Conductive composite stator unit for a vehicle motor

Abstract

A conductive composite stator unit for a vehicle electric motor is provided. The stator unit includes a stator core including a body having a first core end and an opposing second core end. The stator unit also includes a plurality of conductive rods extending from the first core end to the second core end. Each conductive rod includes a straight portion disposed within one of the slots such that the respective conductive rod is in contact with the stator core. Each conductive rod includes a central portion and an outer layer disposed around the central portion for a current to flow through with respect to the longitudinal axis, the outer layer including at least two copper-graphene (Cu-Gr) layers. Each Cu-Gr layer includes a copper layer and a graphene layer. The stator unit also includes an insulator layer disposed around each of the plurality of conductive rods.

Description

Technical Field

[0001] The present disclosure relates to a stator unit for a vehicle, and more particularly, to a conductive composite stator unit for a vehicle electric motor, wherein the stator unit has conductive bars / wires coated with a copper-graphene multilayer composite material. Background Art

[0002] With the increasing requirements for fuel efficiency and especially the reduction of greenhouse gas emissions, today's automotive industry has entered a new era of manufacturing environmentally friendly zero-emission vehicles such as battery electric vehicles. Improving electric power density and reducing energy consumption are the current challenges. Summary of the invention

[0003] Therefore, while current stator units for electric motors achieve their intended purpose, a new and improved electrically conductive composite stator unit is needed for vehicle electric motors to increase electrical power density and reduce energy consumption.

[0004] According to one aspect of the present disclosure, a conductive composite material stator unit for a vehicle electric motor is provided. The stator unit includes a stator core. The stator core includes a body having a first core end and an opposite second core end, defining a longitudinal axis. The body also has an inner radial surface extending from the first core end to the second core end relative to the longitudinal axis. The inner radial surface has a plurality of inner walls extending inwardly from the first core end to the second core end, defining an open slot formed between the respective inner walls from the first core end through the second core end.

[0005] In this regard, the stator unit also includes a plurality of conductive rods extending from the first core end to the second core end. Each conductive rod includes a central portion and an outer layer arranged around the central portion for current to flow relative to the longitudinal axis. Each conductive rod includes a straight portion arranged in one of the slots so that the corresponding conductive rod is in contact with the stator core. Each straight portion has a first radial end located at the first core end and a second radial end located at the second core end. The first radial end extends from the stator core to the first turn portion, and the second radial end extends from the stator core to the second turn portion. The outer layer includes at least two copper-graphene (Cu-Gr) layers. Each Cu-Gr layer includes a copper layer and a graphene layer. In addition, the stator unit also includes an insulator layer arranged around each of the plurality of conductive rods.

[0006] In one embodiment, the outer layer also includes a metal substrate having a first side and an opposite second side. The at least two Cu-Gr layers are a first Cu-Gr multilayer composite material disposed on the first side of the metal substrate. The outer layer also includes a second Cu-Gr multilayer composite material disposed on the second side of the metal substrate.

[0007] In one embodiment, the metal substrate has a thickness of 5 microns to 25 microns. In another embodiment, the metal substrate includes one of copper, aluminum, carbon steel and stainless steel. In yet another embodiment, the second Cu-Gr multilayer composite material includes at least two layers of Cu-Gr layers and includes copper and graphene. In addition, each layer of Cu-Gr layer in the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a thickness of 0.1 micron to 0.5 micron.

[0008] In one embodiment, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a thickness of 0.2 microns to 200 microns. In another embodiment, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a graphene volume fraction of 0.002% to 0.2%. In yet another embodiment, each Cu-Gr layer has a graphene volume fraction of 0.002% to 0.2%. In another embodiment, the central portion includes one of copper and aluminum.

[0009] In another aspect of the present disclosure, another conductive composite material stator unit for a vehicle electric motor is provided. The stator unit includes a stator core, the stator core including a body having a first core end and an opposite second core end, defining a longitudinal axis. The body has an inner radial surface extending from the first core end to the second core end relative to the longitudinal axis. The inner radial surface has a plurality of inner walls extending inwardly from the first core end to the second core end, defining an open slot formed between the respective inner walls from the first core end through the second core end.

