Tbis paper proposes a balf bridge LLC resonant converter witb bigb voltage gain employing Silicon Carbide (SiC) metal-oxide-semi-condctor field-effect transistor (MOSFET) for tbe DCIDC stage in tbe single-pbase AC/DC power system. Tbis converter is based on tbe switcb integration tecbniques, wbicb is merging tbe active-clamp forward (ACF) circuit and HB LLC resonant converter. Tbe primary conduction loss can be significantly reduced by tbe bigb voltage gain. Altbougb bigb voltage rating MOSFET is required, by applying bigb voltage rating SiC MOSFET witb low cbannel resistance, tbe proposed converter can sbow bigb performance. Moreover, to asymmetric pulse widtb modulation (APWM), tbe optimal design for bigb efficiency can be acbieved regardless tbe bold-up time and large ripple voltage. Tbe validity of tbe proposed converter is confirmed by tbe experimental results of a prototype converter witb 400VDC input and 800W (12V/6SA) output.