Electric power conversion device

Abstract

An electric power conversion device (1) comprises: a capacitor (4) that has a plurality of capacitor bus bars (42); a semiconductor module (3) that has a plurality of module bus bars (32); and a cooler (2), wherein: each of the plurality of module bus bars (32) has a different length from a bus bar connection portion on one side that is connected to a capacitor bus bar (42) to an in-module connection portion on the other side that is electrically connected to a portion inside the semiconductor module (3); in each of the plurality of capacitor bus bars (42), the thermal resistance from a capacitor connection portion that is electrically connected to a capacitor element (41) to a portion of the cooler (2) to which the capacitor (4) is thermally connected is different, and the longest module bus bar, which is the module bus bar (32) that has the longest length, and the capacitor bus bar (42) that has the smallest thermal resistance are electrically connected.

Description

Power conversion device

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

[0002] Equipment such as electric vehicles, railway vehicles, and industrial robots that use a motor as a drive source are equipped with a power conversion device such as an inverter for driving the motor and a converter for boosting and bucking the power supply voltage of a battery. Electric vehicles and railway vehicles are required to have a limited space for the loading space and passenger living space inside the vehicle, and industrial robots are required to be installed in a limited space in the factory. Therefore, the power conversion device is required to be installed in a limited space. Therefore, the power conversion device is required to be a small component. In addition, since the power conversion device is connected to a heat source such as a battery, a transmission, or a motor, the power conversion device is required to have high durability against heat.

[0003] Power conversion devices such as inverters and converters often include a capacitor having a capacitor element for smoothing a direct current supplied from an external direct current power source. The capacitor is one of the electronic components included in the power conversion device. Since a ripple current flows through the capacitor, the capacitor consumes power and generates heat. In addition, the capacitor is connected to other components via a bus bar. Therefore, heat is transferred from other components to the capacitor via the bus bar, and the capacitor may become hot due to the transferred heat. The temperature rise of the capacitor reduces the life of the capacitor element, so measures against the temperature rise of the capacitor have become an issue.

[0004] As a measure against the temperature rise of the capacitor, a configuration has been disclosed in which measures are taken for heat transfer from the bus bar to the capacitor while reducing the inductance of the bus bar (see, for example, Patent Document 1). In the configuration disclosed in Patent Document 1, by arranging the bus bar at the opposing portion facing the semiconductor module on the side surface of the capacitor element, the path inductance of the bus bar is reduced while reducing the heat transfer from the bus bar to the capacitor.

[0005] Japanese Patent No. 7391134

[0006] In Patent Document 1, a busbar is placed on the side of the capacitor element facing the semiconductor module, which suppresses heat transfer from the capacitor busbar to the capacitor. However, because the wiring within the semiconductor module is not indicated, a busbar that becomes hotter within the semiconductor module may be connected to a busbar that becomes hotter within the capacitor. In such a case, there is a problem that the heat generated by these connected busbars may cause the temperature of both the semiconductor module and the capacitor to rise.

[0007] Therefore, the purpose of this disclosure is to obtain a power conversion device that suppresses the temperature rise of the capacitor while maintaining miniaturization.

[0008] The power conversion device of the present disclosure comprises a capacitor having one or more capacitor elements and a plurality of capacitor busbars electrically connected to the capacitor elements, one or more semiconductor modules having a plurality of module busbars on one side electrically connected to each of the plurality of capacitor busbars, and a cooler for cooling the capacitor and the semiconductor modules, wherein each of the plurality of module busbars has a different length from the busbar connection portion on one side connected to the capacitor busbar to the internal module connection portion on the other side electrically connected to the internal part of the semiconductor module, each of the plurality of capacitor busbars has a different thermal resistance from the capacitor connection portion electrically connected to the capacitor element to the part of the cooler to which the capacitor is thermally connected, and the longest module busbar, which is the module busbar with the longest length, and the capacitor busbar with the smallest thermal resistance are electrically connected.

[0009] The power conversion device of this disclosure comprises a capacitor having one or more capacitor elements and a plurality of capacitor busbars electrically connected to the capacitor elements, one or more semiconductor modules having a plurality of module busbars on one side electrically connected to each of the plurality of capacitor busbars, and a cooler for cooling the capacitor and semiconductor modules. Each of the plurality of module busbars has a different length from the busbar connection portion on one side connected to the capacitor busbar to the module internal connection portion on the other side electrically connected to the internal part of the semiconductor module, and each of the plurality of capacitor busbars has a different thermal resistance from the capacitor connection portion electrically connected to the capacitor element to the part of the cooler to which the capacitor is thermally connected. Since the longest module busbar and the capacitor busbar with the smallest thermal resistance are electrically connected, the heat moving from the longest module busbar to the capacitor can be dissipated to the cooler, thus reducing the effect of heat moving from the semiconductor module to the capacitor elements. Because the effect of heat from the semiconductor module to the capacitor elements is small, the temperature rise of the capacitor can be suppressed. Furthermore, since the module busbar and the capacitor busbar are directly connected, no additional components are required to connect the module busbar and the capacitor busbar, thus maintaining the miniaturization of the power conversion device.

[0010] This is a plan view showing a schematic of the power converter according to Embodiment 1. This is a plan view showing the main parts of the capacitor and semiconductor module of the power converter according to Embodiment 1. This is a cross-sectional view of the power converter cut at the A-A cross-sectional position in Figure 1. This is a plan view showing the main parts of the capacitor and semiconductor module of the power converter according to Embodiment 2. This is a cross-sectional view of the power converter according to Embodiment 2. This is a cross-sectional view of the power converter according to Embodiment 3. This is a cross-sectional view of the power converter according to Embodiment 4.

[0011] The power conversion device according to the embodiment of this disclosure will be described below with reference to the figures. In each figure, the same or equivalent components and parts will be denoted by the same reference numerals.

[0012] Embodiment 1. Figure 1 is a schematic plan view of the power converter 1 according to Embodiment 1, with the control board 5 removed. Figure 2 is a plan view showing the main parts of the capacitor 4 and semiconductor module 3 of the power converter 1, showing the capacitor 4 and one semiconductor module 3. Figure 3 is a cross-sectional view of the power converter 1 cut at the A-A cross-sectional position in Figure 1. The power converter 1 is, for example, a device that converts the input current from DC to AC, AC to DC, or input voltage to a different voltage. In this embodiment, the power converter 1 is described as an inverter, but the power converter 1 is not limited to an inverter.

