Made available in DSpace on 2016-08-17T14:52:41Z (GMT). No. of bitstreams: 1 Dissertacao-GuilhermeCarvalhoFarias.pdf: 1837201 bytes, checksum: 75a44efdfd7752087fd597668e388184 (MD5) Previous issue date: 2016-02-29 / This study consists in a comparative analysis of MPPT strategies for low power wind turbines and the development of a control methodology for a battery charging system. The main MPPT strategies in the literature are described and implemented, along with all of their auxiliary control loops. To perform the comparison, a simulation platform is developed. Mathematical modeling of all components in the platform is described, as well as how they relate with each other. This platform allows keeping the system parameters the same for all methods, and modifying only the necessary to implement each of them. The control method for battery charging is presented and analyzed. One of the MPPT strategies described is applied together with this methodology. The methodology of the simulations are performed with switched models to validate the project realized with the developed average models. / Este trabalho consiste na análise comparativa entre métodos MPPT para turbinas eólicas de pequeno porte e desenvolvimento de uma metodologia de controle para um sistema de carregamento de baterias. Os principais métodos de MPPT presentes na literatura são descritos e implementados, juntamente com suas malhas de controle auxiliares. Para realizar a comparação, uma plataforma de simulação é desenvolvida. O modelamento matemático de todos os componentes presentes na plataforma é descrito, bem como a forma como eles se relacionam. Essa plataforma permite manter os parâmetros do sistema iguais para todos os métodos, somente modificando o necessário para implementar cada um deles. A metodologia de controle para carregamento de baterias é apresentada e analisada. Um dos métodos de MPPT descritos é aplicado juntamente à essa metodologia. As simulações da metodologia são realizadas com modelos chaveados, para validar o projeto realizado com os modelos médios levantados.

The objective of this master's thesis is new power converter design for bicycle with combustion engine and electric power transmission. The power converter is control by microprocessor and control algorithm is designed to achieve maximum efficiently of combustion engine. Converter and servomotor for controlling combustion engine throttle are located in metal box. Hardware, firmware and metal box are designed in the thesis.

Object my master’s thesis is the design a Medical device uninterruptible power supply with managment system utilizing I2C bus. Norm EN 61000-3-2 define electric parameters for medical device power supply. In case of power supply for medial equipment is expressive accent on increased electric strength. This power supply have usually primary and secondary power circuit. Primary power circuit form line accumulator, which supplies needed output to the load and recharge reserve battery. Secondary is formed battery-pack, which serve as back-up power supply at drop-out prime circle. They have a minimum weight, small proportions, large overall effectivity also charging battery-pack and monitoring battery-pack charging condition. Result whole those master’s thesis is design Medical device uninterruptible power supply with managment system utilizing I2C bus and realization board layout. Resulting characteristics designed supply unit are: Output voltages are 5V/ 3 A , 12V/ 1,5 A and -12V/ 0,1 A. Managment support information about: Line adapter/ battery pack switch, battery-pack charging condition and actuall tempera-ture battery-pack.

The master‘s thesis deals with DC/DC converters for power LED diodes. Gives an overview of the field of LED lighting technology, analyzes various types of converters and shows their principle of operation. Furthermore presents some possible circuit designs for three different voltage levels and the calculations for each part. As an approval of their functionality the results of their measurements are plotted followed by the data evaluation.

