Numerical analysis of 'On-Off' control thresholds and coolant flow rate for better performance of a Lithium-Ion battery thermal management system

Electric vehicles will become an inevitable part of future transportation, because of the increasing concerns of global warming and climate change effects, caused by gasoline and diesel vehicles. Lithium-ion cells are the primary candidates for energy storage in electric vehicles. Lithium-ion cells are sensitive to operating temperatures. Operating them beyond the optimum temperatures, reduces their lifetime and can lead to thermal runaway, at extreme conditions. Hence, a thermal management system is required. In this work, a simple 'On-Off' control is used and the upper and lower thresholds are optimized, to reduce the energy consumption and the temperature difference between the cells. 3 coolant flow rates are selected and are analyzed for each upper and lower threshold. A MATLAB Simulink model and spreadsheet are used for analysis. The models are validated by experiments. It is found that a control strategy of '32 degrees C to 35 degrees C', with a coolant flow rate of 0.67 kg s(-1), among the selected strategies, is better in reducing energy consumption and temperature difference. Running the cells at relatively higher temperatures, within the optimum range, helps in reducing energy consumption and temperature difference.