Power conversion device

Abstract

The present invention comprises: a relay bus bar that passes through the inside of a second power module and is connected to an external terminal of a first power module, and that electrically connects a DC power-supply terminal to the first power module and the second power module; and a capacitor module that is connected to the relay bus bar in parallel with the first power module.

Description

Power Conversion Device

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

[0002] For example, Patent Document 1 discloses a power conversion device that includes a capacitor module and a power module. The power conversion device disclosed in Patent Document 1 is mounted on a vehicle and disposed between a battery and a motor. This power conversion device has an inverter circuit that converts DC power to AC power and AC power to DC power.

[0003] Patent No. 4859443

[0004] A power conversion device includes a bus bar that carries a large current between a battery and a motor. For example, the power conversion device includes a relay bus bar that directly connects a DC power supply terminal to which a battery is connected and a power module that forms an inverter circuit. Such a relay bus bar may be provided so as to pass through the inside of a capacitor module at a location along the way from the DC power supply terminal to the power module. The relay bus bar generates heat when a current flows through it. Therefore, if the relay bus bar passes through the inside of the capacitor module, the temperature of the capacitor module will rise. As a result, it may become necessary to incorporate a cooler into the capacitor module, which may result in an increase in the size of the capacitor module.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to reduce the size of a capacitor module.

[0006] The present invention employs the following configuration as a means for solving the above problems.

[0007] One aspect of the present invention employs a configuration including a DC power supply terminal connected to a battery, a first power module that performs power conversion, a second power module that performs power conversion and is separate from the first power module, a relay bus bar that passes through the inside of the second power module to be connected to an external terminal of the first power module and that electrically connects the DC power supply terminal to the first power module and the second power module, and a capacitor module that is connected in parallel to the first power module with respect to the relay bus bar.

[0008] According to the present invention, the relay bus bar connecting the DC power supply terminal and the external terminal of the first power module passes through the second power module and is connected to the first power module without passing through the capacitor module, which allows the capacitor module to be made smaller.

[0009] FIG. 1 is an exploded perspective view schematically showing the general configuration of a power conversion device according to a first embodiment of the present invention. FIG. 2 is a circuit diagram showing the general electrical configuration of the power conversion device according to the first embodiment of the present invention. FIG. 3 is a schematic plan view of a main power module included in the power conversion device according to the first embodiment of the present invention. FIG. 4 is a schematic plan view of a sub-power module and a relay bus bar module included in the power conversion device according to the first embodiment of the present invention. FIG. 5 is a perspective view of the relay bus bar module included in the power conversion device according to the first embodiment of the present invention. FIG. 6 is a schematic plan view of the main power module, the sub-power module, and the relay bus bar module included in the power conversion device according to the first embodiment of the present invention. FIG. 7 is a schematic diagram showing the positional relationship between external terminals, power module connection terminals, and capacitor module terminals included in the power conversion device according to the first embodiment of the present invention. FIG. 8 is a schematic plan view of the sub-power module and the relay bus bar module included in the power conversion device according to a second embodiment of the present invention.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power conversion device according to the present invention will be described below with reference to the drawings.

[0011] (First Embodiment) Fig. 1 is an exploded perspective view schematically showing the overall configuration of a power conversion device 1 according to one embodiment of the present invention. The power conversion device 1 according to this embodiment is mounted on a vehicle such as an electric automobile, and is provided between a motor (see Fig. 2) and a battery B (see Fig. 2). The power conversion device 1 according to this embodiment performs power conversion between the motor and the battery B. As shown in Fig. 1, the power conversion device 1 according to this embodiment includes an inverter case 2, a main intelligent power module 3, a cooler 4, a sub intelligent power module 5, a capacitor module 6, a relay bus bar module 7, and a DC power supply terminal 8. Note that the power conversion device 1 may also include other components, such as a DC-DC converter and a reactor (not shown).

[0012] The inverter case 2 is a case that houses the main intelligent power module 3, the cooler 4, the sub intelligent power module 5, the capacitor module 6, the relay bus bar module 7, the DC power terminals 8, etc., and includes a central case 2a and a case cover 2b. The central case 2a and the case cover 2b are formed as separate parts that can be detached from each other. In FIG. 1, the case cover 2b is shown separated from the central case 2a above. However, the installation posture of the power conversion device 1 is not particularly limited. In other words, the power conversion device 1 may be mounted on a vehicle so that the case cover 2b is located to the side of the central case 2a.

[0013] The central case 2a has a bottom wall to which the main intelligent power module 3 and the cooler 4 are fixed. The central case 2a also has side walls that surround the main intelligent power module 3, the cooler 4, the sub intelligent power module 5, the capacitor module 6, the relay bus bar module 7, etc. In other words, the central case 2a is formed in the shape of a container that is open on the case cover 2b side. Such a bottom wall is provided with a water channel as necessary, and is formed to be able to guide the coolant that cools the main intelligent power module 3.

