Battery Pack Bus Bar with Variable Cross Section
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Solution Overview
Problem
Battery packs in electric vehicles face increased heat loss in bus bars during charge/discharge cycles, which can lead to reduced efficiency and increased weight if addressed by simply enlarging the bus bars, potentially shortening EV travel distance or deteriorating fuel consumption.
Innovation Solution
The bus bar configuration is optimized by increasing the cross-sectional area only in regions where higher currents flow, while maintaining smaller areas in regions with lower currents, thereby reducing heat loss without excessive weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the size of the bus bars is increased to suppress heat loss, then heat loss is reduced, but the weight of the battery pack increases
Solution Approach 1:
The bus bar is designed with a non-uniform cross-sectional area where the intermediate region (connecting cells with higher current) has a larger cross-sectional area than the first and second regions (connecting cells with lower current). This local variation in geometry concentrates the material where the current density is highest, thereby reducing heat loss in the most critical areas without increasing the overall weight of the bus bar structure.
2Power
If cells are connected in parallel to increase charge/discharge current, then charge/discharge capacity is improved, but heat loss in bus bars increases
Solution Approach 1:
The bus bar structure is optimized with varying cross-sectional areas along its length, with the intermediate region having a larger area where higher currents from parallel-connected cells converge. This design allows the bus bar to handle increased charge/discharge currents from parallel cell configurations while minimizing heat loss through strategic material distribution in high-current zones.
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
This configuration effectively reduces heat loss in high-current regions while minimizing weight gain in other areas, enhancing battery pack reliability and efficiency.
Implementation Method 1
During the charge/discharge of the battery pack, heat loss (Joule heat) is generated in the bus bars
Data Source
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AI summary
A battery pack (10) includes a bus bar (32), a first module, and a second module. The bus bar (32) extends in a predetermined direction and includes a first region, a second region and an intermediate region. The first module includes a plurality of cells (101, 102, 103) each including a negative electrode terminal connected to the first region. The second module includes a plurality of cells (104, 105, 106) each including a positive electrode terminal connected to the second region. The negative electrode terminals are arranged in the predetermined direction in the first region. The positive electrode terminals are arranged in the predetermined direction in the second region. In a cross section perpendicular to the predetermined direction, a cross-sectional area of the intermediate region is greater than a cross-sectional area of at least a part of the first region and is greater than a cross-sectional area of at least a part of the second region.