A single-stack variable reluctance stepper motor features a salient-pole stator with concentrated windings mounted directly on the stator poles. The number of phases is determined by the connection configuration of these windings, typically comprising three or four windings. The rotor is constructed from ferromagnetic material and contains no windings.
Both the stator and rotor are made of high-quality, high-permeability magnetic materials, requiring only a small exciting current to produce a strong magnetic field. When a DC source is applied to a stator phase via a semiconductor switch, a magnetic field is generated, causing the rotor axis to align with the stator field axis.