A mixed SOC estimation algorithm using enhanced OCV reset and the DCIR iterative calculation reset

In this paper, a mixed algorithm is proposed to improve SOC estimation accuracy for large-capacity Li-ion battery by using advantages of Coulomb counting method, DCIR reset method, and enhanced OCV reset method. Because each method has drawbacks of accumulated SOC error during the operation in EVs, the optimal mixed algorithm is presented. Also, the weighted current value I
_DC
based on the mathematical analysis of the second-order RC ladder model is calculated and then it is applied to methods respectively. The proposed algorithm is verified by the experimental results based on the 27 Ah LiPB. As a result, the SOC RMSE of the proposed algorithm is decreased about 2.22% by compared with the Coulomb counting method.