This thesis presents a distributed power-management architecture for concentrating photovoltaic (CPV) systems. Specifically, the Δ-conversion scheme with voltage equalization is analyzed and verified for the CPV system from Morgan Solar, Inc. This architecture uses inverting buck-boost converters, denoted Δ-converters, which equalize the voltages of neighbouring CPV cells in a series-connected string of cells and improve the systems tolerance to parameter variations. The power benefits of Δ-conversion and the Δ-converter current distributions are investigated using statistical simulations. The effectiveness of Δ-conversion in the presence of randomly distributed mismatches is demonstrated, and current cascading is identified as the main design challenge. The Δ-converter is modelled and compensated using Middlebrook's Extra Element Theorem. Analysis of measured data from a six-cell CPV system demonstrate the benefits of Δ-conversion under realistic scenarios. Experimental results from prototype systems show up to 31% power benefits in the presence of mismatches.

Energy-efficient radio frequency (RF) power amplifiers (PAs) are critical and paramount to achieve longer battery life in state-of-the-art portable systems because they typically determine and dominate the power consumption of such devices. In this dissertation, a high-efficiency, linear RF PA with a dynamically adaptive supply and bias current control for code division multiple access (CDMA) and wideband CDMA (WCDMA) is conceived, simulated, and experimentally demonstrated with a discrete PCB-level design and in integrated circuit (IC) form. The PA efficiency is improved by dynamically adjusting both its supply voltage and bias current, there by minimizing its quiescent power dissipation. The PA supply voltage is derived from the battery by a noninverting, synchronous buck-boost switching regulator because of its flexible functionality and high efficiency. Adjusting the PA supply voltage and bias current by tracking the output power, instead of following the complete envelope in large baseband bandwidth wireless applications, is achieved by a converter with a lower switching frequency and consequently higher light-load efficiency, which translates to prolonged battery life. A discrete PCB-level prototype of the proposed system with 915 MHz center frequency, CDMA IS-95 signal having 27-dBm peak-output power resulted in more than four times improvement in the average efficiency compared to a fixed-supply class-AB PA while meeting the required performance specifications. In the IC solution fabricated in AMIs 0.5-micron CMOS process through MOSIS, a dual-mode, buck-boost converter with pulse-width modulation (PWM) control for high power and pulse-frequency modulation (PFM) for low power is designed and implemented to improve the PA efficiency during active and standby operation, respectively. The performance of the dynamically adaptive supply and bias control IC was validated by realizing a 25-dBm, 1.96 GHz center frequency, WCDMA PA over an input supply range of 1.4 4.2 V. The PA with dual-mode power supply and bias control IC showed an average-efficiency improvement of seven times compared to a fixed-supply class-AB PA, which translates to five times improvement in battery life assuming the PA is active for 2 % of the total time and in standby mode otherwise.

