High step-up soft-switched dual-boost coupled-inductor-based converter integrating multipurpose coupled inductors with capacitor-diode stages

A soft-switched dual-boost coupled-inductor-based converter is proposed which possesses an intrinsic advantage, in terms of transferring the energy directly to output to provide the essential voltage and power for load. The fabulous characteristic of the proposed structure, the combination of forward and flyback converter, makes it possible to utilise one magnetic core for two coupled inductors, advancing the power density. Another implication of proposed converter is the fact that leakage inductances pave the way for the zero-current-switching implementation by confining the diodes current slope during turn-off period. As regards the voltage conversion ratio, the secondary windings of the coupled inductors operate in series with the capacitors of both voltage-doubler stage and capacitor-diode stages; consequently, designer is under no obligation to use coupled inductors with extreme turn ratio. Concerning the mentioned features of converter besides its high-efficiency power conversion over a broad range of input voltage, the proposed structure is well suited for the purpose of high step-up dc-dc converter. Lastly, the results of laboratory prototype, working with switching frequency of 50 kHz and output voltage 380 V, are convincingly in line with the mathematical analysis.