SOC Estimation for Sodium-ion Battery Based on Fusion Algorithm

The accurate estimation of State of Charge (SOC) is crucial for ensuring the stable operation of energy storage system. This paper proposed a fusion algorithm for the SOC estimation of sodium-ion battery, which utilizes the ampere-hour integral method in the platform period and open-circuit voltage method with the online parameter identification in other periods. Firstly, the first-order RC Equivalent Circuit Model (ECM) is constructed. Secondly, the Forgetting Factor Recursive Least Squares (FFRLS) method is used to estimate the real-time parameters, which is aimed at mitigating the impact of environmental factors. Next, according to the increasing of the identified Uocv error in the platform period, a fusion estimation algorithm is proposed. Finally, we conduct experiments under DST and FUDS conditions. Experimental results demonstrate that the proposed algorithm has similar accuracy to UKF and EKF algorithm under DST or FUDS condition. The fusion estimation algorithm is about 32% and 88% faster than EKF and UKF algorithms.