Claims:We Claim

1.
A power module (150, 155, 160) of an inverter (110), said power module (150, 155, 160) comprising:
a power board (152) being configured to accommodate a plurality of transistors (158);
a driver board (157) being mounted parallel to said power board (152);
a capacitor and current sensor board (151) being parallelly mounted to said driver board (157) and said power board (152); and
a plurality of busbars (153, 153A, 153B) being disposed between said power board (152) and said capacitor and current sensor board (151); and
wherein,
said power board (152) being electrically isolated, and
said power board (152) being mounted to an inverter casing (110), to dissipate heat from plurality of transistors (158).
2. The power module (150, 155, 160) as claimed in claim 1, wherein said power board (158) being an insulated metal substrate (IMS) board.
3. The power module (150, 155, 160) as claimed in claim 1, wherein said plurality of busbars (153, 153A, 153B) include a first busbar (153), a second busbar (153B) and a third busbar (153A) wherein said second busbar (153A) being disposed between said first busbar (153) and said third busbar (153B).
4. The power module (150, 155, 160) as claimed in claim 3, wherein said first busbar (153) and said third busbar (153B) being configured for receiving a direct current (DC) from said invertor (110) and said second busbar (153A) being configured as a phase busbar for transmitting a phased current to an angled phase terminal (156).
5. The power module (150, 155, 160) as claimed in claim 3, wherein said second busbar (153A) being sandwiched between said driver board (157) and said power board (152).
6. The power module (150, 155, 160) as claimed in claim 1, wherein said capacitor and current sensor board (151) and said driver board (157) being fastened to said power board (152), said fastening being through said plurality of busbars (153, 153A, 153B).
7. The power module (150, 155, 160 as claimed in claim 1, wherein said plurality of busbars (153, 153A, 153B) being provided with a plurality of through holes (not labelled), said plurality of through holes being covered with synthetic fibre for permitting a mechanical connection between said capacitor and current sensor board (151), said driver board (157) and said power board (152).
8. The power module (150, 155, 160 as claimed in claim 1, wherein said capacitor and current sensor board (151) being configured to have a phase terminal junction (149) wherein an angled phase terminal (156) being configured to pass through said phase terminal junction (149); wherein said angled phased terminal (156) passing through said driver board (157) for connectting said second busbar (153A).
9. The power module (150, 155, 160) as claimed in claim 1, wherein said inverter module assembly (170) being mounted to said inverter casing (110) through a plurality of external fasteners (159); wherein said the plurality of external fasteners (159) being fastened to a lower face of said power board (152); and wherein an upper face of said power board (152) being capable of accommodating said plurality of transistors (158) and one or more power devices, wherein said upper face of said power board (152) being opposite to said lower face of said power board (152).
10. The power module (150, 155, 160) as claimed in claim 1, wherein said power board (152) being provided with a plurality of standoff spacers (158) to enabling a spacing between said driver board (157) and said power board (152).
11. The power module (150, 155, 160) as claimed in claim 1, wherein said driver board (157) being fastened to said inverter casing (110) through plurality of external fasteners (159), wherein said plurality of external fasteners (159) being fastened to said driver board (157) through said power board (152) and said plurality of busbars (153, 153A, 153B).
12. The power module (150, 155, 160) as claimed in claim 1, wherein said invertor (110) including a invertor module (170), said invertor module (170) includes a controller (145), a power splitter (130), said power splitter (130) having an anode (135), a cathode (140) and an insulation member (132). , Description:TECHNICAL FIELD
[0001] The present subject matter relates to an inverter module assembly. More particularly and not exclusively, it pertains to compact configuration of power modules of the inverter module assembly in an automobile.

BACKGROUND
[0002] An inverter is used to control the frequency of power supplied by the power source to an electric motor. Without the inverter, the electric motor would operate at full speed as soon as the power supply is turned ON. Therefore, the inverter controls the speed and acceleration of the motor as per the requirement. Further, the inverter inverts the direct current (DC) supplied by the power source to alternating current (AC).
