Orientador: Helmo Kelis Morales Paredes / Resumo: Esta dissertação de mestrado propõe o desenvolvimento e a implementação de uma estratégia de compensação para conversores eletrônicos de potência (CEP) multifuncionais conectados à rede elétrica. A geração dos sinais de referência de corrente para o conversor multifuncional é obtida através das grandezas conservativas da CPT, do inglês Conservative Power Theory. O CEP proposto neste trabalho desempenha o papel de um conversor interface de rede no modo conectado, tendo como finalidade a mitigação de oscilações de potência instantânea bem como injeção de potência ativa na rede elétrica, caracterizando assim o seu aspecto multifuncional. São realizados estudos teóricos e simulações computacionais com o intuito de validar a estratégia proposta. Para tanto, foram identificadas as parcelas indesejadas de corrente que permitam a compensação das componentes oscilatórias da potência instantânea e da energia reativa instantânea da CPT. O CEP é controlado em modo corrente, através da estratégia de modulação PWM com duas malhas de controle. A estratégia de compensação e o sistema de controle serão avaliados e testados via simulação para diferentes configurações de cargas, incluindo uma carga não-linear desbalanceada operando em condições onde as distorções e desequilíbrios de tensão sejam consideráveis. Por fim, resultados experimentais obtidos com um protótipo em escala laboratorial são utilizados para validar a estratégia de compensação proposta / Abstract: This master’s thesis proposes the development and implementation of a compensation strategy for the three-phase multifunctional grid-tied inverter. The reference signal generation method for grid-tied is based on the Conservative Power Theory (CPT). In this work, the multifunctional inverter plays the role of the Utility Interface (UI) which perform several functions: in grid-connected operation, it injects active power into the grid and compensates the instantaneous power oscillation and the instantaneous reactive energy oscillation. The goal is to execute theoretical studies and computational simulations to validate the proposed strategy. For this purpose, firstly are identifies the unwanted currents which allow the compensation of the oscillatory terms of instantaneous power and reactive energy. The inverter is controlled in current mode through PWM modulation strategy with two control loops. In addition, the proposed compensation strategy and control system is evaluated and tested for different load configurations, such as linear and nonlinear loads (balanced and unbalanced) operating under different voltage conditions (distorted and unbalanced). Finally, experimental results are presented to validate the effectiveness and performance of the proposed compensation strategy. / Mestre

Multilevel Random Pulse Width Modulation (RPWM) schemes have drawn increasing attention in the past few years. Multilevel topologies provide high voltage and high power capabilities and random PWM schemes offer reduction in discrete harmonics spectral. This dissertation provides a generalized theory and analysis methods of the standard five-level Weighted RPWM (WRPWM). Equations have been derived to analyze the spectral performance and average switching frequency of the WRPWM output waveform using statistical approach. A modified WRPWM scheme has been proposed. The modified WRPWM scheme is then analyzed with the equations derived from the same approach. The analyzed theoretical spectrum of the standard five-level WRPWM is then compared with the three-level WRPWM scheme and the conventional carrier based PWM scheme. A scaled laboratory prototype diode clamping five-level inverter has been built for verification of the standard and the proposed modified WRPWM schemes. It can be seen that the experimental measurements and the theoretical analyzed results are all in good agreement. Results show the two five-level WRPWM schemes offers significant improvements on the spectrum content than the conventional carrier based PWM scheme. It was found that the five-level WRPWM schemes have successfully suppress the magnitude of third harmonic below 5% of the magnitude of fundamental component and even less for the higher order harmonic components. Research contributions made by the dissertation are: - The proposed modified multilevel WRPWM scheme which utilizing the switching decision redundancy of multilevel inverter to manipulate the harmonic content of the output signal. - The derived mathematical equations of the standard and modified five-level WRPWM scheme for analytical purposes. / Dissertation (MEng (Electrical Engineering))--University of Pretoria, 2005. / Electrical, Electronic and Computer Engineering / unrestricted