[0013] <Power Conversion Device 1> As shown in Figure 1, the power conversion device 1 comprises a capacitor 4, one or more semiconductor modules 3, a cooler 2 for cooling the capacitor 4 and semiconductor modules 3, and a control board 5 (not shown in Figure 1). The capacitor 4 has one or more capacitor elements 41 and a plurality of capacitor busbars 42 electrically connected to the capacitor elements 41. The semiconductor module 3 has a plurality of module busbars 32 on one side, each electrically connected to the plurality of capacitor busbars 42. Here, we define the directions. The direction parallel to the surface of the cooler 2 (cooling surface 25a in Figure 1) where the semiconductor modules 3 and capacitor 4 are arranged is defined as the X direction, the direction parallel to the cooling surface 25a and perpendicular to the X direction is defined as the Y direction, and the direction perpendicular to the X and Y directions is defined as the Z direction.

[0014] The power converter 1 is a device that receives DC power from the power supply side terminal (not shown) of a capacitor 4 connected to a DC power supply, smooths the DC power in the capacitor 4, and converts the resulting DC power in a semiconductor module 3 to output it to a load. The DC power supply is, for example, a secondary battery such as a lithium-ion battery. The load is, for example, a rotating electric machine. In this embodiment, the power converter 1 outputs three-phase AC. Therefore, the power converter 1 is equipped with three semiconductor modules 3, and each semiconductor module is composed of three semiconductor modules 3 corresponding to each phase. The number of semiconductor modules 3 is not limited to three; a single semiconductor module may be configured to output three-phase AC. Furthermore, the configuration of the power converter 1 is not limited to this; it may also be a device that converts the input current from AC to DC.

[0015] <Cooler 2> The configuration of each part of the power converter 1 will be explained in order. First, the cooler 2 will be explained. The cooler 2 is made of a metal such as aluminum. The method of manufacturing the cooler 2 is, for example, die casting. The material of the cooler 2 is not limited to aluminum, but may be an aluminum alloy, a magnesium alloy, copper, or a copper alloy. The cooler 2 is formed in a bottomed cylindrical shape as shown in Figure 3. In this embodiment, as shown in Figure 1, the bottom wall 25 of the cooler 2 is formed in a rectangular shape, so the cooler 2 is formed in a bottomed box shape. In this embodiment, the semiconductor module 3 and the capacitor 4 are mounted on the bottom wall 25 of the cooler 2.

[0016] As shown in Figure 3, the semiconductor module 3 is thermally connected to the surface of the cooler 2, and the cooler 2 has a flow path 21 that cools the semiconductor module 3 through the portion with the aforementioned surface. In this embodiment, the surface of the cooler 2 is the cooling surface 25a of the bottom wall 25. By providing the flow path 21, the semiconductor module 3 can be efficiently forced-cooled. A refrigerant flows through the flow path 21 to forcibly cool the semiconductor module 3. The refrigerant is, for example, a liquid such as water or ethylene glycol solution, or a gas such as air.

[0017] The forced cooling section 22 is composed of a flow path 21 and a flow path forming section 23 surrounding the flow path 21. The flow path forming section 23 is made of a metal such as aluminum, similar to the main body of the cooler 2. The material of the flow path forming section 23 is not limited to aluminum; it may also be made of a resin material with excellent thermal conductivity. Multiple cooling fins may be provided on the side of the bottom wall 25 opposite to the cooling surface 25a, in an area that overlaps with the semiconductor module 3 when viewed perpendicular to the cooling surface 25a.

[0018] As shown in Figure 1, the flow path forming section 23 has a refrigerant inlet / outlet 24. The refrigerant inlet / outlet 24 is an inlet / outlet for the refrigerant to flow into the flow path 21 or out of the flow path 21. The refrigerant inlet / outlet 24 has a portion that protrudes from the outer wall surface of the cooler 2. The refrigerant flows, for example, in the order of flow path inlet 24a, flow path 21, and flow path outlet 24b. In this embodiment, the flow path inlet 24a is located on the side of the condenser 4 that is perpendicular to the cooling surface 25a, rather than on the flow path outlet 24b. With this configuration, low-temperature refrigerant before it cools the semiconductor module 3 flows through the flow path 21 on the side of the flow path inlet 24a, so that the portion of the cooling surface 25a where the condenser 4 is located can also be efficiently cooled. Because the cooling surface 25a where the semiconductor module 3 is located is cooled by the refrigerant, the cooling surface 25a where the condenser 4 is located can also be cooled by heat conduction.

[0019] As shown in Figure 3, the semiconductor module 3 and the capacitor 4 are arranged on the same surface of the cooler 2. In this embodiment, the surface of the cooler 2 is the cooling surface 25a. This configuration minimizes the distance from the forced cooling unit 22 to the portion of the cooling surface 25a where the capacitor 4 is located, improving the cooling efficiency of the portion of the cooling surface 25a where the capacitor 4 is located, thus enabling efficient cooling of the capacitor 4. If the cooling surface 25a where the capacitor 4 is located and the cooling surface 25a where the semiconductor module 3 is located are at different heights, a dead space will be created below the higher surface. However, by arranging the capacitor 4 and the semiconductor module 3 on the same surface as in this embodiment, this dead space can be eliminated. Furthermore, since the height of the semiconductor module 3 is generally lower than the height of the capacitor 4, large components such as control boards can be placed in the height direction of the semiconductor module 3. Therefore, the power conversion device 1 can be miniaturized.

[0020] Furthermore, the power converter 1 may also be equipped with a cover that covers the open portion of the cooler 2. By providing a cover, the components mounted on the power converter 1 can be protected from foreign objects that may enter the power converter 1. If the cover is made of metal, the mounted components can be protected from electromagnetic noise.

[0021] <Semiconductor Module 3> Next, the semiconductor module 3 will be described. As shown in Figure 1, the semiconductor module 3 has one or more semiconductor chips 34, a module busbar 32, an AC current output busbar 33 for outputting AC current, and a plurality of control terminals (not shown). In this embodiment, the semiconductor module 3 has two semiconductor chips 34, which are shown by dashed lines. The number of semiconductor chips 34 is not limited to two; there may be one or more. In this embodiment, the semiconductor module 3 has two module busbars 32, an upper arm busbar 32a and a lower arm busbar 32b. The module busbars 32, the AC current output busbar 33, and the plurality of control terminals are provided protruding outward from the main body portion of the semiconductor module 3 that houses the semiconductor chips 34. The main body portion of the semiconductor module 3 is a sealing resin that surrounds the semiconductor chips 34.

[0022] The upper arm busbar 32a, the lower arm busbar 32b, the AC current output busbar 33, and the multiple control terminals are made of, for example, copper, which has low electrical resistivity and excellent conductivity. The upper arm busbar 32a is electrically connected to the positive busbar 42a, which is a capacitor busbar 42, and the lower arm busbar 32b is connected to the negative busbar 42b, which is a capacitor busbar 42.

