Patent Application
20250196790
Electric and hybrid electric vehicle technology has been enabled by the development and deployment of rechargeable, secondary batteries which provide energy to electric traction motors, servo motors, and other electronics in the vehicle. Numerous electrical connections and electrical components are provided to transfer energy between the battery, motor, and electrical components in the vehicle. For example, traction motors include a stationary stator and a rotor rotatably positioned within the stator. The stator may include windings of coiled wire wrapped around teeth in the stator. When the stator is energized with an alternating electrical current (AC), the windings create magnetic fields and permanent magnets in the rotor try to align with the magnetic fields causing the rotor to rotate within the stator. The windings are coupled to bus bars and the bus bars are then coupled to additional components in the power distribution system.
However, in alternating electric current (AC) power distribution, current density tends to be larger near the surface of conductors, such as the windings and busbars of the stator, and decreases approaching the core of the conductors. This effectively decreases the cross-section of the larger conductors and increases effective resistance. This effect, known as the skin effect, increases as the frequency of the alternating current increases. To combat this effect, several smaller conductors may be used to replace a large conductor. Each of the smaller conductors have a smaller cross-sectional area than the large conductor, but together may exhibit a cross-sectional area similar to the large conductor. In addition, coatings and other composite materials have been and are being developed to address and leverage the skin effect.
While present conductors in vehicles achieve their intended purpose, there is a need for new and improved conductors and methods of joining the conductors to other conductors and electrical components in the propulsion system as well as for other applications.
According to several aspects, the present disclosure relates to an electrical connection for a vehicle. The electrical connection includes a first electrical component including a first joining area. The electrical connection also includes a conductor including a second joining area. The conductor is joined at the second joining area to the first joining area of the first electrical component. In addition, the electrical connection includes a fusion zone formed in the first electrical component in the first joining area. The conductor includes a substrate including a first surface, and a copper-graphene multilayer composite formed on the first surface. The copper-graphene multilayer composite includes at least one of the following composite structures: a) alternating layers of graphene and copper deposited on the substrate, b) graphene particles dispersed in a copper matrix, and c) alternating layers of graphene and copper deposited on a copper foil, wherein the copper foil is wrapped around the substrate.
In embodiments of the above, the substrate comprises at least one material selected from the group consisting of copper, steel, and aluminum.
In any of the above embodiments, the electrical connection further includes a fusion zone formed in the first electrical component in the first joining area.
In any of the above embodiments, further including graphene present in the fusion zone of the first electrical component. In further embodiments, a layer of nickel is present between the first joining area and the second joining area and nickel is present in the fusion zone of the first electrical component. Alternatively, the copper-graphene multilayer composite is not present on the first surface at the second joining area.
In any of the above embodiments, an electrically conductive adhesive contacts the first joining area of the first electrical component and the second joining area of the conductor. In further embodiments, the conductive adhesive is at least one of an electrically conductive glue and an electrically conductive adhesive tape.
In any of the above embodiments, the first electrical component is a winding in a stator and the conductor is a busbar. Alternatively, in any of the above embodiments, the first electrical component is a battery and the battery includes the first joining area formed of at least one of a tab and a terminal.
According to additional aspects, the present disclosure is directed to a method of forming an electrical connection for a vehicle. The method includes joining a first electrical component including a first joining area to a conductor including a second joining area. The conductor includes a substrate including a first surface and a copper-graphene multilayer composite formed on the first surface. The method further includes forming a fusion zone between the first electrical component in the first joining area and the conductor in the second joining area. The copper-graphene multilayer composite includes at least one of the following composite structures: a) alternating layers of graphene and copper deposited on the substrate, b) graphene particles dispersed in a copper matrix, and c) alternating layers of graphene and copper deposited on a copper foil, wherein the copper foil is wrapped around the substrate.
In embodiments of the above, joining comprises laser welding. Alternatively, joining is performed by at least one of the following welding processes: ultrasonic welding and friction welding.
In any embodiments of the above, graphene is present in the first electrical component in the fusion zone. In further embodiments, the method further includes supplying nickel in the form of foil between the first joining area and the second joining area prior to joining and nickel is present in the first electrical component in the fusion zone. In alternative or additional embodiments, the method further includes supplying nickel in the form of a wire, which is fed between the first joining area and the second joining area. Nickel is present in the first electrical component in the fusion zone. Alternatively, the method further includes removing a portion of the copper-graphene multilayer composite from the first surface at the second joining area before joining the first electrical component to the conductor, wherein the laser power during removing is less than the laser power during joining.
