Buck-Type Single-Switch Integrated PFC Converter With Low Total Harmonic Distortion

Abstract

Conventional buck power factor correction (PFC) converter has the disadvantage of high harmonic currents, which limits its applications. In this article, a buck type single-switch integrated PFC converter is presented and analyzed. It is composed of buck and flyback PFC converters by using only one active switch, which benefits from simple control. The buck and flyback PFC converters are input-parallel and output-parallel connected. With critical conduction mode constant on time control, the effect of dead zone of buck input current is eliminated by flyback unit. Therefore, the input harmonic currents of the proposed converters can easily meet IEC61000-3-2 Class C limits. With the advantages of buck and flyback PFC converters, the proposed converter can achieve high efficiency and low total harmonic distortion in universal-input applications. Simplified steady-state analysis and design considerations are introduced in this article. Finally, a 96-W prototype with 94.5% peak efficiency is built to verify the analysis results.