published_or_final_version / Electrical Engineering / Master / Master of Philosophy

The Switched Reluctance Motor (hereafter referred to as SRM) requires rotor position information for successful operation. The rotor position, in the present day, is obtained through a mechanical/electrical sensor mounted on the rotor shaft. These transducers are expensive and take additional space on the rotor shaft. An alternative scheme of rotor position sensing is proposed in this thesis which overcomes the disadvantages of existing position sensors. This is achieved by injecting a high frequency control level signal on the stator windings and measuring the response. The response is an indirect measure of the rotor position. The principle, design, and implementation of the sensor is described in this thesis. The proposed sensor is inexpensive compared to the available sensors and is expected to find applications in small and medium size SRM drives. / Master of Science

Brushless Doubly-Fed Machines have potential benefits in variable speed generation and adjustable speed drive applications by combining a robust machine structure with a reduced power converter rating. While recent work has demonstrated feasibility, steady-state performance has not been optimized. The nature of doubly-fed operation causes rotor currents of varying, relatively high frequency. Moreover, the rotor structure deviates from conventional squirrel cages. Consequently, induction machine rotor bar geometries need to be carefully examined and refined for applicability in the doubly-fed system. The present thesis uses finite element analysis to investigate alternative rotor bar design. Two-dimensional finite element analysis is used to investigate basic rotor bar characteristics. Interface with a detailed simulation program enables investigation of assembled rotors, otherwise a three-dimensional analysis problem. Rotor bar geometries for a high speed alternator are investigated. Bar shapes are kept simple to allow manufacturing of the rotor in the absence of the-casting equipment. Rotor prototypes are constructed using custom, laser-cut laminations and experimental results for the alternator verify improved line-to-shaft efficiencies over conventional rotor geometries as well as off-the-shelf alternators. / Graduation date: 1994