Power conversion device

Abstract

A power conversion device (1) comprises: an electronic component having a body portion that is a heating element, a first electrode electrically connected to one side of the body portion, and a second electrode electrically connected to the other side of the body portion, wherein the first electrode, the body portion, and the second electrode are stacked in this order; and a cooler (2) that cools the electronic component. The first electrode has a first electrode body portion connected to the body portion and a first connection terminal connected to the first electrode body portion. The second electrode has a second electrode body portion connected to the body portion and a second connection terminal connected to the second electrode body portion. When the heat conduction from the first electrode to the cooler (2) is greater than the heat conduction from the second electrode to the cooler (2), the cross-sectional area of the second connection terminal is greater than the cross-sectional area of the first connection terminal. When the heat conduction from the second electrode to the cooler (2) is greater than the heat conduction from the first electrode to the cooler (2), the cross-sectional area of the first connection terminal is greater than the cross-sectional area of the second connection terminal.

Description

Power Conversion Device

[0001] The present disclosure relates to a power conversion device.

[0002] Electrically powered vehicles that use a motor as a drive source, such as hybrid vehicles, plug-in hybrid vehicles, electric vehicles, and fuel cell vehicles, are equipped with power conversion devices, such as an inverter for driving the drive motor and a converter for increasing or decreasing the power supply voltage of the battery. To ensure sufficient trunk and passenger space inside the electric vehicle, the power conversion device must be installed in a limited space, and therefore, the power conversion device must be a small component. Furthermore, since the power conversion device installed in the vehicle is connected to a heat source such as the engine, transmission, or motor, it must have high heat resistance.

[0003] Power conversion devices such as inverters and converters often include a capacitor with a capacitor element that smooths the DC current supplied from an external DC power source. A capacitor is one of the electronic components included in a power conversion device. Ripple current flows through a capacitor, causing the capacitor to consume power and generate heat. Furthermore, because the capacitor is connected to other components via a bus bar, heat is transferred from the other components to the capacitor via the bus bar, which can cause the capacitor to become too hot. Since a rise in capacitor temperature shortens the lifespan of the capacitor element, measures to prevent this temperature rise are a key issue.

[0004] A configuration that takes measures to prevent the temperature rise of the capacitor has been disclosed (see, for example, Patent Document 1). In the structure disclosed in Patent Document 1, the thermal resistance of the bus bar at the point where it is connected to the capacitor is increased. This configuration reduces the amount of heat transferred from the bus bar to the capacitor, thereby suppressing the temperature rise of the capacitor.

[0005] Japanese Patent Application Laid-Open No. 2022-128162

[0006] In the above-mentioned Patent Document 1, the thermal resistance of the busbar at the portion connected to the capacitor is increased, thereby suppressing the temperature rise of the capacitor. However, the high thermal resistance of the busbar at the portion connected to the capacitor makes it difficult to cool the capacitor via the busbar. Furthermore, although the transfer of heat from the busbar to the capacitor can be suppressed, if the busbar itself generates a lot of heat, the heat from the busbar can cause the capacitor to become too hot.

[0007] Therefore, an object of the present disclosure is to obtain a power conversion device that suppresses temperature rise of electronic components while maintaining a small size.

[0008] The power conversion device of the present disclosure includes a main body portion that is a heat generating body, a first electrode electrically connected to one side of the main body portion, and a second electrode electrically connected to the other side opposite to the one side of the main body portion, and is equipped with electronic components stacked in the order of the first electrode, main body portion, and second electrode, and a cooler that cools the electronic components, and the first electrode has a first electrode main body portion connected to the main body portion and a first connection terminal connected to the first electrode main body portion and connected to another component on the side opposite to the side of the first electrode main body portion, and the second electrode has a second electrode main body portion connected to the main body portion and a second connection terminal connected to the second electrode main body and has a second connection terminal connected to another component on the side opposite to the second electrode main body, and when the thermal conduction from the first electrode to the cooler is greater than the thermal conduction from the second electrode to the cooler, the cross-sectional area of ​​the second connection terminal in a direction perpendicular to the current flow is greater than the cross-sectional area of ​​the first connection terminal in a direction perpendicular to the current flow, and when the thermal conduction from the second electrode to the cooler is greater than the thermal conduction from the first electrode to the cooler, the cross-sectional area of ​​the first connection terminal in a direction perpendicular to the current flow is greater than the cross-sectional area of ​​the second connection terminal in a direction perpendicular to the current flow.

[0009] According to the power conversion device disclosed herein, when the thermal conduction from the first electrode to the cooler is greater than the thermal conduction from the second electrode to the cooler, the cross-sectional area of ​​the second connection terminal in a direction perpendicular to the current flow is larger than the cross-sectional area of ​​the first connection terminal in a direction perpendicular to the current flow. Also, when the thermal conduction from the second electrode to the cooler is greater than the thermal conduction from the first electrode to the cooler, the cross-sectional area of ​​the first connection terminal in a direction perpendicular to the current flow is larger than the cross-sectional area of ​​the second connection terminal in a direction perpendicular to the current flow. Therefore, without adding any new components, the amount of heat generated by the first connection terminal of the first electrode or the second connection terminal of the second electrode, which has low thermal conduction to the cooler and is therefore difficult to cool, is reduced, thereby reducing the amount of heat transferred to the electronic components. This reduces the amount of heat transferred to the electronic components, thereby achieving a power conversion device that suppresses temperature increases while maintaining a compact size. Furthermore, when the temperature of another component connected via the first connection terminal and the second connection terminal is lower than that of the electronic components, the first connection terminal or the second connection terminal has a portion with a large cross-sectional area, allowing the heat from the electronic components to be efficiently dissipated to the other components. Furthermore, heat transferred from the outside to the electronic component via the air or the like can also be efficiently dissipated to other components via the first connection terminal or the second connection terminal.

[0010] 14 is a plan view showing an outline of a power converter according to embodiment 1. FIG. 1 is a cross-sectional view of the power converter taken along the A-A cross section of FIG. 1. FIG. 1 is a cross-sectional view of a main part of a power converter taken along the B-B cross section of FIG. 1. FIG. 1 is a cross-sectional view of a main part of another power converter taken along the B-B cross section of FIG. 1. FIG. 1 is a diagram showing an example of an installation state of a power converter according to embodiment 1. FIG. 15 is a plan view showing an outline of a power converter according to embodiment 2. FIG. 16 is a plan view showing an outline of a positive bus bar of the power converter according to embodiment 2. FIG. 17 is a cross-sectional view of the power converter taken along the CC cross section of FIG. 6, which is a side view showing an outline of the positive bus bar of the power converter according to embodiment 2. FIG. 18 is a plan view showing an outline of a power converter according to embodiment 3. FIG. 19 is a cross-sectional view of the power converter taken along the D-D cross section of FIG. 10. FIG. 19 is a cross-sectional view of a main part of the power converter taken along the E-E cross section of FIG. 10. FIG. 20 is a cross-sectional view showing an outline of a power converter according to embodiment 4. FIG. 21 is a side view showing an outline of a rapid discharge resistor of the power converter according to embodiment 4. FIG. 22 is a cross-sectional view of a main part of the rapid discharge resistor taken along the F-F cross section of FIG. Fig. 16 is a cross-sectional view showing an outline of a substrate of a power converter according to embodiment 5. Fig. 17 is a cross-sectional view of the substrate of the power converter taken along the line G-G in Fig. 16.

[0011] Hereinafter, a power conversion device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the same or equivalent members and parts in each drawing will be denoted by the same reference numerals.

[0012] Embodiment 1. Fig. 1 is a plan view showing an outline of a power conversion device 1 according to embodiment 1, with the substrate 5 removed, Fig. 2 is a cross-sectional view of the power conversion device 1 taken along the A-A cross section of Fig. 1, Fig. 3 is a cross-sectional view of a terminal 45 for connecting other components, which is a main part of the power conversion device 1, taken along the B-B cross section of Fig. 1, Fig. 4 is a cross-sectional view of a terminal 45 for connecting other components, which is a main part of another power conversion device 1, taken along the B-B cross section of Fig. 1, and Fig. 5 is a diagram showing an example of an installation state of the power conversion device 1. The power conversion device 1 is a device that converts an input current from DC to AC, AC to DC, or an input voltage to a different voltage.

