Stepping motor with salient pole stator - has excitation coils mounted on limbs instead of salient poles

摘要

A stepping motor with salient pole stator, with improved use of the construction material has a stator of laminated construction with typically four salient poles (P) joined by yoke sections (J) giving a square outline. The excitation coils (Ia, Ib, IIa, IIb) are located on the yoke limbs instead of the salient poles. The space available is thus better utilised and larger coils giving freater flux density can be employed without increase in active core material. Diametrically opposite coils are connected in series. The rotor can be made of a ceramic magnet having two poles in the case were a four pole stator is employed. In the non-magnetised axis, the ceramic has approximately the same reluctance as air, thus the assembly need not be particularly accurate with respect to radial air gaps between stator and rotor.