Multi-split heat pump air conditioning system and control method thereof

Disclosed is a multi-split heat pump air conditioning system. An electromagnetic valve is arranged between an exhaust pipe and an air sucking pipe of a compressor of the multi-split heat pump air conditioning system, a high-pressure sensor is connected onto the exhaust pipe, and a low-pressure sensor is connected onto the air sucking pipe. A control method of the multi-split heat pump air conditioning system includes that when the air conditioning system receives a halt signal, the electromagnetic valve is energized before the compressor is closed, when detected difference between exhaust pressure and air sucking pressure of the system is lower than a specified value, the compressor is closed at first, and then the electromagnetic valve is closed; and when the air conditioning system works, the electromagnetic valve is energized if detected air sucking pressure of the system is lower than the minimum pressure value P1 for reliable running of the compressor. The multi-split heat pump air conditioning system and the control method have the advantages that the vortex compressor can be effectively prevented from reversely rotating at a halting instant of an outdoor unit, high electric potential is prevented from being generated instantaneously to impact electronic control elements of the system, air sucking pressure of the compressor can be increased when the air sucking pressure of the system is over low, problems that exhaust temperature and oil temperature rise, efficiency is reduced and the like of the system are prevented, reliability of the compressor is improved, and the service life of the compressor is prolonged.