[0013] As shown in FIG. 2 , the power conversion device 1 includes a semiconductor module 3, a capacitor 4, a substrate 5, a rapid discharge resistor 6 (not shown in FIGS. 1 and 2 ), and a cooler 2. The cooler 2 houses the semiconductor module 3, the capacitor 4, the substrate 5, and the rapid discharge resistor 6. The power conversion device 1 in this embodiment is a device that converts DC power input from the other component connection terminal 45 of the capacitor 4 connected to a DC power source 7 and smoothes it in the capacitor 4, and outputs the converted power using the semiconductor module 3. This embodiment shows a power conversion device 1 that outputs three-phase AC, and as shown in FIG. 1 , the semiconductor module is composed of three semiconductor modules 3 corresponding to each phase. The configuration of the power conversion device 1 is not limited to this, and the power conversion device 1 may also be a device that converts input current from AC to DC.

[0014] <Cooler 2> The cooler 2 is made of metal such as aluminum. As shown in FIG. 2, the cooler 2 is formed, for example, in the shape of a cylinder with a bottom. The cooler 2 has a first surface 2b to which the semiconductor module 3 is thermally connected and a second surface 2c parallel to the first surface 2b and to which the capacitor 4 is thermally connected. A plate-shaped forced cooling section 21 is provided in the portion of the cooler 2 where the first surface 2b is formed. A flow path 22 for cooling the first surface 2b is provided on the rear surface of the rear side of the forced cooling section 21. One surface, or the front surface, of the forced cooling section 21 is the first surface 2b. The portion of the cooler 2 where the flow path 22 is provided is a flow path forming section 23. The flow path forming section 23 is provided on the other surface of the forced cooling section 21. A refrigerant flows through the flow path 22. For example, a liquid such as water or ethylene glycol liquid, or a gas such as air, is used as the refrigerant. Directions are defined here. A direction opposite to the normal direction of the first surface 2b is defined as the anti-normal direction, a specific direction parallel to the first surface 2b is defined as the first direction, and a direction parallel to the first surface 2b and perpendicular to the first direction is defined as the second direction. In the figure, the X1 direction is one side of the first direction, the X2 direction is the other side of the first direction, the Y direction is the second direction, the Z1 direction is the normal direction, and the Z2 direction is the anti-normal direction.

[0015] The forced cooling unit 21 is made of, for example, a metal such as aluminum, like the main body of the cooler 2, but is not limited to this and may be made of a resin material with excellent thermal conductivity. A plurality of cooling fins may be provided on the back surface of the forced cooling unit 21 in an area that overlaps with the semiconductor module 3 when viewed in the normal direction. As shown in FIG. 1 , the flow path forming unit 23 has refrigerant inlets and outlets 24a, 24b. The refrigerant inlets and outlets 24a, 24b are inlets and outlets through which the refrigerant flows into or out of the flow path 22. The refrigerant inlets and outlets 24a, 24b have portions that protrude from the outer wall surface of the cooler 2.

[0016] The refrigerant flows, for example, through the refrigerant inlet / outlet 24a, the flow path 22, and the refrigerant inlet / outlet 24b in this order. When viewed in the normal direction, the refrigerant inlet / outlet 24a is located closer to the condenser 4 than the refrigerant inlet / outlet 24b. With this configuration, low-temperature refrigerant before cooling the semiconductor modules 3 flows on the side of the refrigerant inlet / outlet 24a, so that the second surface 2c located adjacent to the first surface 2b is also efficiently cooled. Because the second surface 2c is cooled, the condenser 4 thermally connected to the second surface 2c can be cooled.

[0017] As shown in FIG. 2 , the second surface 2c faces the normal direction and is disposed on one side of the first surface 2b in the first direction, opposite the normal direction from the first surface 2b. The cooler has a step 2a between the first surface 2b and the second surface 2c. The flow path 22 is disposed on the other side of the step 2a in the first direction. This configuration allows the step 2a to be provided so that the positive power terminal 42a1 and the negative power terminal 42b1 of the capacitor bus bar 42 protruding from the capacitor 4 are aligned with the semiconductor module bus bar 33 protruding from the semiconductor module 3 in the normal direction. This allows the length of the capacitor bus bar 42 to be shortened. The shortened length of the capacitor bus bar 42 allows the capacitor element 41 and the semiconductor module 3 to be connected with low wiring inductance, thereby suppressing excess loss in the capacitor bus bar 42 connecting the capacitor element 41 and the semiconductor module 3.

[0018] Furthermore, since flow path 22 is disposed in the surplus space on the opposite side of first surface 2b in the normal direction and on the other side of step 2a in the first direction, the height of power conversion device 1 is reduced, thereby enabling a reduction in the size of power conversion device 1. Furthermore, since both refrigerant inlets and outlets 24a, 24b are arranged on the other side of step 2a in the first direction, it is possible to reduce the size of power conversion device 1. Furthermore, since refrigerant inlet and outlet 24b is passed through by refrigerant heated by heat from semiconductor module 3, refrigerant inlet and outlet 24b is disposed at a position away from condenser 4, and refrigerant inlet and outlet 24a is disposed on the side closer to condenser 4, condenser 4 can be cooled efficiently.

[0019] <Semiconductor Module 3> The semiconductor module 3 includes a module body 3a housing one or more semiconductor elements 31, a semiconductor module bus bar 33, an output terminal 38, and multiple control terminals (not shown). The semiconductor module bus bar 33, the output terminal 38, and the control terminals protrude outward from the module body 3a. The portion of the module body 3a shown in FIG. 1 is a sealing resin 35 surrounding the semiconductor elements 31. The semiconductor module bus bar 33, the output terminal 38, and the control terminals are made of, for example, copper, which has low electrical resistivity and excellent conductivity. The semiconductor module bus bar 33 includes a positive bus bar 33a and a negative bus bar 33b, and the capacitor bus bar 42 includes a positive bus bar 42a and a negative bus bar 42b. The positive bus bar 33a is electrically connected to the positive power terminal 42a1 of the positive bus bar 42a, and the negative bus bar 33b is electrically connected to the negative power terminal 42b1 of the negative bus bar 42b. The number of semiconductor elements 31 may be one or more.

[0020] <Substrate 5> The power conversion device 1 includes a substrate 5 on which a control circuit that controls the semiconductor module 3 is mounted. The substrate 5 and the semiconductor module 3 are connected by a plurality of control terminals (not shown) that the semiconductor module 3 has. The substrate 5 is provided on the normal direction side of the capacitor 4 and the semiconductor module 3. The substrate 5 is arranged so as to cover at least a portion of each of the capacitor 4 and the semiconductor module 3 when viewed in the normal direction.

[0021] <Electronic Components> The power conversion device 1 has a heat-generating body and electronic components that generate heat during operation. The cooler 2 cools the electronic components. The electronic component included in the power conversion device 1 in this embodiment is a capacitor 4. The electronic component is not limited to the capacitor 4. Examples in which the power conversion device 1 includes electronic components other than the capacitor 4 will be described later.

[0022] The electronic component includes a main body portion that is a heat generating body, a first electrode electrically connected to one side of the main body portion, and a second electrode electrically connected to the other side opposite the one side of the main body portion, and the first electrode, the main body portion, and the second electrode, are stacked in this order. The first electrode has a first electrode main body portion connected to the main body portion and a first connection terminal connected to the first electrode main body portion and connected to another component on the side opposite the first electrode main body portion. The second electrode has a second electrode main body portion connected to the main body portion and a second connection terminal connected to the second electrode main body portion and connected to another component on the side opposite the second electrode main body portion. When thermal conduction from the first electrode to the cooler 2 is greater than thermal conduction from the second electrode to the cooler 2, the cross-sectional area of ​​the second connection terminal in a direction perpendicular to the current flow is larger than the cross-sectional area of ​​the first connection terminal in a direction perpendicular to the current flow. When thermal conduction from the second electrode to the cooler 2 is greater than thermal conduction from the first electrode to the cooler 2, the cross-sectional area of ​​the first connection terminal in a direction perpendicular to the current flow is larger than the cross-sectional area of ​​the second connection terminal in a direction perpendicular to the current flow.

[0023] By configuring in this manner, the amount of heat generated by the first connection terminal of the first electrode or the second connection terminal of the second electrode, which have low thermal conductivity to the cooler 2 and are difficult to cool, is reduced without adding any new components, thereby reducing the amount of heat transferred to the electronic components. Because the amount of heat transferred to the electronic components is reduced without adding any new components, a power conversion device can be obtained that suppresses temperature increases in the electronic components while maintaining a compact size. Furthermore, when the temperature of other components connected via the first connection terminal and the second connection terminal is lower than that of the electronic components, the first connection terminal or the second connection terminal has a portion with a large cross-sectional area, allowing the heat from the electronic components to be efficiently dissipated to the other components. Furthermore, heat transferred from the outside to the electronic components via air or the like can also be efficiently dissipated to the other components via the first connection terminal or the second connection terminal.

