Brushless Self-Excited Synchronous Field-Winding Machine With Five- and Higher-Phase Design Using Independently Controlled Spatial Harmonics

In this article, a novel brushless self-excitation scheme for synchronous field-winding machines is presented. This scheme uses an AC stator with five or more phases to create two independently controlled rotating magnetic fields at different spatial harmonics, allowing independent magnetic coupling with different rotor windings. The rotor of the proposed machine possesses a field winding, transformer windings, and a diode rectifier that converts induced AC voltages in the transformer windings into a DC voltage for the field winding. A design for a five-phase stator configuration is developed using finite-element analysis tools, and simulation results at different motor speeds are presented to validate the proposed brushless scheme. Torque and power characteristics of the brushless machine are compared with similarly-sized interior permanent magnet and induction machines.