The quest for energy is leading the industry into drilling deeper wells. Typically, a temperature gradient of 1°C/150 ft can be expected, with bottom hole temperatures reaching beyond 200°C in many areas of the world. Moreover, the increased recovery benefits and cost reductions possible with the use of horizontal and multilateral wells has triggered a need for higher power energy conversion systems in bottom hole assemblies, such as rotary steerable tools and downhole tractors. The concepts developed throughout this work address some of these new needs. This research investigated improvements, novel solutions and considerations that will lead to significant advantages in terms of reliability, extended temperature operation, increased power capability and reduced size and cost of compact harsh environment energy conversion systems. Improvements to both the electromechanical subsystem and the power electronic subsystem are introduced. Air gap viscous losses were shown to a have a significant effect on the optimal design of submersible PM (permanent magnet) machines, and a design procedure to account for this loss component in the design was developed. The application of a dual winding exterior rotor PM machine in a downhole environment enabled a significant increase in the application’s torque capability, provided protection against generator winding over voltage, and reduced parts count. Comprehensive switching device qualification, testing, and simulation lead to a simple failure mitigation technique for the operation of the most suitable devices at elevated temperature. A flying capacitor multilevel inverter was then successfully constructed and temperature tested. A novel motor drive concept suited for elevated temperature oil filled environment applications concluded the research.

Single-phase brushless fan motor is investigated in this thesis and is fabricated by UMC 0.5 m double-poly, triple-metal, N-Well CMOS process for notebook micro fan motor applications. H-bridge and embedded power mos architecture are used in implemented driver circuit, and an external capacitor is needed for pulse width modulation speed control. A comparator with hysteresis and digital lock detection and auto self-restart function are also implemented in this thesis. Besides, in order to prevent the rush current in output stage, the switch operation of power mos transistors are controlled individually.

As deregulation of the electric power system in the United States unfolds, many customers are experiencing changes in their billing rate structure. Some face the addition of power factor penalty tariffs, and seek ways to minimize the added burden. The installation of entrance capacitor banks is the common response, but fails to take complete advantage of capacitor abilities. Other project designs exist that can harness these advantages to the full benefit of the customer. This work will show that distributing shunt capacitors in parallel with induction motors will elevate power factor and voltage, and also decrease ohmic losses in the wiring and protection devices that supply the motor. This reduction often produces a better overall economic solution due to energy savings. The distribution of capacitors at induction motors reduces the reactive current in the branch of the distribution system that supplies them. A reduction in the total current flowing to the motor along the distribution system results in smaller losses throughout the system. As losses diminish, the total real power drawn through the distribution system is lessened, and electric bills are reduced. This alternative to entrance capacitor banks is not as commonly implemented. A misconception that the resistance in facility distribution systems is relatively low has discouraged distributed motor capacitor installation for overall facility power factor correction, in favor of entrance capacitor banks. We will show that the resistance in the distribution system is higher than typically thought, that motor capacitors can exploit this fact, and can often economically outperform entrance capacitor banks which are terminated at the point of incoming utility power. Motor capacitors are not a new technology. They are commercially available off the shelf technology, suitable for power factor correction for induction motors. Distributed capacitors can be utilized for all significantly sized induction motors in a facility. The elevation in power factor and voltage, reduction in reactive current and real power are calculated, and trends are observed. The matter is considered from both the standpoint of engineering and economics to provide an integrated study.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 118-130).

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 129-138).

Thesis (Doctoral)--Katholieke Universiteit Nijmegen, 1998. / Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xi, 101 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 72-76).

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 64-66). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 64-66). Also available on the Internet.

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 96-105). Also available for download via the World Wide Web; free to University of Oregon users.