Estimation of State of Charge of Batteries for Electric Vehicles

State of charge (SOC) can be applied in various fields characterized as an important parameter for estimating residual capacity state of battery. It is obtained from current or collected data, such as voltage, current and temperature as well. The accuracy of estimation of SOC of power battery can be essential and premise in designing the battery management system. Researchers in the fields shall take it an important and challenging task, requiring lots of work and energy, in order to improve the accuracy in estimation of SOC for eletric vehicles (EV). The SOC estimation tasks have made it great headway from classical and typical methods. This paper has proposed the shortcomings over various existed estimation methods and discussed the definition of SOC in details in the application. Study on the principle and application of the SOC estimation algorithm against many existing technical difficulties of SOC estimation algorithm for power batteries is very necessary. This paper analyzes the influence of charge and discharge rate, temperature, self-discharge and aging on SOC. It has important meaning for the further development of power battery SOC estimation.