Layered Aluminum Busbar Structure for High-Current Flexibility
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Solution Overview
Problem
Conventional busbars in electric vehicle battery packs face challenges in achieving high continuous current carrying capacity while maintaining flexibility and compactness, leading to reduced volumetric energy density and increased material stiffness, which can result in safety and longevity issues due to excessive thickness and offset heights.
Innovation Solution
A low-profile busbar design using stacked aluminum layers with specific thickness, offset radius of curvature, and offset height, laser-welded to provide defined flexibility and high current carrying capacity, minimizing vertical profile and maintaining volumetric energy density, and employing a method of laser welding with precise parameters to secure the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional busbars use increased thickness to achieve high current carrying capacity, then current capacity improves, but material stiffness increases and flexibility deteriorates
Solution Approach 1:
The busbar is divided into multiple thin aluminum layers (first aluminum layer, second aluminum layer, third aluminum layer) stacked together. Each layer has a thickness of 0.5mm to 2mm, which maintains flexibility while the stacked configuration achieves the required current carrying capacity of 100A to 500A. This segmentation allows the busbar to bend without excessive stiffness.
Solution Approach 2:
The invention uses a composite structure of multiple aluminum layers bonded together through laser welding. The composite configuration of thin layers provides both the electrical conductivity needed for high current capacity and the flexibility required for battery pack assembly, resolving the contradiction between stiffness and flexibility.
2Ease of operation
If conventional busbars use increased offset height to provide flexibility, then flexibility improves, but vertical profile increases and volumetric energy density decreases
Solution Approach 1:
Instead of using a single thick busbar with large offset height, the invention segments the structure into multiple thin layers. The offsets are formed within this layered structure, achieving the necessary flexibility through the layered configuration itself rather than requiring large vertical offsets, thus maintaining a compact vertical profile.
Solution Approach 2:
The flexibility is achieved by utilizing the layered structure in the vertical dimension, where multiple thin layers can bend relative to each other. This allows the busbar to accommodate battery cell expansions and contractions without requiring large horizontal offsets, thereby maintaining a compact vertical profile and high volumetric energy density.
3Ease of operation
If conventional busbars use stacked aluminum layers, then flexibility improves, but manufacturing complexity increases due to welding requirements
Solution Approach 1:
The invention replaces traditional mechanical joining methods (such as riveting, bolting, or adhesive bonding) with laser welding technology. Laser welding provides precise, automated, and strong bonding between aluminum layers, reducing manufacturing complexity despite the multi-layer structure. The laser welding process can be precisely controlled to join the thin aluminum layers efficiently.
4Power
If conventional busbars increase thickness to reduce resistance, then electrical conductivity improves, but heat generation increases due to higher material stiffness
Solution Approach 1:
The segmented multi-layer structure provides sufficient cross-sectional area for low electrical resistance while allowing better heat dissipation through the layered configuration. The thin layers can expand and contract independently, reducing thermal stress and heat generation compared to a solid thick busbar, while maintaining the required current carrying capacity of 100A to 500A.
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 solution enables a busbar with high continuous current carrying capacity between 100 A to 500 A, maintaining flexibility and compactness, reducing material stiffness, and ensuring safety and longevity by minimizing temperature rise and resistance, thus optimizing volumetric efficiency and energy density.
Implementation Method 1
secured to the first aluminum layer with one or more laser welds at the first and second ends
Data Source
AI summary
A busbar that includes a low profile, flexible body made of aluminum layers stacked together on their longitudinal surfaces. The aluminum layers are laser welded together and are designed to have an offset at a middle portion such that the middle portion has a raised profile. A method of laser welding the aluminum layers is also disclosed.