[0024] <Capacitor 4> The capacitor 4, which is an electronic component, will be described in detail below. The capacitor 4 has one or more capacitor elements 41 and capacitor bus bars 42 connected to the capacitor elements 41, which are a positive bus bar 42a and a negative bus bar 42b. The main body of the electronic component is one or more capacitor elements 41, with the first electrode being the positive bus bar 42a and the second electrode being the negative bus bar 42b. The first electrode may be the negative bus bar 42b and the second electrode may be the positive bus bar 42a. The capacitor 4 further has a case 44 that houses the capacitor element 41, the positive bus bar 42a, and the negative bus bar 42b. The case 44 is filled with a sealing resin 43. The sealing resin 43 is an insulating member made of epoxy resin or the like.

[0025] The capacitor element 41 smoothes the DC power. The capacitor element 41 has electrodes 48 on both ends. Each of the electrodes 48 is a positive electrode 48a or a negative electrode 48b. In this embodiment, the positive electrode 48a is provided on the normal side of the capacitor element 41, and the negative electrode 48b is provided on the opposite side to the normal side. However, this is not limiting, and the negative electrode 48b may be provided on the normal side and the positive electrode 48a on the opposite side to the normal side.

[0026] Capacitor element 41 is a film capacitor having a laminated structure in which metal foil and resin film serving as internal electrodes are wound into a roll. Capacitor element 41 has electrodes 48 on end faces in a normal direction and an opposite direction to the normal direction, which intersects with a first direction in which the metal foil is laminated. Since film capacitors generally have a higher withstand voltage than other types of capacitors, using a film capacitor for capacitor element 41 allows power conversion device 1 to be used in vehicles where high withstand voltage is required.

[0027] In this embodiment, the case 44 houses three capacitor elements 41. In Fig. 1, the outline of the capacitor elements 41 is indicated by a dashed line. Each of the three capacitor elements 41 is connected to each of the three semiconductor modules 3. The number of capacitor elements 41 included in the capacitor 4 is not limited to three. A single capacitor element 41 may be connected to a plurality of semiconductor modules 3, or a plurality of capacitor elements 41 may be connected to a single semiconductor module 3.

[0028] The case 44 is made of aluminum by die-casting, for example. In this embodiment, as shown in FIG. 2 , the case 44 is formed in a cylindrical shape with a bottom. The bottom wall 44 a of the case 44 is formed in a rectangular shape, for example. The case 44 has an opening 49, which is an open portion on the side opposite the bottom wall 44 a of the case 44. The opening 49 faces the substrate 5. The capacitor bus bar 42 protrudes from the sealing resin 43 at the opening 49. In this embodiment, the case 44 is arranged so that the opening 49 faces the normal direction, and the capacitor bus bar 42 protrudes from the sealing resin 43 in the normal direction. The arrangement of the case 44 is not limited thereto. As will be described later, the case 44 may be arranged so that the opening 49 faces the other side of the first direction, so that the capacitor bus bar 42 protrudes from the sealing resin 43 toward the semiconductor module 3.

[0029] The outer surface of the bottom wall 44a of the case 44 is thermally connected to the second surface 2c of the cooler 2. The thermal connection is not limited to a case where the bottom wall 44a and the second surface 2c are connected through direct contact. The bottom wall 44a and the second surface 2c may also be thermally connected via a heat transfer member such as grease or a heat dissipation sheet. By thermally connecting the case 44 to the cooler 2, the capacitor element 41 can dissipate heat from the bottom wall 44a side of the case 44, thereby improving the heat dissipation performance of the capacitor element 41.

[0030] The capacitor bus bar 42 is made of, for example, copper, which has low electrical resistivity and excellent conductivity. The positive bus bar 42a has a first electrode main body 42c1 connected to the positive electrode 48a of the capacitor element 41 and a first connection terminal 45a connected to the first electrode main body 42c1 and connected to another component on the side opposite the first electrode main body 42c1. The negative bus bar 42b has a second electrode main body 42c2 connected to the negative electrode 48b of the capacitor element 41 and a second connection terminal 45b connected to the second electrode main body 42c2 and connected to another component on the side opposite the second electrode main body 42c2. The first connection terminal 45a and the second connection terminal 45b connected to the other component are other-component connection terminals 45. The direction of current flow (current path 8) through the first connection terminal 45a and the second connection terminal 45b is a first direction. The other component is, for example, a DC power supply 7. The first electrode main body portion 42c1 of the positive bus bar 42a is provided on the opening 49 side, and the second electrode main body portion 42c2 of the negative bus bar 42b is provided on the bottom wall 44a side. In the present embodiment, the first electrode main body portion 42c1 is connected to three capacitor elements 41, and the second electrode main body portion 42c2 is connected to three capacitor elements 41. The number of capacitor elements 41 to which each of the first electrode main body portion 42c1 and the second electrode main body portion 42c2 is connected is not limited to this.

[0031] The thermal conductivity of the metal foil in the film capacitor is higher than that of the resin film. Therefore, the thermal conductivity of the capacitor element 41 is higher in a direction intersecting the metal foil lamination direction (the axial direction of the winding core) than in the first direction, which is the direction in which the metal foil is laminated. When the electrode 48 and the bottom wall 44a are arranged in the direction opposite the normal, as in this embodiment, the thermal conductivity of the capacitor element 41 is higher in the direction opposite the normal. Therefore, by aligning the direction of high thermal conductivity of the capacitor element 41 with the direction of the heat dissipation path in which the bottom wall 44a of the case 44 is arranged, the heat of the capacitor element 41 can be more efficiently dissipated to the bottom wall 44a of the case 44.

[0032] In this embodiment, the substrate 5 is disposed on the normal side of the capacitor 4. This is to facilitate electrical connection between the substrate 5 and the positive bus bar 42a. The portion of the positive bus bar 42a that connects to the substrate 5 is the substrate connection terminal 42a2. The positive bus bar 42a extends from the first electrode main body portion 42c1 toward the semiconductor module 3 and has a positive power terminal 42a1 connected to the semiconductor module 3. Similarly, the negative bus bar 42b extends from the second electrode main body portion 42c2 toward the semiconductor module 3 and has a negative power terminal 42b1 connected to the semiconductor module 3. The substrate connection terminal 42a2 extends in the normal direction from the positive power terminal 42a1 and is connected to the substrate 5. The substrate connection terminal 42a2 is a terminal on the substrate 5 that is connected to a driver circuit that supplies power to the semiconductor module 3.

[0033] In this embodiment, the positive bus bar 42a is provided on the side of the opening 49, and the negative bus bar 42b is provided on the side of the bottom wall 44a that is thermally connected to the cooler 2. Therefore, the distance over which heat is transferred to the cooler 2 differs between the positive and negative sides of the capacitor 4. When the amount of heat transferred from the positive bus bar 42a to the cooler 2 is compared with the amount of heat transferred from the negative bus bar 42b to the cooler 2, the negative bus bar 42b, which is closer to the cooler 2 and has lower thermal resistance with respect to the cooler 2, transfers more heat than the positive bus bar 42a. When the capacitor 4 is a film capacitor, the thermal conductivity of the resin is dominant because the film capacitor is made of a thin metal foil and a resin film. Therefore, the equivalent thermal conductivity of the capacitor element 41 is low, and if the capacitor bus bar 42 generates a large amount of heat and the capacitor element 41 receives a large amount of heat from the capacitor bus bar 42, the heat cannot be sufficiently dissipated to the cooler 2, and there is a risk that the capacitor element 41 will become too hot.

[0034] Furthermore, the first electrode main body 42c1 and the second electrode main body 42c2 are electrically connected to the plurality of capacitor elements 41 within the case 44 and therefore extend in the second direction in which the capacitor elements 41 are arranged. Meanwhile, the other component connection terminal 45 is formed on a portion of the capacitor bus bar 42 that protrudes from the case 44 and is smaller than the first electrode main body 42c1 and the second electrode main body 42c2 in order to reduce the size of the power conversion device 1 and ensure space for arranging other components. Therefore, the other component connection terminal 45 generates more heat than the first electrode main body 42c1 and the second electrode main body 42c2. Heat generated in the other component connection terminal 45 is transferred to the capacitor elements 41 via the first electrode main body 42c1 and the second electrode main body 42c2, which are made of copper, which has high thermal conductivity, and this may cause the capacitor elements 41 to become too hot.

