Power Conversion Device

Abstract

To provide a power conversion device capable of efficiently cooling a plurality of semiconductor modules even when arranging three or more semiconductor modules including switching elements on a common cooling surface.SOLUTION: A power conversion device 100 includes semiconductor modules 11, 12, and 13 each of which includes a switching element. The semiconductor modules 11 and 13 are arranged side by side on a cooling surface 81a in a α direction separated from each other. The semiconductor module 12 is arranged on the cooling surface 81a separated from the semiconductor modules 11 and 13 on a β direction side crossing the α direction.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a power conversion device, and more particularly to a power conversion device including a plurality of semiconductor modules. [Background technology]

[0002] BACKGROUND ART Conventionally, a power conversion device including a plurality of semiconductor modules is known (see, for example, Patent Document 1).

[0003] The power conversion device described in Patent Document 1 includes a plurality of semiconductor modules. In the plurality of semiconductor modules, two current switch circuits are arranged in series, each of which is made up of a parallel-connected circuit of a semiconductor element, such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and a diode. In the power conversion device described in Patent Document 1, four of the plurality of semiconductor modules are arranged vertically side by side so as to be in contact with a cooler. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 146179 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the power conversion device described in Patent Document 1, four semiconductor modules, each including a semiconductor element (switching element) that becomes a heat source through switching operation, are arranged vertically in a cooler, so the semiconductor modules are relatively close to each other. Therefore, when three or more semiconductor modules each including a switching element are arranged on a common cooling surface (cooler), the cooling efficiency of the semiconductor modules decreases.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a power conversion device that can efficiently cool multiple semiconductor modules, even when three or more semiconductor modules each having switching elements are arranged on a common cooling surface. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention one The power conversion device according to the aspect ,vinegar the cooling body has a cooling surface on which each of the semiconductor modules is arranged and cools each of the semiconductor modules arranged on the cooling surface; and a plurality of plate-shaped connecting conductors that electrically connect the semiconductor modules together, the plurality of semiconductor modules including a first semiconductor module, a second semiconductor module, and a third semiconductor module each having a switching element, the first semiconductor module and the third semiconductor module being arranged side by side in a first direction and spaced apart from each other on the cooling surface of the cooling body, the second semiconductor module being arranged on the cooling surface of the cooling body and spaced apart from the first semiconductor module and the third semiconductor module in a second direction that intersects with the first direction, and the plurality of connecting conductors being stacked while being insulated from each other.

[0008] This invention oneIn the power conversion device according to the above aspect, as described above, the first semiconductor module and the third semiconductor module are arranged side by side in the first direction at a distance from each other on the cooling surface of the cooling body. The second semiconductor module is arranged on the cooling surface of the cooling body at a distance from the first semiconductor module and the third semiconductor module in a second direction intersecting the first direction. This allows the first semiconductor module and the third semiconductor module to be arranged side by side in the first direction on a common cooling surface, and the second semiconductor module to be arranged side by side in the second direction intersecting the first direction. This allows the first semiconductor module, the second semiconductor module, and the third semiconductor module to be spaced apart on the cooling surface, and therefore the distance between the first semiconductor module, the second semiconductor module, and the third semiconductor module can be increased compared to when the first semiconductor module, the second semiconductor module, and the third semiconductor module are arranged side by side in the same direction on a common cooling surface. This allows the distance between the multiple switching elements that serve as heat sources included in each of the first semiconductor module, the second semiconductor module, and the third semiconductor module to be increased. As a result, the distance between the heat sources can be increased, and therefore the multiple semiconductor modules can be efficiently cooled even when three or more semiconductor modules having switching elements are arranged on a common cooling surface.

[0009] the above oneIn the power conversion device according to the above aspect, preferably, each of the first semiconductor module, the second semiconductor module, and the third semiconductor module has a rectangular parallelepiped shape having a rectangular cooled surface in contact with the cooling surface of the cooling body, the first semiconductor module and the third semiconductor module are arranged parallel to each other at a distance from each other with short sides of their cooled surfaces aligned along a first direction, and the second semiconductor module is arranged with short sides of its cooled surface aligned along a second direction perpendicular to the first direction. With this configuration, the rectangular cooled surface of the second semiconductor module and the rectangular cooled surfaces of the first semiconductor module and the third semiconductor module can be arranged perpendicular to each other. Therefore, unlike a case in which the second semiconductor module is arranged in a direction that diagonally intersects the parallel-arranged first semiconductor module and the third semiconductor module on the cooling surface, the distance from the second semiconductor module to the first semiconductor module and the distance from the second semiconductor module to the third semiconductor module can be made equal, thereby preventing imbalances in cooling efficiency between the first semiconductor module side and the third semiconductor module side. As a result, the plurality of semiconductor modules can be cooled evenly, and the semiconductor modules can be cooled efficiently.

[0010] the above oneThe power conversion device according to the above aspect preferably further includes a first power conversion group and a second power conversion group, each including a power conversion unit and configured to individually switch and output power, and the cooling body includes a plate-shaped cooling plate having one side serving as a cooling surface on which each of the semiconductor modules of the power conversion units included in the first power conversion group is arranged and the other side serving as a cooling surface on which each of the semiconductor modules of the power conversion units included in the second power conversion group is arranged. With this configuration, the first power conversion group and the second power conversion group, configured to individually switch and output power, can be cooled by arranging them on one side and the other side of a common cooling plate. Therefore, by using a common cooling plate while switching power output operations, the area of ​​the cooling surface of the cooling plate can be reduced compared to arranging the first power conversion group and the second power conversion group on the same side of a single cooling plate. As a result, the multiple semiconductor modules can be efficiently cooled while achieving a compact device configuration and a reduced number of components.

[0011] In this case, the cooling body preferably includes a heat dissipation unit that is connected to the cooling plate unit so as to be heat exchangeable and that is shared by the first power conversion group and the second power conversion group. With this configuration, the heat dissipation unit shared by the first power conversion group and the second power conversion group can be connected to the cooling plate unit so as to be heat exchangeable, thereby cooling multiple semiconductor modules. Therefore, by sharing the heat dissipation unit in addition to the cooling plate unit, it is possible to efficiently cool multiple semiconductor modules while further reducing the size of the device configuration and the number of components.

[0012] the above oneIn the power conversion device according to the above aspect, preferably, the first semiconductor module and the third semiconductor module each have one switching element, and the second semiconductor module has two switching elements. With this configuration, the first semiconductor module and the third semiconductor module each having one switching element can be arranged side by side in a first direction, and the second semiconductor module having two switching elements can be arranged spaced apart in a second direction different from the first direction in which the first semiconductor module and the third semiconductor module are arranged. Therefore, by arranging only the second semiconductor module, which has more heat sources, spaced apart in the second direction, which is different from the first direction, the multiple semiconductor modules can be arranged to prevent the multiple heat sources from being too close to each other. As a result, differences in the cooling efficiency of each semiconductor module by the cooling body can be prevented, thereby more efficiently cooling the multiple semiconductor modules.

[0013] the above oneIn the power conversion device according to this aspect, the plurality of connecting conductors preferably include a first plate-shaped connecting conductor electrically connecting the first semiconductor module and the second semiconductor module and a second plate-shaped connecting conductor electrically connecting the second semiconductor module and the third semiconductor module, the first connecting conductor and the second connecting conductor being stacked while being insulated from each other. With this configuration, the first connecting conductor and the second connecting conductor are stacked while being insulated from each other, so that a current flowing from the first semiconductor module to the second semiconductor module and a current flowing from the second semiconductor module to the third semiconductor module can flow adjacently and opposite to each other. Therefore, the currents flowing opposite to each other in the first connecting conductor and the second connecting conductor can reduce parasitic inductance generated in the first connecting conductor and the second connecting conductor. As a result, by arranging the first semiconductor module and the third semiconductor module side by side in a first direction and arranging the second semiconductor module at a distance in a second direction intersecting the first direction, and stacking the first connecting conductors and second connecting conductors connecting each of them on top of each other, it is possible to efficiently cool the multiple semiconductor modules and to suppress a decrease in power conversion efficiency due to parasitic inductance.

