EP4500674A1

EP4500674A1 - An electric motor assembly

Info

Publication number: EP4500674A1
Application number: EP23778679.3A
Authority: EP
Inventors: George Godwin; Subbiah Senthilnathan
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2022-03-27
Filing date: 2023-01-13
Publication date: 2025-02-05
Also published as: EP4500674A4; CN119183632A; WO2023187802A1

Abstract

An electric motor assembly (100) is disclosed. The electric motor assembly (100), comprising: an electric motor (105), a motor casing (121) and an inverter (110). The electric motor (105) being configured to convert electrical energy to mechanical energy. The motor casing (121), circumferentially covers said electric motor along a motor shaft axis (A-A'). The inverter (110) being electrically connected to said electric motor (105) wherein, an inverter casing (111) circumferentially covers said inverter (110) along said motor shaft axis (A-A'), and said inverter casing (111) being mechanically connected to said motor casing (121).

Description

AN ELECTRIC MOTOR ASSEMBLY

TECHNICAL FIELD

[0001] The present subject matter relates to an electric motor assembly. More particularly, an electric motor assembly for an automobile.

BACKGROUND

[0002] An electric motor is an electric machine that converts electrical energy into mechanical energy. Generally, the electric motor operates through an interaction between the motor’s magnetic field and an electric current transmitted through a winding to generate a force in the form of a torque applied on the motor’s shaft.

[0003] The electrical energy can be supplied to the electric motor from variety of sources including a direct current (DC) source such as a battery or a rectifier. Alternatively, the electric motor can be powered by an alternating current (AC) source such as a power grid, inverter or electrical generators. In case of automobiles, the electric motor is majorly powered through a DC power source such as a battery. Typically, an inverter is used to control the frequency of power supplied by the power source to the 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.

BRIEF DESCRIPTION OF DRAWINGS

[0004] 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.

[0005] Figs. 1 illustrates a side view of an exemplary embodiment of an electric motor assembly.

[0006] Fig. 2 illustrates atop perspective view an inverter and an inverter casing. [0007] Fig. 3 illustrates an exploded view of a power splitter used in the inverter. [0008] Fig. 4 illustrates a perspective view of a power module and the power splitter used in the inverter. [0009] Fig. 5 illustrates atop section view of the inverter.

[0010] Fig. 6 illustrates a bottom perspective view of the inverter and the inverter casing.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Conventionally, the inverter and the electric motor are housed separately in an automobile and electrically connected via a plurality of electrical connections. As a result, a separate inverter and a separate electric motor housing has to be accommodated in the vehicle layout. Another challenge pertains to electrical capacity and physical weight contribution of the electric motor and the inverter, particularly for a two wheeled or a three wheeled vehicle where heavy electrical components are difficult and cumbersome to fit in the compact vehicle layout space. [0012] As per known electric motors and inverters, there have been attempts to integrate the electric motor and the inverter. In the known designs, elements of the inverter are fitted on the upper portion of the motor. However, such a design leads to increase in length between output terminals of the power drivers of the inverter and the input terminals of coils of the motor. This further leads to use of more electrical wirings which also result in increase heat loss caused by an increased electric resistance possessed by the wiring. Additionally, the elongated wiring may result in fitment and noise related problems.

[0013] As per other known electric motors, the electric motor and the inverter are integrated together and cooling passages are provided in the stator of the motor and the power driver of the inverter, which are then connected through a U-shaped pipe. However, to achieve proper cooling of the electric motor and the inverter, the cooling system needs to be large or bulky in size.

[0014] As per other known electric motors, a plurality of stator cores of the electric motor are arranged about the rotation axis at evenly spaced intervals to constitute a cylindrical stator structure and a plurality of cooling passages are formed in the stator cores. The inverter which converts the DC current to AC current include plurality of power drivers which are arranged on the stator cores respectively. [0015] As per other known electric motors and inverters, the inverter is attached on a side wall of the electric motor to minimize the wiring length. However, such a motor does not support high capacity inverters which produce high amount of heat. [0016] The objective of the present invention is to integrate the electric motor and the inverter such that the power modules of the inverter which invert the power supply from DC to AC current are adequately cooled. Further, disadvantages of long high voltage wirings, compact fitment, safe assembly and disassembly of the inverter and the motor are resolved. Further, the motor and the inverter as per an additional objective of the present invention should not suffer heat damage or short circuit and should not incur high cost or much weight.