[0035] 3 , in the present embodiment, the cross-sectional area of ​​the first connection terminal 45a of the positive bus bar 42a, which transfers less heat to the cooler 2 and is therefore less likely to be cooled, is larger than the cross-sectional area of ​​the second connection terminal 45b of the negative bus bar 42b. This reduces the amount of heat generated by the first connection terminal 45a, thereby reducing the amount of heat transferred to the capacitor element 41. Because the amount of heat transferred to the capacitor element 41 is reduced, it is possible to suppress a rise in the temperature of the capacitor 4. Furthermore, because the capacitor element 41, the positive bus bar 42a, and the negative bus bar 42b are housed in the case 44, the productivity of the power conversion device 1 can be improved.

[0036] When the capacitor bus bar 42 is manufactured from a single copper plate, it is difficult to increase the thickness of only the component connection terminals 45. Furthermore, because the component connection terminals 45 are joined to the other component by screwing or welding, the component connection terminals 45 require a joining area, and therefore a certain area or more must be secured for the component connection terminals 45. In this embodiment, the first connection terminals 45a of the positive bus bar 42a and the second connection terminals 45b of the negative bus bar 42b have the same thickness, but the first connection terminals 45a of the positive bus bar 42a and the second connection terminals 45b of the negative bus bar 42b have different widths in the direction perpendicular to the current flow. Being equal means that the design lengths are the same, and the difference in length is within the tolerance range and within the range of manufacturing error.

[0037] This configuration allows the cross-sectional areas of the first connection terminal 45a and the second connection terminal 45b to be different while maintaining the same thickness. In the configuration shown in FIG. 3 , the cross-sectional area of ​​the first connection terminal 45a is larger than that of the second connection terminal 45b, reducing the amount of heat generated by the first connection terminal 45a. In FIG. 3 , the direction of current flow is perpendicular to the paper. Increasing the width of only the first connection terminal 45a and keeping the width of the second connection terminal 45b small allows the capacitor 4 to be more compact than when both the positive bus bar 42a and the negative bus bar 42b are increased in width. While the amount of heat generated by the second connection terminal 45b is greater than that of the first connection terminal 45a, the negative bus bar 42b is located close to the cooler 2, resulting in a large amount of heat transfer to the cooler 2, and therefore the effect on the temperature of the capacitor element 41 is negligible.

[0038] <DC Power Supply Connection Bus Bar 71> The capacitor 4 and the DC power supply 7 are connected via a DC power supply connection bus bar 71. The DC power supply connection bus bar 71 includes a DC power supply connection positive bus bar 71a and a DC power supply connection negative bus bar 71b. One end of the DC power supply connection positive bus bar 71a is electrically connected to the DC power supply 7, and the other end is electrically connected to the first connection terminal 45a of the positive bus bar 42a. One end of the DC power supply connection negative bus bar 71b is electrically connected to the DC power supply 7, and the other end is electrically connected to the second connection terminal 45b of the negative bus bar 42b. The DC power supply connection positive bus bar 71a and the DC power supply connection negative bus bar 71b are thermally connected to the cooler 2 via heat transfer members. In this embodiment, the heat transfer members are a base 74 and grease 75. The heat transfer members will be described in detail below. In this embodiment, the positive bus bar 71a for connecting to a DC power supply and the negative bus bar 71b for connecting to a DC power supply are the same in size, but the sizes of the positive bus bar 71a for connecting to a DC power supply and the negative bus bar 71b for connecting to a DC power supply are not limited to this.

[0039] With this configuration, heat generated in the DC power supply connection bus bar 71 can be dissipated to the cooler 2 while ensuring insulation between the DC power supply connection bus bar 71 and the cooler 2. Therefore, the temperature of the DC power supply connection bus bar 71 is lower than that of the other component connection terminals 45, and heat from the capacitor bus bar 42 and the capacitor elements 41 can be dissipated to the cooler 2 via the other component connection terminals 45. Since heat from the condenser bus bar 42 and the capacitor elements 41 is dissipated to the cooler 2, heat-induced deterioration of the capacitor elements 41 can be suppressed. Furthermore, because the cross-sectional area of ​​the first connection terminal 45a is larger than the cross-sectional area of ​​the second connection terminal 45b, heat from the positive bus bar 42a, which has a smaller amount of heat transfer to the cooler 2, can dissipate more heat to the cooler 2 via the DC power supply connection bus bar 71 than from the negative bus bar 42b.

[0040] The first connection terminal 45a and the second connection terminal 45b are connected to another component by screwing. In the present embodiment, the other component is a DC power supply connection bus bar 71. As shown in Fig. 2, the first connection terminal 45a and the DC power supply connection positive bus bar 71a are connected to each other by a screw 72. The screw 72 is omitted from Fig. 1.

[0041] This configuration allows the power conversion device 1 to be manufactured more inexpensively than when connections are made by welding. Furthermore, since the other component connection terminals 45 and the DC power supply connection bus bar 71 can be connected over a large area, it is possible to reduce the contact thermal resistance between the other component connection terminals 45 and the DC power supply connection bus bar 71. Because the contact thermal resistance between the other component connection terminals 45 and the DC power supply connection bus bar 71 is reduced, more heat can be dissipated from the condenser 4 to the cooler 2 via the DC power supply connection bus bar 71.

[0042] The connection between the first connection terminal 45a and the second connection terminal 45b and other components is not limited to the use of screws 72. The first connection terminal 45a and the second connection terminal 45b may be connected to the DC power supply bus bar 71, which is another component, by welding. As shown in FIG. 4 , the portion between the first connection terminal 45a and the DC power supply positive bus bar 71a is a welded portion 73 where the first connection terminal 45a and the DC power supply positive bus bar 71a are welded. The portion between the second connection terminal 45b and the DC power supply negative bus bar 71b is a welded portion 73 where the second connection terminal 45b and the DC power supply negative bus bar 71b are welded. This configuration reduces the contact thermal resistance between the first connection terminal 45a and the second connection terminal 45b and the DC power supply bus bar 71. This reduces the thermal contact resistance between the first connection terminal 45 a and the second connection terminal 45 b and the DC power supply bus bar 71, thereby improving the heat dissipation effect from the first connection terminal 45 a and the second connection terminal 45 b to the DC power supply bus bar 71. Furthermore, compared to connections using screws, the first connection terminal 45 a and the second connection terminal 45 b can be connected to the DC power supply bus bar 71 in a space-saving manner.

[0043] In this embodiment, the heat transfer member is an insulating material and grease 75 stacked one on top of the other. As shown in FIG. 2 , the insulating material is a resin base 74. The DC power supply connection bus bar 71 is fixed to the base 74 by, for example, adhesive or screws. The base 74 is thermally connected to the cooler 2 by, for example, screws via the grease 75. The DC power supply connection bus bar 71 and the base 74 may be fixed to the cooler 2 together by screws. By pressing the base 74 against the cooler 2 by screws or the like, the grease 75 can be made thinner. Because the grease 75 is made thinner, the contact thermal resistance between the base 74 and the cooler 2 can be made smaller than when a heat transfer member other than grease 75 is used. Because the contact thermal resistance between the base 74 and the cooler 2 is reduced, the heat dissipation from the DC power supply connection bus bar 71 to the cooler 2 can be improved.

[0044] When grease 75 is used in this manner, the grease 75 has good adhesion to the base 74 and the cooler 2, making it difficult for a gap to form between the base 74 and the cooler 2, thereby reducing the contact thermal resistance between the base 74 and the cooler 2. Furthermore, by reducing the thickness of the base 74, it is possible to further improve the heat dissipation from the DC power supply connection bus bar 71 to the cooler 2. The heat transfer member is not limited to the insulating material and grease 75, and may be another member such as a heat dissipation sheet.

[0045] The positive bus bar 42a is disposed so as to cover the upper surface of the capacitor element 41. With this configuration, heat transferred to the capacitor 4 from other components around the capacitor 4 via the air is dissipated from the first electrode main body portion 42c1 of the positive bus bar 42a via the first connection terminal 45a and the DC power supply connecting positive bus bar 71a to the cooler 2, and is not transferred to the capacitor element 41. In this embodiment, the substrate 5 is disposed in the normal direction of the capacitor 4. Heat-generating components are disposed on the surface normal to the substrate 5, but the heat from the heated components is shielded by the substrate 5.

[0046] <Y Capacitors 46, 47> In the present embodiment, a Y capacitor for noise removal is electrically connected to each of the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b. As shown in FIG. 1 , the Y capacitor 46 is connected to the first connection terminal 45a, and the Y capacitor 47 is connected to the second connection terminal 45b. The Y capacitors 46, 47 receive heat from the capacitor bus bar 42, just like the capacitor element 41. This heat may cause the Y capacitors 46, 47 to exceed their heat resistance temperature. Because the Y capacitors 46, 47 do not generate heat themselves, the temperatures of the Y capacitors 46, 47 are determined by the heat received from the outside.

