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Rhéologie des suspensions concentrées de fibres : application à la mise en forme des matériaux composites / Rheology of concentrated fibre suspensions : Application to polymer composite formingGuiraud, Olivier 23 September 2011 (has links)
Cette étude porte sur la mise en forme des matériaux composites renforcés par des fibres ou des mèches de fibres courtes tels que les SMC ou les BMC. Un travail expérimental a dans un premier temps été réalisé à l’échelle macroscopique. Ce travail a permis de mettre au point un rhéomètre de compression lubrifiée ainsi que des méthodes d’essais et de dépouillement. Ceci permet de mieux caractériser la rhéologie des compounds SMC et BMC en traitant les problématiques de leur compressibilité et des frottements éventuels entre les parois du rhéomètre et la matière déformée. Un travail numérique a ensuite permis de simuler la mise en forme d’un BMC après l’identification des paramètres d’un modèle rhéologique simple à partir des données expérimentales obtenues sur le rhéomètre. Enfin, un travail expérimental à l’échelle microscopique a permis d’une part de caractériser finement les microstuctures de SMC modèles à partir de microtomographies à rayons X, et d’autre part de caractériser et de modéliser par le biais d’essais d’extraction de fibres les interactions entre les mèches formant le renfort fibreux de ces matériaux. / This study focuses on the processing of composite materials reinforced with short fibres or fibres bundles such as SMC or BMC. Firstly, an experimental work was carried-out at the macroscopic scale. This work led to the development of a lubricated compression rheometer and associated analysis methods to better characterize the rheology of SMC and BMC compounds, by accounting for the compressibility of compounds and the possible friction between the rheometer wall and the flowing composite. Numerical simulation was then achieved in order to simulate the forming of a BMC. For that purpose, the constitutive parameters of a simple tensorial rheological model were determined from experimental data obtained with the rheometer. Finally, an experimental work at the microscopic level allowed (i) the microstuctures of SMC models from X-ray microtomography micrographs and (ii) fibre pull-out experiment to be characterized, and the interaction mechanisms between the fiber bundles forming the fiber reinforcement of these materials to be modelled.
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Investigations On Small Signal Stability Of Power Systems Affected By FACTS Supplementary Modulation ControllersSaikumar, H V 09 1900 (has links) (PDF)
No description available.
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Sanidic Thermotropic Liquid CrystalsRepasky, Paul J. 29 November 2016 (has links)
No description available.
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Det moderna handledsskyddet för snowboardåkare : en revidering av materialval, funktion och målgruppsanpassningHellström, Kasimir January 2010 (has links)
Projektet behandlar utvecklingen av ett handledsskydd anpassat för snowboardåkare. Den primäramålsättningen är att med hjälp av optimerad design för komfort och användarvänlighet kunnaerbjuda ett högkvalitativt och funktionellt skydd. Det senare uppnås med hjälp av material som medhänsyn till skadebilden hos utövarna här anses vara den bästa lösningen. Val av material gjordes efteren ingående litteraturstudie över handledsskyddets funktion och mekanismerna bakomhandledsskador. Studien, i kombination med en rad andra metoder för informationsinhämtning, lågäven till grund för designprocessen och den slutgiltiga produkten.Lösningar på befintliga problem hos existerande handledsskydd har applicerats på slutprodukten.Användarvänlighet och passform har tillgodosetts genom att frångå det traditionella systemet medkardborrelås, till produktanpassning av ett etablerat snörsystem. En ökad bekvämlighet tillgodosesgenom hela skyddets form, men även med utvalda material, då dessa tillåter luftgenomströmninggenom skyddet.Inom ramen för projektet besvaras också frågeställningar rörande varför så få utövare använderhandledsskydd, och vad som kan göras för att locka till användning. Handledsskydd är idagimpopulära hos utövarna, trots att frakturer på handled är den vanligaste skadan förknippad medsnowboard. Genom utveckling av bättre skydd kan skadestatistiken kraftigt förbättras. / The project aims to develop customized wrist guards for snowboarders. By using optimized design for comfort and ease of use, the primary aim is to offer the customer a functional and high-quality protection. This is achieved by using materials that, considering the injury status of the practitioners, herein are considered to best meet the demands of such a protection. The choice of materials was made after a comprehensive literature-based study on wrist guard function and mechanisms responsible for wrist injuries. This study, along with other collected data, has formed the basis for the design process and the final product. Solutions to current problems with existing wrist guards have been applied to the final product. Requirements on ease of use and accuracy of fit have been met by abandoning the traditional closure-system of Velcro, in favor for an established lacing system that has been adapted to the current product. The entire shape of the wrist guard, combined with the selected materials breathable qualities, offers the user an increased comfort. The complementary aim of the project is to understand why so few practitioners wear wrist guards, and bring forth solutions that attracts to the usage of such. Wrist guards are currently unpopular amongst snowboarders, despite wrist fracture being the most common injury associated with the sport. Through the development of better wrist guards the injury statistics can be greatly improved.