The perceived battery capacity of battery-powered devices can be increased by harvesting energy from readily available sources. Third generation solar cells are a good candidate for this purpose since they can be integrated with these battery-powered devices and harvest power from diffused light. For a single third generation solar cell to be useful in the context of charging a Lithium based battery, the voltage must be increased tenfold. To increase this perceived battery capacity as much as possible, efficiency is crucial. In this thesis, DCDC converter topologies and designs are studied from a system design perspective. The specifications of a converter suitable for interfacing Dye-Sensitised Solar Cells with Lithium batteries are described and a market research is conducted based on those specifications. A comparison of the available commercial solutions is presented, highlighting the most suitable options. However, none of the commercial solutions met the specifications to the full extent. The design process of two DC-DC converters is presented, one is a Boost converter operating in Continuous Conduction Mode and the other is a Boost converter operating in Discontinuous Conduction Mode. A comparison of the two designs highlights the advantages of operating the Boost converter in Discontinuous Conduction Mode when interfaced with a Dye-Sensitised Solar Cell. The design with a Boost converter operating in Discontinuous Conduction Mode has an efficiency of 80.3 % and is capable of tracking the Maximum Power Point of the Dye-Sensitised Solar Cell. / Den uppfattade batterikapaciteten hos batteridrivna enheter kan ökas genom att skörda energi från lättillgängliga källor. Tredje generationens solceller är en bra kandidat för detta ändamål eftersom de kan integreras med dessa batteridrivna enheter och skörda ström från spritt ljus. För att en enda tredje generationens solcell ska vara användbar i samband med laddning av ett litiumbaserat batteri måste spänningen ökas tiofaldigt. För att öka denna uppfattade batterikapacitet så mycket som möjligt är effektiviteten avgörande. I denna avhandling studeras topologier och strategier för DC-DC-omvandlare från ett systemdesignperspektiv. Specifikationerna för en omvandlare som är lämplig för att ansluta Dye-sensitized solceller med litiumbatterier beskrivs och en marknadsundersökning utförs utifrån dessa specifikationer. En jämförelse av de tillgängliga kommersiella lösningarna presenteras och belyser de lämpligaste alternativen. Ingen av de kommersiella lösningarna uppfyllde emellertid specifikationerna i sin helhet. Designprocessen för två DC-DComvandlare presenteras, en Boost-omvandlare som arbetar i kontinuerligt ledande läge och en Boost-omvandlare som arbetar i diskontinuerligt ledande läge. En jämförelse av de två designerna belyser fördelarna med att driva Boost-omvandlaren i diskontinuerligt ledningsläge när den kopplats till en färgkänslig solcell. Konstruktionen med en Boostomvandlare som arbetar i diskontinuerlig ledningsläge har en effektivitet på 80.3 % och kan spåra den maximala effektpunkten för solcellen.

With the development of electric vehicle (EV) charging systems, energy storage systems (ESS), data center power supplies, and solid-state transformer (SST) systems, the fixed-ratio isolated DC-DC converter, namely the DC transformer (DCX), has gained significant popularity. Similar to the passive AC transformer, DCX can bidirectionally convey DC power with very high efficiency. Due to zero-voltage switching (ZVS) and a small root mean square (RMS) current, the open-loop CLLC resonant converter operating at the resonant frequency is a promising candidate for DCX with a constant voltage transfer ratio. In Chapter 2, to solve unsmooth bidirectional power flow and current distortion in the traditional CLLC-DCX with synchronization rectification (SR) modulation, a dual-active-synchronization (DAS) modulation is adopted with identical driving signals on both sides. First, the switching transition of this modulation is thoroughly analyzed considering the large switch's output capacitances. After comparing different transitions, a so-called sync-ZVS transition is more desirable with ZVS, has no deadtime conduction loss, and almost has load-independent voltage gain. An axis and center symmetric (ACS) method is proposed to achieve this switching transition. Based on this method, an overall design procedure of CLLC-DCX with DAS modulation is also proposed. However, designing a high-power and high-frequency transformer for CLLC-DCX presents significant challenges due to the trade-off between thermal management, leakage inductance minimization, and insulation requirements. To overcome this trade-off between power rating and operation frequency, a scalable electronic-embedded transformer (EET) with a low-voltage bridge integrated into the transformer windings is proposed in Chapter 3. The EET addresses the challenge through simple open-loop control and natural current sharing, enabling easy parallel connection and scaling to different power ratings. Based on this concept, a bidirectional, EET-based DC transformer (EET-DCX) is proposed to solve the transformer-level paralleling and resonant point shift issues in traditional LLC-DCX designs. By employing the embedded full bridge, the EET-DCX effectively cancels out the impedance of the leakage inductance, ensuring optimal operation at any frequency. Additionally, the EET-DCX retains the inherent advantages of the LLC-DCX, such as load-independent voltage gain, simple open-loop control, full-load range ZVS, and low circulating current. Leveraging these advantages, the proposed EET-DCX solution has the potential to push the boundaries of transformer performance to the MHz operation frequency range with hundreds of kilowatts of power capability. Moreover, to