[0023] In this embodiment, as shown in Figure 2, the semiconductor module 3 has an upper arm portion 3a that constitutes an upper arm and a lower arm portion 3b that constitutes a lower arm. The semiconductor module 3 and the capacitor 4 are arranged side by side on the cooling surface 25a of the cooler 2, and the upper arm portion 3a is positioned more adjacent to the capacitor 4 than the lower arm portion 3b when viewed perpendicular to the cooling surface 25a. In this embodiment, the semiconductor chip 34 of the upper arm portion 3a is electrically connected to the upper arm spreader 36, and the semiconductor chip 34 of the lower arm portion 3b is electrically connected to the lower arm spreader 35. The connection between the semiconductor chip 34 and each arm spreader is, for example, solder. Each arm spreader is made from, for example, a conductive metal such as copper. There may be multiple semiconductor chips 34 provided on each arm portion. The upper arm busbar 32a is electrically connected to the upper arm spreader 36 via a conductive bonding material such as solder, and the lower arm busbar 32b is electrically connected to the semiconductor chip 34 of the lower arm section 3b via a conductive bonding material such as solder. The AC current output busbar 33 is electrically connected to the semiconductor chip 34 of the upper arm section 3a and the lower arm spreader 35.

[0024] The AC current output busbar 33 is a busbar for outputting power converted to AC current by the semiconductor chip 34. The AC current output busbar 33 is located on the side of the semiconductor module 3 opposite to the capacitor 4, with the semiconductor chip 34 sandwiched between it and the capacitor 4. With this configuration, the AC current output busbar 33 does not protrude in the Y direction, so the size of the semiconductor module 3 in the Y direction can be reduced. Because the size of the semiconductor module 3 in the Y direction is reduced, the size of the power conversion device 1 in the Y direction can be miniaturized.

[0025] In this embodiment, as shown in Figure 1, a plurality of semiconductor modules 3 are provided, and the semiconductor modules 3 and capacitors 4 are arranged side by side on the cooling surface 25a of the cooler 2, and the plurality of semiconductor modules 3 are arranged in the Y direction. With this configuration, the semiconductor modules 3 can be arranged in parallel in the Y direction, so the power conversion device 1 can be made smaller.

[0026] The semiconductor chip 34 may be a power control semiconductor element such as a MOSFET (Metal Oxide Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or a freewheeling diode. However, the semiconductor chip 34 is not limited to these and may be other semiconductor elements such as bipolar transistors. Alternatively, an RC-IGBT (Reverse Conducting IGBT), which integrates a switching element and a freewheeling diode, may also be used.

[0027] The semiconductor chip 34 is formed on a semiconductor substrate made of materials such as silicon, silicon carbide, or gallium nitride, and the semiconductor chip 34 can use a wide-bandgap semiconductor element with a bandgap wider than that of silicon. When a MOSFET made of silicon carbide, which is a wide-bandgap semiconductor element, is used, the time change amount di / dt of the current generated during switching can be made larger than that of a MOSFET made of silicon. In addition, wide-bandgap semiconductor elements have low on-resistance, low loss, and low heat generation, so the chip area can be reduced. Since the chip area is reduced, the semiconductor module 3 can be miniaturized.

[0028] As shown in Figure 3, the portions of the upper arm spreader 36 and the lower arm spreader 35 opposite to the side on which the semiconductor chip 34 is attached are thermally connected to the insulating material 38. The portion of the insulating material 38 opposite to the portion thermally connected to the upper arm spreader 36 and the lower arm spreader 35 is thermally connected to the copper plate 39. The portion of the copper plate 39 opposite to the portion thermally connected to the insulating material 38 is exposed from the semiconductor module 3. The portion of the copper plate 39 exposed from the semiconductor module 3 is thermally connected to the cooling surface 25a via a bonding material 31 such as solder. In this embodiment, the bonding material 31 is solder, but the bonding material 31 may also be grease. Also, in this embodiment, a copper plate 39 is provided, but this portion is not limited to copper and may be made of other materials with excellent thermal conductivity such as aluminum. The copper plate 39 is a component for improving the bonding between the solder and the semiconductor module 3.

[0029] <Capacitor 4> Next, the capacitor 4 will be described. As shown in Figure 1, the capacitor 4 has one or more capacitor elements 41 and a plurality of capacitor busbars 42 electrically connected to the capacitor electrodes 43 (not shown in Figure 1) of the capacitor elements 41. In Figure 1, the positive electrode busbar 42a is also shown with a solid line on the inside of the capacitor case 45. The capacitor element 41 smooths the DC power. The capacitor element 41 is, for example, a film capacitor having a laminated structure in which metal foil and resin film, which serve as internal electrodes, are wound into a roll. As shown in Figure 3, the capacitor element 41 has capacitor electrodes 43 on the positive electrode side, which is one end of the capacitor, and on the negative electrode side, which is the other end of the capacitor. In this embodiment, the plurality of capacitor busbars 42 are positive electrode busbars 42a and negative electrode busbars 42b. The positive electrode busbars 42a and negative electrode busbars 42b are, for example, made from copper sheet metal, which has low electrical resistivity and excellent conductivity, by punching and bending. The positive busbar 42a is electrically connected to the positive electrode 43a, which is the positive side capacitor electrode 43, and the negative busbar 42b is electrically connected to the negative electrode 43b, which is the negative side capacitor electrode 43. The capacitor electrode 43 and the capacitor busbar 42 are connected via a conductive bonding material such as solder.

[0030] In this embodiment, the positional relationship between the capacitor element 41 and the capacitor electrode 43 is such that, when viewed in the Z direction, they are stacked as follows: positive electrode 43a, capacitor element 41, and negative electrode 43b. The electrode with the shorter distance in the Z direction to the cooler 2 is the negative electrode 43b, and the electrode with the longer distance in the Z direction to the cooler 2 is the positive electrode 43a.

[0031] The capacitor element 41 is housed in a capacitor case 45. The inside of the capacitor case 45 is filled with sealing resin 44, sealing the capacitor element 41. The sealing resin 44 is an insulating material made of epoxy resin or the like. The capacitor case 45 is made, for example, from aluminum die-casting or a resin material with high heat resistance such as PPS.

[0032] The side of the capacitor busbar 42 opposite to the side electrically connected to the capacitor electrode 43 protrudes from the sealing resin 44. In this embodiment, since the opening 45a of the capacitor case 45 is located on the side of the semiconductor module 3, the capacitor busbar 42 protrudes from the opening 45a of the capacitor case 45 toward the semiconductor module 3. The direction in which the opening 45a of the capacitor case 45 is provided is not limited to this; for example, it may be in the Z direction. When the opening 45a of the capacitor case 45 is provided on the side of the semiconductor module 3, the lengths of the capacitor busbar 42 and module busbar 32 can be shortened. As the lengths of the capacitor busbar 42 and module busbar 32 are shortened, the cost of the capacitor busbar 42 and module busbar 32 can be reduced.

