Motor driving device, and heat pump device and refrigerating and air conditioning device using the motor driving device

A motor driving device for driving a motor comprising:

• an inverter to convert a direct-current voltage into an alternating-current voltage and apply the alternating-current voltage to the motor, the inverter being used for driving motor;
• and
• a direct-current-voltage detector to detect the direct-current voltage;
• a current detector to detect an electric current flowing to the inverter;
• and
• an inverter controller to receive value of the voltage detected by the direct-current voltage detector and a value of the electric current detected by the current detector, and output PWM signals for driving switching elements of the inverter, wherein
• a phase difference between a phase of a carrier signal used for generation of the PWM signals and a phase of the alternate-current voltage is set to a value that is not an integer multiple of 60°, and
• a frequency of the PWM signal is synchronized with a frequency of the alternating-current voltage, the frequency of the PWM signal being an integer multiple of three times the frequency of the alternating-current voltage.