Highly conductive composite stator winding bundle with enhanced skin effect in electric motors

Abstract

A composite harness for a stator winding, a stator including the composite harness, and a method of forming the composite harness. The composite wire harness includes a plurality of copper wires, where each of the plurality of copper wires includes a first surface. The composite wire harness further comprises a copper-graphene multilayer composite material coated on the first surface of each copper wire in the plurality of copper wires, and the copper-graphene multilayer composite material comprises a second surface. Further, the composite wire harness includes a fluoropolymer matrix formed around the second surface and a sheath encapsulating the fluoropolymer matrix.

Description

Background Art

[0001] Electric and hybrid electric vehicle technology is made possible by the development and use of rechargeable secondary batteries. Rechargeable secondary batteries provide energy to the electric traction motors, servo motors, and other electronic devices in the vehicle. The traction motor includes a fixed stator and a rotor rotatably positioned inside the stator. The stator may include coil windings wrapped around teeth in the stator. When alternating current (AC) is passed through the stator, the windings generate a magnetic field, and the permanent magnets in the rotor attempt to align with the magnetic field, causing the rotor to rotate inside the stator.

[0002] However, in alternating current (AC) power distribution, the current density tends to be greater near the surface of the conductor (such as the windings and busbars of the stator) and decreases as it approaches the core of the conductor. This effectively reduces the cross-section of the larger conductor and increases the effective resistance. This effect is called the skin effect and increases as the frequency of the AC increases. To combat this effect, several smaller conductors are usually used instead of one large conductor. Each of the smaller conductors has a smaller cross-sectional area than the large conductor, but together they can have a similar cross-sectional area as the large conductor.

[0003] Therefore, while existing wire harnesses in traction motors perform their intended purpose, a need exists for new and improved wire harnesses in traction motors. Summary of the invention

[0004] According to several aspects, the present disclosure relates to a composite wire harness for a stator winding. The composite wire harness includes a plurality of copper wires, wherein each of the plurality of copper wires includes a first surface. The composite wire harness also includes a copper-graphene multilayer composite material coated on the first surface of each of the plurality of copper wires, wherein the copper-graphene multilayer composite material includes a second surface. Further, the composite wire harness includes a fluoropolymer matrix formed around the second surface and a sheath encapsulating the fluoropolymer matrix.

[0005] In an embodiment, each of the plurality of copper wires has a diameter in a range of 0.3 mm to 10 mm.

[0006] In any of the above embodiments, the copper included in the copper-graphene multilayer composite material is oxidized at the second surface. In a further embodiment, the oxidized copper in the second surface has a thickness in the range of 5 micrometers to 15 micrometers.

[0007] In any of the above embodiments, the copper-graphene multilayer composite material has an electrical conductivity in a range of 105% to 400% of the International Annealed Copper Standard (IACS).

[0008] In any of the above embodiments, the copper-graphene multilayer composite material has a thickness in a range from 10 nanometers to 500 micrometers.

[0009] In any of the above embodiments, the copper-graphene multilayer composite material includes a plurality of alternating layers of graphene and copper.

[0010] In any of the above embodiments, the copper-graphene multilayer composite material includes graphene particles dispersed between a plurality of coated thin copper layers.

[0011] In any of the above embodiments, the fluoropolymer includes polytetrafluoroethylene.

[0012] In any of the above embodiments, the jacket comprises a polymer. In further embodiments, the polymer comprises at least one of the following polymers: polyetherimide (PEI), polyetheretherketone (PEEK), polyimide (PI), polyamideimide (PAI), or an epoxy resin formed by polymerization of an epoxide. In still other embodiments, the jacket comprises a plurality of polymer layers.

[0013] In any of the above embodiments, the copper included in the copper-graphene multilayer composite material at the second surface is oxidized at the second surface, the wire comprises copper, the fluoropolymer matrix comprises polytetrafluoroethylene, and the jacket comprises a polymer.

[0014] In any of the above embodiments, the composite wire harness is wound around the plurality of teeth and held in a plurality of channels defined between the plurality of teeth in the stator core. In further embodiments, the composite wire harness is connected to a bus bar. In still other embodiments, the bus bar is connected to an inverter.

