To　improve　the　efficiency　of　isolated　bidirectional　dc–dc　converters　for　off-board　dc　charging　over　a　wide　voltage　gain,　such　as　dual　active　bridge　(DAB)　and　inductor-inductor-capacitor　(LLC)　resonant　converters,　this　article　proposes　an　approach　to　reconfiguring　transformer　turn　ratio　using　multibridge-legs　(RTTMBL).　The　proposed　RTTMBL　approach　reconfigures　a　large　number　of　turn-ratio　combinations　by　adding　a　few　auxiliary　components.　The　different　combinations　of　turn　ratio　are　selected　for　different　operating　conditions　to　match　the　primary　and　secondary　voltages　of　the　converter,　obtaining　a　lower　inductor　rms　current　and　a　wider　zero-voltage　switching　(ZVS)　range,　thus　reducing　conduction　and　switching　loss.　This　article　first　analyzes　the　principle　of　the　proposed　approach　and　describes　the　application　of　RTTMBL　on　DAB　(DAB-RTTMBL)　converter.　Second,　the　DAB-RTTMBL　is　compared　with　the　existing　solutions　regarding　inductor　rms　current　and　ZVS　range.　Finally,　a　DAB-RTTMBL　converter　prototype　with　a　power　of　1kW　and　a　voltage　gain　varying　from　0.4　to　2.5　is　built　to　verify　the　effectiveness　of　RTTMBL,　which　has　six　turn-ratio　combinations.　The　results　demonstrate　the　great　potential　of　the　proposed　RTTMBL　for　wide-voltage-gain　applications.　©　1982-2012　IEEE.