Dissertations / Theses on the topic 'Low power excitation source'

This thesis work primarily focuses on the applicability of sub-threshold source coupled logic (STSCL) for building digital circuits and systems that run at very low voltage and promise to provide desirable performance with excellent energy savings. Sectors like bio-engineering and smart sensors require the energy consumption to be effectively very low for long battery life. Alongside meeting the ultra-low power specification, the system must also be reliable, robust, and perform well under harsh conditions. In this thesis work, logic gates are designed and analyzed, using STSCL. These gates are further used for implementation of digital subsystems in small-sized smart dust sensors which would operate at very low supply voltages and consume extremely low power. For understanding the performance of STSCL with respect to ultra-low power and energy; a seven-stage ring oscillator, a 4-by-4 array multiplier, a fifth-order FIR filter and finally a fifty-fifth-order FIR filter were designed. The subcircuits and systems have been simulated for different supply voltages, scaling down to 0.2 V, at different temperature values (-20oC and 70oC) in both 45 nm and 65 nm process technologies. The chosen architectures for the FIR filters and array multiplier were conventional and essentially taken from traditional CMOS-based designs. The simulated results are studied, analyzed and compared with same CMOS-based digital circuits. The results show on the advantage of STSCL-based digital systems over CMOS. Simulation results provide an energy consumption of 1.1388 nJ for a fifty-fifth-order FIR filter, at low temperatures (-20oC), using STSCL logic, which is comparatively less than for the corresponding CMOS logic implementation.

Aquesta tesi està enfocada en dues línies d'investigació. La primera aborda el desenvolupament d'una metodologia basada en llum polsada per modulació de sensors químic-resistius per a l'extracció d'informació del senyal transitòri, i la segona planteja la implementació d'una xarxa sense fils de sensors (WSN) basada en tecnologia LoRa per al monitoratge de la qualitat de l'aire (AQM) i la detecció d'esdeveniments de fuita de gasos. Aquest document està estructurat en quatre capítols organitzats de la següent manera: el Capítol 1 presenta l'estat de l'art, una introducció als mecanismes de millora de l'comportament dels sensors químic-resistius, així com una introducció a la implementació de xarxes sense fils de sensors per a la monitorització de la qualitat de l'aire; el Capítol 2 està compost pels dos articles publicats relacionats amb la metodologia basada en la modulació utilitzant llum polsada per a l'extracció d'informació del senyal transitòria de sensors químic-resistius; el Capítol 3 presenta l'article publicat relacionat amb la implementació d'una WSN per a AQM; el Capítol 4 presenta les conclusions derivades dels resultats obtinguts durant el desenvolupament de el projecte de tesi i les recomanacions per al treball futur associat a la continuïtat dels principals resultats d'aquesta tesi
La presente tesis está enfocada en dos líneas de investigación, La primera aborda el desarrollo de una metodología basada en luz pulsada para modulación de sensores químico-resistivos para la extracción de información de la señal transitoria; y la segunda plantea la implementación de una red inalámbrica de sensores (WSN) basada en tecnología LoRa para la monitorización de la calidad del aire (AQM) y la detección de eventos de fuga de gases. Este documento está estructurado en cuatro capítulos organizados de la siguiente forma: el Capítulo 1 presenta el estado del arte, una introducción a los mecanismos de mejora del comportamiento de los sensores químico-resistivos, así como una introducción a la implementación de redes inalámbricas de sensores para la monitorización de la calidad del aire; el Capítulo 2 está compuesto por los dos artículos publicados relacionados con la metodología basada en la modulación utilizando luz pulsada para la extracción de información de la señal transitoria de sensores químico-resistivos; el Capítulo 3 presenta el artículo publicado relacionado con la implementación de una WSN para AQM; el Capítulo 4 presenta las conclusiones derivadas de los resultados obtenidos durante el desarrollo de el proyecto de tesis y las recomendaciones para el trabajo futuro asociado a la continuidad de los principales resultados de esta tesis.
The present thesis project is focused in two different yet related research lines. The first one addresses the development of a pulsed light-based chemiresistive sensor modulation methodology for transient information extraction. The second research line developed deals with the implementation of a LoRa-based portable, scalable, low-cost, and low power Wireless Sensor Network (WSN) for Air Quality Monitoring (AQM) and gas leakage events detection. This document is structured in four Chapters organized as follows: Chapter 1 presents the state of the art, an introduction to sensing performance enhancement and transient data extraction methods, as well as an introduction to the implementation of WSN for AQM; Chapter 2 is composed of the two published paper related to the pulsed light modulation methodology for transient information extraction; Chapter 3 presents the published paper related to the implementation of a LoRa-based WSN for AQM; Chapter 4 states the conclusions derived from the results obtained during this thesis project and the recommendations for the future work associated to the continuity of this thesis findings.

This research work is devoted to the analysis, design and development of the Current-Source Converter (CSC) based distribution-type Static Synchronous Compensator (D-STATCOM) for low-voltage applications in reactive-power control in order to achieve i) faster transient response in reactive-power control, ii) lower current harmonic distortion, iii) lower power losses and iv) minimum storage elements in comparison with conventional solutions. The developed CSC-D-STATCOM includes a low-pass input filter and a three phase forced-commutated CSC which is composed of six insulated gate bipolar transistors (IGBT) with built-in series diodes. The analysis and the control of the CSC-D-STATCOM are carried out in dq-synchronous reference frame in order to obtain the reference current waveform which is to be generated by switching the IGBTs at 3kHz with the use of space vector modulation.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2017.
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Neste documento é desenvolvida uma metodologia de projeto de uma fonte de corrente auto polarizada de ultra baixo consumo de potência em tecnologia CMOS. É descrita uma topologia modular implementada com dois MOSFETs auto cascodados (SCMs) e um amplificador operacional. A metodologia proposta está baseada no conceito de ni´veis de inversão e o espaço de projeto do circuito é descrito principalmente em termos das especificações do amplificador operacional e do espelho de corrente PMOS. O circuito foi projetado usando uma tecnologia padrão CMOS de 130 nm. Os resultados das simulações são apresentados neste documento para validar a metodologia de projeto e o desempenho da fonte de corrente, mostrando que o circuito proposto pode operar com uma tensão de alimentação menor de 1 V e com menos de 1%/V na regulação de linha.

