For　the　popularization　of　constant-current　charging　methods　for　energy　storage　batteries,　aiming　at　the　problem　that　the　conventional　voltage　source　direct　current　(DC)　converter　hasn’t　natural　constant-current　output　in　the　bidirectional　on-board　charger,　a　novel　bidirectional　three-level　double-current　LCL-T　resonant　DC　converter　is　proposed　by　combining　the　LCL-T　resonance　with　the　three-level　cascaded　neutral-point　clamp　active　bridge.　Due　to　the　special　pattern　of　cascading　by　the　coupling　transformers,　each　sub-arm　of　the　active　bridge　can　work　independently　or　in　parallel.　Based　on　this,　different　modulation　methods　can　be　designed　to　control　the　input　voltage　of　the　resonant　tank,　and　establish　one-time　and　two-time　quasi-constant-current　(QCC)　modes.　Furthermore,　the　symmetrical　design　of　the　resonant　tank　parameters　is　used　to　achieve　unified　bidirectional　power　transmission　characteristics,　and　a　LCL-T　resonant　QCC　output　controlled　by　normalized　frequency　fn　and　quality　factor　Q　is　researched.　Considering　the　reactive　power　control　and　realizing　zero-voltage　switching　of　switches,　the　filtering　algorithm　of　output　condition　that　satisfies　the　restricted　given　QCC　output　accuracy　is　designed.　Finally,　the　simulation　platform　and　experimental　prototype　are　established　to　prove　that　the　proposed　converter　can　achieve　the　QCC　output　within　a　restricted　given　accuracy　in　each　mode.　©　2023　Electric　Power　Automation　Equipment　Press.　All　rights　reserved.