[0017] Therefore, the present subject matter discloses an improved electric motor assembly having an electric motor, a motor casing, an inverter and an inverter casing. The motor casing circumferentially covers the electric motor along a motor shaft axis and the inverter casing circumferentially covers the inverter along the motor shaft axis. The inverter casing is mechanically connected to the motor casing. The circumferential casing of the motor and inverter ensures a compact packaging of the motor and inverter such that the motor and the inverter are packaged in an integrated manner and also motor and the inverter are connected together in a shortest distance which eliminates the necessity of elongated wirings. Thereby heat loss during electrical connection between the motor and the inverter are reduced. Additionally, a circumferential casing ensures that no separate casing is required for the inverter and the motor. In an embodiment, same size and same shape circumferential casing are used for both the electrical motor and the inverter which reduces the cost of the electric motor assembly having an integrated motor and inverter significantly.

[0018] In another aspect of the present subject matter, the inverter include a power splitter, plurality of power modules, one or more controllers and plurality of phase connectors. The plurality of power modules include a first power module, a second power module and a third power module. The plurality of power modules are connected to the power splitter and the controller. The controller controls the power inversion and the power modules distribute the function of power inversion in separate modules corresponding to the phase of the motor. In an embodiment, a three phase motor is integrated with an inverter having a three power modules. As a result, the power modules efficiently act upon the signal assigned by the controller. Further, each power module is separated from other power modules at a pre-determined distance which ensures the heat produced by each of the power module does not impact the other power modules.

[0019] In another aspect of the present invention, the DC power from the inverter is distributed to the different power modules of the power distribution system through a power splitter. The power splitter ensures that power distributed to each of the power module is distributed as per the capacity of the power module.

[0020] In another aspect of the present invention, the power transmission from the inverter to the electric motor is achieved through plurality of phase connectors which ensures a terminal connection between the inverter and the motor eliminating the heat dissipation caused by elongated wires or complicated layouts in the known designs. The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate the 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.

[0021] Fig. 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 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 of fins (120, 125) on the outer surface of the motor casing (121) and the inverter casing (111). The plurality of fins (120, 125) provides air cooling of the inverter (110) and the electric motor (105).

[0022] As per an embodiment, the plurality of fins (120) on the motor casing (121) are concentric along the motor shaft axis. 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. The inverter is electrically connected to a power supply of an appliance, such as, a vehicle, The inverter does inversion and regulation of the power supply and supplies inverter power supply to the motor to drive the motor. The motor may then drive the appliance, such as the vehicle. In an embodiment, the motor is a three 3 phase AC motor and the Power supply is DC power supply from one or more batteries. The inverter converts the DC supply to AC supply and the AC supply drives the motor. In another embodiment, the supply may be an AC supply and the inverter converts AC to DC and DC supply drives the motor. In an embodiment, the electric motor assembly may be hub mounted to the hub of the wheel of a vehicle. In another embodiment, the electric motor assembly may be mounted to frame of the vehicle at a suitable location in either lateral direction or longitudinal direction of the vehicle. The electric motor assembly is so mounted to ensure the CG of the vehicle is balanced in both lateral and longitudinal direction.

[0023] 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 plurality of power modules (150, 155, 160), a controller (145), and a power splitter (130). The power modules (150, 155, 160) are responsible for inversion of the power supply received from the battery. The controller (145) controls the operation of the power modules (150, 155, 160) and also the operation of the electric motor (105), based on various parameters of the motor, such temperature, voltage of power supply being supplied by the battery, SOC of Battery, etc., The power splitter (130) splits the power supply received from the battery to each of the power modules (150, 155, 160). In an embodiment, each power module (150, 155, 160) corresponds to a single phase of the AC power being supplied to the electric motor (105). The power splitter (130) includes an anode (135), a cathode (140), a support plate (165) laminated in an insulation member (132) as shown in Fig. 3. The power splitter (130) distributes the electric power to the 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). Each power module (150, 155, 160) has a plurality of electrical and electronic components mounted on a PCB and attached to inner surface of the inverter casing by means of a plurality of fasteners.

[0024] As per an embodiment, the inverter casing (111) is externally connected to the electric motor casing (121) by means of a plurality of connecting means which include plurality of fasteners.

