To see the other types of publications on this topic, follow the link: Piezoelectric transformer.
Dissertations / Theses on the topic 'Piezoelectric transformer'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Piezoelectric transformer.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Sharapov, V. M., and K. V. Bazilo. "Piezoelectric transformer with parallel oscillatiry circuit." Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/39938.
Full textAbstract:
Piezoelectric transducers are widely used in electroacoustics, hydroacoustics, in ultrasound, medical, measurement technique, in scanning probe nanomicroscopes, piezoengines and in other fields of science and technology. To create transducers with necessary characteristics the technology of additional elements can be used.
2
Lin, Chih-yi. "Design and Analysis of Piezoelectric Transformer Converters." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30723.
Full textAbstract:
Piezoelectric ceramics are characterized as smart materials and have been widely used in the area of actuators and sensors. The principle operation of a piezoelectric transformer (PT) is a combined function of actuators and sensors so that energy can be transformed from electrical form to electrical form via mechanical vibration.
Since PTs behave as band-pass filters, it is particularly important to control their gains as transformers and to operate them efficiently as power-transferring components. In order to incorporate a PT into amplifier design and to match it to the linear or nonlinear loads, suitable electrical equivalent circuits are required for the frequency range of interest. The study of the accuracy of PT models is carried out and verified from several points of view, including input impedance, voltage gain, and efficiency.
From the characteristics of the PTs, it follows that the efficiency of the PTs is a strong function of load and frequency. Because of the big intrinsic capacitors, adding inductive loads to the PTs is essential to obtain a satisfactory efficiency for the PTs and amplifiers. Power-flow method is studied and modified to obtain the maximum efficiency of the converter. The algorithm for designing a PT converter or inverter is to calculate the optimal load termination, YOPT, of the PT first so that the efficiency (power gain) of the PT is maximized. And then the efficiency of the dc/ac inverter is optimized according to the input impedance, ZIN, of the PT with an optimal load termination.
Because the PTs are low-power devices, the general requirements for the applications of the PTs include low-power, low cost, and high efficiency. It is important to reduce the number of inductive components and switches in amplifier or dc/ac inverter designs for PT applications. High-voltage piezoelectric transformers have been adopted by power electronic engineers and researchers worldwide. A complete inverter with HVPT for CCFL or neon lamps was built, and the experimental results are presented. However, design issues such as packaging, thermal effects, amplifier circuits, control methods, and matching between amplifiers and loads need to be explored further.Ph. D.
3
Fung, Sze-wei, and 馮時維. "Modeling the rosen type piezoelectric transformer for powerconverters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31451226.
Full text
4
Olding, Timothy Russell. "A thin film piezoelectric transformer for silicon integration." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0005/MQ42673.pdf.
Full text
5
Benwell, Andrew L. Kovaleski Scott D. "A high voltage piezoelectric transformer for active interrogation." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6847.
Full textAbstract:
Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 23, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Scott D. Kovaleski. Vita. Includes bibliographical references.
6
Lin, Ray-Lee. "Piezoelectric Transformer Characterization and Application of Electronic Ballast." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29948.
Full textAbstract:
The characterization and modeling of piezoelectric transformers are studied and developed for use in electronic ballasts. By replacing conventional L-C resonant tanks with piezoelectric transformers, inductor-less piezoelectric transformer electronic ballasts have been developed for use in fluorescent lamps.
The piezoelectric transformer is a combination of piezoelectric actuators as the primary side and piezoelectric transducers as the secondary side, both of which work in longitudinal or transverse vibration mode. These actuators and transducers are both made of piezoelectric elements, which are composed of electrode plates and piezoelectric ceramic materials. Instead of the magnetic field coupling between the primary and secondary windings in a conventional magnetic core transformer, piezoelectric transformers transfer electrical energy via electro-mechanical coupling that occurs between the primary and secondary piezoelectric elements for isolation and step-up or step-down voltage conversion. Currently, there are three major types of piezoelectric transformers: Rosen, thickness vibration mode, and radial vibration mode, all three of which are used in DC/DC converters or in electronic ballasts for fluorescent lamps. Unlike the other two transformers, the characterization and modeling of the radial vibration mode piezoelectric transformer have not been studied and developed prior to this research work.
Based on the piezoelectric and wave equations, the physics-based equivalent circuit model of radial vibration mode piezoelectric transformers is derived and verified through characterization work.
Besides the major vibration mode, piezoelectric transformers have many spurious vibration modes in other frequency ranges. An improved multi-branch equivalent circuit is proposed, which more precisely characterizes radial vibration mode piezoelectric transformers to include other spurious vibration modes in wide frequency ranges, as compared with the characterizations achieved by prior circuits.
Since the equivalent circuit of piezoelectric transformers is identical to the conventional L-C resonant tank used in electronic ballasts for fluorescent lamps, piezoelectric transformers replace the conventional L-C resonant tank in order to reduce the amount and cost of electronic components for the electronic ballasts. With the inclusion of the radial vibration mode piezoelectric transformer, the design and implementation of inductor-less piezoelectric transformer electronic ballast applications have been completed.Ph. D.
7
Fung, Sze-wei. "Modeling the rosen type piezoelectric transformer for power converters." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31451226.
Full text
8
Do, Manh Cuong. "Piezoelectric transformer integration possibility in high power density applications." Doctoral thesis, Dresden : TUDpress Verl. der Wiss, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1214984646187-55994.
Full text
9
Do, Manh Cuong. "Piezoelectric Transformer Integration Possibility in High Power Density Applications." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23676.
Full textAbstract:
The contents of this work investigate the capability of integrating the PT in applications by invoking the ratio of the throughput power to volume represented by the term: power density. The fundamentals of the PT are introduced in chapter two. In chapter three, the fundamental limitations of the PT's capability of transferring power to the load are studied. There are three major limitations: temperature rise due to losses during operation, electromechanical limits of material, and interactions with output rectifier. The analysis and estimation are then verified by experiments and calculations implemented on three different PT samples fabricated from three different manufacturers. The subject of chapter four is the behavior of the PT's power amplifier. This chapter concentrates on two main amplifier topologies, optimized based on the simplicity of structure and minimization of components (passive and active): class D and class E amplifiers. The operational characteristics of these amplifiers with the PT are then comparison. Methods to track the optimum frequency and discontinuous working mode of the PT are proposed as the approaches to improve the energy transfer of the PT. In chapter five, prototypes of four devices using a PT are developed and introduced as illustrations of the integration of PTs into practical applications: an igniter for high intensity discharge (HID) lamps, high DC voltage power supplies, and electronic ballasts for LEDs, and stand-alone ionizers for food sterilizers. Some concluding statements and ideas for future works are located in the last chapter - chapter six.
10
Roberts, Anthony M. "Implementing a Piezoelectric Transformer for a Ferroelectric Phase Shifter Circuit." Cleveland State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=csu1337025849.
Full text
11
Huang, Weixing. "Design of a Radial Mode Piezoelectric Transformer for a Charge Pump Electronic Ballast with High Power Factor and Zero Voltage Switching." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31818.
Full textAbstract:
In a conventional electronic ballast for a fluorescent lamp, inductor-capacitor-transformer
tank circuit is used. A Piezoelectric Transformer (PT) can potentially be used
to replace such a tank circuit to save space and cost. In the past, ballast design using a PT
requires selecting a PT from available samples which are normally not matched to
specific application and therefore resulting in poor performance. In this thesis, a design
procedure was proposed for designing a PT tailored for a 120-V 32-W electronic ballast
with high power factor, high efficiency and Zero-Voltage-Switching (ZVS) of the
inverter transistors that drive the lamp. This involves selection of PT materials,
determination of geometries and the number of physical layers of the PT. A radial mode
piezoelectric transformer prototype based on this design process was fabricated by Face
Electronics Inc. and was tested experimentally, the results showed that the ballast using
this custom-made PT achieved high power factor, Zero-Voltage-Switching and a 83%
overall efficiency.Master of Science
12
Baker, Eric Matthew. "Design of Radial Mode Piezoelectric Transformers for Lamp Ballast Applications." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32362.
Full textAbstract:
In the past, radial-mode piezoelectric transformer (Transoner) design has been
difficult due to the complex interaction between the physical and electrical circuit
characteristics. Prior to a design procedure, experimental design by Face Electronics, LC
led to a sample that could fit a ballast application enabling zero voltage switching (ZVS)
for the semiconductors without the use of any external inductance.
In the ballast circuit, the piezoelectric transformer is used to replace the
conventional inductor-capacitor resonant tank saving valuable space and expense. With
ballast in mind, a design process has been developed in this thesis to optimize radial
mode transformers to fit specifically tailored applications. The graphical process
described, allows the engineer to design in the capability of zero voltage switching for a
half-bridge drive while simultaneously providing highly efficient performance.
The problem of mounting a piezoelectric transformer to a circuit board has also
been addressed in this thesis. A thermally conductive mounting technique has been
developed which can enhance both the power capability and reliability of circuits
utilizing these devices.Master of Science
13
[Verfasser], Đ~ô-mạnh-Cuong. "Piezoelectric transformer integration possibility in high power density applications / Do Manh Cuong." Dresden : TUDpress, 2008. http://d-nb.info/1000793125/34.
Full text
14
Bazilo, C. V. "Mathematical modelling of disk piezoelectric transformer with ring electrode in primary electrical circuit." Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/65602.
Full textAbstract:
In most papers the described methods of piezoelectric transformers
models constructing are mostly based on the use of equivalent electrical
circuits and it does not allow analyzing of stress-strain state of solids with
the piezoelectric effects.
In this work, using the simplest example of axially symmetric radial oscillations
of the piezoelectric disk the principles of mathematical models
constructing that are sufficiently adequate to real devices and occurring
physical processes are set out.
15
Zhou, Yuan. "Magnetoelectric Composites for On-Chip Near-Resonance Applications." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/50488.
Full textAbstract:
Magnetoelectric (ME) effect is defined as the change in dielectric polarization (P) of a material under an applied magnetic field (H) or an induced magnetization (M) under an external electric field (E). ME materials have attracted number of investigators due to their potential for improving applications such as magnetic field sensors, filters, transformers, memory devices and energy harvesters. It has been shown both experimentally and theoretically that the composite structures consisting of piezoelectric and magnetostrictive phases possess stronger ME coupling in comparison to that of single phase materials. Giant magnetoelectric effect has been reported in variety of composites consisting of bulk-sized ME composites and thin film ME nanostructures. In this dissertation, novel ME composite systems are proposed, synthesized and characterized in both bulk and thin films to address the existing challenges in meeting the needs of practical applications. Two applications were the focused upon in this study, tunable transformer and dual phase energy harvester, where requirements can be summarized as: high ME coefficient under both on-resonance and off-resonance conditions, broad bandwidth, and low applied DC bias.
In the first chapter, three challenges related to the conventional ME behavior in bulk ME composites have been addressed (1) The optimized ME coefficient can be achieved without external DC magnetic field by using a self-biased ME composite with a homogenous magnetostrictive material. The mechanism of such effect and its tunability are studied; (2) A near-flat ME response regardless of external magnetic field is obtained in a self-biased ME composite with geometry gradient structure; (3) By optimizing interfacial coupling with co-firing techniques, the ME coefficient can be dramatically enhanced. Theses co-fired ME laminates not only exhibit high coupling coefficient due to direct bonding, but also illustrate a self-biased effect due to the built-in stress during co-sintering process. These results present significant advancement toward the development of multifunctional ME devices since it eliminates the need for DC bias, expands the working bandwidth and enhances the ME voltage coefficient.