[0014] The case cover 2b is fixed to the central case 2a and covers the main intelligent power module 3, the cooler 4 (cooling unit), the sub intelligent power module 5, the capacitor module 6, the relay bus bar module 7, and the DC power terminal 8. In other words, the main intelligent power module 3 and the capacitor module 6 are exposed when the case cover 2b is detached from the central case 2a.

[0015] The inverter case 2 is fixed to, for example, a housing (not shown) that covers the motor or a gear case that houses a gear that transmits power generated by the motor to the outside. In such a case, for example, the central case 2 a is fastened to the motor housing or the gear case using bolts (not shown) or the like.

[0016] The main intelligent power module 3 includes a main power module 3a (first power module) and a main board unit 3b. The main power module 3a is a module provided with a plurality of power devices D, which will be described later. The configuration of the main power module 3a will be described later.

[0017] The main board unit 3b is stacked on the main power module 3a. This main board unit 3b includes, for example, a gate driver board and an ECU (Electronic Control Unit) board. The gate driver board is a board provided with a gate driver that generates a drive signal for the inverter formed by the main power module 3a. The ECU board is a board provided with an ECU that controls the gate driver board.

[0018] The cooler 4 is disposed adjacent to the main intelligent power module 3 and below the sub intelligent power module 5. The cooler 4 cools the sub intelligent power module 5 (i.e., a sub power module 5a described later). The cooler 4 absorbs heat from the sub intelligent power module 5 into a coolant supplied from the outside and discharges the heat-absorbing coolant to the outside.

[0019] The sub intelligent power module 5 includes a sub power module 5a (second power module) and a sub substrate unit 5b. The sub power module 5a is a module provided with a plurality of power devices D (described later) and is provided separately from the main power module 3a. The configuration of the sub power module 5a will be described later.

[0020] The sub-board unit 5b is stacked on the sub-power module 5a. This sub-board unit 5b includes, for example, a gate driver board and an ECU board. The gate driver board is a board provided with a gate driver that generates a drive signal for the inverter formed by the sub-power module 5a. The ECU board is a board provided with an ECU that controls the gate driver board.

[0021] The capacitor module 6 is a module that includes a capacitor C (described later) inside a case. The capacitor module 6 is disposed above the sub-intelligent power module 5. However, as described above, the installation posture of the power conversion device 1 is not limited. In other words, the capacitor module 6 is disposed on the opposite side of the sub-intelligent power module 5 (i.e., the sub-power module 5a) from the cooler 4.

[0022] The capacitor module 6 has terminals (capacitor module terminals 6a) exposed to the outside of the case. In this embodiment, the capacitor module 6 has three capacitor module terminals 6a connected to one terminal of the capacitor C and three capacitor module terminals 6a connected to the other terminal of the capacitor C. That is, in this embodiment, the capacitor module 6 has six capacitor module terminals 6a. These capacitor module terminals 6a are arranged on the main intelligent power module 3 side as shown in FIG. 1 .

[0023] The relay busbar module 7 is a plate-shaped wiring member that directly connects the DC power supply terminal 8 and the main power module 3a. The relay busbar module 7 includes a positive busbar 7a and a negative busbar 7b. The positive busbar 7a connects the positive terminal 8a of the DC power supply terminal 8 to the positive external terminal 3a6 of the main power module 3a. The negative busbar 7b connects the negative terminal 8b of the DC power supply terminal 8 to the negative external terminal 3a6 of the main power module 3a.

[0024] The DC power supply terminal 8 includes a positive terminal 8a (DC power supply terminal), a negative terminal 8b (DC power supply terminal), and a holder 8c. The positive terminal 8a is connected to the positive electrode of battery B. The positive terminal 8a is connected to the positive bus bar 7a of the relay bus bar module 7. The negative terminal 8b is connected to the negative electrode of battery B. The negative terminal 8b is connected to the negative bus bar 7b of the relay bus bar module 7. The holder 8c is a member that holds the positive terminal 8a and the negative terminal 8b, and is fixed to the inverter case 2. A filter circuit may be installed between the DC power supply terminal 8 and the relay bus bar module 7. This filter circuit removes noise components from the current flowing between the DC power supply terminal 8 and the relay bus bar module 7.

[0025] 2 is a circuit diagram showing a schematic electrical configuration of the power conversion device 1 of this embodiment. The power conversion device 1 of this embodiment includes a first inverter circuit E1, a second inverter circuit E2, and a capacitor C. The power conversion device 1 of this embodiment also includes a bus bar BU that connects the first inverter circuit E1 to a battery B and the second inverter circuit E2 to the battery B. The first inverter circuit E1 is formed by a main power module 3a. The second inverter circuit E2 is formed by a sub-power module 5a. The relay bus bar module 7 also forms a part of the bus bar BU.

[0026] The power conversion device 1 of this embodiment converts power supplied from the battery B into three-phase AC power and supplies it to the motors (first motor M1 and second motor M2). The power conversion device 1 also supplies regenerative power from the motors (first motor M1 and second motor M2) to the battery B.