This thesis is concerned with the generation control in small isolated power systems consisting of inverter interfaced generation systems. First the components of an individual distributed generation system (DGS) as well as the corresponding control schemes for active and reactive power flow are discussed and implemented. Then the contribution of multiple DGS to meet the requirement of the loads in both gridconnected and island operations are discussed. Having evaluated the performance of each developed model such as voltage source inverter, PQ and PV controlled as well as reference DGS, the impact of voltage degradation on power load control in isolated systems is analyzed. Finally a new method for generation control in a small power system based on power sharing between multiple DGS with voltage degradation consideration as the last alternative for sustaining the system is proposed and implemented.-11D

As part of Nigeria’s drive to increase electricity production capacity and shift to renewable sources, a new 50 MW photovoltaic (PV) plant is proposed for a town in north-west Nigeria. Rather than using conventional monofacial modules and fixed mounting, it is of interest to consider a selection of new technologies which are attracting growing attention in the global utility PV market. These can increase energy output, and could be used to advantage in this 50 MW plant. However, the technologies, namely bifacial modules and solar tracking, are more expensive than their conventional counterparts, while their relative performance depends on the latitude and climate of the plant location. Thus their economic benefit cannot be taken for granted. The aim of this study is to propose multiple designs for the 50 MW plant using different combinations of module and mounting technologies, finding their economic order of merit by estimating their respective levelised costs of electricity (LCOEs).Using the simulation software PVsyst, the electricity production of different plant layouts and component configurations was estimated. Key parameters such as tilt angle and pitch distance were varied in order to optimise each configuration of technologies. Having sourced economic data from the industry and literature, lifetime plant costs were calculated, which in combination with lifetime electricity production, were used to estimate the LCOE.As expected, results indicated that the optimum configuration was bifacial modules mounted on horizontal single-axis tracking (SAT), followed by monofacial modules on horizontal SAT. Fixed installations had greater LCOEs by a reasonable margin, while the LCOE difference between monofacial and bifacial modules on fixed mounting was within the error of the calculation, meaning this choice relies on more accurate input data. A sensitivity analysis allowed uncertainty in the results to be gauged, and highlighted the factors which most influence LCOE, so that efforts to increase profitability can be focussed in the right places. Finally, suggestions are offered to help optimise bifacial and tracking installations by comparison with conventional plants.The conclusions drawn herein will be specifically relevant to the Swedish developer and EPC contractor Svenska Solenergigruppen which, in due course, will submit a plant design proposal to the project developer of the 50 MW plant. However, it is hoped that this work will act as a guide for any EPC contractor or developer working on a utility PV plant in sub-Saharan Africa, allowing efficient design of an optimal system.

<p>Recent developments in semiconductor device technology have seen the advent of wide-bandgap (WBG) based devices that enable operation at high switching frequencies. These devices, such as silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs), are becoming a favored choice in inverters for electric drive systems because of their lower switching losses and higher allowable operating temperature. However, the fast switching of such devices implies increased voltage edge rates (high <i>dv/dt</i>) that give rise to various undesirable effects including large common-mode currents, electromagnetic interference, transient overvoltages, insulation failure due to the overvoltages, and bearing failures due to</p> <p>microarcs. With increased use of these devices in transportation and industrial applications, it is imperative that accurate models and efficient simulation tools, which can predict these high-frequency effects and accompanying system losses, be established. This research initially focuses on establishing