A　three-level　(TL)　LLC　resonant　converter　of　dual-bridge　(DB)　with　hybrid　control　modulation　strategy　is　proposed　for　the　wide　output-voltage　range　and　high　input-voltage　applications.　The　topology　integrates　two　neutral-point-clamped　arms　(NPCs)　through　an　auxiliary　transformer,　which　forms　a　new　controllable　double-voltage　structure　and　makes　all　MOSFETs　hold　half　of　the　input　voltage.　Based　on　the　characteristics　of　the　new　topology,　a　hybrid　modulation　strategy　is　proposed　corresponding　to　three　gain　modes,　which　include　conventional　pulse　frequency　modulation　(PFM)　and　fixed　frequency　phase　shift　modulation　(FF-PSM).　Compared　to　conventional　modulation　strategies,　the　proposed　hybrid　modulation　strategy,　which　improves　the　output　voltage　gain　range,　achieves　zero-voltage　switching　(ZVS)　of　all　the　MOSFETs　and　zero-current　switching　(ZCS)　of　rectifier　diodes　under　wider　operating　voltage　and　full　load　range.　To　minimize　the　frequency　window　and　improve　the　efficiency　of　the　converter,　the　parameter　optimization　method　is　designed,　which　based　on　the　characteristics　of　the　modulation　strategy　and　the　relationship　among　the　maximum　output　voltage　gain,　resonant　current　and　turned-off　current.　At　last,　the　experimental　results　of　the　600W　prototype　are　presented　to　confirm　the　theoretical　and　characterization　analysis.　IEEE