[0033] In this embodiment, as shown in Figure 1, an example is shown in which three capacitor elements 41 are provided, but the number of capacitor elements 41 is not limited to this. The number of capacitor elements 41 may be one or more. Also, in this embodiment, one capacitor busbar 42 is connected to the capacitor electrodes 43 of the three capacitor elements 41, but this is not limited to this, and a capacitor busbar 42 may be connected individually to each of the capacitor electrodes 43 of the three capacitor elements 41.

[0034] The capacitor 4 is thermally connected to the cooling surface 25a of the cooler 2 via a heat dissipation member. In this embodiment, as shown in Figure 3, the capacitor case 45 is thermally connected to the cooling surface 25a. In this embodiment, the heat dissipation member is grease 61. This configuration reduces the thermal resistance between the capacitor 4 and the cooler 2, allowing the heat generated in the capacitor element 41 and the heat transferred to the capacitor element 41 via the capacitor busbar 42 to be dissipated to the cooler 2 more efficiently. Furthermore, when the heat dissipation member is grease 61, the thickness of the grease 61 can be reduced compared to other heat dissipation members, thus reducing the distance between the capacitor case 45 and the cooling surface 25a. As the distance between the capacitor case 45 and the cooling surface 25a is reduced, the thermal resistance between the capacitor 4 and the cooler 2 can be further reduced.

[0035] <Control Board 5> Next, the control board 5 will be described. The power converter 1 includes a control board 5 on which a control circuit for controlling the semiconductor module 3 is mounted. The control board 5 is, for example, a printed circuit board made of a multilayer board. The control board 5 and the semiconductor module 3 are connected by a plurality of control terminals (not shown) on the semiconductor module 3. The control board 5 is provided on the open side of the cooler 2 and is fixed to the cooler 2 by, for example, screws (not shown). It is preferable that the control board 5 is fixed in multiple places. By fixing the control board 5 in multiple places, the vibration resistance and heat dissipation of the control board 5 can be improved.

[0036] In this embodiment, the control board 5 is positioned so that at least a portion of it overlaps with the semiconductor module 3 when viewed perpendicular to the cooling surface 25a. This configuration allows for the placement of a large control board 5 without increasing the size of the cooler 2, thus enabling miniaturization of the power conversion device 1. The connection method between the module busbar 32 and the capacitor busbar 42, described later, suppresses the temperature rise of the module busbar 32, thereby reducing the thermal influence from the module busbar 32 to the control board 5 via air and electrical connection members. Furthermore, since the heat from the semiconductor module 3 is more easily dissipated to the cooler 2 via the capacitor 4, the thermal influence from the semiconductor module 3 to the control board 5 can be reduced.

[0037] <Connection Configuration Between Module Busbar 32 and Capacitor Busbar 42> The connection configuration between the module busbar 32 and the capacitor busbar 42, which is the core part of this disclosure, will now be described. Each of the multiple module busbars 32 has a different length from the busbar connection portion on one side connected to the capacitor busbar 42 to the module internal connection portion on the other side which is electrically connected to the internal part of the semiconductor module 3. Each of the multiple capacitor busbars 42 has a different thermal resistance from the capacitor connection portion which is electrically connected to the capacitor element 41 to the part of the cooler 2 to which the capacitor 4 is thermally connected. The longest module busbar 32, which is the module busbar with the longest length as described above, and the capacitor busbar 42 with the smallest thermal resistance as described above are electrically connected.

[0038] The specific configuration of this embodiment will be explained using Figure 3. The lower arm busbar 32b is connected to the negative electrode busbar 42b at the busbar connection part 32b1 and to the semiconductor chip 34 at the module internal connection part 32b2. The upper arm busbar 32a is connected to the positive electrode busbar 42a at the busbar connection part 32a1 and to the upper arm spreader 36 at the module internal connection part 32a2. The lower arm busbar 32b is directly bonded to the semiconductor chip 34 of the lower arm part 3b. Therefore, the lower arm busbar 32b is susceptible to heat from the semiconductor chip 34 and tends to become hotter than the upper arm busbar 32a. The module busbar 32 and the capacitor busbar 42 are electrically connected, for example, by welding. The connection between the module busbar 32 and the capacitor busbar 42 is not limited to welding; the busbars may be connected by other methods such as soldering, brazing, or screwing. The length of the module busbar 32 described above is the distance of the current path through which the current flows. The lower arm busbar 32b is longer than the upper arm busbar 32a, resulting in a larger current path. Therefore, the heat generated by the lower arm busbar 32b is greater than that generated by the upper arm busbar 32a. The lower arm busbar 32b is the longest module busbar. The lower arm busbar 32b generates a large amount of self-heat and is a module busbar 32 that is directly bonded to the semiconductor chip 34.

[0039] The positive busbar 42a is connected to the positive electrode 43a of the capacitor element 41 at the capacitor connection portion 42a1, and the negative busbar 42b is connected to the negative electrode 43b of the capacitor element 41 at the capacitor connection portion 42b1. The thermal resistance of the negative busbar 42b is the thermal resistance from the connection portion between the negative busbar 42b and the negative electrode 43b to the sealing resin 44, capacitor case 45, grease 61, and cooler 2. The thermal resistance of the positive busbar 42a is the thermal resistance from the connection portion between the positive busbar 42a and the positive electrode 43a to the positive electrode 43a, capacitor element 41, negative electrode 43b, sealing resin 44, capacitor case 45, grease 61, and cooler 2. Thus, the thermal resistance of the negative busbar 42b is smaller than the thermal resistance of the positive busbar 42a.

[0040] The lower arm busbar 32b, which is the longest module busbar with a large heat generation, is electrically connected to the negative electrode busbar 42b, which has low thermal resistance, and the upper arm busbar 32a, which generates little heat, is electrically connected to the positive electrode busbar 42a, which has high thermal resistance. In this way, the lower arm busbar 32b, which generates a large amount of heat, and the negative electrode busbar 42b, which has low thermal resistance, are electrically connected, so the heat that moves from the lower arm busbar 32b to the capacitor 4 can be dissipated to the cooler 2, thereby reducing the effect of heat moving from the semiconductor module 3 to the capacitor element 41. Because the effect of heat moving from the semiconductor module 3 to the capacitor element 41 is small, the temperature rise of the capacitor 4 can be suppressed. Also, if the temperature of the capacitor busbar 42 is higher than the temperature of the module busbar 32, heat can be dissipated from the capacitor 4 to the semiconductor module 3, thereby suppressing the temperature rise of the capacitor element 41. Furthermore, since the module busbar 32 and the capacitor busbar 42 are directly connected, no additional components are required to connect the module busbar 32 and the capacitor busbar 42, thus maintaining the miniaturization of the power converter 1.

