In　this　paper,　a　new　permanent　magnet　synchronous　coupling　(PMSC)　is　proposed　for　switch　machines.　Using　the　principle　of　magnetic　field　superposition,　the　magnetic　field　model　of　this　coupling　is　established　for　the　first　time.　Based　on　the　scalar　magnetic　potential　and　Maxwell　stress　tensor,　the　distribution　of　the　air　gap　magnetic　field　is　derived　in　the　2-D　model,　and　the　analytical　expression　of　the　transmission　torque　is　obtained.　The　accuracy　of　the　analytical　model　is　verified　by　comparing　the　results　from　the　3-D　finite　element　method　(FEM).　The　results　show　that　the　magnetic　field　characteristics　of　the　air-gap　magnetic　field　obtained　by　the　analytical　model　are　in　good　agreement　with　those　calculated　by　the　3-D　FEM.　The　prototype　is　fabricated　and　bench　experiments　are　done.　The　performance　of　the　coupling　and　the　accuracy　of　the　analytical　model　are　verified.　©　2022　IEEE.