Power conversion device

Abstract

This power conversion device is to be provided to a vehicle drive apparatus that transmits a driving force of a traction motor to a wheel, and comprises a plurality of conversion modules respectively arranged in a plurality of layers that overlap each other in the vertical direction. The weights of the conversion modules arranged in the respective layers become relatively greater in a direction from an upper layer toward a lower layer. In a gravity center region in a lower layer, an electronic component having a relatively greater weight among a plurality of electronic components constituting the corresponding one of the conversion modules in the same layer is arranged.

Description

Power Conversion Device

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

[0002] As a power conversion device, Patent Document 1 describes a power supply unit capable of converting power in a power device mounted on a vehicle, which includes a current path, a housing, an AC charger, a DC relay, a main DC / DC converter, a sub DC / DC converter, a charging integration ECU, etc.

[0003] This patent document describes a configuration in which a main DC / DC converter and a sub DC / DC converter, which are lighter than the AC charger, are arranged above the AC charger inside the housing. In other words, the document discloses a technology in which lightweight relays and the like are arranged at the top of the housing, and the heaviest AC charger is arranged at the bottom of the housing.

[0004] Japanese Patent Application Laid-Open No. 2023-567

[0005] BACKGROUND ART In hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and the like that can run on electric power, improvements in vehicle performance have created a demand for compact, high-performance power conversion systems.

[0006] Many vehicles that can run on electricity use a wheel drive unit that houses an electric motor, reduction gear, etc. in a case. Vehicles equipped with such a wheel drive unit require a power converter to supply power to the electric motor housed in the wheel drive unit.

[0007] For example, power conversion devices are increasingly incorporating high-voltage components into a single package, and these components, such as power supply modules including inverters, DC-DC converters, and chargers (OBC), contain heavy parts such as filters and transformers, so it is also necessary to consider the center of gravity balance of the entire power conversion device.

[0008] In other words, when considering a configuration in which multiple electronic components that make up a power conversion device are arranged inside a housing, if relatively heavy electronic components housed in the housing are arranged in an offset position when viewed from above, the end position of the housing will become the center of gravity, compromising the stability of the housing.

[0009] To address this issue, Patent Document 1 aims to achieve weight balance in the vertical direction by lowering the center of gravity, but there is still room for improvement in weight balance in the horizontal direction.

[0010] For these reasons, there is a demand for a power conversion device with good weight balance.

[0011] The characteristic configuration of the power conversion device of the present invention is that it is a power conversion device provided in a vehicle drive unit that transmits the driving force of a traction motor to wheels, and comprises a plurality of conversion modules each arranged in a plurality of layers that overlap in the vertical direction, and the plurality of conversion modules arranged in each layer are relatively heavier from the upper layer to the lower layer, and the center of gravity area of ​​the lower layer is where the relatively heavier electronic component of the plurality of electronic components that make up the conversion module on the same layer is arranged.

[0012] With this configuration, the weight of the multiple conversion modules increases from the upper layer to the lower layer, allowing the center of gravity of the power conversion device to be positioned at a low position. Furthermore, the conversion modules in the lower layer have relatively heavy electronic components positioned in the center of gravity area. This allows the center of gravity to be set within any desired area in a plan view, even if the lower layer contains multiple conversion modules, by positioning the heavy electronic components in the center of gravity area. Therefore, a power conversion device with good weight balance has been constructed.

[0013] 1 is a longitudinal cross-sectional view of a vehicle drive device accommodating a conversion module; 2 is a perspective view of a power conversion device equipped with an inverter; 3 is an exploded perspective view of a power conversion device; 4 is a plan view showing the position of the center of gravity of the power conversion device; 5 is a longitudinal cross-sectional view showing the position of the center of gravity and the height of the center of gravity of the power conversion device; 6 is a cooling circuit diagram showing coolant flow paths and refrigerant flow paths; 7 is a power conversion circuit diagram of the power conversion device; 8 is an exploded perspective view of a vehicle drive device and a housing of another embodiment (e).

[0014] An embodiment of a power conversion device B according to the present disclosure will be described below with reference to the drawings. In this embodiment, the power conversion device B is configured by stacking a plurality of conversion modules vertically. However, the number of conversion modules and the specific arrangement of the electronic components constituting the conversion modules are not limited to the following embodiment, and various modifications are possible within the scope of the gist thereof.

[0015] 1 shows a vehicle drive device A that transmits the driving force of a drive motor M to wheels (not shown). This vehicle drive device A accommodates the drive motor M, a gear mechanism Ge that reduces the driving force of the drive motor M and transmits it to the drive wheels, a power conversion device B, and an inverter C in a housing AH.

[0016] Since the vehicle drive device A is provided on the vehicle in the up-down relationship shown in Fig. 1, in this embodiment, the up-down relationship will be described based on the up-down direction shown in Fig. 1. Also, Fig. 1 shows a vertical cross section of the vehicle drive device A as seen in the front-rear direction, and the horizontal direction in Fig. 1 corresponds to the width direction of the vehicle body.

[0017] As shown in Fig. 7, the power conversion device B converts AC power from an AC power source (basically a commercial power source) supplied from outside the vehicle into high-voltage DC power. The power converted into high-voltage DC in this manner is charged into a main battery BAT1 (see Fig. 7) external to the vehicle drive device A.