address the significant RMS current problem of the CLLC-DCX, a trapezoidal current modulation is also proposed in Chapter 3. Compared to the CLLC-DCX with a sinusoidal current, an EET-DCX with a trapezoidal current can reduce the total conduction loss by up to 23%. This total conduction loss includes semiconductor loss on both high-voltage and low-voltage bridges and transformer winding loss. In light of this EET concept, another resonant commutation (RC) EET-DCX is proposed to streamline the circuit. First, it replaces the embedded full bridge with a low-voltage bidirectional AC switch. Second, it introduces a resonant current commutation to realize a quasi-trapezoidal transformer current with a smaller RMS value. Compared to the triangular current produced by the original EET-DCX, the RMS current can be decreased by 15%. By incorporating only one embedded bidirectional AC switch, the high-frequency transformer leakage inductance impedance is fully neutralized. As a result, the rated power of the proposed RC EET-DCX can be readily scaled up through transformer-level parallelism. Furthermore, the RC EET-DCX maintains the benefits of a typical LLC/CLLC-DCX, including load-independent voltage gain, full load range ZVS, and low circulating current. However, either in EET-DCX or RC EET-DCX, the trapezoidal current modulation will increase the voltage stress on the low-voltage full bridge or bidirectional AC switch, especially when the leakage inductance is large and variable, such as in the high-power wireless charging application. To address this trade-off between RMS current and voltage stress, this paper proposes the concept of a hybrid resonant-type EET-DCX with a series resonant capacitor. Following this concept, two specific topologies, hybrid EET-DCX and hybrid RC EET-DCX, are proposed. The main difference between these topologies is that the former adopts a full bridge. In a hybrid RC EET-DCX, a resonant current commutation scheme is developed. Among these topologies, since the passive capacitor can mainly cancel the leakage inductance impedance, the full bridge or AC switch only needs to handle the remaining impedance. Thus, the voltage stress on active components can be dramatically decreased. Additionally, these two proposed topologies can retain all the advantages of previous EET-DCX designs, including natural current sharing, load-independent voltage gain, simple open-loop control, and full-load range ZVS. The comparison between these two topologies is thoroughly studied. Finally, a 12-kW DCX testbench is built to verify all the analysis and performance in Chapter 3. If output voltage regulation is required, DCX can cooperate with other voltage regulators to realize high conversion efficiency and power density. In Chapter 4, two DCX applications are implemented: an 18-kW 98.8% peak efficiency EV battery charger with partial power processing and a 50-kW symmetric 3-level buck-boost converter with common-mode (CM) noise reduction. In the first battery charger, a large portion of the power is handled by an 18 kW CLLC-DCX, and the remaining partial power goes through a 3-phase interleaved buck converter. The proposed switching transition optimization in Chapter 2 is adopted in the 18-kW CLLC-DCX to realize 98.8% peak efficiency. To handle the step-up and step-down cases at the same time, a symmetric 3-level buck-boost converter with coupled inductors is also studied as a post regulator. With symmetric topology and quadrangle current control, the converter can achieve a CM noise reduction and full load range ZVS with a small RMS current. To further optimize the performance and simplify the control, a mid-point bridging with a better CM noise reduction and a split capacitor voltage auto-balance is implemented. A 50-kW prototype is built to verify the above analysis. To summarize, Chapter 2 first proposes a switching transition optimization for CLLC-DCX. Later, to address the intrinsic trade-off between transformer rating power and frequency, an EET concept and its corresponding soft-switching DCX family are found in Chapter 3. Finally, to handle voltage regulation, two examples for practical applications are studied in Chapter 4 —one is an 18-kW partial power converter, and the other is a 50-kW 3-L buck-boost converter. Finally, Chapter 5 will draw conclusions and illustrate future work. / Doctor of Philosophy / With the development of electric vehicle (EV) charging systems, energy storage systems (ESS), data center power supply, and solid-state transformer (SST) systems, the fixed-ratio isolated dc-dc converter, namely dc transformer (DCX), has gained significant popularity. However, designing a high-performance DCX still has many challenges, such as large dead time loss, poor current sharing, and sensitivity to parameter tolerance. Firstly, the state-of-the-art resonant CLLC-DCX is optimized in Chapter 2. With an optimal switching frequency and dead time, both the primary and secondary sides of zero voltage switching (ZVS) can begin and finish simultaneously, which means dead time loss caused by current through the body diode can be eliminated. Therefore, the efficiency of CLLC-DCX can be improved. However, designing a high-power and high-frequency CLLC-DCX transformer still presents significant challenges due to the trade-off between thermal management, leakage inductance minimization, and insulation requirements. To overcome this trade-off, in Chapter 3, a scalable electronic-embedded transformer (EET) concept with a low-voltage bridge integrated into the transformer windings is proposed. The EET addresses the challenge through its simple open-loop control and natural current sharing, enabling easy parallel connection and scaling to different power ratings. In light of this EET concept, a new family of soft-switching DCXs is proposed