Zero-voltage-transition topologies for Cuk converters

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