Comparison of Three Front-end DC-DC Converters for 1200W Server Power Supply

Server power supply with universal input is composed of power factor correction (PFC) stage and front-end dc-dc stage. The output voltage of PFC stage varies with input voltage rms in order to improve the efficiency at low line. So it is important to select a dc-dc converter with wide input range. This paper proposes that a hybrid full-bridge three-level (HFB TL) converter is suitable for this application. The merits of this converter are low voltage stress of power semiconductor, small circulating energy and output filter inductor. The features of proposed converter are compared with the conventional phase-shift full-bridge (PS FB) dc-dc converter. The prototypes of two PS FB converters with different input range and HFB TL converter are built up to verify the analysis