Research On The Integrated Thermal Management System Of Electric Vehicles Based On Heat Pump

New Energy vehicles have developed rapidly due to the promulgation of relevant national policies,in which EV has become the favorite among new energy vehicles because of its advantages of zero emission,low noise and energy saving,but its development is influenced by the capacity of the battery and its characteristics at high/low temperature.In all accessories,the air-conditioning system is the largest power consumption,because of the cancellation of the engine layout,so pure electric vehicles in low-temperature heating usually used PTC heater.The correlation analysis shows that the total energy consumption of heating by PTC is 30% ～ 40%,so the heating method has a great impact on the endurance of pure electric vehicles,therefore,it is very important to develop an integrated high-efficiency thermal management system for pure electric vehicles.In this paper,the functions of the thermal management system are analyzed and the optimum temperature range is determined.Based on the comparative analysis of the thermal management schemes of the traditional vehicle and the pure electric vehicle,an integrated vehicle thermal management system is established,and its working mode and loop are determined.The cycle principle of the air conditioning system is analyzed,and the cold/heat load model is established for the vehicle interior environment,the influence of temperature on the motor is explored,the whole vehicle and the thermal management system model are built in AMESim,the control strategy of the key parts of the thermal management system is developed based on MATLAB/Simulink environment,and the different temperature scenarios are established,the performance of the system at high temperature and the difference of different heating methods at low temperature are analyzed to verify the effectiveness of the system and its control strategy.Firstly,the functional requirements and the optimal operating temperature range of each subsystem of the pure electric vehicle are defined,and the heat management configuration of the traditional vehicle and the current pure electric vehicle is analyzed and summarized,aiming at the problems of high energy consumption and low efficiency of heat management system in low temperature heating of vehicles,a hybrid heating scheme of “Heat pump system + PTC”is put forward,at the same time,the scheme of“Motor/electronic control system waste heat recovery”is developed to realize the secondary energy recovery,and the system priority rules are established according to the integrated vehicle heat management scheme In this paper,the thermal load model of different temperature scenarios in vehicle interior environment is established,which is used as the target reference for subsequent compressor control A temperature sliding mode outer loop control strategy based on reaching law and a feed-forward-feedback inner-loop compressor speed compound control strategy are established PTC layered control algorithm based on temperature difference of controlled system is established and developed in MATLAB/Simulink environment.Pure electric vehicle and thermal management system model under AMESIM software is established and different temperature scenarios are set up,the simulation verifies the feasibility of the vehicle thermal management system based on the heat pump system and the developed control strategy.