claim 1, wherein the area of ​​said insulating sheet occupied by said intermediate conductor is 20% or more of the cross section of said insulating sheet.

8. An electric circuit body as claimed in any one of claims 1 to 7, wherein the conductor plates are formed on both sides of the semiconductor element, the cooling members are arranged on both sides facing each of the conductor plates, and the insulating sheets are respectively arranged between the conductor plates and the cooling members.

9. A power conversion device comprising the electric circuit body according to any one of claims 1 to 7, for converting DC power and AC power mutually.

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