Development of a Thermal Management System Model and a Capacity Fade Model for Li-ion Batteries in Electric Vehicles

Abstract

The thermal management system model for li-ion batteries in electric vehicles is developed. Convection heat transfer theories for the laminar and the turbulent flow are used. Both air cooled type and liquid cooled type thermal management systems are simulated and compared with experimental data. The open circuit voltage (OCV) and the ohmic resistance of the battery are given from experiments as map values indexed by the temperature and the state of charge (SOC). Constants for the activation loss are referenced from papers. Simulation results match well with experimental ones. The simulation model shows that finding efficient battery pack arrangement for the air cooled thermal management system is possible. The general battery model with the capacity fade mechanism due to the SEI film generation is also developed. Simulation results show that the capacity fade of the battery depends on the temperature. By including the battery model with the capacity fade mechanism to the thermal management system model of the electric vehicle, it will be possible to find optimum control methods to increase the state of health (SOH) of the battery.