[0047] In this embodiment, the cross-sectional area of ​​the first connection terminal 45a of the positive bus bar 42a, which transfers less heat to the cooler 2 and is therefore less easily cooled, is larger than the cross-sectional area of ​​the second connection terminal 45b of the negative bus bar 42b, and therefore the amount of heat generated by the first connection terminal 45a is small. Since the Y capacitor 46 is connected to the first connection terminal 45a, which has a larger cross-sectional area and generates less heat, the temperature of the Y capacitor 46 can be effectively reduced. Since the second connection terminal 45b of the negative bus bar 42b transfers a large amount of heat to the cooler 2, it is possible to suppress a rise in temperature of the Y capacitor 47 connected to the second connection terminal 45b.

[0048] In the present embodiment, the Y capacitors 46, 47 are housed in the case 44, and are connected to the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b inside the case 44. With this configuration, the Y capacitors 46, 47 and the capacitor element 41 are housed in the same case 44, which reduces dead space in the capacitor 4 and allows the capacitor 4 to be made smaller. Furthermore, because the capacitor 4 is made smaller, the components of the power conversion device 1 can be arranged in a more space-saving manner.

[0049] <Installation Example of Power Conversion Device 1> As shown in Fig. 5 , the power conversion device 1 is a device mounted on, for example, a vehicle 9. The vehicle 9 has a heat generation source 10. When the power conversion device 1 is mounted on the vehicle 9, the power conversion device 1 is thermally connected to the heat generation source 10, which is an engine, a transmission, or a motor. The cooler 2 is connected to the heat generation source 10 in the vehicle 9. In Fig. 5 , the cooler 2 is indicated by a dashed line. When the power conversion device 1 is mounted on a vehicle and used, the amount of heat received from an external heat source also increases, and the temperature of the power conversion device 1 is likely to rise. By using the power conversion device 1 described in the first embodiment, heat from the external heat source can be efficiently dissipated.

[0050] As described above, in the power conversion device 1 according to the first embodiment, when the thermal conduction from the first electrode to the cooler is greater than the thermal conduction from the second electrode to the cooler, the cross-sectional area of ​​the second connection terminal in the direction perpendicular to the current flow is larger than the cross-sectional area of ​​the first connection terminal in the direction perpendicular to the current flow, and when the thermal conduction from the second electrode to the cooler is greater than the thermal conduction from the first electrode to the cooler, the cross-sectional area of ​​the first connection terminal in the direction perpendicular to the current flow is larger than the cross-sectional area of ​​the second connection terminal in the direction perpendicular to the current flow. Therefore, without adding any new components, the amount of heat generated by the first connection terminal of the first electrode or the second connection terminal of the second electrode, which has low thermal conduction to the cooler and is therefore difficult to cool, is reduced, thereby reducing the amount of heat transferred to the electronic components. Because the amount of heat transferred to the electronic components is reduced, a power conversion device can be obtained that suppresses temperature increases in the electronic components while maintaining a small size.

[0051] In a case where the electronic component is a capacitor 4, the main body is one or more capacitor elements 41, the first electrode is a positive bus bar 42a, the second electrode is a negative bus bar 42b, and the capacitor 4 further includes a case 44 that houses the capacitor element 41, the positive bus bar 42a, and the negative bus bar 42b, the cross-sectional area of ​​the first connection terminal 45a of the positive bus bar 42a, which is difficult to cool and transfers less heat to the cooler 2, is larger than the cross-sectional area of ​​the second connection terminal 45b of the negative bus bar 42b. This reduces the amount of heat generated by the first connection terminal 45a, thereby reducing the amount of heat transferred to the capacitor element 41. This reduces the amount of heat transferred to the capacitor element 41, thereby suppressing a temperature rise in the capacitor 4. Furthermore, because the capacitor element 41, the positive bus bar 42a, and the negative bus bar 42b are housed in the case 44, the productivity of the power conversion device 1 can be improved.

[0052] When the DC power supply connecting positive bus bar 71a and the DC power supply connecting negative bus bar 71b are thermally connected to the cooler 2 via a heat transfer member, heat generated in the DC power supply connecting bus bar 71 can be dissipated to the cooler 2 while ensuring insulation between the DC power supply connecting bus bar 71 and the cooler 2. Therefore, the temperature of the DC power supply connecting bus bar 71 is lower than that of the other component connecting terminal 45, and therefore heat from the capacitor bus bar 42 and the capacitor element 41 can be dissipated to the cooler 2 via the other component connecting terminal 45. Because the heat from the capacitor bus bar 42 and the capacitor element 41 is dissipated to the cooler 2, heat-induced deterioration of the capacitor element 41 can be suppressed.

[0053] When a Y capacitor for noise removal is electrically connected to each of the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b, the Y capacitor 46 is connected to the first connection terminal 45a, which has a large cross-sectional area and generates a small amount of heat, thereby effectively lowering the temperature of the Y capacitor 46. The second connection terminal 45b of the negative bus bar 42b transfers a large amount of heat to the cooler 2, thereby suppressing a temperature rise in the Y capacitor 47 connected to the second connection terminal 45b.

[0054] When the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b have the same thickness but the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b have different widths perpendicular to the direction of current flow, the cross-sectional areas of the first connection terminal 45a and the second connection terminal 45b can be easily changed while maintaining the same thickness. Increasing the width of only the first connection terminal 45a and keeping the width of the second connection terminal 45b small allows the capacitor 4 to be more compact than when the widths of both the positive bus bar 42a and the negative bus bar 42b are increased.

[0055] When the heat transfer member is a base 74 and grease 75, which are insulating materials provided one on top of the other, the grease 75 can be made thinner by pressing the base 74 against the cooler 2 with screws or the like, and therefore the contact thermal resistance between the base 74 and the cooler 2 can be made smaller than when a heat transfer member other than grease 75 is used. Because the contact thermal resistance between the base 74 and the cooler 2 is reduced, the heat dissipation from the DC power supply connection bus bar 71 to the cooler 2 can be improved.

[0056] When the Y capacitors 46, 47 are housed in the case 44 and connected to the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b inside the case 44, the Y capacitors 46, 47 and the capacitor element 41 are housed in the same case 44, which reduces dead space in the capacitor 4 and enables the miniaturization of the capacitor 4. Furthermore, because the capacitor 4 is miniaturized, the components of the power conversion device 1 can be arranged in a space-saving manner.

[0057] When the first connection terminals 45 a and the second connection terminals 45 b are connected to the DC power supply connection bus bar 71, which is another component, by screwing, the power conversion device 1 can be manufactured more inexpensively than when the connection is made by welding. Furthermore, because the other component connection terminals 45 and the DC power supply connection bus bar 71 can be connected over a large area, the contact thermal resistance between the other component connection terminals 45 and the DC power supply connection bus bar 71 can be reduced. Because the contact thermal resistance between the other component connection terminals 45 and the DC power supply connection bus bar 71 is reduced, more heat can be dissipated from the condenser 4 to the cooler 2 via the DC power supply connection bus bar 71.

[0058] When the first connection terminals 45a and the second connection terminals 45b are connected to the DC power supply bus bar 71, which is another component, by welding, it is possible to reduce the thermal contact resistance between the first connection terminals 45a and the second connection terminals 45b and the DC power supply bus bar 71. Because the thermal contact resistance between the first connection terminals 45a and the second connection terminals 45b and the DC power supply bus bar 71 is reduced, it is possible to improve the heat dissipation effect from the first connection terminals 45a and the second connection terminals 45b to the DC power supply bus bar 71. Furthermore, compared to connections using screws, it is possible to connect the first connection terminals 45a and the second connection terminals 45b and the DC power supply bus bar 71 in a space-saving manner.

[0059] If the capacitor element 41 is a film capacitor, film capacitors generally have a higher withstand voltage than other types of capacitors, so by using a film capacitor for the capacitor element 41, the power conversion device 1 can be used for automotive applications that require high withstand voltage.

[0060] When the power conversion device 1 is mounted on a vehicle 9 and thermally connected to a heat generating source 10, such as an engine, a transmission, or a motor, the power conversion device 1 of the present disclosure can be used to efficiently dissipate heat from an external heat source.

[0061] Second Embodiment A power conversion device 1 according to a second embodiment will now be described. Fig. 6 is a plan view showing an outline of the power conversion device 1 according to the second embodiment, with the substrate 5 removed, Fig. 7 is a plan view showing an outline of the positive bus bar 42a of the power conversion device 1, Fig. 8 is a side view showing an outline of the positive bus bar 42a of the power conversion device 1, and Fig. 9 is a cross-sectional view of the power conversion device 1 taken along the CC cross section in Fig. 6. The power conversion device 1 according to the second embodiment has a different arrangement of the opening 49 of the case 44 from that of the first embodiment.