[0014] the above oneIn the power conversion device according to this aspect, preferably, the power conversion unit is configured to output power at three potential levels: an upper potential, an intermediate potential, and a lower potential, and further includes a smoothing capacitor module including a positive-side capacitor and a negative-side capacitor connected in series between the positive and negative sides of the input, smoothing the input power; a positive-side conductor electrically connecting the positive-side terminal of a first semiconductor module provided on the positive side to the positive-side terminal of the smoothing capacitor module connected to the positive side of the positive-side capacitor; an intermediate terminal of the smoothing capacitor module connected to the negative side of the positive-side capacitor and the positive side of the negative-side capacitor; an intermediate conductor electrically connecting the negative-side terminal of the first semiconductor module provided on the positive side to the positive terminal of a third semiconductor module provided on the negative side; and a negative-side conductor electrically connecting the negative terminal of the third semiconductor module provided on the negative side to the negative terminal of the smoothing capacitor module connected to the negative side of the negative-side capacitor, wherein the positive-side conductor, the intermediate conductor, and the negative-side conductor are stacked in this order while being insulated from each other. With this configuration, in a three-level inverter that outputs power at three potential levels, the positive conductor and the intermediate conductor can be stacked adjacent to each other, and the negative conductor and the intermediate conductor can be stacked adjacent to each other. Therefore, by opposing the current flowing through the positive conductor and the current flowing through the intermediate conductor, the parasitic inductance generated between the positive conductor and the intermediate conductor can be reduced. Furthermore, by opposing the current flowing through the negative conductor and the current flowing through the intermediate conductor, the parasitic inductance generated between the negative conductor and the intermediate conductor can be reduced. As a result, the parasitic inductance generated between the positive conductor, the intermediate conductor, and the negative conductor can be reduced, thereby enabling efficient cooling of multiple semiconductor modules in the three-level inverter and suppressing a decrease in power conversion efficiency due to parasitic inductance.

[0015] In this case, preferably, the smoothing capacitor module has a rectangular parallelepiped shape and is arranged to face the cooling surface of the cooling body on which each of the plurality of semiconductor modules is arranged, and the positive terminal, negative terminal, and intermediate terminal of the smoothing capacitor module are arranged on a common terminal arrangement surface adjacent to the surface facing the cooling surface in the first direction in the rectangular parallelepiped smoothing capacitor module, and the positive conductor, intermediate conductor, and negative conductor are L-shaped plates bent from the direction along the cooling surface to the direction along the terminal arrangement surface. With this configuration, because the positive conductor, intermediate conductor, and negative conductor are L-shaped plates bent from the direction along the cooling surface to the direction along the terminal arrangement surface, even when the plurality of semiconductor modules and the smoothing capacitor module are arranged closely to each other, the positive conductor, intermediate conductor, and negative conductor can be easily connected to the smoothing capacitor module on the terminal arrangement surface adjacent to the surface facing the cooling surface. Therefore, even when the plurality of semiconductor modules and the smoothing capacitor module are arranged closely to each other, the assembly work of connecting the terminals can be easily performed. As a result, by placing the plurality of semiconductor modules and the smoothing capacitor module close to each other, the device configuration can be made smaller and the workability of the assembly work can be improved.

[0016] the above oneIn the power conversion device according to this aspect, preferably, four intermediate terminals of the smoothing capacitor module are arranged in a row along the side of the terminal arrangement surface facing the cooling surface, two positive terminals of the smoothing capacitor module are arranged adjacent to each other, and two negative terminals of the smoothing capacitor module are arranged adjacent to each other, with each of the two positive terminals and two negative terminals arranged in a row on the terminal arrangement surface adjacent to each of the four intermediate terminals arranged in a row. With this configuration, the distance between the overlapping portions of the positive conductor and the negative conductor and the intermediate conductor can be made larger than when the positive terminals and the negative terminals are not arranged adjacent to the intermediate terminals. Therefore, the distance between the overlapping portions of the positive conductor and the negative conductor and the intermediate conductor can be made larger. As a result, the inductance generated in the positive conductor, the intermediate conductor, and the negative conductor can be made smaller, thereby further suppressing a decrease in power conversion efficiency.

[0017] the above oneThe power conversion device according to the above aspect preferably further includes a first-phase power conversion unit, a second-phase power conversion unit, and a third-phase power conversion unit, each including a power conversion section and outputting AC power of a respective phase of three-phase AC power, and the cooling body includes a first cooling body that cools each of the plurality of semiconductor modules included in the first-phase power conversion unit, a second cooling body that cools each of the plurality of semiconductor modules included in the second-phase power conversion unit, and a third cooling body that cools each of the plurality of semiconductor modules included in the third-phase power conversion unit. With this configuration, the plurality of semiconductor modules included in each of the first-phase power conversion unit, the second-phase power conversion unit, and the third-phase power conversion unit can be cooled by separate cooling bodies. Therefore, in each of the first-phase power conversion unit, the plurality of semiconductor modules can be arranged on their respective cooling bodies so as to be spaced apart from each other, thereby efficiently cooling the plurality of semiconductor modules having switching elements. Therefore, even when AC power of each phase of three-phase AC power is output separately, it is possible to efficiently cool a plurality of semiconductor modules having switching elements.

[0018] the above one In the power conversion device according to this aspect, the power conversion unit is preferably mounted on a railway vehicle and configured to output AC power to an auxiliary power line that supplies auxiliary power to the railway vehicle. With this configuration, even when AC power is output to the auxiliary power line that supplies auxiliary power to the railway vehicle, it is possible to efficiently cool the multiple semiconductor modules having switching elements in the power conversion unit. As a result, it is possible to supply a more stable auxiliary power to the railway vehicle. [Effects of the Invention]

[0019] According to the present invention, as described above, it is possible to provide a power conversion device that can efficiently cool multiple semiconductor modules, even when three or more semiconductor modules each having a switching element are arranged on a common cooling surface. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing a railway vehicle on which a power conversion device according to an embodiment of the present invention is mounted. [Figure 2] 1 is a schematic diagram for explaining the configuration of a power conversion device according to an embodiment of the present invention; [Figure 3] 1 is a circuit diagram of a power conversion device according to an embodiment of the present invention. [Figure 4] FIG. 4 is a circuit diagram of a first power conversion group in a first phase power conversion unit. [Figure 5] FIG. 1 is a diagram showing three semiconductor modules. [Figure 6] FIG. 2 is a schematic diagram for explaining the connection between a smoothing capacitor module and three semiconductor modules. [Figure 7] FIG. 2 is a perspective view illustrating the configuration of a cooling body. [Figure 8] 10A and 10B are diagrams for explaining the arrangement of semiconductor modules on the cooling surface of a cooling body. [Figure 9] FIG. 2 is a diagram showing the arrangement of terminals in a smoothing capacitor module. [Figure 10] FIG. 2 is a diagram illustrating a connecting conductor. [Figure 11] 10A and 10B are diagrams for explaining a connection between a semiconductor module and a smoothing capacitor module by a connecting conductor. [Figure 12] FIG. 3 is a diagram for explaining the arrangement of a first power conversion group and a second power conversion group. [Figure 13] FIG. 10 is a diagram showing the configuration of a smoothing capacitor module according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] The configuration of a power conversion device 100 according to this embodiment will be described with reference to Figures 1 to 12. The power conversion device 100 is mounted on a railway vehicle 101.

[0023] (Railway vehicle configuration) 1, railway vehicle 101 is configured to run on rails using power supplied from overhead lines 102, which serve as a DC power source. In the following description, the direction of travel of railway vehicle 101 is defined as the X direction, the left-right direction of railway vehicle 101 as the Y direction, and the up-down direction (vertical direction) of railway vehicle 101 as the Z direction.

[0024] The railway vehicle 101 includes a pantograph 101a, a circuit breaker 101b (see FIG. 3), an auxiliary power supply line 101c, a load 101d, and a power conversion device 100. The pantograph 101a receives (collects) power supplied to an overhead line 102. The circuit breaker 101b opens an electric circuit when an overcurrent occurs. The circuit breaker 101b includes, for example, a high-speed circuit breaker. The auxiliary power supply line 101c is a power supply line for supplying auxiliary power to the railway vehicle 101. Specifically, the auxiliary power supply line 101c is a power supply line for supplying power from the power conversion device 100 (described later) to the load 101d. The load 101d includes air conditioning equipment, control equipment, and the like mounted on the railway vehicle 101. The load 101d operates using AC power supplied from the power conversion device 100 via the auxiliary power supply line 101c.

