Non-cascading structure based Flyback-Forward converter with large duty ratio

In this paper, a Flyback-Forward converter employing a non-cascading scheme is presented in discontinuous conduction mode. The converter is designed to enhance the duty ratio of over 50%. As a result, the flyback sub-converter acts in boost mode and generates stepped-up output voltage. Since the switch utilization is required to be as high as possible in a forward converter, in present case, this objective is also simultaneously achieved. The simulation results obtained for a 24 V, 24W converter show the duty ratio greater than 50%.