Alternative Approach to In Operando Impedance Estimation in Vehicular Power Networks

Knowing the current State of Charge (SoC) of a battery is a critical task in electric mobility. Precise knowledge can improve range predictions, help to derive plans for best remaining usage, and assure the availability of security measures. Lithium ion batteries have proved their potential within the last years and are prospects to be a feasible solution for energy storage in automotives. Due to their characteristics, alternatives to open circuit voltage (OCV) based methods are required to estimate the SoC. This paper presents a new method to calculate a dynamic synchrophasor, in the case of superimposed signals. The method has been designed for impedance calculation in vehicles, as it accounts for operando superimposed disturbances in the on-board power supply nets by approximating them with a truncated Taylor series in order to suppress their influence on the impedance estimation results. Furthermore, the time vector is not required to feature uniform sampling frequency. In the given usecases, the accuracy of SoC estimation was increased by 20%, and the effect of non-uniform sampling frequency was significantly reduced.