[0010] In this regard, the stator unit includes a plurality of conductive bars extending from a first core end to a second core end. Each conductive bar includes a central portion and an outer layer arranged around the central portion for current to flow relative to a longitudinal axis. Each conductive bar includes a straight portion arranged in one of the slots so that the corresponding conductive bar contacts the stator core. Each straight portion has a first radial end located at the first core end and a second radial end located at the second core end. The first radial end extends from the stator core to the first turn portion, and the second radial end extends from the stator core to the second turn portion.

[0011] In this aspect, the outer layer includes at least two copper-graphene (Cu-Gr) layers. Each Cu-Gr layer includes a copper layer and a graphene layer. Each Cu-Gr layer has a graphene volume fraction of 0.002% to 0.2%. In addition, the central portion includes one of copper and aluminum. In addition, the stator unit also includes an insulator layer arranged around each of the plurality of conductive bars.

[0012] In one embodiment, the outer layer also includes a metal substrate having a first side and an opposite second side. The at least two Cu-Gr layers are a first Cu-Gr multilayer composite material disposed on the first side of the metal substrate. The outer layer also includes a second Cu-Gr multilayer composite material disposed on the second side of the metal substrate.

[0013] In another embodiment, the metal substrate has a thickness of 5 microns to 25 microns. In yet another embodiment, the metal substrate comprises one of copper, aluminum, carbon steel, and stainless steel.

[0014] In one embodiment, the second Cu-Gr multilayer composite material includes at least two Cu-Gr layers and includes copper and graphene. In addition, each Cu-Gr layer in the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a thickness of 0.1 micron to 0.5 micron. In another embodiment, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a thickness of 0.2 micron to 200 microns. In another embodiment, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a graphene volume fraction of 0.002% to 0.2%.

[0015] According to another aspect of the present disclosure, another conductive composite material stator unit for a vehicle electric motor is provided. The stator unit includes a stator core, the stator core including a body having a first core end and an opposite second core end, defining a longitudinal axis. The body has an inner radial surface extending from the first core end to the second core end relative to the longitudinal axis. The inner radial surface has a plurality of inner walls extending inwardly from the first core end to the second core end, defining an open slot formed between the respective inner walls from the first core end through the second core end.

[0016] In this regard, the stator unit also includes a plurality of conductive bars extending from the first core end to the second core end. Each conductive bar includes a central portion and an outer layer arranged around the central portion for current to flow relative to the longitudinal axis. The central portion includes one of copper and aluminum. Each conductive bar includes a straight portion arranged in one of the slots so that the corresponding conductive bar contacts the stator core. Each straight portion has a first radial end located at the first core end and a second radial end located at the second core end. The first radial end extends from the stator core to the first turn portion, and the second radial end extends from the stator core to the second turn portion.

[0017] In this regard, the outer layer includes a metal substrate having a first side and an opposite second side. The outer layer includes a first copper-graphene (Cu-Gr) multilayer composite material disposed on the first side of the first metal substrate and a second Cu-Gr multilayer composite material disposed on the second side of the first metal substrate. In addition, the stator unit also includes an insulator layer disposed around each of the plurality of conductive bars.

[0018] In one embodiment, the metal substrate has a thickness of 5 micrometers to 25 micrometers. In addition, the metal substrate includes one of copper, aluminum, carbon steel and stainless steel.

[0019] In another embodiment, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material includes at least two Cu-Gr layers and includes copper and graphene. In addition, each Cu-Gr layer has a thickness of 0.1 micrometer to 0.5 micrometer. In addition, each Cu-Gr layer has a graphene volume fraction of 0.002% to 0.2%.

[0020] In yet another embodiment, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a thickness of 0.2 micrometers to 200 micrometers. In addition, each of the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a graphene volume fraction of 0.002% to 0.2%.

