Power conversion device

Abstract

To obtain a power conversion device which suppresses heat evolution of wiring on an ON side to reduce a heat damage to a component connected with the wiring on the ON side.SOLUTION: A power conversion device comprises: a power conversion unit having switching elements on a positive electrode side and switching elements on a negative electrode side, provided with a plurality of arms for one phase to which AC current is output from connection parts of both elements, and in which arms of a plurality of phases are formed; a control unit which outputs either of a phase short circuit signal for turning all the switching elements on the positive electrode side on and turning all the switching elements on the negative electrode side off or a phase short circuit signal for turning all the switching elements on the negative electrode side on and turning all the switching elements on the positive electrode side off when AC current is stopped; first wiring which connects among a plurality of switching elements on the positive electrode side or among the switching elements on the negative electrode side all of which are turned on; and second wiring which connects among a plurality of switching elements on the positive electrode side or among the switching elements on the negative electrode side all of which are turned off, wherein heat resistance of the first wiring is smaller than heat resistance of the second wiring.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Recently, automobiles equipped with electric powertrains, such as hybrid automobiles, plug-in hybrid automobiles, electric automobiles, and fuel cell automobiles (hereinafter referred to as "electric vehicles"), have become widespread. In addition to, or instead of, the components of a conventional vehicle powered by an internal combustion engine, an electric motor for driving the wheels and an inverter circuit, which is a power conversion device for driving the electric motor, are installed in an electric vehicle. In an electric vehicle, the electric motor is operated in power running mode to generate driving torque during driving, and is operated in regenerative mode to generate regenerative braking torque during braking.

[0003] The drive system of an electric vehicle is composed of a DC power supply consisting of a secondary battery such as a lithium-ion battery, an inverter circuit connected to the DC power supply and consisting of a smoothing capacitor and multiple semiconductor switching elements, a control unit that controls the inverter circuit, and a rotating electric machine connected to the inverter circuit as a load. When multiple drive systems are installed, such as separate front and rear wheels, multiple inverter circuits and rotating electric machines are connected to the DC power supply. In addition, auxiliary equipment such as an air conditioner, a cooling mechanism, and a battery heater are also connected to the DC power supply.

[0004] The drive system of an electric vehicle is provided with a switching device that disconnects the battery, which is a DC power source, from the inverter circuit as needed to protect the battery from overvoltage and overcurrent. The conditions for opening the switching device include when the battery voltage exceeds a predetermined value during regenerative operation of the rotating electric machine (OV, overvoltage), when the battery voltage falls below a predetermined value due to battery depletion (UV, undervoltage), and when the current flowing through the battery exceeds a predetermined value (OC, overcurrent). Furthermore, the switching device may also be opened due to a vehicle breakdown, collision, or the like.

[0005] The battery is also equipped with a fuse connected in series with the battery. If the inverter circuit and various accessories connected to the battery short-circuit, a large current will flow through the fuse, causing the fuse to blow and disconnect the battery. In this case, too, the inverter circuit and the battery will be disconnected.

[0006] In such an abnormal state where the battery and the inverter circuit are open-circuited, it has been proposed to execute a phase short-circuit process in which all of the switching elements on the positive side or all of the switching elements on the negative side of the inverter circuit are turned on to short-circuit the phases of the rotating electric machine with each other.By executing the phase short-circuit process, the phase current of the rotating electric machine is stopped within the inverter circuit, and power is not regenerated on the input side of the inverter circuit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-47055 Summary of the Invention [Problem to be solved by the invention]

[0008] Patent Document 1 proposes a method for preventing regeneration of power to the inverter circuit's input side by performing phase short-circuit processing during an abnormality, stopping the phase current of a rotating electric machine within the inverter circuit. In this method, when a phase short-circuit occurs, all of the positive-side switching elements or all of the negative-side switching elements are turned on, resulting in a current flowing through the ON-side wiring connecting all of the positive-side switching elements turned on or all of the negative-side switching elements turned on. Meanwhile, no current flows through the ON-side wiring connecting all of the negative-side switching elements turned off or all of the positive-side switching elements turned off. Therefore, compared to normal inverter operation, a large current flows through the ON-side wiring for a long time during phase short-circuit operation, causing the ON-side wiring to heat up. The heat generated by the ON-side wiring is transferred to peripheral components, such as smoothing capacitors, connected to the ON-side wiring, potentially exceeding the heat resistance temperature of the peripheral components, resulting in damage to the peripheral components.

[0009] Therefore, an object of the present disclosure is to obtain a power conversion device that suppresses heat generation in the ON-side wiring during phase short-circuit driving and reduces thermal damage to components connected to the ON-side wiring. [Means for solving the problem]

[0010] The power conversion device of the present disclosure has a positive-side switching element electrically connected on one side to the positive-side side of a DC power supply, and a negative-side switching element connected in series on one side to the other side of the positive-side switching element and electrically connected on the other side to the negative-side side of the DC power supply, and a power conversion unit having a plurality of arms for one phase from which AC is output from a connection part that is a part connected in series between the other side of the positive-side switching element and one side of the negative-side switching element, and in which arms for multiple phases are formed, and a phase short-circuit signal that turns on all of the positive-side switching elements and turns off all of the negative-side switching elements when AC output from the power conversion unit is stopped, or a control unit that outputs one of the phase short-circuit signals that turns on all of the positive-side switching elements and turns off all of the positive-side switching elements to the drive units for the positive-side switching elements and the negative-side switching elements; first wiring that connects one side of the plurality of positive-side switching elements that are all turned on in the multi-phase arms or the other side of the plurality of negative-side switching elements that are all turned on in the multi-phase arms; and second wiring that connects one side of the plurality of positive-side switching elements that are all turned off in the multi-phase arms or the other side of the plurality of negative-side switching elements that are all turned off, and the thermal resistance of the first wiring is smaller than the thermal resistance of the second wiring. [Effects of the Invention]

[0011] According to the power conversion device of the present disclosure, the power conversion device includes a power conversion unit having positive and negative switching elements, each of which has a plurality of arms for one phase through which AC is output from a connection between the elements, forming multiple phase arms; a control unit that outputs, when stopping the AC, either a phase short-circuit signal that turns on all of the positive switching elements and turns off all of the negative switching elements, or a phase short-circuit signal that turns on all of the negative switching elements and turns off all of the positive switching elements; first wiring connecting the plurality of positive switching elements or negative switching elements that are all turned on; and second wiring connecting the plurality of positive switching elements or negative switching elements that are all turned off. Since the thermal resistance of the first wiring is smaller than the thermal resistance of the second wiring, heat generation in the first wiring, which is the ON-side wiring through which a large current flows for a long time during phase short-circuit operation, is suppressed. Because heat generation in the first wiring, which is the ON-side wiring during phase short-circuit operation, is suppressed, thermal damage to components connected to the first wiring is reduced. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of a circuit configuration of a power conversion device according to a first embodiment. [Figure 2] 1 is a plan view showing an outline of a power conversion device according to a first embodiment. [Figure 3] 3 is a cross-sectional view of the power converter taken along the line AA in FIG. 2. [Figure 4] 3 is a cross-sectional view of the power converter taken along the line BB in FIG. 2. [Figure 5] 3 is a diagram illustrating a current path when the power conversion device according to the first embodiment is driven by a phase short circuit. FIG. [Figure 6] FIG. 4 is a cross-sectional view of a power conversion device according to a modification of the first embodiment. [Figure 7] FIG. 10 is a plan view of a power conversion device according to a modification of the first embodiment. [Figure 8] FIG. 10 is a plan view of a power conversion device according to a modification of the first embodiment. [Figure 9]FIG. 4 is a cross-sectional view of a power conversion device according to a modification of the first embodiment. [Figure 10] FIG. 10 is a plan view of a power conversion device according to a modification of the first embodiment. [Figure 11] FIG. 10 is a plan view of a power conversion device according to a modification of the first embodiment. [Figure 12] FIG. 10 is a plan view of a power conversion device according to a modification of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a power conversion device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the same or equivalent members and parts in each drawing will be denoted by the same reference numerals.

[0014] Embodiment 1 FIG. 1 is a diagram showing an outline of the circuit configuration of a power conversion device 100 according to a first embodiment, illustrating the configuration of a drive system 101 of an electric vehicle as an example. FIG. 2 is a plan view showing an outline of the power conversion device 100. FIG. 3 is a cross-sectional view of the power conversion device 100 taken along the line AA in FIG. 2. FIG. 4 is a cross-sectional view of the power conversion device 100 taken along the line BB in FIG. 2. FIG. 5 is a diagram illustrating a current path when the power conversion device 100 is driven by a phase short circuit, in which the current path is added to the plan view of FIG. 2. The power conversion device 100 is, for example, a device that converts an input current from DC to AC, AC to DC, or an input voltage to a different voltage. In this embodiment, the power conversion device 100 will be described as an inverter, but the power conversion device 100 is not limited to an inverter.

