Permanent magnet synchronous motor

A permanent magnet synchronous motor comprising a stator and a rotor placed with the stator by way of a gap therebetween, the permanent magnet synchronous motor comprising:

• the rotor includes a rotor core made of a magnetic material, and a plurality of permanent magnets is placed on a surface of the rotor core where a shape of the permanent magnet whose shape of a face opposes to the stator is made in a circular arc shape;
• the rotor core includes one or more protrusions radially projecting toward a stator core of the stator, and the permanent magnet includes a recessed portion with which the protrusion is fitted in;
• and
• when a shortest distance between outmost part of the recessed portion of the permanent magnet and an outer periphery's circular arc portion of the permanent magnet is defined as parameter L1, and
• when a shortest distance between the recessed portion and the outer periphery's circular arc portion is defined as parameter L2 where the shortest distance L2 passes through an intersection point at which a tangential line of outmost part on the recessed portion intersects with a parallel line, which defines as its start point a point from which a changeover to the recessed portion of the permanent magnet occurs from an adhesion surface between the permanent magnet and the rotor core, and which is in parallel with a radial line extending from a center of a shaft of the rotor toward a center of the permanent magnet,
• the permanent magnet includes the recessed portion that satisfies L1≤L2, wherein
• the rotor core includes a plurality of protrusions per one pole, and includes a protrusion aggregate set forming the plurality of protrusions as one group of protrusions, and wherein
• recessed portions are formed, on a circumferentially outer side of the protrusion aggregate set, so that a shortest distance L2 between the recessed portions on a circumferentially outer side and an outer periphery's circular arc portion of the permanent magnet satisfies L1≤L2.