[0025] The power conversion device 100 is an auxiliary power supply device that converts DC power from an overhead line 102 into three-phase AC power and supplies it to a load 101d. The power conversion device 100 is attached to the lower side (Z2 side) of the bottom of the body of the railway vehicle 101.

[0026] (Overall configuration of power conversion device) As shown in FIG. 2 , in this embodiment, the power conversion device 100 includes three power conversion units. Specifically, the power conversion device 100 includes a first-phase power conversion unit 100a, a second-phase power conversion unit 100b, and a third-phase power conversion unit 100c. The first-phase power conversion unit 100a, the second-phase power conversion unit 100b, and the third-phase power conversion unit 100c are configured to output three-phase AC power, respectively. Specifically, the first-phase power conversion unit 100a is configured to output U-phase AC power. The second-phase power conversion unit 100b is configured to output V-phase AC power. And the third-phase power conversion unit 100c is configured to output W-phase AC power.

[0027] As shown in Fig. 3, the power conversion device 100 is a standby redundant power conversion device configured to be able to switch between two power conversion operations, one on the first group side and the other on the second group side. The first-phase power conversion unit 100a includes a first power conversion group 1a and a second power conversion group 2a. The second-phase power conversion unit 100b includes a first power conversion group 1b and a second power conversion group 2b. The third-phase power conversion unit 100c includes a first power conversion group 1c and a second power conversion group 2c.

[0028] In this embodiment, the first power conversion group 1a and the second power conversion group 2a include power conversion units 10 and 20, respectively, that perform power conversion operations. The first power conversion group 1a and the second power conversion group 2a are configured to individually switch and output power. Specifically, the first-phase power conversion unit 100a that outputs U-phase AC power includes the first power conversion group 1a that outputs the U-phase and the second power conversion group 2a that outputs the U-phase. Similarly, the second-phase power conversion unit 100b that outputs the V-phase includes the first power conversion group 1b that outputs the V-phase and the second power conversion group 2b that outputs the V-phase. Similarly, the third-phase power conversion unit 100c that outputs the W-phase includes the first power conversion group 1c that outputs the W-phase and the second power conversion group 2c that outputs the W-phase. The first power conversion groups 1a, 1b, and 1c constitute the first group side, and the second power conversion groups 2a, 2b, and 2c constitute the second group side.

[0029] The first-phase power conversion unit 100a normally operates the first power conversion group 1a on the first group side without operating the second power conversion group 2a on the second group side, converts input DC power, and outputs U-phase AC power. The power conversion device 100 is configured to switch the output from the first power conversion group 1a to the output from the second power conversion group 2a if a malfunction such as a breakdown occurs in the first power conversion group 1a on the first group side. The second-phase power conversion unit 100b and the third-phase power conversion unit 100c are similarly configured to switch to the second group side and perform power conversion operation if a malfunction occurs on the first group side.

[0030] The power conversion device 100 also includes switches 3a, 3b, 3c, and 3d. The switches 3a to 3d are configured to open and close to switch between output from the first group side and output from the second group side. The power conversion device 100 makes the switches 3a and 3c conductive when operating the first group side (first power conversion groups 1a, 1b, and 1c) based on a control signal from a control unit (not shown). The power conversion device 100 makes the switches 3b and 3d conductive when operating the second group side (second power conversion groups 2a, 2b, and 2c) based on a control signal from the control unit. The switches 3a to 3d include, for example, electromagnetic contactors.

[0031] (power conversion unit) Next, the configuration of the first-phase power conversion unit 100a will be described with reference to Figures 2 to 12. Note that the second-phase power conversion unit 100b and the third-phase power conversion unit 100c have the same configuration as the first-phase power conversion unit 100a, and therefore descriptions thereof will be omitted.

[0032] 2 to 4, the first power conversion group 1a on the first group side of the first phase power conversion unit 100a includes a power conversion section 10, a smoothing capacitor module 30, and a connecting conductor 50. The second power conversion group 2a on the second group side of the first phase power conversion unit 100a includes a power conversion section 20, a smoothing capacitor module 40, and a connecting conductor 60.

[0033] 3 and 4, in this embodiment, the power conversion unit 10 is configured to output power at three potential levels: an upper potential, a middle potential, and a lower potential. Specifically, the power conversion unit 10 has a three-level inverter circuit that performs power conversion based on input between a positive side, which is a DC voltage input from a pantograph 101a, and a negative side, which is grounded, and outputs three potential levels. In this embodiment, the power conversion units 10 and 20 mounted on the railway vehicle 101 are configured to output AC power to an auxiliary power supply line 101c.

[0034] Semiconductor Module As shown in FIG. 5, the power conversion unit 10 of the first power conversion group 1a includes three semiconductor modules (semiconductor module 11, semiconductor module 12, and semiconductor module 13). The semiconductor module 11 has one switching element Q1. The semiconductor module 12 has two switching elements Q2 and Q3. The semiconductor module 13 has one switching element Q4. The switching elements Q1 to Q4 are, for example, IGBTs. The three semiconductor modules 11, 12, and 13 are examples of "plurality of semiconductor modules" in the claims. The semiconductor modules 11, 12, and 13 are examples of "first semiconductor module," "second semiconductor module," and "third semiconductor module," respectively.

[0035] In this embodiment, the semiconductor module 11 is provided on the positive side. The semiconductor module 11 has a switching circuit arranged on the positive side, in which a switching element Q1 and a diode D1 are connected in parallel, and a diode D2 arranged on the negative side. In the semiconductor module 11, the switching circuit arranged on the positive side and the diode D2 arranged on the negative side are connected in series. The semiconductor module 11 has terminals P1, C1, N1, and G1. The terminal P1 is connected to the positive side of the semiconductor module 11. The terminal N1 is connected to the negative side of the semiconductor module 11. The terminal C1 is connected between the switching circuit arranged on the positive side of the semiconductor module 11 and the diode D2 arranged on the negative side. The terminal G1 is connected to the gate terminal of the switching element Q1 to which a gate signal from a gate substrate 70 (described later) is input. The terminal P1 and the terminal N1 are examples of the "positive terminal of the first semiconductor module" and the "negative terminal of the first semiconductor module" in the claims, respectively.

[0036] In this embodiment, the semiconductor module 12 has two switching circuits: a switching circuit arranged on the positive side in which the switching element Q2 and the diode D3 are connected in parallel, and a switching circuit arranged on the negative side in which the switching element Q3 and the diode D4 are connected in parallel. The two switching circuits are connected in series in the semiconductor module 12. The semiconductor module 12 has terminals P2, C2, N2, G2, and G3. The terminal P2 is connected to the positive side of the semiconductor module 12. The terminal N2 is connected to the negative side of the semiconductor module 12. The terminal C2 is connected between the switching circuit arranged on the positive side and the switching circuit arranged on the negative side of the semiconductor module 12. The terminal G2 is connected to the gate terminal of the switching element Q2 to which a gate signal from a gate substrate 70 (described later) is input. Similarly, the terminal G3 is connected to the gate terminal of the switching element Q3 to which a gate signal from a gate substrate 70 (described later) is input.

[0037] In this embodiment, the semiconductor module 13 is provided on the negative side. The semiconductor module 13 has a diode D5 arranged on the positive side and a switching circuit arranged on the negative side to which the switching element Q4 and the diode D6 are connected in parallel. In the semiconductor module 13, the diode D5 arranged on the positive side and the switching circuit arranged on the negative side are connected in series. The semiconductor module 13 has terminals P3, C3, N3, and G4. The terminal P3 is connected to the positive side of the semiconductor module 13. The terminal N3 is connected to the negative side of the semiconductor module 13. The terminal C3 is connected between the diode D5 arranged on the positive side of the semiconductor module 13 and the switching circuit arranged on the negative side. The terminal G4 is connected to the gate terminal of the switching element Q4 to which a gate signal from a gate substrate 70 (described later) is input. The terminals P3 and N3 are examples of the "positive terminal of the third semiconductor module" and the "negative terminal of the third semiconductor module" in the claims, respectively.

[0038] As shown in FIGS. 2 and 4, the first-phase power conversion unit 100a includes a gate substrate 70. The gate substrate 70 outputs gate signals for controlling the switching operations of the switching elements Q1 to Q4 based on control signals from a control unit (not shown). The gate signals are, for example, pulse width modulation (PWM) signals. The gate substrate 70 also outputs gate signals to the power conversion units 20 of the second power conversion group 2a on the second group side. The gate substrate 70 is arranged along the XZ plane on the Y1-direction side of the first-phase power conversion unit 100a.