[0018] The inverter C converts DC power from the main battery BAT1 into three-phase AC power, controls the frequency, and supplies the AC power to the traction motor M, thereby enabling the vehicle to travel.

[0019] Furthermore, power conversion device B converts DC power from main battery BAT1 into AC power similar to that of a commercial power source and supplies the AC power to the outside of the vehicle. That is, in this embodiment, power conversion device B is provided in a vehicle having a power configuration similar to that of a plug-in hybrid electric vehicle (PHEV). Details of this power conversion circuit will be described later.

[0020] As shown in FIG. 1, the power conversion device B is formed of multiple layers in which multiple conversion modules (first conversion module Ba, second conversion module Bb, third conversion module Bc) are arranged in an overlapping manner in the vertical direction.

[0021] The power conversion device B sets the center of gravity position in the vertical direction (center of gravity height GL) by increasing the relative weight of the layers toward the lower end. Furthermore, the power conversion device B sets the center of gravity position in a plan view (planar center of gravity position GS, see FIG. 4 ) by arranging multiple electronic components. Therefore, vehicles equipped with the power conversion device B are not limited to plug-in hybrid vehicles, and the power conversion device B can also be equipped in hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), and fuel cell electric vehicles (FCEVs).

[0022] The power conversion device B has a single center of gravity for the entire plurality of conversion modules Ba, Bb, and Bc, including the cooling plates 11 and 12 and electronic components. The vertical position of this center of gravity is referred to as the center of gravity height GL (see FIG. 5), and the position of the center of gravity in a planar view is referred to as the planar center of gravity position GS (see FIG. 4). Details of this center of gravity position will be described later. In this embodiment, the planar center of gravity position GS of the power conversion device B is set to a position that overlaps the center of gravity positions GSa and GSb of the cooling plates 11 and 12 in a planar view.

[0023] [Vehicle drive device] As shown in Figure 1, the vehicle drive device A accommodates a driving motor M and a gear mechanism Ge in a lower space LS of a housing AH, and the outer part of the driving motor M in the lower space LS is closed by a motor cover 1, and the outer part of the gear mechanism Ge in the lower space LS is closed by a gear cover 2.

[0024] The vehicle drive device A accommodates a power conversion device B and an inverter C in an upper space HS of a housing AH. This upper space HS is closed by an upper cover 3. The lower space LS and the upper space HS are independent spaces that do not communicate with each other.

[0025] As shown in Figures 1 and 5, the power conversion device B has multiple layers in which multiple conversion modules (first conversion module Ba, second conversion module Bb, third conversion module Bc) are arranged in a stacked state, and an inverter C is provided on the upper surface of the power conversion device B.

[0026] In this embodiment, as described above, the power conversion device B and the inverter C are housed in an integrated state inside the housing AH of the vehicle drive device A, but the power conversion device B may be configured to be separated from the inverter C. Furthermore, the vehicle drive device A is configured to house both the power conversion device B and the inverter C inside, but at least one of the power conversion device B and the inverter C may be disposed on the outer wall surface of the housing AH of the vehicle drive device A or outside.

[0027] 1, the power conversion device B has a first conversion module Ba, a second conversion module Bb, and a third conversion module Bc arranged in this order from top to bottom. The power conversion device B has a first cooling plate 11 arranged on the upper level, and a second cooling plate 12 arranged below it at a set distance, and these are connected via a spacer or the like to maintain the set distance between the first cooling plate 11 and the second cooling plate 12.

[0028] Specifically, in the power conversion device B, the first conversion module Ba and the second conversion module Bb are arranged below the first cooling plate 11 and above the second cooling plate 12, and the third conversion module Bc is arranged below the second cooling plate 12. Furthermore, the inverter C is arranged above the first cooling plate 11. The cooling plates 11 and 12 (an example of a support member) support multiple electronic components that make up the conversion modules Ba, Bb, and Bc on the same layer.

[0029] The first conversion module Ba is mounted on the upper surface of an upper substrate 14 supported on the lower surface side of the first cooling plate 11, and includes a plurality of switching elements 15 (an example of electronic components).

[0030] 1, a plurality of switching elements 15 are shown as one block. These switching elements 15 are arranged in contact with or in close proximity to the lower surface of the first cooling plate 11.

[0031] 3, the second conversion module Bb includes, on the underside of the upper substrate 14, a transformer T (an example of an electronic component), multiple bulk capacitors 16 (an example of an electronic component), and a frame member 18 that functions as a spacer by protruding downward and surrounding part of the outer periphery of the transformer T. The multiple bulk capacitors 16 and the transformer T are electronic components that are relatively heavy compared to other electronic components arranged on the same layer, and the transformer T is also heavier than the bulk capacitor 16. The bottom surfaces of the multiple bulk capacitors 16 and the bottom surface of the transformer T are arranged in contact with or in close proximity to the top surface of the second cooling plate 12.

[0032] 1 and 3, the third conversion module Bc includes a coil module 21 (an example of an electronic component) and a plurality of AC filters 22 (an example of an electronic component / an example of a filter substrate) on the upper surface of a lower substrate 20 that is disposed separately below the lower surface of the second cooling plate 12. The coil module 21 and the plurality of AC filters 22 are electronic components that are relatively heavy compared to other electronic components disposed on the same layer, and the AC filters 22 are also heavier than the coil module 21.

