Patent ID: 7049774

Claim:
An apparatus, comprising: a reactor which passes a specific frequency among an input AC power; a rectifier which converts the input AC power to a DC power; an inverter which inverts the DC power to an AC power to control a drive of a load; an input current detector which detects an input current of the input AC power; a zero crossing detector which detects a zero crossing point of the input AC power; a DC link voltage detector which detects a rectified DC voltage of the DC power; a power factor compensator which compensates a power factor of the power passing through the reactor; and a microcomputer which receives data detected by the input current detector, the zero crossing detector, and the DC link voltage detector, the microcomputer turning on the power factor compensator when a delay time, counting from the zero crossing time point, passes, the microcomputer turning off the power factor compensator when the input current of the input AC power detected by the input current detector reaches a first peak value, the microcomputer adjusting the delay time if the rectified DC voltage detected by the DC link voltage detector when the microcomputer turns off the power factor compensator is higher or lower than a target voltage.