Busbar Assemblies

Abstract

A bus bar assembly for an electric vehicle, the bus bar assembly having a bus bar for power distribution and a connector, wherein the bus bar includes a body made of a first conductive material, the body defining a recess, a plurality of graphene layers arranged in the recess, and the graphene layers contacting the body.

Description

Technical Field

[0001] The present invention relates to a bus bar assembly for power distribution in an electric vehicle. The field of the invention is more specifically the field of hybrid or electric vehicles, in which energy is stored in batteries. Electric vehicles (EVs) employ a set of hybrid technologies in their various systems. For example, there are energy storage systems that store and distribute large amounts of electrical energy. High performance semiconductor devices are used to control the storage and distribution to achieve very fast switching to drive electric motors, among other purposes. Background Art

[0002] It is well known that busbars are commonly used for power distribution. Simply put, a busbar is a conductive metal strip or strip and is used for power distribution. Power distribution equipment, including switchboards, switchgear and motor control centers, use busbars to connect circuit breakers and other protective devices to loads.

[0003] For decades, the industry has used copper or aluminum bus bars to connect large semiconductor modules to their associated capacitors, DC buses, and output buses. However, there remains a need to improve conventional copper or aluminum bus bars.

[0004] For example, US2012305283A1 discloses a busbar comprising multiple layers. The busbar is a special formable low inductance high current capacity busbar that mixes power electronic devices, semiconductor arrays and other devices into a single hybrid structure. Each busbar layer is made of a formed busbar material (e.g., copper, aluminum, etc.). An electrically insulating dielectric (e.g., a dielectric layer) is inserted between each busbar layer. The dielectric layer includes a film of polyester, Kapton, etc., which provides an insulating laminate layer suitable for the voltage and current carried by the busbar layer.

[0005] WO2022117438 discloses a busbar made of bimetal, and the bimetal includes copper and aluminum or a copper alloy and an aluminum alloy in order to reduce costs.

[0006] Copper and aluminum are two of the most commonly used materials for bus bars. Copper is a heavy material, while aluminum does not perform as well as copper in terms of electrical properties. Aluminum has a lower electrical conductivity than copper. Therefore, combining both aluminum and copper materials may reduce the performance of the bus bar compared to a typical copper bus bar.

[0007] A lot of research work has been devoted to improving the electrical conductivity of copper. For example, from US2018102197A1 and US2020294685A1, composite structures using copper and graphene are known, which have improved electrical conductivity compared to copper alone. However, such composite structures are complex and not always suitable for any commercial application. Summary of the invention

[0008] An object of the present invention is to provide an improved busbar having reduced weight and reduced cost without degrading the performance of the busbar. Therefore, the present invention relates to a busbar assembly for an electric vehicle according to claim 1. The busbar assembly has a busbar for power distribution and a connector. The busbar assembly includes a body made of a first conductive material. The body defines a recess, a plurality of graphene layers are arranged in the recess, and the graphene layers are in contact with the body. The graphene layers may be in direct contact or indirect contact with the body.

[0009] Thus, graphene is coupled to a first conductive material. The first conductive material is a conventional busbar material, such as copper or aluminum. Graphene is an atom thick, two-dimensional carbon material currently used for electrical, thermal, and mechanical applications. The carbon atoms in graphene are covalently bonded in a honeycomb (hexagonal) lattice. Graphene is very thin, flexible, and conductive. Any graphene coverage or graphene structure that can enhance the conductivity of the busbar can be used.

[0010] By combining several layers of parallel graphene (such as in battery cell production technology), the same electrical properties as copper can be achieved. Therefore, the busbar assembly can have a reduced amount of copper or aluminum compared to conventional aluminum or copper busbars without reducing electrical performance. The main body is an external body and is made of a conventional conductive material, making the integration of such a busbar easy to carry out. In addition, the resistivity of graphene is 1 / 5 of that of copper, and the resistance of copper depends on the cross-section, which is not the case with graphene. Finally, graphene is lighter and cheaper than copper, for example, the busbar assembly can have a reduced weight without increasing the size or price of the busbar. Relatively speaking, the final product using graphene can be several times smaller than a copper busbar. Therefore, the busbar provides a multilayer conductive structure with high current capacity and low inductance.