[0033] The upper surface of the coil module 21 and the upper surfaces of the plurality of AC filters 22 are arranged in contact with or in close proximity to the lower surface of the second cooling plate 12 .

[0034] The center of gravity position and other information relating to these multiple conversion modules (first conversion module Ba, second conversion module Bb, third conversion module Bc) will be described later.

[0035] [Cooling Circuit] The first cooling plate 11 and the second cooling plate 12 have flow paths for flowing a cooling fluid, and by flowing a cooling liquid such as ethylene glycol, long-life coolant (LLC) containing propylene glycol, or the like, or insulating oil through the flow paths, it is possible to cool both the upper and lower surfaces.

[0036] As shown in FIG. 6, the vehicle drive device A has a cooling circuit consisting of a coolant flow path L1 for circulating a cooling fluid, a refrigerant flow path L2 for circulating a refrigerant, and a lubricant flow path L3 for circulating a lubricant.

[0037] The coolant flow path L1 circulates the coolant through the first cooling plate 11 and second cooling plate 12 of the power conversion device B, the water-cooled condenser 31, the oil cooler 32, and the radiator 34 in this order, when driven by the coolant pump 33.

[0038] The refrigerant flow path L2 is configured to supply the refrigerant to the water-cooled condenser 31. In this refrigerant flow path L2, a hydrofluorocarbon (HFC), a hydrofluoroolefin (HFO), or the like is used as the refrigerant.

[0039] The lubricating oil passage L3 supplies low-temperature lubricating oil to the inside of the traveling motor M and the gear mechanism Ge when driven by the hydraulic pump 35.

[0040] In this cooling circuit, the coolant cooled by the radiator 34 flows through the first cooling plate 11 and the second cooling plate 12 of the power conversion device B, and then flows through the first conversion module Ba, the second conversion module Bb and the third conversion module Bc, and the temperature rises by removing heat from the electronic components.

[0041] The coolant whose temperature has risen in this way absorbs heat from the refrigerant in the water-cooled condenser 31 and is supplied to the oil cooler 32. This reduces the temperature of the lubricating oil flowing in the lubricating oil flow path L3, and suppresses the temperature rise of the driving motor M and the gear mechanism Ge in the lower space LS of the housing AH.

[0042] Furthermore, the coolant that has passed through the oil cooler 32 dissipates heat in the radiator 34, thereby lowering its temperature, and is then supplied to the power conversion device B again.

[0043] [Power Conversion Circuit] Fig. 7 shows the power conversion circuit of the power conversion device B. As shown in Fig. 7, the power conversion circuit includes a filter unit 40, an OBC (abbreviation for on board charger) unit 50, an auxiliary inverter unit 60 (an example of an inverter C), a main inverter unit 65 (an example of an inverter C), and a control unit D.

[0044] [Power Conversion Circuit: Filter Unit] The filter unit 40 includes an input connector 40 a , an output connector 40 b , an AC filter 22 , a relay module 42 , a coil module 21 , a current detection module 44 , and an input / output control unit 45 .

[0045] The coil module 21 of the filter unit 40 and the plurality of AC filters 22 are provided in a third conversion module Bc, as shown in FIGS.

[0046] In addition, the input / output control unit 45 outputs a control signal to the relay module 42 and acquires a detection signal from the current detection module 44 .

[0047] [Power Conversion Circuit: OBC Unit] As shown in Figure 7, the OBC unit 50 includes a transformer T, a conversion circuit 51, a primary coil control circuit 52 that controls the primary coil T1 of the transformer T, a bulk capacitor 16 provided in the power system that transmits power from the conversion circuit 51 to the primary coil control circuit 52, a secondary coil control circuit 54 that controls the secondary coil T2 of the transformer T, and a tertiary coil control circuit 55 that obtains power from the tertiary coil T3 of the transformer T.

[0048] The OBC unit 50 includes a conversion circuit control unit 56, a transformer control unit 57, and a low-voltage control unit 58. The OBC unit 50 includes a low-voltage connector 50a that supplies power from the tertiary coil control circuit 55 to a low-voltage system battery BAT2.

[0049] In this OBC unit 50, a plurality of switching elements 15 constituting a part of a conversion circuit 51, a primary coil control circuit 52, a secondary coil control circuit 54, etc. are mounted on the upper surface of an upper substrate 14 in a first conversion module Ba.

[0050] 1 and 3, the transformer T and the plurality of bulk capacitors 16 of the OBC unit 50 are mounted on the underside of the upper substrate 14 and provided in the second conversion module Bb. Note that the transformer T, the plurality of bulk capacitors 16, and related elements may be provided on a substrate different from the upper substrate 14.

[0051] 7 , the conversion circuit control unit 56 controls the multiple switching elements of the conversion circuit 51. The transformer control unit 57 controls the primary coil control circuit 52 and the secondary coil control circuit 54. The low voltage control unit 58 controls the tertiary coil control circuit 55.