[0015] <Electric Vehicle Drive System 101> An example of the configuration of a drive system 101 for an electric vehicle including a power conversion device 100 will be described with reference to FIG. 1. The drive system 101 for an electric vehicle includes the power conversion device 100, a DC power supply 70, a rotating electric machine 72, and an auxiliary machine 74. In FIG. 1, the left side is the input side and the right side is the output side. The DC power supply 70 is connected to the input side of the power conversion device 100. The DC power supply 70 is, for example, a secondary battery such as a lithium-ion battery. The rotating electric machine 72, which serves as a load, is connected to the output side of the power conversion device 100. The power conversion device 100 includes a smoothing capacitor 20, multiple semiconductor switching elements, and a control unit 73. The power conversion device 100 converts DC power from the DC power supply 70 into predetermined AC power by turning the multiple semiconductor switching elements on and off at a predetermined switching frequency, thereby adjusting the torque and rotation speed of the rotating electric machine 72. The rotating electric machine 72 can also function as a generator depending on its operation, charging the DC power supply 70 with regenerative power generated by the power generation. Note that a highly efficient permanent magnet three-phase synchronous rotating electric machine is often used as the rotating electric machine 72 applied to an electric vehicle. Here, a three-phase synchronous rotating electric machine will be described as an example, but the AC output of the rotating electric machine 72 and the power conversion device 100 is not limited to three phases. The technology disclosed herein can be applied to a power conversion device 100 with three or more phases. The auxiliary machine 74 is a device connected to the DC power supply 70, and is, for example, an air conditioner, a cooling mechanism, or a battery heater.

[0016] <Power conversion device 100> An example of the main circuit configuration of a power conversion device 100 will be described with reference to Fig. 1. A direct current is supplied to the power conversion device 100 from a direct current power supply 70. The power conversion device 100 has a power conversion unit 50 and a control unit 73. The power conversion device 100 further has a smoothing capacitor 20 made up of a capacitor element. The power conversion unit 50 and the smoothing capacitor 20 form an inverter circuit, and the control unit 73 controls the inverter circuit.

[0017] The power conversion unit 50 includes a positive-side switching element electrically connected on one side to the positive side of the DC power supply 70, and a negative-side switching element connected in series on one side to the other side of the positive-side switching element and electrically connected on the other side to the negative side of the DC power supply 70. A plurality of arms for one phase are provided, through which AC is output from a connection portion 6a, which is a serially connected portion between the other side of the positive-side switching element and one side of the negative-side switching element, to form multi-phase arms. In this embodiment, the power conversion unit 50 includes three positive-side switching elements 2u, 2v, and 2w and three negative-side switching elements 3u, 3v, and 3w, forming three sets of arms (three sets of series circuits). The positive-side switching element 2u and the negative-side switching element 3u are connected in series, the positive-side switching element 2v and the negative-side switching element 3v are connected in series, and the positive-side switching element 2w and the negative-side switching element 3w are connected in series. Each of the three pairs of arms is connected in parallel to a DC power supply 70 .

[0018] A connection 6a between the positive-side switching element 2u and the negative-side switching element 3u is connected to an input part of a U-phase 60 of the rotating electric machine 72. A connection 6a between the positive-side switching element 2v and the negative-side switching element 3v is connected to an input part of a V-phase 61 of the rotating electric machine 72. A connection 6a between the positive-side switching element 2w and the negative-side switching element 3w is connected to an input part of a W-phase 62 of the rotating electric machine 72. A smoothing capacitor 20 is connected in parallel with each arm. Although FIG. 1 shows a configuration of the power conversion unit 50 having three pairs of arms, the number of arms is not limited to three.

[0019] <Inverter circuit control> The control of the inverter circuit will be explained separately for normal operation and abnormal operation (phase short-circuit operation). During normal operation, multiple switching elements are turned on and off at a predetermined switching frequency in response to commands from the control unit 73. This converts the DC power of the DC power supply 70 into a predetermined AC power. By sequentially turning on and off the switching elements provided for each phase of the inverter circuit, AC powers that are 120 degrees out of phase with each other are supplied to each phase of the rotating electric machine 72. The control unit 73 adjusts the torque and rotation speed of the rotating electric machine 72, which is the load. Furthermore, the rotating electric machine 72 operates as a generator depending on the operating conditions, charging the DC power supply 70 with regenerative power generated by power generation.

[0020] In the event of an abnormality, a phase short-circuit process (phase short-circuit drive) is performed to electrically disconnect the DC power supply 70 and the inverter circuit and stop the AC output from the power conversion unit 50. When stopping the AC output from the power conversion unit 50, the control unit 73 outputs either a phase short-circuit signal (phase short-circuit command) that turns on all of the positive-side switching elements 2u, 2v, and 2w and turns off all of the negative-side switching elements 3u, 3v, and 3w, or a phase short-circuit signal (phase short-circuit command) that turns on all of the negative-side switching elements 3u, 3v, and 3w and turns off all of the positive-side switching elements 2u, 2v, and 2w, to the drivers of the positive-side switching elements 2u, 2v, and 2w and the negative-side switching elements 3u, 3v, and 3w. In this embodiment, a configuration in which all of the positive-side switching elements 2u, 2v, and 2w are turned on and all of the negative-side switching elements 3u, 3v, and 3w are turned off during phase short-circuit drive will be described.

[0021] <Smoothing capacitor 20> The smoothing capacitor 20 is electrically connected to the positive electrode side switching elements 2u, 2v, and 2w and the negative electrode side switching elements 3u, 3v, and 3w via a first wiring 10 and a second wiring 11, which will be described later. The smoothing capacitor 20 has, for example, a capacitor case that houses a capacitor element 20a. Inside the capacitor case, the first wiring 10 and the second wiring 11 are connected to the capacitor element 20a.

[0022] The smoothing capacitor 20 has a function of suppressing ripples in the DC power supply 70. The smoothing capacitor 20 also has a function of lowering the power supply impedance of the inverter circuit and improving the AC current driving capability of the inverter circuit. Furthermore, the smoothing capacitor 20 has a function of absorbing surge voltages.

[0023] <Switching element> The positive-side switching elements 2u, 2v, and 2w and the negative-side switching elements 3u, 3v, and 3w will now be described. Hereinafter, the term "switching elements" refers to both the positive-side switching elements 2u, 2v, and 2w and the negative-side switching elements 3u, 3v, and 3w. Power transistors, which are power semiconductor switching elements capable of operating at high switching frequencies, are often used as switching elements. FIG. 1 illustrates an example in which MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), which are power transistors, are used as switching elements. A freewheel diode (FWD) is connected in parallel to each MOSFET, with the forward direction being from the negative side to the positive side of the DC power supply 70. While MOSFETs are used as switching elements here, the switching elements are not limited to MOSFETs and may be other power transistors, such as insulated gate bipolar transistors (IGBTs) with diodes connected in antiparallel. The switching elements are formed on a semiconductor substrate made of a semiconductor material such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN).

[0024] <Power module 1u, 1v, 1w> In this embodiment, a power module is formed for each phase arm, with a positive-side switching element and a negative-side switching element housed in the same package. Positive-side switching element 2u and negative-side switching element 3u form power module 1u, positive-side switching element 2v and negative-side switching element 3v form power module 1v, and positive-side switching element 2w and negative-side switching element 3w form power module 1w.

[0025] Each of the power modules 1u, 1v, and 1w is formed, for example, by soldering or silver sintering a switching element to a ceramic substrate having copper plates bonded to both sides of the ceramic plate. A plurality of wires extending from the switching elements are connected to a plurality of electrode terminals of each of the power modules 1u, 1v, and 1w. The electrode terminals are terminals for connecting to the outside. The wires are formed of aluminum wire or bus bars punched from copper or copper alloy sheet metal. The electrode terminals are formed, for example, by punching copper or copper alloy sheet metal.

[0026] The multiple electrode terminals will now be described. Each of the multiple power modules 1u, 1v, and 1w has a positive terminal 4 connected to one side of each of the positive-side switching elements 2u, 2v, and 2w and connected to the positive side of a DC power supply, a negative terminal 5 connected to the other side of each of the negative-side switching elements 3u, 3v, and 3w and connected to the negative side of the DC power supply, an external connection terminal 6 connected to the connection portion 6a and from which AC is output, and a control terminal 7 (not shown in FIG. 1) connected to gates that serve as drivers for the positive-side switching elements 2u, 2v, and 2w and the negative-side switching elements 3u, 3v, and 3w and to which an on / off signal is input. The control terminal 7 is connected by soldering or the like to a control unit 73 provided on a circuit board arranged adjacent to the power modules 1u, 1v, and 1w.

