Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on August 11, 2009. Major professor: Taufik, Ph.D. "Presented to the faculty of the College of Engineering, California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "June 11, 2009." Includes bibliographical references (p. 58-59). Will also be available on microfiche.

Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gregory Durgin; Committee Member: Andrew Peterson; Committee Member: Bernard Kippelen.

Thesis (M.S.)--California Polytechnic State University, 2010. / Title from PDF title page; viewed on May 3, 2010. Major professor: Taufik, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "March 2010." Includes bibliographical references (p. 130-135).

Thesis (M.E.)--University of Canterbury, 2007. / Typescript (photocopy). "09 July 2007." Includes bibliographical references. Also available via the World Wide Web.

In this thesis, an IGBT-based DC/DC converter employing an internal inductor-capacitor-inductor (LCL) passive circuit is investigated in DC grid under fault conditions. It is concluded that a range of converter parameters exist which will give DC fault current magnitudes close to rated currents. Steady state and transient fault responses are investigated in depth. The converter is modelled on PSCAD platform under fault operation and the simulation results verify the analytical studies. LCL DC hub is an extension of DC/DC converter to multiple ports with capability of limiting the propagation of DC faults in a DC grid. Analytical mathematical equations for steady state fault currents are derived. A state space model of the hub is introduced for transient fault study. The hub is able to interconnect multiple DC cables at different voltage levels and act as DC substation for DC grid. The designed hub also has the ability to maintain the current within the order of its rated value without additional protection even for the worst case fault. The analytical study results are confirmed by detailed simulation on PSCAD. Based on the good performance of the LCL DC hub under DC faults, a DC grid topology with protection system employing LCL DC hub is proposed and investigated in this thesis. The advantage and feasibility of this method in DC fault protection is investigated based on the developed grid model. The DC grid protection systems are proposed and analysed in depth under several DC fault scenarios. The PSCAD simulation results under a range of DC fault scenarios on various locations are shown. These results confirm significance of the proposed DC grid protection system and advantages of this proposed topology in fault isolation.

M.Ing. / High frequency magnetic components have financial and physical advantages compared to low frequency magnetic components. Although high frequency magnetic components have been used for quite some time, the design and analysis of these components remain complicated.This can be ascribed to the effect of eddy currents and thermal constraints due to the smaller cooling area of such components. Planar magnetic components have long been preferred due to the higher manufacturing output, better quality control and the favorable flat shape of the component. Many studies have been conducted on planar magnetic components with respect to the energy storage capacity, air gap shape and placement, low permeability materials, to replace the air gaps, the placing of the conductors in the winding window, etc. The designs that are commonly used for planar magnetic components today, are the ones that are proven to work and not necessarily the ones that are optimal. In this study a thermal model is presented to ease the design of DC inductors. A lot of emphasis is placed on heat extraction resulting from losses in the embedded conductors through the core. This is an unconventional way to extract heat from the planar structure and leads to a new approach towards design planar inductor design.

The relative performance evaluation of the different alternatives of bridge topologies with zero-voltage switching is presented. A design-oriented analysis is developed to optimize implementation of the converters in terms of efficiency. Efficiency optimization requires minimizing the circulating currents which are directly proportional to the reactive energy required by the resonant tank. The comparison of the different converters is based on the reactive energy required for ZVS. The study considers resonant converters with conventional variable frequency control and with phase-shift control, and the zerovoltage- switched full-bridge PWM converter (ZVS-FB-PWM). Also, a systematic procedure to determine all possible resonant converters with two or three reactive elements is presented, and the design-oriented analysis used to classifY them according to their properties. The analysis for the resonant converters uses the fundamental approximation which is verified by comparison with the existing exact analysis for the series resonant converter (SRC), the parallel resonant converter (pRe) and the LCC resonant converter (LCC-RC). Comparison of design examples shows a superior performance for the LCC-RC, and less circulating current for the conventional variable-frequency resonant converters than for the phase-shifted control version. Experimental verification is provided for the phase-shifted resonant converters. The effect of switch capacitance on the zero-voltage switching (ZVS) of resonant converters is studied for the SRC, PRC and LCC-RC. The effect of switch capacitance is more' pronounced for low Q designs. Consequently, it is of primary importance for the LCC-RC whose optimal design requires low Q values. The results have been verified experimentally in an LCC-RC prototype. A complete analysis and design procedure are provided for the new ZVS-FB-PWM converter, including a new active clamp circuit that completely eliminates the ringing in the I rectifiers. The design procedure and design considerations have been verified with three' experimental prototypes. The comparison of the resonant converters with the ZVS-FB-PWM converter based on the reactive power required for ZVS, shows that the ZVS-FB-PWM converter is a superior alternative to resonant converters. The ZVS-FB-PWM converter always has less circulating current than the resonant converters when it is designed for a limited ZVS range. / Ph. D.

Zero- Voltage-Switching Multi-Resonant-Converter (ZVS-MRC) techniques are applied with hybrid microelectronics fabrication technologies to design and implement efficient, high-density (>50 W/in³) dc/dc converters. A low-profile high-density power stage of a 25 W dc/dc flyback ZVS-MRC is designed and built, and experimental results are shown. A high-density control circuit for a 50 W forward ZVS-MRC is designed using an integrated controller. This circuit is implemented into the high-density power stage previously designed by Tabisz and Lee to attain an overall converter power density of above 80 W/in³. A low-profile interleaved winding structure, fabricated by laminating copper-on-polyamide, for the transformer in the 50 W ZVS-MRC is introduced. Finite element analysis is performed to show the advantages gained with this structure. / Master of Science

The nonlinear modeling and analysis of dc-dc converters in the continuous mode and discontinuous mode has been done by averaging and discrete-sampling techniques. The averaging technique is simple to use and averages the output voltage. The discrete technique is very complex and cumbersome, but accurately predicts the envelope of the output voltage. A new model is developed by combining the aforementioned techniques. This new model, the discrete-average model, accurately predicts the envelope of the output voltage and is easy to implement in circuit and state variable forms. The major points of this dissertation are as follows: 1. The proposed model is shown to be dependent on the type of duty cycle control. 2. The proper selection of the power stage model, between average and discrete-average, is largely a function of the error processor in the feedback loop. 3. The accuracy of the measurement data taken by a conventional technique is affected by the conditions at which the data is collected. / Ph. D.