a method and apparatus in which a rotor and a stator define a radial air gap for receiving ac flux and at least one dc excitation coil positioned near the stator end turn to produce dc flux in axial air gaps additive to the ac flux . side magnets and flux - guiding magnets are provided as boundaries separating the side poles of opposite polarity from other portions of the rotor and from each other to define pm poles for conveying the dc flux to or from the primary air gap and for inhibiting flux from leaking from said pole portions prior to reaching the primary air gap . side magnets , side poles , flux - guiding magnets , ferromagnetic end plates , non - magnetic end plates , and ring bands are optionally provided for performance improvement .