This thesis deals with the asynchronous engines, describes their structure, principles, properties, use, and briefly describes the design of three-phase asynchronous motor. The first section describes the most common three-phase induction motor, the emergence of the rotating magnetic field and the basic relationships. The second part deals with asynchronous motors for specific applications, their design and features. The next section is an analysis engine borrowed from the electric company ATAS Náchod, and The last section lists ways to improve the basic parameters of induction motors designed and optimized engine.

Electric drives used in automotive industry are often based on standard DC motor as it is widely recognised as mature and reliable technology. The most common applications of DC motors in automotive industry are starters and wind screen wiper motors. Aim of this thesis is to provide design overview of typical automotive DC motor therefore main parts and features of the machine will be described in detail. Main disadvantage of DC motor is „sliding contact“ between commutator and carbon brushes which introduces source of electromagnetic disturbance and requires regular maintenance. Within this project different aspects of DC motor design and innovation are expected to be tackled including examples of loss calculation.

Diploma Thespis is focused on development, parameters and construction of one-phase induction motor underplayed by calculations. Emphasis was dealt to simplify motor development process by developed computer program. Program calculations were approved by parallel by hand calculations and by experimental measuring of real processed motor.

In this thesis is described the function and design of the transformer designed on ferromagnetic core, composed of transformer sheets. It is explained a transient inrush current of the transformer. In this work is inserted voltage and current waveforms, designed printed circuit board, serving to reduce the inrush current.

In this thesis is described the function and design of the transformer designed on ferromagnetic core, composed of transformer sheets. It is explained a transient inrush current of the transformer. In this work is inserted voltage and current waveforms, designed printed circuit board, serving to reduce the inrush current.

The master's thesis deals and introduces a single-phase inductions machines, the principle of operation, types of design and operating conditions. This thesis includes analysis of individual losses in the machine and reduce the possibility of different ways. After a theoretical proposal for reducing losses are measured by mass-produced single-phase induction machine. Further machine modifications proposed for reducing losses in the stator windings and designed a prototype machine with the adjustment of the magnetic circuit to reduce iron losses made by ATAS elektromotory Nachod a.s. The results are supplemented by a simulation using software Maxwell RMxprt and finite element method (FEM). Finally, they are compared to each machines modifications mainly in terms of energy consumption.

The still increasing demand of electrical energy and the rising popularity of renewable energy sources in today's world are two important developments that necessitate the need for innovative solutions in the field of power electronics. Parallel operation of converters is one possible method in trying to bridge an increased current demand. The classical two-level converters, which are the standard in low voltage applications, are rarely adopted in medium and high voltage applications due to the voltage limits on power semiconductor devices. That is one reason for the growing popularity of multilevel converter topologies in medium and high-voltage applications. Although an increase in the number of voltage levels of a multilevel converter has its advantages, there are also challenges posed due to the increased number of switching devices. This has resulted in three-level converters being the most popular compared to converters of higher voltage levels. In this dissertation, the unified operation of parallel connected three-level converter units as a multilevel converter of higher voltage levels is proposed. The mathematical basis for operating parallel