A novel State of Health estimation method for Lithium-ion battery in electric vehicles

To ensure safe operation of lithium-ion battery, precise estimation of its states like state of health (SOH) is indispensable. This paper proposes a novel SOH estimation method for lithium-ion battery in electric vehicle applications. When it's time to update battery capacity, the estimator extracts historical current and voltage data of last driving event and estimates open circuit voltage (OCV) based on affine projection algorithm. By means of the estimated OCV and the three-dimensional response surface OCV model, the SOH estimator gives the estimation result of the battery capacity. Experiments verify that the proposed estimation method is accurate and robust under different working conditions and different aging states.