[0041] In this embodiment, the upper arm portion 3a is positioned more adjacent to the capacitor 4 than the lower arm portion 3b when viewed perpendicular to the cooling surface 25a. The lower arm busbar 32b provided on the lower arm portion 3b is directly bonded to the semiconductor chip 34. Because the lower arm busbar 32b, which generates a large amount of heat, and the negative electrode busbar 42b, which has low thermal resistance, are electrically connected, the thermal influence from the semiconductor chip 34 to the capacitor element 41 can be reduced. Furthermore, because the junction between the lower arm busbar 32b and the semiconductor chip 34 is located away from the capacitor 4, the influence of heat transfer from this junction to the capacitor element 41 can be reduced.

[0042] As described above, in the power conversion device 1 according to Embodiment 1, each of the multiple module busbars 32 has a different length from the busbar connection portion on one side connected to the capacitor busbar 42 to the module internal connection portion on the other side which is electrically connected to the internal part of the semiconductor module 3. Each of the multiple capacitor busbars 42 has a different thermal resistance from the capacitor connection portion which is electrically connected to the capacitor element 41 to the part of the cooler 2 to which the capacitor 4 is thermally connected. Since the longest module busbar 32, which is the module busbar with the longest length, and the capacitor busbar 42 with the smallest thermal resistance are electrically connected, the heat moving from the longest module busbar to the capacitor 4 can be dissipated to the cooler 2, thus reducing the influence of heat moving from the semiconductor module 3 to the capacitor element 41. Because the influence of heat moving from the semiconductor module 3 to the capacitor element 41 is small, the temperature rise of the capacitor 4 can be suppressed. In addition, since the module busbar 32 and the capacitor busbar 42 are directly connected, no additional parts are required to connect the module busbar 32 and the capacitor busbar 42, so the miniaturization of the power conversion device 1 can be maintained.

[0043] If the AC current output busbar 33 is located on the opposite side of the semiconductor module 3 from the capacitor 4, and a semiconductor chip 34 is placed between it and the capacitor 4, the AC current output busbar 33 does not protrude in the Y direction, thus reducing the size of the semiconductor module 3 in the Y direction. As the size of the semiconductor module 3 in the Y direction is reduced, the size of the power converter 1 in the Y direction can be miniaturized.

[0044] When the semiconductor module 3 and the capacitor 4 are provided side by side on the cooling surface 25a of the cooler 2, and when the upper arm portion 3a is arranged at a position adjacent to the capacitor 4 rather than the lower arm portion 3b when viewed perpendicular to the cooling surface 25a, since the lower arm bus bar 32b with a large heat generation amount and the negative electrode bus bar 42b with a small thermal resistance are electrically connected, the thermal influence from the semiconductor chip 34 to the capacitor element 41 can be reduced. Also, since the joint portion between the lower arm bus bar 32b and the semiconductor chip 34 is kept away from the capacitor 4, the influence of the heat moving from this joint portion to the capacitor element 41 can be reduced.

[0045] When the semiconductor module 3 and the capacitor 4 are arranged on the cooling surface 25a which is one surface of the cooler 2, the dead space that occurs when the cooling surface 25a where the capacitor 4 is arranged and the cooling surface 25a where the semiconductor module 3 is arranged are at different heights can be eliminated. Therefore, large components such as a control board can be arranged in the height direction of the semiconductor module 3, and thus the power conversion device 1 can be miniaturized.

[0046] When the semiconductor module 3 and the capacitor 4 are provided side by side on the cooling surface 25a of the cooler 2, and when a plurality of semiconductor modules 3 are arranged side by side in the Y direction, since the semiconductor modules 3 can be arranged in parallel in the Y direction, the power conversion device 1 can be miniaturized.

[0047] When the control board 5 is arranged such that at least a part of it overlaps with the semiconductor module 3 when viewed perpendicular to the cooling surface 25a, a large control board 5 can be arranged without increasing the size of the cooler 2, and thus the power conversion device 1 can be miniaturized.

[0048] When the semiconductor module 3 is thermally connected to the cooling surface 25a of the cooler 2, and the cooler 2 has a flow path 21 for cooling the semiconductor module 3 through the portion provided with the cooling surface 25a, by providing the flow path 21, the semiconductor module 3 can be efficiently and forcibly cooled.

[0049] When the capacitor 4 is thermally connected to the cooling surface 25a of the cooler 2 via a heat dissipation member, the thermal resistance between the capacitor 4 and the cooler 2 can be reduced, allowing the heat generated in the capacitor element 41 and the heat transferred to the capacitor element 41 via the capacitor busbar 42 to be dissipated to the cooler 2 more efficiently. Furthermore, when the heat dissipation member is grease 61, the thickness of the grease 61 can be reduced compared to other heat dissipation members, thus reducing the distance between the capacitor case 45 and the cooling surface 25a. As the distance between the capacitor case 45 and the cooling surface 25a is reduced, the thermal resistance between the capacitor 4 and the cooler 2 can be further reduced.

[0050] Embodiment 2. The power converter 1 according to Embodiment 2 will now be described. Figure 4 is a plan view showing the main parts of the capacitor 4 and semiconductor module 3 of the power converter 1 according to Embodiment 2, showing the capacitor 4 and one semiconductor module 3. Figure 5 is a cross-sectional view of the power converter 1, which is a cross-sectional view of the power converter 1 cut at the same position as the A-A cross-section in Figure 1. The power converter 1 according to Embodiment 2 has a different configuration of the arrangement of the upper arm portion 3a and the lower arm portion 3b compared to Embodiment 1. The configuration that is equivalent to the configuration shown in Embodiment 1 will not be described.

[0051] <Semiconductor Module 3> As shown in Figure 4, the semiconductor module 3 and the capacitor 4 are arranged side by side on the cooling surface 25a of the cooler 2, and the lower arm portion 3b is positioned more adjacent to the capacitor 4 than the upper arm portion 3a when viewed perpendicular to the cooling surface 25a. The lower arm busbar 32b provided on the lower arm portion 3b is directly bonded to the semiconductor chip 34, so in addition to the self-heating of the lower arm busbar 32b, its temperature rises due to heat transfer from the semiconductor chip 34, and the heat transfer to the negative electrode busbar 42b connected to the lower arm busbar 32b also increases. However, by positioning the lower arm portion 3b closer to the capacitor 4, the length of the lower arm busbar 32b is shortened, and the current path of the lower arm busbar 32b is shortened, so the self-heating of the lower arm busbar 32b can be reduced. Since the self-heating of the lower arm busbar 32b is reduced, the effect of heat transfer from the semiconductor module 3 to the capacitor 4 can be reduced.