connected converter units as a single multilevel converter and the governing equations for such systems are derived. The analysis and the understanding of these equations are important for assessing practicality of the system and devising appropriate control structures. Parallel operation of converter units operating as multilevel converter have their own set of challenges, the two foremost being that of load-sharing and the possibility of circulating and cross currents. Developing solutions to address these challenges require a thorough understanding of how these manifest in the proposed system. Algorithms are then developed for tackling these issues. The control structures are designed and the developed algorithms are implemented. The operation of the system is verified experimentally. / Die weiterhin steigende Nachfrage nach elektrischer Energie und die zunehmende Verwendung erneuerbarer Energiequellen in der heutigen Welt sind zwei wichtige Entwicklungen, die die Notwendigkeit innovativer Lösungen im Bereich der Leistungselektronik erfordern. Der Parallelbetrieb von Stromrichtern ist eine mögliche Methode, um einen erhöhten Strombedarf zu decken. Der klassische Zweipunkt-Spanungszwischenkreisstromrichter, der bei Niederspannungsanwendungen weit verbreitet ist, wird aufgrund der Spannungsgrenzen für Leistungshalbleiterbauelemente zunehmend weniger in Mittel- und Hochspannungsanwendungen eingesetzt. Die begrenzte Spannungsbelastbarkeit der Leistungshalbleiterbauelemente ist ein Grund für die wachsende Beliebtheit von Mehrpunkt-Stromrichtertopologien in Mittelund Hochspannungsanwendungen. Obwohl eine Erhöhung der Anzahl der Spannungsstufen eines Mehrpunkt-Stromrichters Vorteile hat, gibt es auch Herausforderungen und Nachteile aufgrund der erhöhten Anzahl von Leistungshalbleitern. Dies hat dazu geführt, dass der Dreipunkt-Stromrichter die verbreiteste Topologie im Vergleich zu anderen Stromrichtern mit einer höheren Anzahl von Spannungsstufen ist. In dieser Dissertation wird der Betrieb von parallel geschalteten Dreipunkt-Stromrichtereinheiten als ein Mehrpunkt-Stromrichter mit erhöhter Anzahl an Spannungsstufen vorgeschlagen. Die mathematische Basis für den Betrieb von parallel geschalteten Stromrichtereinheiten als ein Mehrpunkt-Stromrichter und die beschreibenden Gleichungen eines solchen Systems werden abgeleitet. Die Analyse und das Verständnis dieser Gleichungen sind wichtig für die Beurteilung der Praktikabilität des Systems und die Erarbeitung geeigneter Regelstrukturen. Der parallele Betrieb von Stromrichtereinheiten hat seine eigenen Herausforderungen, wobei die beiden wichtigsten die Lastverteilung und die Möglichkeit von Kreis- und Querströmen sind. Die Entwicklung von Lösungen zur Bewältigung dieser Herausforderungen erfordert ein gründliches Verständnis dafür, wie sich diese Phänomene in dem vorgeschlagenen System manifestieren. Algorithmen zur Lösung dieser Probleme werden anschlieend entwickelt. Die Regelstrukturen werden entworfen und die entworfenen Algorithmen implementiert. Die Funktionsweise des Systems wird experimentell überprüft.

In order to meet the increasing demand for sustainable transportation, trains need to run with tighter schedules, more departures and more trains in depot. Multiple trains in depot has been linked to low frequency instability at many locations around the world. The instability originates in the interaction between the infrastructure and trains, specifically the line converter module (LCM). The phenomenon has been studied during the last two decades. Today there are a number of methods used to analyse low frequency stability, although these methods are usually slow and cumbersome. In this project a modelling approach is proposed for a linear small-signal DQ-frame admittance model of the LCM. The model describes the relationship of the low frequency oscillations between the line voltage and line current. Similar linear models have been derived previously, although the design of the specific train modelled is in part significantly different from the design of the trains modelled previously. The main difference is in the DQ-transformation for the phase locked loop (PLL), which in this thesis is implemented with a DFT-based method, and the implementation of the current controller (CC) which