Interleaved Half-Bridge Flyback Converter With Zero-Current Switching

Conventional interleaved half-bridge flyback converters can recycle the leakage energy stored in leakage inductance to clamp the voltage across the main power switches at a dc input voltage. However, such converters still suffer from high switching losses, especially turn-OFF losses. In this paper, a novel turn-OFF zero-current-transition (ZCT) circuit is proposed for reducing the turn-OFF switching losses. The proposed ZCT interleaved halfbridge flyback converter operates at a fixed frequency without increasing the voltage stresses of the main switches. To verify the design, a laboratory prototype is implemented with 100 kHz, an input voltage of 400 V, and an output voltage of 24 V/480 W. The experimental results reveal that the proposed converter at full load and 20% load has efficiencies of 93.05% and 89.06%, yielding efficiency improvements of 1.17% and 4.12%, respectively, compared with the conventional interleaved half-bridge flyback converter.