[0027] The switching elements, ceramic substrates, wiring, and some of the electrode terminals constituting each of the power modules 1u, 1v, and 1w are integrally molded using, for example, epoxy resin to form the power modules 1u, 1v, and 1w housed in the same package. In this embodiment, as shown in FIG. 2 , the positive terminal 4 and the negative terminal 5 are provided to protrude from the same surface of the package, and the external connection terminal 6 is provided to protrude from the surface opposite to the surface on which the positive terminal 4 and the negative terminal 5 are arranged. The control terminal 7 is provided to protrude from the surface from which the positive terminal 4 and the negative terminal 5 protrude and from the same surface from which the external connection terminal 6 protrudes. In this embodiment, the positive terminal 4 and the negative terminal 5 are arranged on the same surface, and the external connection terminal 6 is arranged on the surface opposite to the positive terminal 4 and the negative terminal 5, but this is not limiting, and the electrode terminals may each protrude from another surface.

[0028] When the positive and negative switching elements are packaged as a pair (2-in-1) in this manner, the number of components in the power conversion device 100 can be reduced compared to when the positive and negative switching elements are packaged individually. Because the number of components is reduced, the productivity of the power conversion device 100 can be improved. Furthermore, when a 2-in-1 structure is adopted, the degree of freedom in arrangement can be improved when increasing the number of phases. While the switching elements are joined to the ceramic substrate by soldering or silver sintering bonding, this is not a limitation. Instead of a ceramic substrate, a frame formed by punching copper or copper sheet metal and an insulating heat dissipation sheet made of silicone or the like can be combined to ensure wiring, heat dissipation, and insulation between the switching elements.

[0029] <First wiring 10, second wiring 11> The first wiring 10 and the second wiring 11 will now be described. The first wiring 10 connects between one side of the multiple positive electrode switching elements 2u, 2v, 2w that are all turned on in the multi-phase arm, or between the other side of the multiple negative electrode switching elements 3u, 3v, 3w that are all turned on in the multi-phase arm. The second wiring 11 connects between one side of the multiple positive electrode switching elements 2u, 2v, 2w that are all turned off in the multi-phase arm, or between the other side of the multiple negative electrode switching elements 3u, 3v, 3w that are all turned off in the multi-phase arm. In this embodiment, power modules 1u, 1v, and 1w are formed, and therefore the first wiring 10 connects between the positive electrode terminals 4 of the multiple power modules 1u, 1v, and 1w or between the negative electrode terminals 5 of the multiple power modules 1u, 1v, and 1w, and the second wiring 11 connects between the positive electrode terminals 4 of the multiple power modules to which the first wiring 10 is not connected or between the negative electrode terminals 5 of the multiple power modules 1u, 1v, and 1w.

[0030] In this embodiment, since all of the positive switching elements 2u, 2v, and 2w are turned on and all of the negative switching elements 3u, 3v, and 3w are turned off during phase short-circuit driving, first wiring 10 connects one side of the multiple positive switching elements 2u, 2v, and 2w, and second wiring 11 connects the other side of the multiple negative switching elements 3u, 3v, and 3w, as shown in Fig. 1. Also, as shown in Fig. 2, first wiring 10 connects the positive terminals 4 of each of the power modules 1u, 1v, and 1w, and second wiring 11 connects the negative terminals 5 of each of the multiple power modules 1u, 1v, and 1w.

[0031] The first wiring 10 and the second wiring 11 are formed by punching and bending from a metal sheet made of copper or a copper alloy. As shown in FIG. 4 , the first wiring 10 has a power module connection portion 16 connected to the positive terminals 4 of the power modules 1u, 1v, and 1w, a smoothing capacitor connection portion 17 connected to the positive side of the capacitor element 20a of the smoothing capacitor 20, and a first power supply terminal 12 connected to the positive side of the DC power supply 70. The first wiring 10 also has a first flat plate portion 14, which is a portion formed in a flat plate shape and connects the power module connection portion 16 and the smoothing capacitor connection portion 17. In FIG. 4 , the portion of the first wiring 10 in the smoothing capacitor 20, excluding the smoothing capacitor connection portion 17, is omitted.

[0032] As shown in Fig. 3, the second wiring 11 has a power module connection portion 16 connected to the negative terminals 5 of the power modules 1u, 1v, and 1w, a smoothing capacitor connection portion 17 connected to the negative side of the capacitor element 20a of the smoothing capacitor 20, and a second power supply terminal 13 connected to the negative side of the DC power supply 70. The second wiring 11 also has a second flat plate portion 15 which is a portion formed in a flat plate shape and connects the power module connection portion 16 and the smoothing capacitor connection portion 17. In Fig. 3, the portion of the second wiring 11 in the smoothing capacitor 20 other than the smoothing capacitor connection portion 17 is omitted.

[0033] The power module connection portion 16 of the first wiring 10 and the positive terminals 4 of the power modules 1u, 1v, and 1w are joined by, for example, welding. The power module connection portion 16 of the second wiring 11 and the negative terminals 5 of the power modules 1u, 1v, and 1w are joined by, for example, welding. The connection between the positive terminals 4 or the negative terminals 5 and the power module connection portion 16 is not limited to welding, and the wirings may be connected by other methods such as soldering, brazing, or screwing. The smoothing capacitor connection portion 17 of the first wiring 10 and the capacitor element 20a of the smoothing capacitor 20 are connected by, for example, soldering. The smoothing capacitor connection portion 17 of the second wiring 11 and the capacitor element 20a of the smoothing capacitor 20 are connected by, for example, soldering. The connection between smoothing capacitor connection portion 17 and capacitor element 20a is not limited to soldering, and each wire and capacitor element 20a may be connected by other methods such as welding, brazing, or screwing.

[0034] In this embodiment, an insulating member 32 is provided that holds the first wiring 10 and the second wiring 11, and the first flat plate portion 14 and the second flat plate portion 15 are stacked with the insulating member 32 interposed therebetween. The first flat plate portion 14 and the second flat plate portion 15 are stacked to form parallel flat plates. The arrangement of the first flat plate portion 14 and the second flat plate portion 15 is not limited to stacking with the insulating member 32 interposed therebetween. A parallel plate configuration may be formed without the insulating member 32 interposed therebetween by ensuring a necessary insulation distance between the first flat plate portion 14 and the second flat plate portion 15. The first flat plate portion 14 is positioned closer to the cooling surface 31 of the cooler 30 than the second flat plate portion 15. The first flat plate portion 14 also has a heat dissipation portion 18 that is thermally connected to the cooling surface 31 of the cooler 30. In this embodiment, the heat dissipation portion 18 is thermally connected to the cooling surface 31 via a heat dissipation member 33. The insulating member 32, the cooler 30, and the heat dissipation member 33 will be described in detail later.

[0035] In the present embodiment, the first wiring 10 and the second wiring 11 are bus bars formed from sheet metal. Because the bus bars are formed by punching and bending a metal sheet, wiring that connects to multiple locations can be made from a single component (metal sheet). This improves the productivity of the power conversion device 100 and reduces the cost of the power conversion device 100. Furthermore, by forming the first wiring 10 and the second wiring 11 from metal sheet instead of copper wire, the first wiring 10 and the second wiring 11 can be arranged to form parallel plates. This allows heat generated in the first wiring 10 during phase short-circuit driving to be dissipated to the second wiring 11 via the insulating member 32.

[0036] Furthermore, by constructing the first wiring 10 and the second wiring 11 from sheet metal rather than copper wire, the first wiring 10 and the second wiring 11 can be arranged as parallel plates, and the proximity effect of the parallel plates can reduce the inductance of the first wiring 10 and the second wiring 11, which connect the smoothing capacitor 20 and the switching elements. Because the inductance of the first wiring 10 and the second wiring 11 is reduced, the surge voltage applied to the switching elements, which is determined by the wiring inductance and the switching speed, can be reduced, improving the reliability of the power conversion device 100 and allowing the use of inexpensive switching elements with low withstand voltages. Furthermore, when the surge voltage is constant, reducing the inductance can increase the switching speed, reducing switching losses and the temperature of the switching elements, thereby improving the reliability of the power conversion device 100 and allowing the use of small, inexpensive switching elements.

[0037] <Insulating member 32> The insulating member 32 provided between the first flat plate portion 14 and the second flat plate portion 15 will be described. The insulating member 32 is made of, for example, polyphenylene sulfide resin. Although not shown, the insulating member 32 has fixing portions for fixing the first wiring 10 and the second wiring 11 to the cooler 30. The insulating member 32 has a function of fixing the first wiring 10 and the second wiring 11 to the cooler 30 by fixing members such as screws.