[0027] As shown in FIG. 2 , a first motor M1 is connected to the first inverter circuit E1. A second motor M2 is connected to the second inverter circuit E2. The first motor M1 is, for example, a motor for driving the rear wheels of a vehicle. In this embodiment, the first motor M1 is capable of outputting more power than the second motor M2. The second motor M2 is, for example, a motor for driving the front wheels of the vehicle. In this embodiment, the second motor M2 is a motor for outputting less power than the first motor M1 and is smaller than the first motor M1.

[0028] In the power conversion device 1 of this embodiment, the first inverter circuit E1 converts power supplied from the battery B into three-phase AC power and supplies it to the first motor M1. The first inverter circuit E1 also supplies regenerated power from the first motor M1 to the battery B. In the power conversion device 1 of this embodiment, the second inverter circuit E2 converts power supplied from the battery B into three-phase AC power and supplies it to the second motor M2. The second inverter circuit E2 also supplies regenerated power from the second motor M2 to the battery B.

[0029] As shown in FIG. 2 , the first inverter circuit E1 has three legs R corresponding to the respective phases of the first motor M1. The second inverter circuit E2 has three legs R corresponding to the respective phases of the second motor M2. Each leg R has an upper arm HA and a lower arm LA. The upper arm HA is connected to the positive side of a battery B via a bus bar BU. The lower arm LA is connected to the negative side of the battery B via a bus bar BU. The upper arm HA and the lower arm LA are connected in series. An output terminal is connected between the upper arm HA and the lower arm LA, connecting the leg R to the first motor M1 or the second motor M2.

[0030] 2, the power conversion device 1 of this embodiment includes power devices D corresponding to each leg R. That is, in this embodiment, the power conversion device 1 includes six power devices D. Each power device D includes a power transistor corresponding to the upper arm HA and a power transistor corresponding to the lower arm. For example, each power transistor includes a plurality of semiconductor elements formed of, for example, SiC (silicon carbide). Note that the power transistors may include semiconductor elements formed of other materials such as Si (silicon) and GaN (gallium nitride).

[0031] As described above, in this embodiment, the first inverter circuit E1 is formed by the main power module 3a. Therefore, the main power module 3a includes three power devices D. Also, in this embodiment, the second inverter circuit E2 is formed by the sub power module 5a. Therefore, the sub power module 5a includes three power devices D.

[0032] As described above, the first motor M1 driven by the first inverter circuit E1 can output more power than the second motor M2 driven by the second inverter circuit E2. In this embodiment, the output power of the main power module 3a forming the first inverter circuit E1 over a certain period of time is greater than the output power of the sub-power module 5a forming the second inverter circuit E2 over the same period of time. Therefore, the amount of heat generated by the sub-power module 5a is smaller than the amount of heat generated by the main power module 3a.

[0033] 3 is a schematic plan view of the main power module 3a. As shown in this figure, the main power module 3a includes a module case 3a1 and the above-described power devices D. The module case 3a1 is a resin case that houses the power devices D and the like. The module case 3a1 includes an opening for each power device D to house the power device D. The module case 3a1 is fixed onto a heat sink (not shown) via, for example, an adhesive.

[0034] Each power device D is placed on a heat sink and accommodated in an opening of the module case 3a1. The heat sink supports the module case 3a1 and the power devices D. The heat sink also absorbs heat from the power devices D to cool them. Such a heat sink is fixed to the central case 2a so that the bottom surface is exposed to the flow path of the central case 2a. The heat sink may have a plurality of fins formed on the bottom surface.

[0035] The main power module 3a also includes a positive-side internal bus bar 3a2, a negative-side internal bus bar 3a3, an output-side bus bar 3a4, and a lead frame 3a5. The positive-side internal bus bar 3a2, the negative-side internal bus bar 3a3, the output-side bus bar 3a4, and the lead frame 3a5 are wide wiring members that pass current between the battery B and the first motor M1.

[0036] The positive electrode side internal bus bar 3a2 is contained within the module case 3a1 and is connected to the positive electrode terminal pad of the power device D via the lead frame 3a5. The positive electrode side internal bus bar 3a2 has external terminals 3a6 exposed to the outside of the module case 3a1. The external terminals 3a6 of the positive electrode side internal bus bar 3a2 are provided for each power device D. That is, in this embodiment, the positive electrode side internal bus bar 3a2 has three external terminals 3a6.

[0037] As described above, a power device D is provided for each phase of the first motor M1. That is, the main power module 3a includes a power device D corresponding to the U-phase of the first motor M1, a power device D corresponding to the V-phase of the first motor M1, and a power device D corresponding to the W-phase of the first motor M1. These power devices D are arranged in the order of the power device D corresponding to the U-phase, the power device D corresponding to the V-phase, and the power device D corresponding to the W-phase, from the side closest to the DC power supply terminal 8. The three external terminals 3a6 of the positive-side internal bus bar 3a2 are also arranged in the order of the external terminal 3a6 corresponding to the U-phase, the external terminal 3a6 corresponding to the V-phase, and the external terminal 3a6 corresponding to the W-phase, from the side closest to the DC power supply terminal 8. These external terminals 3a6 are connected to each other by a portion of the positive-side internal bus bar 3a2 provided inside the module case 3a1.

