Low inductance busbar assembly for electric drive units

Abstract

A busbar assembly for use in a vehicle, comprising: a direct current (DC) link busbar configured to be electrically coupled to a vehicle battery and a plurality of switches implementing an inverter, conducting current to an electric motor of the vehicle, the DC link busbar comprising a plurality of DC electrical conductors having a substantially symmetrical shape, wherein the electrical conductors are stacked such that adjacent DC electrical conductors have opposite polarity; a phase busbar adjacent to the DC link busbar, the phase busbar configured to electrically couple the plurality of switches to a stator of the electric motor; and a DC link connector extending radially outwardly from the DC link busbar, the DC link connector configured to electrically couple the DC link busbar with a bulk capacitor.

Description

[0001] Priority Statement This application claims priority to U.S. Provisional Application No. 63 / 564,625, filed March 13, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to an electric drive unit for use in a battery electric vehicle (BEV), and more specifically, to a busbar assembly for use in the electric drive unit. Background Technology

[0003] Modern battery electric vehicles (BEVs) include a series of electrical components that convert stored electrical energy into electricity selectively powering the vehicle. The BEV may include a vehicle battery that stores electrical energy, as well as power electronics that convert the stored energy into current to propel a rotating motor that drives the BEV. The efficiency with which the electrical components perform this conversion significantly impacts the BEV's range and performance. Improving the design of these electrical components to enhance BEV performance and / or more effectively utilize the electrical energy stored in the vehicle battery would be beneficial. Summary of the Invention

[0004] In one implementation, a busbar assembly for use in a vehicle includes: a DC link busbar configured to be electrically coupled to a vehicle battery and to implement multiple switches of an inverter to conduct current to an electric motor of the vehicle, the DC link busbar including multiple DC conductors having a substantially symmetrical shape, wherein the conductors are stacked such that adjacent DC conductors have opposite polarities; a phase busbar adjacent to the DC link busbar, the phase busbar being configured to electrically couple the multiple switches to the stator of the electric motor; and a DC link connector extending radially outward from the DC link busbar, the DC link connector being configured to electrically couple the DC link busbar to a bulk capacitance (energy storage capacitor).

[0005] In another implementation, a busbar assembly for use in a vehicle includes: a substrate having holes positioned around its periphery; a plurality of switches carried by the substrate having pins extending through the holes to implement an inverter; a DC link busbar configured to electrically couple to a vehicle battery and the plurality of switches to conduct current to a motor of the vehicle, the DC link busbar including a plurality of DC conductors having a substantially symmetrical shape, wherein the conductors are stacked such that adjacent DC conductors have opposite polarities; a phase busbar adjacent to the DC link busbar, the phase busbar configured to electrically couple the plurality of switches to the stator of the motor; and a DC link connector extending radially outward from the DC link busbar, the DC link connector being configured to electrically couple the DC link busbar to a large-capacity capacitor. Attached Figure Description

[0006] Figure 1 It is an exploded view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 2 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 3 It is an exploded view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 4 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 5 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 6 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 7 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 8 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 9 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 10 It is a plan view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 11It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 12 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 13 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 14 It is a cross-sectional view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 15 It is a perspective and partial sectional view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 16 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 17 It is a cross-sectional view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 18 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 19 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 20 It is a cross-sectional view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 21 It is a perspective view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 22 It is a cross-sectional view depicting one implementation of a busbar assembly used with an electric drive unit; Figure 23 It is a cross-sectional view depicting one implementation of a busbar assembly used with an electric drive unit. Detailed Implementation

[0007] An electric drive unit typically includes a battery and power electronics. The battery supplies direct current (DC) power to a rotating or electric motor via a busbar assembly, and the power electronics include an inverter. An example of such an electric drive unit is described in U.S. Patent No. 11,863,046, the entire contents of which are incorporated herein by reference. The busbar assembly described herein can be used with an electric drive unit. The busbar assembly may include electrical conductors electrically coupled between the battery and the inverter via a DC link busbar, electrically coupled to the stator lines of the motor via a phase busbar, and electrically coupled in parallel to a large-capacity capacitor via a DC link connector. When the inverter draws current from the battery, an electromagnetic field (EMF) can be generated by the current flowing through the busbar assembly. The inductance of the busbar assembly can be expressed as the ratio of the magnetic flux to the amount of current carried through the busbar assembly. The presence of an EMF generated by the current flow may be undesirable because an increased EMF increases the inductance of the busbar assembly.

