Busbar assembly for an electric drive unit

Abstract

A busbar assembly for an electric, drive unit (EDU) included on a battery electric vehicle (BEV), comprising a fluid inlet for receiving a supply of fluid: and a shaped cover, formed from an electrically insulating material, having a plurality of elongated fluid channels positioned adjacent to each other, m fluid communication with the fluid inlet, each shaped to receive and at least partially surround a busbar conductor.

Description

4.556 (8887-3392003) BUSBAR ASSEMBLY FOR AN ELECTRIC DRIVE UNIT TECHNICAL FIELD

[0001] The present application relates to electric drive units and, moreparticularly, to busbars used in the electric drive units. BACKGROUND

[0002] Modern vehicles are increasingly propelled by one or more electricmotors. The vehicles can include a vehicle battery storing electrical voltage that is electrically coupled to the electric motor(s) via an inverter and other power electronics that can invert the direct current (DC) voltage supplied by the vehicle battery into alternating current (AC) electrical current received by the electric motor. The process of supplying electrical current to the electric motor can generate significant amounts of heat that can diminish the performance of the inverter. It may be helpful to implement effective strategies for reducing the amount of heat generated by supplying electrical current to an electric motor on a vehicle. SUMMARY

[0003] In one implementation, a busbar assembly for an electric drive unit(EDU) included on a battery electric vehicle (BEV), comprises a fluid inlet for receiving a supply of fluid; and a shaped cover, formed from an electrically insulating material, having a plurality of elongated fluid channels positioned adjacent to each other, in fluid communication with the fluid inlet, each shaped to receive and at least partially surround a busbar conductor.

[0004] In another implementation, a busbar assembly for an EDU includedon a BEV, comprises a plurality of planar busbar conductors configured to electrically couple to an inverter and a rotating electrical machine; a shaped cover, formed from an electrically insulating material, having a plurality of elongated4.556 (8887-3392003) fluid channels, in fluid communication with the fluid inlet, that each receives one of the planar busbar conductors; and a fluid manifold, for receiving a supply of fluid, in fluid communication with the plurality of elongated fluid channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a block diagram depicting an implementation of anelectric drive unit that can include a busbar assembly;

[0006] Figure 2 is a perspective view depicting an implementation of abusbar assembly; and

[0007] Figure 3 is a perspective view depicting another implementation of abusbar assembly. DETAILED DESCRIPTION

[0008] An electric drive unit (EDU) includes a battery, a rotating electricalmachine or electric motor, and a busbar assembly that electrically couples a control system including an inverter to the rotating electrical machine. Modern EDUs typically have batteries that supply a relatively high level of direct current (DC) voltage through battery terminals. In one example, the battery can output 800 volts DC. The busbar assembly can electrically couple the control system / inverter that regulates the voltage supplied through the battery terminals and inverts it to alternating current (AC) before it reaches the stator wires of the rotating electrical machine. Application of voltage through the busbar assembly at the voltage levels typically output by batteries used by EDUs can generate significant amounts of heat, especially near the rotating electrical machine. It is possible to compensate for increased levels of heat by increasing the size and / or thickness of busbar conductors of the busbar assembly. However, increased size / thickness can also increase cost. It would be helpful to decrease the amount of heat emitted by the busbar assembly while also electrically isolating individual conductors of the busbar assembly.4.556 (8887-3392003)

[0009] A shaped cover can be formed from a non-electrically-conductivematerial and included with the busbar assembly. The shaped cover can include a plurality of elongated fluid channels that are shaped to receive and at least partially enclose busbar conductors and have walls that face the busbar conductors as well as electrically insulate the conductors. The elongated fluid channels can extend for an axial length that matches or is less than the length of the busbar conductors such that a portion of the busbar conductors extend beyond the elongated fluid channels. The space between the busbar conductors and the walls of the elongated fluid channels can be relatively small. For example, the busbar conductors can be relatively planar and the space between the outer surface of the busbar conductors and a wall of the elongated fluid channel may be less than the width of the conductor, and closer in size to the thickness of the conductor. The shaped cover can position a plurality of the elongated fluid channels adjacent to each other to help minimize overall size. Typically, busbar assemblies provide significant amounts of space to prevent voltage creepage between conductors or sufficient insulation having enough space and dielectric strength to isolate the conductors. The proposed busbar assembly can help minimize the amount of space consumed. A fluid inlet or fluid manifold can be formed in the shaped cover and in fluid communication with the plurality of elongated fluid channels at one end. Pressurized fluid, such as transmission fluid, can be supplied by the EDU to the fluid inlet or manifold such that the fluid flows through the elongated fluid channels over the outer surfaces of the busbar conductors and exiting the elongated fluid channels at a distal end. The fluid flow over the busbar conductors can help cool the busbar conductors and reduce the temperature of the busbar assembly.