[0038] Although the insulating member 32 has been described as having a fixing portion, if the first wiring 10 and the second wiring 11 can be held by a member such as a capacitor case that constitutes the smoothing capacitor 20, the insulating member 32 may not have a fixing portion. Furthermore, although the insulating member 32 has been described as holding the first wiring 10 and the second wiring 11, if the first wiring 10 and the second wiring 11 can be held by a member such as a capacitor case that constitutes the smoothing capacitor 20, the insulating member 32 may not hold the first wiring 10 and the second wiring 11, but may be disposed only between the first wiring 10 and the second wiring 11 to insulate the first wiring 10 and the second wiring 11.

[0039] <Heat dissipation member 33> The heat dissipation member 33 provided between the heat dissipation portion 18 of the first flat plate portion 14 and the cooling surface 31 of the cooler 30 will now be described. The heat dissipation member 33 is, for example, a heat dissipation sheet made of silicone. The heat dissipation member 33 is not limited to a heat dissipation sheet made of silicone, and may be grease, hardening grease, or an adhesive. Furthermore, the heat dissipation member 33 may contain a filler or the like to improve the heat dissipation properties of the heat dissipation portion 18 and the insulation between the heat dissipation portion 18 and the cooling surface 31.

[0040] <Cooler 30> The cooler 30 will now be described. One or both of the positive-side switching elements 2u, 2v, 2w and the negative-side switching elements 3u, 3v, 3w are thermally connected to the cooler 30. In this embodiment, power modules 1u, 1v, 1w accommodating the positive-side switching elements 2u, 2v, 2w and the negative-side switching elements 3u, 3v, 3w are provided, and therefore the power modules 1u, 1v, 1w are thermally connected to a cooling surface 31 of the cooler 30. Cooling the power modules 1u, 1v, 1w cools both the positive-side switching elements 2u, 2v, 2w and the negative-side switching elements 3u, 3v, 3w. The configuration is not limited to cooling both the positive-side switching elements 2u, 2v, 2w and the negative-side switching elements 3u, 3v, 3w, and a configuration in which only one of the switching elements is cooled may also be used.

[0041] The cooler 30 is made of, for example, an aluminum alloy by die casting. The material of the cooler 30 is not limited to an aluminum alloy, and may be aluminum, a magnesium alloy, copper, or a copper alloy. When the surface of the ceramic substrate (not shown) of each of the power modules 1u, 1v, and 1w opposite to the surface on which the switching elements are mounted is exposed from the power modules 1u, 1v, and 1w, the opposite surface of the ceramic substrate and the cooling surface 31 are joined via a joining member 34 made of grease or solder. The opposite surface of the ceramic substrate and the cooling surface 31 may also be joined by silver sintering bonding.

[0042] Furthermore, the power conversion device 100 may further include a lid that covers and accommodates the components constituting the power conversion device 100 and other components mounted on the cooling surface 31 of the cooler 30. By providing the lid, the components mounted on the power conversion device 100 can be protected from foreign objects that may enter the power conversion device 100. If the lid is made of metal, the mounted components can be protected from electromagnetic noise. A cooling structure through which a refrigerant flows may be further provided on the side opposite the cooling surface 31 of the cooler 30. The refrigerant is, for example, cooling water. By providing the cooling structure, heat generated from the power modules 1u, 1v, 1w, the first wiring 10, the second wiring 11, and the smoothing capacitor 20 can be efficiently cooled. In this embodiment, the surface to which the power modules 1u, 1v, and 1w are connected and the cooling surface 31 are on the same plane, but this is not limited to this. The cooling surface 31 may be made to protrude from the surface of the cooler 30 to which the power modules 1u, 1v, and 1w are thermally connected, and may be shaped so that the cooling surface 31 is close to the heat dissipation portion 18 of the first flat plate portion 14.

[0043] <Layout of Components of Power Converter 100> The arrangement of components constituting the power conversion device 100 will be described. As shown in FIG. 2, the power conversion device 100 includes a first power supply terminal 12 electrically connected to a first wiring 10 and electrically connecting a DC power supply (not shown) and a power conversion unit 50 via a smoothing capacitor 20, and a second power supply terminal 13 electrically connected to a second wiring 11 and electrically connecting the DC power supply and the power conversion unit 50 via the smoothing capacitor 20. Each of the multiple power modules 1u, 1v, and 1w has a first surface 1a and a second surface 1b facing the first surface 1a on the outer periphery of the package. A positive terminal 4 and a negative terminal 5 protruding from the first surface 1a are provided on the first surface 1a, and an external connection terminal 6 protruding from the second surface 1b is provided on the second surface 1b. A first direction 40 is a direction from the first surface 1a toward the second surface 1b, and a second direction 41 is a direction perpendicular to the first direction 40. The multiple power modules 1u, 1v, 1w are arranged side by side in a second direction 41, and the multiple power modules 1u, 1v, 1w and the smoothing capacitor 20 are arranged side by side in a first direction 40. The first power supply terminal 12 and the second power supply terminal 13 are arranged on the opposite side of the smoothing capacitor 20 from the multiple power modules 1u, 1v, 1w side in the first direction 40. Portions of the first wiring 10 and the second wiring 11 are exposed between the power modules 1u, 1v, 1w and the smoothing capacitor 20.

[0044] In this way, by arranging all of the power modules 1u, 1v, 1w for each arm in the second direction 41 and aligning the positive electrode side terminals 4 and negative electrode side terminals 5 of the power modules 1u, 1v, 1w in one direction, the shapes of the first wiring 10 and the second wiring 11 can be simplified, and the first wiring 10 and the second wiring 11 can be formed by punching and bending a metal plate, so the first wiring 10 and the second wiring 11 can be manufactured inexpensively. Because the first wiring 10 and the second wiring 11 can be manufactured inexpensively, the cost of the power conversion device 100 can be reduced.

[0045] <Current Flow During Normal Operation and Abnormal Operation of Power Conversion Device 100 (During Phase Short-Circuit Operation)> The current flow during normal operation and during an abnormality of the power conversion device 100 will be described. As shown in FIG. 1 , the current path during normal operation is a path through which current flows in the order of the first power supply terminal 12, the first wiring 10, the power modules 1u, 1v, and 1w, the second wiring 11, and the second power supply terminal 13, and AC is output from the external connection terminal 6 to the rotating electric machine 72, which is the load. As shown in FIG. 5 , the current path 51 during phase short-circuit drive, which is the current flow during an abnormality, is configured so that current flows between the first wiring 10, the power modules 1u, 1v, and 1w, and the external connection terminal 6. When an electric vehicle is driven at a constant speed during normal operation, a predetermined current continues to flow through the current path during normal operation. When the electric vehicle is accelerated, a maximum current greater than the predetermined current flows through the current path for a short period of time. During phase short-circuit drive, a current greater than a predetermined current and less than the maximum current during acceleration flows through the current path 51 during phase short-circuit drive for at least a short period of time.

[0046] Thus, during an abnormality, a large current flows through the first wiring 10, which is the ON-side wiring, for a longer period of time than during normal driving, and the first wiring 10 generates more heat than during normal driving. The heat generated by the first wiring 10 is transmitted to peripheral components, such as the smoothing capacitor 20, connected to the first wiring 10, and if the heat resistance temperature of the peripheral components, such as the smoothing capacitor 20, is exceeded, the peripheral components will break down. In the configuration of the present disclosure, the thermal resistance of the first wiring 10, which is the ON-side wiring during phase short-circuit driving, is smaller than the thermal resistance of the second wiring 11. This configuration can suppress heat generation in the first wiring 10, which is the ON-side wiring through which a large current flows for a longer period of time during phase short-circuit driving. Because heat generation in the first wiring 10, which is the ON-side wiring during phase short-circuit driving, is suppressed, thermal damage to components connected to the first wiring 10 can be reduced.

[0047] In the present embodiment, the first wiring 10 has a heat dissipation portion 18 thermally connected to the cooling surface 31 of the cooler 30. With this configuration, the first wiring 10 is thermally connected to the cooling surface 31, so that the thermal resistance of the first wiring 10 can be made smaller than the thermal resistance of the second wiring 11. This allows heat generated in the first wiring 10 during phase short-circuit driving to be efficiently dissipated to the cooler 30. Because the heat generated in the first wiring 10 is efficiently dissipated to the cooler 30, the smoothing capacitor 20 connected to the first wiring 10 can be prevented from exceeding its heat-resistant temperature, thereby extending the life of the smoothing capacitor 20. Since the life of the smoothing capacitor 20 is extended, the life and reliability of the power conversion device 100 can be improved. Furthermore, because the first wiring 10 and the second wiring 11 can be formed from the same material without changing their thicknesses, the power conversion device 100 can be made smaller and less expensive.