[0025] Fig. 3 illustrates an exploded view of the power splitter (130) used in the inverter (110). The anode (135), the cathode (140), and the support plate (165) are laminated by the insulation member (132). The anode (135) as per a preferred embodiment has a plate and a power terminal (135’) together forming the anode (135). The anode (135) has a anode power terminal (135’) that connects to negative terminal of a battery and a plurality of electrical anode connectors 135a, 135b, and 135c that project outwards from the sides of anode plate. Each of these electrical connectors (135a, 135b, 135c) connect to a negative terminal or bus of each power module. The cathode (140) as per a preferred embodiment has a plate and a cathode power terminal (140’) together forming the cathode (140). Similarly, the cathode (140) has a power terminal (140’) that connects to the positive terminal of the battery and a plurality of electrical cathode connectors 140a, 140b, and 140c that project outwards from the sides of cathode plate. Each of these electrical connectors (140a, 140b, 140c) connect to the positive terminal or bus of each power module. The location of the electrical connectors (135a, 135b, 135c, 140a, 140b, 140c) on the anode plate and the cathode plate are configured at different heights to make the electrical connection between the connectors and the terminals of the power module (150), easily accessible, while compactly mounting the power splitter (130) in the center of the inverter. Support plate (165) supports both the cathode (140) and the anode (135) and is fastened at a plurality of vertices of the support plate (165) to an inner surface of the inverter casing. The insulation member (132) insulates the support plate (165), the anode (135) and the cathode (140) and also supports their mounting. Also visible are the slits in the insulation member (132) for the electrical connectors of each plate to extend through the insulation member.

[0026] Fig. 4 illustrates a perspective view of the inverter module assembly (170) including one of the plurality of power modules (150, 155, 160) electrically connected to the splitter (130) through a plurality of electrical connectors. As per the illustrated embodiment, the second power module (155) is electrically coupled with the power splitter (130) and receives the power from power splitter (130) for inversion. The power is transmitted from the power module (155) to the motor (105) through an angled phase terminal (156). Each of the plurality of power module (150, 155, 160) transmit sthe electrical energy to the motor (105) through a separate angled phase terminal (156). Each power module (150, 155, 160) comprises a PCB on which high voltage capacitors and transistors and rectifier bridges are mounted which dissipate more heat. These components are interconnected by means of wires or buses. The heat from these components is transmitted to the PCB and to the casing of the inverter (110) and the plater fins (125) of the inverter (110) aid in removal of the heat extracted. A wire from the phase terminal supplies a single phase AC current to the motor (105).

[0027] Fig. 5 illustrates a cross sectional view of the inverter (110) with a lid of the inverter removed. The power terminals (135’, 140’) from the power splitter (130) protrude through the lid and facilitate electrical connection of the inverter

(110) with the battery. Without the lid, the circumferentially arranged three power modules (150, 155, 160) connected to the power splitter (130) and the controller (145) are visible. The three power modules (150, 155, 160) are being 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).

[0028] Fig 6 illustrates a front perspective view of the inverter (110) and the inverter casing (111), with the motor casing unfastened from the inverter casing. The inverter casing is provided with the plate fins (125) circumferentially on the outer surface of the inverter casing (111). Further the inverter (110) is provided plurality of phase connectors (175) or wires which are configured to supply current from the inverter (110) to the electric motor (105). As per an embodiment, three independent phase connectors (175) are provided to connect to a three phase electric motor (105).

[0029] Specifically, the aspects of axial integration of the inverter (110) with the electric motor (105), makes the integrated electric motor- assembly (100) 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 (110) on the electric motor (105), the overhang of inverter (110) in the vehicle is reduced, thereby eliminating additional parts required for supporting the integrated electric motor- inverter assembly (100). Moreover, the power control boards are mounted over the current power splitter (130), thereby mitigating requirement of additional space for the control boards in the vehicle. Additionally, plurality of fin members (120, 125) are provided on the outer surface of the integrated electric motor- assembly (100) 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.