[0052] <Capacitor 4> In this embodiment, as shown in Figure 5, the opening 45a of the capacitor case 45 is provided in the Z direction. The direction in which the opening 45a of the capacitor case 45 is provided is not limited to this. In this embodiment, the heat dissipation member is a heat dissipation sheet 62. When a material that undergoes significant shape deformation, such as grease, is used as the heat dissipation member, the capacitor 4 repeatedly experiences high and low temperatures, and a pumping-out phenomenon occurs with long-term use, raising concerns about insufficient cooling performance. However, when a material with a stable shape, such as a heat dissipation sheet 62, is used as the heat dissipation member, the pumping-out phenomenon does not occur even with long-term use, so the cooling performance of the capacitor 4 can be stably maintained. Furthermore, when the heat dissipation member is a heat dissipation sheet 62, the effect of this disclosure in suppressing the temperature rise of the capacitor 4 can be maintained for a long period of time. In addition, because the heat dissipation sheet 62 has a stable shape, when the heat dissipation sheet 62 is placed in a predetermined location by human hands or robots during the assembly of the power conversion device 1 in the factory, the heat dissipation sheet 62 is less likely to lose its shape. Because the shape of the heat dissipation sheet 62 is less likely to collapse, the assembly of the power converter 1 becomes easier, and thus the productivity of the power converter 1 can be improved.

[0053] <Control Board 5> In this embodiment, the semiconductor module 3 and the capacitor 4 are arranged side by side on the cooling surface 25a of the cooler 2, and the control board 5 is positioned so that at least a portion of it overlaps with the capacitor 4 when viewed perpendicular to the cooling surface 25a. This configuration allows for the placement of a large control board 5 without increasing the size of the cooler 2, thus enabling miniaturization of the power conversion device 1. Furthermore, compared to the configuration of Embodiment 1 shown in Figure 3, the distance from the flow path 21 adjacent to the semiconductor module 3 to the portion of the cooling surface 25a to which the capacitor 4 is thermally connected can be reduced. Because the distance from the flow path 21 to the portion of the cooling surface 25a to which the capacitor 4 is thermally connected is reduced, the heat from the capacitor 4 can be easily dissipated into the flow path 21.

[0054] In this embodiment, the capacitor 4 has a control terminal 47 that connects the capacitor 4 to the control board 5. The temperature of the control terminal 47 is determined by the temperature of the capacitor busbar 42 on which the control terminal 47 is provided, as the self-heating of the control terminal 47 is minimal. By arranging the semiconductor module 3, capacitor 4, and control board 5 as shown in Figure 5, the temperature of the capacitor busbar 42 can be made lower, thereby reducing the influence of heat transfer from the capacitor 4 to the control board 5. Furthermore, the capacitor busbar 42, which has high thermal resistance up to the cooler 2, is close to the control board 5, so the capacitor busbar 42 and the control board 5 may be connected for purposes such as discharging the charge of the capacitor element 41. In this case, the influence of heat transfer from the capacitor busbar 42 to the control board 5 is expected, but since the capacitor busbar 42, which has high thermal resistance, is connected to the module busbar 32, which does not heat up easily, the influence of heat transfer from the capacitor busbar 42 to the control board 5 is reduced.

[0055] As described above, in the power conversion device 1 according to Embodiment 2, the lower arm portion 3b is positioned closer to the capacitor 4 than the upper arm portion 3a when viewed perpendicular to the cooling surface 25a. By positioning the lower arm portion 3b closer to the capacitor 4, the length of the lower arm busbar 32b is shortened, and the current path of the lower arm busbar 32b is shortened, thereby reducing the self-heating of the lower arm busbar 32b. Since the self-heating of the lower arm busbar 32b is reduced, the influence of heat transfer from the semiconductor module 3 to the capacitor 4 can be reduced.

[0056] When the semiconductor module 3 and the capacitor 4 are arranged side by side on the cooling surface 25a of the cooler 2, and the control board 5 is positioned so that at least a portion of it overlaps with the capacitor 4 when viewed perpendicular to the cooling surface 25a, a large control board 5 can be placed without increasing the size of the cooler 2, thus enabling miniaturization of the power conversion device 1. Furthermore, compared to the configuration of Embodiment 1 shown in Figure 3, the distance from the flow path 21 adjacent to the semiconductor module 3 to the portion of the cooling surface 25a to which the capacitor 4 is thermally connected can be shortened, allowing the heat from the capacitor 4 to be easily dissipated into the flow path 21.

[0057] When the heat dissipation component is a heat dissipation sheet 62, the heat dissipation sheet 62 maintains a stable shape, so the pumping-out phenomenon does not occur even after long-term use, and the cooling performance of the capacitor 4 can be stably maintained. In addition, when assembling the power converter 1 in a factory, the shape of the heat dissipation sheet 62 is less likely to be distorted when the heat dissipation sheet 62 is placed in a predetermined location by human hands or robots, making the assembly of the power converter 1 easier and thus improving the productivity of the power converter 1.

[0058] Embodiment 3. A power converter 1 according to Embodiment 3 will be described. Figure 6 is a cross-sectional view of the power converter 1, which is a cross-sectional view of the power converter 1 cut at the same position as the A-A cross-section in Figure 1. The power converter 1 according to Embodiment 3 has a different configuration of the arrangement of the flow path 21 than Embodiment 1. Configurations that are equivalent to those shown in Embodiment 1 or Embodiment 2 will not be described.

[0059] <Cooler 2> In this embodiment, the capacitor 4 is thermally connected to the cooling surface 25a of the cooler 2, and the cooler 2 has a flow path 21 that cools the capacitor 4 through the portion where the cooling surface 25a is provided. Both the semiconductor module 3 and the capacitor 4 are forcibly cooled by the flow path 21. By providing the flow path 21 in this way, both the semiconductor module 3 and the capacitor 4 can be efficiently forcibly cooled. A refrigerant flows through the flow path 21 to forcibly cool both the semiconductor module 3 and the capacitor 4. The refrigerant is, for example, a liquid such as water or ethylene glycol solution, or a gas such as air.

[0060] The refrigerant flows, for example, in the order of flow path inlet 24a, flow path 21, and flow path outlet 24b. In this embodiment, the flow path inlet 24a is located on the side of the condenser 4 that is perpendicular to the cooling surface 25a, compared to the flow path outlet 24b. With this configuration, the flow path 21 on the side of the flow path inlet 24a is supplied with low-temperature refrigerant before it cools the semiconductor module 3, so that the portion of the cooling surface 25a where the condenser 4 is located can also be cooled efficiently.

