An AC-DC converter with low input distortion and near unity power factor

A single-stage flyback converter is operated as a single-phase AC-DC converter with active power factor correction. The input filter required to reduce the differential mode conducted emissions is examined, and modulation of the switching frequency is suggested as a means of minimising the filter requirements. Various modulation strategies are studied and a simple analogue circuit implementation is presented for the optimum strategy. The influence of component tolerances on harmonic distortion is also investigated.<
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