Adaptive secondary loop liquid cooling with refrigerant cabin active thermal management system for electric vehicle

Abstract

A thermal management system is required for an electric vehicle (EV) to achieve optimum efficiency while working under various environmental conditions. A battery thermal management system (BTMS) is essential for controlling the thermal behaviour of the battery and EV cabin temperature, especially during fast charging/discharging and in cold/hot environmental conditions, which affects battery electrochemical characteristics and EV performance. Most of the existing EV thermal management systems (TMS) are suitable for either cold or hot climates only. In order to address these issues, a secondary loop liquid cooling battery thermal management system with refrigerant cabin active thermal management system for EV is proposed in this paper. The proposed TMS is tested with a new European driving cycle in different weather conditions (−10 °C to 40 ° C). Based on weather and inside temperature of battery and cabin, compressor and coolant valves are controlled. In cold weather conditions, the high-temperature refrigerant flows through coolant pipes to heat the battery with latent condensation within 6 to 8 min, and the battery can be preheated from −10 °C to 10 °C with a battery heater. The positive temperature coefficient heater and blower are controlled to maintain the cabin temperature at the desired level. In hot weather conditions, battery temperature increases faster than the cabin, so the battery and cabin temperatures are controlled separately to keep the temperature at a desired safe level. The proposed topology effectively regulates temperature variations in between battery cells (less than 5 °C), reduces the energy consumption of the BTMS and predicts the battery and cabin temperature variations and controls thermal behaviour adequately. Sigma point Kalman filter algorithm is used to estimate the parameters of the battery system. Furthermore, the proposed control algorithm and parameter design are systematically developed to ensure acceptable performance.