A Control Scheme for an AC-DC Single-Stage Buck PFC Converter with Less Harmonics

In this paper a control scheme for an ac-dc single-stage buck PFC converter with less harmonics is implemented. By providing extra parameters like an auxiliary switch and two diodes, in the conventional buck PFC converter the dead zones in ac input current of can be vanished. An improved fixed ON-time control is implemented and employed in this proposed buck PFC converter to force it that works in critical conduction mode (CRM) of operation. With finest proper regulating parameters, approximately unity power factor can be attained and the harmonics of the input current can meet the IEC61000-3-2 class C standard within the worldwide input voltage assortment. Furthermore, the reliability of the designed converter is not declined compared to the traditional buck converter. A 10W laboratory prototype of the Buck power factor correction converter with 12V input voltage was setup using PIC 16F877 microcontroller. Compared to conventional power factor correction converters, the power factor was improved greatly with the proposed topology. This proposed topology is very suitable for high-power non isolated LED drivers with high power factor requirements.