[0008] Busbar assemblies can minimize inductance using selected construction and arrangement of electrical conductors. For example, a busbar assembly may include a substrate that hosts a stack of electrical conductors with alternating polarities and substantially symmetrical shapes. This stack may include DC conductors electrically coupling a battery to an inverter, and AC busbars or phase busbars electrically coupling the inverter to the stator windings of a motor. The size and shape of electrical connectors of the DC conductors or phase busbars, capable of electrically coupling to the switching or stator windings of the inverter, can also be designed to minimize or reduce the total inductance of the busbar assembly. In some implementations, the electrical connectors may have increased width, thickness, and / or contoured (contoured) terminal shapes to reduce inductance. The busbar assembly may employ a layered and laminated construction having a portion comprising annular electrical conductors with alternating polarities and a relatively thin insulating layer separating the conductors. Electrical conductors with alternating positive and negative polarities may be formed to use the same shape and contour over the entire area of ​​the conductors, thereby further reducing the inductance of the busbar assembly. The ring-shaped portion of the conductor allows multiple MOSFET switches included in the inverter to be positioned back-to-back, with the switch bodies abutting each other. Furthermore, the busbar assembly can be electrically coupled to symmetrically arranged large-capacity capacitors using DC conductors and DC link connectors. This combination of features can significantly reduce the total inductance of the busbar assembly.

[0009] about Figures 1 to 12These illustrate an implementation of the busbar assembly 10. The busbar assembly 10 may include a substrate 12 carrying a DC link busbar 14, a phase busbar 16, and a plurality of electrical switches 18 used at least partially to implement an inverter. The substrate 12 may have a substantially circular shape and be formed of an electrically insulating material. A plurality of holes 20 may be formed around the periphery of the substrate 12. The holes 20 may be shaped to receive terminals of the switches 18 used to implement the inverter. In one implementation, the switches 18 are implemented using SiC MOSFET switches. For example, the switches 18 may be implemented using TO-247 type MOSFETs, each having four pins 22, such that the substrate 12 may have radially outwardly extending line-positioned holes 20 to receive the pins 22 of the MOSFETs. The holes 20 may be shaped and positioned in the substrate 12 such that the MOSFETs are positioned adjacent to each other on one side of the substrate 12, around the outer diameter 24 of the substrate 12, such that the bodies of adjacent MOSFETs abut against each other in such a way that the portions of the MOSFETs having the largest surface area are in contact with each other. The pin 22 of the MOSFET can pass through the hole 20, so that the pin 22 is exposed on the opposite side of the substrate 12.

[0010] DC link bus 14 can electrically couple the battery to the inverter. DC link bus 14 can be positioned on opposite sides of substrate 12 such that MOSFET pins 22 can be electrically coupled to DC conductors 26. DC link bus 14 may include a plurality of DC conductors 26, portions of which each have a substantially similar circular or annular structure. The outer diameter 28 of the DC conductors 26 can each be consistent, such that one DC conductor 26 has the same outer diameter 28 and profile as another DC conductor 26. The inner diameter 30 and profile can also be matched for DC conductors 26 having an inner diameter 30. At a point along the outer diameter 28 of the DC conductor 26, a substantially planar DC link connector 32 can extend radially outward from the DC conductor 26. This planar DC link connector 32 can be electrically coupled in parallel to a large-capacity capacitor 44. The DC link connector 32 will be discussed in more detail below. The plurality of DC conductors 26 can be separated by a relatively thin electrical insulating layer 34. For example, the electrical insulating layer 34 may comprise a flexible, electrically insulating, and temperature-resistant polyimide film. One implementation of the electrical insulating layer may be Kapton™, sold by DuPont. In one implementation, the thickness of the electrical insulating layer may be 0.25 mm.

[0011] Multiple electrical connectors 36 may be positioned around the outer diameter 28 of the DC conductor 26. The electrical connectors 36 may be integrally formed as part of the DC conductor 26. In one implementation, the electrical connectors 36 may include radially outwardly extending portions 38 attached to respective contacts 40, the contacts 40 being oriented substantially orthogonal to the radially outwardly extending portions 38. The contacts 40 may be positioned substantially parallel to the pins 22 of the switch 18 implemented as a MOSFET, such that the contacts 40 can be electrically connected to the pins 22 via soldering, welding, or other types of conductive connections. The shape of the electrical connectors 36 may be selected to help minimize the inductance of the busbar assembly 10. For example, the width (W) of the contacts 40 may be greater than the width (w) of the pins 22, thereby helping to minimize the inductance of the busbar assembly 10 by reducing the gap or space between adjacent contacts 40. Furthermore, the radially outward extension 38 may have an offset section 42 that places a portion of the radially outward extension 38 in a non-coaxial relationship with the remainder of the radially outward extension 38. The offset section 42 can bring adjacent contacts 40 closer together, thereby reducing the gap or space between adjacent contacts 40 and helping to reduce the total inductance of the busbar assembly 10.

