Patent ID: 8638017

Claim:
In connection with a permanent magnet rotary machine comprising a rotor comprising a rotor core and a plurality of permanent magnet segments embedded in the rotor core and a stator comprising a stator core having a plurality of slots and windings therein, the rotor and the stator being disposed to define a gap therebetween, or a permanent magnet rotary machine comprising a rotor comprising a rotor core and a plurality of permanent magnet segments mounted on the surface of the rotor core and a stator comprising a stator core having a plurality of slots and windings therein, the rotor and the stator being disposed to define a gap therebetween, the rotor wherein each of said permanent magnet segments is an assembly of further divided permanent magnet pieces, each of the divided permanent magnet pieces has a coercive force at a surface and an interior, and the coercive force near the surface of the magnet piece is higher than that in the interior of the magnet piece, wherein each of the divided permanent magnet pieces has a coercive force near the entire surface of all surfaces of the magnet piece that are parallel to a magnetization direction of the magnet piece that is higher than in the interior of the magnet piece.