[0039] <Smoothing capacitor module> As shown in FIG. 4, the smoothing capacitor module 30 of the first power conversion group 1a includes a capacitor 31 and a capacitor 32. In this embodiment, the smoothing capacitor module 30 smoothes the input power. The capacitors 31 and 32 are configured to be connected in series between the positive and negative sides of the input in the first power conversion group 1a. Specifically, the smoothing capacitor module 30 is configured such that the capacitor 31 is connected to the positive side and the capacitor 32 is connected to the negative side. The capacitors 31 and 32 are, for example, film capacitors. The capacitor 31 is an example of a "positive side capacitor" in the claims. The capacitor 32 is an example of a "negative side capacitor" in the claims.

[0040] The smoothing capacitor module 30 also has terminals P4, C4, and N4. The terminal P4 is connected to the positive electrode side of the smoothing capacitor module 30. That is, the terminal P4 is connected to the positive electrode side of the capacitor 31. The terminal N4 is connected to the negative electrode side of the smoothing capacitor module 30. That is, the terminal N4 is connected to the negative electrode side of the capacitor 32. The terminal C4 is an intermediate terminal of the smoothing capacitor module 30. That is, the terminal C4 is connected between the capacitor 31 and the capacitor 32. Specifically, the terminal C4 is connected to the negative electrode side of the capacitor 31 and the positive electrode side of the capacitor 32.

[0041] Electrical connection between semiconductor module and capacitor As shown in FIGS. 4 and 6, the connecting conductor 50 electrically connects the power conversion unit 10 (semiconductor modules 11 to 13) and the smoothing capacitor module 30. Specifically, the connecting conductor 50 includes conductors 51, 52, 53, 54, and 55. Note that the conductor 51 is an example of a "first connecting conductor" in the claims. The conductor 52 is an example of a "second connecting conductor" in the claims. The conductor 53 is an example of a "positive side conductor" in the claims. The conductor 54 is an example of an "intermediate conductor" in the claims. The conductor 55 is an example of a "negative side conductor" in the claims.

[0042] In this embodiment, the conductor 51 electrically connects the semiconductor module 11 and the semiconductor module 12. Specifically, the conductor 51 connects the terminal C1 of the semiconductor module 11 and the terminal P2 of the semiconductor module 12. Furthermore, the conductor 52 electrically connects the semiconductor module 12 and the semiconductor module 13. Specifically, the conductor 52 connects the terminal N2 of the semiconductor module 12 and the terminal C3 of the semiconductor module 13.

[0043] In this embodiment, the conductor 53 electrically connects the terminal P1 of the semiconductor module 11 provided on the positive electrode side to the terminal P4 of the smoothing capacitor module 30. The conductor 53 is also electrically connected to the positive electrode side of the input. The conductor 54 electrically connects the terminal C4 of the smoothing capacitor module 30, the terminal N1 of the semiconductor module 11 provided on the positive electrode side, and the terminal P3 of the semiconductor module 13 provided on the negative electrode side. The conductor 55 electrically connects the terminal N3 of the semiconductor module 13 provided on the negative electrode side to the terminal N4 of the smoothing capacitor module 30.

[0044] As described above, the first power conversion group 1a configures a three-level inverter circuit with the power conversion unit 10, the smoothing capacitor module 30, and the connecting conductor 50. The second power conversion group 2a on the second group side configures a three-level inverter circuit with an electrically similar configuration to the first power conversion group 1a on the first group side. That is, the power conversion unit 20, the smoothing capacitor module 40, and the connecting conductor 60 on the second group side have electrically similar configurations to the power conversion unit 10, the smoothing capacitor module 30, and the connecting conductor 50, respectively.

[0045] <Cooling body> As shown in FIG. 2 , in this embodiment, the power conversion device 100 includes a cooling element 80. The cooling element 80 cools each of the semiconductor modules (U-phase semiconductor modules 11-13 and V-phase and W-phase semiconductor modules). The cooling element 80 includes a cooling element 80a, a cooling element 80b, and a cooling element 80c. The cooling element 80a cools each of the semiconductor modules (semiconductor modules 11-13) included in the first-phase power conversion unit 100a. The cooling element 80b cools each of the semiconductor modules included in the second-phase power conversion unit 100b. The cooling element 80c cools each of the semiconductor modules included in the third-phase power conversion unit 100c. The cooling element 80a is an example of a “first cooling element” in the claims. The cooling element 80b is an example of a “second cooling element” in the claims. Cooling body 80c is an example of the "third cooling body" in the claims.

[0046] As shown in FIG. 7 , in this embodiment, the cooling element 80a has a cooling plate portion 81, a heat dissipation portion 82, and a refrigerant pipe 83. In this embodiment, the cooling plate portion 81 of the cooling element 80a is a plate-shaped member having a cooling surface 81a and a cooling surface 81b. A plurality of semiconductor modules are arranged on the cooling surfaces 81a and 81b. The cooling element 80a cools each of the plurality of semiconductor modules arranged on the cooling surfaces 81a and 81b. Specifically, a plurality of semiconductor modules 11 to 13 of the power conversion unit 10 included in the first power conversion group 1a (first group side) are arranged on the cooling surface 81a. A plurality of semiconductor modules of the power conversion unit 20 included in the second power conversion group 2a (second group side) are arranged on the cooling surface 81b. That is, the cooling plate portion 81 of the cooling element 80a is used in common by the first power conversion group 1a on the first group side and the second power conversion group 2a on the second group side. The cooling surface 81a is an example of the "one side" and "cooling surface" in the claims, and the cooling surface 81b is an example of the "other side" and "cooling surface" in the claims.

[0047] Similarly to the cooling plate section 81, the heat dissipation section 82 is used in common by the first power conversion group 1a and the second power conversion group 2a. The heat dissipation section 82 is configured to be able to exchange heat with the cooling plate section 81. The heat dissipation section 82 has a plurality of plate-shaped fins. The heat dissipation section 82 is configured to cool the power conversion section 10 of the first power conversion group 1a and the power conversion section 20 of the second power conversion group 2a by exchanging heat with the surrounding air by natural convection via the plurality of plate-shaped fins.

[0048] The refrigerant pipe 83 has a refrigerant flow path through which cooling water, which is the refrigerant, flows. The cooling water in the refrigerant pipe 83 is heated on the cooling plate section 81 side and vaporizes. The heated cooling water is then cooled on the heat dissipation section 82 side and returns to liquid. This allows heat exchange between the cooling plate section 81 and the heat dissipation section 82. Note that the cooling body 80a is tilted 7 degrees from the horizontal plane (XY plane) (see FIGS. 7 and 8) so that the cooling water that has returned to liquid flows into the cooling plate section 81 side due to gravity, and so that the cooling plate section 81 side is lower than the heat dissipation section 82 side.

[0049] Like the cooling body 80a, the cooling body 80b and the cooling body 80c are configured to commonly cool the first group side and the second group side of the second phase power conversion unit 100b and the third phase power conversion unit 100c, respectively.

[0050] <Layout of each part of the power conversion unit> As shown in FIGS. 7 and 8, the semiconductor modules 11 to 13 of the power conversion unit 10 are arranged on the cooling surface 81a of the cooling body 80a. In this embodiment, the semiconductor modules 11 and 13 are arranged side by side in the α direction (see FIG. 8) on the cooling surface 81a of the cooling body 80a, spaced apart from each other. The semiconductor module 12 is arranged on the cooling surface 81a of the cooling body 80a, spaced apart from the semiconductor modules 11 and 13 in the β direction (see FIG. 8) that intersects with the α direction. The α direction is an example of a "first direction" in the claims. The β direction is an example of a "second direction" in the claims.

