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

A power conversion apparatus, comprising:

• a converter rectifying a first AC voltage supplied from an AC source;
• a capacitor connected to an output end of the converter, the capacitor smoothing a first DC voltage rectified by the converter into a second DC voltage including a first ripple;
• an inverter connected across the capacitor, the inverter converting the second DC voltage into a second AC voltage corresponding to a desired frequency;
• a detection unit acquiring a physical quantity correlated with the second DC voltage, wherein the second AC voltage is controlled to superimpose a second ripple correlated with the first ripple on an output voltage of the inverter, and
• one or more pulsating component extraction units extracting at least one specific frequency component from the physical quantity detected by the detection unit, wherein pulsating component extraction units extracting the frequency component are changed depending on a period of a pulsating component of the extracted frequency component,
• wherein a frequency of the first ripple is a sum of a frequency component that is twice a fundamental frequency of the first AC voltage, and a frequency component that is a multiple of the fundamental frequency of the first AC voltage.