Inverter Module Assembly

Abstract

An inverter module assembly (170) for an inverter (110), the inverter module assembly (170) includes a power board (152), a driver board (157), a plurality of bus bars (153, 153A, 153B), and a capacitor and sensor board (151). The driver board (157) is configured to accommodate a plurality of transistors (158). The plurality of bus bars (153, 153A, 153B) are disposed between the power board (152) and the driver board (157), and the capacitor and current sensor board (151) is mounted in parallel to the driver board (157) and the power board (152). The power board (152) is electrically insulated, and the power board (152) is mounted to the inverter casing (110) to dissipate heat from the plurality of transistors (158).

Description

[Technical field]

[0001] The present invention relates to an inverter module assembly, and more particularly, but not exclusively, to a compact arrangement of power modules of an inverter module assembly in a motor vehicle. [Background technology]

[0002] Inverters are used to control the frequency of the power provided by the power supply to the electric motor. Without an inverter, the electric motor would run at full speed as soon as the power supply is switched on. Therefore, inverters control the speed and acceleration of the motor as per the requirement. Furthermore, inverters invert the direct current (DC) provided by the power supply to alternating current (AC).

[0003] In electric / hybrid vehicles, the components of the electric drivetrain, such as controller(s), inverter(s), power module(s), electric board(s), etc., are prone to heat up and may fail after certain usage cycles. Sometimes, the continuous heat up may result in fire or sparks in the electric drivetrain. Therefore, it is necessary to effectively dissipate the heat generated in the electric components, especially the inverter, which is a critical component of the electric drivetrain.

[0004] Also, the inverter is mounted on the swing arm of the two-wheeled vehicle. In such a scenario, the inverter is easily exposed to water due to the low ground clearance. Water seepage in the inverter module may also lead to failure of the electrical system. Therefore, the inverter module needs to meet the desired waterproof rating. Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, in the electric drivetrain of an electric or hybrid vehicle, various electric and electronic components, including capacitors, transistors, resistors, etc., are used as part of controllers, inverters, DC-DC converters, etc. These electric components are typically mounted and soldered onto a printed circuit board (PCB). Mounting these components on a PCB can crowd them together, making them difficult to troubleshoot, maintain, and replace. However, such problems can be avoided if the electronic components are spaced apart, but in such cases, the subsystems of the electric drivetrain can be large in size and difficult to accommodate within a compact space. In two-wheeled vehicles, mounting the electric drivetrain is a problem due to limited vehicle space and the particular vehicle layout. Therefore, there is a need to optimally secure the electric and electronic components to allow access for troubleshooting, servicing, maintenance, and replacement without making the electric and electronic assemblies unnecessarily bulky, cumbersome, and large in size.

[0006] Also, with the increase in rated specifications of the electrical and electronic components, such as maximum voltage specifications, operating frequency bands, etc., there is an increase in heat from the electrical and electronic components. Therefore, thermal management of the heat emitted by the electrical and electronic components soldered and mounted on the PCB is an unsolved problem by conventional inverters. When components are located in close proximity to each other, there is a high possibility of heat transfer from one component to another, resulting in an increase in temperature of the PCB. Also, components may not function above their rated temperature, electrical connections on the PCB may fail, and the PCB may structurally deform at higher temperatures. Components may ignite and cause fires, leading to failure of the electric drivetrain as well as the vehicle employing the electric drivetrain. Thus, poor thermal management in conventional inverter assemblies poses a potential safety risk.

[0007] According to known techniques, electronic assemblies such as inverters, converters, power boards, controllers, etc. in an electric drivetrain are spaced apart to prevent the spread of fire, however, this compromises the compactness of the electric drivetrain and may not extract enough heat from the individual components to reduce the possibility of rapid temperature rises in those components and PCBs in a fail-safe manner.

[0008] In another known technique, forced cooling mechanisms are provided in electric drive trains by disposing a heat exchange member in thermal contact with the casing of the electronic product. However, the heat emitted from the electrical and electronic components on the PCB is not properly managed. In another known technique, liquid cooling mechanisms are employed for the thermal management of electronic assemblies. The entire electronic product or electronic assembly may be immersed in liquid coolant. However, the liquid coolant stagnates and the effectiveness of cooling the electronic assembly is significantly reduced. In the case of forced liquid cooling, the liquid coolant is required to reach the individual electrical and electronic components. Such a system may significantly increase the cost and make the electronic assembly more complex rather than simple. Furthermore, the coolant may not reach all the hot zones. Thus, there is a need to cool the electronic assembly without complicating or increasing the cost of the electronic assembly.

[0009] Thus, there is a need for improved electrical and electronic assemblies, particularly inverters, where the assembly of electronic components is optimally sized, lightweight, and thermally managed without increasing cost, and further where maintenance and servicing is unintrusive and uncomplicated. [Means for solving the problem]

[0010] The detailed description will now be made with reference to the accompanying drawings, in which like numerals are used to refer to like features and components throughout.

