Design criteria for resonant tank of LLC DC-DC resonant converter

This paper presents the design criteria for the resonant tank of the LLC resonant DC-DC converter. In order to have high efficiency within wide input voltage range, high power factor for the LLC resonant tank should be ensured. The inductance ratio of the series and parallel resonant inductors is designed according to the voltage gain and input power factor of the LLC resonant tank. Finally, the prototype circuit of the full-bridge LLC resonant converter with 48V output voltage at 12A output current is built to verify the proposed design criteria for the resonant tank.