[0052] 7, the auxiliary inverter unit 60 (an example of an inverter) functions as a DC-DC converter and includes an auxiliary drive circuit 61, a DC filter 62, and an auxiliary control unit 63. The auxiliary inverter unit 60 includes a first high-voltage connector 60a.

[0053] The auxiliary drive circuit 61 includes a plurality of switching elements. The auxiliary control unit 63 controls the auxiliary drive circuit 61 to supply high-voltage power to auxiliary devices such as the air conditioner 5 via the first high-voltage connector 60a.

[0054] As shown in FIG. 2, the auxiliary inverter unit 60 is disposed above the first cooling plate 11 in a region that protrudes outward from the first cooling plate 11 in a plan view.

[0055] 7, the main inverter unit 65 (an example of an inverter) includes a second high-voltage connector 65a, a motor drive circuit 66, and a smoothing capacitor 67. The motor drive circuit 66 has a plurality of switching elements and supplies power to the traction motor M.

[0056] 2, the smoothing capacitor 67 is disposed above the first cooling plate 11. The motor drive circuit 66 is disposed adjacent to the smoothing capacitor 67.

[0057] This main inverter unit 65 functions to supply high-voltage power flowing between the OBC unit 50 and the auxiliary inverter unit 60, and to supply this high-voltage power from the second high-voltage connector 65a to the main battery BAT1 to charge it.

[0058] The main inverter unit 65 converts the power from the main battery BAT1 into three-phase AC power using the motor drive circuit 66, controls the frequency and supplies it to the traction motor M, thereby obtaining driving force from the traction motor M that enables the vehicle to run.

[0059] [Power Conversion Circuit: Control Unit] As shown in FIG. 7, the control unit D outputs control signals to the input / output control unit 45 , the conversion circuit control unit 56 , the transformer control unit 57 , the low voltage control unit 58 , and the auxiliary control unit 63 .

[0060] As shown in FIG. 2, the control unit D is disposed above the first cooling plate 11 and adjacent to the smoothing capacitor 67 .

[0061] [Power Conversion Circuit: Current Flow] The power conversion circuit converts AC power from an AC power source (basically a commercial power source) supplied from outside the vehicle to the input connector 40 a under the control of the relay module 42 into DC power using the conversion circuit 51, and supplies AC of a set frequency generated by the primary coil control circuit 52 to the primary coil side of the transformer T.

[0062] The high voltage power output to the secondary coil side of the transformer T is extracted as high voltage DC power by the secondary coil control circuit 54 and charged into the main battery BAT1 from the second high voltage connector 65a.

[0063] The high-voltage DC power of the main battery BAT1 is converted to three-phase AC power by the motor drive circuit 66, and the frequency is controlled before being supplied to the traction motor M, thereby driving the traction motor M at a target rotational speed and realizing vehicle travel. In addition, the high-voltage DC power from the main battery BAT1 is DC-DC converted by the accessory drive circuit 61 and supplied to the air conditioner 5 and the like from the first high-voltage connector 60a.

[0064] In response to this, the low-voltage power output to the tertiary coil side of the transformer T is converted into DC power by the tertiary coil control circuit 55 and charged into the system battery BAT2 from the low-voltage connector 50a. The power charged into the system battery BAT2 in this manner is supplied to the vehicle control device and other control equipment.

[0065] Furthermore, under the control of the relay module 42, the power conversion circuit supplies power from the main battery BAT1 to the secondary coil control circuit 54, the transformer T, the primary coil control circuit 52, etc. in sequence, thereby creating AC power similar to that of a commercial power source and outputting it from the output connector 40b.

[0066] [Arrangement of electronic components, etc. of the power conversion device] As shown in Figures 1, 4, and 5, the power conversion device B is constructed by arranging multiple conversion modules (first conversion module Ba, second conversion module Bb, third conversion module Bc) in each of multiple (three in this embodiment) layers that overlap vertically.

[0067] The power converter B includes a plurality of electronic components whose weights increase toward the lower layers. The power converter B also includes a plurality of electronic components such that the heavier electronic components among the plurality of electronic components on the same lower layer are arranged relative to a center-of-gravity region GF. The center-of-gravity region GF is a region centered on the centers of gravity GSa and GSb of the cooling plates 11 and 12, respectively, in a plan view. In this embodiment, the center-of-gravity GSa of the first cooling plate 11 and the center-of-gravity GSb of the second cooling plate 12 overlap (are at the same position) in a plan view.

[0068] As a specific arrangement, the lowermost layer (third conversion module Bc) of the conversion module of the power conversion device B includes an AC filter 22 (an example of a filter substrate) and a coil module 21 as relatively heavy electronic components, and the AC filter 22 is relatively heavier than the coil module 21. Also, the second layer (second conversion module Bb) above the lowermost layer includes a transformer T and multiple bulk capacitors 16 as relatively heavy electronic components, and the transformer T is relatively heavier than the bulk capacitors 16.

[0069] In this power conversion device B, the top layer (first conversion module Ba) equipped with multiple switching elements 15 as electronic components is the lightest, followed by the middle layer (second conversion module Bb) and the bottom layer (third conversion module Bc). Due to this weight trend, the bottom layer of the power conversion device B is the heaviest, followed by the middle layer. As a result, the center of gravity of the power conversion device B is set at a position closest to the bottom in the vertical direction, and the center of gravity in the vertical direction is stable.

