Battery Thermal Runaway Detection Using Adaptive AC Impedance
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Solution Overview
Problem
Existing detection methods for thermal runaway in secondary batteries consume excessive power, especially when the battery is stopped, and are not efficient in suppressing power consumption while maintaining effective detection.
Innovation Solution
A thermal runaway sign detection device that includes a measurement unit to measure voltage fluctuations in two modes, a switching unit to switch to a second mode with reduced power consumption when the battery is stopped, and a detection unit that identifies thermal runaway by analyzing the rate of change in the real part of AC impedance at a specific frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous measurement is performed to detect thermal runaway signs, then detection reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by switching between first measurement mode (continuous measurement at normal operation) and second measurement mode (intermittent measurement at stopped state). The measurement unit performs AC impedance measurements periodically based on the operational state, detecting thermal runaway signs through rate of change analysis while reducing power consumption during stopped periods through less frequent measurements.
2Speed
If measurement frequency is increased to improve detection speed, then detection responsiveness is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the measurement frequency adaptive rather than fixed. The measurement unit dynamically adjusts the measurement frequency based on the operational state: using higher measurement frequency (first measurement mode) when the battery is operating to ensure fast detection, and switching to lower measurement frequency (second measurement mode) when stopped to reduce power consumption while maintaining adequate detection capability.
3Measurement precision
If comprehensive impedance analysis is performed across multiple frequencies, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement information needed for thermal runaway detection. Instead of performing comprehensive impedance analysis across multiple frequencies, the system focuses on measuring AC impedance at a specific frequency point and analyzing the rate of change of the real part. This extraction of critical parameters maintains measurement precision for thermal runaway detection while significantly reducing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively detects thermal runaway in secondary batteries while significantly reducing power consumption, even when the battery is stopped, by utilizing a dual-mode measurement approach and focused impedance analysis.
Implementation Method 1
a measurement unit that measures a voltage fluctuation in a first mode in which a number of times that a fluctuating current is output from the secondary battery and a voltage fluctuation of the secondary battery in response to the fluctuating current is measured
Data Source
AI summary
A thermal runaway sign detection device includes a measurement unit that measures a voltage fluctuation in a first mode in which a number of times that a fluctuating current is output from the secondary battery and voltage fluctuation of the secondary battery in response to the fluctuating current is measured is first number of times, and in a second mode in which the number of times is second number of times less than the first number of times. A detection unit detects a sign of thermal runaway in the secondary battery when a rate of change in a real part of an AC impedance obtained based on the voltage fluctuation measured by the measurement unit at the fluctuating current of a predetermined frequency at which an imaginary part of the AC impedance of the secondary battery calculated based on the voltage fluctuation becomes zero, is greater than a threshold value.