[0038] The negative electrode side internal bus bar 3a3 is contained in the module case 3a1 so as to face the positive electrode side internal bus bar 3a2, and is connected to the negative electrode terminal pad of the power device D via the lead frame 3a5. The negative electrode side internal bus bar 3a3 has external terminals 3a6 exposed to the outside of the module case 3a1. Like the external terminals 3a6 of the positive electrode side internal bus bar 3a2, the external terminals 3a6 of the negative electrode side internal bus bar 3a3 are also provided for each power device D. That is, in this embodiment, the negative electrode side internal bus bar 3a3 has three external terminals 3a6.

[0039] The three external terminals 3a6 of the negative-side internal bus bar 3a3 are also arranged in the order of the external terminal 3a6 corresponding to the U phase, the external terminal 3a6 corresponding to the V phase, and the external terminal 3a6 corresponding to the W phase, from the side closest to the DC power supply terminal 8. These external terminals 3a6 are connected to one another by a portion of the negative-side internal bus bar 3a3 provided inside the module case 3a1.

[0040] As described above, the main power module 3a has six external terminals 3a6. These external terminals 3a6 are arranged in a straight line at a portion of the main power module 3a on the side of the sub power module 5a. These external terminals 3a6 are connected to the relay bus bar module 7 and the capacitor module 6.

[0041] The output bus bars 3a4 are connected to the output terminal pads of the power devices D via the lead frames 3a5. An output bus bar 3a4 is provided for each of the power devices D. In other words, the main power module 3a includes three output bus bars 3a4. Each output bus bar 3a4 forms an output terminal of the first inverter circuit E1. Each of these output bus bars 3a4 is connected to the first motor M1.

[0042] A plurality of lead frames 3a5 are provided. Some of these lead frames 3a5 connect the positive electrode side internal bus bar 3a2 and each power device D. It is also possible to omit the lead frame 3a5 and directly join some of the positive electrode side internal bus bar 3a2 to the power device D. Other parts of the plurality of lead frames 3a5 connect the negative electrode side internal bus bar 3a3 and each power device D. It is also possible to omit the lead frame 3a5 and directly join some of the negative electrode side internal bus bar 3a3 to the power device D. It is also possible to omit the lead frame 3a5 and directly join the output electrode side bus bar 3a4 to each power device D. It is also possible to omit the lead frame 3a5 and directly join the output electrode side bus bar 3a4 to the power device D.

[0043] The main power module 3a also includes a plurality of control terminals and a plurality of control terminal wires. The control terminals are terminals for connecting the main power module 3a and the main substrate unit 3b. One end of each control terminal protrudes toward the main substrate unit 3b, and the other end is connected to a power device D via a control terminal wire. In other words, by connecting the control terminal to the main substrate unit 3b, each power device D included in the main power module 3a is electrically connected to the main substrate unit 3b. The control terminal wires are wire-like wiring that connect the control terminals and the power devices D, and multiple control terminal wires are connected to one power device D.

[0044] 4 is a schematic plan view of the sub-power module 5a and the relay bus bar module 7. As shown in this figure, the sub-power module 5a includes a module case 5a1 and the above-described power devices D. The module case 5a1 is a resin case that houses the power devices D and the like. The module case 5a1 includes an opening for each power device D to house the power device D. The module case 5a1 is fixed onto a heat sink (not shown) via, for example, an adhesive.

[0045] Each power device D is placed on a heat sink and accommodated in an opening of the module case 5a1. The heat sink supports the module case 5a1 and the power devices D. The heat sink also absorbs heat from the power devices D to cool them. Such a heat sink is fixed to the cooler 4 so that the bottom surface thereof is exposed to the cooler 4. The heat sink may have a plurality of fins formed on the bottom surface.

[0046] The sub-power module 5a also includes an output bus bar 5a2 and a lead frame 5a3. The output bus bar 5a2 is connected to the output terminal pads of the power devices D via the lead frame 5a3. An output bus bar 5a2 is provided for each of the power devices D. In other words, the sub-power module 5a includes three output bus bars 5a2. Each output bus bar 5a2 forms an output terminal of the second inverter circuit E2. Each of these output bus bars 5a2 is connected to the second motor M2.

[0047] A plurality of lead frames 5a3 are provided. Some of these lead frames 5a3 connect the positive bus bars 7a of the relay bus bar module 7 to each of the power devices D. It is also possible to omit the lead frames 5a3 and directly join some of the positive bus bars 7a to the power devices D. Other parts of the plurality of lead frames 5a3 connect the negative bus bars 7b of the relay bus bar module 7 to each of the power devices D. It is also possible to omit the lead frames 5a3 and directly connect some of the negative bus bars 7b to the power devices D. Other parts of the plurality of lead frames 5a3 connect the output bus bars 5a2 to each of the power devices D. It is also possible to omit the lead frames 5a3 and directly join the output bus bars 5a2 to the power devices D.