in this thesis is implemented in the stationary reference frame. The LCM and infrastructure (modelled as an impedance) is then analysed as a feedback loop using dominant poles analysis, regularly used in control theory. The result from the proposed model was evaluated using methods that are common in the industry. Furthermore, as the LCM is a complex system and the impact of different components and control parameters is not fully understood, the proposed model is used to examine how changing different parameters affect the overall stability of the system. The correlation between the results from the proposed model and the methods used for evaluation implies that the modelling approach is accurate. The two main benefits of the proposed model is that the method is much faster than most other methods for low frequency analysis, the proposed model is useful for testing different parameter configurations and changes in the design of the LCM. / För att möta den ökande efterfrågan på hållbar transport, behöver tåg idag köras med stramare tidtabeller, fler avgångar och fler tåg i depå. Flera tåg i depå har kopplats till lågfrekvent instabilitet på många platser runt om i världen. Instabiliteten har sitt ursprung i interaktionen mellan infrastrukturen och tågen, särskilt nätströmriktaren (LCM). Fenomenet har studerats under de senaste två decennierna. Idag finns det ett antal metoder som används för att analysera lågfrekvent stabilitet, dock är dessa metoder vanligtvis är långsamma och besvärliga. Detta projekt beskriver en modelleringsmetod lågfrekvenssvängningar mellan linjespänningen och linjeströmmen. Liknande linjära modeller har härletts tidigare, skiljer sig utformningen av det specifika tåget modellerad i denna avhandling från de tåg som modellerats tidigare i vissa design val. Den största skillnaden ligger i DQ-transformationen för den synkroniseringsregulatorn (PLL), som i denna avhandling är implementerad med en DFT-baserad metod, och implementeringen av strömregulatorn (CC) som i denna uppsats implementeras i den stationära referensramen. LCM tillsammans med infrastruktur (modellerad som en impedans) analyseras sedan som en stängd återkoppling där det stängda systemets poler härleds. Resultatet från den föreslagna modellen utvärderades med metoder som är vanliga i branschen. Dessutom, eftersom LCM är ett komplext system och effekten av olika komponenter och styrparametrar inte är helt förstod, används modellen för att undersöka hur förändringar i olika parametrar påverkar hela systemets stabilitet. Korrelationen mellan resultaten från det föreslagna modell och de metoder som används för utvärdering av lågfrekvent stabilitet idag innebär att modelleringsmetoden är lovande. De metoden är mycket snabbare än de flesta andra metoder för lågfrekvent analys och att den föreslagna modellen är användbar för att testa olika parameterkonfigurationer och förändringar i utformningen av LCM.

The EU has proposed an ambitious goal to achieve widespread E-mobility in both the electrical and commercial sectors. To accomplish this, a substantial number of DC fast-charging stations must be built. These power converters, installed in the DC fast-charging stations (DCFC), differ from traditional DCDC converters as they exhibit high power density, reaching tens of kilowatts. In contrast to traditional non-isolated power converters, isolated power converters offer ideal galvanic isolation, providing protection to both the local power grid and electric vehicles. Among the DC power converters designed for industrial applications, the LLC resonant converters and DAB converters (Dual Active Bridge) have gained significant popularity. When compared to LLC converters, DAB converters demonstrate a more flexible input and output power range, as well as a higher power density. Considering these advantages, a 10kW bidirectional DAB power converter has been designed for the purpose of fulfilling the requirements of this thesis project. The thesis is organized into four distinct parts. The first part focuses on conducting a comprehensive literature review to explore the challenges prevalent in the current electrical field. Various DC-DC topologies are compared based on different factors, including component analysis, controllability, safety considerations, and