Pre-Regulating Boost Converter with Asymmetric Half-bridge LLC Converter for DC Server Power Supply

This paper proposed an boost pre-regulating converter with an asymmetric half-bridge double-ended LLC converter for DC server power supply. Proposed converter consists of boost converter for pre-regulating stage and LLC converter for stand-by stage. Due to the integration of the switches, the switch for stand-by stage can be eliminated. Two output voltages, main output voltage and stand-by output voltage, are regulated by using both pulse width modulation and pulse frequency modulation controls. The switches in the proposed structure achieve zero-voltage-switching (ZVS) in the nominal state. As a result, the proposed structure that contains boost pre-regulating converter and LLC stand-by converter has higher efficiency than the conventional structure which has flyback stand-by converter. The feasibility of the proposed structure is confirmed with 260-380V input and 400V/500W main output, 12V/25.2W stand-by output prototype.