Active-clamping ZVS flyback converter employing two transformers

This paper presents a two-transformer activeclamping zero-voltage-switching (ZVS) flyback converter, which is mainly composed of two active-clamping flyback converters. By utilizing two separate transformers, the proposed converter allows a low-profile design to be readily implemented while retaining the merits of a conventional single-transformer topology. The presented two.transformer active-clamping ZVS flyback converter can approximately share the total load current between two secondaries. Therefore, the transformer copper loss and the rectifier diode conduction loss can be decreased. Detailed analysis and design of this new two-transformer active-clamping ZVS flyback converter are described. Experimental results are recorded for a prototype converter with an ac input voltage ranging from 85 to 135 V, an output voltage of 24 V and an output current of 8 A, operating at a switching frequency of 180 kHz. Index Terms--Active clamping, flyback, low-profile design, zerovoltage-switching (ZVS).