[0061] In this embodiment, a lower arm busbar 32b, which is directly bonded to the semiconductor chip 34 and has a long current path, is connected to the negative electrode busbar 42b of the capacitor 4. By arranging the flow path 21 adjacent to the cooling surface 25a to which the capacitor 4 is thermally connected, heat from the semiconductor module 3 is more easily dissipated into the flow path 21 compared to Embodiment 1, thereby reducing the influence of heat transfer from the semiconductor module 3 to the capacitor element 41.

[0062] <Semiconductor Module 3> In this embodiment, the longest module busbar, the lower arm busbar 32b, is electrically connected to the semiconductor chip 34 at the module internal connection portion 32b2, and the lower arm busbar 32b is thermally connected to the cooler 2 via a cooling block 37 in the portion between the busbar connection portion 32b1 and the module internal connection portion 32b2. In the configuration shown in Figure 6, the cooling block 37 is thermally connected to the cooler 2 via an insulating material 38, a copper plate 39, and a bonding material 31.

[0063] The cooling block 37 and the lower arm busbar 32b are joined by a bonding material such as solder, and the cooling block 37 and the insulating material 38 are joined by a bonding material such as solder. The cooling block 37 is made of aluminum or a metal with high thermal conductivity such as copper. In this embodiment, since the upper arm portion 3a is positioned closer to the capacitor 4 than the lower arm portion 3b, the length of the lower arm busbar 32b increases, and the amount of self-heat generated by the lower arm busbar 32b increases. However, by providing the cooling block 37, the path for dissipating the heat from the self-heating lower arm busbar 32b to the cooler 2 can be increased, so the influence of heat transfer from the semiconductor module 3 to the capacitor 4 can be further reduced.

[0064] As described above, in the power conversion device 1 according to Embodiment 3, the lower arm busbar 32b is electrically connected to the semiconductor chip 34 at the module internal connection part 32b2, and the lower arm busbar 32b is thermally connected to the cooler 2 via the cooling block 37 in the portion between the busbar connection part 32b1 and the module internal connection part 32b2. Therefore, the path for dissipating the heat from the lower arm busbar 32b, which generates a large amount of heat on its own, to the cooler 2 can be increased, and the influence of heat moving from the semiconductor module 3 to the capacitor 4 can be further reduced.

[0065] If the capacitor 4 is thermally connected to the cooling surface 25a of the cooler 2, and the cooler 2 has a flow path 21 that cools the capacitor 4 through the portion where the cooling surface 25a is provided, then both the semiconductor module 3 and the capacitor 4 are forcibly cooled by the flow path 21, so both the semiconductor module 3 and the capacitor 4 can be efficiently forcibly cooled.

[0066] Embodiment 4. The power converter 1 according to Embodiment 4 will now be described. Figure 7 is a cross-sectional view of the power converter 1, which is a cross-sectional view of the power converter 1 cut at the same position as the A-A cross-section in Figure 1. The power converter 1 according to Embodiment 4 has a configuration that includes a capacitor terminal 48 and a busbar heat dissipation member 6 in addition to the configuration shown in Embodiment 1. Configurations that are equivalent to those shown in Embodiment 1, Embodiment 2, or Embodiment 3 will not be described.

[0067] <Capacitor 4> In this embodiment, the capacitor 4 is electrically connected to the capacitor element 41 and has a plurality of capacitor terminals 48 that are exposed to the outside. Each of the plurality of capacitor busbars 42 is electrically connected to each of the capacitor terminals 48 and is electrically connected to the capacitor element 41 via the capacitor terminals 48. In the configuration shown in Figure 7, the positive busbar 42a is connected to the capacitor terminal 48 that is connected to the positive electrode 43a of the capacitor element 41. The negative busbar 42b is connected to the capacitor terminal 48 that is connected to the negative electrode 43b of the capacitor element 41. The capacitor terminals 48 protrude from the sealing resin 44 toward the open portion of the capacitor case 45. The capacitor terminals 48 and the capacitor busbars 42 are electrically connected by screws or welding.

[0068] With this configuration, when changing the shape of the capacitor busbar 42 due to a change in the connection configuration with the semiconductor module 3 or the configuration of the cooler 2, only the shape of the capacitor busbar 42 needs to be changed, without changing the part on the capacitor element 41 side, thus reducing the cost of the power converter 1. Since the part on the capacitor element 41 side can be used in common, the productivity of the power converter 1 can be improved.

[0069] In this embodiment, the capacitor busbar 42 is thermally connected to the cooler 2 via the busbar heat dissipation member 6. In the configuration shown in Figure 7, the negative electrode busbar 42b is thermally connected to the cooler 2 via the busbar heat dissipation member 6. A busbar heat dissipation member 6 may also be provided between the positive electrode busbar 42a and the cooler 2. The busbar heat dissipation member 6 is, for example, a heat dissipation sheet made of silicone. The busbar heat dissipation member 6 is not limited to a heat dissipation sheet made of silicone, but may also be grease, curing grease, or adhesive. The busbar heat dissipation member 6 has insulating properties to prevent short circuits between the cooler 2 and the negative electrode busbar 42b.

[0070] The negative electrode busbar 42b is connected to the lower arm busbar 32b. The lower arm busbar 32b is connected to the semiconductor chip 34 and is the longest module busbar with a long current path. Therefore, the heat generated in the lower arm busbar 32b, which is prone to overheating, is transferred to the negative electrode busbar 42b. By providing the busbar heat dissipation member 6, the heat generated in the lower arm busbar 32b is dissipated to the cooler 2 via the busbar heat dissipation member 6, thereby reducing the influence of heat transfer from the semiconductor module 3 to the capacitor element 41.

[0071] Furthermore, in this embodiment as well, the thermal resistance from each capacitor busbar 42 to the cooler 2 is the same as the thermal resistance described in Embodiment 1, so the thermal resistance of the negative electrode busbar 42b is smaller than the thermal resistance of the positive electrode busbar 42a. The negative electrode busbar 42b is connected to the lower arm busbar 32b, and the positive electrode busbar 42a is connected to the upper arm busbar 32a. In this embodiment, the lower arm busbar 32b, which is directly bonded to the semiconductor chip 34 and has a long current path that makes it easy to heat up, is connected to the negative electrode busbar 42b, which has a small thermal resistance to the cooler 2 among the capacitor busbars 42. As a result, the heat transferred from the lower arm busbar 32b to the capacitor 4 can be efficiently dissipated to the cooler 2. Because the heat transferred from the lower arm busbar 32b to the capacitor 4 is efficiently dissipated to the cooler 2, the influence of heat moving from the semiconductor module 3 to the capacitor element 41 can be reduced.