[0012] One implementation of DC link bus 14 includes a stack of items extending from top to bottom, such as the following ( Figure 10 As shown): substrate 12, first negative DC conductor 26a, electrical insulating layer 34, second negative DC conductor 26a, electrical insulating layer 34, first positive DC conductor 26b, electrical insulating layer 34, second positive DC conductor 26b, electrical insulating layer 34, followed by phase bus 16. Phase bus 16 can be positioned such that it abuts against electrical insulating layer 34 and is separated from the second positive DC conductor 26b by electrical insulating layer 34. Positioning the negative DC conductor 26a directly above the positive conductor 26b can reduce the inductance of the bus assembly 10 by canceling out the magnetic field generated by the negative DC conductor 26a with the magnetic field generated by the positive DC conductor 26b. In other words, the magnetic field generated by the flow (or change in flow) of the current flowing through the negative polarity DC link conductor 26a can be positioned at 180 degrees relative to the magnetic field generated by the flow (or change in flow) of the current flowing through the positive polarity DC link conductor 26b, thus canceling each other out.

[0013] exist Figures 13 to 19The diagram illustrates one implementation of a portion 48 of a DC conductor 26 electrically coupled to a large-capacity capacitor 44. The portion 48 of the DC conductor 26 can be coupled to a ring-shaped portion of the DC conductor 26 via a DC link connector 32. The DC link connector 32 may include planar regions of the DC conductor 26, which exist in the amount and order of stacking as described above. In this implementation, the DC link connector 32 may include a conductive connector 50 that releasably connects discrete portions of the DC conductor 26. However, as will be discussed below, the DC conductor 26 may be formed as a single integral structure, such that the DC conductor 26 and the portion 48 coupled to the large-capacity capacitor 44 can each be formed from a single piece of material, thus eliminating the need for conductive connectors. The DC conductor 26, together with the electrically insulating layer 34, may include a portion 48 extending into a housing 46 that surrounds the large-capacity capacitor 44. In this implementation, the DC link connector 32 and the portion 48 of the DC conductor 26 extending into the housing 46 are electrically coupled to the DC conductor 26 via the conductive connector 50. The portion 48 includes a first negative DC conductor 26a, an electrical insulating layer 34, a second negative DC conductor 26a, an electrical insulating layer 34, a first positive DC conductor 26b, an electrical insulating layer 34, and a second positive DC conductor 26b. The portions of the DC conductors 26 and 34 extending within the housing 46 may be substantially symmetrical and have the same external profile, allowing them to fit within the housing 46. As described above, positioning the negative DC conductor 26a directly above the positive conductor 26b can reduce the inductance of the busbar assembly 10 by canceling out the magnetic field generated by the negative DC conductor 26a with that generated by the positive DC conductor 26b. Reducing the inductance of the busbar assembly 10 by 33% or more is possible.

[0014] A portion 48 of the DC conductor 26 extends into the housing 46 to be electrically coupled to a large-capacity capacitor 44, which includes multiple individual capacitors 54. The DC link 32 may extend a certain length along the outer surface of the housing 46 before extending into the housing 46 and being electrically connected to the large-capacity capacitor 44. The DC link 32 may include an angled bend, which may be less than ninety degrees, to facilitate electrical connection between the portion 48 of the DC conductor 26 extending into the housing 46 and the annular or circular portion of the DC conductor 26. An angled bend of less than ninety degrees minimizes the degradation of the electrical insulation layer 34.

[0015] The conductive connector 50 can be implemented in a variety of different ways. For example, the end terminals 56 of the discrete portion of the DC conductor 26 can be deflected or bent to offset relative to the corresponding end terminals 58 of other discrete portions of the DC conductor 26, such that the end terminals 56, 58 abut against each other and form a conductive connection. In this implementation, the end terminals 56 of the portion 48 of the DC conductor 26 extending into the housing 46 can have end terminals 56 of first and second negative polarity DC conductors 26a, and end terminals 56 of first and second positive polarity DC conductors 26b. The end terminals 56 of the negative polarity DC conductor 26 can be offset to be positioned between the end terminals 58 of the corresponding negative polarity DC conductor 26a. The end terminals 56 of the portion 48 of the DC conductor 26 extending into the housing 46 may have end terminals 56 of a first positive DC conductor 26b and a second positive DC conductor 26b, the end terminals 56 being positioned between corresponding end terminals 58 of the positive DC conductor 26b; one end terminal 58 may be offset to abut against the second positive DC conductor 26b. The electrical insulating layer 34 may be bonded to the DC conductor 26 using an adhesive to facilitate the conductive connector 50 and to maintain the electrical insulating layer 34 in the correct orientation relative to the DC conductor 26.

