Abstract: A self-starting synchronous or stepping motor has at least two phases, a permanent magnet rotor and a stator including individually excited and inwardly facing main stator poles. The stator poles and rotor poles have a predetermined spacing of .tau.p. The stator poles are combined in groups of alternate polarity. The groups are displaced by a predetermined angle. At least one windingless auxiliary stator pole of approximately one-half of the width of the main stator pole is provided per group in addition to the main stator poles. The total number of stator poles is at least equal to the number of rotor poles. Additional auxiliary poles may be either half-pole widths or pointed shape. Embodiments of two-phase and three-phase synchronous motors are disclosed.

Abstract: In the motor disclosed, five stator windings are distributed on u groups each having five main poles and coacts with a permanent magnet rotor. Each pole has n+1 pole teeth. The stator windings are connected in series or parallel to form five connecting points. A control switches five switches having an armature connected to a connecting point between a positive and negative potential so as simultaneously to energize the windings as required. The control then shifts the short-circuited condition to other windings in cyclical sequence while energizing the remaining four windings at any time. The pole divisions exhibit the relationshipsT.sub.P = nT.sub.S +.alpha.; .alpha.=T.sub.S (K+ 0.6).tau..sub.p ' = nT.sub.S +.beta. ; .beta.=T.sub.S (K'+0.6)the ratio of the rotor tooth widths to stator tooth widths at the outer diameter of the rotor is equal or smaller than unity. The number of rotor teeth Z.sub.R = u (5n+4K+K'+3). In this relation n, K, and K' are whole numbers and T.sub.P, T.sub.P ' and T.sub.