PROBLEM TO BE SOLVED: To elucidate the theory of vernier method, and in particular provide an effective vernier method, capable of improving a torque waveform because the vernier method unequalizing the pitches of the denticles of a stator and a rotor were examined to reduce cogging torque generated, when the conventional three-phase hydride stepping motor is not energized in a winding, however, the examination were insufficient that a sufficient effect has not be obtained yet.;SOLUTION: In the three-phase hybrid stepping motor, the cause of the generation of torque waveform distortion is considered that the permeance between the denticles provided respectively on a stator magnetic pole and a rotor magnetic pole change with the rotation of the rotor, and the change has certain regularity. The denticles provided on the front end of the stator magnetic pole are disposed, so that the pitch of the denticles between respective groups is different from that of the denticles in the respective groups, by grouping the denticles into two or three groups to substantially zero the sum of third harmonic vectors of the permeance of the respective denticles in the respective groups, and substantially zero the sum of fifth harmonic vectors of the permeance of the respective groups.;COPYRIGHT: (C)2001,JPO
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