[0011] In an embodiment, a spacer is provided between each graphene layer, and wherein the spacer is made of an electrically insulating material. The spacer provides an insulating layer suitable for the voltage and current carried by the busbar (more specifically, by the graphene layer). The spacer is as thin as possible while providing an insulating function to reduce the inductance caused by the current in the graphene layer.

[0012] In an embodiment, the spacer is made of paper. Therefore, the weight and size are limited. The spacer can also be a glue or coating / paint material.

[0013] In an embodiment, the body comprises at least one wall and a strip, the at least one wall defining the recess, the strip protruding from the wall within the recess, and wherein the graphene layer is in contact with the strip. Thus, the graphene layer is in contact with the strip made of conventional busbar material. The graphene layer is physically mounted to the body acting as a base structure and is electrically connected through the body.

[0014] In an embodiment, at least one graphene layer comprises a first longitudinal portion in contact with at least one strip and a second longitudinal portion not in contact with the strip. Thus, the graphene layer is supported by the strip. The strip can provide some robustness. However, such a strip does not support the entire length of all graphene layers. Thus, the amount of the first conductive material is reduced.

[0015] In an embodiment, the graphene layer extends a non-zero distance from the at least one wall. This allows a compact structure.

[0016] In an embodiment, the body is a parallelepiped and comprises a bottom wall, a top wall, and a first side wall and a second side wall extending between the bottom wall and the top wall, wherein the bottom wall, the top wall and the two side walls define the recess, and wherein the strip protrudes from the first side wall and / or the second side wall. In an embodiment, each graphene layer is in contact with a first strip protruding from the first side wall and a second strip protruding from the second side wall. These strips provide support for the free ends of the graphene layers.

[0017] In another embodiment, the body has a thickness of less than 5 mm. Thus, a compact structure is achieved.

[0018] In another embodiment, from the cross section, the recess has a recess length Lr, the spacer has a spacer length Ls, and the graphene layer has a graphene length Lg. The graphene length is less than the spacer length, and wherein the spacer length is less than the recess length.

[0019] In an alternative embodiment, the body is cylindrical and the graphene layers are arranged concentrically with each other.

[0020] In an embodiment, an electrically insulating spacer is arranged at a middle position of the cylinder, and the core of the cylinder is formed by the spacer.

[0021] In an embodiment, the spacers between each graphene layer are arranged concentrically with each other.

[0022] In an embodiment, the first conductive material is copper. The combination of copper and graphene allows for good electrical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention and its advantages will be better understood by reading the following description, which is given by way of example only and with reference to the accompanying drawings, in which:

[0024] Figure 1 shows a perspective view of a bus bar assembly according to a first embodiment, wherein the bus bar has a parallelepiped body and a connector;

[0025] Figure 2A shows a schematic perspective view of a busbar assembly according to a second embodiment, wherein the busbar has a cylindrical body and a connector, and for better understanding, the different layers of the busbar are schematically uncovered;

[0026] Figure 2B Shows Figure 2A Cross section of a busbar assembly. DETAILED DESCRIPTION

[0027] The embodiments disclosed herein will be best understood by reference to the accompanying drawings, in which like reference numerals represent like or similar elements. It will be readily appreciated that the components of the disclosed embodiments may be arranged and designed in a variety of different configurations, as shown in the general description herein and in the accompanying drawings. Therefore, the following detailed description of embodiments of the systems and methods disclosed herein is not intended to limit the scope of the disclosure as claimed, but is merely representative of possible embodiments of the disclosure.

[0028] Figure 1 , Figure 2A and Figure 2B A bus bar assembly 10 is shown. The bus bar assembly 10 includes a connector 12 and a bus bar 14 for power distribution. The connector 12 is adapted to electrically connect the bus bar 14 to a battery component or any other component.

