Control method and system for refrigeration, oil return and noise reduction of multi-split air-conditioner

Abstract

A control method and system for refrigeration, oil return and noise reduction of a multi-split air-conditioner, wherein the method includes: when the accumulative time that the frequency of a compressor is smaller than the set frequency threshold reaches the oil return cycle and a standby indoor unit exists, conducting an oil return running mode; resetting the accumulative time; starting counting the oil return running time; calculating the indoor unit starting load; determining the opening degree of an expansion valve of the standby indoor unit according to the indoor unit starting load and whether there is anyone in a room where the standby indoor unit is located; controlling the compressor to run according to the set oil return frequency; and when the oil return running time reaches the oil return set time, exiting the oil return running mode, and conducting a normal refrigerating running mode.