an accurate wideband model of a surface-mount permanent-magnet</p> <p>ac machine supplied by a WBG-based inverter. A new multirate simulation framework for predicting the transient behavior and estimating the power losses is then set forth. In this approach,</p> <p>the wideband model is separated into high- and low-frequency models implemented using two different computer programs that are best suited for the respective time scales. Repetitive execution of the high-frequency model yields look-up tables for the switching losses in the semiconductors, electric machine, and interconnecting cable. These look-up tables are then incorporated into the low-frequency model that establishes the conduction</p> <p>losses. This method is applied to a WBG-based electric drive comprised of a SiC inverter and permanent-magnet ac machine. Comparisons of measured and simulated transients are provided.</p>

Stand der Technik sind IGBTs und Freilaufdioden aus Silizium (Si). Jahrzehntelange Forschung hat zu einer nahezu perfekten Technologie geführt. Jedoch werden die Fortschritte hinsichtlich der Reduzierung von Schalt- und Durchlassverlusten mit jeder neuen Generation von Si-IGBTs immer kleiner. Die anfallende Verlustleistung kann jedoch signifikant mit Leistungshalbleiter-Bauelementen aus Siliziumkarbid (SiC) und Galliumnitrid (GaN) gesenkt werden. Ziel dieser Arbeit ist es, zu untersuchen, ob und inwieweit mit diskreten SiC-Bipolartransistoren im TO-247- und SiC-Schottky-Dioden im TO-220-Gehäuse der Wirkungsgrad eines Antriebsstromrichters gesteigert werden kann. Ein Exkurs in die Siliziumkarbid-Halbleitertechnologie am Anfang soll deren Vorteile in Hinblick auf verlustärmere Leistungselektronik aufzeigen. Die Vorteile des Halbleitermaterials Siliziumkarbid werden anhand des SiC-Bipolartransistors im Vergleich zum ersten Leistungstransistor - dem Bipolartransistor aus Silizium - herausgearbeitet. Beim SiC-Bipolartransistor muss im laststromführenden Zustand ein Steuerstrom in die Basis eingeprägt werden. Damit erhöht sich der Treiberaufwand. Deshalb wird der erste Themenschwerpunkt auf den Treiber gelegt. In dieser Arbeit wurden ein einfacher und ein komplexer Treiber aufgebaut und evaluiert. Mit leichten Modifikationen wurden mit dem komplexeren Treiber auch IGBTs und SiC-MOSFETs für Vergleichsmessungen angesteuert. Ein neuer Ansatz zur Reduzierung der Treiberverlustleistung im Wechselrichter mit SiC-Bipolar-Transistoren wird vorgestellt. Er setzt beim Kommutierungsalgorithmus des Wechselrichters an. Ein wesentlicher Teil der Arbeit widmet sich der Charakterisierung des SiC-Bipolartransistors, insbesondere dem Schaltverhalten. Ein- und Ausschaltwärmen für verschiedene Arbeitspunkte werden ermittelt. Am Ende der Arbeit werden experimentelle Untersuchungen an einem SiC-Wechselrichter durchgeführt. Abschließend werden die Potenziale, die mit dem Einsatz von SiC-Bipolartransistoren verbunden sind, bewertet aber auch die Grenzen aufgezeigt.:1 Einleitung 1 2 Aufbau des SiC-Bipolartransistors 2.1 Siliziumkarbid (SiC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.1 Eigenschaften von monokristallinem Siliziumkarbid . . . . . . . . . . 5 2.1.2 Herstellung des SiC-Wafers . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.3 Herstellung des SiC-Bipolartransistors . . . . . . . . . . . . . . . . . . 10 2.1.4 Defekte im Siliziumkarbidkristall . . . . . . . . . . . . . . . . . . . . 11 2.2 Halbleiterphysikalische Grundlagen . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.1 Gesperrter pn-Übergang . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.2 Stromführender pn-Übergang . . . . . . . . . . . . . . . . . . . . . . . 15 2.3 Bipolartransistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.1 Aufbau und Funktionsprinzip . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.2 Sperrfähigkeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.3.3 Erster und zweiter Durchbruch . . . . . . . . . . . . . . . . . . . . . . 23 2.3.4 Stromverstärkung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.3.5 Ladungsträgermodulation . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.3.6 Eindimensionaler spezifischer Widerstand der Driftzone . . . . . . . . 30 3 Ansteuerung des SiC-Bipolartransistors 3.1 Einführung Treiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.2 Herausforderungen beim Ansteuern von SiC-Bipolartransistoren . . . . . . . . 34 3.3 Treiberkonzepte für SiC-Bipolartransistoren . . . . . . . . . . . . . . . . . . . 36 3.4 Konventioneller Treiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.5 3-Level-Treiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.6 Treiber für SiC-MOSFET und IGBT . . . . . . . . . . . . . . . . . . . . . . . 