A State-of-Charge Estimation Method Based on an Adaptive Proportional-Integral Observer

Lithium-ion batteries play an important role in electric vehicles. Accurate and robust estimation of their state-of-charge is crucial for the efficient and safe operation of electric vehicles. To improve the accuracy and robustness of the estimation approach, an adaptive PI observer aim for state-of-charge estimation and parameters update simultaneously is proposed. Lyapunov stability analysis is employed to guarantee the stability of the observer. Meanwhile, a Thevenin equivalent-circuit model is established in Matlab/Simulink
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to verify the algorithm. Finally, the proposed method is validated by experiment results with urban dynamometer driving schedules. The results show that the proposed estimation using this adaptive PI observer is more accurate and robust than that using EKF or non-adaptive PI observer.