Refrigeration system with parallel compressors

A control system for a refrigeration system, the control system comprising:

• a three-way valve, an inlet of the three-way valve configured to fluidly couple with an outlet of a first compressor, the first compressor configured to receive return refrigerant from a heat exchanger, wherein the three-way valve is transitionable between a first position in which the three-way valve provides the refrigerant provided by the first compressor to a second compressor, and a second position in which the three-way valve provides the refrigerant provided by the first compressor to a third compressor, the second compressor and third compressor arranged in parallel;
• a temperature sensor configured to measure a temperature indicating a degree of superheat of the refrigerant before entering the second compressor;
• and
• a controller configured to:
• obtain the temperature from the temperature sensor;
• determine a duty cycle based on the temperature, the duty cycle defining a first portion of a time period for the three-way valve to be in the first position and a second portion of the time period for the three-way valve to be in the second position;
• and
• operate the three-way valve to transition between the first position and the second position according to the duty cycle.

A method for controlling a three-way valve that selectively diverts return refrigerant from a first compressor to a second compressor or a third compressor, the second and third compressor in parallel, the method comprising:

• obtaining a temperature of refrigerant entering the second compressor or the third compressor, the temperature indicating a degree of superheat of the refrigerant;
• determining a duty cycle based on the temperature, the duty cycle comprising a first portion of a time period for the three-way valve to divert return refrigerant to the second compressor in a first position and a second portion of the time period for the three-way to divert the return refrigerant to the third compressor in a second position;
• determining, based on the duty cycle, if the three-way valve should be transitioned into the first position, transitioned into the second position, or maintained in a current one of the first position or the second position;
• and
• transitioning the three-way valve into the first position or the second position, or maintaining the three-way valve in the first position or the second position;
• wherein in the first position, the first compressor provides the return refrigerant to the second compressor through the three-way valve;
• and
• wherein in the second position, the first compressor provides the return refrigerant to the third compressor through the three-way valve.