PROJECT TITLE :

Wide ZVS Range Asymmetric Half-Bridge Converter With Clamp Switch and Diode for High Conversion Efficiency

ABSTRACT:

A conventional asymmetrical 0.5-bridge (AHB) converter is widely used for dc-dc stage in low-to-medium power system. But, since the uneven operation of AHB converter causes the low efficiency over entire load condition, the conventional AHB converter is not typically considered for the candidate of server power system. In order to overcome the issues of the traditional AHB converter, a large zero-voltage-switching (ZVS) range AHB converter with a clamp switch and a clamp diode is proposed during this paper. The proposed AHB converter (PAHBC) replaces a low-aspect clamp diode with a MOSFET switch and adds an auxiliary winding, which changes the transformer turns-ratio. From these modifications and therefore the pulsewidth-modulation (PWM) control of clamp switch, the PAHBC can be designed optimally at nominal input condition and obtains additional dc gain at hold-up time condition. These advantages achieve the high conversion potency over the whole load condition. The operational principle and analysis of the PAHBC are presented in this paper and verified by a 340-four hundred V input and fifty V/500 W output laboratory prototype.