[0048] The relay busbar module 7 is a wiring module that electrically connects the DC power supply terminal 8 and the main power module 3a. The relay busbar module 7 also electrically connects the DC power supply terminal 8 and the sub-power module 5a. As shown in FIG. 4 , the relay busbar module 7 is arranged to pass through the inside of the sub-power module 5a. The relay busbar module 7 that passes through the inside of the sub-power module 5a is insert-molded into the module case 5a1. The relay busbar module 7 does not pass through the capacitor module 6 and is arranged to avoid the capacitor module 6. As described above, the relay busbar module 7 includes a positive electrode side busbar 7a and a negative electrode side busbar 7b that are arranged opposite each other. In other words, the positive electrode side busbar 7a and the negative electrode side busbar 7b are arranged to pass through the sub-power module 5a without passing through the capacitor module 6.

[0049] Fig. 5 is a perspective view of the relay bus bar module 7. As shown in Fig. 5, in this embodiment, the positive bus bar 7a is located below the negative bus bar 7b (toward the bottom wall of the central case 2a).

[0050] The positive bus bar 7a (relay bus bar) has a terminal connection terminal 7c at one end to which the positive terminal 8a of the DC power supply terminal 8 is connected. The positive bus bar 7a also has a plurality of power module connection terminals 7d that are connected to the external terminals 3a6 of the main power modules 3a. In this embodiment, the positive bus bar 7a has two power module connection terminals 7d. Each power module connection terminal 7d provided on the positive bus bar 7a is connected to the external terminal 3a6 of the positive internal bus bar 3a2 of the main power module 3a.

[0051] The positive bus bar 7 a has a main body 7 a 1 that connects the terminal connection terminal 7 c and the two power module connection terminals 7 d. The main body 7 a 1 functions as a connecting portion that connects the two power module connection terminals 7 d on the positive bus bar 7 a.

[0052] The negative bus bar 7b (relay bus bar) has a terminal connection terminal 7c at one end to which the negative terminal 8b of the DC power supply terminal 8 is connected. The negative bus bar 7b also has a plurality of power module connection terminals 7d that are connected to the external terminals 3a6 of the main power modules 3a. In this embodiment, the negative bus bar 7b has two power module connection terminals 7d. Each power module connection terminal 7d provided on the negative bus bar 7b is connected to the external terminal 3a6 of the negative internal bus bar 3a3 of the main power module 3a.

[0053] The negative bus bar 7 b has a main body 7 b 1 that connects the terminal connection terminal 7 c and the two power module connection terminals 7 d. The main body 7 b 1 functions as a connecting portion that connects the two power module connection terminals 7 d on the negative bus bar 7 b.

[0054] 6 is a schematic diagram showing the main power module 3a, the sub-power module 5a, and the relay bus bar module 7. As shown in this figure, the power module connection terminal 7d of the positive bus bar 7a of the relay bus bar module 7 is connected to the external terminal 3a6 corresponding to the U phase and the external terminal 3a6 corresponding to the V phase of the positive internal bus bar 3a2. Furthermore, the power module connection terminal 7d of the negative bus bar 7b of the relay bus bar module 7 is connected to the external terminal 3a6 corresponding to the U phase and the external terminal 3a6 corresponding to the V phase of the negative internal bus bar 3a3.

[0055] FIG. 7 is a schematic diagram showing the positional relationship between the external terminal 3a6, the power module connection terminal 7d, and the capacitor module terminal 6a. In this embodiment, the external terminal 3a6 corresponding to the U phase and the external terminal 3a6 corresponding to the V phase are connected to the power module connection terminal 7d and the capacitor module terminal 6a. As shown in FIG. 7, the power module connection terminal 7d is abutted against the external terminal 3a6 on its lower side and the capacitor module terminal 6a on its upper side. That is, the external terminal 3a6, the power module connection terminal 7d, and the capacitor module terminal 6a are stacked in this order from the lower side (the bottom wall side of the central case 2a): the external terminal 3a6, the power module connection terminal 7d, and the capacitor module terminal 6a. That is, the power module connection terminal 7d is interposed between the capacitor module terminal 6a and the external terminal 3a6. As shown in FIG. 7, the external terminal 3a6, the power module connection terminal 7d, and the capacitor module terminal 6a are fastened together by fastening members 9.

[0056] In this embodiment, the power module connection terminal 7d is not connected to the external terminal 3a6 corresponding to the W phase, and therefore the capacitor module terminal 6a is connected to the external terminal 3a6 corresponding to the W phase without going through the power module connection terminal 7d.

[0057] As described above, in this embodiment, the terminal connection terminal 7c of the positive bus bar 7a of the relay bus bar module 7 is connected to the positive terminal 8a of the DC power supply terminal 8. In other words, the positive bus bar 7a of the relay bus bar module 7 is connected to the positive electrode of the battery B. Furthermore, the power module connection terminal 7d of the positive bus bar 7a of the relay bus bar module 7 is connected to the two external terminals 3a6 of the positive internal bus bar 3a2 of the main power module 3a.