[0003] In electric/hybrid vehicles, parts of an electric drive train, such as, one or more controllers, one or more inverters, one or more power modules, one or more electrical boards etc., tend to get heated up and may fail to function after a certain number of use cycles. Sometimes, the continuous heating up may result into fire or sparking in the electric drive train. Thus, there is a need to effectively dissipate the heat generated in the electrical parts especially the inverter which is the key component of the electric drive train.
[0004] Additionally, an inverter is mounted to a swing arm of a two wheeled vehicle. In such a scenario, the inverter is prone to water exposure due to low ground clearance. Seepage of water in the inverter modules may also lead to failure of electrical system. Therefore, the inverter modules need to meet a desired waterproofing rating.

BRIEF DESCRIPTION OF DRAWINGS
[0005] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0006] Figs. 1 illustrates a side view of an exemplary embodiment of an electric motor assembly.
[0007] Fig. 2 illustrates a top perspective view an inverter and an inverter casing.
[0008] Fig. 3 illustrates a perspective view of an inverter module assembly.
[0009] Fig. 4 illustrates an exploded view of a first power module.
[0010] Fig. 5 illustrates a side section view of a first power module.
[0011] Fig. 6 illustrates a top section view of the inverter.
[0012] Fig. 7 illustrates a side section view of the inverter.

DETAILED DESCRIPTION OF THE INVENTION
[0013] Conventionally, in an electric drive train of an electric or a hybrid vehicle, various electrical and electronic parts including capacitors, transistors, resistors etc. are used as part of controllers, inverters, DC-DC converters, etc. These electrical parts are usually mounted and soldered to a Printed circuit board (PCB). The mounting of these components on the PCB may make them congested and difficult for troubleshooting, maintenance and replacement. However, if the electronic components are distantly spaced, such problem may be avoided but, in such cases, the sub-systems of the electric drive train may become large in size and difficult to be accommodated in a compact space. In two wheeled vehicles, the mounting of electric drive train is a problem due to limited vehicle space and specific vehicle layout. Thus, there is a need to optimally secure the electrical and electronic components to enable access for troubleshooting, servicing, maintenance and replacement without making the electrical and electronic assembly undesirably bulky, clumsy or large in size.
[0014] Also, with increased rating specifications of the electrical and electronic components, such as, maximum voltage specification, frequency band of operation, it results in increase in heat from the electrical and electronic components. Therefore, heat management of the heat released by the electrical and electronic components soldered and mounted on the PCB is a problem unresolved by conventional inverters. If the components are located in close proximity to each other, there are high chances of heat propagation from one component to another resulting in temperature rise of the PCB. Also, the components may fail to function beyond a rated temperature, the electrical connections on the PCB may fail, and the PCB may get structurally deformed at higher temperatures. The components may ignite and cause fire leading to failure of the electric drive train as well as the vehicle employing the electric drive train. Therefore, poor heat management in the conventional inverter assembly pose a potential safety risk.
[0015] As per known art, the electronic assemblies such as inverters, converters, power boards, controllers in the electric drive train are spaced apart to arrest propagation of fire. However, this compromise the compactness of the electric drive train. Also, sufficient heat may not be extracted from individual components to reduce the probability of drastic increase in the temperature of the components and the PCB in a failsafe manner.
[0016] In another known art, a forced cooling mechanism is provided to the electric drive train by disposing a heat exchange member in thermal contact with the casing of the electronic product. However, the heat released from the electrical and electronic components on the PCB is not adequately managed. In another known art, a liquid cooling mechanism is employed for thermal management of the electronic assembly. The electronic product or the electronic assembly as a whole may be immersed in a liquid coolant. However, the liquid coolant is stagnant and efficacy of the cooling of the electronic assembly is substantially less. In case of forced liquid cooling, the liquid coolant is required to reach individual electrical and electronic components. Such systems may significantly increase the cost and make the electronic assembly more complex and not frugal. Further, the coolant may not reach to all hot zones. Therefore, there is exists a need for cooling the electronic assembly without making it complex or increasing the cost.
[0017] Hence, there exists a need for an improved electrical and electronic assembly, particularly for an inverter in which the assembly of the electronic components is optimal in size, light in weight and thermally managed without increasing the cost. Further, the maintenance and servicing is not cumbersome or complex.
