Battery Balancing Compensation for Internal Short Detection
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Solution Overview
Problem
Existing battery management systems face challenges in accurately detecting internal short circuit faults in batteries without voltage imbalances, as balancing operations mitigate the voltage differences necessary for fault detection.
Innovation Solution
A battery management system that includes a battery monitor, balancer, and control circuit to detect no-load voltages, compensate for balancing capacity, and compare voltage differences with a threshold to identify internal short circuit faults, even in the absence of voltage imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If balancing operation is performed to mitigate voltage imbalances between batteries, then voltage balance between batteries is improved, but the ability to detect internal short circuit faults deteriorates because voltage imbalances are eliminated
Solution Approach 1:
The system performs balancing operations in advance to maintain voltage stability, but before doing so, it pre-calculates and stores the expected voltage values after balancing. This allows the system to maintain voltage balance while preserving the ability to detect faults by comparing actual post-balancing voltages with the pre-calculated expected values, thus resolving the contradiction between maintaining voltage balance and detecting internal short circuits.
2Measurement precision
If voltage imbalances are used to detect internal short circuit faults, then fault detection accuracy is improved, but voltage balance between batteries deteriorates
Solution Approach 1:
The system introduces an intermediary approach by using a virtual reference voltage (expected voltage after balancing) as a mediator between the actual voltage measurements and the fault detection logic. This virtual reference allows the system to detect faults based on voltage deviations from the expected balanced state without actually maintaining harmful voltage imbalances, thus achieving both accurate fault detection and voltage balance.
3Stability of the object's composition
If balancing operation is performed frequently to maintain voltage balance, then voltage stability is improved, but system complexity increases due to additional control operations
Solution Approach 1:
The system implements a self-service mechanism where the control circuit automatically calculates expected voltages after balancing and performs fault detection without requiring external intervention or complex additional control operations. The system uses its existing voltage measurement capabilities and balancing operation data to autonomously maintain voltage stability and detect faults, minimizing the increase in system complexity while improving voltage stability.
Data Source
AI summary
A battery management system includes a battery monitor, a balancer and a control circuit to control the balancer. The control circuit determines a first voltage value indicating a no-load voltage of each battery, compensates the first voltage value of each battery using a balancing capacity of each battery by a balancing operation for a latest reference time, determines a voltage deviation or a difference between the compensated first voltage value of each battery and a reference voltage value, and detects an internal short circuit fault in each battery by comparing a change amount of the voltage deviation of each battery for the reference time with a threshold.