Battery Pack SOH Estimation Using Stress Parameters and Capacity Deviation
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Solution Overview
Problem
Battery packs experience capacity degradation due to solid-electrolyte interphase (SEI) thickening and mechanical stresses, leading to performance deterioration and limited cycle life, necessitating an accurate estimation of State of Health (SOH) for timely replacement and prevention of over-charging/over-discharging.
Innovation Solution
A system and method that involves receiving operational parameters from battery cells, determining initial and discharge-based SOH, selecting stress parameters for State of Charge (SOC) ranges, and transmitting an ideal SOH signal when a deviation parameter exceeds a threshold, utilizing a processor and transceiver within a battery telematics unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If multiple charging/discharging processes are performed by the battery pack, then the battery provides energy for repeated operations, but the SEI layer thickens leading to gradual capacity loss
Solution Approach 1:
The system performs preliminary estimation of State of Health (SOH) by analyzing operational parameters and stress parameters before significant capacity degradation occurs. This allows proactive identification of SEI thickening effects and mechanical stress impacts, enabling timely battery replacement or maintenance before cyclable lithium loss becomes critical.
Solution Approach 2:
The system continuously monitors operational parameters (temperature, voltage, current) and stress parameters during charging/discharging cycles, providing real-time feedback on battery health status. This feedback mechanism tracks SEI layer development and mechanical stress accumulation, allowing dynamic adjustment of charging protocols or early warning of capacity loss trends.
2Productivity
If mechanical stresses are exerted on electrodes during charging/discharging, then the battery operates through volume changes, but particle fracture and breaking electronic network pathways occur
Solution Approach 1:
The system estimates SOH by analyzing stress parameters associated with mechanical loading before particle fracture and electronic network breakdown become severe. This preliminary assessment detects early signs of electrode structural degradation, allowing preventive maintenance before productivity gains from high-rate operation cause irreversible reliability loss.
Solution Approach 2:
The system continuously monitors operational parameters including temperature, voltage, and current to assess mechanical stress on electrodes during charging/discharging. This real-time feedback correlates stress patterns with SOH degradation, enabling dynamic control of charging rates to maintain electrode structural integrity while optimizing productivity.
3Device complexity
If a simple SOH estimation method is used, then the system complexity is reduced, but measurement precision of battery health status deteriorates
Solution Approach 1:
The SOH estimation system is segmented into distinct functional modules: operational parameter acquisition, stress parameter analysis, SOH calculation, and result output. This modular segmentation maintains measurement precision through specialized processing in each module while reducing overall system complexity through standardized interfaces and independent optimization of each component.
Solution Approach 2:
The system introduces intermediate stress parameters as mediators between operational parameters and final SOH estimation. These stress parameters (thermal, electrical, mechanical) serve as intermediary variables that capture the complex degradation mechanisms, enabling accurate SOH measurement without requiring direct observation of internal battery state, thus maintaining precision while managing complexity.
Data Source
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AI summary
A method (400) and system (105) for estimation of State of Health (SOH) of a battery pack (110) is provided. The method includes determining a first SOH (410) utilizing a set of operational parameters and a first set of stress parameters and a second SOH (415) based on a determined discharge capacity. Utilizing the first and the second SOH (425), determine a second set of stress parameters of the battery pack. The method includes determining a third SOH (435) of the battery pack based on at least one selected second set of stress parameters and the set of operational parameters and determining a deviation parameter based on the first and the third SOH. Thereafter, the method includes transmitting an ideal SOH signal (445) to one of a server and a user device in response to the determined deviation parameter being greater than a pre-defined threshold.