This diploma thesis describes the piezoelectric phenomenon and its use for positioning with nanometric precision in laboratory use. In the thesis is description of direct and indirect piezoelectric phenomenon, various types of piezoelectric actuators and ways of their control with the aim of eliminating their hysteresis. The goal is to design a controller for piezo actuator built in the three-axis nanometric manipulator Thorlabs MAX341/M.

The main subject of this diploma’s thesis is the creation of laboratory task on the partial discharge. The thesis is made up of two parts: theoretical and practical. In the theoretical part there are information about partial discharge. One of them is classification partial discharge by type, effects of partial discharge in insulation systems, parameters to assess the quality of electrical insulation of power systems and measurement techniques. Further part is user’s manual for measurement instrument. In practical part is created laboratory task on problematic of the partial discharge measurement. It is demonstrative measure of partial discharge with the aim of understanding problematic of partial discharge, calibration and noise.

<p>Fruits play a necessary role in the human diet, and their cultivation is important to the prosperity of any country worldwide. However, fruit waste generated in large quantities in agricultural value chain is normally used to feed animals or directly disposed to landfill, ending up with low economic value and a heavy environmental burden. Agricultural waste that contains significant amounts of bioactive compounds can be utilized as byproducts and valorized through bioactives recovery. Conventional bioactive compounds extraction includes intensive uses of organic solvents and also has relatively low efficiency. Therefore, an environment-friendly alternative with higher extraction efficiency is needed. Cold plasma can convert gaseous medium to a highly reacting state with low energy cost, generating reactive species that are able to disrupt cell structures as well as modify material surfaces. This study has developed an innovative cold plasma-assisted extraction technology to enhance the recovery of bioactive compounds from fruit processing byproducts. The objectives of this study are to examine the effects of dielectric barrier discharge plasma on fruit pomaces, in terms of (i) surface microstructure and properties, (ii) extraction efficiency of their bioactive compounds, and (iii) bioactives composition and nutritional value of their extracts.</p><p>High voltage atmospheric cold plasmas (HVACP) generated with different working gases (air, argon, helium and nitrogen) were applied on tomato pomace (TP). In addition to creating ruptures on TP epidermal cells, HVACP treatments were found to decrease the water contact angles of tomato peels and accelerate the drying of tomato fruits, indicating the formation of more hydrophilic surfaces. Helium and nitrogen plasmas-treated TP showed increased PC extraction yields by 10%, and all HVACP-treated samples exhibited higher AA and changes in their phenolic compositions.</p><p>Grape pomace (GP) from red wine production was treated by helium-HVACP for different time periods (5, 10 and 15 min). Similar cell structure disruption and surface hydrophilicity enhancement were observed, and the effects became more significant as treatment extended. HVACP treatment also increased the total phenolic content in GP extracts, by 10.9−22.8%, which contained a higher anthocyanin concentration and showed an improved AA (16.7−34.7%). Furthermore, competitive effects of HVACP treatment on PC extractability enhancement and their degradation were observed.</p><p>The results of this study have proved that HVACP-assisted extraction successfully improved the extraction efficiency of bioactive compounds from fruit pomace and enhanced the nutritional quality of their extracts. This novel technology is a promising method for valorizing different agriculture byproducts into functional food ingredients and nutraceuticals with high nutritional values, which thus can bring significant economic benefits to the agricultural, food and nutraceutical industries.</p>

The conductivity is one of the main properties of HVDC cable insulation materials and needs to be evaluated carefully. Since measurement on cables is time consuming, often thin specimens and normal conductivity measurement cells are used to compare the materials. In this way however, the bulk effects will be less represented in the measurement and the results will be less representative. Instead, one needs to perform the measurements on thick plate samples and with higher voltage levels. This work focuses on the conductivity measurements on thick HVDC insulation plate samples subject to a high electric field and carefully controlled conditions. In the literature, there are many different methods of measuring the leakage current such as dielectric spectroscopy, PD, IV and PEA measurements. In this thesis a three electrode setup is used to measure the leakage current where the electrodes are placed inside the oven.  This is to be able to control both temperature and high voltage under similar and different conditions where it is possible to change these two parameters during measurement. This was made by two Labview programs; one for creating a schedule and one control program which controls the equipment in the cell.  The task was to make sure that the cell functioned by obtaining repeatable and reasonable measurements.  The results that were obtained were reasonable and verified that the cell functioned. The executed measurements were performed in order to achieve a better understanding of error factors in the measurement system, ranging from preparing the sample to measuring the leakage current. The purpose with the cell is it to investigate the quality of the HVDC insulation by conductivity measurements on millimetre thick plate samples. / Den elektriska konduktiviteten är en av de viktigaste egenskaperna av HVDC kablars isolationsmaterial, XLPE, och den måste utvärderas noggrant. Mätning på fullskaliga kablar är tidskrävande och för att jämföra material används istället ofta tunna prover och normerade konduktivitetmätningsceller. En nackdel med denna metod är att bulkeffekterna blir mindre framträdande i mätningen och resultaten kommer att vara mindre representativa. Istället måste man utföra mätningen på tjockare prover och vid högre spänning. Detta examensarbete fokuserar på mätning av ledningsförmåga hos tjocka HVDC- isolationsprover under noggrant kontrollerade förhållanden och starka elektriska fält. I litteraturen finns det många olika metoder att mäta läckströmmar på, till exempel dielektrisk spektroskopi, PD, IV och PEA mätningar för att nämna några. I denna avhandling kommer ett tre-elektrod system att användas där en temperatursensor är monterad på ena elektroden. Systemet används för att både mäta läckströmmar och temperatur vid provet. Detta gör det möjligt att kontrollera temperatur och spänning oberoende av varandra vilket gjordes med hjälp av två Labview program. Det ena för att skapa ett schema och det andra användes som kontrollprogram för att styra utrustningen i cellen. Uppgiften var att kontrollera cellens funktion genom att erhålla rimliga repeterbara mätningar. Mätningarna gav rimliga resultat vilket indikerade att cellen fungerar tillfredställande. Syftet med mätningarna var att få en bättre förståelse för felfaktorer i mätsystemet som kan vara allt från att förbereda provet till att mäta läckström. Syftet med cellen är att undersöka isolationsegenskaperna på millimetertjocka pressade XLPE prover.

