Battery Module Gradient Resistance Bus Bar Current Distribution
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Solution Overview
Problem
In battery modules for electric vehicles, current deviation between cells connected in parallel leads to uneven charging and discharging, reducing the maximum allowable current and causing temperature and lifespan deviations among cells.
Innovation Solution
The battery module employs first and second connection members with resistances that increase gradually along the array, configured by a series of resistors and bus bars, where the resistances of these members are determined to satisfy the equation RBk = ((n-k)/k) * RTk, ensuring uniform current distribution across cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery cells are connected in parallel to increase capacity, then the battery capacity increases, but current deviation between cells occurs leading to uneven charging and discharging
Solution Approach 1:
The connection members are designed with non-uniform resistance distribution, where the resistance per unit length varies along the length of the connection member. Specifically, the resistance is configured to be higher near the common node and lower at the outer battery cell connections, creating local resistance differences that compensate for current deviation between parallel-connected battery cells.
Solution Approach 2:
The resistance parameter of the connection members is deliberately changed along their length. The resistance per unit length is configured to increase or decrease in a specific pattern from one end to the other, transforming the uniform resistance design into a gradient resistance design to achieve uniform current distribution across parallel battery cells.
2Ease of manufacture
If connection members have uniform resistance, then manufacturing is simple, but current deviation causes temperature and lifespan deviations among cells
Solution Approach 1:
The connection members incorporate local resistance variations where specific segments have different resistance values. This is achieved by configuring the resistance per unit length to vary along the length, creating localized high-resistance regions near the common node that help equalize current distribution and reduce temperature deviations among battery cells.
3Reliability
If connection members have higher resistance near common node, then current distribution uniformity improves, but manufacturing precision requirements increase
Solution Approach 1:
The resistance parameter is systematically varied along the connection member length according to a predetermined gradient pattern. This controlled parameter change creates the necessary resistance distribution to achieve uniform current sharing, with the resistance per unit length changing in a predictable manner that can be manufactured with standard precision tolerances.
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 minimizes current deviation between cells, allowing for uniform charging and discharging, increasing the maximum allowable current and reducing temperature and lifespan deviations, thereby enhancing the battery module's performance and longevity.
Implementation Method 1
the first connection member is configured such that as the distance from the first common node is increased, a resistance for unit length is gradually increased and the second connection member is configured such that as the distance from the second common node is increased, a resistance for unit length is gradually increased
Data Source
AI summary
A battery module includes battery cells, a first connection member connecting first terminals of the battery cells to each other and connected to a first common node, and a second connection member connecting second terminals of the battery cells to each other and connected to a second common node. The first common node is adjacent to a first battery cell between first and second battery cells at the outermost periphery of the battery cells. The second common node is adjacent to the second battery cell between the first and second battery cells. The first connection member is configured such that as the distance from the first common node is increased, a resistance for unit length is gradually increased. The second connection member is configured such that as the distance from the second common node is increased, a resistance for unit length is gradually increased.