A transformer assisted ZVS scheme for flyback converter

This paper presents a novel zero-voltage-switching (ZVS) scheme for flyback converter. The principle of operation of the converter is analyzed in detail. A comparatively small assisted transformer is in series with the main transformer. The ZVS conditions are achieved when the current across the magnetizing inductance of assisted transformer is bi-directional. By using hysteresis current control, ZVS conditions are ensured over wide load range. The magnetizing inductance current of main transformer is kept in continuous conduction mode (CCM) with small ripple, which overcomes the drawbacks of SRFC and has comparatively high efficiency. Prototype of the converter has been build to verify the proposed concept. The experimental results are presented and they verify the analysis