[0058] Furthermore, the terminal connection terminal 7c of the negative bus bar 7b of the relay bus bar module 7 is connected to the negative terminal 8b of the DC power supply terminal 8. In other words, the negative bus bar 7b of the relay bus bar module 7 is connected to the negative electrode of battery B. Furthermore, the power module connection terminal 7d of the negative bus bar 7b of the relay bus bar module 7 is connected to the two external terminals 3a6 of the negative internal bus bar 3a3 of the main power module 3a.

[0059] Furthermore, the capacitor module 6 has a capacitor module terminal 6a connected to one terminal of the capacitor C, which is connected to the external terminal 3a6 of the positive electrode side internal bus bar 3a2 of the main power module 3a. Further, the capacitor module 6 has a capacitor module terminal 6a connected to the other terminal of the capacitor C, which is connected to the external terminal 3a6 of the negative electrode side internal bus bar 3a3 of the main power module 3a. In other words, the capacitor module 6 is connected in parallel with the main power module 3a and the sub power module 5a to the positive electrode side bus bar 7a and the negative electrode side bus bar 7b.

[0060] In the power conversion device 1 of this embodiment, the current supplied from battery B to the first motor M1, the current supplied from battery B to the second motor M2, the current regenerated from the first motor M1 to battery B, and the current regenerated from the second motor M2 to battery B flow through the relay busbar module 7.

[0061] The current supplied from the battery B to the first motor M1 is supplied to the main power module 3a via the relay bus bar module 7 and converted from DC to AC by the first inverter circuit E1. The AC generated by the first inverter circuit E1 is supplied to the first motor M1. The current supplied from the battery B to the second motor M2 is supplied to the sub power module 5a via the relay bus bar module 7 and converted from DC to AC by the second inverter circuit E2. The AC generated by the second inverter circuit E2 is supplied to the second motor M2.

[0062] The AC regenerated from the first motor M1 is converted to DC by the first inverter circuit E1 and supplied to the battery B via the relay bus bar module 7. The AC regenerated from the second motor M2 is converted to DC by the second inverter circuit E2 and supplied to the battery B via the relay bus bar module 7.

[0063] The power conversion device 1 of this embodiment as described above includes a DC power supply terminal (positive terminal 8a or negative terminal 8b), a main power module 3a, a sub-power module 5a, a relay bus bar (positive bus bar 7a or negative bus bar 7b), and a capacitor module 6. The DC power supply terminal (positive terminal 8a or negative terminal 8b) is connected to a battery B. The main power module 3a performs power conversion. The sub-power module 5a performs power conversion and is provided separately from the main power module 3a. The relay bus bar (positive bus bar 7a or negative bus bar 7b) passes through the inside of the sub-power module 5a and is connected to an external terminal 3a6 of the main power module 3a. The relay bus bar (positive bus bar 7a or negative bus bar 7b) electrically connects the DC power supply terminal (positive terminal 8a or negative terminal 8b) to the main power module 3a and the sub-power module 5a. The capacitor module 6 is connected in parallel to the main power module 3a via the relay bus bar (positive bus bar 7a or negative bus bar 7b).

[0064] According to the power conversion device 1 of this embodiment, the relay bus bar (positive electrode side bus bar 7a or negative electrode side bus bar 7b) connecting the DC power supply terminal (positive electrode terminal 8a or negative electrode terminal 8b) and the external terminal 3a6 of the main power module 3a passes through the sub-power module 5a and is connected to the main power module 3a without passing through the capacitor module 6. This prevents the capacitor module 6 from being heated by the relay bus bar (positive electrode side bus bar 7a or negative electrode side bus bar 7b), eliminating the need to incorporate a cooler in the capacitor module 6. Therefore, the power conversion device 1 of this embodiment allows the capacitor module 6 to be made smaller.

[0065] Furthermore, the power conversion device 1 of this embodiment includes a cooler 4 that cools the sub-power module 5a. By providing the sub-power module 5a with a heat sink, it is possible to absorb heat from the relay bus bar (the positive bus bar 7a or the negative bus bar 7b) and cool the relay bus bar (the positive bus bar 7a or the negative bus bar 7b). However, by providing the cooler 4 that forcibly cools the sub-power module 5a, as in the power conversion device 1 of this embodiment, it is possible to more reliably cool the power device D and the relay bus bar (the positive bus bar 7a or the negative bus bar 7b) that are included in the sub-power module 5a.

[0066] Furthermore, in the power conversion device 1 of this embodiment, the capacitor module 6 is disposed on the opposite side of the sub-power module 5a from the cooler 4. In this embodiment, it is not necessary to forcibly cool the capacitor module 6 with the cooler 4. Therefore, the capacitor module 6 can be disposed away from the cooler 4 as in this embodiment. Therefore, the cooler 4, the sub-power module 5a, and the capacitor module 6 can be disposed in a stacked manner as in this embodiment. This allows the size of the power conversion device 1 in a plan view to be reduced compared to when the capacitor module 6 is disposed adjacent to the sub-power module 5a. Furthermore, even when the sub-power module 5a and the capacitor module 6 are stacked, the relay bus bar (the positive electrode side bus bar 7a or the negative electrode side bus bar 7b) is cooled, so heat transfer from the sub-power module 5a to the capacitor module 6 can be suppressed. Therefore, the capacitor module 6 can be disposed close to the sub-power module 5a, which prevents the power conversion device 1 from becoming large in height.

