Abstract: A permanent magnet rotor includes a shaft, a rotor core fixed to the shaft, and multiple magnet sets. The rotor core has multiple groove sets for receiving the magnet sets. Each groove set has two grooves spaced apart by a first section of the rotor core. The first section has a width gradually decreasing from a radially inner end to a radially outer end. Each groove has a width gradually increasing from a radially inner end to a radially outer end. Each magnet set includes two magnets respectively received in the grooves of a respective groove set. The magnets of a magnet set are magnetized in a same direction, and every two adjacent magnet sets are magnetized in contrary directions creating multiple magnetic poles. The number of magnetic poles is equal to the number of magnet sets.