Estimating the state of charge of lithium batteries based on fractional-order sliding-mode observer

This paper considers estimating the state-of-charge (SOC) for lithium-ion batteries, that utilizes a fractional-order (FO) sliding-mode observer (SMO) is investigated. The capacity loss and deterioration resistance can be estimated by the FO SMO. Based on Mittag-Leffler stability theory, the FO SMO is designed and analyzed. The convergence property about FO SMO is shown by utilizing the Lyanunov-Krasovskii function. A key analysis technique is enabled by proposed a fundamental boundedness lemma. The proposed method is easily applied to SOC in order to illustrate robust control properties against system's errors. The simulation examples are used to illustrate effectiveness of the proposed control scheme.