In any of the above embodiments, the first electrical component includes a secondary battery, wherein the secondary battery is a pouch battery including a tab and the first joining area is located on the tab. Alternatively or additionally, in any of the above embodiments, the first electrical component includes a secondary battery, wherein the secondary battery is a cylindrical battery including a terminal and the first joining area is located at the terminal.
In any of the above embodiments, the method includes joining the first electrical component including a steel terminal and the first joining area on the steel terminal to the second joining area of the conductor. The first electrical component is a secondary a battery, and the conductor is formed of copper. The method further includes forming the first fusion zone in the first electrical component in the first joining area, joining a second electrical component including a fourth joining area to a third joining area of the conductor, and forming a second fusion zone in the second electrical component in the fourth joining area. Alternatively, in any of the above embodiments, the method includes joining the first electrical component to a conductor formed of copper. The first electrical component being a winding, the winding providing the first joining area, and the conductor being a busbar, the busbar providing the second joining area.
According to yet additional aspects, the present disclosure relates to a method of joining an electrical component for a vehicle. The method includes applying a layer of adhesive to a first joining area of a first electrical component and applying the layer of adhesive to a second joining area of a conductor, wherein the conductor includes a substrate including a first surface and a copper-graphene multilayer composite on the first surface. The method also includes joining the first electrical component to the conductor, wherein the layer of adhesive comprises at least one of an electrically conductive glue and an electrically conductive adhesive tape. The copper-graphene multilayer composite includes at least one of the following composite structures: a) alternating layers of graphene and copper deposited on the substrate, b) graphene particles dispersed in a copper matrix, and c) alternating layers of graphene and copper deposited on a copper foil, wherein the copper foil is wrapped around the substrate.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding introduction, summary, or the following detailed description. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
Reference will now be made in detail to several examples of the disclosure that are illustrated in accompanying drawings. Whenever possible, the same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale.
The present disclosure relates to electrical connections and methods of forming electrical connections and electric circuits in energy storage and propulsion systems of a vehicle, including in the battery module and the electric motor.
As used herein, the term “vehicle” is not limited to automobiles. While the present technology is described primarily herein in connection with electric vehicles, the technology is not limited to electric vehicles, but hybrid electric vehicles and internal combustion engines as well. In addition, the concepts can be used in a wide variety of applications, such as in connection with components used in motorcycles, mopeds, locomotives, aircraft, marine craft, and other vehicles, as well as in other applications utilizing electrical connections, such as in portable power stations, such as those used for powering remote job sites and emergency back-up power supplies, and permanent power stations associated with buildings and equipment, all of which may be powered by, for example, solar or wind-powered generator systems, power mains, and fuel based power generators such as gasoline or diesel generators as well as sterling engines.
As alluded to above, the energy storage and propulsion system 120 generally includes an electric motor 124 and a secondary battery 126 for powering the electric motor 124. Further, in many embodiments, the propulsion system 120 includes an inverter 128 for changing power from DC (direct current) as provided by the battery 126 to AC (alternating current) as it is used by the electric motor 124. The inverter 128 may be included in a power electronics module 130, which includes e.g., transistors and diodes, for switching the power from DC to AC and vice-versa. In embodiments, the battery 126 is connected to the electric motor 124 through the power electronics module 130.
A controller 132, which may also be included in the power electronics module 130 or otherwise connected to the power electronics module 130, is connected to the inverter 128 and is programmed to control and manage the operations of the electric motor 124 and associated hardware, including the inverter 128. The electric motor 124 is connected to a transmission (drive unit) 136, and drive line 138, which transfers mechanical power and rotation to the wheels 140 of the vehicle 100. The controller 132 includes one or more one or more processors and tangible, non-transitory memory 134.
With reference again to the electric motor 124, the electric motor 124, powered by the battery 126, includes a stator 142 and a rotor 144 arranged in a rotatable manner within the stator 142. The stator 142 is the stationary part of the electric motor 124. When energized with an alternating current (AC), the stator 142 provides a rotating magnetic field with which the stationary magnetic field of the rotor 144 tries to align with, causing the rotor 144 to rotate, in what may be referred to as “motoring” mode. In traction electric vehicle applications, the motoring mode provides propulsion to the vehicle 100. In other applications, the rotor's 144 rotating field (as caused by physical rotation) generates an electric current in the stator 142—this mode of operation is referred to as “generation” and the electric motor 124 used in this way is used as a generator. Generation mode takes some of the energy recovered from braking, e.g., when the vehicle is in the process of slowing and stopping and stores it back in the battery 126.