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Modeling and Evaluation of Turret Control Systems for Main Battle TanksLyth, Mikael January 2021 (has links)
The aim of the thesis was to implement and compare control methods in a model of a main battle tank. Three controllers were implemented in a two axis gimbal model and their performances were compared. The comparisons were performed using step changes in the reference signal, frequency analysis of an oscillating reference signal and disturbances, and turret mass uncertainties. The results showed that the sliding mode controller had the best performance for both reference changes and disturbance attenuation. The PID controller had a better performance for the change in reference, compared to the model predictive controller, but a significantly worse disturbance attenuation. Due to model approximations, such as assuming ideal engines and noise reduction, the results likely show a better performance than what can be expected if applied on a real main battle tank. Therefore, the results show an upper limit of the stabilization performance of turret and barrel control and should only be used to compare the controllers. / Målet med uppsatsen var att implementera och jämföra reglermetoder för en teoretisk modell av en modern stridsvagn. Tre metoder implementerades i ett tvåaxligt gimbalsystem och deras prestanda utvärderades. Mer specifikt utvärderades regulatorernas respons för en referensändring, en referensstörning och osäkerheter i tornets massa och massfördelning. Utifrån dessa resultat jämfördes sedan reglermetoderna. Resultaten visade att sliding mode regulatorn hade bäst prestanda för både referensändring och referensstörningen när man tittar på frekvensanalys av mät- och processstörningar. PID-regulatorn hade en bättre prestanda än MPC-regulatorn för en referensändring men en sämre respons för en referensstö-rning. På grund av modellförenklingar som till exempel antaganden om ideala motorer och brusreduktion visar resultaten troligen en något bättre prestanda än vad som kan uppnås på en riktigt stridsvagn. Det medför att resultaten visar en övre gräns för vad styrsystemet för en stridsvagns torn- och eldrörsrotation kan uppnå.
