Osciladores de ultra-baixa-tensão com aplicação em circuitos de captação de energia

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2014Abstract: This thesis describes the analysis and design of oscillators and charge pumps that can operate with very low supply voltages. The focus is on operation of the MOS transistor in the triode region owing to the limited voltage options available. Special attention has been given to the properties of the zero-VT transistor due to its high drive capability at low voltage. In order to investigate the minimum supply voltage for MOSFET oscillators, three topologies were studied. Two of them, namely the enhanced swing ring and the enhanced swing Colpitts oscillators, can operate with supply voltages below the thermal voltage, kT =q. Simplified theoretical expressions for the minimum supply voltage, oscillation frequency and minimum transistor gain of the oscillators were derived. Measurement results obtained using prototypes built with zero-VT transistors verified the operation of the oscillators for a supply voltage as low as 30 mV and 3.5 mV with high swing amplitude for arrangements built with integrated and off-theshelfinductors, respectively. The application of the ultra-low-voltage oscillators to energy harvesting circuits was addressed in this work. In order to convert the ac signal of the oscillator into a dc signal, the popular Dickson charge pump converter was employed. Expressions for the output voltage, input resistance and power converter efficiency of the Dickson charge pump operating at ultra-low voltages were derived. Experimental results obtained with prototypes built with the enhanced swing ring oscillator and the Dickson charge pump confirmed the feasibility of obtaining a dc output equal to 1 V at current consumptions of 100 nA and 1 µA from input voltages of 10 mV and 23 mV, respectively.O presente trabalho apresenta a análise, projeto e experimentação de osciladores e conversores dc-dc elevadores operando a muito baixas tensões de alimentação. Devido aos baixos valores de tensão de alimentação de interesse deste trabalho, especial atenção foi dada à operação do transistor MOS na região triodo e às propriedades do transistor zero-VT, graças a sua alta capacidade de corrente para baixas tensões. Com o objetivo de investigar a mínima tensão de alimentação de osciladores a MOSFET, três topologias foram estudadas. Duas delas, chamadas de oscilador em anel com elevada excursão desinal e oscilador Colpitts com elevada excursão de sinal, podem trabalhar com tensões de alimentação inferiores à tensão térmica, kT /q. Expressões simplificadas para a mínima tensão de alimentação, frequência de oscilação e mínimo ganho do transistor foram derivadas para cada topologia. Resultados experimentais obtidos com protótipos implementados com transistores zero-VT comprovam a operação dos osciladores com tensões tão baixas quanto 30 mV e 3,5 mV em circuitos construídos com indutores integrados e discretos, respectivamente. A aplicação dos osciladores a circuitos de captação de energia (energy harvesting circuits) a partir de fontes de alimentação de ultra-baixa-tensão foi estudada neste trabalho. Com o propósito de converter tensões ac geradas pelos osciladores em sinais dc, o clássico conversor Dickson foi utilizado. Expressões para a tensão de saída, resistência de entrada e eficiência de conversão de potência do conversor Dickson operando a ultra-baixas-tensões foram derivadas. Resultados experimentais obtidos com protótipos construídos com o oscilador em anel com elevada excursão de sinal e com o conversor Dickson, provaram a possibilidade de se obter uma tensão dc na saída de 1 V para correntes de carga de 100 nA e 1 µA a partir de tensões de entrada de 10 mV e 23 mV, respectivamente

Architectures and circuits for low-voltage energy conversion and applications in renewable energy and power management

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 337-343).In this thesis we seek to develop smaller, less expensive, and more efficient power electronics. We also investigate emerging applications where the proper implementation of these new types of power converters can have a significant impact on the overall system performance. We have developed a new two-stage dc-dc converter architecture suitable for low-voltage CMOS power delivery. The architecture, which combines the benefits of switched-capacitor and inductor-based converters, achieves both large voltage step-down and high switching frequency, while maintaining good efficiency. We explore the benefits of a new soft-charging technique that drastically reduces the major loss mechanism in switched-capacitor converters, and we show experimental results from a 5-to-1 V, 0.8 W integrated dc-dc converter developed in 180 nm CMOS technology. The use of power electronics to increase system performance in a portable thermophotovoltaic power generator is also investigated in this thesis. We show that mechanical non-idealities in a MEMS fabricated energy conversion device can be mitigated with the help of low-voltage distributed maximum power point tracking (MPPT) dc-dc converters. As part of this work, we explore low power control and sensing architectures, and present experimental results of a 300 mW integrated MPPT developed in 0.35 um CMOS with all power, sensing and control circuitry on chip. The final piece of this thesis investigates the implementation of distributed power electronics in solar photovoltaic applications. We explore the benefits of small, intelligent power converters integrated directly into the solar panel junction box to enhance overall energy capture in real-world scenarios. To this end, we developed a low-cost, high efficiency (>98%) power converter that enables intelligent control and energy conversion at the sub-panel level. Experimental field measurements show that the solution can provide up to a 35% increase in panel output power during partial shading conditions compared to current state-of-the-art solutions.by Robert C. N. Pilawa-Podgurski.Ph.D

Energy Harvesting and Energy Storage Systems

This book discuss the recent developments in energy harvesting and energy storage systems. Sustainable development systems are based on three pillars: economic development, environmental stewardship, and social equity. One of the guiding principles for finding the balance between these pillars is to limit the use of non-renewable energy sources