[0048] In the present embodiment, the heat dissipation unit 18 is thermally connected to the cooling surface 31 via the heat dissipation member 33. By using the heat dissipation member 33, the heat generated in the first wiring 10 during phase short-circuit driving can be dissipated to the cooler 30 more efficiently.

[0049] Furthermore, in this embodiment, the first flat plate portion 14 is disposed closer to the cooling surface 31 of the cooler 30 than the second flat plate portion 15. With this configuration, the first flat plate portion 14 is cooled by the cooling surface 31, and the thermal resistance of the first wiring 10 can be made smaller than the thermal resistance of the second wiring 11. This allows heat generated in the first wiring 10 during phase short-circuit driving to be efficiently dissipated to the cooler 30. Because the heat generated in the first wiring 10 is efficiently dissipated to the cooler 30, the smoothing capacitor 20 connected to the first wiring 10 can be prevented from exceeding its heat-resistant temperature, thereby extending the life of the smoothing capacitor 20. Since the life of the smoothing capacitor 20 is extended, the life and reliability of the power conversion device 100 can be improved. Furthermore, the first wiring 10 and the second wiring 11 can be formed from the same material without changing their thicknesses, thereby enabling the power conversion device 100 to be reduced in size and cost.

[0050] Furthermore, in this embodiment, an insulating member 32 is provided that holds the first wiring 10 and the second wiring 11, and the first flat plate portion 14 and the second flat plate portion 15 are laminated with the insulating member 32 interposed therebetween. The first flat plate portion 14 and the second flat plate portion 15 are laminated, so that the laminated portions form parallel plates. With this configuration, heat generated in the first wiring 10 during phase short-circuit driving can be dissipated to the second wiring 11 via the insulating member 32. Because the heat generated in the first wiring 10 is dissipated, it is possible to prevent the heat generated in the first wiring 10 from exceeding the heat-resistant temperature of the smoothing capacitor 20. Because the heat-resistant temperature of the smoothing capacitor 20 is prevented from being exceeded, the life of the smoothing capacitor 20 can be extended. Because the life of the smoothing capacitor 20 is extended, it is possible to improve the life and reliability of the power conversion device 100.

[0051] Furthermore, in this embodiment, the smoothing capacitor 20 is electrically connected to the positive-side switching elements 2u, 2v, and 2w and the negative-side switching elements 3u, 3v, and 3w via the first wiring 10 and the second wiring 11. With this configuration, all of the power modules 1u, 1v, and 1w are connected to the smoothing capacitor 20 by the first wiring 10 and the second wiring 11, so there is no need to provide wiring dedicated to the smoothing capacitor 20, and the process, connecting parts, and space required to connect the wiring dedicated to the smoothing capacitor 20 to the first wiring 10 and the second wiring 11 are also unnecessary, so the power conversion device 100 can be made smaller and less expensive.

[0052] In this embodiment, a configuration has been described in which all of the positive side switching elements 2u, 2v, and 2w are turned on and all of the negative side switching elements 3u, 3v, and 3w are turned off during phase short-circuit driving. However, a configuration in which all of the negative side switching elements 3u, 3v, and 3w are turned on and all of the positive side switching elements 2u, 2v, and 2w are turned off during phase short-circuit driving may also be used, in which the second flat plate portion 15 is positioned closer to the cooler 30 than the first flat plate portion 14, a heat dissipation portion 18 is provided on the second flat plate portion 15, and the heat dissipation portion 18 of the second flat plate portion 15 is thermally connected to the cooling surface 31 of the cooler 30 via a heat dissipation member 33.

[0053] <Variation 1> Modifications of the configuration shown in the first embodiment will be described below. First, the configuration of Modification 1 will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of the power conversion device 100 according to Modification 1, cut at the same position as in Fig. 4. In the configuration of the power conversion device 100 shown in Fig. 4, the first wiring 10 is thermally connected to the cooling surface 31 of the cooler 30 via the heat dissipation member 33 at the heat dissipation section 18 provided on the first flat plate portion 14. The configuration for making the thermal resistance of the first wiring 10 smaller than the thermal resistance of the second wiring 11 is not limited to this.

[0054] The configuration for making the thermal resistance of the first wiring 10 smaller than the thermal resistance of the second wiring 11 may be a configuration in which the cross-sectional area of ​​the first wiring 10 in a direction perpendicular to the direction of current flow is larger than the cross-sectional area of ​​the second wiring 11 in a direction perpendicular to the direction of current flow. In FIG. 6, the direction of current flow is the left-right direction in the figure. In the configuration shown in FIG. 6, the thickness of the first wiring 10 is larger than the thickness of the second wiring 11, so that the cross-sectional area of ​​the first wiring 10 is larger than the cross-sectional area of ​​the second wiring 11. With this configuration, the heat dissipation member 33 can be reduced, thereby reducing the cost of the power conversion device 100. Furthermore, the process of providing the heat dissipation member 33 is eliminated, thereby improving the productivity of the power conversion device 100.

[0055] <Variation 2> Next, the configuration of Modification 2 will be described with reference to FIG. 7 . FIG. 7 is a plan view of a power conversion device 100 according to Modification 2. The configuration for making the thermal resistance of the first wiring 10 smaller than the thermal resistance of the second wiring 11 is not limited to the configuration shown in FIG. 4 , in which the first wiring 10 is thermally connected to the cooling surface 31 of the cooler 30 via the heat dissipation member 33. As shown in FIG. 7 , for example, the width of the first flat plate portion 14 of the first wiring 10 in a direction perpendicular to the direction of the current path 51 during phase short-circuit drive (the width in the first direction 40) may be increased relative to the second flat plate portion 15 of the second wiring 11 to reduce the thermal resistance, and the first wiring 10 and the cooler 30 may not be thermally connected via the heat dissipation member 33. Such a configuration can eliminate the need for the heat dissipation member 33, thereby reducing the cost of the power conversion device 100. Furthermore, the elimination of the process for providing the heat dissipation member 33 can improve the productivity of the power conversion device 100.

[0056] <Variation 3> Next, the configuration of Modification 3 will be described with reference to Fig. 8. Fig. 8 is a plan view of a power conversion device 100 according to Modification 3. In the configuration of the power conversion device 100 shown in Fig. 4, the first wiring 10 has a power module connection portion 16, a smoothing capacitor connection portion 17, and a first power supply terminal 12, and is directly connected to the capacitor element 20a of the smoothing capacitor 20 at the smoothing capacitor connection portion 17. In the configuration of the power conversion device 100 shown in Fig. 3, the second wiring 11 has a power module connection portion 16, a smoothing capacitor connection portion 17, and a second power supply terminal 13, and is directly connected to the capacitor element 20a of the smoothing capacitor 20 at the smoothing capacitor connection portion 17. The configuration is not limited to one in which the capacitor element 20a is directly connected to the first wiring 10 and the second wiring 11 by soldering.

[0057] As shown in FIG. 8 , for example, a configuration including a smoothing capacitor wiring 21 may be used. The capacitor element 20a (not shown in FIG. 8 ) is connected to the smoothing capacitor wiring 21 by, for example, soldering. The smoothing capacitor wiring 21 is connected to the first wiring 10 and the second wiring 11 at smoothing capacitor connection portions 17 of the first wiring 10 and the second wiring 11. The first power supply terminal 12 and the second power supply terminal 13 are provided on the smoothing capacitor wiring 21. By providing the smoothing capacitor 20 and the smoothing capacitor wiring 21 as separate components from the first wiring 10 and the second wiring 11, the smoothing capacitor 20 and the smoothing capacitor wiring 21 can be used without changing the shape of the smoothing capacitor 20 and the smoothing capacitor wiring 21 when the connection positions of the power modules 1u, 1v, and 1w and the first wiring 10 and the second wiring 11 are changed, thereby reducing the manufacturing cost of the smoothing capacitor 20 and the smoothing capacitor wiring 21. The reduced manufacturing cost of the smoothing capacitor 20 and the smoothing capacitor wiring 21 allows the cost of the power conversion device 100 to be reduced.

