The miniaturization of dc–dc switch-mode power supplies (SMPS) is of a key importance in volume-sensitive portable devices, such as cell phones, tablet computers, and digital cameras. In these systems, multiple SMPS are required to provide well regulated voltage and power to various electronic components such as the central processing unit (CPU) and random-access memory (RAM). The combined volume, weight, and surface area footprint of these SMPS is usually the largest component. Traditionally, SMPS volume reduction has been achieved through increased switching frequencies; however, for power-sensitive applications this is undesirable due to the increased switching losses. This thesis presents two alternative, power-efficient, SMPS miniaturization methods: one control and one topology based. The presented controller recovers from load transients with virtually minimum possible output voltage deviation, reducing the reactive component size. The controller utilizes a simple algorithm, requiring no knowledge of the converter parameters and virtually no processing power. The simplicity of the control concept enabled the design of an area and power efficient integrated circuit (IC) implementation. The entire IC is implemented in a CMOS 0.18µm process on a 0.26 mm2 silicon area, which is comparable to the state-of-the-art analog solutions. For the experimental system the deviation (output capacitor size) is about four times smaller than that of a fast PID compensator having a 1/10th of the switching frequency bandwidth. The second solution is a complementary converter topology that has a smaller output filter volume, improved dynamic response, and lower switching losses compared to the state-of-the-art solutions. To reduce the volume and switching losses, the input-to-output voltage difference is decreased with a capacitive attenuator that replaces the input filter capacitor and has approximately the same volume. Both the attenuator and the downstream buck converter share the same set of switches, minimizing conduction losses. A single multi-mode digital controller governs operation of both stages, seamlessly regulating the output and input center-tap voltages. Experiments with a 5–1.5-V, 2.5-A, 1-MHz prototype show that, compared to the conventional buck, the merged topology has 43% smaller inductor, 36% smaller output capacitor, up to 30% lower power losses, and a 25% faster transient response.

The miniaturization of dc–dc switch-mode power supplies (SMPS) is of a key importance in volume-sensitive portable devices, such as cell phones, tablet computers, and digital cameras. In these systems, multiple SMPS are required to provide well regulated voltage and power to various electronic components such as the central processing unit (CPU) and random-access memory (RAM). The combined volume, weight, and surface area footprint of these SMPS is usually the largest component. Traditionally, SMPS volume reduction has been achieved through increased switching frequencies; however, for power-sensitive applications this is undesirable due to the increased switching losses. This thesis presents two alternative, power-efficient, SMPS miniaturization methods: one control and one topology based. The presented controller recovers from load transients with virtually minimum possible output voltage deviation, reducing the reactive component size. The controller utilizes a simple algorithm, requiring no knowledge of the converter parameters and virtually no processing power. The simplicity of the control concept enabled the design of an area and power efficient integrated circuit (IC) implementation. The entire IC is implemented in a CMOS 0.18µm process on a 0.26 mm2 silicon area, which is comparable to the state-of-the-art analog solutions. For the experimental system the deviation (output capacitor size) is about four times smaller than that of a fast PID compensator having a 1/10th of the switching frequency bandwidth. The second solution is a complementary converter topology that has a smaller output filter volume, improved dynamic response, and lower switching losses compared to the state-of-the-art solutions. To reduce the volume and switching losses, the input-to-output voltage difference is decreased with a capacitive attenuator that replaces the input filter capacitor and has approximately the same volume. Both the attenuator and the downstream buck converter share the same set of switches, minimizing conduction losses. A single multi-mode digital controller governs operation of both stages, seamlessly regulating the output and input center-tap voltages. Experiments with a 5–1.5-V, 2.5-A, 1-MHz prototype show that, compared to the conventional buck, the merged topology has 43% smaller inductor, 36% smaller output capacitor, up to 30% lower power losses, and a 25% faster transient response.