[0070] The position of the center of gravity of the power conversion device B, which is specified in the vertical direction in this manner, is referred to as the center of gravity height GL. In this embodiment, the center of gravity height GL is located at the same position as the second cooling plate 12 in the vertical direction.

[0071] In this power conversion device B, a center of gravity region GF is set as an area set in a plan view for the lowest layer (third conversion module Bc) and the second lowest layer (second conversion module Bb), as shown in Figures 4 and 5. Here, the center of gravity region GF is an area centered on the center of gravity GSb of the second cooling plate 12 in a plan view.

[0072] This center of gravity area GF is where the AC filter 22 (an example of a filter substrate), the coil module 21, the transformer T, and multiple bulk capacitors 16 are arranged as electronic components that are relatively heavy compared to the conversion modules (second conversion module Bb, third conversion module Bc). In particular, by arranging the AC filter 22 and the transformer T in the center of gravity area GF, the weight balance is adjusted.

[0073] In this embodiment, the center of gravity of the power conversion device B, which is identified in a planar view, is referred to as the planar center of gravity position GS, and the centers of gravity of the cooling plates 11, 12 are referred to as center of gravity positions GSa and GSb. In this embodiment, the cooling plates 11, 12 and electronic components (such as the AC filter 22, coil module 21, transformer T, and bulk capacitor 16) are arranged so that the planar center of gravity position GS of the power conversion device B overlaps with the center of gravity positions GSa and GSb of each cooling plate 11, 12 in a planar view. Furthermore, the planar center of gravity position GS and each center of gravity position GSa and GSb are located near the center of the power conversion device B in a planar view.

[0074] In the power conversion device B, the centers of gravity GSa and GSb of the cooling plates 11 and 12 are located at a single fixed position. In this embodiment, as shown in Figures 4 and 5, the center of gravity height GL and the centers of gravity GSa and GSb of the cooling plates 11 and 12 overlap in a plan view. The planar center of gravity GS also overlaps with the centers of gravity GSa and GSb of the first and second cooling plates 11 and 12 in a plan view. In the second conversion module Bb of this embodiment, the frame member 18 has a thick portion 18a formed at a position that allows balance to be achieved at the planar center of gravity GS. This allows the planar center of gravity GS to be set to an ideal position (in this embodiment, the position overlaps with the centers of gravity GSa and GSb of the cooling plates 11 and 12 in a plan view, improving the overall balance of the power conversion device B). 3, in this embodiment, the thick portion 18a is formed by increasing the thickness of the frame member 18 in the center of gravity region GF compared to the thickness of the frame member 18 outside the center of gravity region GF. In other words, the thick portion 18a is formed by increasing the thickness of the frame member 18 around a relatively heavy electronic component compared to the thickness of the frame member 18 outside the periphery of the electronic component.

[0075] [Effects of the embodiment] The power conversion device B, in which a plurality of conversion modules are stacked, and the inverter C are integrated and housed in the upper space HS of the housing AH, which allows the power conversion device B and the inverter C to be treated as an integrated unit.

[0076] The power converter B has multiple (three in this embodiment) layers, each of which is configured with a first conversion module Ba, a second conversion module Bb, and a third conversion module Bc. The weight of the power converter B increases toward the lower layers. This positions the center of gravity (center of gravity height GL) below the power converter B in the vertical direction, improving the stability of the vehicle body.

[0077] Furthermore, in the power converter B of this embodiment, the center of gravity region GF in the lower layer is set to an area centered on the center of gravity GSb of the second cooling plate 12 in a plan view, and relatively heavy components are arranged in this center of gravity region GF. As a result, the planar center of gravity GS overlaps with the center of gravity GSb of the second cooling plate 12 in a plan view and is arranged near the center of the power converter B, thereby improving the balance of the power converter B in the width direction of the vehicle body.

[0078] In the power conversion device B, the thickened portion 18a of the frame member 18 that constitutes part of the conversion module is increased in order to set the planar center of gravity position GS. With this configuration, even if there are restrictions on the placement of electronic components on the board, the weight of the thickened portion 18a makes it possible to set the planar center of gravity position GS within the center of gravity region GF. In this embodiment, the frame member 18 functions as a spacer and does not increase the number of parts compared to a configuration that uses, for example, a metal balancer.

[0079] For example, when a case for accommodating the power conversion device B is provided, it is possible to increase the thickness of a part of the wall of the case so that it functions as the frame member 18 .

[0080] Moreover, the power conversion device B does not experience an excessive temperature rise because it is cooled by the coolant flowing through the first cooling plate 11 and the second cooling plate 12. Similarly, the inverter C does not experience an excessive temperature rise because it is cooled by the coolant flowing through the first cooling plate 11.

[0081] Other Embodiments The present disclosure may be configured as follows in addition to the above-described embodiments (common numbers and symbols are used to denote components having the same functions as those in the embodiments).