cost-effectiveness. By examining these aspects, potential solutions for Electric Vehicles (EVs) are identified. In the second part, a specific DC-DC converter with a power rating of 10kW is chosen, utilizing the DAB (Dual Active Bridge) topology. The selection is based on the analysis conducted in the literature review. The thesis delves into the issues and technical challenges associated with this choice, such as reactive power, peak current, zero-voltage switching (ZVS), and phase shift modulation. These topics are thoroughly explored and discussed within the literature study. The second part of the thesis involves the establishment of a DAB model, incorporating mathematical equations and physical derivations. This modeling and design section discusses the energy conversion process, starting from fundamental physical formulas and extending to the overall system setup. Utilizing the proposed model, a control method called SPS (Single Phase Shift) modulation is implemented in the circuit to achieve closed-loop control. Within this part, the relationship between current, voltage, and output power is derived and utilized for the design of a PI closed controller. To address challenges associated with SPS control, such as reactive power elimination and peak current suppression, an EPS (Enhanced Phase Shift) control scheme is introduced. The EPS control scheme not only fulfills the basic requirement of power transfer but also optimizes the system’s overall efficiency. In the third part of the thesis, a simulation is developed to validate the accuracy of the proposed DAB model and control methods. Simulations are implemented using Simulink, a widely used software for dynamic system modeling and simulation. Various aspects of the system are evaluated through the simulation, including the leakage inductor current, voltage waveforms on both the primary and secondary sides and output power. These parameters are plotted and analyzed to assess the performance of the DAB model and control methods. Additionally, loss and efficiency analyses are conducted using PLECS, a simulation platform that specializes in power electronics systems. By inputting the datasheet information of the switches and transformer, PLECS enables the evaluation of losses and efficiency within the system. This analysis provides valuable insights into the performance and energy efficiency of the proposed DAB-based converter. In the final part of the thesis, conclusions are drawn based on the theoretical findings and simulation results obtained throughout the study. These conclusions reflect the overall outcomes and implications of the research conducted. Furthermore, the future work section outlines the tasks that remain unfinished or areas that can be explored in subsequent studies. This section serves as a guide for future researchers, highlighting potential directions for further investigation and improvement in the field of DAB-based DC-DC converters for E-mobility applications. By presenting the conclusions and future work, the thesis provides a comprehensive summary of the research conducted, its contributions, and potential avenues for future research and development. / EU har föreslagit ett ambitiöst mål för att uppnå utbredd e-mobilitet inom både den elektriska och kommersiella sektorn. För att åstadkomma detta måste ett stort antal DC snabbladdningsstationer byggas. Dessa effektomvandlare, installerade i DC-snabbladdningsstationerna (DCFC), skiljer sig från traditionella DC-DC-omvandlare eftersom de uppvisar hög effekttäthet och når tiotals kilowatt. I motsats till traditionella icke-isolerade kraftomvandlare erbjuder isolerade kraftomvandlare idealisk galvanisk isolering, vilket ger skydd för både det lokala elnätet och elfordon. Bland likströmsomvandlarna som är designade för industriella applikationer har LLC-resonantomvandlarna och DABomvandlarna (Dual Active Bridge) vunnit betydande popularitet. Jämfört med LLC-omvandlare uppvisar DAB-omvandlare ett mer flexibelt in- och uteffektområde, såväl som en högre effekttäthet. Med tanke på dessa fördelar har en 10kW dubbelriktad DAB-effektomvandlare designats för att uppfylla kraven i detta examensarbete. Avhandlingen är organiserad i fyra distinkta delar. Den första delen fokuserar på att genomföra en omfattande