Implementation of a series resonant converter with series-parallel transformers

This study presents a series resonant converter with series-parallel transformers in order to achieve zero voltage switching (ZVS) turn-on of MOSFETs, zero current switching (ZCS) turn-off of rectifier diodes, less voltage stress of rectifier diodes, less secondary winding with a full-wave rectifier and load current sharing. Two series resonant modules with the same switches are operated with the phase-shifted half switching cycle. In each resonant converter, primary windings of two transformers are connected in parallel in order to share the input current and reduce the root-mean-square (rms) current on primary windings such that copper losses of the transformers are reduced. The secondary windings of two transformers are connected in series in order to ensure that the primary currents are balanced to share load current. Thus the sizes of the transformer core and bobbin are reduced. Two full-wave diode rectifiers are adopted on output side such that the voltage stress of rectifier diodes is clamped to output voltage, rather than being two times the output voltage as in a conventional centre-tapped rectifier topology. Laboratory experiments with a 1000-W prototype were provided to describe the effectiveness of the proposed converter.