Single-stage single-switch power factor correction AC/DC converter

A single-stage single-switch power factor correction AC/DC converter is proposed in which the power factor correction (PFC) inductor is connected to a tap on the primary winding of the DC/DC flyback converter stage; there is direct energy transfer of a part of the input energy to the output and the DC-bus voltage feedback. The additional discharge path in the PFC inductor and DC-bus voltage feedback effectively suppresses the DC-bus voltage and increases the overall efficiency. Experimental results for a 60 W converter at a constant switching frequency of 70 kHz are obtained to show the performance of the proposed converter. It is shown that the voltage across the DC-bus capacitor can be held below 405 V even though the converter operates in a wide range of input voltages (90∼265 V AC) and the measured input current harmonics satisfy the IEC 61000-3-2 Class D requirements.