Liquid Cooled Battery Coupled (1D + 3D) Simulation Methodology for Thermal performance and Range Prediction of Electric Vehicle

Nowadays, Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) are becoming popular globally due to increasing pollution levels in the environment and expensive conventional non-renewable fuels. Li-ion battery EV’s have gained attention because of their higher specific energy density, better power density and thermal stability as compared to other cell chemistries. Performance of the Li-ion battery is affected by temperatures of the cells. For Li-ion cells, optimum operating temperature range should be between 15-35 °C [1]. Initially, small battery packs which are cooled by air were used but nowadays, large battery packs with high power output capacities being used in EV’s for higher vehicle performance. Air based cooling system is not sufficient for such batteries, hence, liquid coolant based cooling systems are being introduced in EV’s. Computational Fluid Dynamics (CFD) simulation can be used to get better insight of cell temperature inside battery. But it is complex, time consuming process involving multi-physics and exhaustive computations. Also, EV range is estimated by physical tests on a vehicle for predefined drive cycle loads where battery temperature affects the cell SoC drop rate and consequently the range of a vehicle. This test needs to be repeated for any variation in the input parameters which is again time consuming and resource demanding process. This paper describes the methodology which utilizes 1D and 3D simulation software which interconnects the electrical circuit, vehicle propulsion and CFD thermal simulation results to create coupled model of the battery system which enables us to obtain battery temperature distribution and its effect on vehicle range with minimal computational efforts eliminating the repeated full model thermal CFD calculations and physical tests for new drive cycle loads. This methodology can be utilized to expedite the battery development and performance improvement process to shorten product development to launch time.