High Light-Load Efficiency Power Conversion Scheme Using Integrated Bidirectional Buck Converter for Paralleled Server Power Supplies

Abstract

This paper proposes a new power conversion scheme for paralleled server power supplies. The snubber capacitor voltage is utilized for the secondary voltage source, from which bidirectional buck converter provides output power to the load under a very light-load condition. To increase the energy of the secondary voltage source, an additional voltage bus is connected between the snubber capacitors from each power supply. The main advantage of the proposed scheme is that high efficiency can be achieved especially under a very light-load condition because of the lowswitching and core loss achieved by using the buck converter instead of the conventional structure composed of a primary inverter, an isolation transformer, and a secondary rectifier. Furthermore, the buck converter is integrated into the secondary rectifier circuits, so additional components are minimized. The validity of the proposed converter is confirmed by the experimental results from two 12-V/750-W prototype modules.