For many years batteries have been used as the main power sources for portable electronic devices. However, the rate of scaling in integrated circuits and micro-electro-mechanical systems (MEMS) has been much higher than that of the batteries technology. Therefore, a need to replace these temporary energy reservoirs with small sized continuously charged energy supply units has emerged. These units, named as energy harvesters, use several types of ambient energy sources such as heat, light, and vibration to provide energy to intelligent systems such as sensor nodes. Among the available types, vibration based electromagnetic (EM) energy harvesters are particularly interesting because of their simple structure and suitability for operation at low frequency values (&lt / 10 Hz), where most vibrations exits. However, since the generated EM power and voltage is relatively low at low frequencies, high performance interface electronics is required for efficiently transferring the generated power from the harvester to the load to be supplied. The aim of this study is to design low power and efficient interface electronics to convert the low voltage and low power generated signals of the EM energy harvesters to DC to be usable by a real application. The most critical part of such interface electronics is the AC/DC converter, since all the other blocks such as DC/DC converters, power managements units, etc. rely on the rectified voltage generated by this block. Due to this, several state-of-the-art rectifier structures suitable for energy harvesting applications have been studied. Most of the previously proposed rectifiers have low conversion efficiency due to the high voltage drop across the utilized diodes. In this study, two rectifier structures are proposed: one is a new passive rectifier using the Boot Strapping technique for reducing the diode turn-on voltage values / the other structure is a comparator-based ultra low power active rectifier. The proposed structures and some of the previously reported designs have been implemented in X-FAB 0.35 &micro / m standard CMOS process. The autonomous energy harvesting systems are then realized by integrating the developed ASICs and the previously proposed EM energy harvester modules developed in our research group, and these systems have been characterized under different electromechanical excitation conditions. In this thesis, five different systems utilizing different circuits and energy harvesting modules have been presented. Among these, the system utilizing the novel Boot Strap Rectifier is implemented within a volume of 21 cm3, and delivers 1.6 V, 80 &micro / A (128 &micro / W) DC power to a load at a vibration frequency of only 2 Hz and 72 mg peak acceleration. The maximum overall power density of the system operating at 2 Hz is 6.1 &micro / W/cm3, which is the highest reported value in the literature at this operation frequency. Also, the operation of a commercially available temperature sensor using the provided power of the energy harvester has been shown. Another system utilizing the comparator-based active rectifier implemented with a volume of 16 cm3, has a dual rail output and is able to drive a 1.46 V, 37 &micro / A load with a maximum power density of 6.03 &micro / W/cm3, operating at 8 Hz. Furthermore, a signal conditioning system for EM energy harvesting has also been designed and simulated in TSMC 90 nm CMOS process. The proposed ASIC includes a highly efficient AC-DC converter as well as a power processing unit which steps up and regulates the converted DC voltages using an on-chip DC/DC converter and a sub-threshold voltage regulator with an ultra low power management unit. The total power consumption on the totally passive IC is less than 5 &micro / W, which makes it suitable for next generation MEMS-based EM energy harvesters. In the frame of this study, high efficiency CMOS rectifier ICs have been designed and tested together with several vibration based EM energy harvester modules. The results show that the best efficiency and power density values have been achieved with the proposed energy harvesting systems, within the low frequency range, to the best of our knowledge. It is also shown that further improvement of the results is possible with the utilization of a more advanced CMOS technology.

<p>The introduction of hybrid powertrains has made it possible to utilise unconventional engines as primary power units in vehicles. The free-piston energy converter (FPEC) is such an engine. It is a combination of a free-piston combustion engine and a linear electrical machine. The main features of this configuration are high efficiency and a rapid transient response.</p><p>In this thesis the free-piston energy converter as part of a hybrid powertrain is studied. One issue of the FPEC is the generation of pulsating power due to the reciprocating motion of the translator. These pulsations affect the components in the powertrain. However, it is shown that these pulsations can be handled by a normal sized DC-link capacitor bank. In addition, two approaches to reduce these pulsations are suggested: the first approach is using generator force control and the second approach is based on phase-shifted operation of two FPEC units. The latter approach results in higher frequency and lower amplitude of the pulsations, which reduce the capacitor losses.</p><p>The FPEC start-up requirements are analysed and by choosing the correct amplitude of the generator force during start-up the energy consumption can be minimised.</p><p>The performance gain of utilising the FPEC in a medium sized series hybrid electric vehicle (SHEV) is also studied. An FPEC model suitable for vehicle simulation is developed and a series hybrid powertrain, with the same performance as the Toyota Prius, is dimensioned and modelled.</p><p>Optimisation is utilised to find a lower limit on the SHEV's fuel consumption for a given drivecycle. In addition, three power management control strategies for the FPEC system are investigated: two load-following strategies using one and two FPEC units respectively and one strategy based on the ideas of an equivalent consumption minimisation (ECM) proposed earlier in the literature.</p><p>The results show a significant decrease in fuel consumption, compared to a diesel-generator powered SHEV, just by replacing the diesel-generator with an FPEC. This result is improved even more by using two FPEC units to generate the propulsion power, as this increases the efficiency at low loads. The ECM control strategy does not reduce the fuel consumption compared to the load-following strategies but gives a better utilisation of the available power sources.</p>

This thesis presents a domain-independent approach to dynamic system management using goals and policies. A goal is a general, high-level aim a system must continually work toward achieving. A policy is a statement of how a system should behave for a given set of detectable events and conditions. Combined, goals may be realised through the selection and execution of policies that contribute to their aims. In this manner, a system may be managed using a goal-directed, policy-based approach. The approach is a collection of related techniques and tools: a policy language and policy system, goal definition and refinement via policy selection, and conflict filtering among policies. Central to these themes, ontologies are used to model application domains, and incorporate domain knowledge within the system. The ACCENT policy system (Advanced Component Control Enhancing Network Technologies, http://www.cs.stir.ac.uk/accent) is used as a base for the approach, while goals and policies are defined using an extension of APPEL (Adaptable and Programmable Policy Environment and Language, http://www.cs.stir.ac.uk/appel). The approach differs from existing work in that it reduces system state, goals and policies to a numerical rather than logical form. This is more user-friendly as the goal domain may be expressed without any knowledge of formal methods. All developed techniques and tools are entirely domain-independent, allowing for reuse with other event-driven systems. The ability to express a system aim as a goal provides more powerful and proactive high-level management than was previously possible using policies alone. The approach is demonstrated and evaluated within this thesis for the domains of Internet telephony and sensor network/wind turbine management.

