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Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 134-137).

D.Ing. (Electrical and Electronic Engineering) / The non-linear resonant pole (NLRP) inverter is part of the family of soft switching topologies based on resonant phenomena. The sequence of commutation that occurs between the semiconductors of a conventional voltage source inverter is modified through the mechanisms of energy exchange between added passive energy storage components. The NLRP inverter, through its psuedo resonant behaviour (resonant transition), gives rise to zero voltage and zero current turn-on of the switching devices as well as soft turn-off. The switching device voltage stresses are around 1 p.u, while the current stresses are reduced to around 1.3 p.u, by feeding back a portion of the load current. The rms current flowing through the inductor and switches is greatly reduced by driving the inductor into saturation (non-linear mode of operation). The advantages of soft switching, such as high switching frequency which allows greater dynamic response and higher power densities, along with reduced EMI, are achieved with this topology. Detailed analysis at multi- and sub-cycle levels is carried out, resulting in circuit equations and the criteria for commutation success. The commutation boundaries of the inverter are defined and methods discussed on how to extend them. The modulation of the NLRP inverter and some aspects regarding its use as part of both low and high performance induction motor drives are presented.

Access to sustainable energy in the developing world has become a fundamental challenge in development and environmental policy in the 21st Century, and rural electrification in developing countries constitutes a central element of access to energy goals. However, traditional ways of providing electricity to dispersed rural populations (i.e. through centralised electricity infrastructure or fuel-based on-site generation) is proving to be ineffective, inefficient and less sustainable than the use of renewable energy technologies (RETs) in off-grid settings. Such ‘system innovations' for sustainable electricity services in rural areas are the focus of this study, which seeks to understand the reasons underlying success or failure in the diffusion of radical innovations. Embracing evolutionary and constructivist theories of socio-technical change and sustainability transitions, the thesis attempts to explain the use and diffusion of PV (photovoltaic) and wind technology in off-grid rural electrification over the last 20 years in Chile, a country where access to rural electricity has increased from 53% to 95%. RETs have contributed to nearly 10% of that increment. By using a framework that combines Strategic Niche Management (SNM), systemic intermediation and power, agency and conflicts in decision making, the thesis analyses the dynamics between the development and adaptation of new technologies and their influence in regime shift through replication, scaling up and translation of new socio-technical practices. The thesis attempts to shed light on processes affecting niche construction and it concludes that internal niche processes are relevant to understanding how radical innovations are structured and stabilised from the aggregation of projects. However, those processes are not only a managerial activity that can be steered but a politically underpinned (and iterative) process between specific (socio-political) settings. The study also highlights the role of systemic intermediaries, government and incumbent actors in the dynamic interaction between emergent niche dynamics and traditional ways of improving electricity access.

With the rapid increase of the world energy demand and consumption, the method and techniques to analyze, improve and optimize energy conversion systems have to deal not only with direct fuel exergy (energy) consumption, but also with other resources, which have associated exergy consumptions, and with environmental impacts, such as global warming. A general method for energy conversion system analysis is presented in this thesis. This method uses exergy as a measure to compare and analyze the natural resource consumption (both fuels and materials) and the global warming impact of different energy conversion systems for their life-time. The method, which adds the fuel production exergy and material exergy into consideration, allows more complete exergy analyses to be conducted. The global warming impact due to the chemical emissions and impact associated with direct exergy consumption (fuel consumption) as well as system equipment materials consumption of the energy conversion system are considered together in this thesis. Based on the concept of exergy, the Total Equivalent Resource Exergy (TERE), which includes both direct resource exergy consumption and resource exergy needed to recover the total equivalent global warming gases of the energy conversion system, is proposed in this thesis. TERE uses exergy as a criterion to compare the energy conversion systems and providing information of how effective a system is regarding the use of natural resources. The calculation of TERE values for the selected energy conversion systems indicates that the resource exergy and the environmental impact exergy are both substantial impacts and should be compared together. This concept of TERE can be used as the objective function for energy system design and optimization. / Graduation date: 1996