[0011] In one embodiment of the present invention, an inverter module assembly is disclosed that is comprised of a power supply board, a driver board, a capacitor and current sensor board, and a number of bus bars. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 illustrates a side view of an exemplary embodiment of an electric motor assembly. [Diagram 2] FIG. 2 is a top perspective view of an inverter and an inverter casing. [Diagram 3] FIG. 2 is a perspective view of an inverter module assembly. [Figure 4] FIG. 2 is an exploded view of the first power module. [Diagram 5] FIG. 2 is a side cross-sectional view of the first power module. [Figure 6] FIG. [Figure 7] FIG. 2 is a side cross-sectional view of the inverter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In one embodiment of the present invention, an inverter module assembly is disclosed, which is composed of a power board, a driver board, a capacitor and current sensor board, and a number of bus bars. The power board is configured to accommodate a number of transistors and other electronic components. The driver board acts as a control unit for the transistors mounted on the power board. The power board, the driver board, and the capacitor and current sensor board are mounted parallel to each other. Also, a number of bus bars are disposed between the power board and the capacitor and current sensor board. The parallel arrangement as described above ensures proper spacing between all electrical and electronic components, as well as compact packaging.

[0014] In one embodiment, the power board is an insulated metal substrate (IMS) board, which ensures that the heat emitted by the electrical and electronic components is absorbed by the power board while ensuring that the power board is electrically insulated. Furthermore, the power board and the driver board are mounted in an inverter casing which ensures that the power board is cooled, and the driver board and the electrical and electronic components mounted in the inverter casing are cooled through a thermal management system adopted in the inverter casing. The present invention and any attendant embodiments and their other advantages will be described in more detail in the following paragraphs together with the figures. It should be noted that the description and figures are merely illustrative of the principles of the present invention. Although not explicitly described or shown herein, various arrangements incorporating the principles of the present invention are conceivable. Furthermore, any statements herein referring to the principles, aspects, and examples of the present invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0015] FIG. 1 illustrates a side view of an exemplary embodiment of an electric motor assembly. As in FIG. 1, an electric motor assembly (100) is provided. The electric motor assembly (100) includes an electric motor (105), a motor casing (121), a motor shaft (115), an inverter (110), and an inverter casing (111). The motor shaft (115) is disposed in a vertical plane forming a motor shaft axis (A-A'). The motor casing (121) circumferentially surrounds the electric motor (105) along the motor shaft axis (A-A'). The inverter casing (111) circumferentially covers the inverter (110) along the motor shaft axis (A-A'). The motor casing (121) and the inverter casing (111) are mechanically connected to each other, thereby providing compact packaging of the motor and the inverter. According to one embodiment, the motor casing (121) and the inverter casing (111) have a number of fins (120, 125) on the outer surfaces of the motor casing (121) and the inverter casing (111). The number of fins provides air cooling for the inverter (110) and the electric motor (105).

[0016] According to one embodiment, the plurality of concentric fins (120) on the motor casing (121) are concentric along the motor shaft axis AA'. The concentric fins (120) are disposed at a predetermined distance from each other on the outer surface of the motor casing (121). Further, plate fins (125) are disposed circumferentially on the outer surface of the inverter casing (111).

[0017] 2 illustrates a top perspective view of the inverter (110) and the inverter casing (111). The inverter casing (111) covers the inverter (110). The inverter (110) includes a controller (145) and a power splitter (130). The power splitter (130) includes an anode (135), a cathode (140), a support plate (165), and an insulating member (132). The power splitter (130) distributes power to a plurality of power modules (150, 155, 160). The plurality of power modules (150, 155, 160) includes a first power module (150), a second power module (155), and a third power module (160).

[0018] According to one embodiment, the inverter casing (111) is connected to the electric motor casing (121) by a number of connection means (not labeled), including a number of fasteners.

[0019] 3 illustrates a perspective view of an inverter module assembly (170). According to the illustrated embodiment, the inverter module assembly (170) includes a power splitter (130) and a first power module (150). The first power module (150) includes a power supply board (152), a driver board (157), and a capacitor and current sensor board (151). The power supply board (152), the driver board (157), and the capacitor and current sensor board (151) are arranged parallel to each other. The capacitor and current sensor board (151) is arranged on the top, and the power supply board (152) forms a base. The driver board (157) is arranged between the capacitor and current sensor board (151) and the power supply board (152).

