Modeling and identification of lithium-ion batteries for electric vehicles

The present paper describes the modeling of the energy-storage unit - a battery that consists of several lithiumion cells - at various modeling depths. Identification by means of frequency measurements at different operating points and subsequent verification in the time domain serve to identify both the modeling structure and the system parameters. For the frequency measurement the Electrochemical Impedance Spectroscopy (EIS) is used. The iterative character of the selected procedure is exemplified. On the basis of dynamical testing cycles, the accuracy of the battery model is verified even with high frequencies.