[0067] Furthermore, in the power conversion device 1 of this embodiment, the output power of the sub-power module 5a is smaller than the output power of the main power module 3a. In the power conversion device 1 of this embodiment, the relay busbar (the positive busbar 7a or the negative busbar 7b) passes through the sub-power module 5a, which generates a relatively small amount of heat. This prevents the relay busbar (the positive busbar 7a or the negative busbar 7b) from becoming too hot, and also prevents the main power module 3a from becoming too hot due to the heat from the relay busbar (the positive busbar 7a or the negative busbar 7b). Furthermore, because the relay busbar (the positive busbar 7a or the negative busbar 7b) is at a low temperature, it is possible to prevent heat from the main power module 3a from being transferred to the capacitor module 6.

[0068] In the power conversion device 1 of this embodiment, the relay bus bar (positive bus bar 7 a or negative bus bar 7 b) has a power module connection terminal 7 d connected to the external terminal 3 a6 of the main power module 3 a. The power module connection terminal 7 d is interposed between the capacitor module terminal 6 a and the external terminal 3 a6 of the main power module 3 a.

[0069] According to the power conversion device 1 of this embodiment, the capacitor module terminals 6 a can be positioned away from the main power module 3 a, which generates the greatest amount of heat, and the heat from the main power module 3 a can be prevented from being transferred to the capacitor module 6.

[0070] In the power conversion device 1 of this embodiment, the main power module 3a has a plurality of external terminals 3a6. The relay bus bar (positive electrode side bus bar 7a or negative electrode side bus bar 7b) has a plurality of power module connection terminals 7d and a main body portion 7a1 that connects the plurality of power module connection terminals 7d.

[0071] According to the power conversion device 1 of this embodiment, the AC components of the ripple current generated in the inverter circuits (the first inverter circuit E1 and the second inverter circuit E2) are canceled out in the relay bus bar (the positive bus bar 7 a or the negative bus bar 7 b), and the current flowing to the capacitor module 6 can be reduced. This makes it possible to suppress heat generation in the capacitor module 6. Furthermore, because the relay bus bar (the positive bus bar 7 a or the negative bus bar 7 b) is connected to the capacitor module 6 and the main power module 3 a at multiple locations, the inductance of the relay bus bar (the positive bus bar 7 a or the negative bus bar 7 b) can be reduced.

[0072] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 8. Note that in this embodiment, descriptions of the same parts as those in the first embodiment will be omitted or simplified.

[0073] 8 is a schematic diagram showing the main power module 3a, the sub-power module 5a, and the relay bus bar module 7 according to this embodiment. As shown in this figure, in this embodiment, the power module connection terminal 7d of the positive bus bar 7a of the relay bus bar module 7 is connected to the external terminal 3a6 corresponding to the V-phase and the external terminal 3a6 corresponding to the W-phase of the positive internal bus bar 3a2. Furthermore, the power module connection terminal 7d of the negative bus bar 7b of the relay bus bar module 7 is connected to the external terminal 3a6 corresponding to the V-phase and the external terminal 3a6 corresponding to the W-phase of the negative internal bus bar 3a3.

[0074] In other words, in this embodiment, the relay bus bar (positive bus bar 7a or negative bus bar 7b) is connected to two of the three external terminals 3a6 provided corresponding to the U phase, V phase, and W phase that are relatively far from the DC power supply terminals (positive terminal 8a and negative terminal 8b).

[0075] The power device D corresponding to the V phase is arranged so as to be sandwiched between the power device D corresponding to the U phase and the power device D corresponding to the W phase, and the length of the current path to the capacitor module 6 is longer than the power device D corresponding to the U phase and the power device D corresponding to the W phase. For this reason, when the relay bus bar is connected to the external terminal 3a6 corresponding to the U phase and the external terminal 3a6 corresponding to the V phase of the positive electrode side internal bus bar 3a2 as in the first embodiment, the amount of current supplied from the capacitor module 6 to the power device D corresponding to the V phase is smaller than that of the power device D corresponding to the U phase and the power device D corresponding to the W phase.

[0076] In contrast, in this embodiment, the relay bus bar is connected to the external terminal 3a6 corresponding to the V phase of the positive-side internal bus bar 3a2 and the external terminal 3a6 corresponding to the W phase, so that current from the battery B tends to flow to the external terminal 3a6 corresponding to the V phase, which is closest to the DC power supply terminal 8. As a result, the currents supplied to the power device D corresponding to the V phase, the power device D corresponding to the U phase, and the power device D corresponding to the W phase are equalized.