[0051] Specifically, in this embodiment, the semiconductor modules 11, 12, and 13 each have a rectangular parallelepiped shape. The semiconductor modules 11, 12, and 13 each have a rectangular cooled surface 11a, 12a, and 13a (see FIG. 7) that contacts the cooling surface 81a of the cooling body 80a. The semiconductor modules 11 to 13 are fixed to the cooling surface 81a with fastening members such as screws (not shown). The semiconductor modules 11 and 13 are arranged parallel to each other and spaced apart from each other so that the short sides 11b and 13b (see FIG. 8) of the cooled surfaces 11a and 13a are aligned along the α direction. The semiconductor module 12 is arranged so that the short side 12b (see FIG. 8) of the cooled surface 12a is aligned along the β direction, which is perpendicular to the α direction. Specifically, the semiconductor module 11 is arranged on the heat dissipation unit 82 side (Y2 direction side) of the cooling body 80a in the α direction. The semiconductor module 13 is disposed on the gate substrate 70 side in the α direction (Y1 direction side). The semiconductor module 12 is disposed on the vertically upward side (Z1 direction side). The short side 11b of the semiconductor module 11 and the short side 13b of the semiconductor module 13 are disposed so as to align on a straight line along the α direction. The two short sides 12b of the semiconductor module 12 are disposed so as to align on a straight line along the β direction with the long side 11c of the semiconductor module 11 (see FIG. 8) and the long side 13c of the semiconductor module 13 (see FIG. 8), respectively. As a result, the semiconductor modules 11 to 13 are configured so that holes into which fastening members such as screws are inserted on the long side 11c and 13c sides of the semiconductor modules 11 and 13 and holes into which fastening members such as screws are inserted on the short side 12b side of the semiconductor module 12 are disposed so as to align on a straight line, thereby facilitating assembly work.

[0052] Since the cooling plate 81 (cooling body 80a) is tilted at 7 degrees from the horizontal plane, the α direction in which the semiconductor modules 11 and 13 are arranged side by side is tilted at 7 degrees from the Y direction. Similarly, the β direction is tilted at 7 degrees from the Z direction (vertical direction).

[0053] 8, in semiconductor module 11, terminals N1, P1, N1, P1, and C1 are arranged in a row in this order along the β direction from the Z1 direction (semiconductor module 12 side) toward the Z2 direction. Similarly, in semiconductor module 13, terminals N3, P3, N3, P3, and C3 are arranged in a row in this order along the β direction from the Z1 direction (semiconductor module 12 side) toward the Z2 direction. In semiconductor module 12, terminals N2, P2, N2, P2, and C2 are arranged in a row in this order along the α direction from the Y1 direction toward the Y2 direction (heat dissipation section 82 side of cooling body 80a). In addition, terminal G1 of semiconductor module 11 and terminal G4 of semiconductor module 13 are arranged on the Z2 direction side (the side opposite to semiconductor module 12). The terminals G2 and G3 of the semiconductor module 12 are arranged on the Y2 direction side (the heat dissipation portion 82 side of the cooling body 80a).

[0054] As shown in Fig. 9, in this embodiment, the smoothing capacitor module 30 has a rectangular parallelepiped shape. The smoothing capacitor module 30 is disposed so as to face a cooling surface 81a of a cooling body 80a on which each of the semiconductor modules 11 to 13 is disposed. Specifically, the smoothing capacitor module 30 is disposed so that the surface 30a in Fig. 9 faces the cooling surface 81a. The surface 30a has a rectangular shape, and is disposed so that each side extends along the α direction and the β direction. The surface 30a is an example of a "surface facing a cooling surface" in the claims.

[0055] The smoothing capacitor module 30 also has a surface 30b adjacent to the surface 30a. In this embodiment, the surface 30b is the surface adjacent to the surface 30a in the α direction in the rectangular parallelepiped-shaped smoothing capacitor module 30. Specifically, the surface 30b is arranged on the opposite side of the surface 30a in the α direction from the side on which the heat dissipation section 82 of the cooling body 80a is arranged (the Y1 direction side). The surface 30b is an example of a "terminal arrangement surface" in the claims.

[0056] In this embodiment, the terminals P4, C4, and N4 of the smoothing capacitor module 30 are arranged on a common surface 30b. Specifically, four terminals C4 are arranged in a row on the surface 30b along the side on the surface 30a side (along the β direction). Two terminals P4 of the smoothing capacitor module 30 are arranged adjacent to each other. Similarly, two terminals N4 of the smoothing capacitor module 30 are arranged adjacent to each other. Each of the two terminals P4 and the two terminals N4 is arranged in a row on the surface 30b so as to be adjacent to each of the four terminals C4 arranged in a row.

[0057] Specifically, four terminals C4 are arranged in a row along the side of the surface 30b facing in the X2 direction. Two terminals P4 and two terminals N4 are arranged in this order in a row along the side of the surface 30b facing in the X1 direction. The four terminals C4 are electrically at the same potential (see FIG. 4), but inside the smoothing capacitor module 30, the terminals C4 on the capacitor 31 side (the two terminals C4 arranged on the Z1 direction side) and the terminals C4 on the capacitor 32 side (the two terminals C4 arranged on the Z2 direction side) are not electrically connected (insulated). Therefore, the first group side smoothing capacitor module 30 and the second group side smoothing capacitor module 40 can be configured using a common module without changing the orientation of the modules.

[0058] As shown in FIGS. 10 and 11 , in this embodiment, conductors 51 and 52 are plate-shaped. Conductors 51 and 52 are stacked while being insulated from each other. Specifically, conductors 51 and 52 are stacked between surface 30a of smoothing capacitor module 30 and cooling surface 81a of cooling plate portion 81 of cooling body 80a. Conductors 53, 54, and 55 are L-shaped plates bent from a direction along surface 30a to a direction along surface 30b of smoothing capacitor module 30. That is, conductors 53 to 55 are plate-shaped bent from a direction along the YZ plane to the X direction. Conductors 53, 54, and 55 are stacked in this order while being insulated from each other.

[0059] 11, conductors 51 and 52 and conductors 53, 54, and 55 are similarly stacked and insulated from one another. Conductors 51 to 55 are laminated bus bars, each made of a metal conductor such as aluminum with an insulating film sheet laminated thereon. Conductor 51 connects to terminal C1 of semiconductor module 11 in the area indicated by dotted line L1 in FIG. 11, and to terminal P2 of semiconductor module 12 in the area indicated by dotted line L2 in FIG. 11. Conductor 52 connects to terminal C3 of semiconductor module 13 in the area indicated by dotted line L3 in FIG. 11, and to terminal N2 of semiconductor module 12 in the area indicated by dotted line L2 in FIG. 11. Conductor 53 connects to terminal P1 of semiconductor module 11 in the area indicated by dotted line L1 in FIG. 11, and to terminal P4 of smoothing capacitor module 30 in the area indicated by dotted line L4 in FIG. 11. Furthermore, the conductor 54 is connected to the terminal N1 of the semiconductor module 11 in the region of dotted line L1 in Fig. 11, is connected to the terminal P3 of the semiconductor module 13 in the region of dotted line L3 in Fig. 11, and is connected to the terminal C4 of the smoothing capacitor module 30 in the region of dotted line L4 in Fig. 11. Furthermore, the conductor 55 is connected to the terminal N3 of the semiconductor module 13 in the region of dotted line L3 in Fig. 11, and is connected to the terminal N4 of the smoothing capacitor module 30 in the region of dotted line L4 in Fig. 11.

[0060] 12, the power conversion units 20, smoothing capacitor modules 40, and connecting conductors 60 on the second group side are arranged symmetrically with the power conversion units 10, smoothing capacitor modules 30, and connecting conductors 50 on the first group side, respectively. The inputs and outputs of the first-phase power conversion unit 100a are connected by connecting conductors (bus bars) (not shown). The gate terminals (terminals G1 to G4) of the semiconductor modules 11 to 13 and the gate substrate 70 are connected by conductors (not shown).

[0061] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0062] In this embodiment, the semiconductor module 11 (first semiconductor module) and the semiconductor module 13 (third semiconductor module) are arranged side by side in the α direction (first direction) on the cooling surface 81a of the cooling body 80a and spaced apart from each other. The semiconductor module 12 (second semiconductor module) is arranged on the cooling surface 81a of the cooling body 80a and spaced apart from the semiconductor modules 11 and 13 in the β direction (second direction) intersecting with the α direction. As a result, on the common cooling surface 81a, the semiconductor modules 11 and 13 are arranged side by side in the α direction, and the semiconductor module 12 is arranged apart from each other on the β direction intersecting with the α direction. Therefore, the distance between the semiconductor modules 11, 12, and 13 on the cooling surface 81a can be made larger than when the semiconductor modules 11, 12, and 13 are arranged side by side in the same direction and placed on the common cooling surface 81a. This makes it possible to increase the distance between the multiple switching elements Q1 to Q4 that serve as heat sources included in each of semiconductor module 11, semiconductor module 12, and semiconductor module 13. As a result, since the distance between the heat sources can be increased, the multiple semiconductor modules (semiconductor modules 11 to 13) can be efficiently cooled even when three or more multiple semiconductor modules (semiconductor modules 11 to 13) are arranged on a common cooling surface 81a or when three or more multiple semiconductor modules (semiconductor modules 11 to 13) having switching elements Q1 to Q4 are arranged on the common cooling surface 81a.