[0018] In an embodiment of the present invention, an inverter module assembly is disclosed which is comprising of a power board, a driver board, a capacitor and current sensor board and a plurality of busbars. The power board is configured to accommodate plurality of transistors and other electronic components. The driver board act 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 plurality of busbars are disposed between the power board and the capacitor and current sensor board. The abovementioned parallel arrangement ensures adequate spacing between all the electrical and electronic components and also a compact packaging.
[0019] In an embodiment, the power board is an insulated metal substrate (IMS) board which ensures that the heat released by electrical and electronic components is absorbed by the power board while ensuring that power board is electrically isolated. Further, the power board and the driver board are mounted to the inverter casing which ensures cooling of the power board, the driver board and electrical and electronic components mounted thereof are cooled through the heat management system employed on the inverter casing. The present invention along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs. It should be noted that description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0020] Figs. 1 illustrates a side view of an exemplary embodiment of an electric motor assembly. As per 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 on a vertical plane forming a motor shaft axis (A-A’). The motor casing (121) encloses the electric motor (105) circumferentially 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 a compact packaging of the motor and the inverter. As per an embodiment, the motor casing (121) and the inverter casing (111) are having a plurality fins (120, 125) on the outer surface of the motor casing (121) and the inverter casing (111). The plurality of fins provide air cooling of the inverter (110) and the electric motor (105).
[0021] As per an 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 are (125) are disposed on the outer surface of the inverter casing (111) circumferentially.
[0022] Fig. 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 insulation member (132). The power splitter (130) distributes the electric 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).
[0023] As per an embodiment, the inverter casing (111) is connected to the electric motor casing (121) by means of plurality of connecting means (not labelled) which include plurality of fasteners.
[0024] Fig. 3 illustrates a perspective view of an inverter module assembly (170). As per the illustrated embodiment, the inverter module assembly (170) includes the power splitter (130) and the first power module (150). The first power module (150) includes a power board (152), a driver board (157) and a capacitor and current sensor board (151). The power board (152), the driver board (157) and the capacitor and current sensor board (151) are disposed parallel to each other. The capacitor and current sensor board (151) is disposed at the top and the power board (152) forms the base. The driver board (157) is disposed between the capacitor and current sensor board (151) and the power board (152).
[0025] As per the preferred embodiment, the power board (152) is an insulated metal substrate (IMS) board. The insulated metal substrate (IMS) board is having at least three layers such that the top layer receive the heat from the components disposed on the top face of the IMS based power board (152). As per the preferred embodiment, the plurality of transistors and other electronic components are mounted on the top face of the IMS board. As per a preferred embodiment, the top layer of the IMS based power board (152) is made of copper foil. Further, the second layer of the IMS based power board (152) beneath the first layer is an insulation layer which enables preventing electrical charging of the IMS based power board (152). The insulation layer is generally made of polymer or a ceramic which ensures that while the power board (152) is thermally conductive, the power board (152) is electrically isolated. The third layer beneath the second layer is a carrier layer. Generally, the carrier is made of aluminium. As per an 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 ensuring that the power board (152) is directly cooled from the cooling mechanism implemented on the inverter casing (110). As per the preferred embodiment, the inverter casing (110) is air cooled through plurality of fins.
[0026] Fig. 4 exemplarily illustrates an exploded perspective view of the power module (150). Further, the first power module (150) includes a plurality of busbars (153, 153A, 153B) disposed between the power board (152) and the driver board (157). The plurality of busbars (153, 153A, 153B) include a first busbar (153), a second busbar (153A) and a third busbar (153B). The first busbar (153) and the third busbar (153B) act as DC+ and DC- busbar respectively which receives the DC current from the power splitter (130). Further the second busbar (153A) act as a phase busbar to carry the inverter AC current. The plurality of busbars (153, 153A, 153B) are disposed parallel to each other such that the second busbar (153A) is disposed between the first busbar (153) and the third busbar (153B). The plurality of busbars (153, 153A, 153B) also provide mounting support to 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 fastened to the power board (152) and the fasteners connecting the capacitor and current sensor board (151), the driver board (157) and the power board (152) pass through the plurality of busbars (153, 153A, 153B). In an embodiment, the plurality of busbars (153, 153A, 153B) are provided with through holes which permit plurality of fasteners to pass through the plurality of busbars (153, 153A, 153B). In an embodiment, the through holes on the plurality of busbars (153, 153A, 153B) are provided with a covering of synthetic fibre. In an embodiment, the second busbar (153A) is sandwiched between the driver board (157) and the power board (152).
