Permanent magnet synchronous motor and rotor thereof

The invention provides a permanent magnet synchronous motor and a rotor thereof, the rotor comprises a rotor core (10) and a plurality of permanent magnets (20), grooves (11) and bulges (12) are alternately distributed on the outer peripheral surface of the rotor core (10), and the grooves (11) are arranged at equal angle intervals and penetrate through the rotor core (10) along the direction parallel to the axis of the rotor core (10); permanent magnets (20) are fixedly installed in the grooves (11), the permanent magnets (20) and the protrusions (12) form first magnetic poles and second magnetic poles which are alternately distributed in the circumferential direction and are opposite in polarity on the outer circumferential face of the rotor iron core (10), and the pole-arc coefficient of the permanent magnets (20) is set to be larger than 1. The rotor core (10) forms a magnetic pole opposite to the polarity of the permanent magnet (20), so that the pole-arc coefficient of the permanent magnet (20) can be s