A high step-up current fed multi-resonant converter with coupled inductor

The two input filter inductors of the previously proposed current fed multi-resonant converter (CFMRC) occupy too much volume and hence restrict the power density of the converter. In this paper, an integrated magnetic structure is adopted to the CFMRC´s input inductors to cut down the size, cost and loss of the CFMRC. With proper design, the inverse coupling of input inductors apparently reduces the ripple of the current flowing through the inductors. Thereby, the inductance can be reduced to further decrease the core size and copper length, and hence farther improve the power density as well as the efficiency of the converter. The above mentioned merits are verified by a 150 W prototype with integrated input inductors operating at 255 kHz switching frequency, the volume of the input inductors is reduced from 25410 mm³ to 7056 mm³ after integrating, and the full load efficiency is increased from 95.4% to 95.9%.