Reference is made to
In embodiments, the conductors 122, 148, 164 (generally referred to as conductor 180) are formed from composites, an embodiment of which is illustrated in
The substrate includes a surface 184, including a copper-graphene multilayer composite 186 formed on the surface 184. In embodiments, the copper-graphene multilayer composite 186 exhibits 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 the percentage of conductivity a material has relative to copper, which is considered 100 percent conductive and references a copper having a resistivity of 1.7241 microohm-centimeters at 20 degrees Celsius. The copper-graphene multilayer composite exhibits a number of composite structures. In embodiments, the copper-graphene multilayer composite 186 includes one or more alternating layers of copper and graphene deposited on the substrate 182. In such embodiments, graphene is first deposited on each substrate 182 and then copper is deposited over the graphene, and the process is repeated until the desired number of layers are present. In additional or alternative embodiments, graphene particles are dispersed between a plurality of coated copper layers. In yet further embodiments of the above, the copper and graphene may be deposited, either as alternating layers of the copper and graphene or with graphene particles in a copper matrix, onto a copper foil that may then be wrapped around the substrate 182. The copper-graphene multilayer composite of any of the above embodiments, may be applied directly to a substrate 182 or to a copper foil, which is wrapped on a substrate 182, 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 composites 186 may exhibit a thickness in the range of 5 nanometers to 500 micrometers, including all values and ranges therein such as in the range of 30 micrometers to 300 micrometers. When foil is present, the foil exhibits a thickness in the range of 5 micrometers to 25 micrometers, including all values and ranges therein, in addition to the remaining copper-graphene multilayer composite.
The conductors 180 are joined to one or more electrical components, such as to other conductors as illustrated in
For example, reference is made to
In embodiments, the conductors 180 and the electrical components 190 are joined by a welding process, such as a laser welding process, a friction welding process, or an ultrasonic welding process. Laser welding processes include processes that utilize a laser beam to melt and join the joining areas together. Friction welding processes utilize the generation of friction to melt and join the joining areas together and include processes such as friction stir welding, rotary friction welding, and linear friction welding. Ultrasonic welding utilizes a process that utilizes local, high frequency ultrasonic vibrations.
However, in embodiments, graphene may be deleterious to the joint formed between the conductor 180 and electrical component 190. Thus, without being bound to any particular theory, the wettability of the graphene may be adjusted through the addition of nickel to the weld joint. As illustrated in
Alternatively, or additionally, to the embodiment illustrated in
While the above processes are illustrated as being performed with a laser, it may be appreciated that joining the conductor 180 to the electrical component 190 may be performed using other processes described above. Further, ablation of the copper-graphene multilayer composite may be performed using an alternative process such as an etching process or a sanding process.
The connections between conductors including copper-graphene multilayer composite coatings and target conductors provides a number of advantages. Such advantages include enabling the provision of conductors including composite coatings for leveraging the skin effect. Another advantage, of welding, is the provision of a method to join the copper-graphene multilayer coating with a target, such as a battery steel can. While the ordered structure of the graphene layer may be interrupted in the fusion zone, the composite is still relatively high in conductivity. Further, the use of nickel provides an additional advantage of increasing the wettability of the graphene in the fusion zone. If maintenance of the ordered structure of the graphene in the copper-graphene multilayer composite, then an additive method of joining the coated conductor and target may be used. Further, defocus beam burning and welding may also advantageously reduce graphene imperfections.
As used herein, the term “controller” and related terms such as microcontroller, control module, module, control, control unit, processor and similar terms refer to one or various combinations of Application Specific Integrated Circuit(s) (ASIC), Field-Programmable Gate Array (FPGA), electronic circuit(s), central processing unit(s), e.g., microprocessor(s) and associated non-transitory memory component (s) in the form of memory and storage devices (read only, programmable read only, random access, hard drive, etc.). The controller 132 may also consist of multiple controllers which are in electrical communication with each other. The controller 132 may be inter-connected with additional systems and/or controllers of the vehicle 100, allowing the controller 132 to access data such as, for example, speed, acceleration, braking, and steering angle of the vehicle 100.
A processor may be a custom made 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 chip set), a macro processor, a combination thereof, or generally a device for executing instructions.
The tangible, non-transitory memory 134 may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM is a persistent or non-volatile memory that may be used to store various operating variables while the processor is powered down. The tangible, non-transitory memory 134 may be implemented using a number of memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or another electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller 132 to control various systems of the vehicle 100.
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 are not to be regarded as a departure from the spirit and scope of the present disclosure.
