Because　of　the　special　topology　structure,　DC-DC　converter　has　wide　application　prospect　in　multiple　utilization　of　resource,　which　differs　in　capacity　and　voltage　level,　such　as　solar　cell,　fuel　cell　and　wind　power　generation.　In　view　of　off-grid　wind　generation　system,　in　this　paper,　a　novel　single-ended　primary　inductance　converter　(SEPIC)　circuit　structure　is　presented　to　handle　the　big　voltage　fluctuation　after　3-phase　rectifier　so　that　the　supply　to　load　is　stable.