An AC/AC converter has been designed and implemented for the purpose of providing a modular drive system with a Brushless Doubly-Fed Machine (BDFM.) This converter is to be used in laboratory testing and also as part of a demonstration system in the field. All hardware needed to start and run the BDFM is now consolidated into a single NEMA standard frame electrical equipment box. This allows easy transportation and setup of the drive system, and will enable the BDFM drive system to be directly compared with existing induction machine based drive systems. Converter subsystem overviews in the body of the text and comprehensive schematics in the appendices of this thesis describe all circuitry included in the drive system. Sufficient construction detail is given to allow for duplication of this converter by qualified technical personnel. While not tailored for mass production, this converter may provide a starting point for a commercially viable design. / Graduation date: 1998

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 97-99). Also available on the World Wide Web.

Thesis (M.S.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 74 pages. Includes vita. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2001.

Thesis (Ph. D.)--University of Chicago, Department of Chemistry, 2002. / Includes bibliographical references. Also available on the Internet.

Thesis--Ph. D., University of Hong Kong, 1981.

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

High power conversion efficiency is desirable in power supplies. Design optimization of on-line power converter is presented in this thesis. High efficiencies over a wide load range, for example 20%, 50% and 100% load, are often required. It is a challenge for on-line pulse-width modulation (PWM) converters to maintain good efficiencies with light load as well as full load. A two-stage multi-objective optimization procedure is proposed to optimization power converter efficiencies at 20%, 50% and 100% load. Two-FET forward prototype converters are built to verify the optimization results. The LLC (abbreviation of two resonant inductor L and one resonant capacitor C ) series resonant converter can provide high power conversion efficiency because of the resonant nature and soft switching. The design of LLC resonant converter is more difficult than that of PWM converters since the LLC resonant converter has many resonant modes. Furthermore, the LLC resonant converter does not have analytical solution for its resonant operation. In this thesis, a systematic optimization procedure is proposed to optimize LLC series resonant converter efficiency. A mode solver technique is developed to solve LLC resonant converter operations. The proposed mode solver employs non-linear programming techniques to solve a set of LLC state equations and determine the resonant modes. Loss models are provided which serve as the objective-function to optimize converter efficiency. Optimization results show outstanding efficiency performance and experimental agreement with optimization. The optimization work extends to the LLC resonant converter with power factor correction (PFC) circuits where the effect of LLC converter input voltage variation cased by the PFC circuit is considered. Detail comparisons of PWM converter and LLC resonant converter loss profiles are also presented. The reasons that LLC resonant converter has higher efficiency are given and supported by quantitative data. Converter lifetime is highly related to component losses and temperature. The lifetime analysis is presented. The analysis reveals that the LLC resonant converter output capacitor is the weakest component concerning life. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

M. Tech. Electrical Engineering. / Aims to analyze, design and develop a transformer-less 5-level converter topology with an improvement in the output waveform and to investigate its suitability for AC/DC, DC/AC and back-to-back configuration.

Graduate