[0027] The capacitor and current sensor board (151) comprises a plurality of capacitors (154) and a plurality of current sensors mounted on the top face of the capacitor and current sensor board (151). The capacitor and current sensor board (151) is also provided a phase terminal junction (149) ) wherein an angled phase terminal (156) is disposed through the phase terminal junction (149). The angled phased terminal (156) passes through the capacitor and current sensor board (151) and the driver board (157) to connect with the second busbar (153A). The second busbar (153A) transmits the phased current to the angled phased terminal (156) which is then transmitted to the electric motor (105). Additionally, the power board (152) is provided with a plurality of standoff spacers (158) to ensure a spacing between the driver board (157) and the power board (152).
[0028] Fig. 5 illustrates a side section view of a first power module (150). As per the illustrated embodiment, the first busbar (153) provides a connection between the capacitor and current sensor board (151) and the power board (152). Also, the angled phased terminal (156) passes through the capacitor and current sensor board (151) and the driver board (157) to connect with the second busbar (153A).
[0029] Fig. 6 illustrates a top sectional view of the inverter (110) having three power modules (150, 155, 160) disposed on three different sides of the inverter (110) which is covered by the inverter casing (111). As per an embodiment, the first power module (150) is facing opposite to 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). Further, the first power module (150) is disposed at a second predetermined gap from the second power module (155). Also, the third power module (160) 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 ensures that the plurality of power modules (150, 155, 160) are spaced from each other in a manner that heat generated by any one of the plurality of power modules (150, 155, 160) does not impact the operation of other power modules from the plurality of power modules (150, 155, 160). Also, separation of the plurality of power modules (150, 155, 160) ensures that each of the plurality of power modules (150, 155, 160) are cooled adequately through the air cooling plate fins (125) being provided on the inverter casing (111).
[0030] Fig 7 illustrates a partial sectional perspective view of the inverter (110). The inverter casing (110) is provided with the plate fins (125) circumferentially on the outer surface of the inverter casing (111). As per the illustrated embodiment, a plurality of external fasteners (159) are provided which fastens the driver board (157) to the inverter casing (110). In another embodiment, the plurality of external fasteners (159) allow fastening of the power board (152) to the inverter casing (110).
[0031] Specifically, the aspects of axial integration of the inverter with the electric motor, makes the integrated electric motor- assembly modular and compact with minimal or negligible voltage drop across components during current flow, while providing technical solution to the technical problem. Also, due to compact layout of the inverter on the electric motor, the overhang of inverter in the vehicle is reduced, thereby eliminating additional parts required for supporting the integrated electric motor- inverter assembly. Moreover, the controlling boards are mounted over the power splitter, thereby mitigating requirement of additional space for the packaging of the controlling boards in the vehicle. Additionally, plurality of fin members are provided on the outer surface of the integrated electric motor- assembly which ensure heat dissipation due to flow of ambient air and thus mitigating the need for a separate cooling system. As such, the number of components in the vehicle is reduced, thereby making the vehicle lighter and consequently, improving performance of the vehicle.
[0032] Improvements and modifications may be incorporated herein without deviating from the scope of the invention.

LIST OF REFERENCE NUMERALS

100: Electric motor assembly
105: Electric motor
110: Inverter
111: Inverter Casing
115: Motor Shaft
120: Concentric Fins
121: Motor casing
125: Plate Fins
130: Power Splitter
132: Insulation Member
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: Second Busbar
153B: Third Busbar
154: Capacitors
155: Second Power Module
156: Angled Phase Terminal
157: Driver Board
158: Spacers
159: External Fasteners
160: Third Power Module
165: Support Plate
170: Inverter Module Assembly