Research And Design Of Dual Source Heat Pump For Electric Vehicles

Air conditioning system,which is important for improving the comfort of cabin environment,is one of the essential component of modern vehicles.For electric vehicles,concerning the problem that Cabin,battery and driving motor has different thermal requirements and air conditioning system consume a lot energy in winter,a dual-source heat pump system that can absorb heat from driving motor and air was put forward in this study.The performance and control system of the dualsource heat pump were studied as well.Firstly.The thermal characteristics and requirements of the cabin,power battery and driving motor were studied.Based on the study,A dualsource heat pump system was put forward,which has the following features:(1)Cabin cooling in summer;(2)Cabin heating in winter;(3)Motor thermal management and heat recovery in winter;(4)Heat exchanger defrost in winter;(5)Cabin dehumidifier in winter;(6)Battery thermal management.Secondly,concerning the demand for the control system of the dualsource heat pump,a control system was designed with Altium Designer / Matlab / Simulink.Including: The development of the hardware based on Freescale MC9S12XEP100;Research of the control strategy;Design of the software;Development of CCP calibration system,which can be used for system development,testing and calibration;Hardware in loop test on dSPACE platform.Thirdly,a test bench of dual-source heat pump was built,and the performance of system was tested in an environmental chamber including the expansion valve opening test,performance test with simulated heat,temperature rise test.The results demonstrate that,there is an optimal expansion valve opening to obtain the optimal COP;the heat pump system can significantly improve the heating efficiency of the automobile heat pump.Finally,a simulation model was established based on AMESim and verified by experiment result.Based on the model,the performance and control strategy of the dual-source heat pump in Urban Dynamometer Driving Schedule were studied as well.The results demonstrate that,in cooling mode,the dual-source heat pump could meet the need of cabin cooling and battery cooling,and battery cooling has small impact on the cooling performance.In winter,the system could recycle the waste heat from the driving motor effectively and reduce the load of the external heat exchanger.Therefore,the heating performance was improved compared with the air-source heat pump.The proposed model could simulate the performance of the dual-source heat pump,which could provide suggestions for the system design and optimization,and shorten the design cycle.