In this thesis, an alternative solution for designing power line conductive electromagnetic interference (EMI) filter by using the consecutive orthogonal array method is proposed. The circuit parameters of EMI filters to be determined are assigned as the control variables in the orthogonal arrays, and the average effects corresponding to each control variable are calculated from the measured results. In accordance with the inferential rules, the average effects are used as the observational indices to adjust the levels of the control variables of the subsequent orthogonal array. Through manipulating consecutive orthogonal arrays step by step, the applicable ranges of circuit parameters are approached with desired output performances. Finally, the component values of EMI filters with minimum size can be found. The design procedure and the inferential rules are described by illustrative examples for a single-stage high-power-factor converter.

The metal halide lamp has become an attractive lighting source because of its compact size, good color rendering, long lamp life, and high luminous efficacy. As a member of high-intensity discharge lamps, it has a negative incremental resistance, which claims the necessity of a ballast circuitry. Similar to other gas discharge lamps, the operating performance can be further improved when driven by a high-frequency electronic ballast. However, there are some obstacles in ballasting the metal halide lamp with the high-frequency inverter. For a cold lamp, an ignition voltage up to several kVs is required for breaking down the electrodes during starting period. The breakdown voltage and the equivalent lamp resistance may vary from time to time and lamp to lamp, and is sensitive to the used time. Furthermore, the ignition voltage for restarting a hot lamp can be ten times that for a cold lamp. On the other hand, the lamp driven by a high-frequency electronic ballast may suffer from acoustic resonance. All these make it difficult in the design of an electronic ballast, especially for the applications with hot restarting. In this dissertation, the operating characteristics for both starting transient and steady-state of the metal halide lamp are first investigated. Then, a simple method by measuring the lamp voltage is proposed to detect the happening of acoustic resonance. Based on the investigated results, several electronic ballasts are designed for driving metal halide lamps with capabilities of wide input voltage range, high input power factor, hot restarting, fast transition. In addition, an inverter circuit is configured for ballasting multiple lamps. A buck-boost power-factor-correction circuit is integrated into the load resonant inverter to achieve a high power factor, fast transition, and constant power operation. The extremely high ignition voltage for hot restarting is generated by an auxiliary ignitor. The electronic ballast is precisely operated at the specific frequency at which acoustic resonance will not occur. In addition to these features, a protection circuit is included to prevent from high voltage and/or current stresses on circuit components in case that the lamp fails to be started up or comes to the end of its life-time. For the ballast with multiple lamps, the load circuits with abnormal lamps can be isolated from the others which are under normal operation. Prototypes of the proposed circuits are built and tested. Experimental results present the satisfactory performances.

A single-stage high-power-factor electronic ballast with class E inverter is proposed for driving the fluorescent lamp. The circuit configuration is obtained from the integration of a buck-boost converter for power-factor- correction (PFC) and a class E resonant inverter for ballasting. The integrated ballast circuit requires only one active power switch and simple control. Operating the buck-boost converter in discontinuous conduction mode (DCM) at a fixed frequency, the electronic ballast can achieve nearly unity power factor. With pulse-width-modulation (PWM), the electronic ballast can provide an appropriate filament current for preheating, a high voltage for ignition, and then a desired lamp current for steady-state operation. An additional control circuit is included to eliminate the glow current during preheating stage. The operation of the ballast-lamp circuit is analyzed by fundamental approximation. Computer simulations are made and design equations are derived on basis of the power-dependent resistance model of the fluorescent lamp. With carefully designed circuit parameters, the active power switch can be switched on at zero current to reduce the switching losses leading to a higher efficiency. An experimental circuit designed for a PL-27W compact fluorescent lamp is built and tested to verify the computer simulations and analytical predictions. Experimental results show that satisfactory performances can be obtained on the proposed electronic ballast.

