Dynamic Correction Strategy of SOC Based on Discrete Sliding Mode Observation 2019-01-1312
Battery state estimation is one of the important decision parameters for lithium battery energy management. It plays an important role in improving battery energy utilization, ensuring battery safety and enhancing system reliability. This paper is proposed to provide an dynamic correction of the SOC in the full working condition, including static condition and dynamic condition.Based on the ampere-hour integral method, the current SOC value of the battery is calculated. Under the static condition of the battery, the open circuit voltage of the battery is directly collected.Under the dynamic working condition, the open circuit voltage of the battery is estimated by the sliding mode observer. Based on the deviation between the calclulated and estimated values of the open circuit voltage and the value of the open circuit voltage corresponding to the current SOC, the current coefficient of the time integral is dynamically corrected by PI strategy. The research shows that the proposed strategy can effectively correct the deviation of SOC in the initial process and the discharge process, and avoid the problem that the existing "open circuit voltage + ampere-hour integral" cannot dynamically correct the SOC deviation.When the SOC is calculated to have an upward deviation of 8% or a downward deviation of 5%, the sliding mode observer can be quickly calibrated.