Parallel Fuse Busbar Layout for Battery Thermal Runaway Containment
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Solution Overview
Problem
Current battery modules face challenges in preventing thermal runaway propagation due to short circuit currents, which can lead to increased resistance and voltage drop, reducing overall performance, and existing solutions that use current limiting elements at the cell level are not effective in mitigating this issue without compromising normal operating currents.
Innovation Solution
The implementation of current limiting elements in a parallel path within a cell group, integrated into busbars, and impedance balancing to ensure equal short circuit current distribution across all cells, preventing thermal runaway propagation while maintaining normal charge/discharge currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current limiting elements are added at the cell level to mitigate thermal runaway propagation, then thermal runaway protection is improved, but resistance and voltage drop increase reducing overall performance
Solution Approach 1:
The patent divides the current limiting function into two separate segments: (1) current limiting elements placed only in parallel paths between cell groups to block thermal runaway propagation, and (2) the series path left unrestricted for normal operating current. This segmentation allows thermal protection without compromising normal performance, as the series path does not contain resistive current limiting elements that would cause voltage drop during normal operation.
2Reliability
If current limiting elements are placed in series path to limit short circuit current, then thermal runaway propagation is prevented, but normal operating current is also limited reducing performance
Solution Approach 1:
The patent introduces an intermediary structure - a parallel path with current limiting elements - that acts as a mediator between the series-connected cell groups. This parallel path with fuse allows short circuit current to be diverted and limited without affecting the series path that carries normal operating current, thus preventing thermal runaway while maintaining full charge/discharge capacity.
3Reliability
If parallel fusing scheme is implemented without impedance balancing, then thermal runaway mitigation is achieved, but current distribution becomes uneven reducing reliability
Solution Approach 1:
The patent applies impedance balancing to create equipotential conditions across all parallel paths. By ensuring equal impedance in each parallel path containing current limiting elements, the system achieves uniform current distribution during short circuit events. This prevents any single path from bearing excessive current that could compromise the reliability of the thermal runaway mitigation scheme.
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 solution effectively mitigates thermal runaway propagation by ensuring equal short circuit current distribution across all cells, enhancing reliability and preventing thermal runaway without affecting normal operating currents, thus improving the performance and safety of battery modules.
Implementation Method 1
The cells in parallel with the shorted cell discharge through the short, producing ohmic heating and sometimes arcing. This heating can sustain flames and inject enough heat into the affected cells to result in propagation.
Implementation Method 2
to provide impedance balancing and continuity assurance for the parallel connected fuses
Data Source
AI summary
A battery system, battery packs and battery modules are disclosed. The battery module comprises a plurality of cells mounted within a housing. The module has a plurality of groups of cells. Each group comprises a plurality of parallel connected cells from among the plurality of cells. The plurality of groups is connected in series. The module has a plurality of current limiting elements. Each current limiting element are electrically connected in a parallel path to one or both terminals of cells which are parallelly connected. The current limiting elements may be integrated in or separate from busbars which are connected to terminals of the cells. Impedance balancing is provided to the parallel fusing scheme to improve the overall reliability of the battery module. The battery module configuration allows for continuity assurance testing of the parallel connections to ensure detection of blown fuses or broken connections in the module.