Estimation of state-of-charge using cubature Kalman filter based on online model

The parameters of batteries are time-varying and non-linear in different working conditions, so the method using FFRLS is proposed to estimate the parameters of batteries online. Based on online estimation of battery parameters, the method using CKF is employed to estimate SOC instead of traditional EKF. During the change from nonlinear to linear, EKF only keep the first order accuracy, however, CKF can keep the third order accuracy. An experiment has been carried out to evaluate the performances of the proposed methods. Compared with the traditional EKF, CKF based on online model has better SOC estimation accuracy.