Research on efficient defrosting control logic for transcritical CO₂ electric vehicle heat pump air-conditioning system

The improper defrosting operation would not only cause severe performance deterioration and energy waste but also reduce comfort. The dynamic control strategy of electric vehicle heat pumps is more complicated than that of other heat pumps. To find an efficient defrosting control logic, a transcritical CO₂ heat pump test bench for electric vehicles was built. First, the thermodynamic dynamic characteristics in the defrosting process were analyzed, based on which a method for accurately determining the end of defrosting was proposed. Then, a comparative experiment on the core parameters that affected the defrosting speed was carried out, and suggestions for optimizing defrosting control strategy were given. In addition, the dynamic thermodynamic characteristics in the continuous frost-defrosting process under different humidity were further studied. It was found that the humidity decided whether additional dehumidification strategies should be adopted after defrosting. Finally, detailed dynamic control logic of the operation process from heating and frosting to defrosting was proposed. The research will promote the development of the electric vehicle industry by improving defrosting efficiency and meeting the requirements of socially sustainable development through saving energy.