[0015] According to another aspect, the present disclosure relates to a stator for a vehicle including a composite wiring harness. The stator includes: a stator core including a plurality of channels defined by a plurality of teeth; and a composite wiring harness according to any of the above embodiments received in the plurality of channels. The composite wiring harness includes a plurality of copper wires, wherein each of the plurality of copper wires includes a first surface; a copper-graphene multilayer composite material coated on the first surface of each of the plurality of copper wires, wherein the copper-graphene multilayer composite material includes a second surface, copper oxidation at the second surface; a fluoropolymer matrix formed around the oxidized copper surface; and a sheath encapsulating the plurality of fluoropolymer matrices.

[0016] According to yet another aspect, the present disclosure relates to a method for forming a composite wire harness for a stator. The method includes: oxidizing the copper of a first surface of a copper-graphene multilayer composite material formed on a second surface of each of a plurality of copper wires; coating a fluoropolymer on the first surface of the copper-graphene multilayer composite material formed on each of a plurality of wires, curing the fluoropolymer, consolidating a plurality of copper wires, and forming a fluoropolymer matrix with the coated fluoropolymer, wherein the fluoropolymer matrix surrounds the second surface and forms a sheath around the fluoropolymer matrix.

[0017] In the above embodiment, the method further includes oxidizing copper included in the first surface of the copper-graphene multi-layer composite material before coating the fluoropolymer.

[0018] In any of the above embodiments, the method further includes annealing the copper wire while curing the fluoropolymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0020] Figure 1 A vehicle including a propulsion system utilizing an electric traction motor according to various embodiments of the present disclosure is shown;

[0021] Figure 2A A traction motor stator according to various embodiments of the present disclosure is shown;

[0022] Figure 2B shows a stator core according to various embodiments of the present disclosure;

[0023] Figure 3A shows a cross-sectional view along the axis of a composite conductor according to various embodiments of the present disclosure;

[0024] Figure 3B The vertical direction according to various embodiments of the present disclosure is shown. Figure 3A A cross-sectional view of the axis of a copper conductor;

[0025] Figure 3C The vertical direction according to various embodiments of the present disclosure is shown. Figure 3A A cross-sectional view of the axis of a bundle of copper conductors;

[0026] Figure 4A shows a cross-sectional view along the axis of a composite conductor according to various embodiments of the present disclosure;

[0027] Figure 4B The vertical direction according to various embodiments of the present disclosure is shown. Figure 4A A cross-sectional view of the axis of a copper conductor;

[0028] Figure 4C The vertical direction according to various embodiments of the present disclosure is shown. Figure 4A A cross-sectional view of the axis of a bundle of copper conductors;

[0029] Figure 5A shows a cross-sectional view along the axis of a composite conductor according to various embodiments of the present disclosure;

[0030] Figure 5B The vertical direction according to various embodiments of the present disclosure is shown. Figure 5AA cross-sectional view of the axis of a copper conductor;

[0031] Figure 5C The vertical direction according to various embodiments of the present disclosure is shown. Figure 5A A cross-sectional view of the axis of a bundle of copper conductors;

[0032] Figure 6 A method of forming a conductive tape according to various embodiments of the present disclosure is shown; and

[0033] Figure 7 A schematic diagram of a bundling process according to various embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0034] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application or use. In addition, there is no intention to be bound by any express or implied theory presented in the foregoing background technology, summary of the invention, or the following detailed description. It should be understood that throughout the drawings, corresponding reference numerals indicate similar or corresponding parts and features.

[0035] Reference will now be made in detail to several examples of the present disclosure illustrated in the accompanying drawings. Whenever possible, the same or similar reference numerals are used in the drawings and description to refer to the same or similar components or steps. The drawings are in simplified form and are not to exact scale.

[0036] The present disclosure relates to a composite winding bundle for use in a stator, a stator including the composite winding bundle for use in a vehicle, and a method of forming a composite stator winding bundle for use in a vehicle.

[0037] As used herein, the term "vehicle" is not limited to automobiles. Although the present technology is described primarily in conjunction with electric vehicles herein, the present technology is not limited to electric vehicles and may also be hybrid electric vehicles. In addition, these concepts can be used in a variety of applications, such as in conjunction with components used in motorcycles, mopeds, locomotives, aircraft, ships, and other vehicles, and in other applications utilizing batteries, such as portable power stations (e.g., portable power stations for powering remote work locations and emergency backup power, as well as permanent power stations associated with buildings and equipment), all of which can be powered by, for example, solar or wind turbine generator systems, power mains, and fuel-based generators (e.g., gasoline or diesel generators and Stirling engines).