[0062] The electronic component included in the power conversion device 1 in this embodiment is a capacitor 4. As shown in Fig. 9 , the power conversion device 1 includes a semiconductor module 3 that is electrically connected to the capacitor 4 and arranged alongside the capacitor 4. A case 44 of the capacitor 4 has an opening on the side of the semiconductor module 3, and a first connection terminal 45a of the positive bus bar 42a and a second connection terminal 45b of the negative bus bar 42b protrude from an opening 49, which is the open portion of the case 44.

[0063] With this configuration, the first connection terminal 45a of the positive bus bar 42a and the second connection terminal 45b of the negative bus bar 42b do not protrude in the normal direction from the case 44, thereby reducing the size in the height direction of the power conversion device 1. In the present embodiment, as shown in Fig. 6 , the first connection terminal 45a and the second connection terminal 45b protrude from the opening 49 via the first electrode main body portion 42c1 and the second electrode main body portion 42c2, but this is not limited to this, and the first connection terminal 45a and the second connection terminal 45b may also protrude directly from the opening 49.

[0064] The positive power terminal 42a1 of the positive bus bar 42a protrudes from the opening 49 toward the semiconductor module 3 and is electrically connected to the positive bus bar 33a of the semiconductor module 3. Similarly, the negative power terminal 42b1 of the negative bus bar 42b protrudes from the opening 49 toward the semiconductor module 3 and is electrically connected to the negative bus bar 33b of the semiconductor module 3. This configuration allows the lengths of the positive power terminal 42a1 and the negative power terminal 42b1 to be shortened. Because the lengths of the positive power terminal 42a1 and the negative power terminal 42b1 are shortened, the capacitor 4 and the semiconductor module 3 can be connected with low wiring inductance, and excess loss in the capacitor bus bar 42 connecting the capacitor 4 and the semiconductor module 3 can be suppressed. Furthermore, because the positive power terminal 42a1 and the negative power terminal 42b1 do not protrude in the normal direction from the case 44, the height of the power conversion device 1 can be reduced.

[0065] The outer surface of the side wall 44b of the case 44 is thermally connected to the second surface 2c of the cooler 2. The thermal connection is not limited to a case where the side wall 44b and the second surface 2c are connected through direct contact, but the side wall 44b and the second surface 2c may be thermally connected via a heat transfer member such as grease or a heat dissipation sheet. By thermally connecting the case 44 to the cooler 2, the capacitor element 41 can dissipate heat from the side of the side wall 44b of the case 44, thereby improving the heat dissipation performance of the capacitor element 41.

[0066] In this embodiment, the Y capacitors 46, 47 are housed in a separate case 46a that is different from the case 44. In Fig. 6, only the outer shape of the case 46a is shown. This configuration makes it difficult for the Y capacitors 46, 47 to absorb the heat generated by the capacitor element 41. Furthermore, since the Y capacitors 46, 47 are smaller than the capacitor 4, there is greater freedom in the mounting position, and the Y capacitors 46, 47 can be placed in an optimal location taking into account factors such as heat, size, and noise removal performance.

[0067] In this embodiment, the positive bus bar 42a is an electrically conductive member formed by joining a first electrode main body 42c1 and a first connection terminal 45a, each having a different cross-sectional area, and the negative bus bar 42b is an electrically conductive member formed by joining a second electrode main body 42c2 and a second connection terminal 45b, each having a different cross-sectional area. As shown in FIG. 8 , the positive bus bar 42a has the first electrode main body 42c1 and the first connection terminal 45a, each having a different cross-sectional area, joined by a screw 72. The negative bus bar 42b has a similar configuration. FIG. 8 is a view of the positive bus bar 42a shown in FIG. 7 viewed from a second direction. The joining is not limited to screw fastening and may be welding. This configuration increases the flexibility of the capacitor bus bar 42's routing, thereby enabling the power converter 1 to be miniaturized. Note that the first electrode main body 42c1 and the positive power terminal 42a1, which are cut out from a single copper plate, are integrated together, but this is not a limitation. The first electrode main body portion 42c1 and the positive power terminal 42a1 may be formed from separate members.

[0068] In this embodiment, the heat transfer member is a heat dissipation sheet 76. As shown in FIG. 6 , the DC power supply bus bar 71 is thermally connected to the cooler 2 via the heat dissipation sheet 76. Because the heat dissipation sheet 76 has a stable shape, the heat dissipation sheet 76 can maintain the desired heat dissipation characteristics even when used for a long period of time and repeatedly exposed to high and low temperatures. Furthermore, by using the insulating heat dissipation sheet 76, it is not necessary to install a separate insulating member between the DC power supply bus bar 71 and the cooler 2. This reduces the distance between the DC power supply bus bar 71 and the cooler 2, thereby further improving the heat dissipation performance of the DC power supply bus bar 71. By improving the heat dissipation performance of the DC power supply bus bar 71, heat from the capacitor bus bar 42 and the capacitor element 41 is further dissipated to the cooler 2, thereby further suppressing heat-induced deterioration of the capacitor element 41.

[0069] Third Embodiment A power conversion device 1 according to a third embodiment will now be described. Fig. 10 is a plan view showing an outline of the power conversion device 1 according to the third embodiment, Fig. 11 is a cross-sectional view of the semiconductor module 3 of the power conversion device 1 taken along the D-D cross section of Fig. 10, and Fig. 12 is a cross-sectional view of the semiconductor module bus bar 33, which is a main part of the power conversion device 1, taken along the E-E cross section of Fig. 10. In the power conversion device 1 according to the third embodiment, the electronic component included in the power conversion device 1 is the semiconductor module 3.

[0070] The power conversion device 1 includes a capacitor 4 in addition to a semiconductor module 3. While the description of the configuration of the capacitor 4 is omitted in this embodiment, the capacitor 4 may have the configuration shown in embodiment 1 or 2. As shown in FIG. 10 , the semiconductor module 3 and the capacitor 4 are thermally connected to a cooler 2. As shown in FIG. 11 , the semiconductor module 3 includes a semiconductor element 31, a positive bus bar 33 a (not shown in FIG. 11 ), a negative bus bar 33 b, a heat spreader 32 for heat dissipation, an insulating member 36, and a sealing resin 35 that integrally seals these components. The semiconductor module 3 is thermally connected to the cooler 2 via the insulating member 36. A bonding material 34, such as solder or grease, is provided between the insulating member 36 and the cooler 2. While the present embodiment illustrates an example in which there is a single semiconductor element 31, the number of semiconductor elements 31 is not limited to one and may be multiple.

[0071] The semiconductor element 31 has electrodes on one surface and the other surface. If the semiconductor element 31 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), the electrodes are a drain and a source. If the semiconductor element 31 is an IGBT (Insulated Gate Bipolar Transistor), the electrodes are a collector and an emitter. An electrode 31a on one surface of the semiconductor element 31 is connected to the heat spreader 32 via a bonding material 34a such as solder. An electrode 31b on the other surface of the semiconductor element 31 is connected to a negative bus bar 33b via a bonding material 34a such as solder. As shown in FIG. 12 , the positive bus bar 33a is connected via the bonding material 34a to the same surface of the heat spreader 32 on which the semiconductor element 31 is provided. An insulating member 36 is arranged on the surface of the heat spreader 32 opposite to the surface on which the semiconductor elements 31 are provided. The positive bus bar 33 a and the negative bus bar 33 b extend parallel to the surface of the cooler 2 on which the semiconductor modules 3 are provided, and protrude from the sealing resin 35.

[0072] The main body of the electronic component is one or more semiconductor elements 31, the first electrode is negative bus bar 33b, and the second electrode is heat spreader 32 and positive bus bar 33a. The portion of negative bus bar 33b connected to semiconductor element 31 is a first electrode main body, and the portion of negative bus bar 33b that protrudes from sealing resin 35 and is connected to another component, capacitor 4, is a first connection terminal. Heat spreader 32 is a second electrode main body, and positive bus bar 33a is a second connection terminal. In this embodiment, as shown in FIG. 12 , the cross-sectional area of ​​negative bus bar 33b is larger than the cross-sectional area of ​​positive bus bar 33a.

[0073] Because the path to the cooler 2 passes through the semiconductor element 31, which is a heat source, the negative bus bar 33b transfers less heat to the cooler 2 than the positive bus bar 33a, which is directly connected to the heat spreader 32. When a large current flows through the semiconductor element 31, not only the semiconductor element 31 generates heat itself but also the heat received from the semiconductor module bus bar 33 increases, which may cause the temperature of the semiconductor element 31 to exceed an allowable value. Because the heat of the negative bus bar 33b is directly connected to the semiconductor element 31, it has a large effect on the temperature of the semiconductor element 31. Therefore, the temperature of the semiconductor element 31 can be lowered by increasing the cross-sectional area of ​​the negative bus bar 33b in a direction perpendicular to the current path 8, which is the direction in which the current flows, and reducing the amount of heat generated by the negative bus bar 33b.

