Abstract: The invention relates to an electric motor comprising a rotor and a stator, one of the two being a slotted armature comprising a number R of slots, while the other comprises a number 2P of magnetic poles. Of the 2P angular gaps between the centers of the polar faces of two adjacent magnetic poles, (2P−1) gaps are each equal either to a1=(360°/2P)−b, or to a2=(360°/2P)+b, the angular distance b being equal to 360°/2PR.

Abstract: In an alternating current synchronous servomotor, a disk-shaped rotor (20) is arranged between two stator halves having each a coil with leads extending in the radial direction. The rotor (20) comprises an even number of flat permanent magnets (57) forming an annular series around a hub (55) and of which the flat sides form the north and south poles (N,S) alternating in the series. The circonference of the hub (55) presents planar surfaces (55A) separated by edges (55B). A planar delimitation surface (57A) of one of the permanent magnets (57) bears on each of said peripheral surfaces (55A). A bandage (66) surrounding the delimitation surfaces (57B) of all the permanent magnets (57), which are radially directed to the outside, secures the latter to the hub (55) and connects them by means of the planar surfaces (55A, 57A), mechanically to the hub against rotation.