Next, magnetoelectric nanocomposites were developed for understanding the nature of the growth of anisotropic thin film structures. In this chapter following aspects were addressed: (1) Controlled growth of nanostructures with well-defined morphology was obtained. Microstructure and surface morphology evolution of the piezoelectric BaTiO3 films was systematically analyzed. A growth model was proposed by considering the anisotropy of surface energy and the formation of twin lamellae structure within the frame work of Structure Zone Model (SZM) and Dynamic Scaling Theory (DST). In parallel to BaTiO3 films, well-ordered nanocomposite arrays [Pb1.1(Zr0.6Ti0.4)O3/CoFe2O4] with controlled grain orientation were developed and investigated by a novel hybrid deposition method. The influence of the pre-deposited template film orientation on the growth of ME composite array was studied. (2) PZT/CFO/PZT thick composite film and BTO/CFO thin film were synthesized using sol-gel deposition (SGD) and pulsed laser deposition (PLD) techniques, respectively. The HRTEM analysis revealed local microstructure at the interface of consecutive constituents. The interfacial property variation of these films was found to affect the coupling coefficient of corresponding ME nanocomposites. Subsequently, a novel complex three-dimensional ME composite with highly anisotropic structure was developed using a hybrid synthesis method. The influence of growth condition on the microstructure and property of the grown complex composites was studied. The film with highly anisotropic structure was found to possess tailored ferroelectric response indicating the promise of this synthesis method and microstructure.
Based on the laminated ME composites, three types of ME tunable transformer designs were designed and fabricated. The goal was to develop a novel ME transformer with tunable performance (voltage gain and/or working resonance frequency) under applied DC magnetic field. Conventional ME transformers need either winding coil or large external magnetic field to achieve the tunable feature. Considering the high ME coupling of ME laminate, two ME transformers were developed by epoxy bonding Metglas with transversely/longitudinally poled piezoelectric ceramic transformer. The influence of different operation modes toward magnetoelectric tunability was analyzed. In addressing the concern of the epoxy bonding interface, a co-fired ME transformer with unique piezoelectric transformer/magnetostrictive layer/piezoelectric transformer trilayer structure was designed. The design and development strategy of thin film ME transformer was discussed to illustrate the potential for ME transformer miniaturization and on-chip integration.
Lastly, motivated by the increasing demand of energy harvesting (EH) systems to support self-powered sensor nodes in structural health monitoring system, a magnetoelectric composite based energy harvester was developed. The development and design concept of the magnetoelectric energy harvester was systematically discussed. In particular, the first dual-phase self-biased ME energy harvester was designed which can simultaneously harness both vibration and stray magnetic field (Hac) in the absence of DC magnetic field. Strain distribution of the EH was simulated using the finite element model (FEM) at the first three resonance frequencies. Additionally, the potential of transferring this simple EH structure into MEMS scalable components was mentioned. These results provide significant advancement toward high energy density multimode energy harvesting system.Ph. D.
16
Su, Yu-Hao. "Power Enhancement of Piezoelectric Technology based Power Devices by Using Heat Transfer Technology." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0025/document.
Full textAbstract:
L’objectif de cette étude est d’améliorer les performances des transformateurs piézoélectriques en terme de courant de sortie et de puissance pour des applications d’alimentation DC/DC, grâce à la gestion de l’échauffement. Le courant de sortie des transformateurs piézoélectriques, et donc la puissance transmise, sont directement liés à la vitesse de vibration qui pour des valeurs élevées engendre des pertes et une forte élévation de température. Cette élévation excessive de la température a comme conséquence le changement des caractéristiques du transformateur et plus particulièrement la diminution du facteur de qualité Q. Ainsi cela entraine une limite structurelle de la puissance transmise du transformateur. Une solution pour augmenter le courant de sortie est l’utilisation d’un redresseur doubleur de courant, qui grâce à 2 inductances permet, à courant de charge donné, de diminuer la vitesse de vibration du transformateur, mais ne permet pas de régler le problème d’échauffement du transformateur. Dans cette thèse nous proposons des moyens d’évacuation de la chaleur ainsi que le choix de l’environnement dans lequel le transformateur devra fonctionner. L’influence de différents systèmes de refroidissement d’un convertisseur DC/DC à base transformateur piézoélectrique est étudiée. L’étude thermique du transformateur piézoélectrique multicouche polarisé en épaisseur et ayant des électrodes circulaires met en évidence un comportement non linéaire. Une plaque vibrante piézoélectrique est d’abord envisagée pour créer un flux d’air qui augmente l’évacuation de chaleur par convection, puis un module de refroidissement utilisant l’effet thermoélectrique. Les mesures montrent que la première solution est plus avantageuse car elle améliore sensiblement les performances du transformateur pour un coût énergétique très faible. Une étude thermique par éléments finis complète cette étude, montrant que l’approche par schéma électrique est pertinente. La puissance que peut délivrer le transformateur sur une charge optimale est encore augmentée. Enfin, ce travail montre qu’en combinant les dispositifs de refroidissement tout en respectant la condition de température inférieure à 55°C, le rendement du convertisseur reste raisonnable (70%) et la puissance disponible peut doubler dans le meilleur des casThe objective of this study was to increase the output current and power in a piezoelectric transformer (PT) based DC/DC converter by adding a cooling system. It is known that the output current of PT is limited by temperature build-up because of losses especially when driving at high vibration velocity. Excessive temperature rise will decrease the quality factor Q of piezoelectric component during the operational process. Simultaneously the vibration energy cannot be increased even if under higher excitation voltage. Although connecting different inductive circuits at the PT secondary terminal can increase the output current, the root cause of temperature build-up problem is not solved.This dissertation presents the heat transfer technology to deal with the temperature build-up problem. With the heat transfer technology, the threshold vibration velocity of PT can be increased and thus the output current and output power (almost three times).Furthermore, a comparison between heat transfer technology and current-doubler rectifier applied to the piezoelectric transformer based DC/DC converter was also studied. The advantages and disadvantages of the proposed technique were investigated. A theoretical-phenomenological model was developed to explain the relationship between the losses and the temperature rise. It will be shown that the vibration velocity as well as the heat generation increases the losses. In our design, the maximum output current capacity can increase 100% when the operating condition of PT temperature is kept below 55°C. The study comprises of a theoretical part and experimental proof-of-concept demonstration of the proposed design method
17
Белякова, Ірина Володимирівна, Ирина Владимировна Белякова, and I. Belyakova. "Моделювання та розрахунок п’єзотрансформаторів, навантажених люмінесцентною лампою." Thesis, Тернопільський національний технічний університет ім. Івана Пулюя, 2012. http://elartu.tntu.edu.ua/handle/123456789/1892.
Full textAbstract:
Роботу виконано у Тернопільському національному технічному університеті імені Івана Пулюя Міністерства освіти і науки, молоді та спорту України. Захист відбувся 23 березня 2012 р. об 11.00 годині на засіданні спеціа-лізованої вченої ради К 58.052.04 у Тернопільському національному техніч-ному університеті імені Івана Пулюя (46001. Україна, м. Тернопіль, вул. Ру-ська, 56).
З дисертацією можна ознайомитися у бібліотеці Тернопільського націо-нального технічного університету ім. Івана Пулюя (46001, Україна, м. Терно-піль, вул. Руська, 56).У дисертації проведено дослідження високочастотних напівпровід-никових пускорегулюючих апаратів (НПРА) на базі п’єзоелектричного тран-сформатора струму (ПТ), а також розроблено методику розрахунку, яка вра-ховує як особливості самого ПТ, так і його нелінійного навантаження, яким є люмінесцентна лампа (ЛЛ) у схемах стартерного та безстартерного ввімк-нення в пусковому та робочому режимах. Розроблено та змонтовано експериментальні установки для вимірювання характеристик ПТ струму в схемах стартерного та безстартерного ввімкнення люмінесцентних ламп, за допомогою яких досліджувалися характеристики п’єзотрансформаторів струму. Розроблено схему високочастотного перетворювача, який забезпечує на-дійне функціонування ПТ в усіх можливих режимах його роботи (холостий хід, коротке замикання, режим максимального ККД); розроблено методику розрахунку конструктивних та електричних параметрів п’єзотрансформатора, що може бути рекомендована для розрахунку параметрів п’єзотрансфор-матора з нелінійним навантаженням, яким є люмінесцентна лампа. Проведено експериментальні дослідження впливу зміни параметрів на-вантаження, напруги та частоти джерела живлення, температури довкілля на параметри п’єзотрансформатора. Удосконалено математичну модель п’єзоелектричного трансформа-тора, яка базується на експериментально визначених характеристиках нелі-нійного чотириполюсника, що дозволило розробити методику розрахунку параметрів комплекту ПТ–ЛЛ у пусковому та робочому режимах.
В диссертации проведены исследования для создания высокочастот-ного полупроводникового пускорегулирующего аппарата (ППРА) на базе пьезоэлектрического трансформатора тока (ПТ), а также разработана мето-дика расчета, учитывающая как особенности самого ПТ, так и его нелиней-ной нагрузки, которой является люминесцентная лампа (ЛЛ) мощностью 4 ... 18 Вт в схемах стартерного и безстартерного включения в пусковом и рабо-чем режимах работы. Разработаны и смонтированы экспериментальные установки для изме-рения характеристик ПТ тока в схемах стартерного и безстартерного вклю-чения люминесцентных ламп, с помощью которых исследовались характери-стики пьезотрансформаторов тока. Разработана схема высокочастотного преобразователя, который обеспе-чивает надежное функционирование ПТ во всех возможных режимах его ра-боты (холостой ход, короткое замыкание, режим максимального КПД); раз-работана методика расчета конструктивных и электрических параметров пье-зотрансформатора, которая может быть рекомендована для расчета парамет-ров пьезотрансформатора с нелинейной нагрузкой, которой является люми-несцентная лампа. Проведены экспериментальные исследования влияния изменения пара-метров нагрузки, напряжения и частоты источника питания, температуры ок-ружающей среды на параметры пьезотрансформатора. Разработаны принципы построения ППРА для ЛЛ на основе пьезотран- сформаторов тока, которые позволяют повысить эффективность и экономич-ность электронных балластов. Усовершенствована математическая модель пьезоэлектрического транс- форматора, которая базируется на экспериментальных характеристиках не-линейного четырехполюсника, что позволило разработать методику расчета параметров комплекта ПТ-ЛЛ в пусковом и рабочем режимах работы. Впервые дано математическое обоснование возникновения нелиней-ных функциональных зависимостей параметров пьезотрансформатора, нагружен-ного люминесцентной лампой.
In this work the studies of high-frequency semiconductor starter devices, based on piezoelectric current transformers, were undertaken, and the method of calculation was devised, which takes into account both - properties of the piezoelectric transformer and its non-linear load (which is a fluorescent lamp) during launch and in operational modes, with and without starter arrangements. The experimental equipment for measuring the properties of piezoelectric transformer and currents it produces, in arrangement with and without a starter, was designed and constructed. The scheme for high-frequency transducer was devised, which provides reliable operation of piezoelectric transformer in all possible modes of operation (idling, short circuit, the regime of maximum efficiency); the method of calculation of structural and electrical properties of piezoelectric transformer was also developed, which could be recommended for calculating the properties of piezoelectric transformer with non-linear load (e.g. fluorescent lamp). Experimental studies of the impact the change in load, current, frequency of power source and ambient temperature has on the properties of piezoelectric transformer have been conducted. The mathematical model of piezoelectric transformer has been improved, which is based on the properties of non-linear quadripole that have been established by the experiment. This has enabled to develop the methodology for calculation of the parameters of combination of piezoelectric transformer and fluorescent lamp during launch and in operational modes.
