Research On Electric Vehicle Air Conditioning System And Battery Low Temperature Heating Based On Heat Pump

Under the background of Peak Carbon Dioxide Emissions and Carbon Neutrality,electric vehicles have been supported by countries and industries all over the world,and the development momentum is very rapid.However,the driving range of electric vehicles is limited.How to extend the driving range of electric vehicles by optimizing the energy consumption of various energy-consuming subsystems of electric vehicles under the limited battery capacity is one of the main challenges that electric vehicle manufacturers try to overcome.The thermal management system of electric vehicles,as a major energy consumer,its ultimate goal is to reduce energy consumption while ensuring the performance of the thermal management system.This paper focuses on the electric vehicle air conditioning system and its control strategy,battery modeling and battery lowtemperature heating.The main research contents and results are as follows:1.The electric vehicle air-conditioning system model coupled with the passenger cabin is established,and the component-level and vehicle-level verifications are carried out,which proves that the proposed air-conditioning system model has sufficient accuracy.Based on this model,a multistage constant compressor speed control strategy based on genetic algorithm optimization is proposed.Compared with the traditional on-off and PID controllers,the energy consumption of the multistage constant compressor speed control strategy is reduced by 17.5% and 7.5%,respectively.Compared with the EA control strategy,the energy consumption of the multistage constant compressor speed control strategy will be 5.8% lower.In addition,the multistage constant compressor speed controller has smaller compressor speed fluctuation than the EA controller,which proves its practicability in practical engineering.2.The indirect heat pump air conditioning system model is established,and the heat exchangers,electronic expansion valve,water pump,etc.used in the model are verified based on experiments.Based on the simulation calculation,the basic performance of the heat pump air conditioning system is studied.The performance of on-off,PID and MCCs control strategies in heat pump air conditioning system is compared.Compared with onoff and PID controllers,MCCs controller saves energy by 7.8% and 2.3% respectively,and COP increases by 20.6% and 3.0% respectively.3.The electrical model based on the first-order RC equivalent circuit model and the thermal model based on Bernardi equation are established.Then,HPPC experiments and low-temperature discharge characteristics experiments were carried out on the battery,and the parameters of the experimental results were identified to obtain the relevant parameters of the battery modeling.Finally,the established model is verified.The results show that the maximum RMSE of the battery voltage is 0.15 V and the minimum is 0.11 V,and the maximum RMSE of the battery temperature is 1.85 °C and the minimum is0.33 °C.4.The battery low-temperature heating model is established,and the lowtemperature heating of the battery is studied based on the priority of the crew cabin heating,the priority of the battery heating,and the simultaneous heating of the crew cabin and the battery.Using the heat pump air conditioning system to heat the battery pack from-10 °C to 0 °C and 25 °C,the battery pack capacity consumption is 2.26 Ah and 4.44 Ah,respectively,and a positive capacity gain of 0.48 Ah and 5.44 Ah is obtained.Calculated according to the voltage platform,0.15 k W.h and 1.74 k W.h,respectively.