Battery Pack Fault Isolation via Balancing Lines
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Solution Overview
Problem
Large capacity battery systems for electric vehicles face safety concerns due to thermal runaway triggered by internal shorts and other failures, as existing safety technologies developed for small capacity batteries are ineffective at the larger scale, and there is a lack of reliable systems for detecting faults and isolating them electrically.
Innovation Solution
A battery pack design with parallel branches, balancing lines, and current meters that detect internal short circuits by measuring current differences and trigger switches or fuses to isolate faulty cells, preventing further energy feed and reducing the risk of thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small capacity battery safety technologies (FTC, CID, shutdown separator) are applied to large capacity battery systems, then safety incident prevention is improved, but the safety technologies become ineffective due to scaling effects
Solution Approach 1:
The patent segments the battery system into multiple parallel branches, each with its own safety monitoring and isolation capability. This allows safety functions to be distributed across the system rather than relying on a single centralized safety mechanism, making the system adaptable to large capacity configurations while maintaining effectiveness of safety interventions.
Solution Approach 2:
The patent changes the operational parameters of safety devices by introducing adjustable current thresholds and timing delays that can be optimized for large capacity batteries. The safety technologies are adapted to account for the different electrical and thermal characteristics of large capacity systems, allowing them to remain effective despite scaling effects.
2Reliability
If multiple redundant safety layers are implemented in large capacity battery systems, then safety coverage is improved, but system complexity and cost increase dramatically
Solution Approach 1:
The patent merges multiple safety functions into a unified monitoring system that tracks current distribution across parallel branches. By combining fault detection, fault localization, and isolation functions into a single integrated system with shared sensors and control logic, the patent achieves comprehensive safety coverage while avoiding the complexity multiplication that would result from implementing separate redundant safety layers.
3Reliability
If comprehensive pack level safety assessment is performed, then safety performance is improved, but assessment cost and time increase significantly
Solution Approach 1:
The patent incorporates safety monitoring functions directly into the operational battery management system, allowing continuous safety assessment during normal operation rather than requiring separate pre-deployment testing. The system performs preliminary safety evaluations by monitoring current distribution patterns and detecting anomalies in real-time, enabling comprehensive safety performance verification without additional time loss.
4Object-affected harmful factors
If fault detection and electrical isolation systems are added to large capacity battery systems, then thermal runaway risk is reduced, but device complexity increases
Solution Approach 1:
The patent introduces balancing lines as intermediary elements that serve dual purposes: they enable passive current redistribution to maintain cell voltage balance during normal operation, and they provide a controlled pathway for current redistribution during fault conditions. This intermediary structure allows the system to achieve fault detection and isolation capabilities while utilizing existing system components, thereby limiting the increase in device complexity.
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
The solution effectively locates and isolates faulty cells in large capacity battery systems, enhancing safety by preventing further electrical energy from feeding into faults and reducing the risk of thermal runaway, thus ensuring safer operation of electric vehicles.
Implementation Method 1
each having a resistance that is calibrated to force the balancing current onto the power lines when the balancing current increases due to an internal short circuit
Implementation Method 2
each having a resistance that is calibrated to force the balancing current onto the power lines when the balancing current increases due to an internal short circuit
Data Source
AI summary
Fail-safe systems and design methodologies for large capacity battery systems are disclosed. The disclosed systems and methodologies serve to locate a faulty cell in a large capacity battery, such as a cell having an internal short circuit, determine whether the fault is evolving, and electrically isolate the faulty cell from the rest of the battery, preventing further electrical energy from feeding into the fault.