Analysis, design and implementation of a new zerovoltage- switching interleaved asymmetrical halfbridge converter using an integrated transformer

This study proposes an interleaved asymmetrical half-bridge zero-voltage-switching (ZVS) forward-flyback converter (AHBFFC), which uses a single magnetic core. The presented topology is composed of an asymmetrical half-bridge forward converter in parallel with an asymmetrical half-bridge flyback converter. The two converters, which are paralleled in AHBFFC use common switches with ZVS operation. Moreover, two switches of the converter have low-voltage stresses in comparison with the switches used in active-clamping converters. The interleaved operation of the converter reduces the input and output current ripples and hence the size of the output choke and capacitor. The transformer copper loss is decreased because of sharing the input and output currents between two transformers. In this topology, the two transformers are integrated into one magnetic core including gapped legs. Owing to the coupling between two transformers, input current ripple and crossing area of the magnetic core are reduced. The proposed converter has some advantages like high-efficiency, high-power density, small size and simple control. A prototype converter has been implemented and experimental results have been recorded with an ac input voltage of 85-135 Vrms, an output voltage 12 V and output current 15 A.