Permanent magnet motor

A permanent magnet motor has a number of permanent magnets forming permanent magnet poles. Each magnet has an outer surface that is an arc surface with a convex middle. An inner surface of the magnet is a curved surface with a concave middle. The curved surface has an arc surface section and two planar surface sections. The arc surface has a pole arc angle α of 0.7 to 0.96, and the ratio of an arc angle β of the arc surface section to the pole arc angle α is 0.15 to 0.35. The shape of the inner surface of the magnet creates uneven air gaps between the rotor poles and the stator core poles. This reduces cogging torque, increases the motor efficiency, and reduces the motor noise.