[0021] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0023] Figure 1 is a perspective view of a conductive composite stator unit according to one embodiment of the present invention.

[0024] Figure 2 yes Figure 1 Exploded view of the stator unit in the.

[0025] Figure 3 yes Figure 1 A side cross-sectional view of a conductive bar of a stator unit in FIG.

[0026] Figure 4 yes Figure 1 End view of the conductive rod in FIG.

[0027] Figure 5 is an end view of a circular conductive bar of a stator unit according to another embodiment of the present disclosure.

[0028] Figure 6 According to an implementation scheme Figure 3 Side cross-sectional view of the copper-graphene multilayer composite with conductive rods in it.

[0029] Figure 7is a side cross-sectional view of a copper-graphene multilayer composite material of a conductive bar of a stator unit according to another embodiment of the present disclosure.

[0030] Figure 8 According to one embodiment of the present disclosure Figure 1 Partial view of the inner radial surface and the conductive bars of the stator unit being assembled.

[0031] Fig. 9 yes Figure 8 A partial view of the inner radial surface and the conductive rod in the contact for welding the conductive rod.

[0032] Fig.10 yes Fig. 9 A partial view of the inner radial surface and the conductive rod when the conductive rod is welded. DETAILED DESCRIPTION

[0033] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0034] Embodiments of the present disclosure provide a conductive composite material stator unit for a vehicle motor. The stator unit includes a stator core and a plurality of conductive rods disposed within the stator core. Each conductive rod includes a central portion (such as copper or aluminum), and an outer layer is disposed around the central portion for current to flow operably. The outer layer includes at least two layers of copper-graphene (Cu-Gr) layers. The application of the outer layer provides a conductivity advantage due to the "skin effect" of electron transport. That is, the skin effect is a phenomenon in which an alternating current flows unevenly relative to the cross-section of a conductive element (such as a conductive rod). The current density of a conductive element or conductive rod is highest near its surface and decreases exponentially with increasing distance from the surface. Therefore, when a Cu-Gr layer is coated or bonded around the conductive rod, the advantage of the relatively high conductivity of the Cu-Gr layer can be utilized due to the skin effect of electron transport in high-frequency applications.

[0035] Figure 1 A conductive composite stator unit 10 for a vehicle electric motor according to one embodiment of the present disclosure is shown. As shown, the stator unit 10 includes a stator core 12. In this embodiment, the stator core 12 includes a body 14 having a first core end 16 and an opposite second core end 18, defining a longitudinal axis. In addition, the body 14 has an inner radial surface 20 extending from the first core end 16 to the second core end 18 relative to the longitudinal axis. Figure 1 As shown, the inner radial surface 20 has a plurality of inner walls 22 extending inwardly from the first core end 16 to the second core end 18, defining open slots 24 formed between the respective inner walls 22. That is, the open slots 24 extend from the first core end 16 through the second core end 18 between the respective inner walls 22.

[0036] Reference Figure 1-2 The stator unit 10 also includes a plurality of winding conductive bars / wires 30 extending from the first core end 16 to the second core end 18 of the stator core 12. As further described below, each conductive bar 30 has a winding portion at each of its opposite ends. In addition, the conductive bar 30 can have a flat, rectangular ( Figure 4 ) or round ( Figure 5 ) cross-sectional shape, and can be used in motors, transformers, generators and electrical measuring instruments. Other suitable shapes of conductive rods 30 may be used without departing from the spirit or scope of the present disclosure.

[0037] like Figure 1-2 As shown, each conductive bar 30 includes a straight portion 32 disposed in one of the slots (in Figure 1 1 and 12 ) so that the corresponding conductive bars 30 are in contact with the stator core 12. In this embodiment, each straight portion 32 has a first radial end 34 located at the first core end 16 and a second radial end 36 located at the second core end 18. The first radial end 34 extends from the stator core 12 to the first turn portion 40 (winding portion), and the second radial end 36 extends from the stator core 12 to the second turn portion 42 (winding portion).

