SAE International Design of Efficient Air-Conditioning Systems for Electric Vehicles 2013-01-0864

Among all the auxiliary components in conventional and electric vehicles, air-conditioning (AC) systems present the highest energy consumption. In fully electrical vehicles (FEVs), the heating of the cabin becomes an additional challenge as there is less waste heat available. Therefore, a careful design of the air-conditioning system and of the operation strategies is necessary to reach a reasonable FEV autonomy without compromising the thermal comfort. This paper presents a tool for the design, analysis and optimization of an efficient air-conditioning system for an electric minibus. It consists of dynamic models of each component of the system that have been developed and fully validated individually. Finally, they have been coupled together to simulate the overall vehicle performance of the vehicle in MATLAB-SIMULINK. The core of the system is a water-to-water reversible heat pump with a variable speed compressor. The internal water loop connects the heat pump to the air-coolers inside the cabin while the external water loop is integrated within the heat rejection system of the power electronics. An automatic control system regulates the speed of the compressor, the blowers and the circulation pumps to reach thermal comfort. The power consumption has been analysed under different working conditions and control settings using the overall vehicle model. The latter is a powerful tool not only to design and select MAC equipment, but also to find the most efficient operation strategies.