Flash tank-based control of refrigerant injection into a compressor

A method of controlling injection into a compressor in a refrigeration cycle, wherein the method is performed in a refrigeration cycle, which comprises at least a flash tank configured for receiving a refrigerant and separating liquid refrigerant and vapour refrigerant, and a compressor configured for compressing the refrigerant, wherein the compressor comprises a means for compressing, a suction port and an injection port, which is connected to the means for compressing for at least a time instance of the refrigeration cycle, wherein the flash tank is connected to the injection port of the compressor via an injection valve,

• the method comprising:
• determining, via a sensor, a pressure in the flash tank;
• controlling, via a controller, the injection valve based on the determined pressure in the flash tank;
• and
• controlling, via the controller, the compressor based on the determined pressure in the flash tank, wherein controlling the compressor comprises if the determined flash tank pressure is lower than a threshold, determining, by the controller, an operating speed for the compressor and setting the operating speed to the determined operating speed,
• wherein the threshold is referred to as a first threshold and wherein controlling the compressor comprises:
• if the controller determines that the flash tank pressure is equal to or greater than the first threshold and lower than a second threshold, unloading the compressor;
• and
• if the controller determines that the flash tank pressure is greater than the second threshold, stopping operation of the compressor via the controller.