[0038] Figure 1A vehicle 100 is shown that includes a propulsion system 120. The propulsion system 120 typically includes an electric motor 124 and a secondary battery 126 for powering the electric motor 124. Further, in many embodiments of the propulsion system 120, the propulsion system 120 includes an inverter 128 for changing power from DC (direct current) provided by the battery 126 to AC (alternating current) used by the electric motor 124. The inverter 128 may be included in a power electronics module 130 that includes, for example, transistors and diodes for switching power from DC to AC and vice versa. In an embodiment, the battery is connected to the electric motor through the power electronics module.

[0039] A controller 132 may also be included in or otherwise connected to the power electronics module 130, connected to the inverter 128 and programmed to control and manage the operation of the motor 124 and associated hardware, including the inverter 128. The motor 124 is connected to a transmission (drive unit) 136 and a drive train 138, which transmit mechanical power and rotation to wheels 140 of the vehicle 100. The controller 132 includes one or more processors and tangible, non-transitory memory 134.

[0040] Referring again to the motor 124, the motor 124 powered by the battery 126 includes a stator 142 and a rotor 144 rotatably arranged inside the stator 142. The stator 142 is a fixed portion of the motor 124. When alternating current (AC) is applied, the stator 142 provides a rotating magnetic field, and the fixed magnetic field of the rotor 144 attempts to align with the rotating magnetic field, causing the rotor 144 to rotate, which can be referred to as a "motor drive" mode. In traction electric vehicle applications, the motor drive mode provides propulsion to the vehicle 100. In other applications, the rotating field of the rotor 144 (caused by physical rotation) generates current in the stator 142-this mode of operation is called "generation" and the motor 124 used in this way is used as a generator. The power generation mode captures some of the energy recovered from braking, for example, when the vehicle is in the process of decelerating and stopping, and stores it back in the battery 126.

[0041] refer to Figure 2A and 2B , Figure 2A and 2B An example of a stator 142 is shown. The stator 142 may generally include a plurality of wire windings 148 extending along a length L of the stator 142. The wire windings 148 are connected to one or more bus bars 150 that connect the wire windings 148 to the inverter 128 and the battery 126 in the power electronics module 130. The wire windings 148 are wound around a plurality of teeth 154 that protrude from a core 152 of the stator 142, such as Figure 2BA plurality of channels 156 are defined between the teeth 154 for receiving the wire windings 148. As shown, the core 152 has a cylindrical geometry, and the teeth 154 protrude into the opening defined by the stator 142. In an alternative embodiment, the teeth 154 may protrude from the outer surface of the core 152.

[0042] In an embodiment, the wire windings 148 are formed from a composite wire bundle 160 , such as Figures 3A to 5C The composite wire harness 160, such as Figure 3C , 4C and those shown in 5C, including a plurality of copper wires 162. Although reference is made herein to copper wires, alternatively, the wires may be any material formed of a conductive material having a thermal conductivity of at least 1x10 7 Siemens per meter (S / m) conductivity, for example in 1x10 7 S / m (20 degrees Celsius) to 6.3x10 7 S / m (20 degrees Celsius). Therefore, in alternative embodiments, the wire material includes steel, aluminum, aluminum alloys and copper alloys. The copper wire 162 may each have a thickness or diameter in the range of 0.3 mm to 10 mm, including all values ​​and ranges therein, such as 0.5 mm to 5 mm. Further, as Figure 3B , 4B 5B, the copper wire 162 has any number of cross-sections, including square ( Figure 3B ),hexagon( Figure 4B ) and round ( Figure 5B ), as shown, as well as rectangular, oval, elliptical, pentagonal, etc. Further, the wire may include a foil or trace deposited on a substrate. The foil may contain a copper-graphene multilayer coated on its surface and then wrapped around a copper strip or copper wire. It should be understood that the wires mentioned herein may be replaced by other conductors that can be used to conduct electricity in a vehicle.