[0063] In this embodiment, semiconductor module 11 (first semiconductor module), semiconductor module 12 (second semiconductor module), and semiconductor module 13 (third semiconductor module) each have a rectangular parallelepiped shape having rectangular cooled surfaces 11a-13a that contact cooling surface 81a of cooling body 80a, and semiconductor module 11 and semiconductor module 13 are arranged parallel to each other and spaced apart so that short sides 11b and 13b of cooled surfaces 11a and 13a are aligned along the α direction (first direction), and semiconductor module 12 is arranged so that short side 12b of cooled surface 12a is aligned along the β direction (second direction) that is perpendicular to the α direction. This allows rectangular cooled surface 12a of semiconductor module 12 and rectangular cooled surfaces 11a and 13a of semiconductor module 11 and semiconductor module 13 to be aligned perpendicular to each other. Therefore, unlike when semiconductor module 12 is arranged in a direction that diagonally intersects semiconductor module 11 and semiconductor module 13 that are arranged in parallel on cooling surface 81a, the distance from semiconductor module 12 to semiconductor module 11 and the distance from semiconductor module 12 to semiconductor module 13 can be made equal. This makes it possible to prevent imbalances in cooling efficiency between the semiconductor module 11 side and the semiconductor module 13 side. As a result, the plurality of semiconductor modules 11 to 13 can be cooled evenly, and therefore semiconductor modules 11 to 13 can be cooled efficiently.

[0064] Moreover, in this embodiment, the system further includes a first power conversion group 1a and a second power conversion group 2a, each of which includes power conversion units 10 and 20 and is configured to individually switch and output electric power, and the cooling body 80a includes a plate-shaped cooling plate unit 81 having a cooling surface 81a (one side) on which each of the plurality of semiconductor modules 11 to 13 of the power conversion unit 10 included in the first power conversion group 1a is arranged, and a cooling surface 81b (other side) on which each of the plurality of semiconductor modules of the power conversion unit 20 included in the second power conversion group 2a is arranged. As a result, the first power conversion group 1a and the second power conversion group 2a, which are configured to individually switch and output electric power, can be cooled by being placed on the cooling surface 81a and the cooling surface 81b of the common cooling plate unit 81. Therefore, by using a common cooling plate section 81 while switching the power output operation, it is possible to reduce the area of ​​the cooling surface 81a (cooling surface 81b) of the cooling plate section 81, compared to when the first power conversion group 1a and the second power conversion group 2a are arranged on the same surface of one cooling plate section 81. As a result, it is possible to efficiently cool multiple semiconductor modules while miniaturizing the device configuration and reducing the number of parts.

[0065] Furthermore, in this embodiment, the cooling body 80a is connected to the cooling plate section 81 so as to be able to exchange heat, and includes a heat dissipation section 82 that is used in common by the first power conversion group 1a and the second power conversion group 2a. Thus, by connecting the heat dissipation section 82 that is used in common to the cooling plate section 81 that is used in common by the first power conversion group 1a and the second power conversion group 2a so as to be able to exchange heat, it is possible to cool a plurality of semiconductor modules. Therefore, by sharing the heat dissipation section 82 in addition to the cooling plate section 81, it is possible to efficiently cool a plurality of semiconductor modules while further reducing the size of the device configuration and the number of parts.

[0066] In this embodiment, the semiconductor module 11 (first semiconductor module) and the semiconductor module 13 (third semiconductor module) each have one switching element Q1 (Q4), and the semiconductor module 12 (second semiconductor module) has two switching elements Q2 and Q3. This allows the semiconductor module 11 and the semiconductor module 13, each having one switching element Q1 (Q4), to be arranged side by side in the α direction (first direction), while the semiconductor module 12, having two switching elements Q2 and Q3, can be arranged spaced apart in the β direction (second direction), which is different from the α direction along which the semiconductor modules 11 and 13 are arranged. Therefore, by arranging only the semiconductor module 12 with many heat sources spaced apart in the β direction, which is a different direction, the multiple semiconductor modules (semiconductor modules 11-13) can be arranged so as to prevent the multiple heat sources from being too close to each other. As a result, differences in the cooling efficiency of the cooling element 80a among the semiconductor modules 11-13 can be prevented, thereby more efficiently cooling the multiple semiconductor modules 11-13.

[0067] Furthermore, this embodiment further includes a plate-shaped conductor 51 (first connecting conductor) that electrically connects the semiconductor module 11 (first semiconductor module) and the semiconductor module 12 (second semiconductor module), and a plate-shaped conductor 52 (second connecting conductor) that electrically connects the semiconductor module 12 and the semiconductor module 13 (third semiconductor module), and the conductors 51 and 52 are stacked while being insulated from each other. As a result, since the conductors 51 and 52 are stacked while being insulated from each other, the current flowing from the semiconductor module 11 toward the semiconductor module 12 and the current flowing from the semiconductor module 12 toward the semiconductor module 13 can flow adjacently and opposite to each other. Therefore, the currents flowing opposite to each other in the conductors 51 and 52 can reduce the parasitic inductance generated in the conductors 51 and 52. As a result, by arranging semiconductor module 11 and semiconductor module 13 side by side in the α direction (first direction) and arranging semiconductor module 12 at a distance in the β direction (second direction) that intersects with the α direction, and stacking the conductors 51 and 52 that connect them to each other, it is possible to efficiently cool multiple semiconductor modules 11 to 13 and to suppress a decrease in power conversion efficiency due to parasitic inductance.

[0068] In this embodiment, the power conversion units 10 and 20 are configured to output power at three levels of potential: an upper potential, an intermediate potential, and a lower potential, and include a capacitor 31 (positive-side capacitor) and a capacitor 32 (negative-side capacitor) connected in series between the positive and negative sides of the input, a smoothing capacitor module 30 that smoothes the input power, a conductor 53 (positive-side conductor) that electrically connects a terminal P1 (positive-side terminal) of the semiconductor module 11 (first semiconductor module) provided on the positive side and a terminal P4 (positive-side terminal) of the smoothing capacitor module 30 that is connected to the positive side of the capacitor 31, and a negative-side conductor that electrically connects a terminal P5 (positive-side terminal) of the smoothing capacitor module 30 that is connected to the positive side of the capacitor 31. and a conductor 54 (intermediate conductor) electrically connecting terminal C4 (intermediate terminal) of smoothing capacitor module 30 connected to the positive side of capacitor 32, terminal N1 (negative terminal) of semiconductor module 11 provided on the positive side, and terminal P3 (positive terminal) of semiconductor module 13 (third semiconductor module) provided on the negative side, and a conductor 55 (negative conductor) electrically connecting terminal N3 (negative terminal) of semiconductor module 13 provided on the negative side, and terminal N4 (negative terminal) of smoothing capacitor module 30 connected to the negative side of capacitor 32, where conductors 53, 54, and 55 are stacked in this order while being insulated from each other. This allows conductors 53 and 54 to be stacked adjacent to each other, and conductors 55 and 54 to be stacked adjacent to each other, in a three-level inverter that outputs power of three levels of potential. Therefore, by opposing the current flowing through conductor 53 and the current flowing through conductor 54, it is possible to reduce the parasitic inductance generated between conductors 53 and 54, and by opposing the current flowing through conductor 55 and the current flowing through conductor 54, it is possible to reduce the parasitic inductance generated between conductors 55 and 54. As a result, it is possible to reduce the parasitic inductance generated between conductors 53, 54, and 55, and therefore in the three-level inverter, it is possible to efficiently cool the multiple semiconductor modules 11 to 13 and to suppress a decrease in power conversion efficiency due to parasitic inductance.