45 4 Reduzierung der Treiberverluste durch Einschrittkommutierung 4.1 Einschrittkommutierung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.2 Stromvorzeichenerkennung . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4.3 Berechnung der Verlustleistungen für den eingeschalteten Zustand des SiC- Bipolartransistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.4 Messung der Treiberverlustleistung . . . . . . . . . . . . . . . . . . . . . . . . 52 5 Charakterisierung des SiC-Bipolartransistors 5.1 Messaufbau für Untersuchung des Ein- und Ausschaltverhaltens . . . . . . . . 55 5.2 Doppelpulsverfahren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 5.3 Definition der Schaltzeiten und Schaltverlustleistung . . . . . . . . . . . . . . 57 5.4 Messung der Schaltwärme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.4.1 Spannungstastköpfe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.4.2 Stromsensoren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 5.4.3 Zeitliche Verschiebung der Messsignale . . . . . . . . . . . . . . . . . 62 5.4.4 Vergleich von konventionellem und 3-Level-Treiber . . . . . . . . . . . 65 5.4.5 Vergleich bei unterschiedlicher Treiberspannung . . . . . . . . . . . . 66 5.4.6 Vergleich bei halb und voll bestückter Halbbrücke . . . . . . . . . . . . 68 5.4.7 Vergleich von SiC-Bipolartransistor mit SiC-MOSFET und Si-IGBT . . 69 5.4.8 Reduzierung der Spannungsspitze beim Ausschalten . . . . . . . . . . 74 5.5 Simulation des Schaltverhaltens eines SiC-Bipolartransistors . . . . . . . . . . 79 5.5.1 Schaltverhalten bei Ansteuerung mit unipolarem Treiber . . . . . . . . 79 5.5.2 Simulation des Einfluss der Emitter-Induktivität auf Schaltwärme . . . 81 5.5.3 Vergleich von Simulation und Messung . . . . . . . . . . . . . . . . . 82 5.6 Durchlassverlustleistung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6 Einsatz von SiC-Bipolartransistoren im Wechselrichter 6.1 Aufbau der Wechselrichter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 6.2 Inbetriebnahme des Wechselrichters . . . . . . . . . . . . . . . . . . . . . . . 89 6.3 Überspannungen an den Motorklemmen der 1 kW-Asynchronmaschine . . . . 91 6.4 Umbau des SiC-Wechselrichters . . . . . . . . . . . . . . . . . . . . . . . . . 93 6.5 Spannungsspitzen in der Ansteuerspannung . . . . . . . . . . . . . . . . . . . 94 6.6 Halbbrückenverluste im Leerlauf . . . . . . . . . . . . . . . . . . . . . . . . . 98 7 Zusammenfassung und Fazit 101 Literaturverzeichnis 104 A Anhang A.1 Netzliste für SiC-Bipolartransistor FSICBH057A120 . . . . . . . . . . . . . . 113 A.2 Leiterplatten für Doppelpuls-Test und SiC-Wechselrichter . . . . . . . . . . . . 114 A.3 Herleitung des Feldverlaufs in der Driftzone des gesperrten pn-Übergangs . . . 116 A.4 Herleitung des Emitterwirkungsgrads . . . . . . . . . . . . . . . . . . . . . . . 119 A.5 Herleitung des spezifischen Widerstands der Driftzone . . . . . . . . . . . . . 121 A.6 Lebenslauf von Henry Barth . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 A.6.1 Persönliche Angaben . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 A.6.2 Wissenschaftlicher Werdegang . . . . . . . . . . . . . . . . . . . . . . 124 / State-of-the-art are IGBTs and free-wheeling diodes made of silicon (Si). Decades of research have led to an almost perfect technology. Nevertheless, progress in terms of reduction of switching and forward conducting losses becomes smaller and smaller with each new generation of Si IGBTs. The resulting power dissipation, however, can be significantly reduced with power semiconductor devices made of silicon carbide (SiC) and gallium nitride (GaN). The objective of this work is to investigate whether and to what extent discrete SiC bipolar junction transistors (BJT) in TO-247 and SiC Schottky diodes in TO-220 packages can be used to increase the efficiency of a power drive inverter. At the beginning, a digression into silicon carbide semiconductor technology is intended to show its advantages in terms of lower-loss power electronics. The advantages of the semiconductor material silicon carbide are illustrated by the SiC bipolar junction transistor in comparison with the first power transistor - the silicon bipolar junction transistor. For the on-state of SiC bipolar junction transistors, a continuous current must be injected into the base. This increases the driving effort. Therefore, the first topic focuses on the driver. In this work, a simple and a complex driver were built and evaluated. With slight modifications, the more complex driver was also used to drive IGBTs and SiC-MOSFETs for