A High-Quality Rectifier Based on the Forward Topology with Secondary-Side Resonant Reset

The use of buck-derived topologies for unity power factor ac-to-dc applications is limited by their inherent inability to draw current from the line in those intervals, during the line half period, in which the input voltage is lower than the output one. This drawback is overcome in the proposed high-quality rectifier based on the forward topology with secondary-side resonant reset. The employed secondary side reset capacitor is able to provide proper transformer reset by recycling the transformer stored energy to the load and, at the same time, it allows to draw energy from the line even when the input voltage is lower than the output one. Consequently, besides to a better utilization of the transformer core (bipolar core excitation), a low distorted input current waveform can be obtained with a power factor close to unity. Experimental results of a 200 W prototype confirm the theoretical expectations.