[0074] Furthermore, when the temperatures of other components connected to the semiconductor module bus bar 33 are low, the heat of the semiconductor module 3 can be dissipated to the other components. In this embodiment, the first connection terminal and the second connection terminal of the semiconductor module 3 are connected to the capacitor bus bar (not shown) of the capacitor 4 by welding, so that part of the heat of the semiconductor element 31 is dissipated to the capacitor 4 side.

[0075] In the present embodiment, the capacitor 4 is electrically connected to the semiconductor module 3 via a first connection terminal and a second connection terminal provided on the semiconductor module 3. The first connection terminal is a portion of the negative bus bar 33b that protrudes from the sealing resin 35 and is connected to the capacitor 4, and the second connection terminal is the positive bus bar 33a. The cooler 2 has a forced cooling unit 21 provided with a flow path 22 through which a refrigerant flows, and the semiconductor module 3 is thermally connected to the forced cooling unit 21.

[0076] With this configuration, when the temperature of the capacitor 4 to which the semiconductor module 3 is connected is high, the heat of the capacitor bus bar of the capacitor 4 can be efficiently dissipated to the flow path 22 .

[0077] Fourth Embodiment A power conversion device 1 according to a fourth embodiment will now be described. Fig. 13 is a cross-sectional view showing an outline of the power conversion device 1 according to the fourth embodiment, in which the power conversion device 1 is cut at the same position as in Fig. 2, Fig. 14 is a side view showing an outline of the rapid discharge resistor 6 of the power conversion device 1, and Fig. 15 is a cross-sectional view of a main part of the rapid discharge resistor 6 cut at the F-F cross section position in Fig. 14. In the power conversion device 1 according to the fourth embodiment, the electronic component included in the power conversion device 1 is the rapid discharge resistor 6 that releases the charge stored in the capacitor 4.

[0078] The power conversion device 1 includes a semiconductor module 3 in addition to a capacitor 4 and a rapid discharge resistor 6. While the configurations of the semiconductor module 3 and the capacitor 4 are not described in this embodiment, the semiconductor module 3 and the capacitor 4 may have the configurations described in the first to third embodiments. The rapid discharge resistor 6 is provided to discharge the charge accumulated in the capacitor 4 when an abnormality is detected in the power conversion device 1. As shown in FIG. 14 , the rapid discharge resistor 6 includes a resistor 62 that discharges the charge of the capacitor 4, a lead wire 61 that electrically connects the resistor 62 and the capacitor 4, and a case 63 that houses the resistor 62. In this embodiment, a first lead wire 61 a and a second lead wire 61 b ​​are provided as the lead wire 61. The first lead wire 61 a is connected to the first connection terminal 45 a, and the second lead wire 61 b ​​is connected to the second connection terminal 45 b (not shown in FIG. 13 ). The case 63 is thermally connected to the cooler 2, as shown in FIG. 13 . In this embodiment, an example in which there is a single resistor 62 has been shown, but the number of resistors 62 is not limited to one, and there may be a plurality of resistors 62 .

[0079] 14, the resistor 62 has electrodes on one and the other surfaces. The electrode 62a on one surface of the resistor 62 is connected to a first lead wire 61a via a bonding material (not shown) such as solder. The electrode 62b on the other surface of the semiconductor element 31 is connected to a second lead wire 61b via a bonding material (not shown) such as solder. The first lead wire 61a and the second lead wire 61b protrude from the case 63 to the other side in the first direction.

[0080] The main body of the electronic component is one or more resistors 62, the first electrode is the second lead wire 61b, and the second electrode is the first lead wire 61a. The portion of the second lead wire 61b connected to the resistor 62 is a first electrode main body, and the portion of the second lead wire 61b protruding from the case 63 and connected to the other component, the capacitor 4, is a first connection terminal. The portion of the first lead wire 61a connected to the resistor 62 is a second electrode main body, and the portion of the first lead wire 61a protruding from the case 63 and connected to the other component, the capacitor 4, is a second connection terminal. In this embodiment, as shown in FIG. 15 , the cross-sectional area of ​​the second lead wire 61b is larger than the cross-sectional area of ​​the first lead wire 61a.

[0081] Because the capacitor 4 mounted in the on-vehicle power conversion device 1 has a large capacity, the rapid discharge resistor 6 generates a large amount of heat during discharge. The heat generated by the rapid discharge resistor 6 may exceed its own heat resistance temperature and may cause thermal damage to components disposed around the rapid discharge resistor 6. Therefore, by making the cross-sectional area of ​​the second lead wire 61b, which dissipates less heat to the cooler 2, larger than that of the first lead wire 61a, the heat from the rapid discharge resistor 6 can be dissipated to the outside via the lead wire. Furthermore, by increasing the cross-sectional area of ​​the second lead wire 61b, the heat from the rapid discharge resistor 6 can be further dissipated from the surface of the second lead wire 61b to the air, thereby lowering the temperature of the rapid discharge resistor 6. In this embodiment, the cooler 2 closer to the forced cooling section 21 having the flow path 22 is at a lower temperature, and the amount of heat transferred from the rapid discharge resistor 6 to the cooler 2 is greater. Therefore, by increasing the cross-sectional area of ​​the second lead wire 61b on the side farther from the forced cooling section 21, the heat from the rapid discharge resistor 6 is dissipated via the lead wire.

[0082] Fifth embodiment. A power conversion device 1 according to a fifth embodiment will be described. Fig. 16 is a cross-sectional view showing an outline of a substrate 5 of a power conversion device 1 according to the fifth embodiment, and Fig. 17 is a cross-sectional view of the substrate 5 of the power conversion device 1 taken along the G-G cross section in Fig. 16. In the power conversion device 1 according to the fifth embodiment, the electronic component provided in the power conversion device 1 is a heat-generating component 51 provided on the substrate 5. The first connection terminal and the second connection terminal are patterns 52 provided on the substrate 5.

[0083] The power conversion device 1 includes, for example, a semiconductor module 3, a capacitor 4, and a rapid discharge resistor 6 in addition to a substrate 5 on which a heat-generating component 51 is mounted. While the configurations of the semiconductor module 3, the capacitor 4, and the rapid discharge resistor 6 are not described in this embodiment, the configurations of the semiconductor module 3, the capacitor 4, and the rapid discharge resistor 6 may be the same as those described in the first to fourth embodiments. The substrate 5 is a control substrate on which electronic components used to control the power conversion device 1 are mounted. As shown in FIG. 16 , the substrate 5 includes a main body portion on which an insulating layer 53 and a pattern 52 serving as a current path and a heat dissipation path are laminated, and at least one heat-generating component 51 is disposed on one side of the substrate 5. As shown in FIG. 17 , the pattern 52 includes a first pattern 52a and a second pattern 52b having different cross-sectional areas. In this embodiment, the cross-sectional area of ​​the first pattern 52a is larger than that of the second pattern 52b. The pattern 52 is thermally connected to the cooler 2 via a cooler connection portion 55. In this embodiment, the substrate 5 has two heat-generating components 51, but the number of heat-generating components 51 is not limited to this.

[0084] The heat-generating component 51 is, for example, a microcomputer for controlling the power conversion device 1, a semiconductor module, or a resistor. In this embodiment, a case where the heat-generating component 51 is a semiconductor module will be described, but the heat-generating component 51 is not limited to a semiconductor module. The semiconductor module is composed of a semiconductor element 56, a first lead wire 52a1, a second lead wire 52b1, a heat spreader 57 for heat dissipation, an insulating member 58, and a sealing resin 59 that integrally seals these components. The semiconductor module is thermally connected to the first pattern 52a via the insulating member 58. Solder 54, which serves as a bonding material, is provided between the insulating member 36 and the first pattern 52a.

[0085] The semiconductor element 56 has electrodes on one surface and the other surface. If the semiconductor element 56 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), the electrodes are a drain and a source. If the semiconductor element 31 is an IGBT (Insulated Gate Bipolar Transistor), the electrodes are a collector and an emitter. The electrode 56b on the other surface of the semiconductor element 56 is connected to the heat spreader 57 via a bonding material (not shown) such as solder. The electrode 56a on one surface of the semiconductor element 56 is connected to the first lead wire 52a1 via a bonding material (not shown) such as solder. The second lead wire 52b1 is connected to the same surface of the heat spreader 57 on which the semiconductor element 56 is provided, via a bonding material (not shown). An insulating member 58 is disposed on the surface of the heat spreader 57 opposite to the surface on which the semiconductor element 56 is disposed. The first lead wire 52a1 and the second lead wire 52b1 extend parallel to the surface of the cooler 2 on which the substrate 5 is disposed, and protrude from the sealing resin 59.

