A New Soft-Switching Two-Switch Forward Converter

In this paper, a new soft-switching two-switch forward converter topology has been proposed. Compared with conventional two-switch forward converter, the proposed converter employs an auxiliary switch and a clamp capacitor to instead of two reset diodes, not only its duty cycle can exceed 0.5 to achieve wide range input voltage, but also soft switching can be achieved for all switches. Especially, voltage stress across main switches can be clamped at 1/2 V_in, voltage stress across auxiliary switch can be clamped at V_in. In addition, due to clamp capacitor series with the transformer, duty ratio can be extended with equation V_o=V_in(1-D)D/N. Therefore, as a kind of better cost-effective approach, it is very attractive for high input, wide range and high efficiency application.