[0058] <Variation 4> Next, the configuration of Modification 4 will be described with reference to FIG. 9 . FIG. 9 is a cross-sectional view of a power converter 100 according to Modification 4, taken at the same position as FIG. 4 . The configuration for making the thermal resistance of the first wiring 10 smaller than the thermal resistance of the second wiring 11 is not limited to the configuration shown in FIG. 4 , in which the first wiring 10 is thermally connected to the cooling surface 31 of the cooler 30 via the heat dissipation member 33. Instead of directly thermally connecting the heat dissipation unit 18 to the heat dissipation member 33, as shown in FIG. 9 , the power converter 100 may include an insulating member 32 that holds the first wiring 10 and the second wiring 11, and the heat dissipation unit 18 may be covered by the insulating member 32. The heat dissipation unit 18 covered by the insulating member 32 is thermally connected to the cooling surface 31 of the cooler 30 via the insulating member 32 and the heat dissipation member 33. With this configuration, the insulating member 32 can improve insulation between the first wiring 10 and the cooler 30. Since the insulation between the first wiring 10 and the cooler 30 is improved, the insulation of the power conversion device 100 can be improved.

[0059] <Variation 5> Next, the configuration of Modification 5 will be described with reference to FIG. 10. FIG. 10 is a plan view of the power conversion device 100 according to Modification 5. In the configuration of the power conversion device 100 shown in FIG. 2, one power module 1u, 1v, 1w is provided for each of three sets of arms. The configuration is not limited to one power module 1u, 1v, 1w provided for each set of arms. As shown in FIG. 10, a configuration in which two power modules 1u, 1v, 1w are provided in parallel for each set of arms is also acceptable. With this configuration, the output of the power conversion device 100 can be increased without changing the configuration of each of the power modules 1u, 1v, 1w.

[0060] <Variation 6> Next, the configuration of Modification 6 will be described with reference to FIG. 11. FIG. 11 is a plan view of the power conversion device 100 according to Modification 6. In the configuration of the power conversion device 100 shown in FIG. 2, one power module 1u, 1v, 1w is provided for each of the three arms. The configuration is not limited to one power module 1u, 1v, 1w provided for each arm. In the configuration of the power conversion device 100 according to Modification 6, a power module is formed in which all of the positive-side switching elements and negative-side switching elements provided in each of the multiple arms are housed in the same package. This power module is referred to as an integrated module 8. In the configuration example shown in FIG. 11, the power modules of the three arms are housed in the same package.

[0061] The integrated module 8 has a plurality of positive terminals 4 connected to one side of the positive switching elements for each phase arm and connected to the positive side of a DC power supply (not shown), a plurality of negative terminals 5 connected to the other side of the negative switching elements for each phase arm and connected to the negative side of the DC power supply, a plurality of external connection terminals 6 connected to the connection portions 6a for each phase arm and from which AC is output, and a control terminal 7 connected to a control unit 73. First wiring 10 connects between each of the plurality of positive terminals 4 or between each of the plurality of negative terminals 5, and second wiring 11 connects between each of the plurality of positive terminals 4 or between each of the plurality of negative terminals 5 to which the first wiring 10 is not connected.

[0062] By forming the integrated module 8 in which all of the multiple arms are housed in the same package in this way, the number of parts in the power module can be reduced, and the manufacturing cost of the power module can be reduced. Since the manufacturing cost of the power module is reduced, the cost of the power conversion device 100 can be reduced.

[0063] <Variation 7> Next, the configuration of Modification 7 will be described with reference to FIG. 12. FIG. 12 is a plan view of a power conversion device 100 according to Modification 7. In the configuration of the power conversion device 100 shown in FIG. 2, the first power supply terminal 12 and the second power supply terminal 13 are arranged in the first direction 40 on the side of the smoothing capacitor 20 opposite to the side of the multiple power modules 1u, 1v, and 1w. The arrangement of the first power supply terminal 12 and the second power supply terminal 13 is not limited thereto. In the configuration of the power conversion device 100 of Modification 7, the first power supply terminal 12 and the second power supply terminal 13 are arranged in the second direction 41 adjacent to the smoothing capacitor 20 or the multiple power modules. In the configuration example shown in FIG. 12, the first power supply terminal 12 and the second power supply terminal 13 are arranged adjacent to the smoothing capacitor 20.

[0064] This configuration can improve the degree of freedom in arranging the first power supply terminal 12 and the second power supply terminal 13 of the power conversion device 100. Since the degree of freedom in arranging the first power supply terminal 12 and the second power supply terminal 13 is improved, the degree of freedom in arranging the power conversion device 100 and the DC power supply can be improved.

[0065] As described above, the power conversion device 100 according to the first embodiment includes the power conversion unit 50 having a positive-side switching element and a negative-side switching element, and a plurality of arms for one phase through which AC is output from the connection between both elements, forming a plurality of arms for multiple phases; the control unit 73 that, when stopping the AC, outputs either a phase short-circuit signal that turns on all of the positive-side switching elements and turns off all of the negative-side switching elements, or a phase short-circuit signal that turns on all of the negative-side switching elements and turns off all of the positive-side switching elements; first wiring 10 connecting the plurality of positive-side switching elements or negative-side switching elements that are all turned on; and second wiring 11 connecting the plurality of positive-side switching elements or negative-side switching elements that are all turned off. Since the thermal resistance of the first wiring 10, which is the ON-side wiring during phase short-circuit driving, is smaller than the thermal resistance of the second wiring 11, it is possible to suppress heat generation in the first wiring 10, which is the ON-side wiring through which a large current flows for a long time during phase short-circuit driving. Since heat generation in the first wiring 10, which is the ON-side wiring during phase short-circuit driving, is suppressed, heat damage to components connected to the first wiring 10 can be reduced.

[0066] For each phase arm, a power module is formed in which a positive-side switching element and a negative-side switching element are housed in the same package, and each of the multiple power modules has a positive-side terminal 4 connected to one side of the positive-side switching element and connected to the positive side of the DC power supply, a negative-side terminal 5 connected to the other side of the negative-side switching element and connected to the negative side of the DC power supply, and an external connection terminal 6 connected to the connection part 6a and outputting AC. By packaging the positive-side switching element and the negative-side switching element as a pair (2-in-1), the number of parts in the power conversion device 100 can be reduced compared to when the positive-side switching element and the negative-side switching element are packaged individually. Because the number of parts is reduced, the productivity of the power conversion device 100 can be improved.

[0067] When a power module is formed in which all of the positive and negative switching elements of each of the multiple arms are housed in the same package, and the power module has multiple positive terminals 4 connected to one side of the positive switching elements of each phase arm and connected to the positive side of the DC power supply, multiple negative terminals 5 connected to the other side of the negative switching elements of each phase arm and connected to the negative side of the DC power supply, and multiple external connection terminals 6 connected to the connection parts 6a of each phase arm and from which AC is output, the number of parts of the power module can be reduced, and the manufacturing cost of the power module can be reduced. Since the manufacturing cost of the power module is reduced, the cost of the power conversion device 100 can be reduced.

[0068] When the cross-sectional area of ​​the first wiring 10 in the direction perpendicular to the current flow direction is larger than the cross-sectional area of ​​the second wiring 11 in the direction perpendicular to the current flow direction, the heat dissipation member 33 can be reduced, thereby reducing the cost of the power conversion device 100. Furthermore, since the process of providing the heat dissipation member 33 is eliminated, the productivity of the power conversion device 100 can be improved.

[0069] When the first wiring 10 and the second wiring 11 are bus bars formed from sheet metal, the bus bars are formed by punching and bending the sheet metal, and therefore wiring that connects to multiple locations can be made from a single component (sheet metal), thereby improving the productivity of the power conversion device 100 and reducing the cost of the power conversion device 100. Furthermore, by forming the first wiring 10 and the second wiring 11 from sheet metal instead of copper wire, the first wiring 10 and the second wiring 11 can be arranged to form parallel plates, and therefore heat generated in the first wiring 10 during phase short-circuit driving can be dissipated to the second wiring 11 via the insulating member 32.

[0070] When the first wiring 10 has a heat dissipation portion 18 thermally connected to the cooling surface 31 of the cooler 30, the first wiring 10 is thermally connected to the cooling surface 31, so that the thermal resistance of the first wiring 10 can be made smaller than the thermal resistance of the second wiring 11. This allows the heat generated in the first wiring 10 during phase short-circuit driving to be efficiently dissipated to the cooler 30. Since the heat generated in the first wiring 10 is efficiently dissipated to the cooler 30, the smoothing capacitor 20 connected to the first wiring 10 can be prevented from exceeding its heat-resistant temperature, thereby extending the life of the smoothing capacitor 20. Since the life of the smoothing capacitor 20 is extended, the life and reliability of the power conversion device 100 can be improved.

[0071] When the power conversion device 100 includes the insulating member 32 that holds the first wiring 10 and the second wiring 11, and the heat dissipation unit 18 is covered by the insulating member 32, the heat dissipation unit 18 covered by the insulating member 32 is thermally connected to the cooling surface 31 of the cooler 30 via the insulating member 32 and the heat dissipation member 33, and therefore the insulating member 32 can improve the insulation between the first wiring 10 and the cooler 30. Since the insulation between the first wiring 10 and the cooler 30 is improved, the insulation of the power conversion device 100 can be improved.

