Robust Interval Observer Design with Error Bounds for Lithium-Ion Battery State-of-Charge Estimation under Hybrid Uncertainties

This paper addresses the hybrid uncertainties in state-of-charge (SOC) estimation for lithium-ion batteries and proposes a robust interval observer-based SOC estimation method. By constructing a second-order equivalent circuit model, we design an interval observer with dynamic error bounds and ensure its robustness against parametric perturbations and noise disturbances through Lyapunov stability theory and linear matrix inequality (LMI) optimization. Experimental results demonstrate that the proposed method achieves SOC estimation errors below 5.5% under the Urban Dynamometer Driving Schedule (UDDS) dynamic current profile. Furthermore, this study provides a novel solution to the modeling complexity caused by cell heterogeneity in battery packs. By treating heterogeneity as bounded disturbances and replacing traditional individual cell modeling with interval estimation, the computational complexity is significantly reduced.