for different applications, such as high-power wireless charging systems. All these EET-based DCXs retain the merits of typical CLLC-DCX, such as small circulating current ringing, small turn-off current, full load range ZVS, and load-independent gain. After realizing a desirable design for DCX, Chapter 4 presents two DCX applications with voltage regulation. Firstly, an 18 kW 98.8% peak efficiency battery charger is designed with partial power processing. Most of the power will go through an optimized DCX, and the remaining small portion of power will go through a 3-phase interleaved buck converter. On the other hand, DCX can also be adopted as a front-end or rear-end converter in a typical two-state DC-DC converter. As for another stage, a non-isolated DC-DC converter with a large output range can be used to handle voltage regulation. Following this structure, a 50-kW symmetric 3-L buck-boost converter with coupled inductors and reduced common emission is proposed. To summarize, the state-of-the-art CLLC-DCX is optimized in Chapter 2. Afterward, a new concept of EET-DCX and its corresponding DCX family is proposed in Chapter 3. After obtaining an optimized DCX, two practical applications with DCX are implemented in Chapter 4. Finally, Chapter 5 will draw conclusions and illustrate future work.

KTH is funding a project whose goal is to send a satellite into space. This project is called MIST (Miniature Student Satellite) which is assembled by a team of students at KTH. On the satellite there are experiments that are invented by other teams, in two of those experiments a power supply is required. This thesis is a technical investigation on how to design the power supply to both of those experiments, which are called SiC and Piezo LEGS. Piezo LEGS will investigate how their nanosized motors will behave and function in a space environment. SiC will investigate how their silicone carbide transistors will be affected by the space environment. A team made of four other students was selected to produce SiC experiments and a PCB in which this work is included. A literature study was done to get a better understanding of how power supplies work and to know how to select a good power supply. When the power supplies were selected they were simulated to meet the requirements. The next step was to do a Printed Circuit Board(PCB) for the SiC experiment and Piezo LEGS to be able to test the power supplies functionality in the physical world. Both of the converters reached the required output and characteristics working on their respective PCB. More time is needed for long time testing and optimization on the PCB layouts. / MIST (Miniature Student Satellite) är ett av KTH subventionerat projekt vilket har som mål att skicka upp en satellit i rymden. Projektet kommer omfatta flera olika experiment. Piezo LEGS ska undersöka en motors funktionalitet i rymdmiljö. SiC ska undersöka hur Silicon carbide halvledare och transistorer påverkas av rymdmiljön. Båda experimenten kräver varsin strömförsörjning för att fungera. Detta projekt ska undersöka kraven på strömförsörjning samt testa prototypen av ett kretskort för densamma. Först genomfördes en förstudie av de två typer av regulatorer som vanligtvis används som strömförsörjning, den linjära regulatorn och switch-mode regulatorn för att förklara olika strömförsörjningsteknologier, samt ta reda på de olika miljökraven. Baserat på förstudiens resultat erhölls kunskap för hur tester ska tas fram för funktionalitet av regulatorerna så att de når kraven för MIST för att sedan kunna producera de båda regulatorerna. Målet är att resultatet av simuleringarna på strömförsörjningen ska stämma överens med utfallet av kretskorten som produceras. Mätningar genomfördes på prototyp kretskort som visade att simuleringarna var korrekta och gav strömförsörjningen rätt resultat på kretskorten. Några av funktionerna på regulatorerna hann ej testas på grund av tidsbrist och mycket framtida arbete kvarstår.

Electrical energy is used at approximately the rate of 15 Terawatts world-wide. Generating this much energy has become a primary concern for all nations. There are many ways of generating energy among which the most commonly used are non-renewable and will extinct much sooner than expected. Very active research is going on both to increase the use of renewable energy sources and to use the available energy with more efficiency. Among these sources, solar energy is being considered as the most abundant and has received high attention. The mobile phone has become one of the basic needs of modern life, with almost every human being having one.Individually a mobile phone consumes little power but collectively this becomes very large. This consideration motivated the research undertaken in this masters thesis. The objective of this thesis is to design a model for solar power based charging circuits for mobile phone using Simulink(R). This thesis explains a design procedure of solar power based mobile charger circuit using Simulink(R) which includes the models for the photo-voltaic array, maximum power point tracker, pulse width modulator, DC-DC converter and a battery. The first part of the thesis concentrates on electron level behavior of a solar cell, its structure and its electrical model.The second part is to design an array of solar cells to generate the desired output. Finally, the third part is to design a DC-DC converter which can stabilize and provide the required input to the battery with the help of the maximum power point tracker and pulse width modulation. The obtained DC-DC converter is adjustable to meet the requirements of the battery. This design is aimed at charging a lithium ion battery with nominal voltage of 3.7 V, which can be taken as baseline to charge different types of batteries with different nominal voltages.

