Excitation Pulse Influence on the Accuracy and Robustness of Equivalent Circuit Model Parameter Identification for Li-Ion Batteries

An equivalent circuit model (ECM) is a highly practical tool for simulating Li-ion battery behavior. There are many relevant studies which compare different ECM variants or suggest algorithms to extract model parameters from the experimental data. However little attention has been given to the battery tests used for identification of the ECM parameters. Therefore, we systematically studied the influence of experimental test pulse characteristics on the parameterized ECM accuracy. Test pulse duration and amplitude were varied along with the portion of the relaxation phase data used by the parameters fitting algorithm. That resulted in 168 parameter sets, each validated using 9 diverse current profiles including one based on a realistic drive cycle. The validation results prove that the impact of the test pulse choice on the parameterized ECM accuracy is great to the point it can overshadow the use of a higher order Thevenin model. By choosing the optimal parameter set the simulated voltage root mean square error was reduced to as low as 1.2 mV.