There is always a need for more compact designs of power transformers free of partial discharges, in order to save cost on the construction and required material resources. The physical geometric constrictions inside the transformer tank would demand field-grading techniques to homogenise the field strength distribution on oil-solid interfaces, when required. Standard filler materials such as carbon black or silicon carbide (SiC) have a too high electrical conductivity yielding an appropriate grading field strength values for air-related applications. Because insulation oil has a higher electrical breakdown strength, the electrical conductivity must be engineered to lower values in order to reach a higher effective grading field strength. This paper presents the investigation of a new material system based on a phenolic resin Lerg FL-500 and the electrically functionalized ceramic filler particles Merck Iriotec®7550 that enable a resistive electrical field grading in insulation oil. In order to verify the principle functionality of the proposed field grading system, a layer is applied on a substrate surface representing possible oil-solid-interface inside oil-filled power transformers. First, the manuscript describes the methods of specimen preparation and the measurement of the nonlinear current-time behaviour under AC voltage stress for different filler contents. Second, a concurring optical and electrical determination of the partial discharge inception and extinction voltage of a modified Toepler arrangement allows the indirect determination of the electrical field strength distribution along the functionalized layer without the need of direct measurement. To do so, the radius of the circular functional layer is varied and with it the specific grading length. In analogy to state of the art SiC-filled systems, a linear dependency between the effective grading length and the PD inception voltage is observed. The quotient of voltage drop over a varied radius yields the effective graded electric field strength.

La récupération de l'énergie des vibrations est un concept relativement nouveau qui peut être utilisé dans l'alimentation des dispositifs embarqués de puissance à micro-échelle avec l'énergie des vibrations omniprésentes dans l’environnement. Cette thèse contribue à une étude générale des récupérateurs de l'énergie des vibrations (REV) employant des transducteurs électrostatiques. Un REV électrostatique typique se compose d'un transducteur capacitif, de l'électronique de conditionnement et d’un élément de stockage. Ce travail se concentre sur l'examen du circuit de conditionnement auto-synchrone proposé en 2006 par le MIT, qui combine la pompe de charge à base de diodes et le convertisseur DC-DC inductif de type de flyback qui est entraîné par le commutateur. Cette architecture est très prometteuse car elle élimine la commande de grille précise des transistors utilisés dans les architectures synchrones, tandis qu'un commutateur unique se met en marche rarement. Cette thèse propose une analyse théorique du circuit de conditionnement. Nous avons développé un algorithme qui par commutation appropriée de flyback implémente la stratégie de conversion d'énergie optimale en tenant compte des pertes liées à la commutation. En ajoutant une fonction de calibration, le système devient adaptatif pour les fluctuations de l'environnement. Cette étude a été validée par la modélisation comportementale.Une autre contribution consiste en la réalisation de l'algorithme proposé au niveau du circuit CMOS. Les difficultés majeures de conception étaient liées à l'exigence de haute tension et à la priorité de la conception faible puissance. Nous avons conçu un contrôleur du commutateur haute tension de faible puissance en utilisant la technologie AMS035HV. Sa consommation varie entre quelques centaines de nanowatts et quelques microwatts, en fonction de nombreux facteurs - paramètres de vibrations externes, niveaux de tension de la pompe de charge, la fréquence de la commutation de commutateur, la fréquence de la fonction de calibration, etc.Nous avons également réalisé en silicium, fabriqué et testé un commutateur à haute tension avec une nouvelle architecture de l'élévateur de tension de faible puissance. En montant sur des composants discrets de la pompe de charge et du circuit de retour et en utilisant l'interrupteur conçu, nous avons caractérisé le fonctionnement large bande haute-tension du prototype de transducteur MEMS fabriqué à côté de cette thèse à l'ESIEE Paris. Lorsque le capteur est excité par des vibrations stochastiques ayant un niveau d'accélération de 0,8 g rms distribué dans la bande 110-170 Hz, jusqu'à 0,75 µW de la puissance nette a été récupérée. / Vibration energy harvesting is a relatively new concept that can be used in powering micro-scale power embedded devices with the energy of vibrations omnipresent in the surrounding. This thesis contributes to a general study of vibration energy harvesters (VEHs) employing electrostatic transducers. A typical electrostatic VEH consists of a capacitive transducer, conditioning electronics and a storage element. This work is focused on investigations of the reported by MIT in 2006 auto-synchronous conditioning circuit, which combines the diode-based charge pump and the inductive flyback energy return driven by the switch. This architecture is very promising since it eliminates precise gate control of transistors employed in synchronous architectures, while a unique switch turns on rarely. This thesis addresses the theoretical analysis of the conditioning circuit. We developed an algorithm that by proper switching of the flyback allows the optimal energy conversion strategy taking into account the losses associated with the switching. By adding the calibration function, the system became adaptive to the fluctuations in the environment. This study was validated by the behavioral modeling. Another contribution consists in realization of the proposed algorithm on the circuit level. The major design difficulties were related to the high-voltage requirement and the low-power design priority. We designed a high-voltage analog controller of the switch using AMS035HV technology. Its power consumption varies between several hundred nanowatts and a few microwatts, depending on numerous factors - parameters of external vibrations, voltage levels of the charge pump, frequency of the flyback switching, frequency of calibration function, etc. We also implemented on silicon, fabricated and tested a high-voltage switch with a novel low power level-shifting driver. By mounting on discrete components the charge pump and flyback circuit and employing the proposed switch, we characterized the wideband high-voltage operation of the MEMS transducer prototype fabricated alongside this thesis in ESIEE Paris. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110-170 Hz, up to 0.75 $\mu$W of net electrical power has been harvested.