[0010] An implementation of an electric drive unit (EDU) 10 is shown inFigure 1 having a rotating electrical machine 12 (also referred to as an electric motor) that at least partially provides propulsion to a battery electric vehicle (BEV). In addition to the electric motor 12, the EDU 10 can include a battery 14, a control system 16 including an inverter that inverts DC voltage stored in the battery 14, and a busbar assembly 18 that electrically couples the control system / inverter 16 to stator windings (not shown) of the electric motor 12. The4.556 (8887-3392003) term “battery electric vehicle” or “BEV” can refer to vehicles that are propelled, either wholly or partially, by rotating electrical machines or electric motors. BEV can refer to electric vehicles, plug-in electric vehicles, hybrid-electric vehicles, fuel cell vehicles, range-extended electric vehicles, and battery-powered vehicles. Vehicle should be broadly construed to include a variety of transportation modes, not limited to automobiles. The electric motor 12 can include a motor housing, a stator assembly, which is received in the motor housing, and a rotor assembly that is rotatable relative to the stator assembly about a motor axis. In one example, the electric motor 12 is a permanent magnet synchronous electrical machine. The control system / inverter 16 can convert the DC electrical power received from the battery 14 into AC electrical power to induce angular movement of the rotor relative to the stator. The control system / inverter 16 can include a plurality of switches, such as MOSFETs, that are arranged in electrical communication with the busbar assembly 18 and the electric motor 12 such that the arrangement of switches have gate inputs electrically connected to a microprocessor or microcontroller that selectively renders the switches conductive to induce the rotor assembly to rotate relative to the stator assembly. The battery 14 or batteries are rechargeable and can include lead-acid batteries, nickel cadmium (NiCd), nickel metal hydride, lithium-ion, and lithium polymer batteries, to name a few. A typical range of BEV battery voltages can range from 200 to 800V of DC electrical power (VDC). An example of an electric drive unit (sometimes referred to as an electric drive module) is described in U.S. Patent No. 11,303,183 the contents of which are incorporated by reference in their entirety.

[0011] Figure 2 depicts an implementation of the busbar assembly 18 thatincludes a plurality of busbar conductors 20 that electrically couples the control system / inverter 16 to the stator of the electric motor 12 and a shaped cover 22 having elongated fluid channels 24 that receive busbar conductors 20 included with the busbar assembly 18, electrically isolating the busbar conductors 20 and flowing fluid over the busbar conductors 20 thereby cooling the busbar assembly 18. The busbar assembly 18 can be used in environments where a level of battery voltage or current through the busbar assembly 18 is sufficient enough to benefit from or require supplemental cooling of busbar conductors 20 using a fluid. The4.556 (8887-3392003) busbar conductors 20 can be formed from an electrically conductive material, such as copper or aluminum, and have a relatively planar shape. The planar shape of the busbar conductors 26 can be defined by having a width (w) that is a multiple of magnitude of height (h). In this implementation, the busbar assembly 18 includes three planar busbar conductors 20—one for each phase—each having terminals 26 at each end. The terminals 26 can be substantially planar with apertures 28 for receiving a connector (not shown) that electrically and mechanically couples the busbar conductors 20 to the control system / inverter 16 or the stator windings of the electric motor 12. The busbar conductors 20 can each have a different length (l) and be arranged so that the planar outer surfaces of the busbar conductors 20 extend parallel to each other in relatively close proximity.

[0012] The shaped cover 22 can be formed from an electrically insulatingmaterial that is rigid enough to maintain the shape of the elongated fluid channels 24 in the face of fluid pressure created by a fluid source, such as a sump filled with transmission fluid or engine oil and a rotary pump. The material of the shaped cover 22 can be thermally conductive as well. In this implementation, the elongated fluid channels 24 can extend a length (l) approximately the same as the busbar conductors 20. The elongated fluid channels 24 can have a height (h) that is substantially greater than the width (w) of the elongated fluid channels 24 such that the busbar conductors 20 can be fully received within the elongated fluid channels 24 and no other portion of the busbar conductors 20 are exposed other than the terminals 26. A cross-section of the elongated fluid channels 24 would reveal a substantially U-shape, open at opposite ends. However, the elongated fluid channels 24 could have different cross-sectional shapes depending on the shape of the busbar conductors 20. The shaped cover 22 can include three elongated fluid channels 24 in this implementation, one for each busbar conductor 20. The elongated fluid channels 24 can be directly adjacent to or abutting each other to help create a compact busbar assembly 18. One elongated fluid channel 24 can be defined relative to another elongated fluid channel 24 by a separator wall 30 such that the separator wall 30 forms a portion of two adjacent elongated fluid channels 24. The elongated fluid channels 24 can be in fluid communication with a fluid inlet 32 that receives fluid from a pressurized fluid source (not shown),4.556 (8887-3392003) such as an oil pump fed by an oil sump. The fluid inlet 32 can include a flow restricting orifice that meters the flow of fluid through the elongated fluid channels 24. The width (w) and height (h) of the elongated fluid channels 24 can be selected, in coordination with the size of the busbar conductors 20, to control the rate of fluid flow through the elongated fluid channels 24. The fluid flowing through the elongated fluid channels 24 can envelop the planar outer surface of the busbar conductors 20 as the fluid flows through the fluid inlet 32 toward and opposite end of the elongated fluid channels 24. At the opposite end of the fluid channels 24, the fluid can return to a heat exchanger and / or a fluid sump (not shown).

