Permanent magnet motor

A permanent magnet motor comprising:

• a) a stator including an annular stator core and a plurality of stator windings wound on the stator core so that a plurality of phases are composed;
• and
• b) a rotor rotatably mounted with a predetermined air gap between the same and an inner peripheral face of the stator core, the rotor including a rotor core having a plurality of slots and a plurality of permanent magnets embedded in the slots respectively, the rotor being rotated when the stator windings are sequentially energized;
• wherein each permanent magnet has a generally arc-shaped cross section and is embedded in the slot so that a convex portion thereof is directed toward a rotor axis;
• each permanent magnet is magnetized so that directions of easy magnetization thereof are concentrated on a point C at a side of center of curvature thereof;
• the relation between a distance L between the point C and a center line passing the center of each permanent magnet in the direction of the thickness thereof and a mean radius of curvature R of the permanent magnets is shown by the following expression:
• 1.8.times.R.ltoreq.L.ltoreq.5.times.R.
• 2.