“Safety, energy saving and environmental protection” is the eternal theme of automotive technology development. In today's global energy crisis and environmental problems are becoming increasingly serious, new energy vehicles, represented by electric vehicles, have become the future development trend of automobiles. As one of the key technologies of electric vehicles, the safe and efficient use of batteries depends on the accurate estimation of battery status. The state of the battery can be divided into two categories, one can be directly measured, such as voltage, current, temperature, etc. The other category cannot be directly measured, but can only be estimated by certain methods, such as the state of charge SOC, state of health SOH and so on.