Energy harvesting is identified as an alternative solution for powering implantable biosensors. It can potentially enable the development of self-powered implants if the harvested energy is properly handled. This development implies that batteries, which impose many limitations, are replaced by miniature harvesting devices. Customized interface circuits are necessary to correct for differences in the voltage and power levels provided by harvesting devices from one side, and required by biosensor circuits from another. This thesis investigates the available harvesting sources within the human body, proposes various methods and techniques for designing power-efficient interfaces, and presents two CMOS implementations of such interfaces. Based on the investigation of suitable sources, this thesis focuses on glucose biofuel cells and thermoelectric harvesters, which provide appropriate performance in terms of power density and lifetime. In order to maximize the efficiency of the power transfer, this thesis undertakes the following steps. First, it performs a detailed analysis of all potential losses within the converter. Second, in relation to the performed analysis, it proposes a design methodology that aims to minimize the sum of losses and the power consumption of the control circuit. Finally, it presents multiple design techniques to further improve the overall efficiency. The combination of the proposed methods and techniques are validated by two highly efficient energy harvesting interfaces. The first implementation, a thermoelectric energy harvesting interface, is based on a single-inductor dual-output boost converter. The measurement results show that it achieves a peak efficiency of 86.6% at 30 μW. The second implementation combines the energy from two sources, glucose biofuel cell and thermoelectric harvester, to accomplish reliable multi-source harvesting. The measurements show that it achieves a peak efficiency of 89.5% when the combined input power is 66 μW. / Energiskörd har identifierats som en alternativ lösning för att driva inplanterbara biosensorer. Det kan potentiellt möjliggöra utveckling av själv-drivna inplanterbara biosensorer. Denna utveckling innebär att batterier, som sätter många begränsningar, ersätts av miniatyriserade energiskördsenheter. Anpassade gränssnittskretsar är nödvändiga för att korrigera för de skillnader i spänning och effektnivå som produceras av de energialstrande enheterna, och de som krävs av biosensorkretsarna. Denna avhandling undersöker de tillgängliga källorna för energiskörd i den mänskliga kroppen, föreslår olika metoder och tekniker för att utforma effektsnåla gränssnitt och presenterar två CMOS-implementeringar av sådana gränssnitt. Baserat på undersökningen av lämpliga energiskördskällor, fokuserar denna avhandling på glukosbiobränsleceller och termoelektriska energiskördare, som har lämpliga prestanda i termer av effektdensitet och livstid. För att maximera effektiviteten hos effektöverföringen innehåller denna avhandling följande steg. Först görs en detaljerad analys av alla potentiella förluster inom boost-omvandlare. Sedan föreslår denna avhandling en designmetodik som syftar till att maximera den totala effektiviteten och effektförbrukningen. Slutligen presenterar den flera designtekniker för att ytterligare förbättra den totala effektiviteten. Kombinationen av de föreslagna metoderna och teknikerna är varierade genom två högeffektiva lågeffekts energigränssnittskretsar. Den första inplementeringen är ett termoelektriskt energiskördsgränssnitt baserat på en induktor, med dubbla utgångsomvandlare. Mätresultaten visar att omvandlaren uppnår en maximal effektivitet av 86.6% vid 30 μW. Det andra genomförandet kombinerar energin från två källor, en glukosbiobränslecell och en termoskördare, för att åstadkomma en tillförlitlig multi-källas energiskördslösning. Mätresultaten visar att omvandlaren uppnår en maximal effektivitet av 89.5% när den kombinerade ineffekten är 66 μW. / <p>QC 20170508</p> / Mi-SoC