[0043] Each of the copper wires 162 includes a surface 164, such as Figure 3A , 3B, 4A, 4B, 5A, 5B, a copper-graphene multilayer composite material 166 is formed on the surface 164 of each of the copper wires 162. In an embodiment, the copper-graphene multilayer composite material 166 has an electrical conductivity in the range of 105% to 400% of the International Annealed Copper Standard (IACS), including all values ​​and ranges therein. The International Annealed Copper Standard (IACS) is understood as a percentage of the electrical conductivity of a material relative to copper, with copper being considered to be 100% conductive and having a resistivity of 1.7241 micro-ohm-cm at a reference of 20 degrees Celsius. In an embodiment, the copper-graphene multilayer composite material 166 includes one or more alternating layers of copper and graphene deposited on the copper wire 162. In such an embodiment, graphene is first deposited on each copper wire 162, then copper is deposited on the graphene, and the process is repeated until there is a desired number of layers. In an additional or alternative embodiment, graphene particles are dispersed between multiple coated copper layers. In some other embodiments described above, copper and graphene can be deposited onto copper foil as alternating layers of copper and graphene or with graphene particles in a copper matrix, which can then be wrapped around the copper wire 162. The copper-graphene multilayer composite material in any of the above embodiments can be directly applied to the copper wire 162 or to the copper foil wrapped around the copper wire 162 using one of several techniques such as electrochemical deposition, electrodeposition, physical vapor deposition, chemical vapor deposition, and layer-by-layer assembly. The copper-graphene multilayer composite material 166 can have a thickness in the range of 10 nanometers to 500 microns, including all values ​​and ranges therein, such as in the range of 30 microns to 300 microns. When a foil is present, the foil has a thickness in the range of 5 microns to 25 microns, including all values ​​and ranges therein, in addition to the remaining copper-graphene multilayer composite material.

[0044] In addition, in any of the above embodiments, the copper at the surface 168 of the copper-graphene multilayer composite material 166 is oxidized to form copper oxide including a mixture of cuprous oxide (CuO) and cupric oxide (Cu2O). The copper oxide is an electrical insulator, providing an insulating layer around each copper wire 162. As understood herein, an electrical insulator is an electrical insulator having a relative humidity of less than 1.0×10 3 The material has an electrical conductivity of siemens per meter. The copper oxide at the surface 168 can have a thickness in the range of 5 nanometers to 15 micrometers, including all values ​​and ranges therein, for example 10 micrometers.

[0045] Fluoropolymer matrix 170, such as Figure 3C , 4C5C, formed on the surface of the copper oxide surface 168 of the copper-graphene multilayer composite material 166. The fluoropolymer matrix 170 can initially be applied to each wire 162 as a fluoropolymer coating. In an embodiment, the fluoropolymer coating has a thickness in the range of 0.1 microns to 500 microns, including all values ​​and ranges therein. The copper wires 162 are then bundled together, and the fluoropolymer coating on each copper wire 162 is heated and consolidated to form the fluoropolymer matrix 170, as further described herein. In an embodiment, the fluoropolymer includes polytetrafluoroethylene (PTFE) or polyfluoroalkoxyalkane (PFA), for example, with a tensile strength of 21 megapascals (MPa) to 34 MPa, an elongation of 300% to 500%, and a folding endurance of more than one million cycles, allowing the harness 174 to be relatively easily deformed.

[0046] One or more layers of sheath 172 are disposed on the fluoropolymer matrix 170 of the bundled copper wires 162 to form the composite wire bundle 160. In an embodiment, the sheath 172 comprises a polymer. Suitable polymers include, for example, polyetherimide (PEI), polyetheretherketone (PEEK), polyimide (PI), polyamideimide (PAI), or epoxy resins formed by polymerization of epoxides. When multiple layers of sheath 172 are present, each layer can be formed of the same or different materials.

[0047] In various embodiments, the composite wiring harness 160 uses a Figure 6 and 7 6 and 700 described in the invention. At block 602, the surface 168 of the copper-graphite multilayer composite material 166 is oxidized. The oxidation occurs in a heating environment 702, such as a furnace, which is heated at a temperature in the range of 425 degrees Celsius to 475 degrees Celsius, including all values ​​and ranges therein, such as 445 degrees Celsius to 455 degrees Celsius. The heating environment 702 includes oxygen. In an embodiment, the heating environment 702 includes air. The heating of the surface 168 of the copper-graphite multilayer composite material 166 may occur for a first time period in the range of 1 hour to 10 hours, including all values ​​and ranges therein, such as from 300 minutes to 420 minutes.

