Sectionalized heating strategy for electric vehicles based on multi-heat-source integrated thermal management system in cold environments

The significant attenuation in discharge capacity of lithium-ion batteries and the marked increase in energy consumption for the thermal management system (TMS) at low temperatures dramatically reduce the range of electric vehicles (EVs) in cold climates. Developing an efficient and intelligent integrated thermal management system (ITMS) can fully recover the waste heat from the propulsion system and enhance the heating efficiency at low temperature, thereby efficaciously decreasing the vehicle heating energy consumptions. This paper regards the PTC heater, the air-source, the battery and motor waste heat as the heat source and proposes a multi-source ITMS architecture to decrease the comprehensive energy consumption of TMS. Firstly, a vehicle-level simulation model encompassing a physical-based integrated heat pump model, an electrothermal coupling model of battery pack, a propulsion system model, a cabin model, and a low voltage load system model is established. The numerical calculated models of heat exchanger and battery are calibrated by the actual experimental data. Secondly, on the basis of the devised ITMS, a segmented heating strategy (SHS) is developed according to the battery temperature with premise of ensuring the cabin thermal comfort. Finally, the sufficient and comprehensive analyses of the system heating performance under different ambient temperatures and driving cycles are conducted based on the model simulations. Compared with the traditional separate and semi-integrated TMS, the proposed ITMS incorporated with SHS operated in the environmental temperature of −7 °C after 2.2 h, the energy consumption can be lowered by 6.2 % and 3.7 %, respectively. Meanwhile, the proportion of energy consumption by the ITMS under highway driving conditions also could be distinctly reduced. The experimental results manifest that the developed heating scheme could conspicuously enhance the waste heat recovery capability of the ITMS, thereby effectively improving the EVs’ range in cold environments.