Abstract : In this document a design procedure of a CMOS ultra-low-power self-biased current source is developed. A modular topology using two self-cascode MOSFETs (SCMs), a current mirror and an operational amplifier is implemented. The described methodology is based on the concept of inversion level, and the design space of the current source is described mainly in terms of the specifications of the operational amplifier and the PMOS current mirror. The circuit was designed in a 130 nm standard CMOS technology. Simulation results are provided to validate the design methodology and the performance of the current source, showing that the proposed circuit can operate at a supply voltage less than 1 V with less than 1%/V of line regulation.

The major thrusts of this work have been: 1) To develop a high-efficiency low-power TM-010 microwave cavity for nitrogen support gas at atmospheric pressure, 2) To discover and physically characterize potential laser and emission spectroscopic applications of this atom source, with a particular emphasis on laser-induced fluorescence. The result is the most efficient microwave-induced plasma cavity for nitrogen at one atmosphere that exists to date, giving stable and analytically useful molecular plasmas with only 50 Watts applied power. It is called the “High-Efficiency Molecular Microwave Plasma" (HEMMP) cavity. The HEMMP possesses excellent vaporization and atomization properties. It can handle aqueous sample flows of around 1 mL/min, introduced as an aerosol from a nebulizer. A detection system and sampling system were designed and an analytical instrument was built around the HEMMP cavity. Details of construction, operating conditions and operation of the instrument are described. Applications investigated include laser-induced fluorescence (LIF), atomic emission spectroscopy (AES), and laser-enhanced ionization (LEI) [also known as the opto-galvanic effect (OGE)]. The major emphasis of the application work has been physical characterization of the low-power nitrogen plasma as an atom source for LIF. This is the first time that either laser-induced fluorescence or laser-enhanced ionization have been observed and extensively characterized in any microwave-induced plasma (MIP). This is also the first time that atomic emission has been studied in a low-power N₂-MIP. LIF, AES, and LEI signal intensities were studied as a function of applied microwave power, support gas flow rate, signal observation height, and support gas composition using nitrogen and argon mixtures. Results for LIF yielded detection limits in the very low parts per billion range, and for AES in the low parts per billion range. Limit of detection (LOD) and background noise studies were done for all 3 techniques. Signal intensities were measured as a function of laser light intensity for LIF and LEI. Laser saturation was not observed with 300 mW power from the CW dye laser. The effects of electrode geometry and applied electrode voltage on LEI signals were also studied. Extensive background spectral studies were done for the nitrogen plasma. Analytical feasibility has been demonstrated for AES, LIF, and LEI in the low-power nitrogen MIP. The results presented provide the background physical investigations required for a full-scale development of these techniques for chemical analysis.
Ph. D.

Inductive power transmission is very useful, not only for systems where energy transfer should take place in hazardous, humid and wet areas, but also for mobile and very small systems. It finds today a widespread use in several fields, such as industry, automotive, medicine and smart buildings. For a good efficiency and a high-power transmission, the sending and the receiving coils should be perfectly aligned and close to each other. A misalignment between the sender and the receiver becomes unavoidable especially for systems with movable parts. This thesis aims to improve the transmitted power, the mutual inductance, the power at the load, and consequently the power transmission efficiency in case of lateral misalignment between the sending and receiving coils and at large coil-to-coil distance. For this purpose, we adopt a multi input single output (MISO) coil system able to orientate the issued magnetic field to the receiving coil by powering the neighbouring sending coils of the active ones with a weak current in the opposite direction. Furthermore, an analytical model of the used coils and an accurate three-dimensional model of the system have been developed to calculate the induced voltage, the induced current, and the equivalent mutual inductance. Both simulation and experimental results prove that the proposed multi-coil inductive system having an hexagonal arrangement and the sending coils, which have the half diameter of the receiving coil, is able to improve significantly the transmitted power in case of lateral misalignment and big air gap. The novel MISO system reaches better efficiency beginning with an air gap of 50% of the sending coil diameter, and a misalignment of 28% of the sending coil diameter. It reaches the double of the transmitted power of the conventional two-coil inductive system at 50 mm air gap (corresponding to 166% of the sending coil diameter) and at 10 mm lateral misalignment (corresponding to 33% of the sending coil diameter). In order to improve the equivalent mutual inductance between the primary and secondary sides and to avoid energy losses, we propose a receiver detection method using the sending coils themselves as detectors. Thereby, only the sending coils, under the receiver, are activated and the others remain switched off. For that, the peak of the AC current of the sending coils, is measured and then compared to a detection threshold. The excitation strategy of the active sending coils is optimized corresponding to the receiving coil position. The novel excitation strategy increases the mutual inductance by 85% and the induced voltage by 13% at perfect alignment and by 30% and 10% respectively at 10 mm lateral misalignment, in comparison to the MISO system without a receiver detector and coil-excitation strategy. In order to increase the transmitted power by resonance, different system topologies have been investigated, such as series-series SS, series-parallel SP, parallel-series PS, and parallel-parallel PP topologies for different levels of load impedance. The results show that a multi-coil inductive system with parallel-parallel PP topology realizes a higher transmitted power than the other topologies for both high and low load impedance values. The proposed multi-coil inductive system is suitable for low-power systems, such as wireless sensors and biomedical implants, but can be also applied to higher range of power at a flexible position of the receiver.
Die induktive Energieübertragung ist interessant, nicht nur für Systeme, bei denen die Energieübertragung in rauen, feuchten und nassen Bereichen erfolgen soll, sondern auch für mobile und sehr kleine Systeme. Diese Art von Energieübertragung findet heute eine breite Anwendung in verschiedenen Bereichen, wie z.B. Industrie, Automobil, Medizin und intelligente Gebäude. Um eine gute Effizienz und eine hohe Energieübertragungsleistung zu realisieren, sollten die Sende- und Empfangsspulen perfekt ausgerichtet und nahe beieinander sein. Insbesondere bei Systemen mit beweglichen Teilen ist jedoch eine Fehlausrichtung zwischen Sender und Empfänger unvermeidlich. Diese Arbeit zielt darauf ab, die übertragene Leistung, die gegenseitige Induktivität, die Leistung an der Last und damit den Wirkungsgrad der Leistungsübertragung im Falle einer seitlichen Fehlausrichtung zwischen Sende- und Empfangsspule und bei großem Abstand von Spule zu Spule zu verbessern. Zu diesem Zweck wird ein Multi-Input Single-Output (MISO)-Spulensystem vorgeschlagen, das in der Lage ist, das ausgegebene Magnetfeld auf die Empfangsspule auszurichten, indem die benachbarten Spulen der aktiven Sendespulen mit einem schwachen Strom in der entgegengesetzten Richtung versorgt wird. Darüber hinaus wurde ein analytisches Modell für die verwendeten Spulen und ein genaues dreidimensionales Modell für das System entwickelt, um die induzierte Spannung, den induzierten Strom und die äquivalente gegenseitige Induktivität zu berechnen. Sowohl die Simulation als auch die experimentellen Ergebnisse belegen, dass das vorgeschlagene induktive Mehrfachspulensystem mit hexagonaler Anordnung und die Sendespulen, die den halben Durchmesser der Empfangsspule haben, in der Lage sind, die Sendeleistung bei lateraler Fehlausrichtung und großem Luftspalt deutlich zu verbessern. Das neuartige MISO-System erreicht einen besseren Wirkungsgrad, beginnend mit einem Luftspalt von 50% des Sendespulendurchmessers und einer Fehlausrichtung von 28% des Sendespulendurchmessers. Sie erreicht bei 50 mm Luftspalt (entspricht 166% des Sendespulendurchmessers) und bei 10 mm seitlichem Versatz (entspricht 33% des Sendespulendurchmessers) das Doppelte der Sendeleistung des herkömmlichen Zwei-Spulen-Induktivsystems. Um die äquivalente gegenseitige Induktivität zwischen Primär- und Sekundärseite zu verbessern und Energieverluste zu vermeiden, schlagen wir ein Verfahren zur Detektion des Empfängers vor, bei dem die Sendespulen selbst als Detektoren verwendet werden. Dabei werden nur die Sendespulen unter dem Empfänger aktiviert und die anderen bleiben ausgeschaltet. Dazu wird der Scheitelwert des Wechselstroms der Sendespulen gemessen und mit einem vorgegebenem Schwellenwert verglichen. Die Anregungsstrategie der aktiven Spulen wird entsprechend der Position der Empfangsspule optimiert. Die neuartige Anregungsstrategie erhöht die gegenseitige Induktivität um 85% und die induzierte Spannung um 13% bei perfekter Ausrichtung und um 30% bzw. 10% bei 10 mm seitlichem Versatz, im Vergleich zum MISO-System ohne Empfängerdetektor und Spulenanregungsstrategie. Um die übertragene Leistung durch Resonanz zu erhöhen, wurden verschiedene Systemtopologien untersucht, wie z.B. Serien-SS, Serien-Parallel-SP, Parallel-Series-PS und Parallel-Parallel-PP-Topologien für verschiedene Stufen der Lastimpedanz. Die Ergebnisse zeigen, dass ein MISO System mit parallel-paralleler PP-Topologie eine höhere Sendeleistung realisiert als die anderen Topologien für hohe und niedrige Last-Impedanzen. Das vorgeschlagene induktive Mehrspulensystem eignet sich für Systeme mit geringer Leistung, wie drahtlose Sensoren und biomedizinische Implantate, kann aber auch flexibler Position des Empfängers in einen höheren Leistungsbereich angewendet werden.