[0086] The main body of the electronic component is a semiconductor element 56, the first electrode is a first lead wire 52a1 and a first pattern 52a, and the second electrode is a heat spreader 57, a second lead wire 52b1, and a second pattern 52b. The portion of the first lead wire 52a1 connected to the semiconductor element 56 is a first electrode main body, and the first pattern 52a connected to the first lead wire 52a1 is a first connection terminal. The heat spreader 57 is a second electrode main body, and the second pattern 52b is a second connection terminal. The first pattern 52a and the second pattern 52b are connected to, for example, a capacitor, which is another component. The second lead wire 52b1 and the first pattern 52a are not electrically connected.

[0087] The heat-generating component 51 is thermally connected to a pattern 52 on the substrate 5 via solder 54 or the like, and the pattern 52 is thermally connected to the cooler 2. Because the distance from the cooler 2 is greater than that of the second pattern 52b, the cross-sectional area of ​​the first pattern 52a, which has a smaller amount of heat dissipation to the cooler 2, can be made larger than that of the second pattern 52b, so that more heat from the heat-generating component 51 can be dissipated to the cooler 2. Furthermore, because the heat from the heat-generating component 51 can be dissipated over a wider area via the first pattern 52a, the amount of heat dissipated from the substrate 5 to the air also increases, and the temperatures of the heat-generating component 51 and the substrate 5 itself can be lowered.

[0088] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0089] REFERENCE SIGNS LIST 1 Power conversion device, 2 Cooler, 2a Step, 2b First surface, 2c Second surface, 21 Forced cooling section, 22 Flow path, 23 Flow path forming section, 24a, 24b Refrigerant inlet / outlet, 3 Semiconductor module, 3a Module main body, 31 Semiconductor element, 31a, 31b Electrode, 32 Heat spreader, 33 Semiconductor module bus bar, 33a Positive bus bar, 33b Negative bus bar, 34, 34a Bonding material, 35 Sealing resin, 36 Insulating member, 38 Output terminal, 4 Capacitor, 41 Capacitor element, 42 Capacitor bus bar, 42a Positive bus bar, 42a1 Positive power terminal, 42a2 Board connection terminal, 42b Negative bus bar, 42b1 Negative power terminal, 42c1 First electrode main body, 42c2 Second electrode main body, 43 Sealing resin, 44 Case, 44a bottom wall, 44b side wall, 45 terminal for connecting other components, 45a first connecting terminal, 45b second connecting terminal, 46, 47 Y capacitor, 46a case, 48 electrode, 48a positive electrode, 48b negative electrode, 49 opening, 5 substrate, 51 heat-generating component, 52 pattern, 52a first pattern, 52a1 first lead wire, 52b second pattern, 52b1 second lead wire, 53 insulating layer, 54 solder, 55 cooler connection portion, 56 semiconductor element, 56a, 56b electrodes, 57 heat spreader, 58 insulating member, 59 sealing resin, 6 rapid discharge resistor, 61 lead wire, 61a first lead wire, 61b second lead wire, 62 resistor, 62a, 62b electrodes, 63 case, 7 DC power supply, 71 DC power supply connection bus bar, 71a DC power supply connection positive bus bar, 71b DC power supply connection negative bus bar, 72 screw, 73 welded portion, 74 base, 75 grease, 76 heat dissipation sheet, 8 current path, 9 vehicle, 10 heat generation source

Claims

1. An electronic component having a main body which is a heating element, a first electrode electrically connected to one side of the main body, and a second electrode electrically connected to the other side opposite to the one side of the main body, the first electrode being stacked in this order in the main body and a cooler which cools the electronic component, wherein the first electrode has a first electrode main body connected to the main body, and a first connection terminal connected to the first electrode main body and connected to another component on the side opposite to the first electrode main body, the second electrode has a second electrode main body connected to the main body, and a second connection terminal connected to the second electrode main body and connected to another component on the side opposite to the second electrode main body, when the thermal conduction from the first electrode to the cooler is greater than the thermal conduction from the second electrode to the cooler, a cross-sectional area of ​​the second connection terminal in a direction perpendicular to the direction of current flow is greater than a cross-sectional area of ​​the first connection terminal in a direction perpendicular to the direction of current flow, A power conversion device in which, when thermal conduction from the second electrode to the cooler is greater than thermal conduction from the first electrode to the cooler, a cross-sectional area of ​​the first connection terminal in a direction perpendicular to the direction of current flow is greater than a cross-sectional area of ​​the second connection terminal in a direction perpendicular to the direction of current flow.

2. The power conversion device according to claim 1, wherein the electronic component is a capacitor, the main body is one or more capacitor elements, the first electrode is a positive bus bar, and the second electrode is a negative bus bar, and the capacitor further has a case that houses the capacitor element, the positive bus bar, and the negative bus bar.

3. The power conversion device according to claim 2, further comprising: a positive bus bar for connecting a DC power source, one end of which is electrically connected to the DC power source and the other end of which is electrically connected to the first connection terminal of the positive bus bar; and a negative bus bar for connecting a DC power source, one end of which is electrically connected to the DC power source and the other end of which is electrically connected to the second connection terminal of the negative bus bar, wherein the positive bus bar for connecting a DC power source and the negative bus bar for connecting a DC power source are thermally connected to the cooler via a heat transfer member.

4. A power conversion device as claimed in claim 2 or 3, further comprising a semiconductor module electrically connected to the capacitor and arranged alongside the capacitor, wherein the case of the capacitor has an opening on the side of the semiconductor module, and the first connection terminal of the positive bus bar and the second connection terminal of the negative bus bar protrude from the open portion of the case.

5. A power conversion device according to any one of claims 2 to 4, wherein a Y capacitor for removing noise is electrically connected to each of the first connection terminal of the positive bus bar and the second connection terminal of the negative bus bar.

6. A power conversion device according to any one of claims 2 to 5, wherein the first connection terminal of the positive bus bar and the second connection terminal of the negative bus bar have an equal thickness, and the first connection terminal of the positive bus bar and the second connection terminal of the negative bus bar have different widths in a direction perpendicular to a direction in which current flows.

7. A power conversion device as claimed in any one of claims 2 to 6, wherein the positive bus bar is an electrically conductive member joining the first electrode main body and the first connection terminal, which have different cross-sectional areas, and the negative bus bar is an electrically conductive member joining the second electrode main body and the second connection terminal, which have different cross-sectional areas.

8. The power conversion device according to claim 3, wherein the heat transfer member is an insulating material and grease provided in layers.

9. The power conversion device according to claim 3, wherein the heat transfer member is a heat dissipation sheet.

10. A power conversion device as described in claim 5, wherein the Y capacitor is housed in the case, and the Y capacitor is connected inside the case to each of the first connection terminal of the positive bus bar and the second connection terminal of the negative bus bar.

11. The power conversion device according to claim 5, wherein the Y capacitor is housed in a separate case different from the case.

12. The power conversion device according to claim 1, wherein the electronic component is a semiconductor module, the main body is one or more semiconductor elements, and the semiconductor module is thermally connected to the cooler via an insulating member.

13. The power conversion device according to claim 1, further comprising a capacitor, the electronic component being a rapid discharge resistor that discharges electric charge stored in the capacitor, and the main body being one or more resistors.

14. A power conversion device as described in claim 1, further comprising a substrate, the electronic component being a heat-generating component carried by the substrate, and the first connection terminal and the second connection terminal being patterns provided on the substrate.

15. A power conversion device as described in claim 12, further comprising a capacitor, the capacitor being electrically connected to the semiconductor module via the first connection terminal and the second connection terminal of the semiconductor module, the cooler having a forced cooling section provided with a flow path through which a refrigerant flows, and the semiconductor module being thermally connected to the forced cooling section.

16. A power conversion device according to any one of claims 1 to 15, wherein the first connection terminal, the second connection terminal and the other component are connected by screwing.

17. A power conversion device according to any one of claims 1 to 15, wherein the first connection terminal and the second connection terminal are connected to the other component by welding.

18. A power conversion device according to any one of claims 2 to 11, wherein the capacitor element is a film capacitor.

19. The power conversion device according to any one of claims 1 to 18, which is mounted on a vehicle and thermally connected to a heat generating source, such as an engine, a transmission, or a motor.

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