Thesis (Ph. D.)--University of Hong Kong, 1996. / Includes bibliographical references.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1925. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed September 16, 2009) Includes bibliographical references (p. 30) and index (p. 31-32).

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.

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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A novel control strategy for segmented long-stator permanent magnet linear synchronous motors is presented that is particularly suited to ropeless hoisting. The stator (primary) is segmented into modular sections that are shorter than the moving reaction plate (secondary) and a single voltage source inverter per conveyance is used to power the energised sections. Efficient partial excitation of the stator is achieved with an intermediate switching layer placed between the stator sections and the inverter. The common voltage supplied to the sections is controlled with any standard motor vector control technique. Computer simulation and a purpose-built laboratory prototype show the strategy to be effective. There is scope for future research into full sensorless control of the proposed arrangement and a method of further modulating the supply voltage for those stator sections that are only partially covered by the reaction plate, particularly when operating at higher speeds. Stemming from initial efforts to mathematically model the linear motor, a novel electromagnetic modelling approach was formulated. This hybrid magnetic-equivalentcircuit (MEC) and finite element method (FEM) approach is suited to efficient dynamic simulation and is explicated with a worked example. The method yields accurate results when compared with pure FEM. An MEC formulation is used for highly-permeable polygonal regions, whereas the magnetic field outside these regions is solved, by superposition, as the combined effect of boundary conditions that interface with those MEC regions and any magnetic sources. The required parameter sets for solving the field outside the regions represented as MECs are purely dependent on the geometry of the problem space and are thus precomputed. The force acting on a chosen group of moving components is calculated using an approximation of the Maxwell Stress Tensor method. Future research could address the present limitation that the highly-permeable regions are meshed using exclusively-rectangular flux tube elements. A dynamic simulation model that caters for the discontinuities of a segmented stator was ultimately derived using an extended space-vector approach and its implementation as a generic Simulink R blockset is detailed. The motor parameters are determined from static FEM solutions over the range of reaction plate displacement, assuming no magnetic saturation.

An integrated starter/alternator (ISA) has been proposed for the future 42 V PowerNet, which combines both starter and alternator functions into a single electrical machine with bidirectional power flow ability. This thesis presents analysis, design, modeling and experimental results of the direct torque controlled ISA system based on a low voltage induction machine. The classical direct torque controlled ISA based on switching-table is systematically for an ISA evaluated in this thesis. The simulation and experimental results show that the direct torque control (DTC) concept can be successfully extended to the ISA application. An improved DTC of the ISA based on direct stator flux vector is presented to reduce the drawbacks of high torque and flux ripples of the classical DTC. Robust design of the controller ensures the system is not sensitive to the variation of rotor resistance. By controlling the electromagnetic torque of the induction machine quickly, the required dc bus voltage can be well regulated within the 42 V PowerNet specifications. Another improved DTC of the ISA with direct torque and flux control is also studied. Compared to the direct flux vector control scheme, the calculation of the commanded voltage vector in this scheme only requires the derivative of the stator flux magnitude, which is a dc quantity. In addition, both torque and flux are regulated directly with two independent closed-loops. This scheme is relatively insensitive to the noise. The thesis proposed compensation methods to reduce the effects of switch voltage drops and dead-time on the estimation of the stator flux. Experimental results confirm that the estimation error is reduced with compensation for both motoring and generating modes of the ISA. A closed-loop type of sliding mode flux observer is proposed to reduce the estimation error of the stator flux. Both Simulation and experimental results confirm that the proposed sliding mode observer is insensitive to the stator resistance variation and sensor offsets. A loss minimized scheme with power factor control for the ISA is proposed in this thesis. It provides a simple solution for the efficiency improvement of the induction machine without requiring any speed or load information. The effectiveness of the direct torque controlled induction machine for an integrated starter/alternator system has thus been confirmed and well supported by the studies presented in this thesis.