Power factor correction method and apparatus and power supply using the same

摘要

A power factor compensation method and apparatus adapted for use in a power supply which provides direct-current (DC) power via a capacitive input type smoothing circuit, and an improved power supply using the same. The power factor compensation method can correct a power factor in the power supply which rectifies an input alternating-current (AC) voltage and smoothes the same using the capacitive input type smoothing circuit to supply a DC voltage. The method may include rectifying the input AC voltage, cutting off a pulsating current generated in the rectifying operation at phases of about pi/2 and 3 pi/2 of the input AC voltage so that the pulsating current is not transferred to a smoothing circuit, and smoothing the pulsating current generated in the cutting-off operation. The power factor compensation apparatus does not form a peak envelope of current at phases of about pi/2 and 3 pi/2 of the input AC voltage, thereby improving a power factor and reducing a harmonic current. The power factor compensation apparatus uses a leak inductance in an AC transformer at maximum to provide a low-price power supply.