litteraturgenomgång för att utforska de utmaningar som råder inom det nuvarande elektriska området. Olika DCDC-topologier jämförs baserat på olika faktorer, inklusive komponentanalys, kontrollerbarhet, säkerhetsöverväganden och kostnadseffektivitet. Genom att undersöka dessa aspekter identifieras potentiella lösningar för elektriska fordon (EV). I den andra delen väljs en specifik DC-DC-omvandlare med en märkeffekt på 10kW, som använder DAB-topologin (Dual Active Bridge). Urvalet baseras på den analys som gjorts i litteraturöversikten. Avhandlingen fördjupar sig i de problem och tekniska utmaningar som är förknippade med detta val, såsom reaktiv effekt, toppström, nollspänningsomkoppling (ZVS) och fasskiftsmodulering. Dessa ämnen utforskas och diskuteras grundligt inom litteraturstudien. Den andra delen av examensarbetet omfattar upprättandet av en DAB-modell, innefattande matematiska ekvationer och fysiska härledningar. Det här avsnittet om modellering och design diskuterar energiomvandlingsprocessen, med start från grundläggande fysiska formler och sträcker sig till den övergripande systemuppställningen. Genom att använda den föreslagna modellen implementeras en styrmetod som kallas SPS-modulering (Single Phase Shift) i kretsen för att uppnå sluten-loop-styrning. Inom denna del härleds förhållandet mellan ström, spänning och uteffekt och används för konstruktionen av en sluten PI-regulator. För att ta itu med utmaningar förknippade med SPS-kontroll, såsom eliminering av reaktiv effekt och undertryckning av toppström, introduceras ett EPS-kontrollschema (Enhanced Phase Shift). EPS-kontrollsystemet uppfyller inte bara det grundläggande kravet på kraftöverföring utan optimerar också systemets totala effektivitet. I den tredje delen av avhandlingen utvecklas en simulering för att validera noggrannheten hos den föreslagna DAB-modellen och styrmetoderna. Simuleringar implementeras med Simulink, en mycket använd programvara för dynamisk systemmodellering och simulering. Olika aspekter av systemet utvärderas genom simuleringen, inklusive läckans induktorström, spänningsvågformer på både primär- och sekundärsidan och uteffekt. Dessa parametrar plottas och analyseras för att bedöma prestandan hos DABmodellen och styrmetoderna. Dessutom genomförs förlust- och effektivitetsanalyser med hjälp av PLECS, en simuleringsplattform som är specialiserad på kraftelektroniksystem. Genom att mata in databladsinformationen för switcharna och transformatorn, möjliggör PLECS utvärdering av förluster och effektivitet i systemet. Denna analys ger värdefulla insikter om prestandan och energieffektiviteten hos den föreslagna DAB-baserade omvandlaren. I den sista delen av uppsatsen dras slutsatser baserat på de teoretiska fynden och simuleringsresultat som erhållits genom studien. Dessa slutsatser speglar de övergripande resultaten och konsekvenserna av den genomförda forskningen. Vidare skisserar det framtida arbetsavsnittet de uppgifter som förblir oavslutade eller områden som kan utforskas i efterföljande studier. Det här avsnittet fungerar som en guide för framtida forskare, och lyfter fram potentiella riktningar för ytterligare undersökningar och förbättringar inom området DAB-baserade DC-DC-omvandlare för e-mobilitetstillämpningar. Genom att presentera slutsatserna och det framtida arbetet ger avhandlingen en omfattande sammanfattning av den forskning som bedrivs, dess bidrag och potentiella vägar för framtida forskning och utveckling.

Η επιβάρυνση του φυσικού περιβάλλοντος από τους συμβατικούς τρόπους ηλεκτροπαραγωγής έστρεψε τα τελευταία χρόνια την παγκόσμια ενεργειακή πολιτική στην ανάπτυξη και βελτίωση μεθόδων ηλεκτροπαραγωγής βασισμένων σε Ανανεώσιμες Πηγές Ενέργειας (ΑΠΕ). Αν και η ενσωμάτωση των ΑΠΕ στο δίκτυο μέσης τάσης δε συνοδεύεται από ιδιαίτερες πρακτικές δυσκολίες, δεν συμβαίνει το ίδιο και με το ηλεκτρικό δίκτυο των αστικών περιοχών, εξαιτίας της δομής των σύγχρονων μεγάλων αστικών κέντρων. Λαμβάνοντας υπόψη ότι οι μεγάλοι καταναλωτές (εργοστάσια και βιομηχανίες) θεωρούνται κατά κοινή πρακτική ως σταθερά φορτία, γίνεται κατανοητό πως ο βαθμός ανάπτυξης των αστικών κέντρων διαδραματίζει πολύ σημαντικό ρόλο τόσο στη ζήτηση ηλεκτρικής ενέργειας όσο και στη διαμόρφωση της αιχμής της καταναλισκόμενης ισχύος. Στο Ελληνικό Σύστημα Ηλεκτρικής Ενέργειας