The ability of a piezoelectric transducer in energy conversion is rapidly expanding in several applications. Some of the industrial applications for which a high power ultrasound transducer can be used are surface cleaning, water treatment, plastic welding and food sterilization. Also, a high power ultrasound transducer plays a great role in biomedical applications such as diagnostic and therapeutic applications. An ultrasound transducer is usually applied to convert electrical energy to mechanical energy and vice versa. In some high power ultrasound system, ultrasound transducers are applied as a transmitter, as a receiver or both. As a transmitter, it converts electrical energy to mechanical energy while a receiver converts mechanical energy to electrical energy as a sensor for control system. Once a piezoelectric transducer is excited by electrical signal, piezoelectric material starts to vibrate and generates ultrasound waves. A portion of the ultrasound waves which passes through the medium will be sensed by the receiver and converted to electrical energy. To drive an ultrasound transducer, an excitation signal should be properly designed otherwise undesired signal (low quality) can deteriorate the performance of the transducer (energy conversion) and increase power consumption in the system. For instance, some portion of generated power may be delivered in unwanted frequency which is not acceptable for some applications especially for biomedical applications. To achieve better performance of the transducer, along with the quality of the excitation signal, the characteristics of the high power ultrasound transducer should be taken into consideration as well. In this regard, several simulation and experimental tests are carried out in this research to model high power ultrasound transducers and systems. During these experiments, high power ultrasound transducers are excited by several excitation signals with different amplitudes and frequencies, using a network analyser, a signal generator, a high power amplifier and a multilevel converter. Also, to analyse the behaviour of the ultrasound system, the voltage ratio of the system is measured in different tests. The voltage across transmitter is measured as an input voltage then divided by the output voltage which is measured across receiver. The results of the transducer characteristics and the ultrasound system behaviour are discussed in chapter 4 and 5 of this thesis. Each piezoelectric transducer has several resonance frequencies in which its impedance has lower magnitude as compared to non-resonance frequencies. Among these resonance frequencies, just at one of those frequencies, the magnitude of the impedance is minimum. This resonance frequency is known as the main resonance frequency of the transducer. To attain higher efficiency and deliver more power to the ultrasound system, the transducer is usually excited at the main resonance frequency. Therefore, it is important to find out this frequency and other resonance frequencies. Hereof, a frequency detection method is proposed in this research which is discussed in chapter 2. An extended electrical model of the ultrasound transducer with multiple resonance frequencies consists of several RLC legs in parallel with a capacitor. Each RLC leg represents one of the resonance frequencies of the ultrasound transducer. At resonance frequency the inductor reactance and capacitor reactance cancel out each other and the resistor of this leg represents power conversion of the system at that frequency. This concept is shown in simulation and test results presented in chapter 4. To excite a high power ultrasound transducer, a high power signal is required. Multilevel converters are usually applied to generate a high power signal but the drawback of this signal is low quality in comparison with a sinusoidal signal. In some applications like ultrasound, it is extensively important to generate a high quality signal. Several control and modulation techniques are introduced in different papers to control the output voltage of the multilevel converters. One of those techniques is harmonic elimination technique. In this technique, switching angles are chosen in such way to reduce harmonic contents in the output side. It is undeniable that increasing the number of the switching angles results in more harmonic reduction. But to have more switching angles, more output voltage levels are required which increase the number of components and cost of the converter. To improve the quality of the output voltage signal with no more components, a new harmonic elimination technique is proposed in this research. Based on this new technique, more variables (DC voltage levels and switching angles) are chosen to eliminate more low order harmonics compared to conventional harmonic elimination techniques. In conventional harmonic elimination method, DC voltage levels are same and only switching angles are calculated to eliminate harmonics. Therefore, the number of eliminated harmonic is limited by the number of switching cycles. In the proposed modulation technique, the switching angles and the DC voltage levels are calculated off-line to eliminate more harmonics. Therefore, the DC voltage levels are not equal and should be regulated. To achieve this aim, a DC/DC converter is applied to adjust the DC link voltages with several capacitors. The effect of the new harmonic elimination technique on the output quality of several single phase multilevel converters is explained in chapter 3 and 6 of this thesis. According to the electrical model of high power ultrasound transducer, this device can be modelled as parallel combinations of RLC legs with a main capacitor. The impedance diagram of the transducer in frequency domain shows it has capacitive characteristics in almost all frequencies. Therefore, using a voltage source converter to drive a high power ultrasound transducer can create significant leakage current through the transducer. It happens due to significant voltage stress (dv/dt) across the transducer. To remedy this problem, LC filters are applied in some applications. For some applications such as ultrasound, using a LC filter can deteriorate the performance of the transducer by changing its characteristics and displacing the resonance frequency of the transducer. For such a case a current source converter could be a suitable choice to overcome this problem. In this regard, a current source converter is implemented and applied to excite the high power ultrasound transducer. To control the output current and voltage, a hysteresis control and unipolar modulation are used respectively. The results of this test are explained in chapter 7.