[0048] Once the surface 168 of the copper-graphene multilayer composite material 166 is oxidized, one of the above-mentioned fluoropolymers is applied as a coating to the oxidized surface 168 in frame 604. In an embodiment, the copper-graphene multilayer composite material 166 coated with the outer surface oxidation of the copper wire 162 is cooled to a second temperature below the melting temperature of the fluoropolymer sprayed on the oxidized surface, for example, in the range of 20 degrees Celsius to 250 degrees Celsius, including all values ​​and ranges therein, for example, from 20 degrees Celsius to 200 degrees Celsius. Melting temperature is understood herein as a temperature at which a polymer material (e.g., fluoropolymer) begins to melt and become viscous due to the increase in atomic motion at the submolecular and molecular levels under a given pressure. Fluoropolymers are coated using one of the following processes 704, including spraying, air atomization spraying, dip spin coating, or electrostatic coating with a sprayer. In such a process, fluoropolymers can be dispersed in a solvent, such as trichlorotrifluoroethane or other halogenated hydrocarbons with a boiling point below 60 degrees Celsius at standard pressure (20 degrees Celsius). Alternatively, the fluoropolymer is coated in a fluidized bed, wherein the oxidized copper-graphene multilayer composite 166 coated copper wire 162 can be heated at a first temperature equal to or higher than the temperature of the fluoropolymer while in the furnace 702 and transferred to a fluidized bed containing a powdered fluoropolymer agitated with air or another gas. As the wire 162 passes through the fluidized bed, the fluoropolymer powder adheres to the oxidized surface 168 of the preheated wire 162. In an embodiment, the fluoropolymer coating is relatively uniformly coated on the oxidized surface 168 by mass.

[0049] At box 606, the copper wires 162 including the fluoropolymer coating are formed into a bundle 174 by curing the fluoropolymer coating and consolidating the copper wires 162 together. To consolidate the copper wires 162, the copper wires 162 are pushed or squeezed by passing the copper wires 162 together through a heated die 706. The die 706 forces the fluoropolymer coating applied to the surface of the copper wires 162 coated with the oxidized copper-graphene multilayer composite material 166 to flow around the oxidized surface 168 of the copper wires 162 and form a fluoropolymer matrix 170, thereby bonding the copper wires 162 together. In an embodiment, the bundle 174 can be a coherent bundle, wherein the copper wires 162 are located at the same relative position at the beginning and end of the bundle 174. In an embodiment, the die 706 is heated to a consolidation temperature in the range of 375°C to 400°C, including all values ​​and ranges therein. The consolidation temperature is understood to be a temperature that allows the fluoropolymer to deform and flow, and in an embodiment, the consolidation temperature is high enough to anneal the copper wires 162. Further, the copper wire 162 coated with the copper oxide-graphene multilayer composite 166 having an outer surface coated with a fluoropolymer has a residence time in the die of 0.2 milliseconds to 1 millisecond, including all values ​​and ranges therein, to allow the fluoropolymer to flow and consolidate into the fluoropolymer matrix 170. In an embodiment, the die length can be in the range of 10 mm to 100 mm, including all values ​​and ranges therein, and the speed at which the wire is drawn through the die can be in the range of 1 mm per second to 100 meters per second, including all values ​​and ranges therein. In addition, as mentioned, the residence time and consolidation temperature recrystallize and anneal the copper wire 162. Annealing of the copper in the copper wire 162 can help reduce the brittleness of the wire and increase the electrical conductivity of the wire.

[0050] At block 608, the bundle 174 is then coated with a jacket 172 that provides electrical insulation for the bundle 174. The jacket 172 comprises a polymer. In an embodiment, the polymer comprises polyetherimide (PEI), polyetheretherketone (PEEK), polyimide (PI), polyamideimide (PAI), or an epoxy resin formed by polymerization of an epoxide. The jacket 172 is applied using one of a variety of processes including stretching the bundle 174 through one or more dies 708 (e.g., an extrusion die), and the polymer is extruded onto the bundle 174. The die 708 may be formed to accommodate any convex or concave curve in the bundle 174. In an embodiment, multiple layers of the jacket 172 may be applied. The resulting wiring harness is a composite wiring harness 160 including a plurality of copper wires, wherein each of the plurality of copper wires includes a surface; a copper-graphene multilayer composite material formed on the surface of the copper wire, wherein the exterior of the copper-graphene multilayer composite material is oxidized, a fluoropolymer coating is formed on the copper-graphene multilayer composite material, the fluoropolymer coating forming a matrix around the copper wire; and a sheath encapsulating the plurality of copper wires and the fluoropolymer coating.

[0051] In an embodiment, the composite wire bundle 160 is then used to form the windings 148 of the stator 142. The composite wire bundle 160 is wrapped around the teeth 154 of the stator 142 and inserted into the channels 156. The windings 148 may then be secured to the busbars 150 and connected to other components in the propulsion system, such as the inverter 128.

