Permanent magnet rotor

A rotor for an electric motor, comprising:

• a shaft;
• a plurality of permanent magnets;
• and
• a rotor core fixed to the shaft, the rotor core comprising:
• an inner annular portion defining a central hole for receiving the shaft;
• and an outer annular portion comprising a plurality of sector segments arranged in a ring,
• wherein the sector segments comprise a plurality of first sector segments and a plurality of second sector segments arranged alternately, adjacent sector segments defining a slot there between for accommodating the magnets, inner radial ends of the first sector segments being separated from the inner annular portion, and inner radial ends of the second sector segments being connected to the inner annular portion by respective connecting arms;
• each permanent magnet is respectively disposed in a corresponding one of the slots and extend in radial and axial directions of the rotor core;
• and
• a plurality of elastic members compressively positioned between inner radial ends of the permanent magnets and the inner annular portion of the rotor core.