Temperature-Dependent Thévenin Model of a Li-Ion Battery for Automotive Management and Control

This paper focuses on the analysis of Li-ion battery behavior at different temperatures through the Thévenin electrical circuit model. First, evaluations for both steady-state and dynamic battery applications are provided, then an overview of the different battery models to describe their dynamic behavior is analyzed. The focus is dedicated to the double polarization Thévenin-based equivalent circuit model since it represents an optimal trade-off between accuracy and computation effort, which justifies its implementation in a Battery Management System (BMS) for automotive real-time monitoring and control. The model is composed of a voltage source, one series resistor and two series RC blocks. The Hybrid Pulse Power Characterization test (HPPC) is performed inside a climatic chamber to extract the electrical parameters of the model and their dependency from both temperature and State Of Charge (SOC). The load-current effects on the battery performance are not considered for the simplicity and lightness of the presented model. The presented procedure has broader validity and is mostly independent of cell format and Li-ion chemistry, despite a specific cylindrical battery cell is chosen for the study. The results of the test are suitable for the future implementation of a proper algorithm for SOC and State Of Health SOH estimations. Moreover, they provide an effective electrical and thermal characterization of the cell to evaluate the heat generation rate inside the cell.