Battery Pack Thermal Runaway Detection From Voltage Modulation
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Solution Overview
Problem
Current automobile vehicle battery pack designs lack effective systems for detecting and mitigating short circuits and thermal runaway events, which can lead to exothermic reactions and potential ignition, especially within the 5-10 second period after a short circuit initiation.
Innovation Solution
A method involving the positioning of a battery pack in a vehicle, measuring cell voltages at a predetermined rate, identifying voltage decreases and temperature increases, calculating derivatives and power spectra, and initiating alarms and mitigation actions such as stopping charging or releasing pressure when thresholds are exceeded, along with using discrete wavelet transformations to analyze cell voltage signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cell voltage is monitored continuously at high sample rates to detect thermal runaway early, then detection precision is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic sampling rate adjustment based on battery operating conditions. The sampling rate increases when temperature or voltage thresholds are approached, and decreases during normal operation, optimizing both detection precision and energy consumption.
Solution Approach 2:
The system changes monitoring parameters (sampling rate, threshold values) based on battery state. During normal operation, lower sampling rates reduce energy consumption, while during critical phases (charging, temperature rise), higher sampling rates improve detection precision.
2Measurement precision
If complex signal processing algorithms are applied to cell voltage data to detect thermal runaway, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the voltage signal analysis into multiple processing stages: raw voltage measurement, derivative calculation, spectral analysis, and threshold comparison. Each stage processes only necessary features, reducing overall computational complexity while maintaining detection precision.
Solution Approach 2:
The patent replaces complex mechanical sensor systems with electrical signal processing. By using derivative calculations and power spectrum analysis of voltage signals, the system achieves thermal runaway detection without additional physical sensors, reducing device complexity.
3Reliability
If mitigation actions are initiated immediately upon detecting thermal runaway indicators, then safety is improved, but false alarms increase
Solution Approach 1:
The patent implements feedback mechanisms where detected thermal runaway indicators trigger additional verification checks before mitigation actions are executed. The system continuously monitors multiple parameters (voltage, temperature, their derivatives) and requires consistent abnormal patterns before initiating safety responses, reducing false alarms while maintaining safety.
Solution Approach 2:
The patent performs preliminary analysis of voltage derivatives and power spectra before triggering mitigation actions. By calculating dV/dt and analyzing power spectrum characteristics in advance, the system can distinguish between normal voltage fluctuations and genuine thermal runaway indicators, improving safety response accuracy.
Data Source
AI summary
A method for detecting thermal runaway of a cell includes: positioning a battery pack having multiple cells in an automobile vehicle; measuring a cell voltage of the multiple cells at a predetermined sample rate; and identifying if the cell voltage decreases and modulates coincident with a cell surface temperature increase indicating initiation of a cell short.