Bioimpedance spectroscopy is very useful in biomedical field as a safe and non-invasive technique. A stable and safe excitation current below than 0.5 mA for load impedances changing from 100 Ω to 10 kΩ in the full β-dispersion range from kHz up to 1 MHz is a big challenge for the design of the current source addressed by this thesis. For a good stability and high accuracy, the source should have a high output impedance. Different current source types in “current-mode approach” and “voltage-mode approach” were investigated and compared for usability in bioimpedance measurement systems. The “voltage-mode approach” with grounded load was proven to be more suitable and stable for biomedical measurements. Thereby the Tietze and the Howland circuit in dual configuration with negative feedback have shown the lowest error of the output current and the highest output impedance, where the improved Howland circuit in dual configuration with negative feedback is preferred because it has a simple structure, high accuracy and good stability. We suggest to improve the stability of the Howland circuit in dual configuration with negative feedback by introducing compensated operational amplifiers and to reduce stray capacitances at higher frequencies by adding gain compensation capacitor. We reach thereby an accuracy of 0.5% at low frequency and 0.9% at 1 MHz. With the realized accuracy of the designed voltage controlled current source, one decisive prerequisite for portable bioimpedance measurement system is achieved. In order to select the appropriate excitation signals for short measurement time, a comparative study of signals and their parameters was carried out. It leads to the selection of binary chirp signal as a suitable excitation signal due to its short measurement time about 100 μs, low crest factor lower than 2.8 and an energy efficiency higher than 54% in a very noisy signal. Simulation results show that the designed enhanced Howland current source excited by the binary chirp signal has low error and flatness in the whole range
Die Bioimpedanzspektroskopie gewinnt aufgrund ihrer besonderen Eigenschaften als nicht-invasive, schonende Messmethode zunehmend an Bedeutung im biomedizinischen Bereich. Dabei ergeben sich besondere erausforderungen für den Entwurf der Stromquelle zur Realisierung eines stabilen und sicheren Anregungsstroms. Gefordert ist eine hohe Genauigkeit bis zu einem Maximalstrom von 0.5 mA in einem Frequenzbereich, der der β-Dispersion entspricht, von wenigen kHz bis hin zu 1 MHz. Die Stabilität muss bei variablen Lastimpedanzen im Bereich von 100 Ω bis 10 kΩ gewährleistet sein. Dafür muss die Stromquelle eine hohe Ausgangsimpedanz aufweisen. Diese Arbeit fokussiert auf den Entwurf von spannungsgesteuerten Stromquellen. Verschiedene Arten von Stromquellen wurden untersucht und verglichen. Der "Voltage-Modus-Ansatz" mit Masse-referenzierter Last hat sich als besser geeignet und stabiler für biomedizinische Messungen erwiesen. Die Tietze-Schaltung und diese Howland-Schaltung zeigen dabei die niedrigsten Fehler des Ausgangsstroms und die höchste Ausgangsimpedanz. Im direkten Vergleich besitzt die verbesserte Howland-Schaltung doch eine einfachere Struktur, höhere Genauigkeit und bessere Stabilität und wird daher gegenüber der Tietze-Schaltung bevorzugt. Um weitere Stabilitätsverbesserungen bei der Howland-Schaltung zu erreichen, werden zwei Maβnahmen vorgeschlagen. Zum einen werden kompensierte Operationsverstärker eingeführt und zum anderen wird der Einfluss von Streukapazitäten bei hohen Frequenzen minimiert indem die Verstärkung mit Kondensatoren kompensiert wird. Durch diese Maβnahmen wird eine Genauigkeit von 0.5% bei niedrigen Frequenzen und 0.9% bei 1 MHz ermöglicht. Mit dem neuen Entwurf der spannungsgesteuerten Stromquelle ist ein entscheidender Meilenstein für die Realisierung tragbarer Messsysteme der Bioimpedanz erreicht. Um eine kurze Messzeit zu realisieren wurde eine vergleichende Studie von Anregungssignalen und deren Signalparameter durchgeführt. Die Ergebnisse zeigen, dass binäre Chirp-Signale aufgrund der reduzierten Messzeit, des niedrigen Crest-Faktors unter 2.8 und hohe Energieeffizienz von mehr als 54% bei hohem Rauschlevel besonders geeignet sind. Simulationsergebnisse zeigen, dass die entwickelte Howland-Stromquelle zusammen mit einem binären Mehrfrequenzsignal den geringsten Amplitudenfehler im gesamten Frequenzbereich realisiert