οι μήνες κατά τους οποίους βάλλεται περισσότερο η επάρκεια του ηλεκτρικού συστήματος επικεντρώνονται στη διάρκεια της θερινής περιόδου. Από την άλλη πλευρά, η μέγιστη παραγωγή ηλεκτρικής ενέργειας από την ηλιακή συμπίπτει χρονικά με τις ημερήσιες αιχμές ζήτησης των καλοκαιρινών μηνών. Συνεπώς, η χρήση μικρών ευέλικτων φωτοβολταϊκών (Φ/Β) συστημάτων, που μπορούν να εγκατασταθούν τόσο σε κατοικίες, όσο και σε εμπορικά ή δημοσία κτίρια (Διασυνδεδεμένα κτιριακά Φ/Β συστήματα) μπορεί να συμβάλει τόσο στην εξομάλυνση των αιχμών φορτίου όσο και στη μείωση του συνολικού κόστους ηλεκτροπαραγωγής. Η τελευταία και νεώτερη τεχνολογική τάση στα διασυνδεδεμένα κτιριακά φωτοβολταϊκά συστήματα είναι γνωστή με τον όρο Φωτοβολταϊκά Πλαίσια Εναλλασσομένου Ρεύματος (Φ/Β Πλαίσια Ε.Ρ). Πρόκειται για Φ/Β διατάξεις μικρής ισχύος (έως 300W), οι οποίες δημιουργούνται από την ενσωμάτωση ενός μόνο Φ/Β πλαισίου και ενός μονοφασικού αντιστροφέα σε μια αυτοτελή ηλεκτρονική διάταξη. Σκοπός της παρούσας εργασίας είναι η συμβολή της στον τομέα των Φ/Β μονάδων διεσπαρμένης παραγωγής, με την αναζήτηση μιας διάταξης διασύνδεσης φωτοβολταϊκών γεννητριών μικρής ισχύος με το ηλεκτρικό δίκτυο των αστικών περιοχών. Συγκεκριμένα, διερευνάται η δυνατότητα ανάπτυξης μιας ηλεκτρονικής διάταξης με απομόνωση, η οποία αφ’ ενός μεν θα εξασφαλίζει υψηλό συντελεστή ισχύος και υψηλό βαθμό απόδοσης για ευρύ φάσμα λειτουργίας, αφ’ ετέρου δε θα διέπεται από μικρό βαθμό πολυπλοκότητας στο κύκλωμα ισχύος της προκειμένου να εξασφαλίζεται υψηλή αξιοπιστία. Επιπρόσθετα, ιδιαίτερα χαρακτηριστικά αυτής της διάταξης θα πρέπει να είναι ο μικρός όγκος και το μικρό βάρος, ιδιότητες πολύ σημαντικές εάν αναλογιστούμε τις εφαρμογές για τις οποίες προορίζεται (ενσωμάτωση σε Φ/Β γεννήτριες που θα τοποθετηθούν σε όψεις ή οροφές κτιρίων). Το ενδιαφέρον της εργασίας εστιάσθηκε στον υψίσυχνο αντιστροφέα ρεύματος τοπολογίας Flyback. Για τη διάταξη αυτή διερευνήθηκαν δύο διαφορετικές τεχνικές ελέγχου (οι οποίες οδηγούν σε διαφορετικές καταστάσεις λειτουργίας) και ελέγχθηκε η καταλληλότητα τους για διαφορετικά επίπεδα ισχύος. Για τις δύο αυτές τεχνικές ελέγχου αναπτύχθηκαν μαθηματικά μοντέλα που συνδέουν τη μεταφερόμενη στο δίκτυο ισχύ με τις κατασκευαστικές παραμέτρους του αντιστροφέα και εξήχθησαν κριτήρια για τα ασφαλή όρια λειτουργίας του αντιστροφέα, με γνώμονα την καταπόνηση των ημιαγωγικών στοιχείων ισχύος. Επιπλέον, προτάθηκε η συνδυασμένη εφαρμογή των δύο τεχνικών ελέγχου και παρουσιάστηκε μια στρατηγική σχεδιασμού του αντιστροφέα, ώστε να γίνεται βέλτιστη επιλογή όλων των επιμέρους λειτουργικών του στοιχείων με ταυτόχρονη ελαχιστοποίηση του όγκου του, επίτευξη υψηλού συντελεστή ισχύος καθώς και υψηλού βαθμού απόδοσης, για ευρύ φάσμα της παραγόμενης ισχύος. Τέλος, διερευνήθηκε η δυνατότητα ανάπτυξης ενός ενεργού φίλτρου, για την αποτελεσματική εξομάλυνση της έντονης κυμάτωσης του ρεύματος εισόδου του προτεινόμενου αντιστροφέα. Η κυμάτωση αυτή είναι αποτέλεσμα της τροφοδότηση του μονοφασικού ηλεκτρικού δικτύου Ε.Ρ. από τη συνεχή τάση και το συνεχές ρεύμα που παράγουν οι φωτογεννήτριες και ο περιορισμός της είναι ιδιάζουσας σημασίας προκειμένου να καταστεί δυνατή η αποδοτική λειτουργία της όλης διάταξης. Η λειτουργία του προτεινόμενου ενεργού φίλτρου είναι ανεξάρτητη τόσο των καταστάσεων λειτουργίας του αντιστροφέα τύπου Flyback, όσο και γενικότερα της τοπολογίας του αντιστροφέα, καθιστώντας την έτσι ως μια ελκυστική λύση και για διαφορετικές τοπολογίες μετατροπέων. Η ακρίβεια των μαθηματικών μοντέλων, η ορθότητα της προτεινόμενης στρατηγικής σχεδιασμού και η αποτελεσματικότητα του προτεινόμενου ενεργού φίλτρου επιβεβαιώθηκαν μέσω προσομοίωσης και πειραματικών δοκιμών, ενώ τέλος παρατίθενται τα συμπεράσματα από το σύνολο της εργασίας. Η εργασία αυτή συγχρηματοδοτείται κατά: 80% της Δημόσιας Δαπάνης από την Ευρωπαϊκή Ένωση – Ευρωπαϊκό Κοινωνικό Ταμείο, 20% της Δημόσιας Δαπάνης από το Ελληνικό Δημόσιο – Υπουργείο Ανάπτυξης – Γενική Γραμματεία Έρευνας και Τεχνολογίας και από τον Ιδιωτικό Τομέα, στο πλαίσιο του Μέτρου 8.3 του Ε.