An interleaved series input RCD reset forward converter for wide voltage range application

An interleaved series input RCD reset forward converter for wide voltage range application is proposed in this paper. The converter is composed of two RCD reset forward cells. The two cells are connected in series with an interleaved manner. The duty cycle of each forward cell can be more than 50%, as a result, the effective duty cycle of the two cells can be more than 100%, which makes the proposed converter suitable for wide voltage range application. Compared to the conventional RCD reset single switch forward converter, the proposed converter maintains the merits that duty ratio can exceed 50%, while low voltage stress on main switches and high efficiency are obtained because only part of the magnetizing power is dissipated by the reset resistor. The voltage across the reset capacitor is low. In addition, the interleaved operation can reduce the current ripple in output filter. The topology, operation principle, characteristics and design consideration are analyzed in detail. A prototype of 70~130V input, 8V/25A output is built and the experimental results are presented to verify the analysis.