In dieser Arbeit wird eine, zeitabhängige, nicht störungstheoretische numerische Methode entwickelt, welche Ionisation und Anregung von Atomen oder Molekülen in Stößen mit entweder PB oder P beschreibt und auf der impact-parameter Methode basiert. Es wird eine spektrale close-coupling Methode verwendet, um die zeitabhängige Schrödinger-Gleichung zu lösen, in welcher die Wellenfunktion in (effektive) Ein- oder Zwei-Elektronen-Eigenzustände des Targets entwickelt wird. Dies beinhaltet auch eine erstmalige volle Zwei-Elektronen-Beschreibung von H2 in PB-Stößen. Rechnungen werden für PB-Stöße mit H, H2+ und H2 sowie He und den Alkaliatomen Li, Na, K und Rb durchgeführt. Daten für P-Stöße werden für H2 und die Alkaliatomen Li, Na und K erzielt. Die Methode wird durch einen detaillierten Vergleich der erhaltenen Ergebnisse für P-Stöße und für PB + He mit Literaturdaten verifiziert. Andererseits ergänzen die totalen und differentiellen Wirkungsquerschnitte für Ionisation und Anregung der Targets in PB-Stößen die spärliche Literatur. Sowohl die Resultate für verschiedene Targets als auch für PB- und P-Stöße werden miteinander verglichen. Ein Schwerpunkt dieser Arbeit liegt auf der Untersuchung von PB + H2, welche die Abhängigkeit der Wirkungsquerschnitte vom Kernabstand und von der relativen Ausrichtung der molekularen Achse beinhaltet. Weiterhin werden Ergebnisse mit Ein-Elektronen-Modellpotentialen erzielt und mit der vollen Zwei-Elektronen-Beschreibung von H2 verglichen. Außerdem werden Energieverluste in PB-Stößen bestimmt.
In this work a nonperturbative, time-dependent numerical approach is developed which describes ionization and excitation of atoms or molecules by either PB or P impact based on the impact-parameter method. A spectral close-coupling method is employed for solving the time-dependent Schrödinger equation in which the scattering wave function is expanded in (effective) one- or two-electron eigenstates of the target. This includes for the first time a full two-electron, two-center description of the H2 molecule in PB collisions. The radial part of the one-electron eigenstates is expanded in B splines while the two-electron basis is obtained with a configuration-interaction approach. Calculations are performed for PB collisions with H, H2+, and H2 as well as with He and alkali-metal atoms Li, Na, K, and Rb. Additionally, data are obtained for P collisions with H2, Li, Na, and K. The developed method is tested and validated by detailed comparison of the present findings for P impacts and for PB + He collisions with literature data. On the other hand, total and differential cross sections for ionization and excitation of the targets by PB impact complement the sparse literature data of this kind. Results gained from different targets as well as from PB and P impact are compared with each other and assessed. Furthermore, results obtained with one-electron model potentials are compared to the full two-electron description of H2. Finally, stopping powers for PB impacts are determined.

Les travaux de recherche présentés dans ce mémoire, portent sur la conception et l’étude de MOSFETs de puissance faible tension pour des applications automobiles micro-hybrides de type alterno-démarreur. Pour certaines de ces applications, en plus des modes de fonctionnement standards passant et bloqué, les composants développés doivent être capables de fonctionner en mode d’avalanche à fort courant et à des températures élevées. Pour reproduire en laboratoire ces conditions de fonctionnement, les MOSFETs sont soumis à un test UIS répétitif spécifique. Afin d’évaluer la température du silicium pendant ce test, plusieurs méthodes de mesure de température ont été développées et comparées. En parallèle, un suivi des paramètres électriques standards (BVDSS, IDSS, RDSon…) tout au long du test est effectué, dans le but de déterminer l’impact de l’avalanche répétitive sur le transistor. Seule la RDSon des MOSFETs semble évoluer avec le nombre d’impulsions d’avalanche. Ce phénomène est expliqué par la méthode de mesure de RDSon et par la variation de la résistance du métal source pendant le cyclage. En effet, différentes observations ont permis de constater un vieillissement de la métallisation de source du composant, accompagné d’une modification de sa résistivité. Divers types de métaux et de techniques d’assemblage ont alors été expérimentés pour tenter de limiter cet effet. Aussi des structures de test ont été conçues pour étudier l’évolution du métal et pour pouvoir comparer rapidement le comportement de différentes métallisations
Research work presented in this thesis concern the conception and the study of low voltage power MOSFETs for micro hybrid vehicles (starter alternator). For some of these applications, developed transistors must be able to operate in classical ON and OFF state mode and in avalanche mode at high current and high temperature. To reproduce this operating mode, MOSFETs are submitted to a specific repetitive UIS test. In order to evaluate silicon’s temperature during this test, several temperature measurement methods have been developed and compared. In parallel, in order to understand the impact of repetitive avalanche on the transistor, standard electrical parameters (BVDSS, IDSS, RDSon…) are monitored during the test. The only parameter that seems to be shifting with the number of cycles is the RDSon. This phenomenon is due to the measurement method and to a variation of source metallization resistance during cycling. Indeed several observations have shown source metallization ageing and a shift in its resistivity. Different metallization and assembly parameters have been tested to limit this phenomenon. Also various test structures have been designed to study metallization evolution and to compare different metallization behaviors

