Three-phase hybrid type stepping motor

Abstract

A three-phase hybrid type stepping motor includes a stator having 12 salient poles 1.sub.1, 1.sub.2, 1.sub.3, . . . , 1.sub.11, 1.sub.12. The stator salient poles having the number a of stator teeth 3 and those having the number (a+1) of stator teeth are disposed alternately and a pitch .tau..sub.s1 of the number a of stator teeth and a pitch .tau..sub.s2 of the number (a+1) of stator teeth satisfy the relation of .tau..sub.s1 .gtoreq..tau..sub.s2. A pitch angle formed by central lines of the salient poles and the stator teeth disposed in the salient poles is an equal pitch of 30 degrees and the number Z.sub.R of rotor teeth being given by Z.sub.R =12n.+-.2 or Z.sub.R =12n.+-.4 (where the numbers a and n are integers equal to or larger than 1). The three-phase stepping motor has excellent characteristics in vibration, resolution and high-speed operation as compared with a two-phase stepping motor and its driving circuit can be made simple and low-cost in manufacturing.

Dependencies are inferred from the claim text.