Analysis, modeling and design of energy management and multisource power systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 581-596).Transformative impacts on our energy security rely on creative approaches for consumption and generation of electricity. Technological contributions can impact both areas if they focus on problems of scale. For example, occupancy-based electrical loads (HVAC and lighting) accounted for roughly 50% of the total consumed electricity in the U.S. in 2008. Meanwhile, roughly 50% of consumed oil in the U.S. is imported. The U.S. Department of Energy has appropriately identified "sensing and measurement" as one of the "five fundamental technologies" essential for achieving energy security. Complementing reductions in consumption with increases in deployment of fossil-fuel-independent generation (solar and wind) and energy storage (batteries, capacitors and fuel cells) will yield a two-fold impact. Lofty energy security goals can be made realizable by aggressive application of inexpensive technologies for minimizing waste and by maximizing energy availability from desirable sources. Long-standing problems in energy consumption and generation can be addressed by adding degrees of freedom to sensing and power conversion systems using multiple electrical sources. This principal drove the invention of the hybrid electric vehicle, which achieves efficiency increases by combining the energy capacity of gasoline with the flexible storage capability of batteries. Similarly, fresh strategies for electrical circuit design, control, and estimation in systems with multiple electrical sources can minimize consumption, extend the useful life of storage, and improve the efficiency of generation. A solar array constitutes a grid or network of panels or cells that may best be modeled and treated as independent sources needing careful control to maximize overall power generation. A fuel cell stack, an array of sources in its own right, is best used in a hybrid arrangement with batteries or capacitors to mitigate the impact of electrical transients. Meanwhile, room lighting constitutes a network of multiple electrostatic field sources that can be particularly useful for occupancy detection. Exploiting performance benefits of multi-source electrical networks requires an increased flexibility in the analysis required to make informed design choices. This thesis addresses the added complexity with linear analytical and modeling approaches that reveal the salient features of complicated multisource systems. Examples and prototypes are presented in capacitive sensing occupancy detectors, hybrid power systems and multi-panel solar arrays.by John Jacob Cooley.Ph.D

Fundamentals

Volume 1 establishes the foundations of this new field. It goes through all the steps from data collection, their summary and clustering, to different aspects of resource-aware learning, i.e., hardware, memory, energy, and communication awareness. Machine learning methods are inspected with respect to resource requirements and how to enhance scalability on diverse computing architectures ranging from embedded systems to large computing clusters

Fundamentals

Volume 1 establishes the foundations of this new field. It goes through all the steps from data collection, their summary and clustering, to different aspects of resource-aware learning, i.e., hardware, memory, energy, and communication awareness. Machine learning methods are inspected with respect to resource requirements and how to enhance scalability on diverse computing architectures ranging from embedded systems to large computing clusters

WOFEX 2021 : 19th annual workshop, Ostrava, 1th September 2021 : proceedings of papers

The workshop WOFEX 2021 (PhD workshop of Faculty of Electrical Engineer-ing and Computer Science) was held on September 1st September 2021 at the VSB – Technical University of Ostrava. The workshop offers an opportunity for students to meet and share their research experiences, to discover commonalities in research and studentship, and to foster a collaborative environment for joint problem solving. PhD students are encouraged to attend in order to ensure a broad, unconfined discussion. In that view, this workshop is intended for students and researchers of this faculty offering opportunities to meet new colleagues.Ostrav

SPATIAL TRANSFORMATION PATTERN DUE TO COMMERCIAL ACTIVITY IN KAMPONG HOUSE

ABSTRACT Kampung houses are houses in kampung area of the city. Kampung House oftenly transformed into others use as urban dynamics. One of the transfomation is related to the commercial activities addition by the house owner. It make house with full private space become into mixused house with more public spaces or completely changed into full public commercial building. This study investigate the spatial transformation pattern of the kampung houses due to their commercial activities addition. Site observations, interviews and questionnaires were performed to study the spatial transformation. This study found that in kampung houses, the spatial transformation pattern was depend on type of commercial activities and owner perceptions, and there are several steps of the spatial transformation related the commercial activity addition. Keywords: spatial transformation pattern; commercial activity; owner perception, kampung house; adaptabilit

European Union Timber Regulation Impact on International Timber Markets

The trade of illegal timber, often from illegal logging, has severe environmental, social and economic consequences. The EU’s response to this problem came with the Forest Law Enforcement, Governance and Trade (FLEGT) Action Plan, with its specific goal to end illegal logging, thereby improving sustainability of forest resources. In March 2013, an additional step was taken by implementing the EU Timber Regulation (EUTR). The EUTR requires proof of timber’s origin and legality to ensure that no illegal timber is imported into the EU. To this end the EU intends to block imports of any wood or wood product which comes from unknown sources. Certification of sustainable forest management will help EU importers minimize risk, which is an essential part of their required due diligence system. Monitoring organizations are established to assist trade associations and businesses to construct comprehensive due diligence systems. National competent authorities are designated to follow the trade of the new FLEGT-licensed timber and timber products. In the first year of the EUTR there are positive impacts, of which the most important is awareness of the disastrous situation with illegal logging, driven by exports of illegal timber. Another positive development is tropical timber exporters documenting the legality of their wood exports. Yet another positive feature is establishment of due diligence systems by EU importers. However, there are considerable problems for ensuring legal trade; for example the lack of comprehensive documentation of origin and legality. Analysis of recent trends establishes changes in the European timber trade in terms of sourcing, substitution, diversion to less-demanding countries. Short-term forecasts of market trends and changes will enable further policy assessment to achieve the objectives of improved legality in international timber markets.JRC.H.3-Forest Resources and Climat