Control device, refrigerator, control method, and abnormality detection method

A control method for a refrigerator provided with a plurality of compressors connected in parallel, the control method comprising:

• acquiring values of currents flowing through electric motors that are configured to drive each of the plurality of compressors;
• calculating an operation point indicated by an air volume and a compression ratio of the plurality of compressors;
• detecting occurrence of surging or droplet suction, while distinguishing the surging from the droplet suction, on the basis of a deviation between a plurality of the values of currents and the operation point;
• performing a predetermined surging protection operation when the occurrence of the surging is detected;
• and
• maintaining a current operation state when the droplet suction is detected.

An abnormality detection method for a refrigerator provided with a plurality of compressors connected in parallel, the abnormality detection method comprising:

• acquiring values of currents flowing through electric motors that are configured to drive each of the plurality of compressors;
• calculating an operation point indicated by an air volume and a compression ratio of the plurality of compressors;
• and
• determining that surging, and not droplet suction, occurs in at least one of the plurality of compressors when a deviation between a plurality of the values of currents is equal to or larger than a predetermined threshold value and the operation point indicates that the air volume is smaller than a predetermined reference.

An abnormality detection method for a refrigerator provided with a plurality of compressors connected in parallel, the abnormality detection method comprising:

• acquiring values of currents flowing through electric motors that are configured to drive each of the plurality of compressors;
• calculating an operation point indicated by an air volume and a compression ratio of the plurality of compressors;
• and
• determining that droplet suction, not surging, occurs in at least one of the plurality of compressors when a deviation between a plurality of the values of currents is equal to or larger than a predetermined threshold value and the operation point indicates that the air volume is larger than a predetermined reference.