Patent ID: 7411329

Claim:
A permanent magnet synchronous motor comprising: a rotor including: a rotor core; a reversely-arced permanent magnet buried in said rotor core such that an end of said permanent magnet faces an outer wall of said rotor core, said rotor core having an opening between said end of said permanent magnet and said outer wall of said rotor core for preventing demagnetization of said permanent magnet; and a stator including teeth and concentrated windings such that adjacent teeth have different polarities; wherein said rotor and said stator are arranged to satisfy the relationships: Lg<Q<3 Lg; and 0.10 As<Am<0.25 As, wherein: Lg is a size of an air gap between said rotor and said stator; Q is a distance between said end of said permanent magnet and said outer wall of said rotor core; Am is an angle of an arc length of said end of said permanent magnet measured with respect to a central axis of said rotor; and As is an angle of an arc length of each tooth of said stator measured with respect to said central axis of said rotor.