18
Заика, В. М., and Ю. Ю. Бондаренко. "Пьезотрансформатор с колебательными системами различной физической природы." Thesis, Сумский государственный университет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/41013.
Full textAbstract:
Пьезоэлектрические преобразователи широко используются в ультразвуковой измерительной технике. Пьезоэлектрическим трансформатором условно может быть назван пьезоэлемент с тремя
и более электродами, подключаемыми к одному или нескольким источникам электрического сигнала.
19
Martinez, Thomas. "Etude d'un transformateur piézoélectrique à onde progressive et de son application aux convertisseurs de puissance." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN047/document.
Full textAbstract:
Les transformateurs piézoélectriques présentent de nombreux intérêts en électronique de puissance par rapport aux transformateurs magnétiques : gains en tension élevé, forte densité de puissance, compacité, rendements élevés, forte isolation galvanique et faibles rayonnement électromagnétiques. Toutefois, les structures classiques sont basées sur la génération d’une onde stationnaire qui limite le nombre d’électrodes et de tensions disponibles en sortie. Dans cette thèse, nous proposons une nouvelle topologie de transformateur piézoélectrique qui utilise une onde progressive au lieu d’une onde stationnaire. Avec cette solution, il est possible d’obtenir un système polyphasé de tensions en sortie du transformateur ce qui rend possible plusieurs types de conversion (DC-DC, DC-AC à fréquence variable).Dans un premier temps, nous avons développé un nouveau modèle analytique permettant de décrire le comportement du transformateur à partir de ses dimensions et des propriétés du matériau. Différents prototypes ont été développés pour valider le concept du transformateur et des séries de mesures ont permis de valider le modèle. Concernant les performances, un transformateur cylindrique basé sur une onde de volume a pu fournir un système quadriphasé avec une puissance maximale de 6 W et des rendements de 90%.Une autre approche visait à décrire le comportement d’un transformateur déjà réalisé par l’extraction de ses paramètres Y. A partir de cela, une représentation compatible avec les logiciels de simulation de type Spice a permis une simulation précise du transformateur et du convertisseur de puissance associé.Enfin, deux convertisseurs de puissances ont été conçus basés sur ce transformateur à onde progressive. Le premier est un convertisseur DC-DC basé sur un redresseur polyphasé pour l’alimentation de drivers isolés. Les différentes tensions disponibles à la sortie permettent l’alimentation de plusieurs drivers avec un seul transformateur. Le second convertisseur est un convertisseur DC-AC basé sur le principe d’un cycloconvertisseur. La recombinaison des phases à la sortie permet d’obtenir un signal ACPiezoelectric transformers propose several advantages over magnetic ones for power conversion : high voltage gain, compactness, high power density, high efficiency due to their high quality factor, strong galvanic isolation and low electro-magnetic emissions. However, in general, they are based on the generation of a standing wave that limits the number of electrodes at the surface of the transformer. In this PhD, we propose the use of a traveling wave instead of a standing wave. With this solution, it is possible to obtain a multi-phase system of voltages at the output which makes it suitable for different types of conversion (DC-DC, DC-AC with variable frequency).During this work, we developed a new analytical modelling of the transformer that describes its electrical behavior based on geometry and material properties. Different prototypes of TWPT were conceived to validate the concept and on which we perform measurements to validate the analytical modelling. Among them, cylinder-type TWTP based on longitudinal waves outputs a four-phase system with an output power of 6 W and efficiencies as high as 90%.A second approach developed consisted in the modelling of an already made transformer based on the experimental extraction of admittance parameters and its representation for simulation in Spice-type software. This approach allows for precise simulation of the transformer and the associated power converters.Finally, we designed two power converters based on this traveling wave piezoelectric transformers. The first one is a DC-DC converter that is based on a polyphase rectifier for isolated gate-drive power supply. The several phases available at the output allows for the generation of the supply for numerous drivers. The second one is a DC-AC converter similar to a matrix converter. The combination of the phases at the output of the TWPT allows for generation an AC signal at any frequency
20
Stekke, Jordan. "Contribution au perfectionnement de transformateurs pièzoélectriques dédiés à la génération de plasma froid pour applications biomédicales." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0065.
Full textAbstract:
Face à l’évolution de notre compréhension des plasmas froids, leur spectre d’exploitation n’a cessé de croître durant ces dernières décennies. Même si dans le domaine biomédical, l'intérêt s'est aujourd'hui étendu à applications diverses telles que la thérapie cellulaire, le soin des plaies, la chirurgie dentaire ou le traitement cornéen, la désinfection par plasma froid reste un sujet d’étude prépondérant dans le domaine. De nombreux générateurs plasma ont été développés dans le but de répondre aux exigences de désinfection des outils thermosensibles ou chimiosensibles. De nombreuses difficultés telles qu'un niveau de désinfection élevé, une durée de traitement minimale, un rapport de forme ou une géométrie complexe des outils doivent être prises en compte. Leur caractéristique commune est la nécessité d'une source de haute tension en entrée. Elle se justifie par l’obligation d'atteindre la valeur de tension de claquage du gaz de plusieurs kVolts. Dans certaines applications, cette source de haute tension peut représenter un problème de sécurité pour les personnes (choc électrique) et les appareils électriques (interférences électromagnétiques)With the evolution of our understanding of cold plasmas, their spectrum of exploitation has continued to increase over the past decades. Even if in the biomedical field, the interest has now extended to various applications such as cell therapy, wound care, dental surgery or corneal treatment, cold plasma disinfection remains a major subject of study in this field. Many plasma generators have been developed to meet the disinfection requirements of heat-sensitive or chemosensitive tools. Many difficulties such as a high level of disinfection, a minimum treatment time, a shape ratio or complex tool geometry must be taken into account. Their common feature is the need for a high voltage input source. It is justified by the obligation to reach the gas breakdown voltage value of several kVolts. In some applications, this high voltage source can be a safety problem for people (electric shock) and electrical equipment (electromagnetic interference)
21
Barham, Oliver M. "Microfabricated Bulk Piezoelectric Transformers." Thesis, University of Maryland, College Park, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10615552.
Full textAbstract:
Piezoelectric voltage transformers (PTs) can be used to transform an input voltage into a different, required output voltage needed in electronic and electro- mechanical systems, among other varied uses. On the macro scale, they have been commercialized in electronics powering consumer laptop liquid crystal displays, and compete with an older, more prevalent technology, inductive electromagnetic volt- age transformers (EMTs). The present work investigates PTs on smaller size scales that are currently in the academic research sphere, with an eye towards applications including micro-robotics and other small-scale electronic and electromechanical sys- tems. PTs and EMTs are compared on the basis of power and energy density, with PTs trending towards higher values of power and energy density, comparatively, indicating their suitability for small-scale systems. Among PT topologies, bulk disc-type PTs, operating in their fundamental radial extension mode, and free-free beam PTs, operating in their fundamental length extensional mode, are good can- didates for microfabrication and are considered here. Analytical modeling based on the Extended Hamilton Method is used to predict device performance and integrate mechanical tethering as a boundary condition. This model differs from previous PT models in that the electric enthalpy is used to derive constituent equations of motion with Hamilton’s Method, and therefore this approach is also more generally applica- ble to other piezoelectric systems outside of the present work. Prototype devices are microfabricated using a two mask process consisting of traditional photolithography combined with micropowder blasting, and are tested with various output electri- cal loads. 4mm diameter tethered disc PTs on the order of .002cm
3 , two orders smaller than the bulk PT literature, had the followingperformance: a prototype with electrode area ratio (input area / output area) = 1 had peak gain of 2.3 (± 0.1), efficiency of 33 (± 0.1)% and output power density of 51.3 (± 4.0)W cm
-3 (for output power of80 (± 6)mW) at 1M? load, for an input voltage range of 3V-6V (± one standard deviation). The gain results are similar to those of several much larger bulk devices in the literature, but the efficiencies of the present devices are lower. Rectangular topology, free-free beam devices were also microfabricated across 3 or- ders of scale by volume, with the smallest device on the order of .00002cm
3 . These devices exhibited higher quality factorsand efficiencies, in some cases, compared to circular devices, but lower peak gain (by roughly 1/2 ). Limitations of the microfab- rication process are determined, and future work is proposed. Overall, the devices fabricated in the present work show promise for integration into small-scale engi- neered systems, but improvements can be made in efficiency, and potentially voltage gain, depending on the application
22
Syed, Ehson Muhammad. "Analysis and modeling of piezoelectric transformers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63031.pdf.
Full text
23
Kahalerras, Mohamed Khaled. "Caractérisation des matériaux piézoélectriques dédiés à la génération des décharges plasmas pour applications biomédicales." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0019/document.
Full textAbstract:
Les transformateurs piézoélectriques se positionnent aujourd'hui comme une alternative technologique séduisante face aux solutions classiquement utilisées pour la génération des plasmas froids. Leur haute permittivité, leur faible tension d’alimentation et leur capacité de miniaturisation en font une solution sérieuse et originale pour de nombreuses applications faibles puissances, notamment dans le domaine biomédical pour la stérilisation, le traitement de surface et la décontami-nation des instruments médicaux. Dans le cadre d'un fonctionnement en générateur plasma, la conversion électromécanique au sein du transformateur s’accompagne de pertes mécaniques et diélectriques, souvent converties en chaleur. À ces effets s'ajoute l’influence proprement dite de la décharge sur le comportement électrique du dispositif. L’évolution dynamique et fortement non-linéaire de la décharge entraine un comportement méconnu des grandeurs électriques. Par conséquent, l’étage d’alimentation du transformateur constitue un sujet d’étude au même titre que le transformateur lui-même. De plus, étant donné la configuration du processus de génération, qui positionne le matériau piézoélectrique comme source et siège de la décharge plasma, il devient nécessaire d’analyser la viabilité du dispositif. L’ionisation du milieu gazeux environnant le générateur provoque des effets électroniques complexes, susceptibles d’entrainer des dépôts de matière à la surface du matériau ou d’en éroder la surface. C’est dans ce cadre, à l’interface entre le génie électrique et la science des matériaux, que s’articule cette thèse. Une première partie est destinée au développement d’un outil de commande numérique du générateur par une boucle de verrouillage de phase, assurant sa continuité de fonctionnement face aux variations des conditions opératoires. Par la suite, une modélisation du générateur plasma dans des configurations proches des décharges à barrières diélectriques est effectuée ;des simulations permettent une estimation de la puissance de décharge à partir d’une identification expérimentale des paramètres du modèle. Dans un deuxième temps, nous cherchons à établir une corrélation entre la structure du matériau et ses propriétés électriques en s’appuyant sur une méthodologie de caractérisation multi-échelle, avant et après décharge plasma. L'étude se focalise principalement sur l'évolution en surface de la structure cristalline et la composition chimique, en liaison avec les propriétés fonctionnelles du transformateur après génération de la décharge. Enfin, une étude en température porte sur l’investigation des effets d’auto-échauffement du générateur dans ce mode de fonctionnementDue to intensive development efforts during the past decade, piezoelectric transformers havebecome an attractive alternative solution compared to the con-ventionally used technologies forcold plasma generation. Their high efficiency, thin-shaped dimensions and low voltage supplymake them serious and original candidates for numerous low power applications, particularly inbiomedical field. Operating as a plasma generator, the electromechanical conversion within thetransformer is accompanied by mechanical and dielectric losses, often converted into heat. On topof these effects, the discharge is likely to influence the electrical behavior of the device. Thedynamic and highly non-linear evolution of the dis-charge leads to an unknown behavior ofelectrical properties. Consequently, the transformer supply stage is an active research subject inthe same way as the trans-former itself. Moreover, considering the configuration of the generationprocess, which positions the piezoelectric material as the source and the spot of the plasmadischarge, it becomes necessary to consider the viability of the device. The ioniza-tion of thegaseous environment surrounding the generator causes complex elec-tronic effects, which canlead to material deposition on the surface of the generator and thus modify or even degrade it. It iswithin this framework, at the interface between electrical engineering and material science, thatthis thesis is articulated. A first part is intended to develop a setup for numerical control of thedevice using a digital phase-locked loop to ensure its continuous operation in different operatingconditions. Subsequently, a model of the plasma generator in configurations close to dielectricbarrier discharges is proposed; Simulations allow an estimation of the discharge power from anexperimental identification of the model parameters. In a second part, we seek to establish acorrelation between the material structure and its electrical properties based on a multi-scalecharacterization methodology, before and after plasma discharge. The study focuses mainly onthe surface evolution in terms of the crystalline structure and the chemical composition, related tothe over-all properties of the piezoelectric transformer before and after discharge generation.Finally, a temperature study that concerns the investigation of the effects of self-heating of thegenerator in this operating mode is performed
24
Castro, Bruno Albuquerque de [UNESP]. "Localização de descargas parciais em transformadores de potência por meio de sensores piezelétricos de baixo custo e sistemas inteligentes." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/138944.