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Estudo comparativo de controladores de estrutura variável por modos deslizantes aplicados a veículos subaquáticos autônomos / Comparative study of variavle structures controllers by sliding modes applied to autonomous underwater vehiclesCildoz, Mariana Uzeda 29 August 2014 (has links)
Made available in DSpace on 2017-07-10T17:11:48Z (GMT). No. of bitstreams: 1
Dissertacao Mariana Uzeda2.pdf: 3273824 bytes, checksum: cb0d125fc8aae9dfe673029b5f5a30a5 (MD5)
Previous issue date: 2014-08-29 / This work presents a comparative study between four different sliding mode variable structure
control strategies (SMVSC) applied to autonomous underwater vehicles (AUV) positioning in
6 DOF, under the influence of wind, waves and marine currents. The addressed strategies are
the conventional CEV-MD control based on Lyapunov stability, the CEV-MD control based on
the equivalent control, the CEV-MD control based on the input-output stability and the CEVMD
adaptive control. The accomplished comparisons seek a satisfactory tradeoff between the
tracking performance and the closed-loop system stability in light of eliminating the chattering
phenomenon. In that sense, the analysis and synthesis of the respective SMVSC control laws is
carried out fromthe Lyapunov Stability Theory and the Barbalat s Lemma. As well as numerical
simulations are implemented to obtaining the respective performances of each SMVSC control
strategy presented. / Este trabalho apresenta um estudo comparativo entre quatro diferentes estratégias de controle
de estrutura variável por modos deslizantes (CEV-MD) aplicadas ao posicionamento de veículos
subaquáticos autônomos (VSA) em 6 GDL, sob a influência de ventos, ondas e correntes
marinhas. As estratégias abordadas são o controle CEV-MD convencional baseado na estabilidade
de Lyapunov, o controle CEV-MD baseado no controle equivalente, o controle CEV-MD
baseado na estabilidade entrada-saída e o controle CEV-MD adaptativo. As comparações realizadas
visam a eliminação do do fenômeno do chattering buscando um compromisso satisfatório
entre o desempenho de rastreamento e a estabilidade do sistema em laço fechado. Nesse sentido,
a análise e síntese das respectivas leis de controle CEV-MD é realizada a partir da Teoria
de Estabilidade de Lyapunov e do Lema de Barbalat. Assim como simulações numéricas são
implementadas para a obtenção dos respectivos desempenhos de cada estratégia de controle
CEV-MD apresentada.
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Residential mortgage loan securitization and the subprime crisis / S. ThomasThomas, Soby January 2010 (has links)
Many analysts believe that problems in the U.S. housing market initiated the 2008–2010 global
financial crisis. In this regard, the subprime mortgage crisis (SMC) shook the foundations of the
financial industry by causing the failure of many iconic Wall Street investment banks and prominent
depository institutions. This crisis stymied credit extension to households and businesses
thus creating credit crunches and, ultimately, a global recession. This thesis specifically discusses
the SMC and its components, causes, consequences and cures in relation to subprime mortgages,
securitization, as well as data. In particular, the SMC has highlighted the fact that risk, credit ratings,
profit and valuation as well as capital regulation are important banking considerations. With
regard to risk, the thesis discusses credit (including counterparty), market (including interest rate,
basis, prepayment, liquidity and price), tranching (including maturity mismatch and synthetic),
operational (including house appraisal, valuation and compensation) and systemic (including maturity
transformation) risks. The thesis introduces the IDIOM hypothesis that postulates that the
SMC was largely caused by the intricacy and design of subprime agents, mortgage origination and
securitization that led to information problems (loss, asymmetry and contagion), valuation opaqueness
and ineffective risk mitigation. It also contains appropriate examples, discussions, timelines
as well as appendices about the main results on the aforementioned topics. Numerous references
point to the material not covered in the thesis, and indicate some avenues for further research.
In the thesis, the primary subprime agents that we consider are house appraisers (HAs), mortgage
brokers (MBs), mortgagors (MRs), servicers (SRs), SOR mortgage insurers (SOMIs), trustees,
underwriters, credit rating agencies (CRAs), credit enhancement providers (CEPs) and monoline
insurers (MLIs). Furthermore, the banks that we study are subprime interbank lenders (SILs),
subprime originators (SORs), subprime dealer banks (SDBs) and their special purpose vehicles
(SPVs) such as Wall Street investment banks and their special structures as well as subprime investing
banks (SIBs). The main components of the SMC are MRs, the housing market, SDBs/hedge
funds/money market funds/SIBs, the economy as well as the government (G) and central banks.
Here, G either plays a regulatory or policymaking role. Most of the aforementioned agents and
banks are assumed to be risk neutral with SOR being the exception since it can be risk (and regret)
averse on occasion. The main aspects of the SMC - subprime mortgages, securitization, as well as
data - that we cover in this thesis and the chapters in which they are found are outlined below.
In Chapter 2, we discuss the dynamics of subprime SORs' risk and profit as well as their valuation
under mortgage origination. In particular, we model subprime mortgages that are able to fully
amortize, voluntarily prepay or default and construct a discrete–time model for SOR risk and profit
incorporating costs of funds and mortgage insurance as well as mortgage losses. In addition, we
show how high loan–to–value ratios due to declining housing prices curtailed the refinancing of
subprime mortgages, while low ratios imply favorable house equity for subprime MRs.
