A Flexible Online State of Health Estimation Approach for Lithium -ion Battery

The estimation of state of health (SOH) for lithiumion batteries is critical to the safe and reliable operation of electric vehicles and other energy storage devices. To estimate SOH accurately and flexibly, this paper proposes an improved method based on incremental capacity (IC) analysis. It processes the initial IC data from constant current charging by double filtering, which greatly reduces the number of data needed to eliminate noise on IC curve, and also the voltage threshold for obtaining IC valuable data. Then the estimation of battery SOH is converted to the calculation of the area enclosed by the IC curve, voltage marking line and coordinate axes. In addition, the method of IC curve segmented analysis is adopted to make SOH estimation more flexible and fast. Experimental results show that the proposed approach can accurately estimate the battery SOH in different charging or discharging depths, and is suitable for batteries with different aging conditions.