We　present　an　analytical　method　to　study　magnetic　fields　in　permanent-magnet　brushless　motors,　taking　into　consideration　the　effect　of　stator　slotting.　Our　attention　concentrates　particularly　on　the　instantaneous　field　distribution　in　the　slot　regions　where　the　magnet　pole　transition　passes　over　the　slot　opening.　The　accuracy　in　the　flux　density　vector　distribution　in　such　regions　plays　a　critical　role　in　the　prediction　of　the　magnetic　forces,　i.e.,　the　cogging　torque　and　unbalanced　magnetic　pull.　However,　the　currently　available　analytical　solutions　for　calculating　air-gap　fields　in　permanent　magnet　motors　can　estimate　only　the　distribution　of　the　flux　density　component　in　the　radial　direction.　Magnetic　field　and　forces　computed　by　the　new　analytical　method　agree　well　with　those　obtained　by　the　finite-element　method.　The　analytical　method　provides　a　useful　tool　for　design　and　optimization　of　permanent-magnet　motors.