Full textAbstract:
Submitted by Bruno Albuquerque de Castro null (bruno.castro@feb.unesp.br) on 2016-06-01T17:52:34Z
No. of bitstreams: 1
Bruno_Albuquerque_de_Castro_MestradoEE.pdf: 3788528 bytes, checksum: 28b69717116921fa999eda08254ac160 (MD5)Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-06-02T19:10:47Z (GMT) No. of bitstreams: 1 castro_ba_me_bauru.pdf: 3788528 bytes, checksum: 28b69717116921fa999eda08254ac160 (MD5)
Made available in DSpace on 2016-06-02T19:10:47Z (GMT). No. of bitstreams: 1 castro_ba_me_bauru.pdf: 3788528 bytes, checksum: 28b69717116921fa999eda08254ac160 (MD5) Previous issue date: 2016-05-25
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O monitoramento e a localização precoce de descargas parciais em aparelhos de alta tensão, como nos transformadores de potência, são de fundamental importância para a prevenção de problemas funcionais associados à degradação contínua dos materiais que compõe o isolamento elétrico destes tipos de aparelho. Alguns fatores críticos na operação dos transformadores, como o funcionamento em sobrecarga, superaquecimento, transitórios e sinais elétricos de grande conteúdo harmônico vinculados a sistemas chaveados, em longo prazo, fazem com que o sistema de isolação de um transformador apresente degradação de suas propriedades físicas e químicas intrínsecas aos diversos tipos de materiais utilizados para esta finalidade e, deste modo, surjam descargas parciais. Este trabalho teve como objetivo aplicar sensores piezelétricos de baixo custo para a identificação e localização de descargas parciais em transformadores de potência por meio de sistemas inteligentes do tipo Redes Neurais e sistema de inferência neuro fuzzy adaptativos. Ambos os sistemas foram treinados com algumas métricas de processamento de sinais e os resultados de erro médio de localização chegaram na casa dos milímetros. Variou-se o número de sensores acoplados e foi realizado um estudo sobre os resultados de localização obtidos.
Partial discharge damages in power transformers require high cost monitoring procedures based on corrective maintenance or even interruptions of the power system. The development of online non-invasive monitoring systems to detect partial discharges in power transformers has great relevance since it can reduce significant maintenance costs. Some critical factors in the operation of transformers such as overload, nonlinear loads, transient voltage surges by atmospheric origin and switching, can make the insulation system of transformers to lose their physical and chemical properties. Therefore, these operating conditions can cause early deterioration of the insulation, causing internal partial discharges that may develop into major defects and thus shorten the useful life of electrical equipment. This research aimed to apply a low cost piezoelectric sensors for partial discharge identification and location in power transformers through intelligent systems such as neural networks and adaptive fuzzy inference system. Both systems were trained with some signal processing metrics and the results for location error was in the region of millimeters. It was varied the number of coupled sensors and a study was conducted on the obtained location results.
25
Khanna, Mudit. "Design of DC-DC converters using Tunable Piezoelectric Transformers." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/86442.
Full textAbstract:
This thesis introduces the ‘tunable’ piezoelectric transformers (TPT) which provide an extra control terminal, used in this case, to regulate the output voltage. A detailed mathematical analysis is done on the electrical equivalent circuit of the TPT to understand the effect of control terminal loading on the circuit performance. Based on this analysis, a variable capacitor connected across the control terminal is proposed to regulate the output voltage for line and load variations is suggested. The concept of ‘tunability’ in a TPT is introduced and mathematical conditions are derived to achieve the required ‘tunability’. This analysis can help a TPT designer to design the TPT for a specific application and predict the load and line regulations limits for a given design.
A circuit implementation of the variable capacitor, intended for control, is presented. With the proposed control circuit design, the effective value of a fixe capacitor can be controlled by controlling the duty cycle of a switch. Hence, this enables pulse width modulated (PWM) control for the TPT based converter operating at a constant frequency. Fixed frequency operation enables a high efficiency operation of TPT near its resonant frequency and the complete secondary control requires no isolation in the voltage feedback and control circuit. This prevents any ‘cross-talk’ between primary and secondary terminals and reduces the component count. The design of series input inductor for achieving zero voltage switching (ZVS) in the inverter switches for the new control is also discussed.
Experimental results for two different TPT designs are presented. Their differences in structure and its effect on the circuit performance has been discussed to support the mathematical analysis.Master of Science
26
Goenaga, Ekaitz. "Conception d’alimentations de puissance d’actionneurs piézo-électriques, avec et sans contact électrique, pour la génération des vibrations mécaniques." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENT103/document.
Full textAbstract:
Les travaux de thèse présentés dans ce manuscrit portent sur l’alimentation d’actionneurs de type piézo-électrique qui seront placés sur la partie tournante d’une perceuse. Ces actionneurs possèdent un comportement capacitif et sont habituellement alimentés par des systèmes linéaires. Une étude de dimensionnement et de conception a été menée sur différents amplificateurs à découpage qui peuvent fournir, dans un repère fixe, un signal de puissance sinusoïdal à fréquence variable dans les meilleures conditions possibles (rendement et THD). Ensuite, un système pouvant transférer l’énergie sans contact à l’actionneur piézo-électrique placé sur un repère tournant a été analysé. Cela a été possible grâce à l’utilisation des systèmes à induction, c’est-à-dire, par couplage magnétique à travers un transformateur tournant présentant un entrefer. Trois types de systèmes de transfert d’énergie sans contact ont été étudiés : l’un qui travaille à la fréquence de l’actionneur [50-500 Hz] et deux autres basés sur des stratégies de résonance permettant ainsi de diminuer les dimensions du coupleur magnétique. Pour cela, la modélisation tant magnétique qu’électrique a été effectuée dans les trois systèmes.Un prototype d’onduleur en pont complet fournissant jusqu’à 680 VAR a été réalisé. Ce dernier est placé en amont d’un coupleur magnétique basse fréquence transférant 1,75 kVAR à l’actionneur piézo-électrique en rotation. Les résultats obtenus en pratique ont montré la pertinence du travail de dimensionnement et conceptionPlaced on the rotating part of a drilling system. These actuators have a capacitive behavior and are usually supplied by linear systems. In this case, the design and the sizing of different switching amplifiers that provide, in a fixed frame, a sinusoidal power signal with modular frequency in the best possible conditions (efficiency and THD) have been made. Then, a contactless power system for piezoelectric actuators placed in a rotating frame was analyzed. This was possible thanks to the use of induction systems through a rotating transformer with an air gap. Three types of contactless systems were studied. The first one works at modular low frequencies [50-500 Hz] and the other two use resonant strategies in order to reduce transformer’s size. For this, both magnetic and electrical modeling was performed in the three cases.A full-bridge inverter prototype that can deliver up to 680 VAR and a low frequency contactless energy transfer system of 1.75 kVAR that supplies the piezoelectric actuator at rotating frame have been made. Experimental results showed satisfactory results and proved the system feasibility
27
Machado, Claiton Mainardi. "Análise de transformador piezelétrico radial utilizando disco de eletrodo seccionado para conversor half-bridge." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/8579.
Full textAbstract:
This work presents an analysis of a Piezoelectric Transformer (TP), showing the main types of devices, characteristics, operation modes, among others important points. The parameters of Mason Classic Model are determined by frequency response analysis. The nominal load is determined considering the maximum power transfer and the efficiency from the load tests. In order to obtain a more accurate equivalent model, an optimization methodology of equivalent model is proposed. The criterion used to optimize the model is the minimum standard square error between frequency response of TP and model. To prove the results obtained by the optimization meth-odology, it is presented, in impedance graphs, the curves of model obtained by fre-quency response, optimized model and TP. The optimized model is obtained for dif-ferent segments configurations of TP. The analysis of segments has the goal to adapt the TP to specific applications, enabling the parameters adjust, to different condi-tions of load impedance to maximum power transfer, voltage gain and efficiency, among others. The Half-Bridge practical results with nominal load are presented to all segments configurations, using as resonant converter.Este trabalho apresenta uma análise sobre Transformador Piezelétrico (TP), mostrando os principais tipos de dispositivos, características, modos de operação, en-tre outros pontos importantes. Os parâmetros do modelo clássico de Mason são de-terminados pela análise da resposta em frequência. A carga nominal é determinada levando em conta a máxima transferência de potência e o rendimento a partir de tes-tes de carga. Para obter o modelo equivalente mais preciso é proposto uma metodolo-gia de otimização do modelo equivalente. O critério utilizado para otimizar o modelo é do menor erro quadrático normalizado e ponderado entre a resposta em frequência do modelo e a resposta experimental do TP. Para comprovar os resultados obtidos pela metodologia de otimização, são apresentados gráficos de resposta em frequência do modelo obtido pela resposta em frequência, do modelo otimizado e a resposta ex-perimental do TP. O modelo otimizado é estendido para diferentes configurações de segmentos do TP. A análise dos segmentos tem como objetivo adequar o TP para aplicações específicas, possibilitando o ajustes de parâmetros, para diferentes condi-ções de resistência de carga para máxima transferência de potência, ganho de tensão e rendimento, entre outros. Resultados práticos com carga nominal são apresentados para todas configurações de segmentos, utilizando como conversor ressonante o con-versor Half-Bridge.
28
Horsley, Edward Lewis. "Modelling and analysis of radial mode piezoelectric transformers and inductor-less resonant power converters." Thesis, University of Sheffield, 2011. http://etheses.whiterose.ac.uk/12870/.
