Multi-split air conditioner and control method thereof

A multi-split air conditioner, wherein the multi-split air conditioner comprises a plurality of outdoor heat exchangers connected in parallel to a refrigerant main circulation passage, wherein a parallel branch in which each of the plurality of outdoor heat exchangers is located is provided with a branch control valve capable of controlling a flow rate of refrigerant flowing through the parallel branch;

• and an air supplement pipe assembly used for conveying a part of refrigerant in the refrigerant main circulation passage to an air supplement port of a compressor to supplement air to the compressor, wherein the air supplement pipe assembly comprises an air supplement pipeline, an air supplement heat exchanger and an air supplement control valve, two ends of the air supplement pipeline are respectively connected to the refrigerant main circulation passage and the air supplement port of the compressor, two heat exchange chambers of the air supplement heat exchanger are respectively connected in series to the refrigerant main circulation passage and the air supplement pipeline, and the air supplement control valve is used for controlling the flow rate of the refrigerant supplementing the air to the compressor;
• and the multi-split air conditioner further comprises a controller, used for:
• determining a current superheat degree of the multi-split air conditioner;
• when the current superheat degree of the multi-split air conditioner deviates from a set target superheat degree, controlling and regulating the flow rate of the refrigerant flowing through one or more of the branch control valves, so that the current superheat degree reaches the set target superheat degree;
• and
• controlling and regulating the flow rate of the refrigerant flowing through the air supplement control valve according to the flow rate of the refrigerant flowing through each of branch control valves.