Patent ID: 8269392

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 having a plurality of coils, 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 having a plurality of coils, 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 two or more divided permanent magnet pieces, each of the divided permanent magnet pieces has a coercive force at a surface and an interior, the coercive force near the surface of the magnet piece is higher than that in the interior of the magnet piece, and the assembly allows for electrical conduction between the magnet pieces in the absence of an insulating layer capable of complete electrical insulation between the magnet pieces.