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη και τη μοντελοποίηση ενός αιολικού συστήματος παραγωγής ηλεκτρικής ενέργειας βασισμένο σε σύγχρονη γεννήτρια μόνιμου μαγνήτη (PMSG). Ειδικότερα, παρουσιάζονται και αναλύονται όλα τα τμήματα που αποτελούν το αιολικό σύστημα καθώς και οι λογικές ελέγχου που ακολουθήθηκαν για την αποτελεσματική λειτουργία του. Επιπλέον, μελετάται και μοντελοποιείται μια διάταξη αποθήκευσης ενέργειας από την οποία πλαισιώνεται το αιολικό σύστημα κατά την αυτόνομη λειτουργία του. Τέλος, παρουσιάζονται και σχολιάζονται τα αποτελέσματα της προσομοίωσης της λειτουργίας του συστήματος, σε σύνδεση με το δίκτυο και κατά την αυτόνομη λειτουργία του. Για την ανάπτυξη του μοντέλου και την προσομοίωση χρησιμοποιήθηκε το πρόγραμμα Simulink/Matlab. Στο Κεφάλαιο 1 γίνεται αναφορά στο ενεργειακό πρόβλημα και μια γενική εισαγωγή στις ανανεώσιμες πηγές ενέργειας. Επιπλέον, δίνονται διάφορες πληροφορίες γύρω από την αιολική ενέργεια και αναλύονται τα πλεονεκτήματα και μειονεκτήματα της χρήσης ανεμογεννητριών. Επίσης, παρουσιάζεται η δομή μιας ανεμογεννήτριας και παραθέτονται διάφοροι τύποι ανεμογεννητριών, ενώ δίνονται και οι βασικές σχέσεις μετατροπής της αιολικής ενέργειας σε ηλεκτρική. Στο Κεφάλαιο 2 γίνεται ανάλυση κάθε τμήματος της ανεμογεννήτριας (πτερωτή, σύστημα μετάδοσης κίνησης, γεννήτρια) και παρατίθενται οι εξισώσεις που περιγράφουν τη λειτουργία τους. Επιπρόσθετα, παρουσιάζεται ο τρόπος μοντελοποίησης του κάθε τμήματος στο περιβάλλον του Simulink. Ιδιαίτερη έμφαση δόθηκε στη μελέτη της σύγχρονης γεννήτριας μόνιμου μαγνήτη καθώς παρουσιάζεται με λεπτομέρεια η δομή της καθώς και οι αρχές που διέπουν τη λειτουργία της. Τέλος, δίνονται όλα τα χαρακτηριστικά μεγέθη της ανεμογεννήτρια που χρησιμοποιήθηκε στην παρούσα εργασία. Στο Κεφάλαιο 3 αρχικά, γίνεται μια γενική παρουσίαση των στοιχείων που αποτελούν τους μετατροπείς, ενώ στη συνέχεια παρουσιάζονται οι βασικές κατηγορίες μετατροπέων που υπάρχουν και αναφέρονται μερικοί βασικοί τύποι μετατροπέων που βρίσκουν εφαρμογή σε αιολικά συστήματα γενικότερα. Έπειτα, το κεφάλαιο επικεντρώνεται στους μετατροπείς που χρησιμοποιήθηκαν στο αιολικό σύστημα της παρούσας εργασίας καθώς εξηγείται ο τρόπος λειτουργίας τους και παρουσιάζεται ο τρόπος μοντελοποίησης τους στο Simulink. Έμφαση δόθηκε στον dc/dc μετατροπέα ανύψωσης τάσης που χρησιμοποιήθηκε, όπου γίνεται διαστασιολόγηση και παρουσιάζεται μια μικρή προσομοίωση της λειτουργίας του. Τέλος, παρουσιάζεται, επίσης, το φίλτρο που τοποθετείται στην έξοδο του αντιστροφέα. Στο Κεφάλαιο 4 περιγράφονται αναλυτικά η τεχνική διαμόρφωσης εύρους παλμών (PWM) και η τεχνική της ημιτονοειδούς διαμόρφωσης εύρους παλμών (SPWM), οι οποίες και εφαρμόστηκαν για την παλμοδότηση των μετατροπέων. Στη συνέχεια, περιγράφονται αναλυτικά οι μηχανισμοί ελέγχου που εφαρμόστηκαν με τη βοήθεια PI ελεγκτών, τόσο στην πλευρά της μηχανής (dc/dc μετατροπέας ανύψωσης τάσης) όσο και στον αντιστροφέα του αιολικού συστήματος. Στο Κεφάλαιο 5 παρουσιάζονται και σχολιάζονται τα αποτελέσματα της προσομοίωσης του αιολικού συστήματος σε σύνδεση με το δίκτυο. Το σύστημα προσομοιώνεται για δύο περιπτώσεις, σε πρώτη φάση γίνεται προσομοίωση του συστήματος υπό σταθερή ταχύτητα ανέμου ίση με 12 m/s και σε δεύτερη φάση προσομοιώνεται η λειτουργία του συστήματος για βηματικές μεταβολές της ταχύτητας του ανέμου. Στο Κεφάλαιο 6 μελετάται η αυτόνομη λειτουργία του αιολικού συστήματος το οποίο, πλέον, πλαισιώνεται με μια διάταξη αποθήκευσης ενέργειας. Αρχικά, παρουσιάζεται το σύστημα αποθήκευσης ενέργειας που χρησιμοποιήθηκε. Συγκεκριμένα