In this paper, a third winding and an additional switched capacitor are inserted into each phase of the conventional interleaved Flyback converter to derive a novel triple boost converter for high step-up conversion. Furthermore, the active clamp circuit, which is composed of a power MOSFET and a small capacitor, is inserted to the primary side of each phase to recycle the leakage energy and to suppress the switch turn-off voltage spikes. Moreover, ZVT soft switching performance is achieved to reduce the switching losses for all the primary power switches during the whole switching transition. In addition, the leakage energy is recycled and the secondary side diode reverse-recovery problem is alleviated. Finally, a 500W 24V-380V prototype is built and tested to verify the effectiveness of the proposed solution.