Nonlinear Optimization Strategy for State of Power Estimation of Lithium-Ion Batteries: A Systematical Uncertainty Analysis of Key Impact Parameters

The state of power (SOP) of lithium-ion batteries plays an essential role in power distribution of electric vehicles and energy storage stations. However, due to the highly nonlinear dynamic behaviors and the parameter errors, accurate and reliable SOP estimation is always difficult. This article develops an optimization strategy to estimate SOP, in which the multiple constraints are simultaneously considered and the nonlinear equivalent circuit model (ECM) is directly adopted. On basis of it, the effects of single parameter uncertainty and multiparameter uncertainty are thoroughly investigated. The results show that compared to the conventional method, the proposed method could provide more reliable SOP estimation during the whole operation range. Moreover, different uncertainty sources have different effects on estimation results, not only the estimate values but also the constraint regions. This is the first time to directly employ the nonlinear form of ECM parameters in the SOP estimation and provide a comprehensive investigation of various uncertainty sources.