Full textAbstract:
Within the electronics industry there is a continual demand for DC-DC power converters that achieve high power density at low cost. Since a piezoelectric transformer (PT) has an electrical equivalent circuit that is similar to several resonant converter topologies, a PT can be used to replace many of the reactive components in these topologies with a single ceramic component, thereby offering potential savings in cost, size, and mass. The first part of this thesis presents a new equivalent circuit model for one of the most promising types of PT, the radial mode Transoner. This model relates the electrical characteristics of the PT to the physical dimensions and material properties. Considerable insight is then gained about how to design these devices to meet a particular set of converter specifications whilst simultaneously maximising PT power density. The second part of this thesis concerns the effect of the rectifier topology on PT power density. Using concepts from material science, together with equivalent circuit models of both the PT and the rectifier topologies, it is shown that a given PT will always achieve a higher thermally limited maximum output power when used in an AC-output topology compared to a DC-output topology. The half-bridge inductor-less PT-based converter topology is particularly attractive because it requires no additional components between the half-bridge and the rectifier. However, it is difficult to achieve zero-voltage-switching (ZVS) without significantly compromising PT power density when using this topology. The third part of this thesis details the development and experimental verification of a new model for the ZVS condition. Using a normalisation scheme and numerical optimisation techniques, the requirements for achieving inductor-less ZVS are accurately quantified for the first time. The impact of these requirements on PT power density is assessed, and design guidelines for maximising PT power density are given.
29
Nadal, Clément. "Contribution à la conception et la modélisation de transformateurs piézoélectriques dédiés à la génération de plasma." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2011. http://tel.archives-ouvertes.fr/tel-00621056.
Full textAbstract:
L'émergence des transformateurs piézoélectriques coïncident avec le développement dans les années 1950 des céramiques ferroélectriques appartenant à la famille cristalline des pérovskites qui n'ont cessé de s'améliorer depuis. Outre la compacité dont bénéficie ces structures, les transformateurs piézoélectriques offrent des performances remarquables en terme de gain en tension et rendement utiles pour des applications nécessitant une adaptation de tension ou une isolation galvanique, parfaitement dédiés aux applications de faibles puissances à haut rendement. Toutefois, les transformateurs piézoélectriques peuvent être déviés de leurs applications premières. En effet, la dernière décennie a été marquée par l'apparition de générateur de plasma par effet piézoélectrique utilisant principalement des architectures de type transformateur. Pourtant, si quelques applications usuelles illustrent parfaitement cette interaction, la compréhension des phénomènes physiques qui en sont à l'origine reste à approfondir. L'objectif de cette thèse est d'en expliquer les fondements par une approche méthodique. Ce travail s'articule autour de plusieurs étapes comprenant la mise en oeuvre d'une méthode systématique de la modélisation analytique d'un transformateur piézoélectrique, de l'étude de la carte de champ produit par un transformateur ainsi qu'une étude expérimentale vue des bornes en guise de premières investigations. La modélisation analytique est basée sur l'exploitation du Principe de Moindre Action (PMA). A partir de la théorie linéaire de la piézoélectricité, un modèle général applicable à toutes les géométries de transformateur, exploitant des modes de couplage piézoélectrique multiples, est proposé. Son caractère multimodal est par ailleurs mis en exergue. Cette modélisation est appliquée à une structure classique de transformateur piézoélectrique de type Rosen et les résultats obtenus sont validés d'une part par une identification numérique, issue d'un logiciel de calcul par éléments finis, et d'autre part par une caractérisation expérimentale. La modélisation analytique précédente ne tient pas compte dans sa mise en oeuvre de l'influence de l'environnement dans lequel évolue le transformateur piézoélectrique. Afin de caractériser le potentiel électrique produit, un modèle numérique 2D du champ électrique environnant est proposé selon la méthode des différences finies. Ce modèle est basé sur une extension du modèle analytique précédemment développé incluant les pertes mécaniques afin de quantifier le potentiel électrique de surface. Même si l'influence du plasma est négligée en première approximation, la modélisation permet de mettre en lumière les zones de fort champ correspondant aux zones de décharges luminescentes observées expérimentalement. Finalement, afin de valider le concept de générateur de plasma piézoélectrique, une caractérisation vue des bornes du transformateur piézoélectrique de type Rosen a été entreprise. Une étude systématique du déclenchement de la décharge plasma en fonction du niveau de tension et de la pression environnante a été menée. Cette part expérimentale de l'étude constitue une approche pionnière pour qualifier le comportement électromécanique du transformateur et a ainsi permis de mettre en évidence des comportements non linéaires issus de ce mode de fonctionnement atypique qu'est la génération de décharges de surface par effet piézoélectrique.
30
Martin, Thomas. "Contribution à l'étude des générateurs piézoélectriques pour la génération des décharges plasmas." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30117/document.
Full textAbstract:
Si l'utilisation des transformateurs piézoélectriques se bornait jusqu'alors à l'alimentation ou la protection de dispositifs électriques, ils sont aujourd'hui envisagés pour la génération de décharges plasma directement à leur surface. Les propriétés remarquables de ces générateurs piézoélectriques en font une alternative intéressante aux dispositifs conventionnels, notamment par la simplicité de mise en œuvre. La surface du transformateur constitue à la fois le support de décharge et l'élément élévateur de tension réduisant significativement l'encombrement des dispositifs. En outre les gains en tension de ces transformateurs sont remarquablement élevés et permettent d'obtenir des décharges pour des tensions d'alimentation n'excédant pas quelques volts. Ces avantages peuvent répondre avantageusement à certains problèmes rencontrés dans les procédés plasmas dont l'implantation dans les processus industriels, bien qu'elle soit en constante amélioration, est parfois confrontée à des problèmes de mise en œuvre d'enceintes complexes, rendant le procédé couteux ou inadapté aux conditions opératoires. L'objet de cette thèse porte sur l'étude fondamentale d'un transformateur piézoélectrique de type Rosen dédié à la génération de décharges électriques. Plus particulièrement, ce travail s'attèle au développement d'un modèle analytique permettant de mieux appréhender les limites de ce procédé innovant, ainsi qu'une meilleure compréhension du comportement des décharges plasma face aux spécificités de ce transformateur et de son matériau. Pour ce faire l'étude se consacre en première partie à la caractérisation du transformateur piézoélectrique hors décharge à partir de ses bornes, puis à l'extension d'un modèle analytique afin d'appréhender la distribution du potentiel électrique à sa surface. Le développement d'un dispositif expérimental permettra la mesure du potentiel ainsi que la discussion du modèle. Dans un second temps l'étude s'attache au comportement du transformateur piézoélectrique en décharge. La distribution de potentiel à présent connue constitue une donnée d'entrée nécessaire à l'étude de la dynamique de décharges dans ces différentes configurations. Les phénomènes à l'œuvre dans ce processus de génération étant complexes, l'étude est conduite suivant différentes étapes. Tout d'abord en passant par l'étude des propriétés des céramiques ferroélectriques au travers d'une décharge à barrière diélectrique plan-plan. Ensuite la dynamique des décharges est abordée par modélisation numérique suivant trois configurations différentes. Ces cas d'études conduisent à des régimes de décharges différents pouvant faire l'objet de mise en application future. Bien que le problème soit sous l'hypothèse d'un couplage faible, les résultats ont corroborés les observations expérimentales et ont permis de mieux comprendre l'influence des hautes permittivités et de la distribution du potentiel sur l'évolution spatio-temporelle de ce procédéNowadays piezoelectric transformers are not only used to supply or protect electrical devices, but also to generate plasma discharges directly on their surface. The remarkable properties of these piezoelectric generators make them an interesting alternative to conventional devices, especially the simple implementation. The surface of the transformer constitutes both the discharge support and the voltage elevator component reducing significantly the bulk of the devices. Besides the transformers' gain voltage are remarkably high and permit to generate discharges for low voltage supply not exceeding a few volts. These advantages respond to some problems met in the plasma processes of which the establishment in industrial processes - in constant improvement - is sometimes confronted to problems of chambers implementations, making this process expensive and not adequate to the operating conditions. The purpose of this thesis focuses on the fundamental studies of a Rosen piezoelectric transformer dedicated to the generation of electrical discharges. In particular, this work tackles the development of an analytical model allowing to improve the understanding of the limits of this innovating process, as well as a better comprehension of the plasma discharges behavior face with transformer and material features. In order to do this the first part of the study is devoted to the characterization of the piezoelectric transformer without discharge, then the extension of the analytical modeling in order to comprehend the distribution of surface electrical potential. The development of an experimental device will allow the potential measurement and the discussion of the model. In a second part the study focuses on behavior of the piezoelectric transformer in discharge. The potential distribution known today constitutes a necessary input data for the study of the discharge dynamic in different configurations. The complexity of the phenomena implemented in this process of generation requires to conduct the study following different steps. First of all, by the study of ferroelectric ceramic features through a dielectric-barrier discharge. Then the discharges dynamic is approached by numerical modeling following three different configurations. This cases conduct to different discharge regimes that can be the subject of future application. Even if the problem is under the hypothesis of a weak coupling, the results confirmed the experimental observations and permitted to understand better the influence of high permittivity and of the potential distribution on the saptio-temporal evolution of this process
31
Konchuba, Nicholas. "Temperature Compensation Improvements for Impedance Based Structural Health Monitoring." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/44455.
Full textAbstract:
Structural Health Monitoring is a useful tool for reducing maintenance costs and improving the life and performance of engineering structures. Impedance-Based SHM utilizes the coupled electromechanical behavior of piezoelectric materials to detect adverse changes and material and mechanical failures of structures. Environmental variables such as temperature present a challenge to assessing the veracity of damage detected through statistical modeling of impedance signals. An effective frequency shift method was developed to compensate impedance measurements for changes resulting from environmental temperature fluctuations. This thesis investigates how the accuracy of this method can be improved and be applied to a 100oF range of temperatures. Building up the idea of eliminating temperature effects from impedance measurements, this thesis investigates the possibility of using statistical moments to create a temperature independent impedance baseline.Master of Science
32
Nittayarumphong, Sadachai. "Vereinfachte Methoden zur optimalen Regelung resonanter Leistungskonverter." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231866555971-93803.
