A High Efficiency Boost Pre-regulator Merging with an Asymmetric LLC Standby Converter in DC Power Distribution System for Data Center

This paper proposes a new structure of the server power supply for DC power distribution system. The proposed structure consists of a boost converter for the pre-regulating stage and an asymmetric LLC (ALLC) converter for the standby stage. The switches of two converters are integrated to reduce the number of components. To regulate the output voltages of both stages tightly, a hybrid control of pulse width modulation (PWM) and pulse frequency modulation (PFM) is used. The proposed structure features zero-voltage-switching (ZVS) turn-on of switches resulting in a small switching loss. In addition, the snubber is not required in the proposed structure. As a result, higher efficiency than the conventional structure can be achieved. The feasibility of the proposed structure is confirmed with 260-380 $V_{DC}$ input, 400 $V_{DC}$ /500 W (boost converter), and 12 $V_{DC}$ / 25.2 W (ALLC converter) output prototype.