Active-clamp DC/DC converters using magnetic switches

Although DC/DC power converters with coupled inductors can provide high voltage gain to meet the requirements of many emerging applications, their efficiency is degraded by losses associated with the leakage inductors. The active-clamp technique recycles the leakage energy, but at the price of increasing topology complexity. A family of high-efficiency, high step-up DC/DC power converters is proposed in this paper. The proposed converters, which use diodes and coupled windings instead of active switches to realize clamp functions, present better performance than their active-clamp counterparts. The efficiency of a 35 W front-end converter for a high intensity discharge lamp ballast is higher than 90% with 12 V input and 100 V output. The high efficiency is achieved because the leakage energy is recycled and the switch voltage stress is minimized.