Design of high efficiency Boost-Forward-Flyback converters with high voltage gain

This paper proposed a novel dc-dc converter to achieve high step-up voltage gain without an extremely high duty ratio. The proposed converter controlled by only a single pulse width modulation (PWM) for the power switch. This thesis is a design of Boost-Forward-Flyback (BFF) converter with high voltage gain. The circuit structure is integrated by Boost, Forward and Flyback.The figuration of the proposed converter is a quadratic boost converter with the coupled inductor in the second boost converter. It combines coupled inductor to achieve high step-up voltage gain. The leakage inductance energy of the coupled inductor can be recycled to reduce the voltage stress and power losses. Therefore, low voltage rating and low conduction resistance switch can be selected to improve converter efficiency. To deserve, the coupled-inductor can be adjusted by increasing the turn ratios of the secondary-side winding to achieve higher voltage gain feature. The operating principles, theoretical analysis, experimental waveforms and efficiency curves are presented.