Chapter 3 investigates the securitization of subprime mortgages into structured mortgage products
such as subprime residential mortgage–backed securities (RMBSs) and collateralized debt obligations
(CDOs). In this regard, our discussions focus on information, risk and valuation as well as
the role of capital under RMBSs and RMBS CDOs. Our research supports the view that incentives
to monitor mortgages has been all but removed when changing from a traditional mortgage model to a subprime mortgage model. In the latter context, we provide formulas for IB's profit
and valuation under RMBSs and RMBS CDOs. This is illustrated via several examples. Chapter 3
also explores the relationship between mortgage securitization and capital under Basel regulation
and the SMC. This involves studying bank credit and capital under the Basel II paradigm where
risk–weights vary. Further issues dealt with are the quantity and pricing of RMBSs, RMBS CDOs
as well as capital under Basel regulation. Furthermore, we investigate subprime RMBSs and their
rates with slack and holding constraints. Also, we examine the effect of SMC–induced credit rating
shocks in future periods on subprime RMBSs and RMBS payout rates. A key problem is whether
Basel capital regulation exacerbated the SMC. Very importantly, the thesis answers this question
in the affirmative.
Chapter 4 explores issues related to subprime data. In particular, we present mortgage and securitization
level data and forge connections with the results presented in Chapters 2 and 3.
The work presented in this thesis is based on 2 peer–reviewed chapters in books (see [99] and [104]),
2 peer–reviewed international journal articles (see [48] and [101]), and 2 peer–reviewed conference
proceeding papers (see [102] and [103]). / Thesis (Ph.D. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2011.
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Residential mortgage loan securitization and the subprime crisis / S. ThomasThomas, Soby January 2010 (has links)
Many analysts believe that problems in the U.S. housing market initiated the 2008–2010 global
financial crisis. In this regard, the subprime mortgage crisis (SMC) shook the foundations of the
financial industry by causing the failure of many iconic Wall Street investment banks and prominent
depository institutions. This crisis stymied credit extension to households and businesses
thus creating credit crunches and, ultimately, a global recession. This thesis specifically discusses
the SMC and its components, causes, consequences and cures in relation to subprime mortgages,
securitization, as well as data. In particular, the SMC has highlighted the fact that risk, credit ratings,
profit and valuation as well as capital regulation are important banking considerations. With
regard to risk, the thesis discusses credit (including counterparty), market (including interest rate,
basis, prepayment, liquidity and price), tranching (including maturity mismatch and synthetic),
operational (including house appraisal, valuation and compensation) and systemic (including maturity
transformation) risks. The thesis introduces the IDIOM hypothesis that postulates that the
SMC was largely caused by the intricacy and design of subprime agents, mortgage origination and
securitization that led to information problems (loss, asymmetry and contagion), valuation opaqueness
and ineffective risk mitigation. It also contains appropriate examples, discussions, timelines
as well as appendices about the main results on the aforementioned topics. Numerous references
point to the material not covered in the thesis, and indicate some avenues for further research.
In the thesis, the primary subprime agents that we consider are house appraisers (HAs), mortgage
brokers (MBs), mortgagors (MRs), servicers (SRs), SOR mortgage insurers (SOMIs), trustees,
underwriters, credit rating agencies (CRAs), credit enhancement providers (CEPs) and monoline
insurers (MLIs). Furthermore, the banks that we study are subprime interbank lenders (SILs),
subprime originators (SORs), subprime dealer banks (SDBs) and their special purpose vehicles
(SPVs) such as Wall Street investment banks and their special structures as well as subprime investing
banks (SIBs). The main components of the SMC are MRs, the housing market, SDBs/hedge
funds/money market funds/SIBs, the economy as well as the government (G) and central banks.