[0038] Reference Figure 3-4 Each conductive rod 30 includes a central portion 50 and an outer layer 52 disposed around the central portion 50 for current to flow relative to the longitudinal axis. The outer layer 52 includes at least two copper-graphene (Cu-Gr) layers. Each Cu-Gr layer 54 includes a copper layer 56 and a graphene layer 58. In addition, the central portion 50 includes one of copper and aluminum.

[0039] like Figure 3-4As shown, the stator unit 10 also includes an insulator layer 60 disposed around each of the plurality of winding conductive bars 30. In one embodiment, the insulator layer 60 is a wire enamel. The wire enamel can be applied to a copper or aluminum conductive bar / wire 30. Without departing from the spirit or scope of the present disclosure, the wire enamel can be cured and applied to the conductive bar / wire 30 using heat or by any other suitable means. The main function of the resulting coating is electrical insulation. The wire enamel can be applied to the conductive bar 30 in up to 30 layers. Such application provides electrical insulation and helps the winding portion of the conductive bar 30 to avoid short circuits. In addition, the wire enamel is composed of a material that is chemically and heat resistant and provides adhesion and mechanical stability to the copper or aluminum conductive bar / wire 30. That is, without departing from the spirit or scope of the present disclosure, the wire enamel may be composed of polyurethane (PUR), weldable polyester imide (PEI), THEIC modified polyester (TPE), THEIC-polyesterimide (TPEI), polyamide-imide (PAI), polyvinyl formal (PVF), self-bonding (SB) material (based on epoxy resin, polyvinyl butyral and polyamide), or any other suitable material.

[0040] Figure 5 Conductive wire 130 is depicted as having a circular cross-sectional shape. Aside from its cross-sectional shape, conductive wire 130 is similar to conductive rod 30 described above. As shown, outer layer 152 is disposed around central portion 150, and insulator layer 160 is coated around outer layer 152.

[0041] Figure 6 The cross section of the outer layer 52 of the conductive rod 30 is shown. As shown, the outer layer 52 may include at least two Cu-Gr layers 54, wherein each Cu-Gr layer 54 includes copper and graphene. Preferably, each Cu-Gr layer 54 includes a copper layer 56 and a graphene layer 58.

[0042] It should be understood that the outer layer 52 of this embodiment may include a multilayer Cu-Gr layer 54, including 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 250, 300, 350, 400, 450 and more than 500 layers of Cu-Gr layers. In addition, each Cu-Gr layer 54 has a thickness of 0.1 micron to 0.5 micron. Preferably, each Cu-Gr layer 54 can have a thickness of 0.2 micron, 0.3 micron and 0.4 micron. In one embodiment, each Cu-Gr layer 54 has a graphene volume fraction of 0.002% to 0.2%. Preferably, each Cu—Gr layer 54 may have a graphene volume fraction of 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.011%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.05%, 0.075%, 0.1%, 0.125%, 0.15% and 0.175%.

[0043] It should be understood that each of the Cu-Gr layers 54 can be manufactured in any suitable manner without departing from the spirit or scope of the present disclosure. For example, a graphene layer can be modulated on a first copper layer using chemical vapor deposition (CVD) or physical vapor deposition (PVD), thereby disposing the graphene layer on the first copper layer. Electron beam deposition (EBD) can be used to modulate a second copper layer on the graphene layer. Then, on the second copper layer, alternating graphene layers and copper layers can be modulated thereon by CVD and EBD, respectively. Other ways of manufacturing the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material can be implemented without departing from the spirit or scope of the present disclosure.

