PURPOSE: To halve a field magnet by putting the armature windings not lying one upon the other in double multiphase windings, and making use of a plurality of components of generated ampere patterns, and making the magnetizations of corresponding field magnets asymmetric.
CONSTITUTION: Armature coils 1-2 are arranged not to lie one upon another on the armature 1 fixed to a rotary shaft 3, and each coil (1)-(3) is connected to positive and negative power sources and + and - in order through commutator pieces 2 at intervals of 60°, accompanying the rotation of the armature 1. Two field magnets 4 having the S poles and N poles corresponding to the coils (1)-(3) are attached to one part each of a bracket 6 to which a bearing 5 is set, and residual parts are nonmagnetized. By the composite compounds of the magnetic fluxes generated by supplying the coils (1)-(3) with currents from the commutators 2 in order, and the magnetic fluxes of the field magnets 4, the armature 1 is rotated. Hereby, even if the number of field magnets is halved, the reduction of generated torque is prevented.