Here, G either plays a regulatory or policymaking role. Most of the aforementioned agents and
banks are assumed to be risk neutral with SOR being the exception since it can be risk (and regret)
averse on occasion. The main aspects of the SMC - subprime mortgages, securitization, as well as
data - that we cover in this thesis and the chapters in which they are found are outlined below.
In Chapter 2, we discuss the dynamics of subprime SORs' risk and profit as well as their valuation
under mortgage origination. In particular, we model subprime mortgages that are able to fully
amortize, voluntarily prepay or default and construct a discrete–time model for SOR risk and profit
incorporating costs of funds and mortgage insurance as well as mortgage losses. In addition, we
show how high loan–to–value ratios due to declining housing prices curtailed the refinancing of
subprime mortgages, while low ratios imply favorable house equity for subprime MRs.
Chapter 3 investigates the securitization of subprime mortgages into structured mortgage products
such as subprime residential mortgage–backed securities (RMBSs) and collateralized debt obligations
(CDOs). In this regard, our discussions focus on information, risk and valuation as well as
the role of capital under RMBSs and RMBS CDOs. Our research supports the view that incentives
to monitor mortgages has been all but removed when changing from a traditional mortgage model to a subprime mortgage model. In the latter context, we provide formulas for IB's profit
and valuation under RMBSs and RMBS CDOs. This is illustrated via several examples. Chapter 3
also explores the relationship between mortgage securitization and capital under Basel regulation
and the SMC. This involves studying bank credit and capital under the Basel II paradigm where
risk–weights vary. Further issues dealt with are the quantity and pricing of RMBSs, RMBS CDOs
as well as capital under Basel regulation. Furthermore, we investigate subprime RMBSs and their
rates with slack and holding constraints. Also, we examine the effect of SMC–induced credit rating
shocks in future periods on subprime RMBSs and RMBS payout rates. A key problem is whether
Basel capital regulation exacerbated the SMC. Very importantly, the thesis answers this question
in the affirmative.
Chapter 4 explores issues related to subprime data. In particular, we present mortgage and securitization
level data and forge connections with the results presented in Chapters 2 and 3.
The work presented in this thesis is based on 2 peer–reviewed chapters in books (see [99] and [104]),
2 peer–reviewed international journal articles (see [48] and [101]), and 2 peer–reviewed conference
proceeding papers (see [102] and [103]). / Thesis (Ph.D. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2011.
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Vergleichende Untersuchungen von Mehrpunkt-Schaltungstopologien mit zentralem Gleichspannungszwischenkreis für MittelspannungsanwendungenKrug, Dietmar 16 January 2017 (has links) (PDF)
Die vorliegende Arbeit befasst sich mit einem detaillierten Vergleich von Mehrpunkt-Schaltungstopologien mit zentralem Gleichspannungszwischenkreis für den Einsatz in Mittelspannungsanwendungen. Im Rahmen dieser Untersuchungen wird die 3-Level Neutral Point Clamped Spannungswechselrichter Schaltungstopologie (3L-NPC VSC) sowohl mit Multilevel Flying Capacitor (FLC) als auch mit Multilevel Stacked Multicell (SMC) Schaltungstopologien verglichen, wobei unter Verwendung von aktuell verfügbaren IGBT-Modulen Stromrichterausgangsspannungen von 2.3 kV, 4.16 kV und 6.6 kV betrachtet werden.
Neben der grundlegenden Funktionsweise wird die Auslegung der aktiven Leistungshalbleiter und der passiven Energiespeicher (Zwischenkreiskondensatoren, Flying Capacitors) für die untersuchten Stromrichtertopologien dargestellt. Unter Berücksichtigung verschiedener Modulationsverfahren und Schaltfrequenzen werden Kennwerte für den Oberschwingungsgehalt in der Ausgangsspannung und dem Ausgangsstrom vergleichend evaluiert. Die installierte Schalterleistungen, die Halbleiterausnutzungsfaktoren, die Stromrichterverlustleistungen sowie die Verlustleistungsverteilungen werden für die betrachteten Stromrichtertopologien detailliert gegenübergestellt und bewertet. / The thesis deals with a detailed comparison of voltage source converter topologies with a central dc-link energy storage device for medium voltage applications. The Three-Level Neutral Point Clamped Voltage Source Converter (3L-NPC VSC) is compared with multilevel Flying Capacitor (FLC) and Stacked Multicell (SMC) Voltage Source Converters (VSC) for output voltages of 2.3 kV, 4.16 kV and 6.6 kV by using state-of-the-art 6.5 kV, 3.3 kV, 4.5 kV and 1.7kV IGBTs.
