Co-Simulation Framework for Electro-Thermal Modeling of Lithium-Ion Cells for Automotive Applications

Battery packs used in automotive application experience high-power demands, fast charging, and varied operating conditions, resulting in temperature imbalances that hasten degradation, reduce cycle life, and pose safety risks. The development of proper simulation tools capable of capturing both the cell electrical and thermal response including, predicting the cell’s temperature rise and distribution, is critical to design efficient and reliable battery packs. This paper presents a co-simulation model framework capable of predicting voltage, 2-D heat generation and temperature distribution throughout a cell. To capture the terminal voltage and 2-D heat generation across the cell, the simulation framework employs a high-fidelity electrical model paired with a charge balance model based on the Poisson equation. The 2-D volumetric heat generation provided by the charge balance model is used to predict the temperature distribution across the cell surface using CFD software. A co-simulation tool is designed to ensure the electrical and charge balance models designed in MATLAB and Simulink are synchronized with the thermal model implemented in STAR-CCM+. The electrical and thermal models are calibrated and validated using experimental data. The model output was compared to data collected in a controlled environment with the cell fixtured to emulate different boundary conditions. The model was exercised with various power levels and boundary conditions to simulate different operating conditions, such as an air-cooled or liquid-cooled battery pack, or the location of the cell within the battery pack itself.