Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1931. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed June 1, 2010) Includes index (p. [iii-iv]).

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 71-79). Also available on the World Wide Web.

Thesis MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2006 / Reluctance Synchronous Machines (RSM) have, due to their rotor geometry, an inherently high torque ripple. This torque ripple is defined as the deviation of the minimum and maximum torque from the average value. It is unwanted as it indicates uneven pull on the rotor causing deformation of it and hence different air-gaps along the rotor circumference as well as acoustic noise. In applications such as power steering, robotics and radar positioning systems where high precision movement is vital, oscillating torque will lead to the malfunction of these devices and therefore suppressed the use and development of RSMs. Unlike the Induction machine (IM), the RSM has no copper losses in the rotor, which reduces the operating temperature significantly. With the development of electronic drives the quality of the output torque could be improved by means of accurate current- and flux space phasor control methods with much success and made the RSM a possible replacement for the IM. However, reducing torque ripple by means of purely geometrical changes is still a challenge to the machine designer. This thesis will focus on the reduction of torque ripple while leaving the average torque relatively unchanged by changing the rotor geometry. The rotor changes will take place by means of flux barriers and cut-outs while the stator has either semi-closed slots or magnetic wedges. In this work rotor structures with equal harmonic magnitudes but their angles 1800 apart. will be combined to form one machine and identify how torque harmonics respond. The change in average torque and power factor will be evaluated with all geometrical changes made to these machines throughout this work.

The objective of this dissertation is to analyse the performance of a linear induction motor suitable to drive a circular saw blade. A selection of analytical methods available from the field of electrical machine theory was used to investigate the particular type of motor. The theoretical analysis is supported by an extensive experimental investigation. Although LIMs have been designed, analyzed and applied in other applications, significant differences exist between those LIMs and the one used for the new application. These include: the annular shaped motor, the smaller air gap, and the rotor which is thin and made of steel. Because of these differences, the methods used by previous investigators were not sufficient to design the LIM required. The theoretical analysis used a selection of methods described in the literature to quantify the effect of the rotor material, the end effect and the edge effect. New methods are described to analyse the effect of the annular shape, the normal forces on the rotor and the coil connection. In addition, a new consideration in the optimisation of these type of motors is described. An extensive experimental program was undertaken. Six different linear motors were constructed with output powers ranging from one to fifty kWatts. In addition, inverters, dynamometers, flux measurement apparatus, speed measurement, thrust measurement and friction measurement apparatus were designed and constructed. The effects on performance of slot harmonics, winding connections, the end effect and the edge effect were measured. Several contributions to the field of electrical machine theory are presented. The first is a new annular disc motor resistivity correction factor. Second, is the analysis of the effects of poles in parallel versus in series in linear induction motors. Third, is the experimental comparison between odd and even pole designs. The fourth is a second optimum goodness consideration for LIMs, which had not previously been considered. The fifth is the analysis of the rotor/stator attractive force for magnetic rotor double sided motors and a description of the flux (crenelated flux) which causes the force. Finally, a criterion for when the re-entry effect may occur is presented. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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Typescript, etc.

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

No description available.

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