Electro-Thermal Simulation Methodology for Battery Thermal Management System (BTMS) Performance Evaluation of Li-Ion Battery Electric Vehicles

In the recent years, Hybrid and Electric Vehicles (EVs) have gained attention globally due to conventional non-renewable fuels becoming expensive and increasing pollution levels in the environment. Li-ion battery EV’s are most popular because of their better power density, spe. energy density and thermal stability. With the advent of battery EV’s, concerns regarding thermal safety of vehicle and its occupants has grown among the prospective customers. Temperature plays an important role in the performance of the Li-ion battery which includes cell capacity, charge output, vehicle range, mechanical life of the battery etc. For Li-ion cells, optimum operating range should be between 15-35 °C [1], and all cells must also be maintained within a ±5 °C variation band. Computational Fluid Dynamics (CFD) simulation can be used to get better insight of cell temperature inside battery. But CFD simulation process is complex, time consuming involving multi-physics and exhaustive computations. This paper describes the simulation methodology which eliminates repeated CFD analysis and physical tests. With the help of CFD thermal results and Equivalent Circuit Model (ECM) of the battery, Reduced Order Model (ROM) for Battery Thermal System is created which can calculate cell temperatures during the drive cycle operating condition. ECM is obtained using Hybrid Pulse Power Characterization (HPPC) test results of the cell. Current methodology is developed using commercial 3D CFD software, 1D simulation software and standard drive cycle input conditions data. It provides medium fidelity digital model of given battery system which can be further used for multi-physics study, battery cooling system design and power utilization study.