High Power Factor AC/DC Converter with High Step-Down Conversion Ratio

This paper presents high step-down AC/DC converter with discontinuous conduction mode (DCM) to achieve power factor correction, low harmonic AC current and output voltage regulation. Buck-boost type topology is adopted to reduce the DC bus voltage stress and achieve a high voltage step-down conversion ratio between the output and input sides. Since the input inductor is operated in DCM mode, the input line current can automatically follow the line voltage and the line current is a sinusoidal waveform with a DC offset and in phase with AC mains. Compared to a conventional buck converter, the proposed converter has wide duty ratio such that the conduction loss on power switches can be reduced. Finally, the experimental results based on a 200W prototype are provided to verify the effectiveness of the proposed converter. Copyright (C) 2011 Praise Worthy Prize S.r.L - All rights reserved