Patent ID: 7902707

Claim:
An anisotropic permanent magnet motor comprising: a stator which includes a stator core provided with an annular stator yoke, a plurality of teeth protruding from the stator yoke in a radial direction, and a slot formed between two adjacent teeth and a plurality of coils wound around the teeth; and a rotor which includes a cylindrical rotor yoke and an anisotropic permanent magnet disposed on a surface of the rotor yoke facing the teeth of the stator with a gap therebetween, wherein the anisotropic permanent magnet has a section defined by a boundary angle θr so as to have a magnetic pole center located at the center thereof, the anisotropic permanent magnet being magnetized therealong in orientation directions which are each normal to an outer-peripheral surface within the section defined by the boundary angle θr and incline toward the magnetic pole center outside the section in such a manner that an inclining angle of a respective orientation direction measured from a direction normal to the outer-peripheral surface increases continuously progressively from zero as being away from the magnetic pole center but does not exceed 90 degrees, wherein relation θp/θc=3×a stands, where an angle for each pole is denoted by θp, an angle for one cycle of cogging torque generated by the anisotropic permanent magnet is denoted by θc, and a natural number is denoted by a, wherein when a maximum value of the cogging torque in a range of θr/θc≦{(θp/θc)−2} is denoted by an allowable maximum value of the cogging torque, θr/θc corresponding to the cogging torque equal to the allowable maximum value in a range where θr/θc satisfies a relationship of {(θp/θc)−2}≦θr/θc≦{(θp/θc)−1} is obtained, and wherein when the obtained θr/θc is denoted by P, an angle of θr is set so that θr/θc is not more than P.