Lithium-Ion Cell Self-Discharge Detection via Balancing Charge
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Solution Overview
Problem
Existing battery management systems (BMS) face challenges in detecting abnormal self-discharge in lithium ion cells, which can lead to safety-critical states such as internal short-circuits and thermal runaway.
Innovation Solution
The method involves monitoring the battery charge per cell and utilizing the existing balancing function in the battery system to detect abnormal self-discharge. This is achieved by determining the charge drawn from or fed to each cell during balancing operations, calculating the total balancing charge, and assessing the balancing rate to identify cells with abnormally high self-discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the balancing function is used to detect abnormal self-discharge, then the detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by enabling the existing balancing function to serve dual purposes: its original function of equalizing cell charge and a new diagnostic function of detecting abnormal self-discharge. The battery management system evaluates balancing duration and balancing rate to identify cells with abnormal self-discharge characteristics, thereby improving detection capability without adding dedicated detection hardware.
2Reliability
If monitoring of battery charge per cell is implemented, then the reliability is improved, but the loss of energy increases
Solution Approach 1:
The patent implements feedback by continuously monitoring balancing parameters (balancing duration and balancing rate) and using this information to predict safety-critical states such as internal short-circuits and thermal runaway. The system provides feedback to the battery management system, which can then implement countermeasures to prevent catastrophic failures, thereby improving reliability through intelligent monitoring rather than continuous high-energy measurement.
Data Source
AI summary
A method for detecting abnormal self-discharge in a battery system by monitoring the balancing charge for each cell and a battery system which is configured to use this method are provided. The method makes it possible to predict the probability of the occurrence of a safety-critical state, for example, an internal short circuit, with the result that suitable countermeasures can be taken in good time.