Control device

A control device comprising

• a processor configured to control operation of an inverter by a synchronous pulse width modulation control using a pulse width modulation signal, the inverter being coupled to a motor, and the pulse width modulation signal being generated by comparison of a carrier signal and a voltage command, wherein:
• the processor is configured to:
• when a motor speed of the motor is outside of a predetermined speed range, set a number of pulses of the carrier signal in one cycle of the voltage command to a main number of pulses;
• and
• when the motor speed is in the predetermined speed range, set the number of pulses of the carrier signal in one cycle of the voltage command to a sub number of pulses which is an odd number and smaller than the main number of pulses,
• the predetermined speed range is a speed range of the motor in which i) a harmonic component having a predetermined frequency band is generated when the motor is driven by the inverter under the synchronous pulse width modulation control with the number of pulses of the carrier signal in one cycle of the voltage command is the main number of pulses and ii) the harmonic component having the predetermined frequency band is not generated when the motor is driven by the inverter under the synchronous pulse width modulation control with the number of pulses of the carrier signal in one cycle of the voltage command is the sub number of pulses, and
• the predetermined frequency band is a frequency band in which resonance of a circuit including the inverter occurs due to the harmonic component having the predetermined frequency band.