[0029] The busbar 14 includes a body 16 made of a first conductive material. The first conductive material may be, for example, copper, aluminum, etc. In a preferred embodiment, the first conductive material is copper. The body 16 defines a recess 18, and a plurality of graphene layers 201, 202, ... 20n extend in the recess. The graphene layers 201, 202, ... 20n are in direct or indirect contact with the body 16.

[0030] exist Figure 1 In the embodiment, according to the first embodiment, the body 16 has a parallelepiped shape and has a top wall 22, a bottom wall 24, and a first side wall 26 and a second side wall 28 extending between the top wall and the bottom wall. The top wall 22, the bottom wall 24, and the first side wall 26 and the second side wall 28 define the recess 18. For example, Figure 1As shown, the recess 18 has a rectangular cross-section. However, in other embodiments, the recess 18 can have other shapes. The body 16 includes a plurality of strips 30. These strips 30 can be integral with the walls 22, 24, 26, 28. In another embodiment, these strips are not integral with the walls, but are fixed to the walls. These strips 30 can extend from the first side wall 26 and / or the second side wall 28 into the recess 18. For example, a plurality of first strips 30 are arranged on the first side wall. A plurality of second strips 30 are also arranged on the second side wall. These strips 30 protrude within the recess 18, but the length Lst of these strips is less than the length Lr of the recess. More specifically, the first strips and the second strips 30 do not contact each other, and there is a gap between the strips extending from the first side wall 26 and the strips extending from the second side wall 28.

[0031] The first and second strips 30 may support graphene layers 201, 202, ... 20n. More specifically, a plurality of graphene layers 201, 202, ... 20n are arranged in the recess 18. The graphene layers 201, 202, ... 20n extend parallel to each other. The graphene layers 201, 202, ... 20n are supported on one side by the first strip and / or on the other side by the second strip. Between each graphene layer 201, 202, ... 20n, a spacer 32 is arranged. The spacer 32 is made of an insulating material. The spacer 32 is, for example, a paper layer. Figure 1 A few graphene layers are schematically shown. However, the number of graphene layers can be up to several thousand layers.

[0032] like Figure 1 As schematically depicted in , the first graphene layer 201 can be placed on the bottom wall 24. The spacer 32 is arranged above the first graphene layer 201. The second graphene layer 202 is arranged above the spacer 32. The second graphene layer 202 can be in contact with the first strip at the first end and in contact with the second strip at the second end. Therefore, the second graphene layer 202 includes a first longitudinal portion in contact with the first strip, a second longitudinal portion not in contact with the strip, and a third longitudinal portion in contact with the second strip. Above the second graphene layer 202 and the strip, another spacer 32 is arranged. Then, the third graphene layer 203 is stacked (or piled) on the other spacer. Similar to the second graphene layer, the third graphene layer 203 is in contact with the second first strip at the first end and in contact with the second second strip at the second end. The stacking of graphene layers 201, 202, ... 20n and spacers 32 and strips 30 continues in the same manner until the top wall 22, with the last graphene layer 20n in contact with the top wall 22. Thus, all graphene layers 201, 202, ... 20n are in contact with the first conductive material and are separated by spacers.

[0033] The body may, for example, have a thickness th of less than 5 mm, for example, a thickness of about 3 mm. From the cross section, it can be seen that the recess has a recess length Lr, the spacer has a spacer length Ls, and the graphene layer has a graphene length Lg. The graphene length Lg is less than the spacer length Ls. The spacer length Ls is less than the recess length Lr.

[0034] Figure 2A and Figure 2B A busbar assembly according to a second embodiment is shown. The body 16 is cylindrical and has a circular cross-section. The body 16 defines a cylindrical recess 18. The graphene layers 201, 202, ... 20n are parallel and arranged concentrically with each other in the recess. An electrically insulating spacer is provided at a middle position of the cylindrical body. Between each graphene layer 201, 202, ... 20n, a spacer 32 is arranged. The spacer 32 is also arranged concentrically with each other and with the graphene layer. The body can be in direct contact with the first graphene layer, or as shown, the body can be in surface contact with the spacer. The strip 30 is arranged to connect each graphene layer to the body. The spacer 32 is made of an insulating material. The spacer is, for example, a paper layer.

