Thesis (Ph. D.)--University of Wisconsin, 1907. / Bound with v. 4, no. 1-v. 4, no. 5 subsequent to publication. Includes bibliographical references (p. 85-88).

M.Ing. (Electrical & Electronic Engineering Science) / This dissertation deals with the design and implementation of a hysteresis machine for high-speed applications. A model is introduced whereby the optimum working point of the machine can be determined. Hence it is possible to make a comparison between different rotor materials with respect to cost, specific energies and overall performance. The development of a compensator for actively controlling the phase angle of the airgap flux density, in order to reduce hunting, is discussed with reference to practical results. A technique for measuring real power in the frequency plane with the aid of a frequency spectrum analyzer, is explained. The design and evaluation of a hysteresis machine is based on practical results obtained from this measuring technique.

M. Ing. / The design of electric motor systems as we know it today, is very important and has a direct influence on the reliability of the system. In this dissertation, recommendations in design are given to obtain a reliable electric motor system. This dissertation covers a literature review of reliability engineering, and this is then applied to an electric motor system in order to determine the reliability of the system. This dissertation is divided into five parts: Problem definition, theory and literature survey, economics of reliability engineering, analysis and synthesis of an electrical motor system, conclusions and recommendations. Part I describes the environment of an electric motor system and presents some fundamental concepts of reliability engineering. It emphasizes the importance of reliability analysis in the design of electric motor systems. Part II describes some theory and literature about reliability. It emphasizes some existing reliability analysis methods for development of electric motor systems. The reliability prediction method is very useful for analysis of electric motor systems. The author emphasizes that economics of reliability engineering should be taken into account in the design process in Part III. The analysis of life cycle costs is very important. Life cycle costs (LCC) usually consist of the initial investment, preventive maintenance costs, repair costs and the costs for production losses and outages due to failures and disturbances. Life cycle costing methodology is useful in analyzing the design, reliability and maintenance during trade off of technical systems and equipments. Part IV focuses a specific electric motor system. Some existing reliability analysis methods are used to analyse reliability of electric motor systems. It is highlighted how to improve the reliability of electric motor systems. Some economics considerations are also presented in this section. The main conclusion reached in this dissertation is that failure data feedback, and accurate records are very important for reliability engineering. The author makes some recommendations for reliability of an electric motor system in design. This dissertation may contain direct information from sources indicated generally by. This is however generally contextualized within the main aim of the research. This is the result of specific communication obstacles.

This thesis proposes a technique to determine and improve the performance of a sensorless speed estimator for an induction motor based on Motor Current Signature Analysis (MCSA). The theoretical concepts underlying the parameter based observer are developed first and then the model of the observer is built using Simulink. The observer is developed based on Model Reference Adaptive System (MRAS). The dynamic performance of the observer and its behavior due to variation of machine parameters is studied. The error in speed estimated using this observer is shown and the ability of MCSA to retune the rotor speed from the stator current spectrum. The spectrum estimation technique has been implemented using a software routine in Matlab. Both the observer and MCSA techniques were implemented practically on an induction motor. The performance of the combined sensorless speed estimation system was tested and verified.

The problem of measuring low values of slip of induction machines is present in most Electrical Engineering laboratories. A rather high accuracy of the determination is necessary for theoretical calculations of motor loading, using equivalent circuit techniques. Conventional methods of determining slip fail to give high accuracy at low values of slip. This thesis presents a solution to this problem by describing the design and construction of a precision slip frequency detector of nominal cost. The principle employed is that of beat frequency comparison of the rotor shaft speed against line frequency. The output of the beat frequency detector actuates a multivibrator-differentiating circuit, the output of which triggers an electro-mechanical counter. A photoelectric pickup device for determining shaft speed is also discussed.

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

No description available.