[0020] According to a preferred embodiment, the power board (152) is an insulated metal substrate (IMS) board. The insulated metal substrate (IMS) board has at least three layers, whereby a top layer receives heat from components disposed on the top surface of the IMS-based power board (152). According to a preferred embodiment, a plurality of transistors and other electronic components are mounted on the top surface of the IMS board. According to a preferred embodiment, the top layer of the IMS-based power board (152) is made of copper foil. Furthermore, a second layer of the IMS-based power board (152) below the first layer is an insulating layer that makes it possible to prevent electrical charging of the IMS-based power board (152). The insulating layer is generally made of a polymer or ceramic, which ensures that the power board (152) is electrically insulated while the power board (152) is thermally conductive. A third layer below the second layer is a carrier layer. Generally, the carrier is made of aluminum. According to one embodiment, the base of the power board 152 is mounted to the inverter casing 110. This mounting of the power board 152 to the inverter casing 110 thereby ensures that the power board 152 is cooled directly from a cooling mechanism implemented on the inverter casing 110. According to a preferred embodiment, the inverter casing 110 is air-cooled through a number of fins.

[0021] FIG. 4 illustrates an exploded perspective view of the power module (150) as an example. The first power module (150) further includes a plurality of bus bars (153, 153A, 153B) disposed between the power supply board (152) and the driver board (157). The plurality of bus bars (153, 153A, 153B) includes a first bus bar (153), a second bus bar (153A), and a third bus bar (153B). The first bus bar (153) and the third bus bar (153B) respectively act as a DC+ bus bar and a DC- bus bar that receive DC current from the power splitter (130). Furthermore, the second bus bar (153A) acts as a phase bus bar for transmitting inverter AC current. The multiple bus bars (153, 153A, 153B) are disposed parallel to one another such that the second bus bar (153A) is disposed between the first bus bar (153) and the third bus bar (153B). The multiple bus bars (153, 153A, 153B) also provide mounting support for the capacitor and current sensor board (151), the driver board (157) and the power board (152), such that the capacitor and current sensor board (151) and the driver board (157) are fixed to the power board (152), and the fixing parts connecting the capacitor and current sensor board (151), the driver board (157) and the power board (152) pass through the multiple bus bars (153, 153A, 153B). In one embodiment, the bus bars (153, 153A, 153B) are provided with through holes that allow the fasteners to pass through the bus bars (153, 153A, 153B). In one embodiment, the through holes of the bus bars (153, 153A, 153B) are provided with a synthetic fiber coating. In one embodiment, the second bus bar (153A) is sandwiched between the driver board (157) and the power board (152).

[0022] The capacitor and current sensor board (151) includes a plurality of capacitors (154) and a plurality of current sensors mounted on the top surface of the capacitor and current sensor board (151). The capacitor and current sensor board (151) is also provided with a phase terminal joint (149), through which an angled phase terminal (156) is disposed. The angled phase terminal (156) passes through the capacitor and current sensor board (151) and the driver board (157) and is connected to a second bus bar (153A). The second bus bar (153A) routes the phase current to the angled phase terminal (156), which is then routed to the electric motor (105). The power supply board (152) is also provided with a plurality of standoff spacers (158) to ensure spacing between the driver board (157) and the power supply board (152).

[0023] 5 illustrates a side cross-sectional view of the first power module (150). According to the illustrated embodiment, a first bus bar (153) provides a connection between the capacitor and current sensor board (151) and the power supply board (152). Also, an angled phase terminal (156) passes through the capacitor and current sensor board (151) and the driver board (157) and is connected to a second bus bar (153A).

[0024] FIG. 6 illustrates a top cross-sectional view of an inverter (110) having three power modules (150, 155, 160) disposed on three different sides of the inverter (110) covered by an inverter casing (111). According to one embodiment, the first power module (150) faces the third power module (160). Also, the second power module (155) is disposed adjacent to the first power module (150) and the third power module (160). The first power module (150) is disposed at a first predetermined gap from the third power module (160). Furthermore, the first power module (150) is disposed at a second predetermined gap from the second power module (155). The third power module (160) also forms a third predetermined gap between the second power module (155) and the third power module (160). The first predetermined gap, the second predetermined gap, and the third predetermined gap ensure that the power modules (150, 155, 160) are spaced apart from one another in such a manner that heat generated by any one of the power modules (150, 155, 160) does not affect the operation of the other power modules from the power modules (150, 155, 160). The separation of the power modules (150, 155, 160) also ensures that each of the power modules (150, 155, 160) is properly cooled through the air-cooled plate fins (125) provided on the inverter casing (111).

[0025] 7 illustrates a partial cross-sectional perspective view of the inverter (110). The inverter casing (110) is provided with plate fins (125) circumferentially on the outer surface of the inverter casing (111). According to the illustrated embodiment, a plurality of external fixing parts (159) are provided to fix the driver board (157) to the inverter casing (110). In another embodiment, the plurality of external fixing parts (159) allow fixing of the power board (152) to the inverter casing (110).