[0077] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0078] For example, in the above embodiment, the first power module of the present invention is the main power module 3a, and the second power module of the present invention is the sub-power module 5a. However, the present invention is not limited to this. The first power module may be the sub-power module, and the second power module may be the sub-power module. In such a case, the relay bus bar passes through the inside of the main power module.

[0079] In the above embodiment, the configuration including the cooler 4 that cools the sub-power module 5 a has been described. However, the present invention is not limited to this, and the cooler 4 may cool the main power module 3 a in addition to the sub-power module 5 a.

[0080] The above embodiment can also be described as follows, for example:

[0081] (Supplementary Note 1) A power conversion device comprising: a DC power supply terminal connected to a battery; a first power module that performs power conversion; a second power module that performs power conversion and is separate from the first power module; a relay bus bar that passes through the inside of the second power module to be connected to an external terminal of the first power module and that electrically connects the DC power supply terminal to the first power module and the second power module; and a capacitor module that is connected in parallel to the first power module with respect to the relay bus bar.

[0082] (Supplementary Note 2) The power conversion device according to Supplementary Note 1, further comprising a cooling unit that cools at least the second power module.

[0083] (Supplementary Note 3) The power conversion device according to Supplementary Note 2, wherein the capacitor module is disposed on the opposite side of the second power module from the cooling section.

[0084] (Supplementary Note 4) The power conversion device according to any one of Supplementary Notes 1 to 3, wherein the output power of the second power module is smaller than the output power of the first power module.

[0085] (Supplementary Note 5) The power conversion device according to any one of Supplementary Notes 1 to 4, wherein the relay bus bar has a connection terminal connected to the external terminal of the first power module, and the connection terminal is interposed between a terminal of the capacitor module and the external terminal of the first power module.

[0086] (Supplementary Note 6) The power conversion device according to Supplementary Note 5, wherein the first power module has a plurality of the external terminals, and the relay bus bar has a plurality of the connection terminals and a coupling portion that couples the plurality of connection terminals.

[0087] (Supplementary Note 7) The power conversion device according to Supplementary Note 6, wherein at least some of the plurality of external terminals are connected to each other.

[0088] (Supplementary Note 8) The power conversion device according to any one of Supplementary Notes 5 to 7, wherein the first power module includes three power devices corresponding to phases of a connected motor and three external terminals provided corresponding to the respective power devices, and the relay bus bar is connected to two of the three external terminals that are relatively far from the DC power supply terminal.

[0089] REFERENCE SIGNS LIST 1 Power conversion device 3a Main power module (first power module) 3a1 Module case 3a2 Positive electrode side internal bus bar 3a3 Negative electrode side internal bus bar 3a4 Output side bus bar 3a5 Lead frame 3a6 External terminal 3b Main board unit 4 Cooler (cooling section) 5 Sub intelligent power module 5a Sub power module (second power module) 5a1 Module case 5a2 Output side bus bar 5a3 Lead frame 5b Sub board unit 6 Capacitor module 6a Capacitor module terminal (terminal) 7 Relay bus bar module 7a Positive electrode side bus bar (relay bus bar) 7a1 Main body (connecting section) 7b Negative electrode side bus bar (relay bus bar) 7b1 Main body (connecting section) 7c Terminal connection terminal 7d Power module connection terminal (connecting terminal) 8 DC power supply terminal 8a Positive terminal (DC power supply terminal) 8b Negative terminal (DC power supply terminal) 8c Holder 9 Fastening member B Battery C Capacitor D Power device E1 First inverter circuit E2 Second inverter circuit

Claims

1. A power conversion device comprising: a DC power supply terminal connected to a battery; a first power module that performs power conversion; a second power module that performs power conversion and is separate from the first power module; a relay bus bar that passes through the inside of the second power module and is connected to an external terminal of the first power module, and that electrically connects the DC power supply terminal to the first power module and the second power module; and a capacitor module that is connected in parallel to the first power module with respect to the relay bus bar.

2. The power conversion device according to claim 1, further comprising a cooling section for cooling at least said second power module.

3. The power conversion device according to claim 2, wherein the capacitor module is disposed on the opposite side of the second power module to the cooling section.

4. A power conversion device according to any one of claims 1 to 3, characterized in that the output power of the second power module is smaller than the output power of the first power module.

5. The power conversion device according to any one of claims 1 to 3, characterized in that the relay bus bar has a connection terminal connected to the external terminal of the first power module, and the connection terminal is interposed between a terminal of the capacitor module and the external terminal of the first power module.

6. The power conversion device according to claim 5, characterized in that the first power module has a plurality of the external terminals, and the relay bus bar has a plurality of the connection terminals and a coupling portion that couples the plurality of connection terminals.

7. The power conversion device according to claim 6, wherein at least some of the plurality of external terminals are connected to each other.

8. The power conversion device according to claim 5, characterized in that the first power module comprises three power devices corresponding to the phases of the connected motor and three external terminals provided corresponding to each of the power devices, and the relay bus bar is connected to two of the three external terminals that are relatively far from the DC power supply terminal.

Images