Patent Application
20240204366
The present disclosure relates to traction battery assemblies for motor vehicles, and more specifically to traction battery assemblies having busbar modules.
Vehicles such as battery-electric vehicles and hybrid-electric vehicles contain a traction battery assembly to act as an energy source for the vehicle. The traction battery may include components and systems to assist in managing vehicle performance and operations. The traction battery may also include high-voltage components and may include an air or liquid thermal-management system to control the temperature of the battery.
According to one embodiment, a traction battery includes a stack of battery cells and a busbar. Each of the battery cells includes a terminal having a projecting portion extending from a body of the battery cell and a flat receding portion disposed at a first acute angle on a distal end of the projecting portion. The busbar includes a base and a plurality of flat connecting portions extending at a second acute angle from the base. A sum of the first acute angle and the second acute angle may be less than 90 degrees. The busbar may also include a plurality of stiffeners each extending between the base and a distal end of one of the connecting portions. Windows may be defined on the sides of the connecting portions and stiffeners. A thickness of the connecting portions may be less than one half of a thickness of the base and less than one half of a thickness of the stiffeners. Each flat receding portion is welded to a corresponding flat connecting portion. Each projecting portion may be deflected by a separating force between the corresponding receding portion and the corresponding connecting portion.
According to another embodiment, a traction battery includes a stack of battery cells and a busbar. Each of the battery cells includes a terminal having a projecting portion extending from a body of the battery cell and a flat receding portion disposed at an acute angle on a distal end of the projecting portion. The busbar has a central region and two side regions. Windows may be defined between the side regions and the central region. The central region defines a plurality of corrugations. Each corrugation includes a flat connecting portion and may include a stiffener. A thickness of the connecting portion may less than one half of a thickness of the stiffener and may be less than one half of a thickness of the side regions. Each flat receding portion is welded to a corresponding flat connecting portion. Each projecting portion may be deflected by a separating force between the corresponding receding portion and the corresponding connecting portion.
A method of assembling a traction battery includes bringing a busbar and a stack of battery cells together and then welding. The busbar includes a base and a plurality of flat connecting portions extending at a second acute angle from the base. Stiffeners may extend between the base and distal ends of the connecting portions. Each battery cell of the stack of battery cells includes a terminal having a projecting portion extending from a body of the battery cell and a flat receding portion disposed at a first acute angle on a distal end of the projecting portion. The busbar and battery cells are brought together such that separating forces between the flat connecting portions and the flat receding portion deflect the corresponding projecting portions. Each connecting portion is welded to a corresponding receding portion. The busbar may be formed by stamping a sheet metal blank to form the connecting portions and the stiffeners. Stamping the sheet metal blank may reduce a thickness of the connecting portions to less than one half of a thickness of the base.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
A traction battery or battery pack 24 stores energy that can be used by the electric machines 14. The traction battery 24 typically provides a high voltage direct current (DC) output from one or more battery cell arrays, sometimes referred to as battery cell stacks, within the traction battery 24. The battery cell arrays include one or more battery cells.
The battery cells, such as a prismatic, pouch, cylindrical, or any other type of cell, convert stored chemical energy to electrical energy. The cells may include a housing, a positive electrode (cathode), and a negative electrode (anode). An electrolyte allows ions to move between the anode and cathode during discharge, and then return during recharge. Terminals may allow current to flow out of the cell for use by the vehicle.
Different battery pack configurations may be available to address individual vehicle variables including packaging constraints and power requirements. The battery cells may be thermally managed with a thermal management system. Examples of thermal management systems include air cooling systems, liquid cooling systems, and a combination of air and liquid systems.
The traction battery 24 may be electrically connected to one or more power electronics modules 26 through one or more contactors (not shown). The one or more contactors isolate the traction battery 24 from other components when opened and connect the traction battery 24 to other components when closed. The power electronics module 26 may be electrically connected to the electric machines 14 and may provide the ability to bi-directionally transfer electrical energy between the traction battery 24 and the electric machines 14. For example, a typical traction battery 24 may provide a DC voltage while the electric machines 14 may require a three-phase alternating current (AC) voltage to function. The power electronics module 26 may convert the DC voltage to a three-phase AC voltage as required by the electric machines 14. In a regenerative mode, the power electronics module 26 may convert the three-phase AC voltage from the electric machines 14 acting as generators to the DC voltage required by the traction battery 24. The description herein is equally applicable to fully electric vehicles. In a fully electric vehicle, the hybrid transmission 16 may be a gear box connected to an electric machine 14 and the engine 18 is not present.
In addition to providing energy for propulsion, the traction battery 24 may provide energy for other vehicle electrical systems. A typical system may include a DC/DC converter module 28 that converts the high voltage DC output of the traction battery 24 to a low voltage DC supply that is compatible with other vehicle components. Other high-voltage loads, such as compressors and electric heaters, may be connected directly to the high-voltage supply without the use of a DC/DC converter module 28. In a typical vehicle, the low-voltage systems are electrically connected to an auxiliary battery 30, e.g., a 12-volt battery.
A battery energy control module (BECM) 33 may be in communication with the traction battery 24. The BECM 33 may act as a controller for the traction battery 24 and may also include an electronic monitoring system that manages temperature and charge state of each of the battery cells. The traction battery 24 may have a temperature sensor 31 such as a thermistor or other temperature gauge. The temperature sensor 31 may be in communication with the BECM 33 to provide temperature data regarding the traction battery 24.
The vehicle 12 may be recharged by a charging station connected to an external power source 36. The external power source 36 may be electrically connected to electric vehicle supply equipment (EVSE) 38. The external power source 36 may provide DC or AC electric power to the EVSE 38. The EVSE 38 may have a charge connector 40 for plugging into a charge port 34 of the vehicle 12. The charge port 34 may be any type of port configured to transfer power from the EVSE 38 to the vehicle 12. The charge port 34 may be electrically connected to a charger or on-board power conversion module 32. The power conversion module 32 may condition the power supplied from the EVSE 38 to provide the proper voltage and current levels to the traction battery 24. The power conversion module 32 may interface with the EVSE 38 to coordinate the delivery of power to the vehicle 12. The EVSE connector 40 may have pins that mate with corresponding recesses of the charge port 34.
The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus, e.g., Controller Area Network (CAN), or via dedicated electrical conduits.
During assembly of the battery cell stack, busbar 58 is moved into contact with several terminals as indicated by arrow 72 such that the parts have the relative positioning illustrated in
The busbar and terminal design as described above provides several advantages. The terminal does not protrude past the connecting portion and stiffener of the busbar. The window allows visual confirmation of correct orientation and positioning. The bends in the busbar prevent the connecting portion from warping, ensuring a flat weldable surface. Similarly, the bend in the terminal prevents the receding portion from warping, ensuring a flat surface for welding. The weldable area is relatively large. The gap between parts to be welded is reliably small or non-existent even in the presence of part-to-part variability. External clamping is not required during welding.
The busbar may be efficiently fabricated using a stamping process.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.