comparative measurements. A new approach to reduce driver power dissipation in the inverter when using SiC bipolar junction transistors is presented. It focuses on the commutation algorithm of the inverter. A significant part of the work is devoted to the characterization of the SiC bipolar junction transistor, especially the switching behavior. Turn-on and turn-off switching losses for different operating points are determined. At the end of the work, experimental investigations are performed on a SiC inverter. Finally, the potentials associated with the use of SiC bipolar junction transistors are evaluated but also the limitations are shown.:1 Einleitung 1 2 Aufbau des SiC-Bipolartransistors 2.1 Siliziumkarbid (SiC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.1 Eigenschaften von monokristallinem Siliziumkarbid . . . . . . . . . . 5 2.1.2 Herstellung des SiC-Wafers . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.3 Herstellung des SiC-Bipolartransistors . . . . . . . . . . . . . . . . . . 10 2.1.4 Defekte im Siliziumkarbidkristall . . . . . . . . . . . . . . . . . . . . 11 2.2 Halbleiterphysikalische Grundlagen . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.1 Gesperrter pn-Übergang . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.2 Stromführender pn-Übergang . . . . . . . . . . . . . . . . . . . . . . . 15 2.3 Bipolartransistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.1 Aufbau und Funktionsprinzip . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.2 Sperrfähigkeit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.3.3 Erster und zweiter Durchbruch . . . . . . . . . . . . . . . . . . . . . . 23 2.3.4 Stromverstärkung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.3.5 Ladungsträgermodulation . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.3.6 Eindimensionaler spezifischer Widerstand der Driftzone . . . . . . . . 30 3 Ansteuerung des SiC-Bipolartransistors 3.1 Einführung Treiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.2 Herausforderungen beim Ansteuern von SiC-Bipolartransistoren . . . . . . . . 34 3.3 Treiberkonzepte für SiC-Bipolartransistoren . . . . . . . . . . . . . . . . . . . 36 3.4 Konventioneller Treiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.5 3-Level-Treiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.6 Treiber für SiC-MOSFET und IGBT . . . . . . . . . . . . . . . . . . . . . . . 45 4 Reduzierung der Treiberverluste durch Einschrittkommutierung 4.1 Einschrittkommutierung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.2 Stromvorzeichenerkennung . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4.3 Berechnung der Verlustleistungen für den eingeschalteten Zustand des SiC- Bipolartransistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.4 Messung der Treiberverlustleistung . . . . . . . . . . . . . . . . . . . . . . . . 52 5 Charakterisierung des SiC-Bipolartransistors 5.1 Messaufbau für Untersuchung des Ein- und Ausschaltverhaltens . . . . . . . . 55 5.2 Doppelpulsverfahren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 5.3 Definition der Schaltzeiten und Schaltverlustleistung . . . . . . . . . . . . . . 57 5.4 Messung der Schaltwärme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.4.1 Spannungstastköpfe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.4.2 Stromsensoren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 5.4.3 Zeitliche Verschiebung der Messsignale . . . . . . . . . . . . . . . . . 62 5.4.4 Vergleich von konventionellem und 3-Level-Treiber . . . . . . . . . . . 65 5.4.5 Vergleich bei unterschiedlicher Treiberspannung . . . . . . . . . . . . 66 5.4.6 Vergleich bei halb und voll bestückter Halbbrücke . . . . . . . . . . . . 68 5.4.7 Vergleich von SiC-Bipolartransistor mit SiC-MOSFET und Si-IGBT . . 69 5.4.8 Reduzierung der Spannungsspitze beim Ausschalten . . . . . . . . . . 74 5.5 Simulation des Schaltverhaltens eines SiC-Bipolartransistors . . . . . . . . . . 79 5.5.1 Schaltverhalten bei Ansteuerung mit unipolarem Treiber . . . . . . . . 79 5.5.2 Simulation des Einfluss der Emitter-Induktivität auf Schaltwärme . . . 81 5.5.3 Vergleich von Simulation und Messung . . . . . . . . . . . . . . . . . 82 5.6 Durchlassverlustleistung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6 Einsatz von SiC-Bipolartransistoren im Wechselrichter 6.1 Aufbau der Wechselrichter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 6.2 Inbetriebnahme des Wechselrichters . . . . . . . . . . . . . . . . . . . . . . . 89 6.3 Überspannungen an den Motorklemmen der 1 kW-Asynchronmaschine . . . . 91 6.4 Umbau des SiC-Wechselrichters . . . . . . . . . . . . . . . . . . . . . . . . . 