[0016] The conductive connector 50 can be secured to the housing 46, and a clamping rod assembly 60 can be used to facilitate the continuity of the electrical connection within the conductive connector 50. The clamping rod assembly 60 includes a mounting portion 62 located on the outer surface of the housing 46 and an elongated clamping rod 64 that compresses the end terminals 56, 58 at the DC link connector 32 and pulls the DC link connector 32 toward the outer surface of the housing 46, thereby securing the DC link connector 32 against the housing 46. In one implementation, the mounting portion 62 may include a plurality of ribs 66 formed on the outer surface of the housing 46 and extending linearly perpendicular to the orientation of the elongated clamping rod 64. The ribs 66 may protrude above the outer surface of the housing 46, such that the DC link connector 32 can be pressed into the ribs 66 rather than into the outer surface of the housing 46. In this implementation, the housing 46, including the ribs 66, may be formed of plastic, while the elongated clamping rod 64 may be formed of steel. However, it should be understood that other materials can be chosen for these components. Mounting portion 62 may include a threaded receptacle 68 that can releasably accommodate a threaded fastener 70 such as a stud or bolt. DC link connector 32 may be positioned over rib 66 such that conductive connector 50 and end terminals 56, 58 engage with rib 66. An elongated clamp 64 may be positioned on the surface of end terminals 56, 58 opposite to the surface of the engaging ribs of end terminals 56, 58.

[0017] The elongated clamp 64 may include a hole 72 for receiving a threaded connector 70, and one or more biasing features 74 that contact the end terminals 56, 58. The elongated clamp 64 may be stamped from conductive metal, and the biasing features 74 may be integrally formed from stamped metal in the form of contacts 78 extending away from the elongated clamp 64 and toward the end terminals 56, 58. The thickness, shape, and deflection angle of the contacts 78 may each be selected or fine-tuned to produce a desired spring force. However, it should be understood that other implementations are possible, in which the biasing features are formed independently of the elongated clamp. The threaded connector 70 (in this implementation, a threaded stud) may pass through the hole 72 to engage with the threaded receiving portion 68. A threaded nut 76 may engage with the threaded connector 70 to secure the elongated clamp 64 to the DC link connector 32 and the housing 46. When the threaded connector 70 is tightened and the elongated clamp 62 is pulled closer to the rib 66, the DC link connector 32 is secured to the housing 46, and the electrical connection between the end terminals 56 and 58 can be maintained, thereby helping to maintain electrical continuity between the discrete portions of the DC conductor 26. In this implementation, the discrete portions of the DC conductor 26 can then be separated by loosening the threaded nut and separating the discrete portions of the DC conductor at the conductive joint. However, other implementations are possible, in which the end terminals 56 and 58 can be brazed or mechanically welded together.

[0018] Go to Figures 20 to 22 This illustrates another implementation of the housing 46' for a large-capacity capacitor 44. The housing 46' includes a positioning feature 80 that positions the end terminals 56, 58 relative to each other and relative to the housing 46'. In this implementation, the positioning feature 80 is positioned at the mounting portion 62, and as shown... Figure 21As shown, the threaded connectors 70 extend as shown. A first positioning feature 80a may be an elongated rod abutting the outer surface of the housing 46' and having an outer surface configured to abut the end terminal 56. A second positioning feature 80b may be an elongated rod similar in shape to the first positioning feature 80a but spaced apart from it, extending between the threaded connectors 70, and also configured to abut the end terminal 56. A third positioning feature 80c may be an elongated rod spaced apart from and offset from the first and second positioning features 80a and 80b, configured to be positioned between the end terminals 56. The end terminals 56 may be positioned adjacent to the outer surface of the housing 46' such that they are engaged by the positioning features 80 and held fixed relative to the housing 46'. The end terminals 58 may be moved to engage with the end terminals 56 and with the positioning features 80. When the elongated clamp 64 is fixed, the positioning feature 80 can position the end terminal 56 in the optimal position relative to the elongated clamp 64 and the corresponding end terminal 58 to promote consistent and reliable electrical continuity between the end terminals 56 and 58.

