Multi-Level Busbar Structure for Overlapping Battery Cell Tabs
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Solution Overview
Problem
Traditional single-level busbar configurations in battery modules restrict the length of cell tabs, leading to overlapping issues and reduced positional tolerances, necessitating trimming and increasing scrap rates.
Innovation Solution
The implementation of multi-level busbars with distinct tiers or levels, featuring an elongated step transition or ramped surfaces, allows longer cell tabs to overlap without interference, ensuring flat contact for high-integrity welds and reducing the need for trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-level busbar configuration is used, then the structure is simple, but the cell tabs must be trimmed to fit limited space, increasing scrap rates
Solution Approach 1:
The busbar transitions from a single-level flat surface to a multi-level structure with vertical height variations. The step transition creates distinct elevation levels that allow cell tabs of different lengths to be positioned without overlapping, eliminating the need for trimming and reducing material waste.
Solution Approach 2:
The busbar surface is segmented into multiple levels or tiers, with each level providing a distinct positioning zone for cell tabs. This segmentation allows longer and shorter cell tabs to occupy different vertical zones, preventing interference and eliminating the need for uniform length requirements.
2Reliability
If cell tabs are made longer to improve weld surface area, then welding integrity improves, but tabs overlap and interfere with each other on single-level busbars
Solution Approach 1:
By introducing vertical height differences through step transitions, the busbar creates separate spatial zones for different cell tabs. This allows tabs to maintain their full length for adequate welding surface area while preventing overlap by positioning them at different elevations.
3Area of stationary object
If cell tabs are trimmed shorter to fit single-level busbars, then assembly space is reduced, but weld surface area is insufficient for high-quality connections
Solution Approach 1:
The multi-level busbar utilizes vertical space to accommodate full-length cell tabs, eliminating the need to trim tabs shorter. Each level provides adequate weld surface area while the vertical separation prevents space conflicts, maintaining both compact assembly and high-quality welding.
4Adaptability or versatility
If a multi-level busbar with step transition is implemented, then cell tabs can overlap without interference, but the busbar construction becomes more complex
Solution Approach 1:
The busbar incorporates vertical height variations through step transitions, creating multiple elevation levels. This dimensional change enables the busbar to accommodate cell tabs of varying lengths without interference, as tabs can be positioned at different heights rather than requiring uniform length or complex lateral arrangements.
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
Enables longer cell tabs with improved assembly tolerances, reduces scrap rates, and enhances structural integrity of tab-to-busbar welds, thereby improving manufacturing efficiency and durability.
Implementation Method 1
The folded cell tabs are then conductively joined to the busbars, typically using a laser welding process
Implementation Method 2
The elongated step transition separates the first and second levels, and has a height dimension configured to allow the first and second tab groups to overlap one another prior to welding
Data Source
AI summary
A multi-level busbar for interconnecting flexible cell tabs within a battery module of a battery electric system, e.g., of a motor vehicle having a traction motor and road wheels, includes first and second busbar surfaces and an elongated step transition. The first busbar surface is arranged at a first level of the busbar and is configured to be welded to a first tab group of the cell tabs. The second busbar surface is arranged at a second level of the busbar, and configured to be welded to a second tab group of the cell tabs. The step transition has a height dimension configured to allow the first and second tab groups to overlap when folded against and welded to the busbar.