Research On Integrated Thermal Management System Of Pure Electric Vehicle Based On Phase Change Materials

At present,the battery performance of pure electric vehicles is closely related to the working temperature.The high or low temperature environment will seriously weaken the performance of the battery and reduce the service life of the battery.It is of great significance to study the heat management system of pure electric vehicles.Due to the heat storage and exothermic characteristics of phase change materials,phase change materials can provide appropriate heat management effect in high and low temperature environment.However,due to the restriction of phase change temperature or dosage of phase change materials,they are limited in use at high temperature and still need liquid cooling;therefore,the following research work of integrated heat management system based on phase change materials is carried out in this paper.(1)The heat generation principle and heat transfer process of battery and drive system of pure electric vehicle are analyzed.According to the battery thermal management requirements,the phase change materials were selected and the initial consumption was estimated.Based on AMESim software,the integrated thermal management model combined with phase change materials is built,and the parameters of phase change materials are optimized through simulation.The best comprehensive effect is obtained when the phase change temperature is 35℃ and the heat storage is 90%.(2)According to the working mode of battery and motor thermal management,the control strategy of integrated thermal management is proposed.The control strategy is optimized according to the principle of optimal temperature control effect and optimal energy consumption by using the method of multiple data comparison under multiple driving conditions.The optimal opening temperature of phase change heat dissipation cycle,battery strong heat dissipation cycle and motor heat dissipation cycle were determined as 33℃、40℃ and 50℃.(3)Compared with the common thermal management system in high and low temperature environment.The results show that the battery temperature can be stabilized below 37℃ at high temperature,which is at least 2.6℃ lower than that of ordinary thermal management;at low temperature,when the phase change material is liquid,the battery temperature can be increased by at least 16.4℃,which can reduce the lowtemperature internal resistance loss by at least 0.84%;when the phase change material is solid,the battery temperature can be increased by at least 1.3℃.An integrated thermal management that is a combination of liquid cooling/heating and PCM cooling/heating is proposed in this thesis.Both cooling under high temperature and heating under low temperature can be carried out in our proposed method.Not only is the structure optimization model of integrated thermal management system combined with phase change materials constructed,but also the logic threshold control strategy of integrated thermal management system based on optimization is provided,which proves that the thermal management system combined with phase change materials has better thermal management effect,lower energy consumption and better comprehensive effect.