SoC Estimation in Li-ion Batteries Exploiting High-Frequency Model Properties

This paper explores the use of the high-frequency voltages and currents at battery terminals for the estimation of the State of Charge (SoC). The proposed approach will analyze the viability of using both the switching harmonics injected by the power converter used for the interface of the battery as well as an additional high-frequency signal excitation. Over the high-frequency model of the battery, the variation of the model parameters with respect to the fundamental current and SoC value is analyzed. Using the variation of one of the model inductive terms, a SoC estimation procedure is presented. The proposed methodology can be later extended to analyze the influence of other important values, as the State of Health (SoH) and cell temperature.