[0072] When the power conversion device 100 includes an insulating member 32 that holds the first wiring 10 and the second wiring 11, and the first flat plate portion 14 and the second flat plate portion 15 are stacked with the insulating member 32 interposed therebetween, heat generated in the first wiring 10 during phase short-circuit driving can be dissipated to the second wiring 11 via the insulating member 32. Because the heat generated in the first wiring 10 is dissipated, it is possible to prevent the heat generated in the first wiring 10 from exceeding the heat-resistant temperature of the smoothing capacitor 20. Because the heat-resistant temperature of the smoothing capacitor 20 is prevented from being exceeded, it is possible to extend the life of the smoothing capacitor 20. Because the life of the smoothing capacitor 20 is extended, it is possible to improve the life and reliability of the power conversion device 100.

[0073] When the first flat plate portion 14 is disposed closer to the cooling surface 31 of the cooler 30 than the second flat plate portion 15, the first flat plate portion 14 is cooled by the cooling surface 31, and the thermal resistance of the first wiring 10 can be made smaller than the thermal resistance of the second wiring 11, so that heat generated in the first wiring 10 during phase short-circuit driving can be efficiently dissipated to the cooler 30. Because the heat generated in the first wiring 10 is efficiently dissipated to the cooler 30, the smoothing capacitor 20 connected to the first wiring 10 can be prevented from exceeding its heat-resistant temperature, and the life of the smoothing capacitor 20 can be extended. Because the life of the smoothing capacitor 20 is extended, the life and reliability of the power conversion device 100 can be improved.

[0074] When the power conversion device 100 is provided with a smoothing capacitor 20 electrically connected to the positive side switching elements 2u, 2v, 2w and the negative side switching elements 3u, 3v, 3w via the first wiring 10 and the second wiring 11, all of the power modules 1u, 1v, 1w and the smoothing capacitor 20 are connected by the first wiring 10 and the second wiring 11, so there is no need to provide wiring dedicated to the smoothing capacitor 20, and the process, connecting parts, and space for connecting the wiring dedicated to the smoothing capacitor 20 to the first wiring 10 and the second wiring 11 are also not required, so the power conversion device 100 can be made smaller and less expensive.

[0075] The power conversion device 100 includes a first power supply terminal 12 electrically connected to a first wiring 10 and electrically connecting a DC power supply and a power conversion unit 50 via a smoothing capacitor 20, and a second power supply terminal 13 electrically connected to a second wiring 11 and electrically connecting the DC power supply and the power conversion unit 50 via the smoothing capacitor 20, and each of the plurality of power modules 1u, 1v, and 1w has a first surface 1a and a second surface 1b facing the first surface 1a, a positive electrode side terminal 4 and a negative electrode side terminal 5 are provided on the first surface 1a, and an external connection terminal 6 is provided on the second surface 1b, and each of the plurality of power modules 1u, 1v, and 1w is arranged side by side in a second direction 41, and the plurality of power modules 1u, 1v, and 1w are arranged side by side in a second direction 41. , 1w and the smoothing capacitor 20 are arranged side by side in a first direction 40, and the first power supply terminal 12 and the second power supply terminal 13 are arranged in the first direction 40 on the opposite side of the smoothing capacitor 20 from the side where the multiple power modules 1u, 1v, and 1w are located. By arranging all of the power modules 1u, 1v, and 1w for each arm in a second direction 41 and aligning the positive and negative terminals 4 and 5 of the power modules 1u, 1v, and 1w in a single direction, the shapes of the first wiring 10 and the second wiring 11 can be simplified. Therefore, the first wiring 10 and the second wiring 11 can be formed by punching and bending a metal plate, and the first wiring 10 and the second wiring 11 can be manufactured inexpensively. Because the first wiring 10 and the second wiring 11 can be manufactured inexpensively, the cost of the power conversion device 100 can be reduced.

[0076] When the first power supply terminal 12 and the second power supply terminal 13 are arranged adjacent to the smoothing capacitor 20 or a plurality of power modules in the second direction 41, it is possible to improve the degree of freedom in arranging the first power supply terminal 12 and the second power supply terminal 13 of the power conversion device 100. Because the degree of freedom in arranging the first power supply terminal 12 and the second power supply terminal 13 is improved, it is possible to improve the degree of freedom in arranging the power conversion device 100 and the DC power supply.

[0077] While the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not exemplified are conceivable within the scope of the technology disclosed in this specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment.

[0078] Various aspects of the present disclosure are summarized below as appendices.

[0079] (Appendix 1) a power conversion unit having a positive-side switching element electrically connected on one side to the positive-side side of a DC power supply, and a negative-side switching element connected in series on one side to the other side of the positive-side switching element and electrically connected on the other side to the negative-side side of the DC power supply, wherein a plurality of arms for one phase are provided through which AC is output from a connection portion that is a portion connected in series between the other side of the positive-side switching element and one side of the negative-side switching element, and in which arms for multiple phases are formed; a control unit that outputs, when stopping the AC output from the power conversion unit, either a phase short-circuit signal that turns on all of the positive electrode side switching elements and turns off all of the negative electrode side switching elements, or a phase short-circuit signal that turns on all of the negative electrode side switching elements and turns off all of the positive electrode side switching elements, to a drive unit for the positive electrode side switching elements and the negative electrode side switching elements; a first wiring that connects one side of the plurality of positive electrode side switching elements that are all turned on or the other side of the plurality of negative electrode side switching elements that are all turned on in the arms of the plurality of phases; a second wiring that connects one side of the plurality of positive electrode side switching elements that are all turned off or the other side of the plurality of negative electrode side switching elements that are all turned off in the arms of the plurality of phases, A power conversion device in which the thermal resistance of the first wiring is smaller than the thermal resistance of the second wiring. (Appendix 2) a power module is formed for each arm of each phase, in which the positive electrode side switching element and the negative electrode side switching element are housed in the same package; each of the plurality of power modules has a positive terminal connected to one side of the positive switching element and connected to the positive side of a DC power supply, a negative terminal connected to the other side of the negative switching element and connected to the negative side of the DC power supply, and an external connection terminal connected to the connection portion and from which AC is output; the first wiring connects the positive electrode terminals of the plurality of power modules or the negative electrode terminals of the plurality of power modules, 2. The power conversion device according to claim 1, wherein the second wiring connects between the positive electrode side terminals of the power modules or between the negative electrode side terminals of the power modules to which the first wiring is not connected. (Appendix 3) a power module is formed in which all of the positive electrode side switching elements and the negative electrode side switching elements included in each of the plurality of arms are housed in the same package; the power module has: a plurality of positive-side terminals connected to one side of the positive-side switching elements for each arm of each phase and connected to the positive side of a DC power supply; a plurality of negative-side terminals connected to the other side of the negative-side switching elements for each arm of each phase and connected to the negative side of the DC power supply; and a plurality of external connection terminals connected to the connection portion for each arm of each phase and from which AC is output; the first wiring connects between the plurality of positive electrode terminals or between the plurality of negative electrode terminals, 2. The power conversion device according to claim 1, wherein the second wiring connects between each of the plurality of positive electrode side terminals or each of the plurality of negative electrode side terminals to which the first wiring is not connected. (Appendix 4) 4. The power conversion device according to claim 1, wherein the cross-sectional area of ​​the first wiring in a direction perpendicular to the direction in which the current flows is larger than the cross-sectional area of ​​the second wiring in a direction perpendicular to the direction in which the current flows. (Appendix 5) 5. The power conversion device according to claim 1, wherein the first wiring and the second wiring are bus bars formed from sheet metal. (Appendix 6) The positive-side switching element and / or the negative-side switching element further include a cooler thermally connected thereto, 6. The power conversion device according to claim 1, wherein the first wiring has a heat dissipation part thermally connected to a cooling surface of the cooler. (Appendix 7) an insulating member that holds the first wiring and the second wiring; 7. The power conversion device according to claim 6, wherein the heat dissipation portion is covered with the insulating member. (Appendix 8) an insulating member that holds the first wiring and the second wiring; the first wiring has a first flat plate portion which is a portion formed in a flat plate shape, and the second wiring has a second flat plate portion which is a portion formed in a flat plate shape, 7. The power converter according to claim 1, wherein the first flat plate portion and the second flat plate portion are stacked with the insulating member interposed therebetween. (Appendix 9) The positive-side switching element and / or the negative-side switching element further include a cooler thermally connected thereto, 9. The power conversion device according to claim 8, wherein the first flat plate portion is disposed closer to the cooling surface of the cooler than the second flat plate portion. (Appendix 10) 10. The power conversion device according to any one of claims 1 to 9, further comprising a capacitor element electrically connected to the positive electrode side switching element and the negative electrode side switching element via the first wiring and the second wiring. (Appendix 11) a capacitor element electrically connected to the positive electrode side switching element and the negative electrode side switching element via the first wiring and the second wiring; a first power supply terminal electrically connected to the first wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element; a second power supply terminal electrically connected to the second wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element, Each of the plurality of power modules has a first surface and a second surface facing the first surface at an outer periphery of the package, The positive electrode side terminal and the negative electrode side terminal are provided on the first surface, and protrude from the first surface, the external connection terminal is provided on the second surface and protrudes from the second surface; a direction from the first surface toward the second surface is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction; the plurality of power modules are arranged side by side in the second direction, The plurality of power modules and the capacitor elements are arranged side by side in the first direction, 3. The power conversion device according to claim 2, wherein the first power supply terminal and the second power supply terminal are arranged on a side of the capacitor element opposite to a side of the power modules in the first direction. (Appendix 12) a capacitor element electrically connected to the positive electrode side switching element and the negative electrode side switching element via the first wiring and the second wiring; a first power supply terminal electrically connected to the first wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element; a second power supply terminal electrically connected to the second wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element, Each of the plurality of power modules has a first surface and a second surface facing the first surface at an outer periphery of the package, The positive electrode side terminal and the negative electrode side terminal are provided on the first surface, and protrude from the first surface, the external connection terminal is provided on the second surface and protrudes from the second surface; a direction from the first surface toward the second surface is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction; the plurality of power modules are arranged side by side in the second direction, The plurality of power modules and the capacitor elements are arranged side by side in the first direction, 3. The power conversion device according to claim 2, wherein the first power supply terminal and the second power supply terminal are arranged adjacent to the capacitor element or the plurality of power modules in the second direction. [Explanation of symbols]