93 6.5 Spannungsspitzen in der Ansteuerspannung . . . . . . . . . . . . . . . . . . . 94 6.6 Halbbrückenverluste im Leerlauf . . . . . . . . . . . . . . . . . . . . . . . . . 98 7 Zusammenfassung und Fazit 101 Literaturverzeichnis 104 A Anhang A.1 Netzliste für SiC-Bipolartransistor FSICBH057A120 . . . . . . . . . . . . . . 113 A.2 Leiterplatten für Doppelpuls-Test und SiC-Wechselrichter . . . . . . . . . . . . 114 A.3 Herleitung des Feldverlaufs in der Driftzone des gesperrten pn-Übergangs . . . 116 A.4 Herleitung des Emitterwirkungsgrads . . . . . . . . . . . . . . . . . . . . . . . 119 A.5 Herleitung des spezifischen Widerstands der Driftzone . . . . . . . . . . . . . 121 A.6 Lebenslauf von Henry Barth . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 A.6.1 Persönliche Angaben . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 A.6.2 Wissenschaftlicher Werdegang . . . . . . . . . . . . . . . . . . . . . . 124

L'intégration actuelle des systèmes photovoltaïques dans les systèmes d'alimentation conventionnels a montré une croissance importante, ce qui a favorisé l'expansion rapide des micro-réseaux du terme anglais microgrid. Cette intégration a cependant augmenté la complexité du système d'alimentation qui a conduit à de nouveaux défis de recherche. Certains de ces défis de recherche encouragent le développement d'approches de modélisation innovantes en temps réel capables de faire face à cette complexité croissante. Dans ce contexte, une méthodologie innovante est proposée et basée sur les composants pour la modélisation et l'émulation de systèmes photovoltaïques en temps réel integers aux microgrids. L'approche de modélisation proposée peut utiliser le langage de modélisation des systèmes (SysML) pour décrire la structure et le comportement des systèmes photovoltaïques intégrés en tenant compte de leurs caractéristiques multidisciplinaires. De plus, cette étude présente le cadre de spécification de haut niveau des systèmes embarqués (HiLeS) pour transformer les modèles SysML développés en code source destinés à configurer le matériel intégré. Cette caractéristique de la generation automatique de code permet de profiter de dispositifs avec un haut degré d'adaptabilité et de performances de traitement. Cette méthodologie basée sur HiLeS et SysML est axée sur l'étude des systems photovoltaïques partiellement ombragés ainsi que des architectures flexibles en électronique de puissance en raison de leur influence sur les microgrids actuels. En outre, cette perspective de recherche est utilisée pour évaluer les stratégies de contrôle et de supervision dans les conditions normales et de défauts. Ce travail représente la première étape pour développer une approche innovante en temps réel pour modéliser et émuler des systèmes photovoltaïques complexes en tenant compte des propriétés de modularité, de haut degré d'évolutivité et des conditions de travail non uniformes. Les résultats expérimentaux et analytiques valident la méthodologie proposée. / Nowadays, the integration of photovoltaic systems into electrical grids is encouraging the expansion of microgrids. However, this integration has also increased the power system complexity leading to new research challenges. Some of these research challenges require the development of innovative modeling approaches able to deal with this increasing complexity. Therefore, this thesis is intended to contribute with an innovative methodology component-based for modeling and emulating in real-time photovoltaic systems integrated to microgrids. The proposed modeling approach uses the Systems Modeling Language (SysML) to describe the structure and behavior of integrated photovoltaic systems. In addition, this study presents the High Level Specification of Embedded Systems (HiLeS) to transform automatically the developed SysML models in embedded code and Petri nets. These characteristics of automatic code generation and design based on Petri nets allow taking advantage of FPGAs for application of real-time emulation of photovoltaic systems. This dissertation is focused on partially shaded photovoltaic systems and flexible power electronics architectures because of their relevant influence on current microgrids. Furthermore, this research perspective is intended to evaluate control and supervision strategies in normal and fault conditions. This work represents the first step to develop an innovative real-time approach to model and emulate complex photovoltaic systems considering properties of modularity, high degree of scalability, and non-uniform working conditions. Finally, experimental and analytical results validate the proposed methodology.

