The hysteresis or overshoot in a variable refrigerant flow (VRF) system control is studied. This study considers a variable-frequency rolling rotor refrigeration system as the research object. By changing the compressor frequency and opening of the electronic expansion valve

a curve fitting model under a separate control of the two processes was established. An experimental research on the synchronous control method of the two processes under different working conditions was carried out. The results show that the superheat decreased with the opening of the electronic expansion valve. When the electronic expansion valve opening was 28%–32% and the frequency was 44.5–46.5 Hz

the degree of superheat control became more difficult. This condition could be improved by adjusting the temperature of the chilled water. Under certain conditions

the relationship between the frequency and opening of the electronic expansion valve could be obtained by controlling the mass flow. Synchronous control of the opening degree of the electronic expansion valve and compressor frequency was achieved; thus

the system could quickly reach a stable state.