Full textAbstract:
Nowadays the developments of power supplies in military, industrial or commercial applications are growing rapidly, not only to achieve the highest efficiency but also to focus on the size and weight minimization which are playing a major role in this area. Therefore, the research trends in dc-dc, ac-dc, dc-ac, ac-ac topologies are still continuously developing into the direction of new topologies, new control concepts, new materials and devices to achieve highest efficiency and smallest size. The cost per unit is also one of the most important points of power supplies. Also, with new control methods and new ways of manufacturing, for example, the cost per unit might be reduced. Also, a simplified control concept might help to avoid discrete circuits, especially, at low power levels. The last mentioned statement is demonstrated, for instance, by the concept of the Link-Switch of the company Power Integration where an extremely small number of components are necessary. With the target of minimization, this research work explores the possibility to replace conventional electromagnetic transformers considered as the most bulky devices in power supplies by piezoelectric transformers (PT) for innovative off-line power supplies. Several control methods for a load resonant converter focusing on class-E topology utilizing PT, were developed in order to investigate and to select an appropriate control method capable of improving the efficiency and reducing the size of the converter. Efficiency should be understood in this way as maximum reliability at minimum power losses. Different controllers were evaluated for optimizing the effect of disturbances of line and load variations. The ZVS condition for a wide input voltage range and a wide output load range can be achieved by a method called duty-cycle tracking. Further, with an improved design of the PT containing an auxiliary tap, the ZVS condition can be obtained by a method called turn-on synchronization. The controlled output voltage, current or power is achieved by a variable frequency control. Further, the dynamic modeling for open loop and closed loop of load resonant converters, focused on the class-E topology, was introduced. The transient behavior of the output voltage of the open loop against perturbations such as the input voltage change, the switching frequency change, and the output load change is treated by replacing the complete circuit of the class-E converter by simple equivalent circuit models. The results from the analysis of the open loop dynamic behavior are applied to modeling the closed loop class-E converter with several control methods. The methods of linearization for exact solution and heuristic approximation for the steady state analysis were purposed. These models of linearization were implemented with the controller in its topologies to investigate the sufficient accuracy of obtained results of the regulation. Besides, the linearization models were used to observe the stability condition of the proposed control loops. Finally, the evaluation of a well-known classical control such P, I, PI, PD, PID and a simplified controller for a fixed load application by matching an appropriate switching frequency according to the input voltage, into the load resonant converter, considering class-E topology, were presented. Also, the optimum design of the controller for a load resonant converter was discussed and derivedDie Entwicklung von Stromversorgungen in militärischen, industriellen und kommerziellen Anwendungen nimmt bis heute tendenziell stark zu. Nicht nur zur Erzielung höchster Wirkungsgrade, sondern auch im Hinblick auf Baugrößen- und Gewichtsminimierung, welche eine vorrangige Rolle spielen, ist diese Tendenz zu verzeichnen. Diesbezüglich gehen die Forschungstrends bei DC-DC, AC-DC, DC-AC und AC-AC Topologien in Richtung neuer Topologien, neuer Regelungskonzepte, sowie neuer Materialien und Bauelemente, um den höchsten Wirkungsgrad bei kleinster Baugröße zu erreichen. Die Gerätekosten sind ebenso ein sehr wichtiger Punkt bei Stromversorgungen. Auch durch neue Regelungsmethoden und durch neue Herstellungsverfahren können die Gerätekosten beispielsweise reduziert werden. Ebenso kann ein vereinfachtes Regelungskonzept dazu verhelfen, dass diskrete Schaltungen, speziell im unteren Leistungsbereich, vermieden werden. Letzteres wird beispielsweise beim Konzept des Link-Switch der Firma Power Integration verdeutlicht, indem extern wenige Bauelemente benötigt werden. Mit dem Ziel der Miniaturisierung wird in dieser Forschungsarbeit die Möglichkeit untersucht, konventionelle elektromagnetische Transformatoren, welche in Stromversorgungen als besonders voluminös gelten, durch piezoelektrische Transformatoren (PT) bei der Herstellung innovativer Netzstromversorgungen zu ersetzen. Verschiedene Regelungsmethoden für Lastresonanzkonverter, mit dem Fokus auf eine Klasse- E-Topologie mit PT, wurden hierzu entwickelt. Dies hatte zum Ziel, ein geeignetes Regelungsverfahren zu erarbeiten und auszuwählen, welches eine verbesserte Effizienz bei reduzierter Konverter-Baugröße aufzuweisen hat. Effizienz soll hierbei verstanden werden als maximale Zuverlässigkeit bei minimalen Leistungsverlusten. Verschiedene Reglertypen wurden entworfen um die Effekte der Störungen durch Netzspannungs-und Lastvariationen regelungstechnisch zu optimieren. Die Nullspannungsschaltungsbedingung (ZVS-Bedingung) über einen weiten Bereich der Eingangspannung und einen weiten Lastbereich kann durch einen sogenannte Duty-Cycle-Nachführung mit der Frequenz erreicht werden. Weiterhin kann durch eine verbesserte Ausführung des PT auf Basis einer Hilfsanzapfung die ZVSBedingung durch eine sogenannte Einschaltsynchronisation erreicht werden. Geregelte Ausgangsspannung, Ausgangsstrom oder Ausgangsleistung werden über eine Frequenzstellung erreicht. Die dynamische Modellierung der offenen und geschlossenen Regelschleife eines Lastresonanzkonverters, wieder im Hinblick auf die Klasse-E, wird im weiteren vorgestellt. Das transiente Verhalten der Ausgangsspannung der offenen Regelschleife gegenüber Störungen durch Eingangsspannungsänderung, durch Schaltfrequenzänderung oder durch Ausgangslaständerung, wird durch den Ersatz der Klasse-E-Schaltung durch einfache Äquivalenzmodelle behandelt. Die Ergebnisse der Analyse des Verhaltens des offenenen Regelkreises werden verwendet, um den Klasse-E-Konverter mit geschlossener Regelschleife unter Verwendung verschiedener vorgestellter Regelungsmethoden zu modellieren. Methoden der Linearisierung für die exakte Lösung und für eine heuristische Approximation der statischen Analyse des eingeschwungenen Zustands werden vorgeschlagen. Diese Methoden der Linearisierung werden zusammen mit den Reglermodellen in deren jeweilige Topologie implementiert um die ausreichende Genauigkeit der erhaltenen Resultate des Regelungsverhaltens zu beurteilen. Weiterhin werden diese Linearisierungsmodelle dazu verwendet, die Stabilitätskriterien der vorgeschlagenen Regelschleife zu überwachen. Schlussendlich wird die Bestimmung der bekannten klassischen Regler (P, I, PI, PD, PID), sowie eines vereinfachten Konstantlaststellers durch geeignete Anpassung der Schaltfrequenz an die Eingangsspannung, für Lastresonanzkonverter, wieder mit Blick auf die Klasse-E, vorgestellt. Außerdem wird der optimierte Reglerentwurf für Lastresonanzkonverter diskutiert und abgeleitet
33
Engleitner, Raffael. "Análise estática normalizada e modelagem de pequenos sinais do conversor classe-e utilizando transformadores piezoelétricos." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/8495.
Full textAbstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorPiezoelectric transformers (PTs) allow the design of promising power supply applications, increasing efficiency, reducing size, facilitating the achievement of high transformation ratio, besides providing high immunity against electromagnetic noise. Due to the electrical equivalent model having resonant characteristics, some resonant topologies are naturally suitable for these power supplies, i.e. the Class- E, Half-Bridge, Full-Bridge and Push-pull. Among these topologies, the Class-E converter has a highlight of having one controlled switch. The static gain of the Class-E is changed through the switching frequency variation, while the duty cycle is adjusted with the purpose of achieving soft switching for different switching frequencies and loads. The analisys of this process becomes complex when the system has a high number of reactive elements. One way to simplify this analisys is applying a normalized methodology. On this regard, the first result of this work is the normalized analisys of the functionally of the Class-E converter, including normalized load and switching frequency variation. This allows choosing one optimum point for the static design, without the necessity of design parameters. The main objective of this analisys is the obtention of the duty cycle behavior in order to have soft switching for all operation points. In a second moment, a small-signal model was derived using the generalized averaging method, through Fourier series aproximation. The model describes the relevant poles and zeros of the system, being accurate enough for different loads and switching frequencies. The behavior of resonant converters changes considerably for different operating points; therefore it is important to have a model that represents the system well. The normalized analisys allowed simplifying the small-signal model derivation, once soft switching is achieved for all the operation points. Experimental measurements validate either the normalized or the small signal derivation methodologies. The measurements were achieved for a 3W step-down converter, with universal 85-265 V AC input and 6 V DC output.
Os Transformadores Piezoelétricos (PTs) permitem o projeto de aplicações promissoras para fontes de alimentação até 100W, melhorando a eficiência, reduzindo o tamanho, facilitando a obtenção de grandes relações de transformação, além de proporcionar alta imunidade contra ruídos eletromagnéticos e interferências. Os PTs apresentam modelo elétrico ressonante, trazendo a necessidade de implementação juntamente com topologias de conversores ressonantes, como por exemplo os conversores: Classe-E, Meia Ponte, Ponte Completa e Push-pull. Dentre estas topologias, o conversor Classe-E se destaca por apresentar somente um interruptor controlado. O ganho estático do conversor Classe-E é obtido através da variação da freqüência de chaveamento, e a razão cíclica muda para atender as condições de comutação suave para diferentes freqüências e cargas. A análise deste processo se torna complexa à medida que o sistema apresenta inúmeros elementos reativos. Uma maneira de simplificar esta análise é utilizar uma metodologia normalizada. Devido a isso, o primeiro resultado deste trabalho é a análise normalizada do funcionamento do conversor piezoelétrico Classe- E, incluindo variação normalizada da frequênciade operação e da carga. Isso permite escolher um ponto ótimo de projeto estático, sem a necessidade de parâmetros de projeto. O objetivo principal desta análise normalizada é a obtenção do comportamento da razão cíclica para obter comutação suave em todos os pontos de operação. Em um segundo momento, um modelo de pequenos sinais foi derivado utilizando a metodologia do modelo médio generalizado, através de aproximação por series de Fourier. O modelo descreve os pólos e zeros relevantes do sistema, sendo suficientemente preciso para diferentes cargas e da frequencias de operação. O comportamento de conversores ressonantes varia consideravelmente para diferentes pontos de operação, pois isso um modelo que permita avaliar estes pontos de maneira precisa se faz importante. A análise normalizada permitiu simplificar a derivação do modelo de pequenos sinais, uma vez que garante a operação em comutação suave. Para validar a metodologia apresentada, são mostrados resultados experimentais para um conversor abaixador de 3W, entrada universal de 85-260 V AC e saída de 6 V DC.
34
Nittayarumphong, Sadachai. "Vereinfachte Methoden zur optimalen Regelung resonanter Leistungskonverter." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23833.