Approved for public release; distribution is unlimited / Next-generation U.S. Navy destroyers, known as DD(X), will use electric drive motors to meet their propulsion needs instead of the traditional mechanical drives. The use of electric drive motors in naval vessels has spurred the development of high power converters. This thesis examines the feasibility of using an advanced control algorithm known as Sine-triangle Pulse Width Modulation (SPWM) in combination with a Cascaded Multi-Level Converter (CMLC) in order to meet the U.S. Navy's strict requirements. The SPWM control algorithm was designed in Simulink and experimentally tested on a CMLC previously constructed at the Naval Postgraduate School. The controller and converter successfully powered a quarter horsepower three-phase induction motor. / Ensign, United States Navy

Although there are different HEV configurations, they are all based on same kinds of components. After introducing the main components HEVs use, we build up a model which can illustrate the basic idea of HEVs. The analysis of the model helps us to reveal the essential problem of HEV power control. The performance of a HEV depends not only on the individual components but also on how the components are coordinated. The power control system must determine operating points for the components during driving to save energy. The proposed power control approach is based on model predictive control and trying to solve the nature problem of HEV power control by an optimization concept, which makes the approach applicable for all kinds of HEVs. A number of different simulations have been executed to prove the feasibility of the approach. By changing some operational weights, the power control system can achieve different performances. / Another key concept adopted in the power control system is based on the premise that future driving load would affect fuel consumption, as well as the operating modes of the vehicle and the driver behavior do. The proposed power control approach incorporates a driving load forecasting algorithm whose role is to assess the driving environment, the driving style of the driver, and the trend of the vehicle using long and short term statistical features of the past drive cycle. This future driving load information is subsequently used to change the operational weights of the power control approach, such as engine efficiency, battery State of Charge (SOC), engine speed, etc. By this way, the power control approach leads to improved the vehicle's overall performance. / One of the major crises that the world is facing today is the problems of energy. With the beneficial effect on the environment and high energy transformation efficiency in hybrid electric vehicle technology, automobile manufacturers have begun to look more seriously into vehicles with alternative power sources. Aimed at solving the more and more serious problems of energy, HEV has been one of the best practical applications for transportation with high fuel economy. / This dissertation proposes a new power control approach for all kinds of hybrid electric vehicles (HEVs). / To obtain better performance, we use particle swarm optimization (PSO) to find optimal weights for different drive loads. Then, by integrating MPC controller and load forecasting algorithm, a realtime HEV power control system, model predictive power control with load forecasting system (MPC-LF), is developed. Experimental results prove the feasibility of the control system. / Wang, Zhancheng. / Adviser: Xu Yangsheng. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3631. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 132-140). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

In traditional Permanent Magnet Machines, such as electric motors and generators, power is transmitted by magnetic flux passing through an air gap, which has a very low magnetic permeability, limiting performance. However, reducing the air gap through traditional means carries risks in manufacturing, with tight tolerances and associated costs, and reliability, with thermal and dynamic effects requiring adequate clearance. Using a magnetically permeable, high dielectric strength material has the potential to improve magnetic performance, while at the same time offering performance advantages in heat transfer. Ferrofluids were studied as a method for improved permeability in the rotor / stator gap with a combined experimental and computational approach. Results show promise for the ferrofluid technique. An off-the-shelf motor system showed improved performance with ferrofluids vs. fluids of equivalent viscosity, and improved performance vs. an air gap at low RPM. New generator designs showed design dependent performance gains, although some potential for negative performance effects. A proof of concept generator was built and tested, with increased voltage vs. RPM predicted through virtual prototyping, and validated through experimentation, showing ~10% improvement on voltage vs. RPM at the <600 RPM range. More repeatable engineering tests demonstrated a ~30% increase in the voltage / RPM relationship for designs with an isolated stator chamber and a large stator - rotor gap. However, the effects were negative for a similar system with a small stator-rotor gap due to leakage flux effects. New contributions to the body of knowledge in this area include: • Application of the ferrofluid technique to axial flux designs. • Development of a virtual prototype, including variations in the fluid viscosity due to ferrohydrodynamic effects. • Consideration of negative effects of ferrofluid immersion, such as shear losses and increases in leakage flux. • Optimization of the design to eliminate increased viscous losses. The improved design has been designed, built, and tested, featuring isolation of the ferrofluid from the rotating region. This offers all of the performance gain of improved magnetic permeability, while minimizing the offsetting losses from increased shear effects.