This thesis proposes a single-stage high-power-factor electronic ballast with series-resonant inverter for rapid-start fluorescent lamps with zero glow current during preheating period. A buck-boost converter is integrated into the ballast as the power-factor-corrector. Two auxiliary windings are wound on the same core of the buck-boost inductor for filament heating. During the preheating period, the buck-boost converter is initiated while the series-resonant inverter is disabled by controlling the corresponding active power switches. Due to zero voltage across the lamp, the glow current can be effectively eliminated. As the filaments reach appropriate emission temperature, the series-resonant inverter is activated. The lamp is then ignited and consequently operated at the rated lamp power. Circuit analyses and experimental tests of the proposed preheating control scheme are carried out on an electronic ballast for a T8-40W rapid-start fluorescent lamp.

The modern society uses more and more electronic devices needed to being able to function together. This put higher demands on the electrical grid together with that the typical load have changed from the past. Therefore utility companies are obliged to keep the voltage within certain limits for this to function. What exact these limits have been have not always been clear since they have not been gathered in one single document.  This thesis is a cooperation with Kraftringen who also has been the initiator. Kraftringen would like to become more proactive in their work regarding electric power quality. For becoming more proactive continuously measurements have to be done but the locations have to be carefully selected in the beginning to get a wider perspective of the grid. Energy markets inspectorate (EI) is supervisory of the electric power quality in Sweden and since 2011 they have published a code of statutes (EIFS 2011:2 later 2013:1) intended to summarize limits on voltage. Some of the electrical power quality aspects are not mentioned in EIFS 2013:1 and standards have to be used to find limited values. Flicker and interharmonics are not mentioned in EIFS 2013:1 and for values on flicker the standard SS-EN 50160 has to be used and for interharmonics the standard SS-EN 61000-2-2 state limit values. Besides all this there are standards with stricter limits than EIFS 2013:1 e.g. for total harmonic distortion on voltage were SS-EN 61000-2-2 suggest 6 % instead of 8 %. Three different field studies have been conducted in order to get some perception of the present situation regarding electric power quality. Two measurements were conducted on a typical office building because they represents a large part of the typical load in Lund. The third measurement was conducted on a substation in a rural area to get a perception of the situation outside urban areas.  These measurements shown that the overall electric power quality was within given limits according to EIFS 2013:1 and different standards. However, conducted measurements shown some interesting results. Both the typical office buildings have a slightly capacitive power factor which results in that the voltage inside the building is going to be slightly higher than at the substation. Since the voltage level at the measured urban substation was above nominal voltage level with about 2-5 % this could be problematic. Another eventual problem with a load with a capacitive power factor is resonance with the inductive parts of the grid like transformers leading to magnified harmonic levels. It is suggested that Kraftringen expand their number of permanent electric power quality measurement locations to get a better overview of the present situation. The best suited locations to start with are such that have received complaints earlier, preferably measured on the low voltage side of the transformer for also register the amount of zero sequence harmonics. Next step in the measurement expansion would be substations known to be under higher load than others or substations with a PEN-conductor in a smaller area than the phase conductors, supplying a typical office load with high amounts of third harmonics and unbalance. From this it would be appropriate to spread out the measurement locations geographically to better get to know the grids behaviour.

The study reviews and examines the definitions of reactive power, apparent power, and power factor. Among the different definitions of power factor in three-phase circuits under a non-sinusoidal condition, this study adopts the definition of the effective power factor, which is also advocated by IEEE Standard 1459-2010. The effective power factor is defined as the ratio of the real power consumed by the load over the effective apparent power. The effective apparent power is the maximum power transmitted to the load (or delivered by a source) while keeping the same line losses and the same load (or source) voltage and current. The effective power factor theory gives apparent power a definite physical significance and provides more insights than other definitions in unbalanced circuits. Another merit of the effective power factor definition is that it only involves measurements and computations in the time domain. This study implements the computation of the effective power factor in MATLAB for use in PSCAD/EMTDC. The latter simulates the power system and provides three-phase voltage and current measurements. MATLAB performs the effective power factor computation and sends the results back to PSCAD. A number of simulations are provided in this report to demonstrate the validity and the accuracy of this implementation. / text

