Robust state-of-charge estimation for lithium-ion batteries: A high-order lumped disturbance compensation approach with a simple tuning strategy

Accurate state-of-charge (SOC) estimation is essential for ensuring the safe and reliable operation of lithium-ion batteries (LIBs). Effective disturbance compensation is a key factor in achieving robustness under real-world operating conditions. However, conventional SOC estimators often fail to account for the high-order dynamic nature of disturbances, leading to degradation in estimation accuracy. To overcome this limitation, this paper proposes a high-order lumped disturbance observer (HOLDO), which compensates for dynamic disturbances by modeling their successive time derivatives as extended states. System stability is rigorously established using Lyapunov theory, guaranteeing finite-error convergence. To facilitate implementation and enhance practicality, the proposed method employs a simple and efficient tuning strategy that achieves reliable performance with minimal adjustment. The robustness of the HOLDO is thoroughly validated under a variety of disturbance scenarios, and experimental results demonstrate that the proposed approach delivers effective disturbance compensation, achieving high SOC estimation accuracy and consistently yielding lower estimation errors compared with conventional observers.