Research On Control Strategy Of Heat Pump Air-conditioning System For Electric Vehicles

Compared with PTC heater which is used by electric vehicle(EV)currently,the heat pump air-conditioning system(HPACS)could increase the driving range of electric vehicles.The control strategy of HPACS for electric vehicles has been researched in this paper.The research includes: experimental study of the heating performance of the HPACS,establishing and verification of the HPACS,research on automatic control strategy of heat pump air conditioning system for electric vehicles,simulations of indoor and outdoor heat exchanger effects on heating performance with different wind speed,the design of hardware and software design for compressor speed control based on single-chip.The thermodynamic properties of the heat pump air conditioning were analyzed on the basis of the heat pump cycle theory and the heating performance of the HPACS under different ambient temperature was analyzed.The simulation model of a HPACS for electric vehicles was built by AMESim.The simulation values and experimental values of the HPACS under heating mode were compared.The correctness of the simulation model was verified.The compressor speed control strategy of HPACS for EVs was researched.The compressor speed,the system heating capacity,the power consumption of compressor and the COP under on-off,PID or fuzzy control were analyzed.The simulation results show that compressor on-off control mode is fluctuate violently,while the PID and fuzzy control compressor speed change is slow;the power consumption of compressor is reduced by 14.53% than on-off control and by 2.738% than PID control;the COP under fuzzy control is higher than on-off and fuzzy control.In order to improve the adaptive performance of the HPACS under different environmental conditions,an adaptive fuzzy controller was designed.The indoor and outdoor heat exchanger with different wind speed on the performance of the HPACS were analyzed by simulation.The simulation results show that the mass flow rate decrease,the power consumption of compressor decrease obviously,the system heating capacity,the heat exchange of outdoor heat exchanger and the COP increase slightly with the increase of indoor heat exchanger fan air volume.The change of the system heating capacity and the heat exchange of outdoor heat exchanger are not obvious,the mass flow rate and the power consumption of compressor increase obviously,but the COP decrease with the increase of outdoor heat exchanger fan wind speed.Finally,the hardware and software for compressor speed control were designed based on single-chip,including temperature measurement circuit,display circuit,the electric compressor drive control circuit and buzzer alarm circuit.And C language program is designed for the controller.