Η παρούσα διπλωματική εργασία πραγματεύεται το σχεδιασμό και την κατασκευή ενός μετατροπέα ανόρθωσης και υποβιβασμού τάσης, με διόρθωση του συντελεστή ισχύος. Η χρήση αυτού του μετατροπέα προορίζεται για τη φόρτιση των μπαταριών ενός ηλεκτροκίνητου οχήματος. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Κύριος σκοπός της διπλωματικής εργασίας είναι η κατασκευή μιας τριφασικής ανορθωτικής διάταξης υποβιβασμού τάσης η οποία θα πληρεί τις προδιαγραφές περί αρμονικών που θεσπίζονται από τους διεθνείς κανονισμούς. Η δυνατότητα λειτουργίας υπό μοναδιαίο συντελεστή ισχύος πηγάζει από τη μεθοδολογία ελέγχου του μετατροπέα ο οποίος παράλληλα θα πρέπει να επιτελεί το έργο ενός φορτιστή μπαταριών προσφέροντας τη δυνατότητα ελέγχου του ρεύματος και της τάσης εξόδου και προσαρμόζοντας τη λειτουργία του στο εκάστοτε προφίλ φόρτισης των μπαταριών τις οποίες διαχειρίζεται. Αρχικά αναλύεται η σημασία της διόρθωσης του συντελεστή ισχύος στα σύγχρονα ηλεκτρικά συστήματα και παρουσιάζονται τόσο μεθοδολογίες ελέγχου όσο και ανορθωτικές διατάξεις για λειτουργία υπό μοναδιαίο συντελεστή ισχύος. Στη συνέχεια γίνεται μια σύντομη αναφορά στις μπαταρίες ως μέσο αποθήκευσης ενέργειας, παρουσιάζονται μέθοδοι και διατάξεις φόρτισης συσσωρευτών ενώ παράλληλα αναλύονται θέματα που αφορούν την ταχύτητα φόρτισης και την διάρκεια ζωής των μπαταριών με τελικό στάδιο την παρουσίαση των μπαταριών του ηλεκτροκίνητου οχήματος του εργαστηρίου και την επιλογή του κατάλληλου προφίλ φόρτισής με βάση τα τεχνικά χαρακτηριστικά και τις προδιαγραφές τους από τον κατασκευαστή. Το επόμενο βήμα είναι η παρουσίαση του τριφασικού μετατροπέα, που θα υλοποιεί το προφίλ φόρτισης που έχει επιλεγεί, αλλά και της μεθοδολογίας ελέγχου για επίτευξη ημιτονοειδούς ρεύματος εισόδου. Τόσο ο ηλεκτρονικός μετατροπέας ισχύος ως φορτιστής μπαταριών όσο και το κύκλωμα ελέγχου κλειστού βρόχου προσομοιώνονται στο λογισμικό Simulink του Matlab. Επίσης περιγράφονται η ανάλυση, ο σχεδιασμός και η κατασκευή όλων των ηλεκτρικών και ηλεκτρονικών κυκλωμάτων που απαιτούνται για την ορθή λειτουργία του μετατροπέα και παρουσιάζεται η λογική λειτουργίας του μικροϋπολογιστικού συστήματος που συντονίζει τον έλεγχο. Τέλος πραγματοποιούνται οι πειραματικές δοκιμές προκειμένου να διαπιστωθεί η ορθή λειτουργία του συνολικού συστήματος που κατασκευάστηκε αλλά και για να διαπιστωθούν τυχούσες αποκλίσεις μεταξύ θεωρίας και πράξης. / This diploma thesis deals with the design and construction of a buck type, unity power factor rectifier intended for electric vehicle battery charging. The work was conducted in the Electromechanical Energy Conversion Laboratory, placed at the Department of Electrical and Computer Engineering of the University of Patras. The main purpose of this thesis is to construct a three-phase buck-type rectifier which meets with the requirements for low input current harmonics established by international regulations. The ability to operate under unity power factor derives from the control method of the converter. The converter will be also performing the task of a battery charger. Therefore, the overall system should be able to provide control of the output voltage and current and adjust its operation to the charging profile and the type of the battery used. Initially, the significance of power factor correction in modern electrical systems is mentioned and control methods as well as the most commonly used rectifiers for unity power factor operation are presented. Then, a brief reference to the batteries as energy storage means is made and charging methods and devices are presented. Certain issues related to charging speed and battery life are approached. The final stage is the presentation of the batteries installed in the electric vehicle of the Laboratory and the selection of the appropriate charging profile based on the technical specifications of the manufacturer. The next step is the presentation of the three-phase rectifier which realizes the selected charging profile and the control method in order to achieve sinusoidal input currents .Both the electronic power converter as a battery charger and the closed-loop control circuit are simulated using Simulink of Matlab .The analysis, design and the construction of all electrical and electronic circuits required for the proper operation of the converter is described and the programming logic of the microcontroller that coordinates the control is presented. Finally, experimental tests are performed in order to check the proper functioning of the overall constructed system and detect any deviations between theory and practice.

