A novel technique to achieve unity power factor and high quality waveform in AC-to-DC converters

This paper presents a novel power factor correction technique for boost type AC-to-DC power converters in continuous conduction mode. Instead of using the inductor current or switching device current, in this paper, the diode current in the boost converter is used to formulate the duty ratio of the switch in a special way which makes the input current sinusoidal and in phase with the input voltage. To improve the dynamic performance and minimize the input current harmonic components, a new double-injection compensation method is employed in the voltage feedback loop. This power factor corrector has the following advantages: (1) operation with constant switching frequency; (2) elimination of input voltage sensing, the error amplifier in the current loop and the multiplier in output voltage feedback loop; (3) minimal total harmonic distortions in the input current; (4) fast dynamic response in the voltage loop; (5) simple implementation of the control circuit; and (6) smaller output filter capacitor. The principle of operation is explained. Experimental results are presented to verify the feasibility of the control strategy.