Battery Management System for Early Internal Short-Circuit Detection
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Solution Overview
Problem
Current methods for detecting internal short-circuits in lithium-ion batteries are inadequate for early detection, as they rely on temperature-dependent internal resistance measurements and cannot quantify the short-circuit build-up process, making it difficult to prevent catastrophic events like thermal runaway.
Innovation Solution
A battery management system (BMS) that monitors terminal current, state of charge, and battery effective capacity to detect internal short-circuits by tracking charge flow and losses during active and standby states, using a machine-readable medium and processing units to produce alarm signals when predetermined criteria are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If internal resistance detection is used to detect internal short-circuits, then the detection capability is improved, but the measurement precision deteriorates due to temperature and current dependencies
Solution Approach 1:
The patent introduces charge loss as an intermediary parameter to detect internal short-circuits. Instead of directly measuring internal resistance (which is affected by temperature and current), the system measures charge flow into and out of the battery and calculates charge loss. This intermediary approach allows detection of internal short-circuits without the measurement precision issues of direct resistance measurement.
Solution Approach 2:
The patent replaces the electrical measurement approach (measuring voltage and current to calculate resistance) with a charge-based approach. By integrating current over time to calculate charge flow and comparing charge in versus charge out, the system substitutes the resistance measurement mechanism with a charge balance mechanism that is not affected by temperature or current level dependencies.
2Reliability
If temperature detection is used to prevent thermal runaway, then the safety monitoring is improved, but the early detection capability deteriorates because temperature rise occurs after short-circuit build-up
Solution Approach 1:
The patent performs preliminary detection of internal short-circuits by monitoring charge loss before temperature rise occurs. The system continuously calculates charge loss during charging and discharging cycles, enabling early warning of internal short-circuit build-up (dendritic formation) before it progresses to the point where temperature detection would be necessary. This preliminary action provides advance warning time for preventive measures.
3Adaptability or versatility
If internal resistance measurement is used during standby state, then the detection coverage is improved, but the measurement availability deteriorates because terminal current is zero
Solution Approach 1:
The patent creates a universal charge loss detection method that functions in both active and standby states. During active states, the system measures charge flow during charging and discharging. During standby states, the system measures charge loss by comparing state of charge before and after a monitoring period. This multi-functional approach allows continuous detection coverage across all battery operational states without requiring terminal current flow.
Data Source
AI summary
A battery management system (BMS) for early detection of a battery cell internal short-circuit. The BMS includes a memory, one or more processing units, and a machine-readable medium on the memory. The machine-readable medium stores instructions that, when executed by the one or more processing units, cause the BMS to perform numerous operations of a method for early detection of the battery cell internal short-circuit.