The goal of this dissertation is to evaluate the effectiveness of model predictive control (MPC) for a magnetically suspended flywheel energy storage uninterruptible power supply (FlyUPS). The reason this research topic was selected was to determine if an advanced control technique such as MPC could perform better than a classical control approach such as decentralised Proportional-plus-Differential (PD) control. Based on a literature study of the FlyUPS system and the MPC strategies available, two MPC strategies were used to design two possible MPC controllers were designed for the FlyUPS, namely a classical MPC algorithm that incorporates optimisation techniques and the MPC algorithm used in the MATLAB® MPC toolbox™. In order to take the restrictions of the system into consideration, the model used to derive the controllers was reduced to an order of ten according to the Hankel singular value decomposition of the model. Simulation results indicated that the first controller based on a classical MPC algorithm and optimisation techniques was not verified as a viable control strategy to be implemented on the physical FlyUPS system due to difficulties obtaining the desired response. The second controller derived using the MATLAB® MPC toolbox™ was verified to be a viable control strategy for the FlyUPS by delivering good performance in simulation. The verified MPC controller was then implemented on the FlyUPS. This implementation was then analysed in order to validate that the controller operates as expected through a comparison of the simulation and implementation results. Further analysis was then done by comparing the performance of MPC with decentralised PD control in order to determine the advantages and limitations of using MPC on the FlyUPS. The advantages indicated by the evaluation include the simplicity of the design of the controller that follows directly from the specifications of the system and the dynamics of the system, and the good performance of the controller within the parameters of the controller design. The limitations identified during this evaluation include the high computational load that requires a relatively long execution time, and the inability of the MPC controller to adapt to unmodelled system dynamics. Based on this evaluation MPC can be seen as a viable control strategy for the FlyUPS, however more research is needed to optimise the MPC approach to yield significant advantages over other control techniques such as decentralised PD control. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013

The objective of this dissertation is to derive a set of compact physical models addressing power integrity issues in high performance gigascale integration (GSI) systems and three-dimensional (3-D) systems. The aggressive scaling of CMOS integrated circuits makes the design of power distribution networks a serious challenge. This is because the supply current and clock frequency are increasing, which increases the power supply noise. The scaling of the supply voltage slowed down in recent years, but the logic on the integrated circuit (IC) still becomes more sensitive to any supply voltage change because of the decreasing clock cycle and therefore noise margin. Excessive power supply noise can lead to severe degradation of chip performance and even logic failure. Therefore, power supply noise modeling and power integrity validation are of great significance in GSI systems and 3-D systems. Compact physical models enable quick recognition of the power supply noise without doing dedicated simulations. In this dissertation, accurate and compact physical models for the power supply noise are derived for power hungry blocks, hot spots, 3-D chip stacks, and chip/package co-design. The impacts of noise on transmission line performance are also investigated using compact physical modeling schemes. The models can help designers gain sufficient physical insights into the complicated power delivery system and tradeoff various important chip and package design parameters during the early stages of design. The models are compared with commercial tools and display high accuracy.

Thesis (M.S.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Kungälv Energi äger och ansvarar idag över Kungälv Kommuns elnät. Med en ökande befolkningsmängd ställs allt högre krav på elnätet och framför allt leveranssäkerheten. Med kalla vintrar och stort energibehov ger detta upphov till en svårare situation gällande leveranssäkerhet. I nuläget har Kungälv Energi två mottagarstationer, en 130/10kV-station espektive 130/20kV-station. 30/10kV-stationen börjar närma sig en gräns där effektbehovet närmar sig den maximala istributionskapaciteten. Därför fastställs en plan för att kunna klara av effektbehovet vid averi på en av två 130/10kV-transformatorer i mottagarstationen M1. Resultatet av rapporten visar att tillräcklig kapacitet finns i närliggande fördelningsstationer för att klara av reservdrift under hög belastning utan att några övriga komponenter skadas. Rapporten behandlar främst effektflöden för att kontrollera att dessa ej överskrider transformatorernas, ledningarnas och kablarnas märkeffekt. I flertalet fall har även faktorer för nödbelastning räknats med vilket resulterar i att samtliga linjer hos Kungälv Energi klarar av den ökade belastningen. Upptäckta flaskhalsar i nätet har uppmärksammats och delgetts samt förslag till förändringar för att förhindra framtida problem. / Kungälv Energi owns and is responsible of Kungälv municipality's electricity grid. With an increasing population and increasing demands on the grid and especially security of supply. With cold winters and large energy gives rise to a more difficult situation regarding security of supply. Currently, Kungälv Energi two receiving stations, a 130 / 10kV station and 130 / 20kV station. 130 / 10kV station is approaching a point where power demand is approaching the maximum distribution capacity. Therefore sets out a plan to cope with the power demand at the failure of one of two 130 / 10kV transformers of the receiving station M1. The results of the report shows that sufficient capacity is available in nearby distribution stations to cope with the emergency operation under high loads without any other components damaged. The report deals primarily with power flows to check that they do not exceed transformers, lines and cables rated power. In the majority of cases have also factors for distress load been counted with, which gives the result that all lines of Kungälv Energi can handle the increased load. Detected bottlenecks in the network have been highlighted, communicated and proposed changes to Kungälv Energi to prevent future problems.