No description available.

Due to its unique features such as controllable power factor, controllable bi-directional power flow, and rapid dynamic response, Voltage Source Converters (VSCs) have been widely used in various industrial applications such as distributed generation systems, power distribution systems, uninterruptible power supplies (UPS), AC motor drives, etc. To optimize the performance of the VSC, many control algorithms have been proposed. This thesis investigates development of the nonlinear control for the VSC in two applications: power factor control and active power filtering. A detailed description of the dynamic model of the VSC system is presented in different reference frames. A linearization-based control scheme is introduced for power factor regulation and verified by switched simulation and real-time experiment on a test stand which has been constructed at the Applied Nonlinear Control Lab (ANCL), University of Alberta. In addition, an internal model-based control scheme is introduced to perform active power filtering. This algorithm is verified by simulation. / Controls

Orientador: Falcondes José Mendes de Seixas / Resumo: A utilização de conversores com baixa distorção harmônica na corrente de entrada melhora significativamente o fator de potência de equipamentos e instalações elétricas. Este trabalho apresenta a proposta de desenvolvimento de um conversor multipulso com estágio CC-CC SEPIC, que apresenta baixa distorção na corrente de entrada, regulação da tensão na saída, podendo ainda apresentar isolamento em alta frequência. Propõe-se a utilização do conversor proposto em aplicações industriais em inversores para acionamento de máquinas elétricas de corrente alternada, em substituição aos retificadores convencionais, técnica conhecida como retrofit, em barramentos CC regulados, fontes de tensão CC, entre outras aplicações. O conversor é baseado em um autotransformador não isolado de 18 pulsos, que disponibiliza três saídas trifásicas independentes e apresenta reduzido peso e volume quando comparados com os tradicionais transformadores isolados. Este conversor já apresenta significativa melhoria no fator de potência, porém não possibilita a regulação da tensão na saída, que dependerá unicamente da tensão de entrada, estando sujeita às variações que nela ocorram. As saídas independentes, após retificação, devem ser conectadas para poder alimentar a carga. A forma mais comum de possibilitar essa conexão é utilizando elementos magnéticos adicionais, chamados de transformadores interfase (IPTs). A utilização de conversores CC-CC é outra forma de realizar a conexão, resultando em um estágio CC-C... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Converters with low harmonic distortion of input current can improve significantly the power factor at electrical equipment and plants. This work proposes the development of a multipulse converter with DC-DC SEPIC stage, with low distortion in the input current, and may also provide high frequency isolation. It could be used in industrial applications to replace conventional rectifiers in Adjustable Speed Drives (ASDs), a technique known as retrofit. It can be used also in regulated DC bus, DC voltage power supply, among other applications. The converter is based on a non-isolated 18-pulse autotransformer that provides three independent three-phase outputs and has reduced weight and size. The autotransformer improves the power factor, but does not allow the regulation of the load voltage output. The independent outputs must be connected to the load. The most common way of providing this connection is by using additional magnetic elements, called interphase transformer (IPTs). The use of DC-DC converters is another way to perform the outputs connections, resulting in a DC-DC stage that control the voltage and current, thus enabling parallel connect loads. In this work, the SEPIC converter was selected, because it can be used with few modifications to the original structure. SEPIC converter can easily be isolated, allowing the use of multipulse converters in applications that require isolation between power supply and load. Prototypes with isolated and non-isolated SEPIC conver... (Complete abstract click electronic access below) / Doutor