[0044] In this embodiment, the outer layer 52 has a thickness of 0.2 microns to greater than 200 microns. Preferably, the outer layer 52 may have a thickness of 0.3 microns, 0.4 microns, 0.5 microns, 1.0 microns, 1.5 microns, 2.0 microns, 2.5 microns, 3.0 microns, 3.5 microns, 4.0 microns, 4.5 microns, 5.0 microns, 5.5 microns, 6.0 microns, 6.5 microns, 7.0 microns, 7.5 microns, 8.0 microns, 8.5 microns, 9.0 microns, 9.5 microns, 10 microns, 25 microns, 50 microns, 75 microns, 100 microns, 125 microns, 150 microns, 175 microns, 225 microns, 250 microns, 300 microns, 400 microns, 500 microns and 550 microns or more. Preferably, the outer layer 52 may have a graphene volume fraction of 0.002% to 3%. In addition, the outer layer 52 can have a graphene volume fraction of 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.011%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.05%, 0.075%, 0.1%, 0.125%, 0.15% and 0.175%, 0.25%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5% or more.

[0045] Figure 7 A cross section of an outer layer 252 of a conductive rod (not shown, but similar to the conductive rod 30 described above) according to another embodiment of the present disclosure is shown. As shown, the outer layer 252 includes a metal substrate 253 (e.g., a metal foil such as a copper foil) having a first side 255 and an opposite second side 257. In one embodiment, the metal substrate 253 has a thickness of 5 microns to 25 microns. Preferably, the metal substrate 253 may have a thickness of 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, 20 microns, 21 microns, 22 microns, 23 microns, and 24 microns. In addition, the metal substrate 253 may include one of copper, aluminum, carbon steel, and stainless steel.

[0046] like Figure 7As shown, the outer layer 252 also includes a first copper-graphene (Cu-Gr) multilayer composite material 262 disposed on a first side 255 of the metal substrate 253 by any suitable means and a second Cu-Gr multilayer composite material 264 disposed on a second side 257 of the metal substrate 253. In addition, each of the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 includes at least two Cu-Gr layers 254, preferably six or more Cu-Gr layers 254. Each of the Cu-Gr layers 254 includes copper and graphene. Preferably, each of the Cu-Gr layers includes a copper layer 256 and a graphene layer 258. It should be understood that the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 may include multiple Cu-Gr layers 254, including 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 Cu-Gr layers or more layers.

[0047] In addition, each Cu-Gr layer 254 of the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 includes copper and graphene and has a thickness of 0.1 micrometer to 0.5 micrometer. Preferably, each Cu-Gr layer 254 may have a thickness of 0.2 micrometer, 0.3 micrometer, and 0.4 micrometer. In addition, each of the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 has a thickness of 0.2 micrometer to 200 micrometers, preferably 1.3 micrometers. Preferably, each of the first multilayer composite material 262 and the second multilayer composite material 264 may have a thickness of 0.3 microns, 0.4 microns, 0.5 microns, 1.0 microns, 1.5 microns, 2.0 microns, 2.5 microns, 3.0 microns, 3.5 microns, 4.0 microns, 4.5 microns, 5.0 microns, 5.5 microns, 6.0 microns, 6.5 microns, 7.0 microns, 7.5 microns, 8.0 microns, 8.5 microns, 9.0 microns, 9.5 microns, 10 microns, 25 microns, 50 microns, 75 microns, 100 microns, 125 microns, 150 microns and 175 microns.

[0048] In addition, each of the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 has a graphene volume fraction of 0.002% to 0.2%. Preferably, each of the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 may have a graphene volume fraction of 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.011%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.05%, 0.075%, 0.1%, 0.125%, 0.15% and 0.175%.

[0049] It should be understood that each of the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 can be manufactured by any suitable method without departing from the spirit or scope of the present disclosure. For example, the Cu-Gr layer 254 can be disposed on the metal substrate 253 by modulating a graphene layer 258 on the metal substrate 253 using chemical vapor deposition (CVD) or physical vapor deposition (PVD) and modulating a copper layer 256 on the graphene layer using electron beam deposition (EBD). Then, on the copper layer, alternating graphene layers 258 and copper layers 256 can be modulated thereon by CVD and EBD, respectively. Other methods of manufacturing the first Cu-Gr multilayer composite material 262 and the second Cu-Gr multilayer composite material 264 can be implemented without departing from the spirit or scope of the present disclosure.

