A switching gain adaptive sliding mode observer for SoC estimation of lithium-ion battery.

A new state of charge (SoC) estimation method for lithium-ion battery that uses a Switching Gain Adaptive Sliding Mode Observer (SGASMO) is proposed. The purpose of SGASMO is to reduce the chattering of estimated results from the sliding mode observers (SMOs) and improve the estimation accuracy. First, the Dual Polarization (DP) equivalent circuit model is selected and its parameters are identified to provide a basis for the design of the new SMO. Second, based on the DP model, the nonlinear terminal sliding surface and continuous control law were introduced. And an improved switching gain equation was designed, which is adaptively adjusted according to the sliding mode surface equation. Thus, the SGASMO was realized, and the convergence of the proposed observer was proved by the Lyapunov stability theory. Finally, based on the test data of the self-built experimental platform, it is verified that the proposed SGASMO has less jitter in the estimated results and better estimation accuracy and robustness compared with the conventional SMOs and other types of mainstream improved SMOs. • A switching gain adaptive sliding mode observer (SGASMO) is proposed for SoC estimation. • The nonlinear terminal sliding mode surface is introduced to enable the tracking error to converge to the equilibrium point in finite time after the system reaches the sliding mode. • A continuous control law for SMO is designed to increase estimation accuracy and to reduce the chattering. • Adaptive adjustment of switching gain mitigates the impact of model errors on estimation accuracy and strengthens the robustness of the observer. [ABSTRACT FROM AUTHOR]