Case Study on Optimized Cooling System Concept for Electric Compact-SUV with Indian Environmental Conditions

With the rising emission level in Indian cities, the focus on pure battery electric vehicle is increasing also in India. The Government of India his also focusing on preparing right policies like FAME-2 to promote the acceptability of EV's by providing subsidies as well as creating the required infrastructure. The environmental conditions in India is much different than other developed countries of Euro, China etc. The max. temperatures in India can go up to 55℃ in the hottest summer time, while during winters temperature can go up to <-25℃ in the northern Himalia region. In these conditions the cooling system of the electric-powertrain components like E-Machine Battery pack etc have to be protected for worst case scenarios specific to Indian conditions. Major cost driver of EV's lie in the HV battery packs and it is very important for acceptability of EV's that the Battery is maximized. With fast discharging and charging phenomena of battery pack required in automotive application can lead to uneven temperature distribution across the battery pack. Battery ageing gets accelerated with cell temperatures exceeding 40-50 ℃. Additionally in ambient temperatures below 0℃ the battery SOC reduces drastically leading to much reduced driving range. The HV battery life being so much temperature dependent, makes the role of right thermal management very important. In the presented work an electric compact SUV from Indian market has been selected for the study. The integrated thermal management for complete vehicle has been evaluated including the vehicle HVAC system and electric powertrain components. The refrigerant circuit along with chiller extracts heat from the hot coolant. For heating the coolant high voltage electric heater have been used with by-pass from the chiller and front radiator. The electric powertrain components like E-machine, Battery pack, Power electronics etc. are cooled by the liquid coolant (water-ethylene glycol). All worst case ambient environmental conditions were evaluated along with worst case vehicle duty cycle and maneuvers. All simulations were done in 1D domain using GT Suite software where the simulation model was validated with actual vehicle test data. This integrated cooling system model was used to optimize the whole coolant circuit by performing the right sizing of heat-exchanger, refrigerant system etc.