Π. Ανταγωνιστικότητα – Γ΄ Κοινοτικό Πλαίσιο Στήριξης. / The aggravation of natural environment from the conventional ways of electricity generation turned during past few years the worldwide energy policy to the development and the improvement of electricity generation methods based on Renewable Energy Sources (RES). Although the interconnection of RES in the medium voltage network is not accompanied by particular practical difficulties, this is not the case for the electric network of urban regions, by reason of the structure of modern big urban centres. Taking into consideration that in common practice the big consumers (factories and industries) are considered as constant loads, it becomes comprehensible that the growth of urban centres plays very important role both in the demand of electrical energy and the formation of peak electricity power consumption. Τhe time period where the sufficiency of the Greek Electric Energy System is threatened is during the aestival period. On the other hand, the peak electricity production from solar energy coincides with the daily peak consumption of summer months. Consequently, the use of small flexible photovoltaic (PV) systems, installed in residences or in commercial and public buildings (BIPV – Building Integrated Photovoltaic’s), can contribute to the normalisation of electrical energy consumption as well as to the reduction of electricity generation total cost. The latest technology on small scale grid-connected residential PV systems is the Alternative Current Photovoltaic Modules (AC-PV Modules) where the power production varies under 0.3kW. An AC-PV Module is the combination of a single PV module and a single-phase power electronic inverter in a single electrical device. The scope of the present work is to contribute in the sector of the Dispersed Power Generation PV systems, with the development of an inverter that will be used for the interconnection of small PV generators with the electric network of urban regions. In more details, the development of an inverter with electrical isolation is investigated, which on the one hand it will ensure high power factor regulation and high efficiency for wide power range and on the other hand it will be characterised by simple power electronic circuit structure in order to ensure high reliability. Moreover, particular characteristics of this inverter should be the small volume and the small weight, attributes very important considering its applications (incorporation in PV generators that will be placed in aspects or roofs of buildings). The interest of present work is focused in the high frequency current source Flyback inverter. For this topology two different control techniques were investigated, leading to different operation modes. Moreover, their suitability is studied for different power levels. For both control techniques mathematic models were developed, connecting the transferred power in the public grid with the inverter operational parameters, as well as criteria for the inverter safe operation area were exported, considering the acceptable peak voltage and current values for the semiconductor switches. Moreover, the combined application of two control techniques is proposed and an optimum inverter design strategy is presented, aiming to the development of an inverter with the smallest possible volume, as well as to the achievement of high power factor regulation and high efficiency for wide power range. Last but not least, a current pulsation smoothing active filter is investigated and developed, which permits the elimination of the low frequency inverter input current. The current pulsation is a result of the power pulsation, due to the single-phase power generation, and its elimination is of great importance in order to exploit the maximum PV generated electricity power. The active filter configuration is independent from the inverter topology and its operation mode and hence it can be applied for various single stage topologies. The precision of the mathematic models, the correctness of the proposed design strategy and the effectiveness of the proposed active filter are validated via simulation and experimental results. Finally, the conclusions of whole study are exhibited. This thesis is part of the 03ED300 research project, implemented within the framework of the “Reinforcement Programme of Human Research Manpower” (PENED) and cofinanced by National and Community Funds (20% from the Greek Ministry of Development-General Secretariat of Research and Technology and 80% from E.U.- European Social Fund).