[0035] exist Figure 1 and Figure 2A In an embodiment of the present invention, the spacer 32 may have a thickness of about 5 to 30 microns. The graphene layer may have a thickness of 100 nanometers to 10 microns. The strip may have a thickness of about 10 to 100 microns.

[0036] The bus bar assembly 10 described above can be used, for example, in a battery system. The bus bar is connected to at least one battery component via a connector 12 .

[0037] Bus bar assembly 10

[0038] Connector 12

[0039] Busbar 14

[0040] Body 16

[0041] Recess 18

[0042] Graphene layers 201, 202, ... 20n

[0043] Top wall 22

[0044] Bottom wall 24

[0045] The first side wall 26 and the second side wall 28

[0046] Strip 30

[0047] Strip length Lst

[0048] Recess length Lr

[0049] Spacer length Ls

[0050] Graphene length Lg

[0051] Main body thickness th

[0052] Isolation 32

Claims

1. A bus bar assembly (10) for an electric vehicle, the bus bar assembly (10) having a bus bar (14) for power distribution and a connector (12), wherein the bus bar comprises: A body (16) is made of a first conductive material, the body defining a recess (18), a plurality of graphene layers (201, 202, ... 20n) being arranged in the recess (18), and wherein the graphene layers (201, 202, ... 20n) are in contact with the body (16).

2. The busbar assembly (10) according to claim 1, wherein: A spacer (32) is arranged between each graphene layer (201, 202, ... 20n), and wherein the spacer is made of an electrically insulating material.

3. The busbar assembly (10) according to claim 2, wherein: The separator (32) is made of paper.

4. The busbar assembly (10) according to any one of claims 1 to 3, wherein: The body (16) comprises at least one wall (22, 24, 26, 28) and a strip (30), the at least one wall delimiting the recess (18), the strip (30) protruding within the recess, and the graphene layer (201, 202, ... 20n) being in contact with the strip.

5. The busbar assembly (10) according to claim 4, wherein: Each graphene layer (201, 202, ... 20n) comprises a first longitudinal portion in contact with at least one stripe and a second longitudinal portion not in contact with the stripe.

6. The busbar assembly (10) according to claim 4 or 5, wherein: The graphene layer (201, 202, ... 20n) extends a non-zero distance from the at least one wall (22, 24, 26, 28).

7. The busbar assembly (10) according to any one of claims 4 to 6, wherein: The body (16) is a parallelepiped and comprises a bottom wall (24), a top wall (22) and a first side wall (26) and a second side wall (28) extending between the bottom wall and the top wall, wherein the bottom wall, the top wall and the two side walls define the recess, and wherein the strip protrudes from the first side wall and / or the second side wall.

8. The bus bar assembly (10) according to claim 7, wherein: Each graphene layer (201, 202, ... 20n) is in contact with a first strip protruding from the first side wall (26) and a second strip protruding from the second side wall (28).

9. The busbar assembly (10) according to claim 6 or 7, wherein: The body (16) has a thickness of less than 5 mm.

10. The busbar assembly (10) according to claim 2 and any one of claims 1 to 9, wherein: From the cross section, it can be seen that the recess (18) has a recess length Lr, the spacer has a spacer length Ls, and the graphene layer has a graphene length Lg, and wherein the graphene length is smaller than the spacer length, and wherein the spacer length is smaller than the recess length.

11. The busbar assembly (10) according to any one of claims 1 to 7, wherein: The body is cylindrical, and the graphene layers (201, 202, ... 20n) are arranged concentrically with each other.

12. The bus bar assembly (10) according to claim 10, wherein: An electrical insulating spacer (32) is arranged at the middle position of the cylinder.

13. The busbar assembly (10) according to any one of claims 1 to 12, wherein: The first conductive material is copper.

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