Battery Cell Fault Detection Using Subset Voltage Metrics
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Solution Overview
Problem
Existing battery controllers consume significant energy and resources to detect faulty battery cells by measuring impedance, which is inefficient and costly.
Innovation Solution
A battery controller measures cell voltages across subsets of battery cells and compares metrics to identify degraded or faulty cells without injecting a known current, using derivatives of voltage measurements to approximate impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional battery controllers inject a relatively large known current through a battery stack to measure impedance of each cell, then measurement precision is improved, but use of energy increases significantly
Solution Approach 1:
The patent extracts the impedance measurement function from the traditional current injection method. Instead of injecting current to measure impedance directly, the system uses voltage measurements during normal operation combined with derivative calculations to approximate impedance. This extraction eliminates the need for additional current injection while preserving detection capability.
Solution Approach 2:
The patent replaces the traditional electrical current injection method with a computational approach using voltage derivatives. By substituting the physical current injection mechanism with mathematical processing of voltage signals, the system achieves impedance estimation without the energy cost of active current injection.
2Measurement precision
If traditional battery controllers inject a relatively large known current through a battery stack to measure impedance of each cell, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the impedance measurement function from the traditional current injection method. Instead of injecting current to measure impedance directly, the system uses voltage measurements during normal operation combined with derivative calculations to approximate impedance. This extraction eliminates the need for additional current injection while preserving detection capability.
Solution Approach 2:
The patent replaces the traditional electrical current injection method with a computational approach using voltage derivatives. By substituting the physical current injection mechanism with mathematical processing of voltage signals, the system achieves impedance estimation without the energy cost of active current injection.
3Reliability
If battery cells are monitored frequently to detect degraded or faulty cells, then reliability is improved, but use of energy increases
Solution Approach 1:
The patent enables continuous monitoring during normal battery operation without interrupting energy supply. By using voltage measurements that occur naturally during battery use and processing them through derivative calculations, the system achieves continuous fault detection without the energy penalty of periodic current injection tests.
Solution Approach 2:
The system uses the battery's own operational voltage signals to perform self-diagnostics. The voltage measurements and their derivatives are computed from normal operating conditions, allowing the battery to monitor its own health without requiring external test equipment or additional energy input.
Data Source
AI summary
Techniques for identifying degraded or faulty battery cells of a battery stack are described. A controller measures cell voltages of a plurality of N battery cells arranged in series with one another in a battery stack. The controller arranges the plurality of N battery cells into subsets. The controller determines a metric across each of the subsets based on the measured cell voltages. The controller compares the metric of a battery cell subset to the metrics of other subsets. The controller identifies a degraded or faulty battery cell based on the comparison.