New concept of permanent magnet excited synchronous machines with improved high-speed features

Permanent magnet (PM) excited synchronous machines used in modern drives for electro-mobiles suffer in high speed regions from the limited battery-voltage. The field weakening requires machine designs with reduced power conversion properties or oversize of the power converter. A new concept of such machine features PM excitation, single teeth winding and an additional circumferential excitation coil fixed on the stator in the axial center of the machine. By the appropriate feeding of this coil, the amplitude of the voltage effective excitation field can be varied from zero to values above those of the conventional PM-machines.