Quasi‐active power factor correction on flyback‐based dc/dc converter

This paper presents a novel input current shaper based on a quasi‐active power factor correction (PFC) scheme. In this method, high power factor and low harmonic content are achieved by providing an auxiliary PFC circuit with a driving voltage which is derived from a third winding of the transformer of a cascaded dc/dc flyback converter. It eliminates the use of active switch and control circuit for PFC. The auxiliary winding provides a controlled voltage‐boost function for bulk capacitor without inducing a dead angle in the line current. Since the dc/dc converter operates at high switching frequency, the driving voltage is also of high switching frequency, which results in reducing the size of the magnetic components. Operating principles, analysis and experimental results of the proposed method are presented.