New technologies to converting heat into usable energy are constantly being developed for renewable use. This means that more interactions between different energy grid will be applied, such as utilizing low thermal waste heat to convert its energy to electricity. With high electricity price, such technology is quite attractive at applications that develop low waste heat. In the case of excess heat in district heating (DH) grid and the electricity price are high, the waste heat can be converted to electricity, which can bring a huge profit for DH companies. Candidate technologies are many and the focus in this degree rapport is on the so-called Organic Rankine Cycle (ORC) that belongs to the steam Rankine cycle. Instead of using water as a working fluid, organic working fluid is being used because of its ability to boil at lower temperature. Because this technique is available, it also needs to be optimized, developed, etc. to achieve the highest appropriate efficiency. This can be done, for example, by modeling different layouts, analyzing functionality, performance and / or do a simulation of various suitable working fluids.  This is the purpose of this degree project and the research parts are to select working fluids suitable at low temperatures (70-120) °C, the difference analysis between the selected fluids and identification of the parameters that most affect the performance. There are many suitable methods to apply to achieve desired results. The method used in this rapport degree is commercial software such as Mini REFPROP, CoolPack, Excel but the most important part is simulation with AspenPlus. The selected and suitable working fluids between the chosen temperature interval are R236ea, R600, R245fa and n-hexane. Three common layouts were investigated, and they are The Basic ORC, ORC with an internal heat exchanger (IHE) and regenerative ORC. The results show that in comparison between 120°C and 70°C as a temperature source and without an internal heat exchanger (IHE), R600 at 70°C, has the highest efficiency about 13.55%. At 110°C n-hexane has the highest efficiency about 18.10%. R236ea has the lowest efficiency 13.16% at 70°C and 16.29% at 110°C. R236ea kept its low efficiency through all results. Without an IHE and a source range from 70 °C up to almost 90 °C, R600 has the highest efficiency and at 90°C n-hexane has the highest efficiency. With an IHE and between (70-90) °C R245fa still has the highest efficiency. With or without IHE and a heat source of 110 °C n-hexane has the highest efficiency 18.10% and 18.40%. R236ea gets the greatest increase 5.2% in efficiency but remains with the lowest efficiency. With Regenerative ORC, n-hexane had an optimal middle pressure about 0.76 bar. The optimal pressure corresponds to a thermal efficiency of 17.52%. The most important identified parameters are the fluid characteristics such as higher critical temperature, temperature source, heat sink, application placement and component performance.         The current simulations have been run at some fixed data input such as isentropic efficiencies, no pressure drops, adiabatic conditions etc. It was therefore expected that the same efficiency curve would repeat itself. This efficiency pattern would differ with less or higher values depending on the layout performance. However, this pattern was up to 90 degrees Celsius and gets a very noticeable change by the change of the efficiency for n-hexane. Therefore n-hexane is chosen with Regenerative ORC because it had the highest efficiency at the highest temperature source tested. This is due definitive to the fluid properties like its high critical temperature compared to the other selected fluids. R236ea remains the worst and that’s also related to the fluid properties. It is also important to note that these efficiencies are only from a thermodynamic perspective and may differ when combining both thermal and economic perspectives as well as application placement. These high efficiencies will certainly be lower at more advanced or real processes due to various factors that affect performance. Factors such as component´s efficiency and selection, pipe type and size, etc. To maintain a constant temperature when it’s not, flow regulation is then necessary and that’s also affects the performance.   The conclusion is that the basic ORC which does not have an IHE and from 70 up to 90 degrees Celsius, R600 has the highest efficiency. Higher temperature gives n-hexane the highest efficiency. With an IHE and between (70-90) °C R254fa has the highest efficiency. At higher temperature source n-hexane has the highest efficiency. ORC with an IHE has the best performance. The R236ea has the worst performance through all results. With regenerative ORC, an optimal meddle-pressure for n-hexane is 0.76 bar. Important parameters are The properties of the fluid, temperature source, heatsink, Application placement and component performance.
Nej

In questo elaborato vengono mostrati i concetti alla base della piattaforma PULP e il processo di sviluppo di un framework open-source che permette di eseguire benchmark comparativi fra diversi programmi sviluppati per la piattaforma stessa. L'obiettivo del tool sviluppato è quello di fornire agli sviluppatori un metodo rapido ed efficace per confrontare le varie configurazioni possibili dei programmi e permettere loro di vedere facilmente quali siano le impostazioni migliori da utilizzare per raggiungere l'obiettivo desiderato.

In this thesis, the in-duct experimental methods for determining aeroacoustic N-ports of in-duct elements are discussed and improved. The scattering matrix determination methods and the related wave decomposition methods are evaluated from measurements in an empty duct carrying a mean flow. The improvements of a new over-determination method for the source part of the N-port is studied using simulations and measurements; in quiescent air as well as measurements of the flow associated noise of a mixer plate, here a triangular plate inserted at an angle in a duct. The new method is shown to improve suppression of random errors while no improvement is achieved for bias errors.   Further, the methods are applied in the study of two different aeroacoustic phenomena; one is the effect on the flow associated noise of the triangular plate achieved by varying the bending stiffness. For the most resilient plate tested, it is observed that when the Strouhal number of the flow noise coalesce with the Helmholtz number of a specific eigen-mode of the plate, the noise is drastically dampened. There is also a weaker broad band effect.   The other phenomena studied is the amplification and attenuation obtained for sound waves propagating in a T-junction of rectangular ducts. It is found that by adding only 10% of inflow in the side branch relative to that in the main branch, the amplification is heavily increased. By adding another 10% the amplification is again similar to that of no side branch flow. Adding further flow lessens the effects still.
QC 20101118
Experimental characterization of aero-acoustic sources

The theme of this thesis is the design and verification of the auxiliary winding to supply the voltage regulator of the synchronous generator. The synchronous generator for which the auxiliary winding proposed is three-phase, low voltage with double layer random wound stator winding. The generator excitation is brushless with auxiliary rotating exciter. The auxiliary winding is designed for placement in the stator teeth, along with the main winding. The sizing of the auxiliary winding is derived from the power requirements the voltage regulator. Draft winding is validated analytical calculation and finite element method (FEM). The auxiliary winding has been implemented in the production of the generator. The Features of the auxiliary winding have been verified by measuring the by electrical testing room and the test results are evaluated.

The goal of this diploma’s thesis is to inform about present development of light sources, new technologies and about achieved parameters of these light sources. The thesis is mainly directed to describe efficiency of transformation electric energy to light at single types of light sources. There are described the concrete technical parameters of sources quoted by manufacturers and the contructional solution of single types of light sources. There is created a graphic comparation of electrotechnical and light parameters of the light sources.

碩士
崑山科技大學
電機工程研究所
102
Power system surge mainly comprises lightning and switching ones.Their accompanied transient huge energy may destroy electrical equipments.In this thesis, the characteristics of surges including lightning and switching types are introduced. Through the operation measuring data of Air Break Switch of Taipower Company, the switching surge are investigated. The ground potential rise caused by the lightning currents lead to ground will affect the low voltage power source. The transient voltage may damage the electrical devices. The EMTP/ATP program is adopted to simulate the low voltage transients caused by the lightning with different striking positions.Simulations with arresters installed are performed.

