Research And Implementation Of Heating Control Strategy Of Air Conditioning Under Low Temperature Condition For Pure Electric Vehicle

In recent years,the state vigorously advocates new energy vehicles,pure electric vehicles ushered in an unprecedented development opportunity.The air conditioning system of pure electric vehicle has important influence on the safety and comfort of pure electric vehicle.Based on a miniature pure electric vehicle,this thesis analyzes the status quo of the air conditioning system and control strategy of pure electric vehicles,and then researches and designs the heating control strategy of pure electric vehicles under low temperature conditions on the basis of heat pump air conditioning,aiming at the existing problems under low temperature conditions.By applying the fuzzy control strategy and the fuzzy-PID control strategy to the temperature control of each stage under the low temperature condition,the heating control strategy under the low temperature condition of pure electric vehicle air conditioning is realized.The main research contents of this thesis are as follows:1.The development status of the air conditioning system and its control strategy for pure electric vehicles is reviewed.By studying the development trend and application of the air conditioning system and control strategy of pure electric vehicles at home and abroad,the thesis analyzes the main problems of the air conditioning system of pure electric vehicles in heating,such as heating efficiency and heat pump starting at low temperature.2.Built the thermal load model of the air conditioning system of pure electric vehicles on the platform of Matlab/Simulink software.The heat production performance data of heat exchanger and PTC heater of heat pump system are obtained through performance test.Based on the experimental data,the heat load model of air conditioning system of pure electric vehicle is built.3.From the perspective of solving problems and conforming to the development trend,this thesis proposes a heating control strategy for the air conditioning system of pure electric vehicles under low temperature conditions.As the heating efficiency of the heat pump air conditioning system of pure electric vehicle is much higher than that of PTC heater,on the basis of making full use of the heat of the heat pump air conditioning system of pure electric vehicle,PTC heater is reasonably used for auxiliary heating.Inthis thesis,when specifically designing the heating control strategy under low temperature conditions,the low temperature conditions are divided into two parts:typical low temperature conditions and ultra-low temperature conditions.According to the typical low temperature working condition and ultra-low temperature working condition,different heating control strategies are adopted to control the compressor and PTC heater of the system so as to control the indoor temperature.After completing the design of the above research contents,in order to verify the feasibility and performance of the air-conditioning heating control strategy of pure electric vehicles under low temperature conditions,MATLAB modeling and simulation analysis and test and verification of the real vehicle test platform were carried out.In MATLAB modeling and simulation,the adjustment time of the air-conditioning heating control strategy of pure electric vehicles designed in this thesis under low temperature conditions is all controlled within 51 s,the overshooting temperature can be controlled within 2?,the steady-state error is 0.1? at most,which meets the initial control requirements.In the test and verification of real vehicle platform,the indoor temperature of the air conditioning heating control strategy of pure electric vehicle designed in this thesis is stable in the error zone of ±2% after the temperature is stabilized.The trend of temperature change in the adjustment process is similar to that in the simulation process,but the specific indoor data fluctuates in a small range.The test results show that the designed control strategy for air conditioning and heating of pure electric vehicle under low temperature condition meets the initial requirements and shows its practical application value in the control system of pure electric vehicle.