Patent ID: 7450407
Filing Date: 2008-11-11
Classification: H02M

Abstract:
1. A control method for an AC/DC power converter, comprising the steps of: employing a voltage-regulation circuit to detect an output DC voltage from the AC/DC power converter applied to a power factor corrector, and employing the detected output DC voltage to produce a control signal; employing a current-detecting circuit to detect an input AC current from the AC/DC power converter; employing a multiplier circuit to multiply the control signal of the voltage-regulation circuit and the input AC current of the current-detecting circuit to produce a modulation signal; and employing a pulse-width-modulation/driving circuit that includes a third predetermined value and a third subtracter, a pulse-width-modulation circuit and a driving circuit and selects a high-frequency carrier wave to modulate the modulation signal of the multiplier circuit to produce a driving signal for the AC/DC power converter, with the third predetermined value being set for a peak value of the high-frequency carrier wave and the driving signal being used to drive the AC/DC power converter to obtain a voltage which is proportional to the input AC current so that the AC/DC power converter can act as a virtual resistor; wherein the acted virtual resistor is connected with an AC power system so that harmonic suppression and power factor improvement can be achieved, and a frequency of the input AC current can be synchronously changed in response to changes in frequency of voltages of the AC power source so that the AC/DC power converter can be normally operated under the AC power source with a frequency variation.