Polyphase stepper motor - has axially centred permanent magnet rotor, and magnetic stator circuit having at least two parts, each comprising two principal poles, and intermediate poles

摘要

The motor comprises a permanent magnet rotor (3) with N pairs of poles arranged around a central axis, with the magnets extending parallel to the axis. A magnetic stator circuit has at least two phases (4a,5a;4b,5b), each formed of two principal poles having min slots or teeth extending perpendicular to the axis. Each stator circuit is connected at each end of the slot to an end of a core carrying a coil. An intermediate polar piece (6a,6b) extends in the same plane as the principal poles, and has intermediate slots located w.r.t. the main slots and engaged between them. The rotor extends parallel to the poles. ADVANTAGE - Has large number of poles, with simple construction. Reduced parts. Increased precision of relative positioning of poles.