Off-Axis Compliant Busbar for EV Battery Packs
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Solution Overview
Problem
Traditional busbars in electric vehicle battery packs lack flexibility, leading to potential failure due to dislocation of cells from heating, cooling, and vibrations, and require increased thickness for higher current capabilities, which compromises volumetric efficiency and increases the risk of short circuits.
Innovation Solution
A low-profile busbar with a spring-like middle portion featuring bends and slits, allowing off-axis and off-plane compliance, enabling flexibility while maintaining structural integrity and high current carrying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rigid busbar design is used, then manufacturing simplicity is maintained, but flexibility and compliance are lost leading to potential failure from cell dislocation
Solution Approach 1:
The busbar is divided into three distinct sections: rigid end portions for stable electrical connection and a flexible middle portion with bends and slits for compliance. This segmentation allows different parts of the busbar to have different mechanical properties, resolving the contradiction between rigidity for manufacturing simplicity and flexibility for reliability.
Solution Approach 2:
The middle portion of the busbar is given special local quality through the addition of bends and slits, making it flexible and compliant, while the end portions remain rigid for stable connections. This localized modification resolves the contradiction by applying flexibility only where needed without compromising the overall structural integrity.
2Power
If busbar thickness is increased for higher current capability, then current carrying capacity is improved, but volumetric efficiency deteriorates and short circuit risk increases
Solution Approach 1:
The busbar uses a thin-walled tube structure with strategic bends and slits that provides both flexibility and adequate current carrying capacity. This flexible shell structure eliminates the need for thick rigid busbars, resolving the contradiction between power capability and volumetric efficiency.
Solution Approach 2:
The busbar incorporates curved bends in the middle portion that provide mechanical compliance while maintaining electrical conductivity. The curved geometry allows the busbar to accommodate cell movement without requiring increased thickness, thus maintaining both power capability and volumetric efficiency.
3Adaptability or versatility
If rigid busbar structure is used, then structural integrity is maintained, but adaptability to cell movement from thermal and vibrational effects is lost
Solution Approach 1:
The busbar transitions from a static rigid structure to a dynamic structure with a flexible middle portion that can adapt its shape in response to thermal expansion, contraction, and vibrational forces. This dynamic capability allows the busbar to maintain structural integrity while accommodating cell movement.
Solution Approach 2:
The bends and slits in the middle portion are pre-configured to provide compliance and absorb mechanical stress from thermal and vibrational effects before they can cause damage. This beforehand cushioning allows the busbar to maintain strength while adapting to cell dislocation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flexible busbar design enhances volumetric efficiency, reduces the risk of short circuits, and accommodates higher current and voltage levels, ensuring durability and safety in battery pack assemblies.
Implementation Method 1
The at least one bend and the at least one slit may provide the spring-like middle portion with a spring-like characteristic that allows off-axis compliance of a center of the first terminal contact area relative to a center of the second terminal contact area
Data Source
AI summary
A busbar that includes a body having a first end corresponding to a first terminal contact area of the busbar, a second end opposite the first end, corresponding to a second terminal contact area of the busbar, and a spring-like middle portion located between the first end.