碩士
國立臺北科技大學
化學工程研究所
97
In this study, we modify the process of Power MOSFET to improve the device electricity characteristics. We propose the Power MOSFET with the Drain to Source breakdown voltage and Gate Threshold Voltage close in the same chip size condition for the low Drain-Source On-state Resistance optimization design. We reduce the conductive and power loss by the low Drain-Source On-state Resistance. We will utilize: 1. Adjust EPI layer resistance and thickness 2. Adjust Gate Trench depth 3. Adjust the Gate Oxide thickness 4. Adjust the Gate Poly implant dose and driving time 5. Adjust P-Body implant dose and driving time 6. Increase the cell density to reduce the channel and on-state resistance; According to the experiment result, improve Power MOSFET electricity characteristic to reach purpose.

碩士
南台科技大學
電子工程系
95
In this thesis, a low-power high-speed class-B Output buffer for TFT-LCD source driver is proposed. The proposed output buffer employs a complementary differential input to obtain a large input operating range. For the frequency compensation, the conventional method always adopts a miller capacitance, which has area disadvantage. In the proposed circuit, the frequency compensation is realized by only using a compensation resistor to introduce a new zero for stability. The proposed output buffer employs two simple comparators to sense the transients of the input to turn on the output transistors, thus draws little current while static, but has a large driving capability while transient. Moreover, the second output stage is used to improve the speed. The proposed output buffer was simulated basing on 0.35 μm CMOS process. With 3.3 V supply and 600 pF output load, the simulated quiescent current is 3.29 μA. The settling time of rising and falling were 1.88 μs and 1.75 μs, respectively.

碩士
國立臺灣科技大學
電機工程系
105
Many control strategies have been developed for Static Synchronous Compensator (STATCOM) nowadays such as decoupled dq frame control, hysteresis control, predictive control, proportional resonant control, etc. Most of the control methods were designed for low power and high switching frequency systems. However, in high power system, voltage source converters should be operated in low switching frequency in order to reduce switching power loss. Traditional control methods may cause significant steady-state error and affect the effectiveness of current control. This thesis proposes an iterative control method based on Quasi-Newton method, which is more suitable to use at low switching frequency in a high power system. The proposed control strategy is applied for STATCOM in balanced and unbalanced condition to compensate the reactive power at the point of common coupling. The results have been both verified by offline simulation with PSCAD/EMTDC and by hardware-in-the-loop simulation with Real-Time Digital Simulator (RTDS).

abstract: Continuous monitoring in the adequate temporal and spatial scale is necessary for a better understanding of environmental variations. But field deployments of molecular biological analysis platforms in that scale are currently hindered because of issues with power, throughput and automation. Currently, such analysis is performed by the collection of large sample volumes from over a wide area and transporting them to laboratory testing facilities, which fail to provide any real-time information. This dissertation evaluates the systems currently utilized for in-situ field analyses and the issues hampering the successful deployment of such bioanalytial instruments for environmental applications. The design and development of high throughput, low power, and autonomous Polymerase Chain Reaction (PCR) instruments, amenable for portable field operations capable of providing quantitative results is presented here as part of this dissertation. A number of novel innovations have been reported here as part of this work in microfluidic design, PCR thermocycler design, optical design and systems integration. Emulsion microfluidics in conjunction with fluorinated oils and Teflon tubing have been used for the fluidic module that reduces cross-contamination eliminating the need for disposable components or constant cleaning. A cylindrical heater has been designed with the tubing wrapped around fixed temperature zones enabling continuous operation. Fluorescence excitation and detection have been achieved by using a light emitting diode (LED) as the excitation source and a photomultiplier tube (PMT) as the detector. Real-time quantitative PCR results were obtained by using multi-channel fluorescence excitation and detection using LED, optical fibers and a 64-channel multi-anode PMT for measuring continuous real-time fluorescence. The instrument was evaluated by comparing the results obtained with those obtained from a commercial instrument and found to be comparable. To further improve the design and enhance its field portability, this dissertation also presents a framework for the instrumentation necessary for a portable digital PCR platform to achieve higher throughputs with lower power. Both systems were designed such that it can easily couple with any upstream platform capable of providing nucleic acid for analysis using standard fluidic connections. Consequently, these instruments can be used not only in environmental applications, but portable diagnostics applications as well.
Dissertation/Thesis
Ph.D. Electrical Engineering 2013

博士
國立中央大學
電機工程學系
101
This thesis is primarily targeted to design and implement the key component, mixer, for V-band radio frequency (RF) transceiver front-end using source-driven technology. There are two source-driven mixers are investigated based on 90-nm CMOS process that include both up-conversion and down-conversion topologies. The main design goals aim towards high conversion gain (CG), linearity, and port-to-port isolations under ultra-low voltage low power operations. In the thesis, Chapter 3 proposes a novel up-conversion mixer with pseudo-differential and current-reused topology in TSMC standard 90 nm CMOS technology. The proposed source-pumped up-conversion mixer can operate at near weak inversion under a power consumption of 149 W from a 0.4-V supply voltage while maintains acceptable circuit performance at millimeter-wave (MMW) frequencies. The up-conversion mixer achieves a -0.62 dB conversion gain and a -4 dBm OIP3 in measurements. The measured 3-dB frequency bandwidth ranges from 17.3 to 22.5 GHz. The best figure-of-merit (FOMUp-M) acquires as high as 33.2 under a 0.3-V supply. The chip size including all pads and dummy blocks is 0.72 mm2. Chapter 4 proposes a microwatt (W) source-driven down-conversion mixer with broadband asymmetrical broadside-coupled baluns in UMC 90-nm CMOS low-power (LP) process. The forward body biased (FBB) technique reduces the threshold voltage (VTH) and supply voltage for operation in the near weak inversion region in MMW active mixer designs. To effectively reduce the size of the chip, an asymmetrical broadside-coupled balun is developed with a bandwidth (BW) of 103 GHz (from 34 to 137 GHz) with a low insertion loss of 3.66 dB (3 dB for an ideal balun) at 58 GHz. The chip area of the balun is 0.016 mm2. The proposed FBB mixer has a 4.2-dB peak CG and a 14.3-dBm input IP3 at 55 GHz under a 2-dBm LO power input. The DC power of the FBB mixer core is only 139 W, while it draws a 278-A DC current from a 0.5-V supply. The fabricated FBB mixer, comprising two asymmetrical broadside-coupled baluns, and all of test pads and dummy blocks, occupies an area of 0.72 mm2. An FOMDown-M2 that is obtained using the ultra-low power consumption FBB mixer is as high as 39.1.