The software that operates mobile and embedded devices, the embedded operating system, has evolved to adapt from the traditional desktop environment, where processing horsepower and energy supply are abundant, to the challenging resource-starved embedded environment. The embedded environment presents the software with some difficult constraints when compared to the typical desktop environment: slower hardware, smaller memory size, and a limited battery life. Different embedded OSs tackle these constraints in different ways. We survey two of the more popular embedded OSs: Linux and Windows CE. To reveal their strengths and weaknesses, we examine and compare each of the OS’s process management and scheduler, interrupt handling, memory management, synchronization mechanisms and interprocess communication, and power management. / text

資訊科技的進步與智慧型手機的普及，使得人們通訊方式改變，生活也更加依賴智慧型手機。然而，電池技術卻未能支援智慧型手機長時間使用，因此手機使用者在電量管理上的行為就變得相對重要。欲研究探討手機使用者的電量管理行為模式，須建立一個包含軟、硬體及使用者的實驗平台，本研究採用經麻省理工學院驗證的Funf Framework開放性原始碼框架，作為蒐集使用者操作紀錄資料，以情境假設觀察這些資料，定義出各情境行為模式的特徵，並根據實驗數據進行所有資料驗證。根據實驗結果，大致歸納出電量管理行為模式，此結果可提供使用者使用手機在電量管理上參考，或發展智慧型電量管理應用程式，以最佳化電量管理。 / The innovation of information technology and the spread of smart phones are changing the way that people communicate and how their livings rely on smart-phones. However, the technology of battery nowadays is still insufficient to meet the need of heavy smart-phones users; therefore, it be-comes relatively important to observe and analyze the user behavior on power management. This research aims to study the patterns of user be-havior on power management by building an experimental platform with appropriate software, hardware and users. We use the Funf Open Sensing Framework, which is originally developed at the MIT Media Lab, to collect user logs on smart phones. We have observed collected data under contex-tual assumptions, identified characteristics within the context of each be-havior pattern, and validated with the experimental data. With the result of the experiment, several patterns of power management have been classified. The experimental result can be used as a reference for the users to manage battery life, or for developing applications on smart power management that best optimizes energy consumption.

Wireless and Mobile (WAM) networks have been evolving and extending their reach to more aspects of human activity for years. As such, networks have been deployed in wider and broader physical range and circumstances, so that end-to-end contemporaneous connectivity is no longer guaranteed. To address this connectivity challenge, recent research work on Disruption Tolerant Network (DTN) paradigm uses intermediate nodes to store data while waiting for transfer opportunities towards the destination. However, this work differs from conventional research work in WAM, e.g., Mobile Ad hoc Network (MANET) routing, since the connectivity assumptions are so different. In this thesis, we present the WAM Continuum framework which aims to provide a unified treatment of wireless and mobile networks. The framework is based on the construction of a WAM continuum that defines the space of networks and a corresponding formalism by which one can group related WAMs into classes that map into design and operational regimes. We show a specific instantiation of this framework that classifies networks according to their path properties and apply it to networks described by traces from both real platforms and synthesized mobility models. Effect of introducing controllable node mobility, e.g., message ferrying, is quantitatively evaluated in our study. We extend this framework in a manner that enables the classification of a WAM's energy "sufficiency" depending on a combination of the network connectivity properties, available energy, and power management scheme. As another extension under the same WAM continuum framework, this thesis studies the interaction of mobile computation collaboration and underlying network connectivity characteristics. Classification results from our framework indicate that heterogeneous connectivity may exist in WAM networks. In such cases, protocols from different routing paradigms need to work together to provide effective data communication. We focus on integration of MANET routing and message ferrying in clustered DTNs. A hybrid routing approach is developed in which both MANET routing and message ferrying are used to explore available connectivity in clusters via gateway nodes. Different data aggregation as well as transmission scheduling algorithms are proposed. To achieve better performance, we also study the ferry route design problem in the clustered DTNs and develop three route design algorithms. This thesis work also includes our experience to address challenges associated with new data communication requirements in oil field operations at remote areas. Backed up by a comprehensive measurement study of long range data links provided by satellite and cellular services, we develop a WAM network where multiple data links are jointly used to achieve an effective data communication solution in the challenged environment.