[0069] In addition, in this embodiment, the smoothing capacitor module 30 has a rectangular parallelepiped shape and is arranged to face the cooling surface 81a of the cooling body 80a on which each of the multiple semiconductor modules 11 to 13 is arranged, and terminal P4 (positive side terminal), terminal N4 (negative side terminal), and terminal C4 (intermediate terminal) of the smoothing capacitor module 30 are arranged on a common surface 30b (terminal arrangement surface) adjacent to the surface 30a (surface facing the cooling surface 81a) in the α direction (first direction) of the smoothing capacitor module 30 having a rectangular parallelepiped shape, and the conductor 53 (positive side conductor), conductor 54 (intermediate side conductor), and conductor 55 (negative side conductor) are L-shaped plates bent from the direction along the cooling surface 81a to the direction along the surface 30b. As a result, conductors 53, 54, and 55 are L-shaped plates bent from the direction along cooling surface 81a to the direction along surface 30b, so even when the plurality of semiconductor modules 11-13 and the smoothing capacitor module 30 are arranged close to each other, conductors 53, 54, and 55 can be easily connected to the smoothing capacitor module 30 on surface 30b adjacent to surface 30a facing cooling surface 81a. Therefore, even when the plurality of semiconductor modules 11-13 and the smoothing capacitor module 30 are arranged close to each other, the assembly work of connecting the terminals can be easily performed. As a result, by bringing the plurality of semiconductor modules 11-13 and the smoothing capacitor module 30 close to each other, the device configuration can be made more compact and the workability of the assembly work can be improved.

[0070] Furthermore, in this embodiment, four terminals C4 (intermediate terminals) of the smoothing capacitor module 30 are arranged in a row on the surface 30b (terminal arrangement surface) along the edge on the side of the surface 30a (the surface facing the cooling surface 81a). Two terminals P4 (positive terminals) of the smoothing capacitor module 30 are arranged adjacent to each other, and two terminals N4 (negative terminals) of the smoothing capacitor module 30 are arranged adjacent to each other. Each of the two terminals P4 and the two terminals N4 is arranged in a row on the surface 30b adjacent to each of the four terminals C4 arranged in a row. This allows for a larger distance between the overlapping portions of the conductor 53 (positive conductor) and the conductor 55 (negative conductor) and the conductor 54 (intermediate conductor) compared to when the terminals P4 and N4 are not arranged adjacent to the terminal C4. This allows for a larger distance between the overlapping portions of the conductors 53 and 55 and the conductor 54, where currents flow. As a result, the inductance generated in the conductors 53, 54, and 55 can be further reduced, and therefore the decrease in power conversion efficiency can be further suppressed.

[0071] In this embodiment, the power conversion system further includes a first-phase power conversion unit 100a, a second-phase power conversion unit 100b, and a third-phase power conversion unit 100c, each of which includes a power conversion section and outputs AC power of one phase of the three-phase AC power, and the cooling body 80 includes a cooling body 80a (first cooling body) that cools each of the semiconductor modules included in the first-phase power conversion unit 100a, a cooling body 80b (second cooling body) that cools each of the semiconductor modules included in the second-phase power conversion unit 100b, and a cooling body 80c (third cooling body) that cools each of the semiconductor modules included in the third-phase power conversion unit 100c. This allows the semiconductor modules included in each of the first-phase power conversion unit 100a, the second-phase power conversion unit 100b, and the third-phase power conversion unit 100c to be cooled by the separate cooling bodies 80 (80a to 80c). Therefore, in each of the first-phase power conversion unit 100a, the second-phase power conversion unit 100b, and the third-phase power conversion unit 100c, the semiconductor modules can be arranged in the respective cooling bodies 80a-80c so as to increase the distance between them, thereby efficiently cooling the semiconductor modules having switching elements. Therefore, even when AC power of each phase of three-phase AC power is output separately, the semiconductor modules having switching elements can be efficiently cooled.

[0072] Furthermore, in this embodiment, the power conversion unit 10 is mounted on the railway vehicle 101 and is configured to output AC power to an auxiliary power supply line 101c for supplying auxiliary power to the railway vehicle 101. With this configuration, even when AC power is output to the auxiliary power supply line 101c for supplying auxiliary power to the railway vehicle 101, it is possible to efficiently cool the multiple semiconductor modules 11-13, each having switching elements Q1-Q4, in the power conversion unit 10. As a result, a more stable auxiliary power can be supplied to the railway vehicle 101.

[0073] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0074] For example, in the above embodiment, an example has been shown in which semiconductor module 11 (first semiconductor module) and semiconductor module 13 (third semiconductor module) are arranged parallel to and spaced apart from each other so that short sides 11b and 13b of cooled surfaces 11a and 13a are aligned along the α direction (first direction), and semiconductor module 12 is arranged so that short side 12b of cooled surface 12a is aligned along the β direction (second direction) perpendicular to the α direction, but the present invention is not limited to this. For example, in the present invention, the α direction in which semiconductor modules 11 and 13 are aligned side by side and the β direction in which semiconductor module 12 is aligned apart do not have to be perpendicular to each other.

[0075] In the above embodiment, the cooling body 80a includes the plate-shaped cooling plate portion 81 having the cooling surface 81a (one side) for cooling the first power conversion group 1a and the cooling surface 81b (other side) for cooling the second power conversion group 2a, but the present invention is not limited to this. For example, the first power conversion group 1a and the second power conversion group 2a may be configured to be cooled by a common cooling surface.

[0076] In the above embodiment, an example has been shown in which the heat dissipation unit 82 is used in common for the first power conversion group 1a and the second power conversion group 2a, but the present invention is not limited to this. For example, two heat dissipation units used separately for the first power conversion group 1a and the second power conversion group 2a may be included.

[0077] In the above embodiment, the heat dissipation unit 82 includes air-cooled heat dissipation fins, but the present invention is not limited to this. For example, the heat dissipation unit 82 may be a water-cooled type.

[0078] In the above embodiment, the semiconductor module 11 (first semiconductor module) and the semiconductor module 13 (third semiconductor module) each have one switching element Q1 (Q4), and the semiconductor module 12 (second semiconductor module) has two switching elements Q2 and Q3, but the present invention is not limited to this. For example, the first semiconductor module may have two switching elements, and the second semiconductor module and the third semiconductor module may each have one switching element. Furthermore, the first semiconductor module, the second semiconductor module, and the third semiconductor module may each have two switching elements.

[0079] In the above embodiment, the conductor 51 (first connecting conductor) and the conductor 52 (second connecting conductor) are stacked in a mutually insulated state, but the present invention is not limited to this. For example, the conductor 51 and the conductor 52 may be arranged parallel to each other and not stacked.

[0080] In the above embodiment, the power conversion unit 10 is configured as a three-level inverter circuit that outputs power at three potential levels: an upper potential, an intermediate potential, and a lower potential. However, the present invention is not limited to this. For example, the power conversion unit may be configured as a two-level three-phase inverter circuit or a two-level three-phase converter circuit. In this case, each of the three semiconductor modules may include two switching elements. In this case, a first group side and a second group side two-level three-phase inverter or two-level three-phase converter may be disposed on each of the two cooling surfaces of the cooling plate portion of the cooling body. Furthermore, the two first group side and the two second group side two-level three-phase inverters or two-level three-phase converters may be connected in parallel to a single load or power source, or may be connected to two different loads or power sources.

[0081] Furthermore, in the above embodiment, the terminals of the smoothing capacitor module 30 are commonly arranged on the surface 30b (terminal arrangement surface) on the gate substrate 70 side (Y1 direction side), but the present invention is not limited to this. For example, the smoothing capacitor module may be configured so that the terminals are arranged on the surface on the heat dissipation section (heat dissipation fin) side opposite the gate substrate side. The smoothing capacitor module may also be configured so that the terminals are arranged on the surface on the vertically upper side or vertically lower side. The smoothing capacitor module may also be configured so that the terminals are not arranged together on one common surface, but are arranged separately on two or more different surfaces.

[0082] In the above embodiment, the two terminals P4 (positive terminals) and two terminals N4 (negative terminals) of the smoothing capacitor module 30 are arranged in a row on the surface 30b (terminal arrangement surface) adjacent to each of the four terminals C4 (intermediate terminals) arranged in a row, but the present invention is not limited to this. For example, as in a smoothing capacitor module 230 according to a modified example shown in FIG. 13, the positive terminal P204, the intermediate terminal C204, and the negative terminal N204 may be arranged in this order in two rows. Note that arranging the terminals as in the smoothing capacitor module 30 according to the embodiment allows for a longer overlapping portion of the connecting conductors compared to the smoothing capacitor module 230 according to the modified example, thereby further reducing the parasitic inductance of the connecting conductors.

