Analytical ModelforDesign ofHigh-Speed Slotless Brushless Machines withSMCStators

circulation oftheEddycurrents isconcentrated inthedepth Abstract- Thispaper presents ageneral analytical model ofthelamination. Thedesign ofhighspeed machines with forthedesign ofhigh-speed slotless permanent magnetSMC stator cores isacomplex problem because aprecise brushless motors equipped withsurface-mounted magnets and knowledge oftheeddycurrents circulation andtheir effects usingsoftmagnetic composite material (SMC)inthestator.that isclosely related tothemachine structure, dimensions Theelectromagnetic modelisformulated inpolar coordinates. andbasedontheprediction ofthetwo-dimensional magneticandsupply, iSessential. field distribution inthemagnets/air-gap/windings/stator core Thispaper presents a first approach toaspecific design regions, produced bythemagnets andthestator currentsmethodology ofthis kindofmachines equipped withsurface windings. Ittakes intoaccount theeffects ofthestator core mounted magnets. A design toolhasbeendeveloped that eddycurrents induced inthemassive homogeneous SMC takes into account theeffects ofthestator coreeddycurrents material. Different machineperformances likethe instantaneous torque underbrushless operation andthetotaliducedinthemassive homogeneous SMC material. Itis magnetic losses areevaluated. Theanalytical design modelis using ananalytical modelbasedontheprediction ofthe validated byFEanalysis interms ofmagnetic field distribution two-dimensional magnetic field distribution inthemachine andtotal stator coreloss. Theinfluence ofthestator yoke structure, duetothemagnets andthearmature currents. The thickness andtheSMC material conductivity onthemotor modelisformulated inpolarcoordinates andittakes performances isinvestigated. Experimental results aregivenaccount oftheeffect oftheeddycurrent reaction field and forthestator magnetic losses. thetimeandspaceharmonics ofthemagnetic field. IndexTerms-Permanent magnet machines, slotless, highDifferent machineperformances liketheinstantaneous speed, magnetic field, model, design, losses, eddycurrents, torque underbrushless operation andthetotalmagnetic SMC. losses areevaluated. Thedeveloped modelisvalidated by FEanalysis andemployed toinvestigate theinfluence ofthe stator yokethickness andtheSMC conductivity onthe