η συστοιχία μπαταριών της οποίας δίνονται τα χαρακτηριστικά μεγέθη, καθώς και το μοντέλο της στο Simulink. Επίσης, παρουσιάζεται και μοντελοποιείται ο dc/dc μετατροπέας δύο κατευθύνσεων ο οποίος συνδέει τη συστοιχία με το υπόλοιπο σύστημα. Στη συνέχεια, περιγράφεται αναλυτικά ο μηχανισμός ελέγχου που εφαρμόζεται στη διάταξη αποθήκευσης ενέργειας για τον έλεγχο της φόρτισης/εκφόρτισης. Στο τέλος του κεφαλαίου παρουσιάζονται τα αποτελέσματα της προσομοίωσης του αυτόνομου αιολικού συστήματος για σταθερή ταχύτητα ανέμου-μεταβαλλόμενο φορτίο και για μεταβαλλόμενο άνεμο-σταθερό φορτίο. / In this thesis, a wind energy conversion system (WECS) based on a permanent magnet synchronous generator (PMSG) was studied and simulated. All parts of the WECS are presented and discussed in detail. Furthermore, control strategies for the generator-side converter and the voltage source inverter are developed. The WECS is simulated both in grid connected and stand-alone mode. In the stand-alone mode, the WECS is supplied with an energy storage system for which a bi-directional buck/boost converter and control strategy was designed. Finally, simulation results are presented and performance of the system in various modes of operation is evaluated. Simulink/Matlab is used for modeling and simulating the WECS. At the beginning of Chapter 1, a discussion of energy crisis and renewable energy sources is held. Furthermore, information about wind energy has been reviewed and its benefits and drawbacks are examined. In addition, the structure of a wind turbine and the principles of converting wind energy into electricity are presented. In Chapter 2 all parts of the wind turbine are studied and its characteristics are specified. Even more, the model of every part in Simulink is presented. Theoretical background, structure and operation principles of PMSG are presented in detail. In Chapter 3, firstly a general presentation of converters components takes place. Then the major existing categories of converter are presented and some basic types of converters, which are generally used in WECS, are mentioned. Moreover, the chapter focuses on the converters that are used in this thesis, explaining the way they operate. After all, their models in Simulink are shown. Emphasis was given to the dc/dc boost converter whose parameters are calculated and its operation is simulated. Finally, there is a presentation of the filter which was placed at the output of the inverter. In Chapter 4, Pulse-width Modulation (PWM) and Sinusoidal Pulse-width Modulation (SPWM) techniques that are used in this thesis are described. Moreover, the control strategy for the generator-side converter with maximum power extraction is presented. The control strategy of the voltage sourced inverter is shown as well. In Chapter 5 simulation results of the grid connected WECS are presented and evaluated. On the first part of the presentation, the WECS is simulated for constant wind speed (12m/s), and in the second part for step-changed wind speed. In Chapter 6 the stand-alone operation of the WECS is studied and supplied with an energy storage system. Initially, there is an analysis of the energy storage system, which was used, and in particular the battery bank, whose characteristics are given. Moreover, a Bi-directional dc/dc Buck-Boost converter which is used to interconnect the battery bank to the dc-link is presented and modeled. Afterwards, there is a detailed description of the control strategy used in order to control charging / discharging of the battery bank. At the end of this chapter, simulation results of two different stand-alone operation modes are presented, one with constant wind speed and variable load and the other one with step-changing wind speed and constant load.