The fundamental functionality of the investigated converter topologies as well as the design of the power semiconductors and of the energy storage devices (Flying Capacitors and Dc-Link capacitors) is described. The installed switch power, converter losses, the semiconductor loss distribution, modulation strategies and the harmonic spectra are compared in detail.
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Vergleichende Untersuchungen von Mehrpunkt-Schaltungstopologien mit zentralem Gleichspannungszwischenkreis für MittelspannungsanwendungenKrug, Dietmar 28 June 2016 (has links)
Die vorliegende Arbeit befasst sich mit einem detaillierten Vergleich von Mehrpunkt-Schaltungstopologien mit zentralem Gleichspannungszwischenkreis für den Einsatz in Mittelspannungsanwendungen. Im Rahmen dieser Untersuchungen wird die 3-Level Neutral Point Clamped Spannungswechselrichter Schaltungstopologie (3L-NPC VSC) sowohl mit Multilevel Flying Capacitor (FLC) als auch mit Multilevel Stacked Multicell (SMC) Schaltungstopologien verglichen, wobei unter Verwendung von aktuell verfügbaren IGBT-Modulen Stromrichterausgangsspannungen von 2.3 kV, 4.16 kV und 6.6 kV betrachtet werden.
Neben der grundlegenden Funktionsweise wird die Auslegung der aktiven Leistungshalbleiter und der passiven Energiespeicher (Zwischenkreiskondensatoren, Flying Capacitors) für die untersuchten Stromrichtertopologien dargestellt. Unter Berücksichtigung verschiedener Modulationsverfahren und Schaltfrequenzen werden Kennwerte für den Oberschwingungsgehalt in der Ausgangsspannung und dem Ausgangsstrom vergleichend evaluiert. Die installierte Schalterleistungen, die Halbleiterausnutzungsfaktoren, die Stromrichterverlustleistungen sowie die Verlustleistungsverteilungen werden für die betrachteten Stromrichtertopologien detailliert gegenübergestellt und bewertet.:Inhaltsverzeichnis
Liste der Variablen i
Liste der Abkürzungen v
1 Einleitung 1
2 Überblick von Mittelspannungsstromrichtertopologien und Leistungshalbleitern 3
2.1 Mittelspannungsumrichtertopologien 3
2.2 Leistungshalbleiter 8
3 Aufbau und Funktion von Mittelspannungsstromrichtertopologien 10
3.1 Neutral Point Clamped Stromrichter (NPC) 10
3.1.1 3-Level Neutral Point Clamped Stromrichter (3L-NPC) 10
3.1.2 Mehrstufige NPC-Umrichter 21
3.2 Flying Capacitor Stromrichter (FLC) 23
3.2.1 3-Level Flying Capacitor Stromrichter (3L-FLC) 23
3.2.2 4-Level Flying Capacitor-Stromrichter (4L-FLC) 33
3.2.3 Mehrstufige Flying Capacitor-Stromrichter (NL-FLC) 39
3.3 Stacked Multicell Stromrichter (SMC) 43
3.3.1 5L-Stacked Multicell Stromrichter (5L-SMC) 43
3.3.2 N-Level Stacked Multicell Umrichter (NL-SMC) 51
4 Modellierung und Auslegung der Stromrichter 59
4.1 Verlustmodell 59
4.1.1 Sperrschichttemperaturen 64
4.2 Auslegung der Leistungshalbleiter 65
4.2.1 Stromauslegung 67
4.2.2 Worst-Case Arbeitspunkte 69
4.3 Auslegung der Zwischenkreiskondensatoren 75
4.3.1 Spannungszwischenkreis 76
4.3.2 Lastseitige Strombelastung und resultierende Spannungswelligkeit im