This dissertation aims at designing a three-phase voltage source inverter based on the SiC devices and mainly the SiC-MOSFET. The designed inverter offers a possibility to drive the power inverter with a very high efficiency, which can reach up to 99% for 16 kW rated power. The design is dedicated to the electric vehicle application, and it aims at • Providing a comparative study on some of the current discrete SiC devices in terms of the total losses and the thermal conductivity. In addition, a behavioral study of the effective channel mobility with temperature variation in the SiC MOSFET will be investigated. • Designing a gate driver which fits with the driving requirements of the SiC-MOSFET and provides a trade-off between the switching losses and the EMI behavior. • Designing a three-phase voltage source inverter with 16 kW rated power; the design includes minimizing the inverter losses and extracts the EMI model of the power inverter by considering the effects of the parasitic parameters; moreover a short guideline for selecting the heat-sink based on the static network is introduced. • Proposing a new and simplified carried-based PWM, this will reduce the harmonics in the output waveforms and enhance the utilization of the DC-link voltage. • Proposing a new strategy for compensating the dead-time effect in carrier based-PWM and to find out the proper dead-time level in VSI based on SiC –MOSFET. • Designing faults diagnosis and protection circuits in order to protect the power inverter from the common faults; overcurrent, short-circuit, overvoltage, and overtemperature faults.

The modulation methods Space Vector PWM (SVPWM), Discontinuous PWM (DPWM1, DPWMMAX) and six-step mode are investigated in the overmodulation range of a voltage-fed induction motor drive. This area enables an increase of inverter output voltage so that drive performance can be enhanced. Though, pulse dropping occurs which results in increased iron losses and current waveform quality degradation. Due to differences in harmonic distortion the modulation methods cause various torque oscillations and power losses in induction motors and inverter drives. To quantify these effects in a squirrel cage induction motor drive a simulation model containing a finite element machine model and an analytic inverter model is developed, in order to find the PWM scheme offering maximum torque and minimal power losses. Additionally, the holistic investigation of machine and inverter losses allows for making statements concerning total losses of drive systems and the most suitable overmodulation scheme for the application.

Solar photovoltaic (PV) parks have proliferated all over the world as a result of the growing demand for electricity, and especially electricity from renewables. As these parks become larger and complex, it becomes increasingly important to develop accurate and efficient mathematical models that can be used to predict their performance and optimize their design. The inverter is an essential component of a solar PV system that converts the DC power generated by the solar panels into AC power that can be used by the grid or by local loads. This research paper presents a comparative study between a pre-existing reference model and a mathematical model, developed specifically for predicting the AC power output of photovoltaic systems. In addition, a hybrid model is included for comparative analysis. The performance of each model was evaluated using real-world data installed at Glava Energy Centre in Hillringsberg, Sweden. The reference and hybrid models showed similar trends in their calculated versus actual values, but the hybrid model outperformed the reference model slightly. The actual power values were found to be similar to the simulated values in all three models. However, the mathematical model was more specific and sensitive to the inverter under consideration, resulting in a comprehensive and accurate representation of the inverter's behaviour. The models take into account the inverter's characteristics, as well as environmental elements like temperature and solar irradiance that affect its performance. The results showed that the mathematical model outperformed the other models in terms of accuracy and reliability, achieving an R2 score of 0.9226, 0.9936, 0.9789, and 0.9736 for the months of February, April, July, and October, respectively. The mathematical model also had the lowest root mean square error (RMSE) and mean absolute error (MAE) values compared to the other models. The results of this study demonstrate the value of mathematical modelling in the design and optimization of solar PV parks and provide a framework for the development of more complex models in the future.