Implementation of a current-fed high step-up DC-DC converter

Based on SEPIC converter and cascade topology, a current-fed high step-up DC-DC converter is presented in this paper. The input inductor of the proposed converter is operated in continuous conduction mode (CCM), which has lower pulsating input current and thus reduced current ripple. A coupled inductor in the proposed circuit is employed to achieve higher voltage conversion ratio and avoid operation at extreme duty ratio via a proper turn ratio. The leakage inductance of the coupled inductor is designed to be recycled to output load. The voltage spike on the main switch can be clamped. Therefore, low power-rating and low on-resistance can be adopted to decrease both switching and conduction losses. Moreover, synchronous rectifier (SR) is applied at the front-end of the proposed converter to further decrease conduction losses. Feasibility and effectiveness of the proposed circuit are verified via computer simulations and practical experiments.