[0013] Another implementation of a busbar assembly 18’ is shown in Figure3. The busbar assembly 18’ includes busbar conductors 20’ that electrically couple the control system / inverter 16 to the stator of the electric motor 12 and a shaped cover 22’ having elongated fluid channels 24’ that receive the busbar conductors 20’, electrically isolating the busbar conductors 20’ and flowing fluid over the busbar conductors 20’ thereby cooling the busbar assembly 18’. In this implementation, the busbar assembly 18’ includes three planar conductors 20’— one for each phase—each having a terminal 26 at each end. The terminals 26 can be substantially planar with an aperture 28 for receiving a connector that electrically and mechanically couples the busbar conductors 20’ to the control system / inverter 16 or the stator windings of the electric motor 12. The busbar conductors 20’ can each have a different length and be arranged so that the planar surfaces of the busbar conductors 20’ extend parallel to each other in relatively close proximity.

[0014] In this implementation, the elongated fluid channels 24’ can extenda length (l) that is different than the length of the busbar conductors 20’, leaving a portion of the busbar conductors 20’ other than the terminals 28 exposed. The elongated fluid channels 24’ can have a height (h) that is substantially greater than the width (w) such that the busbar conductors 20’ can be fully received within the elongated fluid channels 24’. A cross-section of the elongated fluid channels would reveal a substantially U-shaped cross section, open at opposite ends.4.556 (8887-3392003)

[0015] A fluid manifold 34 that is in fluid communication with the elongatedfluid channels 24’ can be formed in the shaped cover 22’. The fluid manifold 34 can include an open side 36 to receive fluid forcefully supplied to the fluid manifold 34 and communicated to the elongated fluid channels 24’. A pressurized fluid supply can be positioned adjacent the open side 36 to introduce fluid into the fluid manifold 34 so that the fluid travels along the elongated fluid channels 24’ toward an opposite end of the elongated fluid channels 24’. The fluid can flow through the elongated fluid channels 24’ enveloping the outer surface of the busbar conductors 20’ as the fluid flows from the fluid manifold 34 toward and opposite end of the fluid channels 24’, exiting the elongated fluid channels 24’. At the opposite end of the fluid channels 24’, the fluid can return to a heat exchanger and / or a fluid sump (not shown).

[0016] It is to be understood that the foregoing is a description of one or moreembodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0017] As used in this specification and claims, the terms "e.g.," “forexample,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open- ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

Claims

4. 556 (8887-3392003) CLAIMS 1. A busbar assembly for an electric drive unit (EDU) included on a battery electric vehicle (BEV), comprising: a fluid inlet for receiving a supply of fluid; and a shaped cover, formed from an electrically insulating material, having a plurality of elongated fluid channels positioned adjacent to each other, in fluid communication with the fluid inlet, each shaped to receive and at least partially surround a busbar conductor.

2. The busbar assembly recited in claim 1, wherein the plurality of elongated fluid channels have different lengths.

3. The busbar assembly recited in claim 1, wherein the busbar conductors have a planar shape.

4. The busbar assembly recited in claim 1, wherein a space between an outer surface of the busbar conductor and a wall of the elongated fluid channel is smaller than the width of the busbar conductor.

5. The busbar assembly recited in claim 1, wherein the busbar conductor has a width that is a multiple of magnitude of height.

6. The busbar assembly recited in claim 1, wherein the elongated fluid channels have a U-shaped cross section that are open at opposite ends.

7. The busbar assembly recited in claim 1, wherein adjacent elongated fluid channels are defined relative to each other using separator walls.

8. The busbar assembly recited in claim 1, further comprising a flow restricting orifice that meters fluid flow through the plurality of elongated fluid channels.

9. The busbar assembly recited in claim 1, further comprising a fluid manifold in fluid communication with the fluid inlet.4.556 (8887-3392003) 10. The busbar assembly recited in claim 9, wherein the fluid manifold has an open end.

11. A busbar assembly for an electric drive unit (EDU) included on a battery electric vehicle (BEV), comprising: a plurality of planar busbar conductors configured to electrically couple to an inverter and a rotating electrical machine; a shaped cover, formed from an electrically insulating material, having a plurality of elongated fluid channels, in fluid communication with the fluid inlet, that each receives one of the planar busbar conductors; and a fluid manifold, for receiving a supply of fluid, in fluid communication with the plurality of elongated fluid channels.

12. The busbar assembly recited in claim 11, wherein the fluid manifold is positioned at one end of the plurality of elongated fluid channels.

13. The busbar assembly recited in claim 11, wherein the plurality of elongated fluid channels have different lengths.

14. The busbar assembly recited in claim 11, wherein a space between an outer surface of the busbar conductor and a wall of the elongated fluid channel is smaller than the width of the busbar conductor.

15. The busbar assembly recited in claim 11, wherein the elongated fluid channels have a U-shaped cross section that are open at opposite ends.

16. The busbar assembly recited in claim 11, wherein adjacent elongated fluid channels are defined relative to each other using separator walls.

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