Nonlinear Observer Design for RC Battery Model for Estimating State of Charge & State of Health Based on State-Dependent Riccati Equation

Abstract

This paper investigates a novel nonlinear observer design approach based on the State-Dependent Riccati Equation (SDRE) technique for estimation of the state of charge (SOC) and state of health (SOH) parameters of nonlinear RC battery model. Due to practical restrictions on direct measurement of SOC, we try to introduce effective and accurate observing scheme which excel estimation results. The estimation of SOC and SOH has a crucial role in applications involving rechargeable batteries. SDRE observer is an extended form of Kalman Filter (KF) estimator for nonlinear systems. In this paper, the SDRE-based observer has been proposed for nonlinear RC battery model which is widely used. The resulting observer has several advantages including a faster convergence, better accuracy, and simpler structure in comparison with most existing methods. The simulation results show the merits of SDRE filter in estimating of SOC and SOH.