[0082] (a) In the above embodiment, the power conversion device B is located at a position where the center of gravity GSa of the first cooling plate 11 and the center of gravity GSb of the second cooling plate 12 overlap (the same position) in a plan view. However, the center of gravity GSa of the first cooling plate 11 and the center of gravity GSb of the second cooling plate 12 may be located at a position where they do not overlap (different positions) in a plan view. In this case, the planar center of gravity GS may be set at a position where it does not overlap one or both of the two center of gravity GSa and GSb in a plan view.

[0083] (b) Instead of integrating the power conversion device B and the inverter C and accommodating them inside the housing AH of the vehicle drive device A, as partially described in the embodiment, the power conversion device B and the inverter C may be separated. Also, although the vehicle drive device A is configured to accommodate both the power conversion device B and the inverter C inside, at least one of the power conversion device B and the inverter C may be provided outside the housing AH of the vehicle drive device A.

[0084] (c) The number of layers of the conversion module is not limited to three, but may be two, four, or more. Furthermore, the transformer T and filters, which are heavy, are not limited to being arranged in the lowest layer, but some of them may be arranged in a conversion module above the lowest conversion module.

[0085] (d) Ideally, the lowest conversion module (third conversion module Bc) of the multiple conversion modules (first conversion module Ba, second conversion module Bb, third conversion module Bc) that make up the power conversion device B should be the heaviest, but for example, the second conversion module Bb may also be the heaviest.

[0086] (e) When using a cooling plate to cool multiple conversion modules, it is possible to arrange the cooling plate so that it preferentially removes heat from electronic components that generate a large amount of heat. In this way, by using a cooling plate that removes heat from only some of the multiple electronic components, the cooling plate can be made compact.

[0087] (f) Figure 8 shows a vehicle drive device A that transmits the driving force of a drive motor M to wheels (not shown) in a housing AH. This vehicle drive device A accommodates the drive motor M, a gear mechanism Ge that reduces the driving force of the drive motor M and transmits it to the drive wheels, a power conversion device B, and an inverter C in the housing AH.

[0088] The housing AH includes a first housing chamber E1 that houses the drive motor M, and a second housing chamber E2 that houses a power converter B and an inverter C that control the power supplied to the drive motor M. The direction along the axis A1 of the drive motor M is defined as the axial direction L, the direction perpendicular to the axis A1 when viewed from above is defined as the axial direction Y, and one side of the axial direction Y is defined as a first axial direction side Y1.

[0089] The housing AH has a first cover 101 that closes the outside of the drive motor M in the first accommodation chamber E1, and a second cover 102 that closes the outside of the gear mechanism Ge in the first accommodation chamber E1. In addition, an upper opening of the housing AH is closed by an upper cover 103. This gives the housing AH a sealed structure.

[0090] The gear mechanism Ge comprises a differential gear mechanism 110 arranged on the same axis as the axis A1 of the driving motor M, and a counter gear mechanism 111 arranged on an offset axis B1 offset from the axis A1.

[0091] When mounted on a vehicle, the second storage chamber E2 has an upper region E3 which is above the driving motor M and overlaps with the driving motor M when viewed in the vertical direction, and a lateral region E4 which is on the first side Y1 perpendicular to the axis of the driving motor M and does not overlap with the driving motor M when viewed in the vertical direction.

[0092] The power conversion device B has an inverter C at the top that controls the power supplied to the driving motor M, and at least a part of the inverter C is arranged in the upper region E3, and the conversion module 104 of the power conversion device B is arranged in an area extending downward from the inverter C in the lateral region E4.

[0093] That is, in this alternative embodiment (e), when viewed in the direction along the axial direction L (side view), if the inverter C is in a horizontal position, the power conversion device B extends in the vertical direction along the up-down direction Z, and therefore the inverter C and the power conversion device B are formed in an inverted L shape. As a result, the inverter C is arranged in a horizontal position above the traction motor M in an area extending in the axially orthogonal direction Y in the upper area E3 of the second accommodation chamber E2, and the power conversion device B is arranged in a lateral area E4 extending in the vertical direction in the second accommodation chamber E2.

[0094] In this alternative embodiment (e), the side opposite to the first side Y1 in the axial direction is called the second side Y2 in the axial direction, and either the first side Y1 in the axial direction orthogonal to the first side Y1 or the second side Y2 in the axial direction orthogonal to the first side Y1 or the second side Y2 in the axial direction may be the front side of the vehicle body.

[0095] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present disclosure are not limited to these, and can be modified as appropriate within the scope of not departing from the purpose of the present disclosure.

[0096] The above-described embodiment may have the following configuration: (1) A power conversion device (B) provided in a vehicle drive device (A) that transmits the driving force of a traction motor (M) to wheels includes a plurality of conversion modules (Ba, Bb, Bc) arranged in a plurality of layers that overlap in the vertical direction, the plurality of conversion modules (Ba, Bb, Bc) arranged in each layer becoming heavier from the upper layer to the lower layer, and the heavier electronic components among the plurality of electronic components that make up the conversion modules in the same layer are arranged in a center-of-gravity region (GF) in the lower layer.

[0097] According to this configuration, the layers formed by the multiple conversion modules (Ba, Bb, Bc) are relatively heavier from the upper layers to the lower layers. This allows the center of gravity (center of gravity height GL) of the power conversion device (B) to be set at a low position. Furthermore, since the conversion modules (Bb, Bc) in the lower layers have heavier electronic components arranged in the center of gravity region GF, even if the lower layers are made up of multiple conversion modules (Bb, Bc), the center of gravity (planar center of gravity position GS) can be set at any position in a plan view by arranging the heavier electronic components in the center of gravity region (GF).