[0026] Specifically, the aspect of the axial integration of the electric motor and the inverter makes the integrated electric motor assembly modular and compact, resulting in minimal or negligible voltage drop between the components during the period of current flow while providing a technical solution to a technical problem. Also, due to the compact layout of the inverter on the electric motor, the overhang of the inverter in the vehicle is reduced, thereby eliminating the additional components required to support the integrated electric motor-inverter assembly. Furthermore, the control board is mounted on the power splitter, thereby reducing the additional space requirement for packaging of the control board in the vehicle. Also, a plurality of fin members are provided on the outer surface of the integrated electric motor assembly, which ensures heat dissipation due to the surrounding air flow, thus reducing the need for a separate cooling system. Therefore, the number of components in the vehicle is reduced, thereby reducing the vehicle's weight and, as a result, improving the vehicle's performance.

[0027] Improvements and modifications may be incorporated herein without departing from the scope of the invention. [Explanation of symbols]

[0028] 100 Electric motor assembly 105 Electric Motor 110 Inverter 111 Inverter casing 115 Motor shaft 120 Concentric Fins 121 Motor casing 125 Plate Fin 130 Power Splitter 132 Insulating materials 135 Anode 140 Cathode 145 Controller 149 phase terminal junction 150 First Power Module 151 Capacitor and Current Sensor Board 152 Power Board 153 First busbar 153A 2nd busbar 153B 3rd busbar 154 Capacitor 155 Second Power Module 156 Angled phase terminal 157 Driver Board 158 Spacer 159 External fixing part 160 3rd Power Module 165 Support plate 170 Inverter module assembly

Claims

1. A power module (150, 155, 160) of an inverter (110), said power module (150, 155, 160) comprising: a power board (152) configured to house a plurality of transistors; a driver board (157) mounted parallel to the power supply board (152); a capacitor and current sensor board (151) mounted in parallel to the driver board (157) and the power supply board (152); a plurality of bus bars (153, 153A, 153B) disposed between the power supply board (152) and the capacitor and current sensor board (151); Equipped with the plurality of bus bars (153, 153A, 153B) include a first bus bar (153), a second bus bar (153B), and a third bus bar (153); The power supply board (152) is electrically isolated, The power supply board (152) is mounted on an inverter casing (111) to dissipate heat from the plurality of transistors, the capacitor and current sensor board (151) is configured to have a phase terminal junction (149), and an angled phase terminal (156) is configured to pass through the phase terminal junction (149), and the angled phase terminal (156) passes through the driver board (157) to connect the second bus bar (153A).

2. The power module (150, 155, 160) of claim 1, wherein the power supply board (152) is an insulated metal substrate (IMS) board.

3. The power module (150, 155, 160) of claim 1, wherein the second bus bar (153A) is disposed between the first bus bar (153) and the third bus bar (153B).

4. A power module (150, 155, 160) as described in claim 1, wherein the first busbar (153) and the third busbar (153B) are configured to receive direct current (DC) from the inverter (110), and the second busbar (153A) is configured as a phase busbar for transmitting phase current to angled phase terminals (156).

5. The power module (150, 155, 160) of claim 1, wherein the second bus bar (153A) is sandwiched between the driver board (157) and the power supply board (152).

6. 2. The power module (150, 155, 160) of claim 1, wherein the capacitor and current sensor board (151) and the driver board (157) are fixed to the power supply board (152), and the fixation is through the plurality of bus bars (153, 153A, 153B).

7. 2. The power module (150, 155, 160) of claim 1, wherein the bus bars (153, 153A, 153B) have a plurality of through holes, the through holes being covered with synthetic fiber to allow mechanical connection between the capacitor and current sensor (151), the driver board (157), and the power supply board (152).

8. A power module (150, 155, 160) as described in claim 1, wherein the inverter module assembly (170) is mounted on the inverter casing (111) through a plurality of external fixing parts (159), the plurality of external fixing parts (159) are fixed to the underside of the power board (152), the upper side of the power board (152) is capable of accommodating the plurality of transistors and one or more power devices, and the upper side of the power board (152) is opposite the underside of the power board (152).

9. 2. The power module (150, 155, 160) of claim 1, wherein the power supply board (152) is provided with a plurality of standoff spacers (158) for enabling spacing between the driver board (157) and the power supply board (152).

10. 2. The power module (150, 155, 160) of claim 1, wherein the driver board (157) is fixed to the inverter casing (111) through a plurality of external fixing parts (159), and the plurality of external fixing parts (159) are fixed to the driver board (157) through the power supply board (152) and the plurality of bus bars (153, 153A, 153B).

11. 2. The power module of claim 1, wherein the inverter includes an inverter module including a controller, a power splitter, and the power splitter has an anode, a cathode, and an insulating member.

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