This thesis presents a distributed power-management architecture for concentrating photovoltaic (CPV) systems. Specifically, the Δ-conversion scheme with voltage equalization is analyzed and verified for the CPV system from Morgan Solar, Inc. This architecture uses inverting buck-boost converters, denoted Δ-converters, which equalize the voltages of neighbouring CPV cells in a series-connected string of cells and improve the systems tolerance to parameter variations. The power benefits of Δ-conversion and the Δ-converter current distributions are investigated using statistical simulations. The effectiveness of Δ-conversion in the presence of randomly distributed mismatches is demonstrated, and current cascading is identified as the main design challenge. The Δ-converter is modelled and compensated using Middlebrook's Extra Element Theorem. Analysis of measured data from a six-cell CPV system demonstrate the benefits of Δ-conversion under realistic scenarios. Experimental results from prototype systems show up to 31% power benefits in the presence of mismatches.

Submitted by ALEXANDRE TELES DE CASTRO null (axandre1@hotmail.com) on 2016-05-12T03:47:57Z No. of bitstreams: 1 Dissertação Alexandre_27_04_2016_Versão FINAL.docx: 2706941 bytes, checksum: 571c1689b57b8c4f5187e8c13a74c86b (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-05-12T18:31:09Z (GMT) No. of bitstreams: 1 castro_at_me_guara.pdf: 2054530 bytes, checksum: 9738a869d771260980ea50f64ba32192 (MD5) / Made available in DSpace on 2016-05-12T18:31:09Z (GMT). No. of bitstreams: 1 castro_at_me_guara.pdf: 2054530 bytes, checksum: 9738a869d771260980ea50f64ba32192 (MD5) Previous issue date: 2016-03-04 / Este trabalho visa analisar a energia elétrica das instalações elétricas, os consumos de energia elétrica, ar comprimido e água gelada, criação de novos indicadores de desempenho energético e uso de ferramentas estatísticas em uma empresa montadora de veículos. Seu principal objetivo é obter novos indicadores de desempenho energético, redução do consumo de energia elétrica em uma pesquisa ação, com a necessidade de encontrar reduções de consumo de energia nas áreas das utilidades, água gelada, água quente, ar comprimido, energia elétrica nas áreas transversais. Dentre os insumos utilizados pelas indústrias, a energia elétrica insere-se como recurso essencial em quase todas as atividades de um sistema produtivo. Dessa forma, são evidenciados os consumos de maior relevância nas áreas de utilidades e nas áreas transversais. O investimento no uso eficiente de energia elétrica traz uma série de benefícios para a empresa, para o país e para seu cliente final. Dentre os aspectos econômicos envolvidos na atividade de racionalização do uso de energia, deve-se destacar a valorização da imagem e da visão estratégica da empresa. São evidenciados os novos indicadores de desempenho energético nos setores transversais e nas utilidades, mensais. Não houve correlação dos consumos de energia elétrica entre os prédios. As tendências de consumo de ar comprimido e água gelada mostraram uma incompatibilidade, observado nos gráficos de correlação. / This work aims to analyze the demand for electric energy, electric energy consumption, compressed air and chilled water, creating new indicators of energy performance and use of statistical tools in a vehicle assembly company. Its main objective is to obtain new indicators of energy performance, reduced power consumption in an action research, with the need for energy consumption reductions in the areas of utilities, cold water, hot water, compressed air, chilled water, energy electric in cross-cutting areas. Among the inputs used by industries, the electricity is part of an essential feature in almost all activities of a production system. Thus, it is highlighted the most relevant consumption in the areas of utilities and in cross-cutting areas. Investment in energy-efficient brings a number of benefits for the company, for the country and for your end customer. Among the economic aspects involved in rationalizing activity of energy use, it should be noted to enhance the image and the strategic vision of the company. It will be shown the new energy performance indicators in cross-cutting sectors and the utilities, monthly. There was no correlation of electric energy consumption between buildings. The compressed air consumption trends and chilled water showed a mismatch, seen in correlation graphs.