A State of Charge Estimation Method Based on $H_\infty$ Observer for Switched Systems of Lithium-Ion Nickel–Manganese–Cobalt Batteries

Accurately estimating the state of charge (SOC) of the battery is the basis of battery management system. Based on a linear equivalent circuit model, this paper has introduced a switched battery model to model the complicated physical and chemical reactions properties. The SOC is determined by the battery electromotive force at a present battery state that is estimated through the
$H_\infty$
switched observer for dealing with the inexact or unknown statistical properties of the modeling and measurement errors. The observer design criterion is presented to ensure the
$H_\infty$
performance of the switched observer. Then, the proposed method is applied successfully to estimate the SOC by utilizing the current and terminal voltage. Finally, the experimental results have demonstrated that the proposed method can provide high accuracy and robustness for SOC estimation.