Simulation, Design and Test of Brushless, Self-Excited Synchronous Field-Winding Machine

Abstract

The high cost of rare-earth materials has spurred interest in the development of high-performance electric machines which do not require these materials. However, other conventional machine architectures suffer from relatively low efficiency and power density when compared to rare-earth permanent-magnet machines. Synchronous field-winding machines have performance characteristics similar to those of rare-earth magnet machines. However, the power density and cost of conventional field-winding machines are adversely affected by the mechanisms which convey power to the field windings. This thesis presents a brushless, self-excited synchronous field-winding machine design. The rotor of this machine possesses two windings, a field winding and a “transformer” winding, that are connected through a diode rectifier circuit. Using field-oriented control techniques, an AC magnetic field is generated by the stator windings that is always aligned with the transformer winding. A simulation model which combines a finite element model of the machine’s magnetic behavior with a nonlinear circuit model of the diode rectifier is developed and used to design the machine. Experimental results from a prototype machine are presented.