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Today, Alstom has several types of High-Voltage sections (HV), which are adapted for every new type of train. Some are very similar in size and components and others are more different. The purpose of this master's thesis was to come up with a way to split this HV box into smaller modules and assemble them using frame- and fastener concepts to simplify the manufacturing and assembly of the HV section. The work consisted of concept generation in parallel or both the frames and fasteners, then evaluating them through matrices using different priorities and parameters. The detail-construction used supported simulations and discussions with Alstom to come up with the final product while incorporating the existing demands of lifespan, durability, and IP-rating. The result was two different fastening concepts between modules which were named “Twist Lock” and “Corner Cut”. They are both using a frame design that utilized adaptable plates that differentiated depending on the intended purpose of the module and its placement in the configuration. The majority of the frame is standardized for all modules while smaller gland plates with different electrical connections are placed depending on the internal components. The fasteners were chosen for ease of assembly according to set strength requirements. “Corner Cut” uses the corners on the exterior of the frame to assemble using bolts and nuts. The “Twist Lock” concept is fastened through the interior and the frame was adjusted so that assembly does not interfere with the internal components. If one of the concept is chosen to be used, Alstom will be able to offer eight different configurations, instead of the two configurations that they have today. To proceed, the attachment must be tested practically based on the set strength requirements. / Idag har Alstom flera typer av högspännings-sektioner (HV) som är anpassade för varje ny tågtyp. Vissa av dem är mycket lika i storlek och komponenter och andra skiljer sig mer åt. Syftet med detta examensarbete var att hitta ett sätt att dela upp denna HV-låda i mindre moduler och montera dem med hjälp av ram- och infästningskoncept för att förenkla tillverkningen och monteringen av HV-sektionen. Arbetet bestod av konceptgenerering parallellt för både ramarna och infästningen, sedan utvärdera dessa genom matriser med olika prioriteringar och parametrar. Detaljkonstruktionen använde stödjande simuleringar och diskussioner med Alstom för att komma fram till den slutliga produkten samtidigt som de befintliga kraven på livslängd, hållbarhet och IP-klassning integrerades. Arbetet resulterade i två olika infästningskoncept mellan modulerna som namngavs “Twist Lock” och “Corner Cut”. De använder båda en ramdesign som utnyttjar anpassningsbara plattor som skiljer sig beroende på modulens syfte och placering i tänkt konfiguration. Majoriteten av ramen är standardiserad för alla moduler medan mindre skruvplattor med elektriska anslutningar placeras beroende på de interna komponenterna. Fästena valdes för att vara enkla att montera utefter satta hållfasthetskrav. ”Corner Cut” använder hörnen på utsidan av ramen och modulerna monteras med hjälp av bultar och muttrar. ”Twist Lock” fästs i stället på insidan och ramen justeras så att montaget inte stör de interna komponenterna. Väljer man att gå över till ett av infästningskoncepten så kan man erbjuda åtta konfigurationer av systemet, i stället för dagens två konfigurationer. För att gå vidare så måste infästningarna testas i produktion utifrån de satta hållfasthetskraven.

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