The Department of Energy (DOE) Nuclear Energy Research Initiative (NERI) Direct Energy Conversion project has identified the fission fragment magnetic collimator reactor (FFMCR) as a promising direct fission fragment conversion concept. The US DOE NERI Proof-of-Principle Project at Texas A&M is focused on experimental verification of FFMCR operation principles. The purpose of this experiment was to test design parameters of a scaled prototype of a direct energy collector chamber of the FFMCR. The charge collection efficiency was found using a He+ ion beam to be approximately 88% for beam energies ranging from 20 to 80 keV. The 2.4 10^12 ± 10% ohm resistor used in the experiment holds-up under the stress of high voltage to 40 kV. Electric current leakage tests of the charge collection device also indicate that Teflon® is quite sufficient as an insulator for potentials as high as 40 kV. It is suggested that the present work be extended to determine power efficiencies and to achieve results with higher beam energies.

No description available.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 11, 2007) Includes bibliographical references.

Thesis submitted in partial fulfilment of the requirements for the degree Magister Technologiae: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2008 / Fuel cell technology is an emerging technology that provides a highly efficient, quiet operation, reliable, and environmentally friendly energy conversion system for stationary, automobile (vehicle), and portable applications. An electrochemical process combines hydrogen fuel and oxygen from air to produce water, and in the process it produces electricity and heat. Fuel cell stationary applications which include residential, office buildings, hospitals, hotels, airports and others have received greater attention for their ability to utilize the heat generated for space and water heating. This combined heat and power (CHP) process increases the energy conversion efficiency greatly which in turn save cost of energy usage. Different power converter topologies for fuel cell systems residential applications are presented in this thesis for efficiency, cost, component count, input ripple current minimization technique, reliability for comparison analysis. The commercial feasibility of fuel cells rests on the cost of the fuel cell system and operating efficiency and fuel cost. The proposed power converter topology consists of two front end DC-DC converters. The first front-end DC-Dc converter is tightly controlled while the second is a full bridge four interleaved DC-DC converters. Advantages of the proposed topology are reduced input ripple current, high efficiency, low maintenance cost, smaller size, modularity, redundancy. Design overview as well as simulation results are presented. Fuel cell simulation test results, including transient response are displayed and analyzed. The concept of interleaving of multiple units of the De-De converter is proposed. Interleaving enables paralleling multiple units of the converters to achieve a high combined power. This results in using semiconductor power devices of lower current rating, lowering sizes of input and output capacitors and reducing the output ripples. Simulations results are presented that verify the concept of interleaving. Preliminary work to implement interleaving is presented, and future work is recommended.

M.Ing. (Electrical Engineering Science) / One of the challenges of modern technology is remote control in real-time. Wireless technologies are used to control solar systems connected or not connected to the grid. Nevertheless wireless communications present some defects when they are facing basements of buildings and thick walls. To overcome that weakness, wire technologies seem to be the solution. The use of power line communications (PLC) technology presents a financial advantage, given the fact that PLC uses power wire to transmit data. PLC did an interesting leap forward in the last few years, and this drives researchers to carry out research in that field of Electrical Engineering. The advantages offered by PLC cannot be over-emphasized, but neither should the inherent problems affecting its commercial take-off be underestimated. This work creates a background study for experimental measurement and eventual implementations on PLC. A 2FSK modulation was implemented at CENELEC B standards, and the carrier signal was sent through a low wattage solar microinverter. The inverter was built in compliance with the IEEE 1547 standard. Two different coupling circuits were also built as well as the transceiver. The entire system was fed by a 250 W- 18 V monocrystalline solar panel. This investigation presents many options to integrate a communication system in a solar system. The case study has shown that a message sent through an H-bridge inverter is related to many parameters such as the modulation scheme, the coding techniques, the type of control and the DC link voltage. The result presents a very weak probability, which implies that the other options should be investigated.