The present invention discloses an SOC (
state of charge)
estimation method. According to the method, a battery OCV-SOC relationship module, a parameter acquisition module, an offline identification parameter value, a parameter discrete
state space model, a battery parameter
online identification module, a battery dynamic parameter update module and a battery SOC
estimation module. The method includes the following specific steps that: 1, a
discharge-standing experiment is performed, an OCV-SOC relationship expression is obtained through fitting, parameter values in an
equivalent circuit model are identified; 2, a battery second-order RC
system discrete
state space model is established, and the battery
model parameters are identified online and dynamically updated; and 3, the SOC of a battery is estimated online. With the method of the invention adopted, the defects of inaccuracy and accumulative error of the initial value of the SOC of a battery of in an
ampere-hour integration method can be eliminated. The method is applicable to the dynamic change of the characteristics of the battery, can improve the accuracy of SOC online
estimation and can be widely applied to the electric vehicles and storage battery
management system field. The method has the advantages of high battery model precision, fast convergence, high stability and high reliability.