Modeling Li-ion batteries for automotive application: A trade-off between accuracy and complexity

This paper presents a fast and effective approach to Li-ion battery performance modeling, particularly suited for automotive applications (i.e. HEV, PHEV, BEV). A second-order electrical equivalent circuit model made up by one voltage source, one series resistor and two series RC blocks (dual-polarization model), is here selected as the best trade-off solution for the task, addressing both acceptable levels of accuracy and complexity. While a lithium-iron-phosphate cylindrical battery cell is chosen for the purpose of the study, the presented procedure has broader validity and is mostly independent of Li-ion chemistry and/or cell format. The battery model is parametrized through a low time-consuming current pulse test, performed during both charging and discharging, at different state of charge levels. The temperature and load-current effects on the battery performance are not considered for simplicity and lightness of the presented model. Validation is carried out by comparing measured and simulated results during the dynamic current pulse test, showing a high level of agreement between the two.