Online Identification of Li-ion Battery's Internal Resistance based on a Recursive Least Squares Method to Prevent Overvoltage/Undervoltage

리튬이온 배터리의 과전압/저전압을 막기 위한 회기 최소 자승법 기반의 실시간 내부 저항 추정방법

This paper proposes an on-line estimation algorithm of internal resistance of Li-ion battery based on the recursive least squares method to prevent the overvoltage and undervoltage casing degradation of life cycle of battery. An equivalent circuit model with single time constant is adopted, and under assumptions that the terminal voltage, current and SOC are measured accurately, the discrete time based nonlinear equation of the model can be converted to the linear equation which can be applied to recursive least squares method. Since the coefficients of the discrete time linear equation can be expressed by the parameters of the equivalent circuit model, it is shown that an internal resistance (Ri) can be estimated in real time using the least square method.