Phase-shifted　full-bridge　DC-DC　converter　with　zero-voltage　and　zero-current-switching　(ZVZCS)　is　chosen　in　high　voltage　and　power　capacity　for　high　efficiency　and　power　destiny.　Leading-leg　switches　turn　on　with　ZVS,　which　is　easy　to　realize;　lagging-leg　switches　turn　off　with　ZCS,　which　is　the　key　point.　In　this　paper,　the　detail　analysis　of　ZCS　achieved　with　two　diodes　will　be　given.　When　the　output　voltage　should　be　tuned　in　a　large　range,　the　interval　of　the　current　falling　down　to　zero　should　be　considered　as　resonance　of　LC,　and　the　voltage　of　blocking　capacitor　should　be　not　treated　as　a　constant　anymore.　Furthermore,　to　suppress　the　reverse　current　and　voltage　spike　of　output　rectifier　diodes,　two　small　saturable　inductors　are　connected　with　the　diodes　in　series.　The　method　is　far　more　effective　than　other　snubbers,　while　it　will　influence　the　ZCS　adversely.　A　more　precise　calculation　of　ZCS　is　deduced.　Simulation　and　experiment　are　followed　to　verify　the　analysis.　A　prototype　is　built　with　three-phase　380VAC/50Hz　input,　100A/50V　adjustable　output.　©　VDE　VERLAG　GMBH　·　Berlin　·　Offenbach.