Refrigerating and air-conditioning apparatus

A refrigerating and air-conditioning apparatus comprising:

• a refrigerant circuit in which a compressor having a built-in motor, a first heat exchanger, an expansion device, a second heat exchanger, and a four-way valve are connected to each other by pipes to allow refrigerant to circulate through the refrigerant circuit;
• a temperature sensor configured to measure a temperature of the compressor;
• an inverter configured to control the motor, and
• a heat generation control unit being provided in the inverter and configured to
• increase a temperature of the compressor when the heat generation control unit detects a decrease in a value measured by the temperature sensor during a defrosting operation performed on the first heat exchanger, and
• use a value of an excitation-current command for the motor as a controlled variable, and generate a negative excitation-current command.