To　support　higher　voltage　onboard　power　supply　system　and　electric　vehicle　(EV)　endurance　scheme,　reconfiguration　on　novel　unbalance　levels　strategy　is　developed　and　adopted　in　a　three-level　bidirectional　inductor-inductor-capacitor　(LLC)　resonant　converter　for　wider　voltage　charging　between　supercapacitor　energy　storage　(SCES)　and　battery　energy　storage　(BES)　in　hybrid　energy　storage　system　(HESS),　which　the　proposed　converter　is　composed　of　an　LLC　resonant　tank　module　(RTM)　and　two　three-level　coupling　cascaded　neutral　point　clamping　active　bridge　(3L-CCNPC).　Also,　the　definition　of　each　voltage　gain　mode　in　forward　and　backward　workings　is　established　by　hybrid　modulation　strategy　with　flexible　multilevel　output　ability　of　novel　active　bridge.　Besides,　a　wider　range　of　the　unified　bidirectional　voltage　gain　is　achieved　by　switching　among　multiple　voltage　gain　modes,　which　can　be　implemented　by　moving　among　unified　bidirectional　voltage　gain　points.　Based　on　the　optimization　objectives,　such　as　narrowing　the　pulse　frequency　modulation　(PFM)　variation　range,　the　parameters　of　LLC　RTM　are　designed.　Finally,　the　results　from　built　experimental　prototype　can　verify　that　the　obtained　voltage　gains　are　all　close　to　the　theoretical　design　values,　and　the　key　waveforms　visually　reflect　the　characteristics　of　novel　unbalance　levels　strategy　adopted　in　bidirectional　voltage　gain　modes　of　each　gain　point.　©　2015　IEEE.