IGBT with Refrigeration Compressors

Refrigerators have become essential appliances in society for the preservation of food and beverages. The quality of life for people has been greatly enhanced with the availability of affordable refrigerators for homes. Most household refrigerators utilize the vapor compression cycle with a circulating refrigerant used to cool the refrigerator compartment. Household refrigerators originally used an on/off controlled, constant-speed, single-phase induction motor to drive the compressor. The poor efficiency of this approach made the refrigerator one of the highest power consumption appliances in the home. In order to improve the efficiency, modern refrigerators with the Energy star rating utilize variable-speed, three-phase induction motor drives. Current models that are Energy Star qualified use 50 percent less energy than the average models made in 1974.

The variable speed drive to the induction motor is provided using the six IGBTs in the inverter stage. The author’s state: “The total energy savings was about 40%. The system is very quiet and maintains a constant temperature within 0.1 degree Celsius which improves the quality and shelf life of food stored in the refrigerator.” Many companies have optimized IGBTs for use in refrigerator compressor drives due to the large market opportunity. Some companies have developed intelligent power modules, which combine the IGBTs, fly-back rectifiers, and the drive circuits into a single module. This provides a very compact and low cost motor drive option that can be easily adopted for the manufacturing of refrigerators.