[0080] 1u, 1v, 1w power module, 1a first surface, 1b second surface, 2u, 2v, 2w positive side switching elements, 3u, 3v, 3w negative side switching elements, 4 positive side terminal, 5 negative side terminal, 6 external connection terminal, 6a connection portion, 7 control terminal, 8 integrated module, 10 first wiring, 11 second wiring, 12 first power supply terminal, 13 second power supply terminal, 14 first flat plate portion, 15 second flat plate portion, 16 power module connection portion, 17 smoothing capacitor connection portion, 18 heat dissipation portion, 20 smoothing capacitor, 20a capacitor element, 21 smoothing capacitor wiring, 30 cooler, 31 cooling surface, 32 insulating member, 33 heat dissipation member, 34 joining member, 40 first direction, 41 second direction, 50 power conversion portion, 51 current path during phase short circuit drive, 60 U phase, 61 V phase, 62 W phase, 70 DC power supply, 72 rotating electric machine, 73 control unit, 74 auxiliary machine, 100 power conversion device, 101 drive system of electric vehicle

Claims

1. a power conversion unit having a positive-side switching element electrically connected on one side to the positive-side side of a DC power supply, and a negative-side switching element connected in series on one side to the other side of the positive-side switching element and electrically connected on the other side to the negative-side side of the DC power supply, wherein a plurality of arms for one phase are provided through which AC is output from a connection portion that is a portion connected in series between the other side of the positive-side switching element and one side of the negative-side switching element, and in which arms for multiple phases are formed; a control unit that outputs, when stopping the AC output from the power conversion unit, either a phase short-circuit signal that turns on all of the positive electrode side switching elements and turns off all of the negative electrode side switching elements, or a phase short-circuit signal that turns on all of the negative electrode side switching elements and turns off all of the positive electrode side switching elements, to a drive unit for the positive electrode side switching elements and the negative electrode side switching elements; a first wiring that connects one side of the plurality of positive electrode side switching elements that are all turned on or the other side of the plurality of negative electrode side switching elements that are all turned on in the arms of the plurality of phases; a second wiring that connects one side of the plurality of positive electrode side switching elements that are all turned off or the other side of the plurality of negative electrode side switching elements that are all turned off in the arms of the plurality of phases, A power conversion device in which the thermal resistance of the first wiring is smaller than the thermal resistance of the second wiring.

2. a power module is formed for each arm of each phase, in which the positive electrode side switching element and the negative electrode side switching element are housed in the same package; each of the plurality of power modules has a positive terminal connected to one side of the positive switching element and connected to the positive side of a DC power supply, a negative terminal connected to the other side of the negative switching element and connected to the negative side of the DC power supply, and an external connection terminal connected to the connection portion and from which AC is output; the first wiring connects the positive electrode terminals of the plurality of power modules or the negative electrode terminals of the plurality of power modules, 2. The power conversion device according to claim 1, wherein the second wiring connects between the positive electrode side terminals of the plurality of power modules or between the negative electrode side terminals of the plurality of power modules to which the first wiring is not connected.

3. a power module is formed in which all of the positive electrode side switching elements and the negative electrode side switching elements included in each of the plurality of arms are housed in the same package; the power module has: a plurality of positive-side terminals connected to one side of the positive-side switching elements for each arm of each phase and connected to the positive side of a DC power supply; a plurality of negative-side terminals connected to the other side of the negative-side switching elements for each arm of each phase and connected to the negative side of the DC power supply; and a plurality of external connection terminals connected to the connection portion for each arm of each phase and from which AC is output; the first wiring connects between the plurality of positive electrode terminals or between the plurality of negative electrode terminals, The power conversion device according to claim 1 , wherein the second wiring connects between each of the plurality of positive electrode side terminals or each of the plurality of negative electrode side terminals to which the first wiring is not connected.

4. The power conversion device according to claim 1 , wherein a cross-sectional area of ​​the first wiring in a direction perpendicular to a direction in which the current flows is larger than a cross-sectional area of ​​the second wiring in a direction perpendicular to the direction in which the current flows.

5. The power conversion device according to claim 1 , wherein the first wiring and the second wiring are bus bars formed from sheet metal.

6. The positive-side switching element and / or the negative-side switching element further include a cooler thermally connected thereto, The power conversion device according to claim 1 , wherein the first wiring has a heat dissipation portion thermally connected to a cooling surface of the cooler.

7. an insulating member that holds the first wiring and the second wiring; The power conversion device according to claim 6 , wherein the heat dissipation portion is covered with the insulating member.

8. an insulating member that holds the first wiring and the second wiring; the first wiring has a first flat plate portion which is a portion formed in a flat plate shape, and the second wiring has a second flat plate portion which is a portion formed in a flat plate shape, The power conversion device according to claim 1 , wherein the first flat plate portion and the second flat plate portion are stacked with the insulating member interposed therebetween.

9. The positive-side switching element and / or the negative-side switching element further include a cooler thermally connected thereto, The power conversion device according to claim 8 , wherein the first flat plate portion is disposed closer to the cooling surface of the cooler than the second flat plate portion.

10. The power conversion device according to any one of claims 1 to 3, further comprising a capacitor element electrically connected to the positive electrode side switching element and the negative electrode side switching element via the first wiring and the second wiring.

11. a capacitor element electrically connected to the positive electrode side switching element and the negative electrode side switching element via the first wiring and the second wiring; a first power supply terminal electrically connected to the first wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element; a second power supply terminal electrically connected to the second wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element, Each of the plurality of power modules has a first surface and a second surface facing the first surface at an outer periphery of the package, The positive electrode side terminal and the negative electrode side terminal are provided on the first surface, and protrude from the first surface, the external connection terminal is provided on the second surface and protrudes from the second surface; a direction from the first surface toward the second surface is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction; the plurality of power modules are arranged side by side in the second direction, The plurality of power modules and the capacitor elements are arranged side by side in the first direction, The power conversion device according to claim 2 , wherein the first power supply terminal and the second power supply terminal are arranged on a side of the capacitor element opposite to a side of the plurality of power modules in the first direction.

12. a capacitor element electrically connected to the positive electrode side switching element and the negative electrode side switching element via the first wiring and the second wiring; a first power supply terminal electrically connected to the first wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element; a second power supply terminal electrically connected to the second wiring and electrically connecting a DC power supply and the power conversion unit via the capacitor element, Each of the plurality of power modules has a first surface and a second surface facing the first surface at an outer periphery of the package, The positive electrode side terminal and the negative electrode side terminal are provided on the first surface, and protrude from the first surface, the external connection terminal is provided on the second surface and protrudes from the second surface; a direction from the first surface toward the second surface is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction; the plurality of power modules are arranged side by side in the second direction, The plurality of power modules and the capacitor elements are arranged side by side in the first direction, The power conversion device according to claim 2 , wherein the first power supply terminal and the second power supply terminal are arranged adjacent to the capacitor element or the plurality of power modules in the second direction.

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