Thesis (MPhil)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Amid the climate change crisis of the 21st century, South Africa faces its own, tailor-made challenges. In its attempt to contribute to the global effort to mitigate climate change and achieve sustainable development, South Africa faces the challenge of a history steeped in cheap electricity - the curse of an abundance of coal. The municipality, as the lowest leg of governance, currently finds itself at a tough nexus, involving; municipal mandates to provide basic services; the possible financial risks of implementing RETs; the regulatory ambiguity surrounding electricity generation and distribution jurisdiction; and the necessary implementation of RETs as a means of addressing the growing risk of revenue loss from reduced electricity sales as consumers install their own RETs, and as a contribution to national climate change mitigation. This nexus is herein referred to as the ‘municipal dilemma’. This thesis, via a complex systems approach, explores the major barriers and policy opportunities in the implementation of renewable energy technologies (RETs) by municipalities embedded within the larger ambit of the South African government, as they attempt to address what the author has termed the ‘municipal dilemma’. What is especially interesting and relevant about a complex systems approach is the notion of learning and therefore adaptability. In light of municipalities and their role in the South African context, the notion of systems learning affords a unique perspective into the municipal dilemma and means of overcoming it. From a literature analysis of policy, through to a specific case study of Hessequa municipality, this study sought to assist municipalities in addressing this dilemma. South Africa’s energy and municipal management policies starting from the Constitution, is found to be conducive to the growth of RETs. Furthermore, there are clear channels through which municipalities can engage with these new technologies to address the municipal dilemma. What is seen to hinder this process is a web of institutional, political and regulatory barriers stemming from the over-politicization of the country’s energy sector - a direct result of a long history entrenched in coal-fired electricity generation. What was found lacking in the South African energy debate was the perspective of the municipality itself, which is ultimately tasked with catering for the energy needs of South African citizens while participating in national efforts. The notion that municipalities are best positioned to be influential in the growth of RETs is reinforced by the literature explored and through a complex systems approach. To effectively play their role, municipalities must: (a) be creative and bold in their development of appropriate policies to support RETs; (b) align their efforts with provincial and national programmes and simultaneously influence these programmes through municipal experience; (c) take advantage of systems in place, such as the Integrated Development Plan (IDP) process, to gradually build capacity within the municipality to manage increasingly complex RET implementation; (d) develop long-term strategies which, as per the tenets of complex systems theory, must feed from and into the ever-changing national and global landscape. This thesis posits that the municipal dilemma not only needs to be addressed, but offers the municipality a unique opportunity to rethink its role in the South African context. It has been found that a conducive regulatory environment is on the rise in the South African energy context. This environment, however, still requires much input from municipalities which are well positioned to offer direction to the policy creation process. In doing so, municipalities not only address the municipal dilemma, by also take their place as custodians of sustainable development. / AFRIKAANSE OPSOMMING: Te midde van die krisis van die 21ste eeu, naamlik die uitdaging van klimaatverandering, staar Suid-Afrika sy eie, unieke uitdagings in die gesig. Met die nodigheid om by te dra tot die globale poging om klimaatsverandering te versag en volhoubare ontwikkeling mee te bring, is Suid-Afrika gekonfronteer met die uitdaging van 'n geskiedenis ‘ryk’ in goedkoop elektrisiteit - die vloek van 'n oorvloed steenkool. Hierdienooreenkomstig bevind die munisipaliteit, as die laagste been van regering, homself in 'n moeilike krisispunt, naamlik die handhawing van die grondwetlike mandaat om basiese dienste te verskaf, en om ekonomiese ontwikkeling te verseker, maar tog by te dra tot die land se volhoubare ontwikkeling. Dit is uiters moeilik om alle aspekte genoegsaam aan te spreek, en hierna word verwys as die munsipale dilemma. Ter oorweging van die munisipaliteit as ingebed in 'n groter stelsel, naamlik die Suid-Afrikaanse konteks, en met 'n komplekse stelselsbenadering om die munisipale dilemma aan te spreek, ondersoek hierdie tesis die groot struikelblokke tot, en beleidsgeleenthede vir, die implementering van hernubare energietegnologie deur munisipaliteite. In terme van die komplekse stelsels benadering is veral belangrik die opvattings van leer en dus aanpasbaarheid van die stelsels en hul relevansie vir die Suid-Afrikaanse konteks. Uit 'n ontleding van die beleidsliteratuur, en deur ‘n spesifieke gevallestudie van Hessequa munisipaliteit, poog hierdie studie om munisipaliteite te help in die aanspreek van hul dilemma. Daar is gevind dat Suid-Afrika se energie- en munisipale bestuursbeleid, vanaf die Grondwet, die groei van hernubare energietegnologie bevorder. Verder is daar duidelike kanale waardeur munisipaliteite betrokke kan raak by hierdie nuwe tegnologie ten einde die munisipale dilemma aan te spreek. Hierdie proses word wel verhinder deur 'n web van institusionele, politieke en regulatoriese hindernisse, wat spruit uit die oorverpolitisering van die land se energie-sektor; 'n direkte gevolg van 'n lang geskiedenis verskans in steenkool-aangedrewe opwekking van elektrisiteit. Wat ontbreek in die Suid-Afrikaanse energie-debat is die perspektief van die munisipaliteit self, wat uiteindelik getaak is met die adressering van die behoeftes van die Suid-Afrikaanse samelewing, met gelyktydige deelname aan nasionale pogings. Die plaaslike en globale gevallestudies lig talle gemeenskaplike temas uit en vorm die basis van die gevolgtrekkings van hierdie tesis. Die idee dat munisipaliteite die beste geposisioneer is om invloedryk te wees in die groei van hernubare energietegnologie word versterk deur die literatuur ondersoek en deur middel van 'n komplekse sisteem benadering tot die gevallestudies. Om effektief te wees in hul rol, moet munisipaliteite (a) kreatief en dapper wees in hul ontwikkeling van toepaslike beleide om dié tegnologieë te ondersteun; (b) hul pogings in lyn bring met provinsiale en nasionale programme en terselfdertyd hierdie programme beïnvloed deur munisipale ervaring; (c) voordeel trek uit stelsels wat reeds in plek is om geleidelik kapasiteit op te bou binne die munisipaliteit om die toenemend komplekse hernubare energie implementering te bestuur; en (d) langtermyn strategieë ontwikkel in die steeds veranderende nasionale en internasionale landskap. Hierdie tesis postuleer dus dat die munisipale dilemma nie net aangespreek moet word nie, maar bied die munisipaliteit 'n unieke geleentheid om sy rol in die Suid-Afrikaanse konteks te heroorweeg. Wat bevind is, is dat toepaslike beleid reeds bestaan en dat munisipaliteite hul plek kan inneem as bewaarders van volhoubare ontwikkeling.

