Power conversion apparatus, motor drive apparatus, and refrigeration cycle application device

A power conversion apparatus comprising:

• a rectifying unit rectifying a power-supply voltage applied from an AC power supply;
• a capacitor connected to an output end of the rectifying unit;
• an inverter connected across the capacitor, the inverter converting DC power output from the capacitor into AC power and outputting the AC power to a device on which a motor is mounted;
• a first detecting unit detecting the power-supply voltage;
• and
• a control unit calculating a power-supply frequency that is a frequency of the power-supply voltage on a basis of a detection value by the first detecting unit, setting the power-supply frequency as a detection value of the power-supply frequency, and performing, on a basis of a set frequency set on a basis of the detection value of the power-supply frequency, pulsation compensation control of reducing a pulsatile component of a capacitor current that is a charge and discharge current of the capacitor, wherein
• in a case where an absolute value of a difference between the detection value of the power-supply frequency and the set frequency exceeds a threshold, the detection value of the power-supply frequency is updated as a new set frequency, and
• in a case where the absolute value of the difference between the detection value of the power-supply frequency and the set frequency does not exceed the threshold, a current set frequency is maintained.