A METHOD FOR CONTROLLING SUCTION PRESSURE OF A VAPOUR COMPRESSION SYSTEM

A method for controlling a vapour compression system (1) is disclosed. The vapour compression system (1) comprises an ejector (4), and has a non-return valve (11) arranged in the refrigerant path between an outlet (12) of an evaporator (7) and an inlet (10) of a compressor unit (2), in such a manner that a refrigerant flow from the outlet (12) of the evaporator (7) towards the inlet (10) of the compressor unit (2) is allowed, while a fluid flow from the inlet (10) of the compressor unit (2) towards the outlet (12) of the evaporator (7) is prevented. A pressure, P0, of refrigerant leaving the evaporator (7) is measured and a value being representative for a pressure, Psuc, of refrigerant entering the compressor unit (2) is obtained. The pressures, P0 and Psuc, are compared to respective reference pressure values, P0,ref and Psuc,ref. In the case that ε0>εsuc, where ε0=P0-P0,ref and εsuc=Psuc-Psuc,ref, the compressor unit (2) is controlled based on P0, and in the case that εsuc>ε0, the compressor unit (2) is controlled based on Psuc.