[0052] The composite winding bundle for stator, the stator including the composite winding bundle for vehicle and the method for forming the composite stator winding bundle for vehicle described herein provide many advantages. These advantages include the increase of wire insulation between single copper wires due to oxidation of the outer copper-graphene layer of the copper-graphene multilayer coating and the inclusion of a fluoropolymer matrix between the wires. In addition, the bundle sheath provides insulation. Advantages also include increasing the conductivity by using the skin effect by providing multiple smaller wires (rather than a single wire of the same cross-sectional area), thereby producing a larger skin area. Further, the area of ​​the copper-graphene multilayer composite material increases and the conductivity also increases. These advantages also include improved magnetic field generation, which can increase the torque generated and the efficiency of the motor. These advantages also include providing electrical insulation for the wire harness. In addition, these advantages include improvements in high-frequency applications, such as in the range of 1 kilohertz to tens of kilohertz, where the skin effect increases, such as high-speed motors. These advantages also include reducing energy losses.

[0053] As used herein, the term "controller" and related terms such as microcontroller, control module, module, controller, control unit, processor and similar terms refer to one or more combinations of application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), electronic circuits, central processing units, such as microprocessors, and related non-transitory memory components in the form of memory and storage devices (read-only, programmable read-only, random access, hard drives, etc.). The controller 132 can also be composed of multiple controllers that are electrically connected to each other. The controller 132 can be interconnected with additional systems and / or controllers of the vehicle 100, allowing the controller 132 to access data such as the speed, acceleration, braking, and steering angle of the vehicle 100.

[0054] The processor may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with the controller 132, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally a device for executing instructions.

[0055] The tangible non-transitory memory 134 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the processor is powered off. The tangible non-transitory memory 134 may be implemented using a plurality of memory devices, such as PROM (programmable read-only memory), EPROM (electrical PROM), EEPROM (electrically erasable PROM), flash memory, or other electrical, magnetic, optical, or combination memory devices capable of storing data, some of which represent various system executable instructions used by the controller 132 to control the vehicle 100.

[0056] 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 fall 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 composite wire harness for stator winding, comprising: a plurality of copper wires, wherein each of the plurality of copper wires comprises a first surface; a copper-graphene multilayer composite material applied to the first surface of each of the plurality of copper wires, wherein the copper-graphene multilayer composite material comprises a second surface; a fluoropolymer matrix formed around the second surface; and A sheath encapsulating the fluoropolymer matrix.

2. The composite wire harness according to claim 1, wherein: Each of the plurality of copper wires has a diameter in a range of 0.3 mm to 10 mm.

3. The composite wire harness according to claim 1, wherein: Copper included in the copper-graphene multi-layer composite material is oxidized at the second surface.

4. The composite wire harness according to claim 3, wherein: The copper oxide in the second surface has a thickness in a range of 5 micrometers to 15 micrometers.

5. The composite wire harness according to claim 1, wherein: The copper-graphene multilayer composite material has an electrical conductivity in the range of 105% to 400% of the International Annealed Copper Standard IACS.

6. The composite wire harness according to claim 1, wherein: The copper-graphene multilayer composite material has a thickness in the range of 10 nanometers to 500 micrometers.

7. The composite wire harness according to claim 1, wherein: The copper-graphene multilayer composite material includes a plurality of alternating layers of graphene and copper.

8. The composite wire harness according to claim 1, wherein: The copper-graphene multilayer composite material includes graphene particles dispersed between a plurality of coated copper layers.

9. A stator including a composite wiring harness for a vehicle, comprising: a stator core including a plurality of channels defined by a plurality of teeth; as well as A composite wire harness is received in the plurality of channels, the composite wire harness comprising a plurality of copper wires, wherein each of the plurality of copper wires comprises a first surface; a copper-graphene multilayer composite material coated to the first surface of each of the plurality of copper wires, wherein the copper-graphene multilayer composite material comprises a second surface, and the copper at the second surface is oxidized; a fluoropolymer matrix formed around the oxidized copper surface; and a sheath encapsulating the plurality of fluoropolymer matrices.

10. A method of forming a composite wire harness for a stator, comprising: coating a fluorine-containing polymer on a first surface of the copper-graphene multilayer composite material formed on each of the plurality of copper wires; curing the fluoropolymer; consolidating the plurality of copper wires; forming a fluoropolymer matrix with the coated fluoropolymer, wherein the fluoropolymer matrix surrounds the first surface; as well as A sheath is formed around the fluoropolymer matrix.

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