Full textAbstract:
Nowadays the developments of power supplies in military, industrial or commercial applications are growing rapidly, not only to achieve the highest efficiency but also to focus on the size and weight minimization which are playing a major role in this area. Therefore, the research trends in dc-dc, ac-dc, dc-ac, ac-ac topologies are still continuously developing into the direction of new topologies, new control concepts, new materials and devices to achieve highest efficiency and smallest size. The cost per unit is also one of the most important points of power supplies. Also, with new control methods and new ways of manufacturing, for example, the cost per unit might be reduced. Also, a simplified control concept might help to avoid discrete circuits, especially, at low power levels. The last mentioned statement is demonstrated, for instance, by the concept of the Link-Switch of the company Power Integration where an extremely small number of components are necessary. With the target of minimization, this research work explores the possibility to replace conventional electromagnetic transformers considered as the most bulky devices in power supplies by piezoelectric transformers (PT) for innovative off-line power supplies. Several control methods for a load resonant converter focusing on class-E topology utilizing PT, were developed in order to investigate and to select an appropriate control method capable of improving the efficiency and reducing the size of the converter. Efficiency should be understood in this way as maximum reliability at minimum power losses. Different controllers were evaluated for optimizing the effect of disturbances of line and load variations. The ZVS condition for a wide input voltage range and a wide output load range can be achieved by a method called duty-cycle tracking. Further, with an improved design of the PT containing an auxiliary tap, the ZVS condition can be obtained by a method called turn-on synchronization. The controlled output voltage, current or power is achieved by a variable frequency control. Further, the dynamic modeling for open loop and closed loop of load resonant converters, focused on the class-E topology, was introduced. The transient behavior of the output voltage of the open loop against perturbations such as the input voltage change, the switching frequency change, and the output load change is treated by replacing the complete circuit of the class-E converter by simple equivalent circuit models. The results from the analysis of the open loop dynamic behavior are applied to modeling the closed loop class-E converter with several control methods. The methods of linearization for exact solution and heuristic approximation for the steady state analysis were purposed. These models of linearization were implemented with the controller in its topologies to investigate the sufficient accuracy of obtained results of the regulation. Besides, the linearization models were used to observe the stability condition of the proposed control loops. Finally, the evaluation of a well-known classical control such P, I, PI, PD, PID and a simplified controller for a fixed load application by matching an appropriate switching frequency according to the input voltage, into the load resonant converter, considering class-E topology, were presented. Also, the optimum design of the controller for a load resonant converter was discussed and derived.Die Entwicklung von Stromversorgungen in militärischen, industriellen und kommerziellen Anwendungen nimmt bis heute tendenziell stark zu. Nicht nur zur Erzielung höchster Wirkungsgrade, sondern auch im Hinblick auf Baugrößen- und Gewichtsminimierung, welche eine vorrangige Rolle spielen, ist diese Tendenz zu verzeichnen. Diesbezüglich gehen die Forschungstrends bei DC-DC, AC-DC, DC-AC und AC-AC Topologien in Richtung neuer Topologien, neuer Regelungskonzepte, sowie neuer Materialien und Bauelemente, um den höchsten Wirkungsgrad bei kleinster Baugröße zu erreichen. Die Gerätekosten sind ebenso ein sehr wichtiger Punkt bei Stromversorgungen. Auch durch neue Regelungsmethoden und durch neue Herstellungsverfahren können die Gerätekosten beispielsweise reduziert werden. Ebenso kann ein vereinfachtes Regelungskonzept dazu verhelfen, dass diskrete Schaltungen, speziell im unteren Leistungsbereich, vermieden werden. Letzteres wird beispielsweise beim Konzept des Link-Switch der Firma Power Integration verdeutlicht, indem extern wenige Bauelemente benötigt werden. Mit dem Ziel der Miniaturisierung wird in dieser Forschungsarbeit die Möglichkeit untersucht, konventionelle elektromagnetische Transformatoren, welche in Stromversorgungen als besonders voluminös gelten, durch piezoelektrische Transformatoren (PT) bei der Herstellung innovativer Netzstromversorgungen zu ersetzen. Verschiedene Regelungsmethoden für Lastresonanzkonverter, mit dem Fokus auf eine Klasse- E-Topologie mit PT, wurden hierzu entwickelt. Dies hatte zum Ziel, ein geeignetes Regelungsverfahren zu erarbeiten und auszuwählen, welches eine verbesserte Effizienz bei reduzierter Konverter-Baugröße aufzuweisen hat. Effizienz soll hierbei verstanden werden als maximale Zuverlässigkeit bei minimalen Leistungsverlusten. Verschiedene Reglertypen wurden entworfen um die Effekte der Störungen durch Netzspannungs-und Lastvariationen regelungstechnisch zu optimieren. Die Nullspannungsschaltungsbedingung (ZVS-Bedingung) über einen weiten Bereich der Eingangspannung und einen weiten Lastbereich kann durch einen sogenannte Duty-Cycle-Nachführung mit der Frequenz erreicht werden. Weiterhin kann durch eine verbesserte Ausführung des PT auf Basis einer Hilfsanzapfung die ZVSBedingung durch eine sogenannte Einschaltsynchronisation erreicht werden. Geregelte Ausgangsspannung, Ausgangsstrom oder Ausgangsleistung werden über eine Frequenzstellung erreicht. Die dynamische Modellierung der offenen und geschlossenen Regelschleife eines Lastresonanzkonverters, wieder im Hinblick auf die Klasse-E, wird im weiteren vorgestellt. Das transiente Verhalten der Ausgangsspannung der offenen Regelschleife gegenüber Störungen durch Eingangsspannungsänderung, durch Schaltfrequenzänderung oder durch Ausgangslaständerung, wird durch den Ersatz der Klasse-E-Schaltung durch einfache Äquivalenzmodelle behandelt. Die Ergebnisse der Analyse des Verhaltens des offenenen Regelkreises werden verwendet, um den Klasse-E-Konverter mit geschlossener Regelschleife unter Verwendung verschiedener vorgestellter Regelungsmethoden zu modellieren. Methoden der Linearisierung für die exakte Lösung und für eine heuristische Approximation der statischen Analyse des eingeschwungenen Zustands werden vorgeschlagen. Diese Methoden der Linearisierung werden zusammen mit den Reglermodellen in deren jeweilige Topologie implementiert um die ausreichende Genauigkeit der erhaltenen Resultate des Regelungsverhaltens zu beurteilen. Weiterhin werden diese Linearisierungsmodelle dazu verwendet, die Stabilitätskriterien der vorgeschlagenen Regelschleife zu überwachen. Schlussendlich wird die Bestimmung der bekannten klassischen Regler (P, I, PI, PD, PID), sowie eines vereinfachten Konstantlaststellers durch geeignete Anpassung der Schaltfrequenz an die Eingangsspannung, für Lastresonanzkonverter, wieder mit Blick auf die Klasse-E, vorgestellt. Außerdem wird der optimierte Reglerentwurf für Lastresonanzkonverter diskutiert und abgeleitet.
35
Yeh, Yu-Chung, and 葉俞均. "Piezoelectric Ceramics Transformer." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/21807343980157655421.
Full textAbstract:
碩士國立中央大學
光電科學研究所
92
Along with the invention of piezoelectric ceramic, there were many other small-sized but highly efficiency- transformed devices being researched and developed since then. In order to reduce the volume of power supplies and raise its efficiency simultaneously, researchers use piezoelectric transformers made by piezoelectric ceramic to serve their purpose. This thesis focuses in the piezoelectricity of piezoelectric ceramic, how to motivate a piezoelectric transformer, and how to use piezoelectric transformers to drive the backlight source.
36
Huang, Chun-Chang, and 黃俊彰. "New Type Piezoelectric Transformer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/20482093145977868791.
Full text
37
Chen, Chi-Shao, and 陳奇劭. "Clamped-Clamped Beam Type Piezoelectric Transformer." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/77019191137393169214.
Full textAbstract:
碩士中興大學
機械工程學系所
99
In this paper, we study the piezoelectric transformers in a form of fixed-fixed beam. And an analytical solution of a fixed-fixed beam type piezoelectric transformer with Euler-Bernoulli beam assumption is proposed. The electromechanical equations are first derived for transient motions, and coupled expressions for the mechanical response and voltage output are obtained. The resulting equations are further reduced for the case of excitation around the first resonance frequency. Analyical solutions of mechanical response, voltage, current, and power outputs are presented. From our analytical model, output voltage depends on the lengths of two electrodes, the Young’s modulus ratio and thickness ratio between PZT layer and substrate, but is constant with respect to the length of beam. Besides, the lengths of input electrodes should be 0.22 times the length of beam to achieve the largest output from the largest moment. Furthermore, when the transformer is excited at first resonant frequency higher output voltage can be obtained with the shorter output electrodes. The resoance frequency using to excite the transformer are inversely proportional to the square of the lengthe of beams, so we can control the working frequency by the length of beam. The combination of Young’s modului and thicknesses of PZT layer and substrate change the position of netural axis and the bending stiffness of beam, concurrently. However, output voltages of transformers depend not only on the postion of neutral axes but also on bending stiffnesses. The result is the transformer can get better performance by using the substrate with higher Young’s modului We also use the finite element methods and the experiment to verify the analytical model. Finally, the error of output voltage between the analytical model and experiment is less 10%.
38
Liao, Yen-hsun, and 廖彥勛. "Study of Disk Type Piezoelectric Transformer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/28691082576643108317.
Full textAbstract:
碩士義守大學
電機工程學系碩士班
97
A new matrix method is proposed in this study to investigate transformation characteristics of a thin disk-type piezoelectric transformer, which consists of two electric ports and one insulating region between them. The transmission matrix for each region is derived from the corresponding piezoelectric equations, which can be constructed using the corresponding governing equations and appropriate constitutive relations. The resultant transmission matrix of the piezoelectric transformer is obtained via the multiplication of each transmission matrix. By enforcing the boundary conditions at interfaces, the admittance matrix of the piezoelectric transformer is formulated. The voltage gain and power efficiency of the piezoelectric transformer connected to arbitrary load impedances with different electrode area ratios are demonstrated. Several disk-type piezoelectric transformers were fabricated and measured in this work. Simulation results calculated using the transmission matrix method and the finite element method are presented along with the experimental data. Comparison results show good agreements. Results obtained in this work can be employed for the design of disk-type piezoelectric transformers.
39
Jun-Ching, Lee, and 李俊慶. "Self-Resonant Backlight Inverter Using Piezoelectric Transformer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/88322585152039738795.
Full textAbstract:
碩士國立臺灣大學
電機工程學研究所
91
Comparing with electromagnet transformer, piezoelectric transformer has the advantages of small volume and high power density. In order to achieve maximum efficiency, its control circuit often is very complex. This thesis uses delicate self-resonant circuit to solve circuit components aging problem and its efficiency can achieve 76%. Cold cathode fluorescent lamp has highest efficiency in sinusoidal wave. Traditional Royer converter has the advantages of outputting sinusoidal wave、 few components、and high efficiency. As a result, it is often used in industry. However, it always needs to sacrifice lighting efficiency to increase electric circuit efficiency. Second serious problem is that different layout and different package will introduce different parasitic capacitance even in the same circuit. Because lamp’s voltage is very high, the parasitic capacitance will cause a lot of loss. This loss even can not be anticipated in advance. Different kinds of situation will cause different effect. This thesis uses math model and experiments to prove that piezoelectric self-resonant circuit can improve these problem. Because piezoelectric parameter has close relationship with oscillating frequency and efficiency, it is hard to change, however. At last, this thesis uses math model and experiments to make output port in series or in parallel with capacitance. We try to use exterior electric component to change oscillating frequency without changing its mechanical structure.
40
Su, Sheng-Chi, and 蘇聖琪. "Phase Controlled Piezoelectric Transformer Using in Backlight Inverter." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/48551999388304857487.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
94
The backlight system is one of the most important parts in the liquid crystal display (LCD). It consumes most of the power of the whole system. To achieve higher power efficiency, piezoelectric transformers are utilized in the backlight systems. A piezoelectric transformer can be a high-efficiency power converter. Compared with a traditional electromagnetic transformer, it has many advantages such as lower electromagnetic interference (EMI), higher safety, and smaller volume. However, a piezoelectric transformer has the highest efficiency and the highest voltage gain only when it is operated around its resonant frequency. As a result, it is very important to maintain the operating frequency of a piezoelectric transformer. This thesis is focused on the application of the piezoelectric transformer in the backlight system. The relations between the phase difference of the input voltage and the output current, operating frequency, and voltage gain are discussed. A phase control strategy is also proposed. The control strategy uses the phase comparing with the input voltage signal and the input current signal to maintain the operating frequency of the piezoelectric transformer. We use the burst mode to regulate the brightness of the CCFL. We also ignite the CCFL and measure the efficiency in the experiment. The backlight system is one of the most important parts in the liquid crystal display (LCD). It consumes most of the power of the whole system. To achieve higher power efficiency, piezoelectric transformers are utilized in the backlight systems. A piezoelectric transformer can be a high-efficiency power converter. Compared with a traditional electromagnetic transformer, it has many advantages such as lower electromagnetic interference (EMI), higher safety, and smaller volume. However, a piezoelectric transformer has the highest efficiency and the highest voltage gain only when it is operated around its resonant frequency. As a result, it is very important to maintain the operating frequency of a piezoelectric transformer. This thesis is focused on the application of the piezoelectric transformer in the backlight system. The relations between the phase difference of the input voltage and the output current, operating frequency, and voltage gain are discussed. A phase control strategy is also proposed. The control strategy uses the phase comparing with the input voltage signal and the input current signal to maintain the operating frequency of the piezoelectric transformer. We use the burst mode to regulate the brightness of the CCFL. We also ignite the CCFL and measure the efficiency in the experiment.
