New zero-current-transition PWM DC/DC converters without current stress

In this paper, novel zero-current-transition (ZCT) PWM DC/DC converters without additional current stress and conduction loss on the main switch are presented during the resonance period of the auxiliary cell. The auxiliary cell consists of a resonant inductor, a resonant capacitor, an auxiliary switch and an auxiliary diode in parallel with the main switch and the zero-current-switching (ZCS) range of the main and the auxiliary switch of the proposed converters are entirely achieved by operating the auxiliary cell. Also the reduced di/dt, which is obtained by a resonant inductor, helps soft turn-on of the main switch. The theoretical analysis and the operation principle of the new ZCT technique are described in detail with a boost converter as an example. The simulation and the experiment were performed under 1 kW output power, 100 kHz switching frequency with a boost converter and 1 kW output power, 50 kHz switching frequency with a full-bridge (FB) converter to verify the validity of the proposed ZCT technique.