[0072] As described above, in the power conversion device 1 according to Embodiment 4, since the negative electrode busbar 42b is thermally connected to the cooler 2 via the busbar heat dissipation member 6, the heat generated in the lower arm busbar 32b is dissipated to the cooler 2 via the busbar heat dissipation member 6, thereby reducing the influence of heat transfer from the semiconductor module 3 to the capacitor element 41.

[0073] Each of the multiple capacitor busbars 42 is electrically connected to each of the capacitor terminals 48, and via the capacitor terminals 48, is electrically connected to the capacitor element 41. Therefore, when changing the shape of the capacitor busbars 42, only the shape of the capacitor busbars 42 needs to be changed, without changing the part on the capacitor element 41 side, thus reducing the cost of the power conversion device 1.

[0074] Furthermore, while this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the art disclosed in this specification. For example, these include modifying, adding, or omitting at least one component, or even extracting at least one component and combining it with a component from another embodiment.

[0075] 1 Power converter, 2 Cooler, 21 Flow path, 22 Forced cooling section, 23 Flow path forming section, 24 Refrigerant inlet / outlet, 24a Flow path inlet, 24b Flow path outlet, 25 Bottom wall, 25a Cooling surface, 3 Semiconductor module, 3a Upper arm section, 3b Lower arm section, 31 Bonding material, 32 Module busbar, 32a Upper arm busbar, 32a1 Busbar connection section, 32a2 Internal module connection section, 32b Lower arm busbar, 32b1 Busbar connection section, 32b2 Internal module connection section, 33 AC current output busbar, 34 Semiconductor chip, 35 Lower arm spreader, 36 Upper arm spreader, 37 Cooling block, 38 Insulating material, 39 Copper plate, 4 Capacitor, 41 Capacitor element, 42 Capacitor busbar, 42a Positive electrode busbar, 42a1 Capacitor connection section, 42b Negative busbar, 42b1 Capacitor connection part, 43 Capacitor electrode, 43a Positive electrode, 43b Negative electrode, 44 Sealing resin, 45 Capacitor case, 45a Opening, 47 Control terminal, 48 Capacitor terminal, 5 Control board, 6 Busbar heat dissipation member, 61 Grease, 62 Heat dissipation sheet

Claims

1. A power conversion device comprising: a capacitor having one or more capacitor elements and a plurality of capacitor busbars electrically connected to the capacitor elements; one or more semiconductor modules having a plurality of module busbars, one of which is electrically connected to each of the plurality of capacitor busbars; and a cooler for cooling the capacitor and the semiconductor modules, wherein each of the plurality of module busbars has a different length from the busbar connection portion on one side connected to the capacitor busbar to the internal module connection portion on the other side, which is electrically connected to the internal part of the semiconductor module; each of the plurality of capacitor busbars has a different thermal resistance from the capacitor connection portion electrically connected to the capacitor element to the part of the cooler to which the capacitor is thermally connected; and the longest module busbar, which is the module busbar with the longest length, and the capacitor busbar with the smallest thermal resistance are electrically connected.

2. The power conversion device according to claim 1, wherein the semiconductor module has one or more semiconductor chips and an AC current output busbar that outputs AC current, the semiconductor module and the capacitor are arranged side by side, and the AC current output busbar is on the side of the semiconductor module opposite to the capacitor, with the semiconductor chip sandwiched between it and the capacitor.

3. The power conversion device according to claim 1 or 2, wherein the semiconductor module has an upper arm portion that constitutes an upper arm and a lower arm portion that constitutes a lower arm, the semiconductor module and the capacitor are arranged side by side on the surface of the cooler, and the upper arm portion is positioned more adjacent to the capacitor than the lower arm portion when viewed perpendicular to the surface.

4. The power conversion device according to claim 1 or 2, wherein the semiconductor module has an upper arm portion that constitutes an upper arm and a lower arm portion that constitutes a lower arm, the semiconductor module and the capacitor are arranged side by side on the surface of the cooler, and the lower arm portion is positioned more adjacent to the capacitor than the upper arm portion when viewed perpendicular to the surface.

5. The power conversion device according to claim 1, wherein the semiconductor module and the capacitor are arranged on the same surface which is one of the surfaces of the cooler.

6. The power conversion device according to any one of claims 1 to 5, wherein the semiconductor module has one or more semiconductor chips, the longest module busbar is electrically connected to the semiconductor chips at the module internal connection portion, and the longest module busbar is thermally connected to the cooler via a cooling block in the portion between the busbar connection portion and the module internal connection portion.

7. A power conversion device according to any one of claims 1 to 6, comprising a plurality of semiconductor modules, wherein the semiconductor modules and the capacitors are arranged side by side on a surface having the cooler, and one direction parallel to the surface in which the semiconductor modules and the capacitors are arranged is defined as the X direction, and a direction parallel to the surface and perpendicular to the X direction is defined as the Y direction, and the plurality of semiconductor modules are arranged side by side in the Y direction.

8. A power conversion device according to any one of claims 1 to 7, comprising a control board, wherein the semiconductor module and the capacitor are arranged side by side on the surface of the cooler, and the control board, when viewed perpendicular to the surface, is arranged such that at least a portion of it overlaps with the capacitor.

9. A power conversion device according to any one of claims 1 to 7, comprising a control board, wherein the semiconductor module and the capacitor are arranged side by side on the surface of the cooler, and the control board, when viewed perpendicular to the surface, is arranged such that at least a portion of it overlaps with the semiconductor module.

10. The power conversion device according to any one of claims 1 to 9, wherein the semiconductor module is thermally connected to a surface of the cooler, and the cooler has a flow path for cooling the semiconductor module through the portion provided with the surface.

11. The power conversion device according to any one of claims 1 to 10, wherein the capacitor is thermally connected to a surface of the cooler, and the cooler has a flow path for cooling the capacitor through the portion provided with the surface.

12. The power conversion device according to any one of claims 1 to 11, wherein the capacitor is thermally connected to the surface of the cooler via a heat dissipation member.

13. The power conversion device according to any one of claims 1 to 12, wherein the capacitor busbar is thermally connected to the cooler via a busbar heat dissipation member.

14. The power conversion device according to claim 12, wherein the heat dissipation member is grease or a heat dissipation sheet.

15. The power conversion device according to any one of claims 1 to 14, wherein the capacitor has a plurality of capacitor terminals that are electrically connected to the capacitor element and exposed to the outside, and each of the plurality of capacitor busbars is electrically connected to each of the capacitor terminals and electrically connected to the capacitor element via the capacitor terminals.

Images