[0030]

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

135a, 135b, 135c: Anode connectors

135’: power terminal

140: Cathode

140a, 140b, 140c: Anode connectors

140’: Cathode power terminal 145: Controller

150: First Power Module

155: Second Power Module

156: Angled Phase Terminal 160: Third Power Module

165: Support Plate

170: Inverter Module Assembly

Claims

I/We claim:

1. An electric motor assembly (100), said electric motor assembly (100) comprising: an electric motor (105), being configured to convert electrical energy to mechanical energy; a motor casing (121), circumferentially covering said electric motor (105) along a motor shaft axis (A-A’); an inverter (110) electrically connected to said electric motor (105); wherein, said inverter being positioned co-axially with said electric motor; an inverter casing (111) circumferentially covering said inverter (110) along said motor shaft axis (A-A’), and said inverter casing (111) being mechanically connected to said motor casing (121).

2. The electric motor assembly (100) as claimed in claim 1, wherein said inverter (110) includes a power splitter (130), a plurality of power modules (150, 155, 160) for inverting power supply received from a power source, one or more controllers (145) and plurality of phase connectors (175).

3. The electric motor assembly (100) as claimed in claim 2, wherein said plurality of power modules (150, 155, 160) being disposed on an inner surface of said inverter casing (111), wherein, said plurality of power modules (150, 155, 160) includes: a first power module (150); a second power module (155); and a third power module (160); wherein, said plurality of power modules (150, 155, 160) being electrically connected to one ormore controllers (145), and said power splitter (130).

4. The electric motor assembly (100) as claimed in claim 3, wherein said first power module (150) being disposed opposite from said third power module (160) forming a first predetermined gap between said first power module (150) and said third power module (160).

5. The electric motor assembly (100) as claimed in claim 3, wherein said first power module (150) being disposed adjacent from said second power module (155) forming a second predetermined gap between said first power module (150) and said second power module (155), wherein, said second power module (155), being disposed adjacently from said third power module (160) forming a third predetermined gap between said second power module (155) and said third power module (160).

6. The electric motor assembly (100) as claimed in claim 3, wherein said one or more controller (145) being disposed opposite to said second power module (155) forming a fourth predetermined gap between said second power module (155) and said one or more controller (145).

7. The electric motor assembly (100) as claimed in claim 3, wherein said one or more controller being disposed on an inner surface of said inverter casing (H l).

8. The electric motor assembly (100) as claimed in claim 2, wherein said power splitter (130) being configured to receive a power from a power source and said power splitter (130) being capable of transmitting said power to each of said plurality of power modules (150, 155, 160).

9. The electric motor assembly (100) as claimed in claim 2, wherein said power splitter (130) includes an anode (135), a cathode (140), a support plate (165) and an insulation member (132), wherein, said power spliter (130), being configured to receive a direct current from a power source and spliting said direct current to said plurality of power modules (150,155,160).

10. The electric motor assembly (100) as claimed in claim 2, wherein said inverter (110) being configured to invert a direct current being received from a power source to a single phase alternating current, wherein, each of said plurality of phase connectors (175), being configured to transmit a single phase alternating current to said electric motor (105).

11. The electric motor assembly (100) as claimed in claim 1, wherein an said inverter casing (111), having a plurality of fins (125) on an outer surface of said inverter casing (111).

12. The electric motor assembly (100) as claimed 1 being disposed in a two wheeled or a three wheeled vehicle.

13. The electric motor assembly (100) as claimed in claim 10, wherein the power is transmited from the power modules (150,155,160) to the motor (105) through a separate angled phase terminal (156).

14. The electric motor assembly (100) as claimed in claim 9, wherein said anode (135) having a plate and a power terminal (135’) together forming said anode (135), said cathode (140) having a plate and a cathode power terminal (140’) together forming the cathode (140).

15. The electric motor assembly (100) as claimed in claim 14, wherein said anode power terminal (135’) connecting to a negative terminal of a batery, and said anode (135) having a plurality of electrical anode connectors (135a, 135b, 135c) projecting outwards of said anode (135), each said electrical connectors (135a, 135b, 135c) connecting to a negative terminal or bus of each power module (150, 155, 160).

16. The electric motor assembly (100) as claimed in claim 14, wherein said cathode power terminal (140’) connecting to a positive terminal of a batery, and said cathode (140) having a plurality of electrical cathode connectors (140a, 140b, 140c) projecting outwards of said cathode (140), each said electrical connectors (140a, 140b, 140c) connecting to a positive terminal or bus of each power module (150, 155, 160)