[0019] Figure 23 Another implementation of the DC link bus 14' is described. The DC link bus 14' includes a plurality of DC conductors 26' stacked with phase-shifted polarities as discussed above, and also has a monolithic and continuous structure. The DC conductors 26' are made of a monolithic and uninterrupted sheet of material, allowing the portion 48 of the DC conductor 14' coupled to the large-capacity capacitor 44 to be implemented without the use of conductive connectors.

[0020] It should be understood that the foregoing description describes one or more embodiments of the invention. The invention is not limited to the specific embodiments disclosed herein, but is defined only by the appended claims. Furthermore, the statements contained in the foregoing description relate to specific embodiments and should not be construed as limiting the scope of the invention or the definition of terms used in the claims, unless a term or phrase is explicitly defined above. Various other embodiments, as well as various changes and modifications to the disclosed embodiments, will be apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to fall within the scope of the appended claims.

[0021] As used in this specification and claims, the terms “for example,” “e.g.,” “in other words,” “such as,” and “etc.”, as well as the verbs “comprising,” “having,” “including,” and other verb forms thereof, when used in conjunction with an enumeration of one or more parts or other items, shall be interpreted as open-ended, meaning that the enumeration shall not be construed as excluding other additional parts or items. Other terms shall be interpreted in their broadest reasonable sense unless they are used in a context that requires a different interpretation.

Claims

1. A busbar assembly for use in a vehicle, comprising: A DC link bus, configured to be electrically coupled to a vehicle battery and to enable multiple switches of an inverter to conduct current to the vehicle's electric motor, the DC link bus including multiple DC conductors having a substantially symmetrical shape, wherein the conductors are stacked such that adjacent DC conductors have opposite polarities; A phase busbar, adjacent to the DC link busbar, is configured to electrically couple the plurality of switches to the stator of the motor; as well as A DC link connector extends radially outward from the DC link busbar and is configured to electrically couple the DC link busbar to a large-capacity capacitor.

2. The busbar assembly according to claim 1, wherein each of the DC conductors has the same inner and outer diameters.

3. The busbar assembly of claim 1, wherein the DC conductor includes a plurality of electrical connectors positioned around an outer diameter and including contacts oriented orthogonal to the DC conductor and configured to abut pins of the plurality of switches.

4. The busbar assembly according to claim 3, wherein the width of the contact piece is greater than the width of the pin.

5. The busbar assembly of claim 1 further includes a substrate having a substantially circular shape and being formed of an electrically insulating material, the substrate having a plurality of holes around the periphery of the substrate, the plurality of holes being sized to receive pins of the plurality of switches and to position the plurality of switches adjacent to each other along the periphery of the substrate.

6. The busbar assembly of claim 1, wherein the DC conductor is coupled to the contact via an offset section.

7. The busbar assembly of claim 1, wherein the plurality of DC conductors comprises an ordered stack of a first negative conductor, a second negative conductor, a first positive conductor, and a second positive conductor.

8. The busbar assembly of claim 1, wherein the DC link connector further comprises a conductive connector located between the DC conductor and the portion of the DC link busbar electrically connected to the large-capacity capacitor.

9. The busbar assembly of claim 8, wherein the conductive connector further comprises a following end terminal of a discrete portion of the DC connector, the end terminal being offset relative to corresponding end terminals of other portions of the DC connector.

10. The busbar assembly of claim 8, wherein the conductive connector is secured to the housing by a clamping rod assembly.

11. The busbar assembly of claim 1, wherein the DC link connector includes an angled bend.

12. The busbar assembly according to claim 1, further comprising a housing having at least one positioning feature positioned at a mounting location for a conductive connector.

13. A busbar assembly for use in a vehicle, comprising: A substrate having holes positioned around the periphery of the substrate; Multiple switches, carried by the substrate, having pins extending through the holes, realize an inverter; A DC link bus is configured to be electrically coupled to a vehicle battery and the plurality of switches to conduct current to the vehicle's electric motor. The DC link bus includes a plurality of DC conductors having a substantially symmetrical shape, wherein the conductors are stacked such that adjacent DC conductors have opposite polarities. A phase busbar, adjacent to the DC link busbar, is configured to electrically couple the plurality of switches to the stator of the motor; as well as A DC link connector extends radially outward from the DC link busbar and is configured to electrically couple the DC link busbar to a large-capacity capacitor.

14. The busbar assembly of claim 13, wherein the substrate is substantially circular.

15. The busbar assembly of claim 13, wherein the DC conductor includes a conductive connector.

Images