Comparisons of zero-voltage-transition Cuk converters

With continuous input and output current, wide output voltage range and a small output filter, Cuk topology has received more and more attention in recent years. Soft switching is especially important to a Cik converter, because the power handling capability requirements of semiconductor devices are higher than those of other topologies. Several kinds of newly proposed zero-voltagetransition (ZVT) topologies can be applied to Cik converters to achieve soft switching. These ZVT topologies combine both the merits of conventional PWM converters and resonant converters. The power switches in the ZVT topologies commutate under zero-voltage-switchmg with the aid of resonant snubber cells during a short ZVT time. Circuit operations are identical to common PWM topologies during the rest time. Four classes of ZVT topologies for Cuk converters, with power MOSFETs employed as power switches, are discussed. Qualitative descriptions and experimental results are presented to illustrate each class of ZVT topology.