A resonant converter device comprising a selectable primary winding comprising a plurality of circuit legs, the selectable primary winding comprising one or more of a tapped primary winding or a plurality of switchable primary windings. At least one secondary winding coupled to the selectable primary winding to form a resonant transformer. At least one resonant inductor coupled to at least one of the plurality of circuit legs. A plurality of resonant capacitors, each circuit leg comprising at least a respective one of the plurality of resonant capacitors, and at least a second resonant capacitor of the plurality of resonant capacitors coupled within the second circuit leg. And, one or more switching devices connected to the resonant transformer and configured to selectively vary a resonant impedance of the resonant converter device when a voltage inputted to the resonant converter device varies.