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

This paper presents novel zero-current-transition (ZCT) PWM DC/DC converters without additional current stress and conduction loss on the main switch 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) ranges of the main and the auxiliary switch of the proposed converters are entirely achieved by operating the auxiliary cell. In addition, the resonant inductor of the proposed ZCT cell helps soft turn-on of the main switch. The theoretical analysis and the operation principle of the new ZCT technique are described in detail using a boost converter as an example. To verify the validity of the proposed ZCT technique, the simulation and the experiment were performed on the nonisolated and the isolated converter, respectively. Here, the nonisolated converter is a boost converter having 100 kHz switching frequency, 1 kW rating power, and the isolated converter is a full-bridge (FB) converter having 50 kHz switching frequency, 1 kW rating power.