Patent ID: 7579733

Claim:
A rotor comprising: a rotor core having a rotor surface; a plurality of permanent magnets embedded in the rotor core with each of the permanent magnets defining a pole of the rotor, each pole of the rotor having a pole center; a plurality of first non-magnetic layers being located between adjacent pairs of the permanent magnets along the rotor surface, each first non-magnetic layer being continuous or adjacent to a peripheral edge section of one of the permanent magnets in a vicinity between the poles and a vicinity of the rotor surface; and a plurality of second non-magnetic layers being located in a vicinity of the rotor surface at pole center side positions with respect to the first non-magnetic layers, the first non-magnetic layers and the second non-magnetic layers being positioned to cancel 5-th order harmonics or 7-th order harmonics of an induction voltage, and the first non-magnetic layers and the second non-magnetic layers being independent from one another, and the rotor core being interposed between them, wherein an angle θ 1 being measured between a pole center side edge section, in the vicinity of the rotor surface, of the first non-magnetic layer and a position between the poles, and an angle θ 2 being measured between a pole center side edge section, in the vicinity of the rotor surface, of the second non-magnetic layer and the position, wherein 0<θ1<180/(5· Pn ) and 180/(5· Pn )≦θ2≦180×2/(5· Pn ) or 0≦θ1<180/(7· Pn ) and 180/(7· Pn )≦θ2≦180×2/(7· Pn ) where a pole pair number is Pn.