Permanent-magnet motor including v-shaped permanent-magnet pairs

A permanent-magnet motor comprising:

• a stator provided with a stator core having a plurality of teeth and a plurality of slots and an armature winding having a plurality of multiphase windings that are wound around the plurality of teeth and are contained in the plurality of slots;
• and
• a rotor provided with a rotor core facing the stator core via a predetermined air gap, a plurality of permanent magnets embedded in the rotor core, and a plurality of magnetic-field poles,
• wherein the plurality of permanent magnets form a plurality of permanent-magnet pairs in each of which end surface portions having a different polarity substantially face each other,
• wherein each of the plurality of permanent-magnet pairs is configured with a pair of the permanent magnets that are arranged in a v-shaped manner in such a way that the distance between the portions of the plurality of permanent magnets, facing each other at the outer side in the radial direction of the rotor core, is smaller than a distance between the portions thereof, facing each other at the inner side in the radial direction of the rotor core, and
• wherein a magnetic-field pole is formed of part, of the rotor core, that is situated between the adjacent permanent-magnet pairs,
• wherein when it is assumed that R denotes the length of the outer circumference of the rotor core, Wc denotes the circumferential-direction maximum width, at the foregoing magnetic pole, of the rotor, Lc denotes the axle-direction length of the permanent magnet, Wm denotes the length of the permanent magnet in a direction perpendicular to the axle direction, and W denotes the total weight of the permanent magnets for forming one piece of the magnetic-field pole, the rotor is formed in such a way as to satisfy the equation below
• [−30.3×W/Lc+89−1.3]≤[Wc×R/Wm≤−30.3×W/Lc+89+1.3].