High-efficiency, high step-up DC-DC converters

Many applications call for high step-up dc-dc converters that do not require isolation. Some dc-dc converters can provide high step-up voltage gain, but with the penalty of either an extreme duty ratio or a large amount of circulating energy: DC-DC converters with coupled inductors can provide high voltage gain, but their efficiency is degraded by the losses associated with leakage inductors: Converters with active clamps recycle the leakage energy at the price of increasing topology complexity. A family of high-efficiency, high step-up dc-dc converters with simple topologies is proposed in this paper. The proposed converters, which use diodes and coupled windings instead of active switches to realize functions similar to those of active clamps, perform better than their active-clamp counterparts. High. efficiency is achieved because the leakage energy is recycled and the output rectifier reverse-recovery problem is alleviated.