Research on State of Power Estimation of Echelon-Use Battery Based on Adaptive Unscented Kalman Filter

An echelon-use lithium-ion battery (EULB) refers to a powered used in electric vehicles when the capacity is attenuated less than 80% and greater 20%. Aiming at degradation of performance EULB unclear initial value state energy (SOE), estimations power (SOP) an are not accurate. SOP estimation method based on adaptive dual unscented Kalman filter (ADUKF) proposed. First, second-order resistor-capacitance symmetry equivalent model (SRCSEM) established. Second, transformation (UT) introduced parameters estimated by ADUKF: (a) SOE filtering (AUKF) algorithm, that uses observation noise equation γk, Rk processes qk, Qk, (b) ohmic internal resistance (OIR) actual (AC) aforementioned which γθ,k, Rθ,k process qθ,k, Qθ,k. Third, working voltage OIR predicted using optimal estimation, estimated. MATLAB simulation results show decays 80%, 60%, 40%, 20% rated capacity, proposed algorithm regardless whether consistent with value, error EULB’s 3.28%, showing high accuracy. The this study can provide valuable reference for estimating parameters, help understand usage behavior retired batteries.