Recently,　many　nonisolated　high-gain　dc-dc　converters　have　been　proposed.　However,　most　of　these　converters　operate　in　a　hard　switching　environment　and　have　high　diode　reverse　recovery　currents.　Besides,　the　boost　capability　of　these　converters　still　needs　to　be　further　improved.　To　address　the　above　shortcomings,　a　novel　single-switch　soft-switched　high　voltage　gain　dc-dc　converter　based　on　a　single-ended　primary　inductor　converter　(SEPIC)　topology　is　presented　in　this　article.　The　proposed　converter　utilizes　quasi-resonant　(QR)　operation　to　achieve　soft-switching　conditions　and　alleviate　the　diode　reverse　recovery　problem.　In　addition,　the　proposed　converter　integrates　a　Y-source　network,　which　makes　the　voltage　gain　regulation　more　flexible.　The　steady-state　analysis　and　design　consideration　have　been　presented.　The　loss　analysis　has　been　conducted.　A　small　signal　analysis　has　been　carried　out.　Comparisons　between　various　converters　have　been　performed.　Finally,　a　200　W　prototype　validates　the　effectiveness　of　the　proposed　converter.　When　the　output　power　reaches　200　W,　the　efficiency　of　the　proposed　converter　is　95.238%.　©　1982-2012　IEEE.