[0050] In assembling the stator unit 10, Figure 8 Conductive bars 30 are shown, each of which has been formed and disposed through an open slot 24 between respective inner walls 22 on the inner radial surface 20 of the stator core 12 for assembly of the stator unit 10. In this embodiment, each conductive bar 30 includes a free end 31 disposed adjacent the second core end 18 of the stator core 12. As shown, such free ends 31 extend longitudinally through the first core end 16 in the open slot 24 and meet at a point 33. The forming and disposition of the conductive bars 30 in the open slot 24 may be accomplished by any suitable mechanical means (e.g., a mechanical mechanism) without departing from the spirit or scope of the present disclosure.

[0051] like Fig. 9 As shown, adjacent free ends may be heat twisted or connected in preparation for welding, thereby defining a connection end 35. Contacting and connecting adjacent free ends 31 may be accomplished by any suitable mechanical system, such as a gripping system with a robotic arm, without departing from the spirit or scope of the present disclosure.

[0052] Reference Fig.10, the connection ends 35 may be welded together to define a welded end 37 of the conductive bar 30. The welded connection ends may be achieved by any suitable welding mechanism without departing from the spirit or scope of the present disclosure.

[0053] The description of the present disclosure is merely exemplary in nature, and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations should not be regarded as departing from the spirit and scope of the present disclosure.

Claims

1. A conductive composite material stator unit for a vehicle motor, the stator unit comprising: a stator core, the stator core comprising a body having a first core end and an opposite second core end, defining a longitudinal axis, the body having an inner radial surface extending from the first core end to the second core end relative to the longitudinal axis, the inner radial surface having a plurality of inner walls extending inwardly from the first core end to the second core end, defining an open slot formed between the respective inner walls from the first core end through the second core end; a plurality of conductive bars extending from the first core end to the second core end, each conductive bar comprising a central portion and an outer layer disposed around the central portion for current to flow relative to the longitudinal axis, each conductive bar comprising a straight portion disposed in one of the slots so that the corresponding conductive bar contacts the stator core, each straight portion having a first radial end located at the first core end and a second radial end located at the second core end, the first radial end extending from the stator core to a first turn portion, and the second radial end extending from the stator core to a second turn portion, the outer layer comprising at least two copper-graphene (Cu-Gr) layers, each Cu-Gr layer comprising a copper layer and a graphene layer; as well as An insulator layer is disposed around each of the plurality of conductive bars.

2. The stator unit according to claim 1, wherein: The outer layer also includes a metal substrate having a first side and an opposite second side, the at least two Cu-Gr layers are a first Cu-Gr multilayer composite material arranged on the first side of the metal substrate, and the outer layer also includes a second Cu-Gr multilayer composite material arranged on the second side of the metal substrate.

3. The stator unit according to claim 2, wherein: The metal substrate has a thickness of 5 micrometers to 25 micrometers.

4. The stator unit according to claim 2, wherein: The metal substrate includes one of copper, aluminum, carbon steel and stainless steel.

5. The stator unit according to claim 2, wherein: The second Cu-Gr multilayer composite material includes at least two Cu-Gr layers and includes copper and graphene, and wherein each Cu-Gr layer in the first Cu-Gr multilayer composite material and the second Cu-Gr multilayer composite material has a thickness of 0.1 micrometer to 0.5 micrometer.

6. The stator unit according to claim 2, wherein: Each of the first Cu—Gr multi-layer composite material and the second Cu—Gr multi-layer composite material has a thickness of 0.2 micrometers to 200 micrometers.

7. The stator unit according to claim 2, wherein: Each of the first Cu—Gr multi-layer composite material and the second Cu—Gr multi-layer composite material has a graphene volume fraction of 0.002% to 0.2%.

8. The stator unit according to claim 1, wherein: Each Cu—Gr layer has a graphene volume fraction of 0.002% to 0.2%.

9. The stator unit according to claim 1, wherein: The center portion includes one of copper and aluminum.

Images