With the prevalence of smartphones, pedestrians and joggers today often walk or run while listening to music. Since they are deprived of auditory stimuli that could provide important cues to dangers, they are at a much greater risk of being hit by cars or other vehicles. We start this research into building a wearable system that uses multichannel audio sensors embedded in a headset to help detect and locate cars from their honks and engine and tire noises. Based on this detection, the system can warn pedestrians of the imminent danger of approaching cars. We demonstrate that using a segmented architecture and implementation consisting of headset-mounted audio sensors, front-end hardware that performs signal processing and feature extraction, and machine-learning-based classification on a smartphone, we are able to provide early danger detection in real time, from up to 80m distance, with greater than 80% precision and 90% recall, and alert the user on time (about 6s in advance for a car traveling at 30mph). The time delay between audio signals in a microphone array is the most important feature for sound-source localization. This work also presents a polarity-coincidence, adaptive time-delay estimation (PCC-ATDE) mixed-signal technique that uses 1-bit quantized signals and a negative-feedback architecture to directly determine the time delay between signals in the analog inputs and convert it to a digital number. This direct conversion, without a multibit ADC and further digital-signal processing, allows for ultra low power consumption. A prototype chip in 0:18μm CMOS with 4 analog inputs consumes 78nW with a 3-channel 8-bit digital time-delay output while sampling at 50kHz with a 20μs resolution and 6.06 ENOB. We present a theoretical analysis for the nonlinear, signal-dependent feedback loop of the PCC-ATDE. A delay-domain model of the system is developed to estimate the power bandwidth of the converter and predict its dynamic response. Results are validated with experiments using real-life stimuli, captured with a microphone array, that demonstrate the technique’s ability to localize a sound source. The chip is further integrated in an embedded platform and deployed as an audio-based vehicle-bearing IoT system. Finally, we investigate the signal’s envelope, an important feature for a host of applications enabled by machine-learning algorithms. Conventionally, the raw analog signal is digitized first, followed by feature extraction in the digital domain. This work presents an ultra-low-power envelope-to-digital converter (EDC) consisting of a passive switched-capacitor envelope detector and an inseparable successive approximation-register analog-to-digital converter (ADC). The two blocks integrate directly at different sampling rates without a buffer between them thanks to the ping-pong operation of their sampling capacitors. An EDC prototype was fabricated in 180nm CMOS. It provides 7.1 effective bits of ADC resolution and supports input signal bandwidth up to 5kHz and an envelope bandwidth up to 50Hz while consuming 9.6nW.

碩士
國立中興大學
精密工程學系所
104
This study focused on using chemical selective etching (CSE) to fabricate GaAs thin-film solar cells and discussed their characteristics. Additionally, the technique of the recyclable GaAs substrate was developed and realized. This was not only able to obtain a high efficiency solar cell, but also reduce the fabrication cost. All GaAs solar cells were applied to mobile power packs for comparing their device performance. Under CSE process, the AlAs was regarded as a sacrificial layer, which was be etched to assist in the separation of the solar cell epilayer from GaAs substrate. Then the GaAs substrate could be recycled for the next usage as a growth template. The finishing time of completely separating the whole epilayer from four-inch GaAs cell was about 6-10 hours. Thin film solar cells can be transferred to Ni substrate with high thermal dissipation and light weight by means of CSE process. On the other hand, the recycled GaAs substrate was cleaned by the mixture solution of hydrogen peroxide and ammonia and the mixture solution of phosphoric acid and hydrochloric acid, and then it could be reused for the solar cell epitaxial growth by metal-organic chemical vapor deposition. Afterwards, this thin film solar cell was coated with the n-type electrode and an anti-reflective layer to increase the optical path for enhancing the photocurrent. This thesis composed three parts. First of all, the influences of different skills including bending and unbending temporary substrates on the characteristics of solar cells were discussed. In the second part, four different areas of solar cells were designed, such as 0.03 cm2, 0.25 cm2, 0.64 cm2, and 1 cm2, respectively. In addition, the effects of distinct materials of anti-reflective layers and two kinds of base layer thicknesses on the characteristics of devices were also explored. Finally, the GaAs-based solar cells were actually used to fabricate a module of portable power source. Furthermore, the performance of the portable power source constructed by GaAs-based solar cell was compared with that built by commercial Si-based solar cells.

碩士
國立交通大學
控制工程系
82
The purpose of this theis is to analyze and implement an ac power source system based on digital signal processors (DSP) usingthe repetitive control algorithm. (1) To established a mathematic model of a PWM controlled inverter system.Authors have investigated the reason why the output waveform of an ac power sourcemay be distorted due to connected nonlinear loads. Much previous research was explored from the standpoint of instant-command tracking and steady- state regulation. A PWM inverter was model by its dynamic equations and the optimal state feedback method was investigated to govern the transient response of the ac source systems. (2) To propose a control strategy and an algorithm for ac voltage regulation of a PWM inverter. According to the built control system, a repetitive control strategy was proposed to improve the steady-state reponse under the assumption of periodic disturbances. Authos discussed a sufficient condition of the stability of the repetitive control system and the convergence of the error induced by periodic disturbances from the Nyquist criterion in discrete-time domain. Under this sufficient condition, the response to harmonic inputs and to non-harmonic inputs could be predicted. (3) To design a TMS320C14 DSP-basd control board. The TMS320C14 control board included an eight-channel A/D converter and memory devices. In this control board, PWM switching signals and feedback signals can communicate between the digital controller and the power stage. The read-write memory device was needed for the implement of the time-delay function in the repetitive control system. A numverical realization of the repetitive control algorithm applied on the control of a PWM inverter has been presented. According to the characteristics of the well-design servo control system, all of the blocks in the repetitive control system can be determined from the sufficient condition.