[0098] (2) It is preferable that the power conversion device (B) of (1) has support members (11, 12) that support multiple electronic components that constitute the conversion module on the same layer, and the center of gravity region (GF) is a region centered on the center of gravity position (GSa, GSb) of the support members (11, 12) in a planar view.

[0099] This allows the multiple electronic components that make up the conversion module to be positioned and supported near the center of gravity (GSa, GSb) of the support members (11, 12), so that the power conversion device (B) can stably hold the multiple electronic components.

[0100] (3) In the power converter B of (2), the support members (11, 12) are preferably cooling plates (11, 12) that have flow paths through which a cooling fluid flows and are capable of cooling electronic components.

[0101] According to this, the plurality of electronic components constituting the conversion modules (Ba, Bb, Bc) can be cooled by the support members (11, 12), so that heat generation of the power conversion device (B) can be suppressed.

[0102] (4) It is preferable that the power conversion device (B) of any of (1) to (3) includes a housing (AH) that houses a plurality of conversion modules (Ba, Bb, Bc) and has a frame member (18) that supports the conversion modules (Ba, Bb, Bc), and that the housing (AH) has a thick portion (18a) formed by increasing the thickness of the frame member (18) around relatively heavy electronic components.

[0103] As a result, for example, by increasing the weight of a part of the frame member (18) of the housing (AH) that houses the conversion modules (Ba, Bb, Bc), or of the thick portion (18a) of the frame member (18) that functions as a spacer, it is possible to improve balance by positioning the center of the center of gravity area (GF) as the center of gravity position (planar center of gravity position GS) in a planar view.

[0104] (5) It is preferable that the power conversion device (B) of any of (1) to (3) includes a housing (AH) that houses a plurality of conversion modules (Ba, Bb, Bc) and has a frame member (18) that supports the conversion modules (Ba, Bb, Bc), and that the housing (AH) has a thick portion (18a) formed around a relatively heavy electronic component in which the thickness of the frame member (18) in the center of gravity region (GF) is greater than the thickness of the frame member (18) outside the center of gravity region (GF).

[0105] As a result, for example, by increasing the weight of the thick portion (18a) of the frame member (18) of the housing (AH) that accommodates the conversion modules (Ba, Bb, Bc) by increasing the thickness of the portion located in the center of gravity region (GF), it is possible to improve balance by making the center of the center of gravity region (GF) the center of gravity position (planar center of gravity position GS) when viewed in a plane.

[0106] (6) In the power conversion device (B) of any one of (1) to (3), it is preferable that the relatively heavy electronic component in the lowest layer is a filter substrate (AC filter 22), and that the relatively heavy electronic component in the second lowest layer is a transformer (T).

[0107] According to this, by providing a relatively heavy filter substrate (AC filter 22) in the lowest layer of the layers made up of conversion modules (Ba, Bb, Bc) and providing a transformer (T) in the second layer above the lowest layer, the weight of the lower part of the power conversion device (B) can be made greater than the weight of the upper part of the power conversion device (B), thereby improving stability.

[0108] (7) It is preferable that the inverter (C) that controls the power supplied to the traction motor by the power conversion device B of any one of (1) to (3) is arranged on the uppermost layer.

[0109] This allows the power conversion device (B) and the inverter (C) to be integrated and can be treated as an integrated unit. Also, by arranging the inverter (C), which generates a relatively large amount of heat, above the power conversion device (B), the effect of heat from the inverter (C) on the power conversion device (B) can be suppressed.

[0110] (8) In the power conversion device (B) of (2), it is preferable that the heaviest electronic component among the multiple electronic components constituting the conversion modules (Ba, Bb, Bc) on the same layer is positioned so as to overlap the center of gravity (GSa, GSb) of the support member (11, 12) in a planar view.

[0111] As a result, the heaviest electronic component among the multiple electronic components constituting the conversion module on the same layer is placed at the center of gravity (GSa, GSb) of the support members (11, 12) of the power conversion device (B), so that the power conversion device (B) can stably hold the conversion modules (Ba, Bb, Bc) using the support members (11, 12).

[0112] In the power conversion device (B) of (9) and (8), the plurality of electronic components are preferably a transformer (T) and a bulk capacitor (16), and the heaviest electronic component is preferably the transformer (T).

[0113] According to this, the power conversion device (B) has multiple electronic components, including a transformer (T) and a bulk capacitor (16), and the transformer (T), which is the heaviest electronic component, is positioned at the center of gravity (GSb) of the support member (12), thereby enabling the conversion module (Bb) to be stably held.

[0114] In the power conversion device (B) of (10) (8), the plurality of electronic components are a filter substrate (22) and a coil module (21), and it is preferable that the heaviest electronic component is the filter substrate (22).

[0115] According to this, the power conversion device (B) has a filter substrate (22) and a coil module (21) as multiple electronic components, and the filter substrate (22), which is the heaviest electronic component, is positioned at the center of gravity (GSb) of the support member (12), thereby enabling the conversion module (Bc) to be stably held.