[0083] In the above embodiment, an example was shown in which the first-phase power conversion unit 100a, the second-phase power conversion unit 100b, and the third-phase power conversion unit 100c were provided, each of which outputs AC power of one phase of the three-phase AC power, but the present invention is not limited to this. For example, a single power conversion unit may be provided and configured to output three-phase AC power.

[0084] In the above embodiment, the power conversion unit 10 (20) is mounted on the railcar 101 and configured to output AC power to the auxiliary power supply line 101c for supplying auxiliary power to the railcar 101, but the present invention is not limited to this. For example, the power conversion unit 10 (20) may be configured to supply power for driving the railcar 101. Furthermore, the power conversion unit 10 (20) may be configured to be mounted on a vehicle such as an electric vehicle instead of a railcar. Furthermore, the power conversion unit 10 (20) may be configured to supply power to a stationary electric motor instead of a vehicle.

[0085] In the above embodiment, the semiconductor module 12 (second semiconductor module) is disposed vertically above (in the Z1 direction) the semiconductor module 11 (first semiconductor module) and the semiconductor module 13 (third semiconductor module), but the present invention is not limited to this. For example, the second semiconductor module may be disposed vertically below the first semiconductor module and the third semiconductor module. Furthermore, the semiconductor module 11 and the semiconductor module 13 may be disposed vertically, and the semiconductor module 12 may be disposed so as to be spaced apart from each other in the horizontal direction. [Explanation of symbols]

[0086] 1a, 1b, 1c First power conversion group 2a, 2b, 2c 2nd power conversion group 10, 20 Power conversion section 11 Semiconductor module (first semiconductor module, multiple semiconductor modules) 11a Cooled surface 11b Short side 12 semiconductor module (second semiconductor module, multiple semiconductor modules) 12a Cooled surface 12b Short side 13 Semiconductor module (third semiconductor module, multiple semiconductor modules) 13a Cooled surface 13b Short side 30, 40, 230 smoothing capacitor module 30a surface (surface facing the cooling surface) Surface 30b (terminal placement surface) 31 Capacitor (positive side capacitor) 32 Capacitor (negative side capacitor) 51 Conductor (first connecting conductor) 52 Conductor (second connecting conductor) 53 Conductor (positive conductor) 54 Conductor (Intermediate Conductor) 55 Conductor (negative conductor) 80, 80a, 80b, 80c cooling body 81 Cooling plate section 82 Heat radiation part 81a Cooling surface (one side) 81b Cooling surface (other side) 100 Power conversion device 100a Phase 1 Power Conversion Unit 100b Second phase power conversion unit 100c 3 Phase Power Conversion Unit 101 Railway Vehicles 101c Auxiliary Power Line

Claims

1. a power conversion unit including a plurality of semiconductor modules each having a switching element; a cooling body having a cooling surface on which each of the plurality of semiconductor modules is arranged, the cooling body cooling each of the plurality of semiconductor modules arranged on the cooling surface; a plurality of plate-shaped connecting conductors that electrically connect the plurality of semiconductor modules to each other, the plurality of semiconductor modules include a first semiconductor module, a second semiconductor module, and a third semiconductor module, each of which has the switching element; the first semiconductor module and the third semiconductor module are arranged side by side in a first direction and spaced apart from each other on the cooling surface of the cooling body, the second semiconductor module is disposed on the cooling surface of the cooling body, spaced apart from the first semiconductor module and the third semiconductor module in a second direction intersecting the first direction, A power conversion device, wherein the plurality of connecting conductors are stacked while being insulated from each other.

2. each of the first semiconductor module, the second semiconductor module, and the third semiconductor module has a rectangular parallelepiped shape having a rectangular cooled surface in contact with the cooling surface of the cooling body; the first semiconductor module and the third semiconductor module are arranged parallel to each other and spaced apart from each other so that short sides of the cooled surfaces are aligned along the first direction, The power conversion device according to claim 1 , wherein the second semiconductor module is arranged such that a short side of the cooled surface is aligned along the second direction perpendicular to the first direction.

3. further comprising a first power conversion group and a second power conversion group each including the power conversion unit and configured to individually switch and output power; 3. The power conversion device according to claim 1, wherein the cooling body includes a plate-shaped cooling plate portion having one side which is the cooling surface on which each of the plurality of semiconductor modules of the power conversion unit included in the first power conversion group is arranged, and another side which is the cooling surface on which each of the plurality of semiconductor modules of the power conversion unit included in the second power conversion group is arranged.

4. The power conversion device according to claim 3 , wherein the cooling body is connected to the cooling plate portion so as to be able to exchange heat, and includes a heat dissipation portion used in common by the first power conversion group and the second power conversion group.

5. each of the first semiconductor module and the third semiconductor module includes one of the switching elements; 5. The power conversion device according to claim 1, wherein the second semiconductor module has two of the switching elements.

6. The plurality of connecting conductors are a plate-shaped first connection conductor that electrically connects the first semiconductor module and the second semiconductor module; a plate-shaped second connection conductor that electrically connects the second semiconductor module and the third semiconductor module, The power conversion device according to claim 1 , wherein the first connecting conductor and the second connecting conductor are stacked in a state insulated from each other.

7. the power conversion unit is configured to output power at three levels of potential: an upper potential, an intermediate potential, and a lower potential; a smoothing capacitor module including a positive-side capacitor and a negative-side capacitor connected in series between the positive and negative sides of the input, for smoothing the input power; a positive-side conductor that electrically connects a positive-side terminal of the first semiconductor module provided on the positive electrode side and a positive-side terminal of the smoothing capacitor module that is connected to the positive electrode of the positive-side capacitor; an intermediate terminal of the smoothing capacitor module connected to the negative side of the positive-side capacitor and the positive side of the negative-side capacitor, an intermediate conductor electrically connecting the negative terminal of the first semiconductor module provided on the positive side and the positive terminal of the third semiconductor module provided on the negative side; a negative-side conductor that electrically connects a negative-side terminal of the third semiconductor module provided on the negative electrode side and a negative-side terminal of the smoothing capacitor module that is connected to the negative side of the negative electrode-side capacitor, The power conversion device according to any one of claims 1 to 6, wherein the positive conductor, the intermediate conductor, and the negative conductor are stacked in this order while being insulated from each other.

8. the smoothing capacitor module has a rectangular parallelepiped shape and is disposed so as to face the cooling surface of the cooling body on which each of the plurality of semiconductor modules is disposed; the positive terminal, the negative terminal, and the intermediate terminal of the smoothing capacitor module are arranged on a common terminal arrangement surface adjacent to a surface facing the cooling surface on the first direction side in the smoothing capacitor module having a rectangular parallelepiped shape, The power conversion device according to claim 7 , wherein the positive conductor, the intermediate conductor, and the negative conductor are L-shaped plates bent from a direction along the cooling surface to a direction along the terminal arrangement surface.

9. four intermediate terminals of the smoothing capacitor module are arranged in a row along a side of the terminal arrangement surface facing the cooling surface, The positive terminals of the smoothing capacitor module are arranged adjacent to each other, The negative terminals of the smoothing capacitor module are arranged in pairs adjacent to each other, 9. The power conversion device according to claim 8, wherein each of the two positive terminals and the two negative terminals is arranged in a row on the terminal arrangement surface so as to be adjacent to each of the four intermediate terminals arranged in a row.

10. the power converter further includes a first-phase power conversion unit, a second-phase power conversion unit, and a third-phase power conversion unit, each of which includes the power conversion unit and outputs AC power of each phase of the three-phase AC power; 10. The power conversion device according to claim 1, wherein the cooling body includes a first cooling body that cools each of the plurality of semiconductor modules included in the first-phase power conversion unit, a second cooling body that cools each of the plurality of semiconductor modules included in the second-phase power conversion unit, and a third cooling body that cools each of the plurality of semiconductor modules included in the third-phase power conversion unit.

11. The power conversion device according to any one of claims 1 to 10, wherein the power conversion unit is mounted on a railway vehicle and configured to output AC power to an auxiliary power line for supplying auxiliary power to the railway vehicle.

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