Bus Bar Weld Repair for Reliable Traction Battery Connections
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Solution Overview
Problem
Conventional traction battery packs face challenges in reliably connecting bus bars to battery cell terminals due to the need for precise welding and the potential for defects, which can affect the electrical connectivity and overall performance of the battery system.
Innovation Solution
A method involving primary and secondary laser welding operations, where a primary weld bead is formed adjacent to a weld repair zone, and a repair weld bead is created if the primary weld fails a post-electrical test, ensuring reliable electrical connection and geometric accuracy in bus bar welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary welding operation is performed on a bus bar to join it to a battery cell terminal, then electrical connection is established, but weld defects may occur affecting connection reliability
Solution Approach 1:
The weld repair zone is prepared in advance by cleaning the bus bar surface and positioning the pressing device to cover the repair zone during the primary welding operation. This preliminary preparation enables quick and effective repair if weld defects occur, thereby improving weld connection reliability without adding significant complexity to the primary welding process
Solution Approach 2:
A pressing device is introduced as an intermediary tool that applies controlled pressure to the bus bar at the weld repair zone during both primary and secondary welding operations. This pressing device enables precise control of the welding process and facilitates defect repair by maintaining proper contact between the bus bar and terminal throughout the welding and repair operations
2Reliability
If a secondary welding operation is performed to repair weld defects, then connection reliability is improved, but manufacturing time and process complexity increase
Solution Approach 1:
The pressing device is positioned to cover the weld repair zone before the primary welding operation begins. This preliminary positioning allows the device to immediately transition to repairing weld defects without requiring repositioning or setup time, thereby minimizing the time loss associated with secondary welding operations while maintaining connection reliability
Solution Approach 2:
The process includes electrical testing of the primary weld bead to detect defects, providing feedback that triggers the secondary welding operation only when needed. This feedback mechanism avoids unnecessary repair operations and their associated time losses, while ensuring that defects are repaired when they occur, thus optimizing the balance between reliability improvement and time efficiency
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 approach ensures reliable electrical connections between bus bars and battery cell terminals, allowing for effective repair of weld defects and maintaining geometric accuracy, thereby enhancing the performance and reliability of the traction battery pack.
Implementation Method 1
performing a primary welding operation on a bus bar of a battery system of the traction battery pack; performing a secondary welding operation on the bus bar. During the secondary welding operation, a repair weld bead is formed within a weld repair zone of the bus bar
Data Source
AI summary
Bus bar welding solutions are disclosed for electrically connecting bus bars to battery cell terminals within a battery system. An exemplary method may include performing weld repair operations. The weld repair operations may include creating a repair weld bead at a weld repair zone of the bus bar. The weld repair zone may include an area of the bus bar that is covered by a pressing device during a pressing operation and a primary welding operation of the method.