[0116] (Supplementary clause) (11) A vehicle drive device (A) having a power conversion device according to any one of (1) to (3) is provided with a housing (AH) including a first accommodation chamber (E1) for accommodating a driving motor (M) and a second accommodation chamber (E2) for accommodating a power conversion device (B) for controlling power supplied to the driving motor (M), wherein the direction along the axis (A1) of the driving motor (M) is defined as an axial direction (L), the direction perpendicular to the axis (A1) as viewed in the up-down direction is defined as an axial orthogonal direction (Y), one side of the axial orthogonal direction (Y) is defined as an axial orthogonal direction first side (Y1), and the second accommodation chamber (E2) is configured to accommodate a driving motor (M) when mounted on a vehicle. The power conversion device (B) has an upper region (E3) that is above the driving motor (M) and overlaps with the driving motor (M) when viewed in the up-down direction, and a lateral region (E4) that is on the first side (Y1) in the direction perpendicular to the axis of the driving motor (M) and does not overlap with the driving motor (M) when viewed in the up-down direction, and the power conversion device (B) has an inverter (C) at the top that controls the power supplied to the driving motor (M), at least a part of the inverter (C) is arranged in the upper region (E3), and the power conversion device (B) is arranged in a region in the lateral region (E4) that extends below the inverter (C).

[0117] According to this configuration, the inverter (C) provided in the power conversion device (B) is disposed in the upper region (E3) above the traction motor (M), and the power conversion device (B) is disposed in the side region (E4) that does not overlap with the traction motor (M). This arrangement makes it possible to effectively utilize the upper side of the traction motor (M) and the side region (E4) adjacent to the traction motor (M) in the axis-orthogonal direction (Y) to place the inverter (C) and the power conversion device (B).

[0118] (12) In the vehicle drive device (A) of (11), it is preferable that the power conversion device (B) has a configuration in which a plurality of conversion modules (104) are stacked vertically in the side region (E4).

[0119] This allows the power converter (B) to be housed in the housing (AH) even if it is long in the vertical direction, such as when a plurality of conversion modules (104) are stacked.

[0120] The present invention can be used in a power conversion device.

[0121] A: vehicle drive device, A1: shaft core, AH: housing, B: power conversion device, M: traction motor, BAT1: battery, Ba: first conversion module (conversion module), Bb: second conversion module (conversion module), Bc: third conversion module (conversion module), C: inverter, E1: first housing chamber, E2: second housing chamber, E3: upper region, E4: side region, GF: center of gravity region, GSa: center of gravity position, GSb: center of gravity position, L: axial direction, T: transformer, Y: direction perpendicular to axis, Y1: first side in direction perpendicular to axis, 11: first cooling plate (support member), 12: second cooling plate (support member), 15: switching element (electronic component), 16: bulk capacitor (electronic component), 18: frame member, 18a: thick portion, 21: coil module (electronic component), 22: AC filter (electronic component / filter board), 104: conversion module

Claims

1. A power conversion device provided in a vehicle drive device that transmits the driving force of a driving motor to wheels, the power conversion device comprising a plurality of conversion modules respectively arranged in a plurality of layers overlapping in the vertical direction, the plurality of conversion modules arranged in each of the layers being relatively heavier from the upper layer to the lower layer, and the lower layer has a center of gravity region in which the relatively heavier electronic components of the plurality of electronic components constituting the conversion modules in the same layer are arranged.

2. A power conversion device as described in claim 1, further comprising a support member that supports the plurality of electronic components constituting the conversion module on the same layer, and the center of gravity region is a region centered on the center of gravity of the support member in a planar view.

3. The power conversion device according to claim 2, wherein the support member is a cooling plate having a flow path through which a cooling fluid flows and capable of cooling the electronic components.

4. A power conversion device as claimed in any one of claims 1 to 3, comprising a housing having a frame member which accommodates a plurality of said conversion modules and supports said conversion modules, said housing having a thickened portion formed around said electronic components which are relatively heavy by increasing the thickness of said frame member.

5. A power conversion device as claimed in any one of claims 1 to 3, comprising a housing having a frame member which accommodates a plurality of the conversion modules and supports the conversion modules, wherein the housing has a thickened portion formed around the electronic components which are relatively heavy, in which the thickness of the frame member in the center of gravity region is made greater than the thickness of the frame member outside the center of gravity region.

6. A power conversion device as claimed in any one of claims 1 to 3, wherein the relatively heavy electronic component in the lowest layer is a filter substrate, and the relatively heavy electronic component in the second lowest layer is a transformer.

7. A power conversion device according to any one of claims 1 to 3, wherein an inverter that controls the power supplied to the traction motor is disposed on the uppermost layer.

8. A power conversion device as described in claim 2, wherein the heaviest electronic component among the plurality of electronic components constituting the conversion module on the same layer is positioned so as to overlap the center of gravity of the support member in a planar view.

9. The power conversion device according to claim 8, wherein the plurality of electronic components are a transformer and a bulk capacitor, and the heaviest electronic component is the transformer.

10. The power conversion device according to claim 8, wherein the plurality of electronic components are a filter board and a coil module, and the heaviest electronic component is the filter board.

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