A High Efficiency Boost Preregulator Merging With an Asymmetric LLC Standby Converter in DC Power Distribution System for Data Center

This article proposes a new structure of the server power supply for the dc power distribution system. The proposed structure consists of a boost converter for the preregulating 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 pulsewidth 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
$V_{\text{dc}}$
input, 400
$V_{\text{dc}}$
/500 W (boost converter), and 12
$V_{\text{dc}}$
/ 25.2 W (
ALLC
converter) output prototype.