The State and Parameter Estimation of an Li-Ion Battery Using a New OCV-SOC Concept

The open circuit voltage (OCV) is widely used to estimate the state of charge (SOC) in many SOC estimation algorithms. But the relationship between the OCV and SOC can not be exactly same for all batteries. Because the conventional OCV-SOC differs between batteries, there is a problem in that the OCV-SOC data should be measured to accurately estimate the SOC in different batteries. Therefore, the conventional OCV- SOC should be modified. In this paper, a new OCV-SOC that is independent of the battery conditions is proposed. Thus, problems resulting from the defects of the EKF can be avoided by preventing the OCV-SOC data from varying. In this paper, the SOC and battery capacity are estimated using the dual EKF with the proposed OCV-SOC.