Kabushiki Kaisha Toshiba

Mayumi So

Shigeya Tanimoto

In a permanent magnet motor, a stator includes an annular stator core and a plurality of stator windings wound on the stator core so that a plurality of phases are composed. A rotor is rotatably mounted with a predetermined air gap between it and an inner peripheral face of the stator core. The rotor includes a rotor core having a plurality of slots and a plurality of permanent magnets embedded in the slots respectively. Each permanent magnet having a generally arc-shaped cross section is embedded in the slot so that its convex portion is directed toward a rotor axis. Each permanent magnet is magnetized so that directions of easy magnetization 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 expression, 1.0.times.R.ltoreq.L.ltoreq.7.5.times.R.

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Kakamigahara, Japan

Mayumi So