Made available in DSpace on 2014-06-11T19:27:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-12Bitstream added on 2014-06-13T19:47:35Z : No. of bitstreams: 1 ferreira_mc_me_sjrp.pdf: 2030782 bytes, checksum: 6be665234f9e1a4c6116708f4f20c11c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho realizamos um estudo de um sistema dinâmico não ideal, constituído por um pêndulo acoplado a um bloco e que oscilam verticalmente. A oscilação é devida a rotação de uma massa desbalanceada e acionada por um motor DC, cuja fonte de energia é limitada. Consideramos situações em que as freqüências do bloco e do pêndulo estão em ressonâncias internas 1:1, 1:2 e 2:1, e analisamos o comportamento do sistema bloco- motor-pêndulo através de simulações numéricas. Uma análise similar e levada a efeito, no caso em que o sistema dinâmico é dotado de uma excitação de suporte ideal horizontal do tipo F cos wt. / In this work we studied a nonideal dynamical system which is constituted by a pendulum connected to a block, and that oscillates vertically. The oscillation is due to the rotation of a unbalanced mass moved by DC motor with limited power supply. We consider situations where the frequencies of the block and the pendulum are in 1:1, 1:2 and 2:1 internal resonances, and we analyse the behavior of the block - motor - pendulum system through numerical simulations. A similar analysis is performed in the case where the dynamical system has a periodic horizontal oscillation of type F cos wt.

This thesis investigated the possibility of integrating a small photovoltaic module in a wireless sensor network node prototype made for use in crop production, mainly in greenhouses. The main question was if the simple photovoltaic module could provide enough power to the prototype's recharge system in order to continuously recharge the battery and thereby reducing the time maintaining the device due to its power consumption. Through measurements, both of the energy supplied by the potential photo voltaic modules and the prototype's power demand, the conclusion was that the power would not be sufficient due to the concealing environment in which the device would be placed. However, suggestions for further work was given in how the proposed idea could be developed.