Patent ID: 7605510

Claim:
A permanent magnet rotating machine, having a stator and a rotor, the stator having teeth that define slots for holding a stator winding, each of the teeth having a tooth top surface that faces an outer circumferential surface of the rotor, the rotor having main magnetic poles and auxiliary magnetic poles which alternate in the circumferential direction when viewed in cross section perpendicular to the axial direction of the rotor, each of the main magnetic poles having a magnet insert hole for receiving a permanent magnet, wherein: the outer circumferential surface of the rotor comprises first outer circumferential surface portions each having a first curve profile which bulges radially outward and intersects with a d-axis of the assigned main magnetic pole and second outer circumferential surface portions each having a second curve profile which bulges radially outward and intersects with a q-axis of the assigned auxiliary magnetic pole, as viewed in cross section perpendicular to the axial direction of the rotor, and a radius of curvature of the second curve profile is larger than a radius of curvature of the first curve profile, a recess is formed in the second outer circumferential surface portion and in a position to face an end wall of the magnet insert hole which is adjacent to the outer circumferential surface of the rotor, and [{0.08×(g+D)}mm≦h≦{0.6×(g+D)}mm], where g is a minimum distance between the outer circumferential surface of the rotor and the teeth top surface, D is a maximum distance between a virtual outer circumferential surface which has a radius corresponding to the longest distance between the center of the rotor and the outer circumferential surface of the rotor, and the outer circumferential surface portion of the auxiliary magnetic pole, and h is a minimum depth of the recess.