41
Lin, Hui-Ya, and 林惠雅. "Design and Analysis of Rosen-Type Piezoelectric Transformer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/75663203636726979662.
Full textAbstract:
碩士中原大學
機械工程研究所
95
Abstract The recently developed piezoelectric ceramic transformer has the advantage of high power transmission efficiency produced in a small-scale structure. Compared with traditional magnetic transformer, they have completely different structure and made materials, and principle of voltage step-up ratio. In general, the piezoelectric ceramic transformer is of the advantages of small size, high conversion efficiency, high voltage step-up ratio, etc. It is widely used for the Cold Cathode Fluorescent Lamp source driver and is already obtained satisfactory performance in practical applications. In those different kinds of piezoelectric transformers, the most popular one is the Rosen type. In this article, the focus is on the structure (dimension) and its effect to the voltage step-up ratio for a Rosen-type piezoelectric transformer. Finite element simulation software ANSYS is used. Through the simulations results of output voltage, minimum displacement, stress value, three-dimensional modal analysis, and energy distribution, it concludes that the highest voltage step-up ratio operated with full wave resonance frequency; under no-load condition, the voltage step-up ratio increases as the ratio of length to width and the ratio of length to height increases; the voltage output increases for the resonant frequency becomes lower while the length increases, but the increasing degree becomes very small when the length increases to a level; the output voltage is a little bit higher for the length of the generator section is longer than the length of the driver section as compared to the equal length of the driver section and the generator section.
42
Fu, Ming-Yue, and 傅明宇. "Driving Circuit of Cold Cathode Fluorescent Lamp Employing Piezoelectric Transformer." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/69465759947316059021.
Full textAbstract:
碩士國立成功大學
電機工程學系
87
This thesis is based on the study and design of cold cathode fluorescent (CCFL) driver circuit by using series resonant parallel loaded circuit with Rosen-type piezoelectric transformer (PT). In the thesis, PT equivalent circuit and characteristics is introduced, also CCFL’s voltage to current characteristics will be found experimentally in order to derive the first order steady state equivalent circuit, also the use of PT characteristics to control the current through CCFL is mentioned. By using the PT’s and CCFL’s equivalent circuit with fixed voltage and current, the best capacitance and introduce can be derived, so that the current follow into CCFL is not too large or too small. Last of all from the design step by using fixed frequency control method the CCFL’s driving circuit using PT can be realized, and by using the pulse width modulation, to control PT input voltage such that CCFL’s brightness is controlled.
43
Lai, Yi-Ying, and 賴羿穎. "Study of Piezoelectric Transformer Fed Rectifiers for LED Lighting Module." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/11958921929916106259.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
100
The main purpose of this thesis is to compare three different topologies of LED drivers by using a piezoelectric transformer. There are several advantages in LEDs lighting applications, which include low profile, low power consumption, and high efficacy, etc. However, most LED drivers are based on the magnetic components, which may sacrifice the low profile advantage associated with LED lighting. On the other hand, the merits of the piezoelectric transformer are thin profile, high power density and no electromagnetic interference radiation when compared to electromagnetic transformers. Therefore, piezoelectric transformers are suitable to drive LEDs on this account. Since the output voltage of the piezoelectric transformer is highly related to the load impedance, the methods of designing the interface between the piezoelectric transformer and the LEDs are thus the key design parameters. Specifically, different interface methods lead to different temperature rise and vastly different efficiency. In this thesis, three methods are discussed in detail. They are LED self-rectifier circuit, full-wave rectifier and current doubler. Theoretical analysis of these three various topologies will be given first. Then, the theoretical prediction will be verified by the circuit simulator PSIM. Finally, the characteristics among these three driving methods will be summarized and compared. From the simulation and experimental results, utilizing the current doubler is much more suitable when the load is LED lighting module. By utilizing the current doubler rectifier, the output voltage, output current and efficiency is the highest when compared to the other two methods.
44
tayu, Hsu, and 徐達裕. "Study of Variable-Voltage Variable-Frequency Inverter Utilizing Piezoelectric Transformer." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/56400880160692196119.
Full textAbstract:
碩士國立成功大學
電機工程學系
88
In this thesis, piezoelectric transformers (PTs) are applied as frequency modulated device. The instant voltage of the reference input is designed to drive and control the frequency of PT, and the corresponding voltage gain of PT is decided by variable interval of the vibrational frequency. The amplitude of PT’s vibration will be equal to the expected instant output voltage of the VVVF (Variable frequency variable voltage) inverter. In an experiment we hope to use the digital synthesizer to produce a fundamental output, and the fundamental frequency will be equal to the expected frequency. Also the amplitude will be equal to the envelope voltage of the modulated frequency. The synchronous rectifier switches the instant modulating output in the ZVS form. Finally the harmonic component is filtered out by low pass filter and the fundamental sine wave is obtained.
45
Chen, Hong-Liang, and 陳宏亮. "Study of Step-Down Characteristics of Rosen-Type Piezoelectric Transformer." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/00331826750094567541.
Full textAbstract:
碩士國立成功大學
電機工程學系
89
In this thesis, we purpose to investigate the step-down characteristics and the converse driving technology. They are applied to implement a half bridge resonant adapter by step-up Rosen-type piezoelectric transformers(PT). First of all, one proofs the equivalent circuit model of Rosen-type PT which is applied in the converse operation from piezoelectric equations, and then analyzes the relations among the structure, the equivalent model and some characteristics of PT. The analyzed results show that the voltage gain, the output power, and the efficiency depend on the parameters of structure such as length, width, and thickness. Then we can scheme a PT design flow to fit the special requirements. According to the simulation and the equivalent model, one exercises three different size Rosen-type PTs accompanying with the half bridge resonant circuit and the rectifier circuit to realize the step-down adapter by converse-operation mode Rosen-type PT.
46
Chiu, Liang-Hsiang, and 邱良祥. "Study of DC-DC Converters Utilizing Annular-Type Piezoelectric Transformer." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/y298dn.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
90
When the piezoelectric transformer (PT) applies to DC-DC converters, it always uses thickness vibration mode PT for low impedance load. Because the structure and manufacture of the above-mentioned PT is complex and there are patent problems in business, this thesis adapts simpler Annular-Type PT in structure and manufacture to study DC-DC converters. First of all,the PT equivalent circuit and characteristics is introduced. And uses Spice and Matlab to simulate and analyze. Later it uses the half bridge resonant circuit to drive the PT. A control strategy for DC-DC converters based on phase detector circuit. The control always tracks transformer resonance frequency. Voltage regulation is achieved by adopting the pulse width modulation technique. Eventually, it will achieve the purpose of higher output efficiency.
47
Chen, Ya-Mei. "Development of a 3D Finite-Element Solver for Piezoelectric Transformer Analysis." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2907200410083600.
Full text
48
Sheng-Kai, Lin, and 林聖凱. "Realization Study of LCD Backlighting Source by Piezoelectric Transformer Energy Conversion." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/10373397262794161810.
Full textAbstract:
碩士國立臺灣科技大學
自動化及控制研究所
92
In this thesis, a backlighting source implemented by piezoelectric transformer as an energy inverter is proposed. The piezoelectric transformer is driven by a half-bridge series-resonant parallel-loaded inverter. Modeling piezoelectric transformer and cold-cathode fluorescent lamp for system analysis is conducted. A prototype of a half-bridge series-resonant inverter with piezoelectric transformer for driving a 1.6W and 2.8W cold-cathode fluorescent lamps is realized and examined. A dimming process is employed by frequency-modulation. The experimental result is close to the theoretical predictions.
49
Huang, Shou-ming, and 黃首鳴. "Frequency Feedback Control in Piezoelectric Transformer for Improving CCFL Illumination Stability." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/28176024877957165732.
Full textAbstract:
碩士國立成功大學
電機工程學系
88
In the thesis, the application of piezoelectric transformers (PTs) in the cold-cathode fluorescent lamp (CCFL) driver circuit with closed-loop frequency control is studied. First, the method of obtaining PT’s electrical equivalent model is discussed. Then with the assistance of MCAD, the equivalent values are calculated. The CCFL characteristics and its negative resistance modeling will also be discussed. Then by using PT’s desirable properties, the CCFL driver circuit is implemented to improve illumination stability of CCFL. With the control of operation frequency the dimming control of CCFL is achieved. The comparison of variable frequency and constant frequency feedback control of the CCFL driver will be mentioned. Finally the realization of the variable frequency feedback control employing PT in CCFL driver circuit is introduced and discussed in detail.
50
Ho, Chung-Chun, and 何忠駿. "Design of High Power ZVS Piezoelectric Transformer and Current Balance Structure." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66148175660807273214.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
97
Driving paralleled T5 lamps with disk-type piezoelectric transformers (PT) is the main focus of this thesis. Two kinds of piezoelectric transformer were designed and studied in this thesis. The first one is a single output disk-type piezoelectric transformer which is used with current balanced circuit. The second one is a four output disk-type piezoelectric transformer. Although the second kind is more complex, it can drive four paralleled T5 14W lamps directly without any current balance circuit. The purpose of this research is to substitute conventional electromagnetic ballasts with electronic ballasts using a piezoelectric transformer and driving multiple paralleled T5 lamps. Although the design of driving multiple paralleled lamps is more difficult to design, it could significant lower the cost of ballasts. The power range of piezoelectric transformer based ballast was about 10~20W before, but the power of the disk type piezoelectric transformer in this paper can reach 52.8W. This thesis also analyzes the electronic characteristics with equivalent circuit of piezoelectric transformer with the two-ports network model. The impedance matching point was derived from equivalent circuit model. To achieve Zero voltage switching (ZVS) condition is one of the main focus in this thesis. To achieve the ZVS condition, a small inductor was series inserted in front of piezoelectric transformer. The optimal value of the small inductor is decided by the resonant frequency of the PT. Specifically, the resonant frequency resonant tank composed of the small inductor and the input intrinsic capacitor of the piezoelectric transformer should be set between one to three times of resonance of piezoelectric transformer. A ZVS inverter based on disk-type piezoelectric transformer has been implemented. The result showed that two kinds of piezoelectric transformers can both light up four T5 14W fluorescent lamps successfully. The efficiency of the four output piezoelectric transformer is 88.9%, which is higher than the efficiency of single output piezoelectric transformer with a capacitors based current balance circuit ─ 82.3%. But the output power of the single output piezoelectric transformer with a capacitor based current balance circuit is 52.8W, which is larger than 50.4W, the total output power of four output piezoelectric transformers. And the current is more balanced in the single output piezoelectric transformer with a capacitor based current balance circuit, but almost the same with the other. The result in the thesis shows that driving multiple T5 lamps in parallel with piezoelectric transformera and current balance circuits to substitute conventional electromagnetic ballast is possible.