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

A power converter, comprising:

• a rectifier rectifying first AC power supplied from a commercial power source;
• a capacitor connected to an output end of the rectifier;
• an inverter connected across the capacitor, the inverter generating second AC power and outputting the second AC power to a motor;
• and
• processing circuitry controlling operation of the inverter such that pulsation according to a power state of the capacitor is superimposed on a drive pattern of the motor, to reduce a charging and discharging current of the capacitor, the power state of the capacitor including at least one of a rectified current flowing from the rectifier, an inverter input current flowing into the inverter, a capacitor current that is the charging and discharging current of the capacitor, and a capacitor voltage that is a voltage of the capacitor, wherein
• the processing circuitry performs load pulsation compensation control to reduce vibration of the motor and power pulsation compensation control to reduce the charging and discharging current of the capacitor while performing constant current load control to control a rotational speed of the motor, and generates a q-axis current margin that is the difference between a q-axis current limit value and a q-axis current command, and uses the q-axis current margin to generate a torque current command for the load pulsation compensation control such that a torque current command allocatable to the power pulsation compensation control remains.