Battery Pack Degradation Detection via Passive Charging Duration
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Solution Overview
Problem
Existing methods fail to accurately identify the start of accelerated degradation in lithium-ion batteries used in electric vehicles, leading to unexpected loss of autonomy, as they do not account for sudden battery death and rely on linear or power law-based SOH estimation models.
Innovation Solution
A method that measures the duration of passive charging phases and calculates the rate of increase in these phases relative to a reference duration, determining a linear function representing the progression of this rate based on cumulative energy discharged, allowing for early identification of acceleration in battery degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear or power law-based SOH estimation models are used, then the calculation is simple, but the accuracy of identifying accelerated degradation is insufficient
Solution Approach 1:
The patent changes the parameter being monitored from direct SOH estimation to the duration of passive charging phase. By measuring how long the battery remains in passive charging mode to reach a predetermined state of charge, the method detects degradation acceleration through temporal parameter changes rather than relying on complex SOH calculation models.
Solution Approach 2:
The method implements feedback by continuously measuring passive charging duration, comparing it against reference values, and using this information to identify when degradation acceleration begins. This feedback loop enables real-time monitoring without requiring complex predictive models.
2Reliability
If complex monitoring methods are implemented to detect sudden battery death, then the detection accuracy improves, but the device complexity increases
Solution Approach 1:
The patent extracts the key diagnostic information from a specific phase of the charging process - the passive charging phase. By isolating and measuring only this phase's duration, the method obtains reliable degradation detection data without needing to monitor or analyze the entire charging process or implement complex sensor arrays.
Solution Approach 2:
The battery management system uses existing charging process data to self-diagnose degradation. The passive charging duration, which is already recorded as part of normal charging operation, is repurposed as a degradation indicator, eliminating the need for additional sensors or complex monitoring hardware.
3Reliability
If real-time monitoring of battery degradation is performed, then the vehicle autonomy management improves, but the computational load increases
Solution Approach 1:
The method uses simple, easily obtainable charging process data instead of requiring expensive or complex computational resources. The passive charging duration is a basic parameter already available from standard battery management systems, requiring minimal additional computational energy to process and analyze.
Data Source
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AI summary
Method (1) for identifying the start of the acceleration of the degradation of the state of health of a rechargeable battery pack, said pack being charged using a charging method comprising a dynamic charging phase and a passive charging phase, in the latter of which phases the start of the acceleration of the degradation of the state of health of the pack of rechargeable batteries is identified (13) depending on a linear function representative of the progression of the rates of increase in the duration of the passive charging phase, which rates are computed depending on the cumulative amount of energy discharged by the pack.