A PWM Adaptive Sliding Mode Observer for Charge Control of Lithium Ion Battery

Abstract

An adaptive sliding mode control (SMC) based on PWM and an observer scheme for predicting the state of charge (SOC) of lithium-ion batteries is proposed. The control scheme is developed for a dc-dc buck converter used in regulated charge control of lithium-ion batteries. Unlike many estimation schemes where the converter’s output voltage is predetermined and the nonlinearities ignored, the proposed scheme estimates the buck converter’s output voltage, SOC, and nonlinearities in terms of errors in parameters. The stability of the proposed scheme is guaranteed by the Lyapunov method. The simulation was carried out in the Simulink in the MATLAB environment to transition from constant current charging mode to constant voltage charging mode. The results obtained from both modes in the Simulink in the MATLAB environment have shown that the dynamic control system of the SMC is asymptotically stable with excellent robust recovery features to sudden variations in input and un-modelled load.