Dual estimation of lithium-ion battery internal resistance and SOC based on the UKF

Lithium-ion batteries have been widely used in many fields. In order to make the battery work on good conditions, people should monitor its working states continuously. The two important working state of a battery are its internal resistance and the State of Charge (SOC). A dual estimation method of the internal resistance and the SOC based on the Unscented Kalman Filter (UKF) is proposed. The internal resistance is regarded as a parameter of a mathematical model, which reflects the relationship between the voltage and the SOC, the discharging rate and the temperature. The dual estimation of the internal resistance and the SOC are then done alternately with different UKF algorithms. Experimental results show that the proposed method is effective.