A　novel　common　mode　(CM)　noise　suppression　scheme　of　transformer　was　proposed.　By　adding　a　layer　of　shielding-cancellation　winding　in　the　transformer,　it　can　not　only　completely　block　the　electric　coupling　between　the　secondary　winding　and　the　primary　winding,　but　also　cancel　the　CM　noise　of　the　primary　or　the　secondary　side　to　suppress　the　CM　noise　flowing　through　the　transformer.　Combined　with　the　characteristics　of　CM　noise　of　LLC　converter,　the　design　principle　and　calculation　process　of　shielding-cancellation　winding　were　given.　The　CM　noise　of　three　transformer　structures　without　shielding　layer,　fully　shielded　copper　foil　and　shielding-cancellation　winding　were　tested　and　compared.　The　experimental　results　show　that　the　CM　noise　suppression　effect　of　the　shielding-cancellation　winding　is　the　best　among　the　three,　which　verifies　the　effectiveness　of　the　shielding-cancellation　winding　in　suppressing　CM　noise.　©2022　Chin.Soc.for　Elec.Eng.