Multiple Characteristic Variables Comprehensive SOH Evaluation Based on Fuzzy Logic for Lithium-ion Battery

Multiple Characteristic Variables Comprehensive SOH Evaluation Based on Fuzzy Logic for Lithium-ion Battery

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[Introduction] (The SOH(State of Health) evaluation of lithium-ion batteries is difficult to meet the on-board environment requirements of electric vehicles because of the dispersion of evaluation results was caused by the inconsistent characteristics of batteries.[Method] To solve the problem, the corresponding changes of open circuit voltage curve, pulse voltage response and incremental capacity curve of typical energy storage component NCM battery during life cycle test were analyzed.6 characteristic variables which were closely related to the battery capacity loss were selected, and a comprehensive SOH evaluation method based on fuzzy logic was proposed.

In this method, membership function was rawafricaonline.com used to establish the relationship between SOH evaluation sets and variable indicators, and analytic hierarchy process based on correlation coefficient was used to determine the weights of variable indicators that have an impact on the evaluation results.Finally, the validity of the proposed u11-200ps method was verified by four NCM-21700 batteries that completed the life cycle test.[Result] The results show that the method can effectively reduce the dispersion of SOH evaluation, and the average error is not more than 3% as well as the maximum error is no more than 5%.

[Conclusion] This work provides some guidance for further study on state of health evaluation of lithium-ion batteries.