Spannungszwischenkreis 77
4.3.3 Abhängigkeit der Strombelastung und der Spannungswelligkeit im
Spannungszwischenkreis vom Frequenzverhältnis mf 95
4.3.4 Netzseitige Zwischenkreiseinspeisung 97
4.3.4.1 Zwischenkreiseinspeisung mit idealisiertem Transformatormodell 98
4.3.4.2 Zwischenkreiseinspeisung mit erweitertem Transformatormodell 101
4.3.5 Simulation des Gesamtsystems 104
4.4 Auslegung der Flying Capacitors 107
4.4.1 Strombelastung der Flying Capacitors 109
4.4.2 Spannungswelligkeit über den Flying Capacitors 113
4.4.3 Abhängigkeit der Spannungswelligkeit der Flying Capacitors vom
Frequenzverhältnis mf 124
4.4.4 Auswirkung der Spannungswelligkeit der Flying Capacitors auf die
Ausgangsspannungen 126
5 Vergleich der Stromrichtertopologien 129
5.1 Daten für den Stromrichtervergleich 129
5.2 Basis des Vergleiches 132
5.3 Vergleich für einen 2,3 kV Mittelspannungsstromrichter 134
5.3.1 Vergleich bei verschiedenen Schaltfrequenzen 134
5.3.2 Vergleich bei maximaler Trägerfrequenz 142
5.4 Vergleich für einen 4,16 kV Mittelspannungsstromrichter 146
5.4.1 Vergleich bei verschiedenen Schaltfrequenzen 146
5.4.2 Vergleich bei maximaler Trägerfrequenz 153
5.5 Vergleich für einen 6,6 kV Mittelspannungsstromrichter 156
5.5.1 Vergleich bei verschiedenen Schaltfrequenzen 156
5.5.2 Vergleich bei maximaler Trägerfrequenz 162
5.6 Vergleich von 2,3 kV, 4,16 kV und 6,6 kV Mittelspannungsstromrichtern 165
5.6.1 Vergleich bei identischer installierter Schalterleistung SS 165
5.6.2 Vergleich bei einer identischen Ausgangsleistung 167
6 Zusammenfassung und Bewertung 171
Anhang 175
A. Halbleiterverlustmodell 175
Referenzen 177 / The thesis deals with a detailed comparison of voltage source converter topologies with a central dc-link energy storage device for medium voltage applications. The Three-Level Neutral Point Clamped Voltage Source Converter (3L-NPC VSC) is compared with multilevel Flying Capacitor (FLC) and Stacked Multicell (SMC) Voltage Source Converters (VSC) for output voltages of 2.3 kV, 4.16 kV and 6.6 kV by using state-of-the-art 6.5 kV, 3.3 kV, 4.5 kV and 1.7kV IGBTs.
The fundamental functionality of the investigated converter topologies as well as the design of the power semiconductors and of the energy storage devices (Flying Capacitors and Dc-Link capacitors) is described. The installed switch power, converter losses, the semiconductor loss distribution, modulation strategies and the harmonic spectra are compared in detail.:Inhaltsverzeichnis
Liste der Variablen i
Liste der Abkürzungen v
1 Einleitung 1
2 Überblick von Mittelspannungsstromrichtertopologien und Leistungshalbleitern 3
2.1 Mittelspannungsumrichtertopologien 3
2.2 Leistungshalbleiter 8
3 Aufbau und Funktion von Mittelspannungsstromrichtertopologien 10
3.1 Neutral Point Clamped Stromrichter (NPC) 10
3.1.1 3-Level Neutral Point Clamped Stromrichter (3L-NPC) 10
3.1.2 Mehrstufige NPC-Umrichter 21
3.2 Flying Capacitor Stromrichter (FLC) 23
3.2.1 3-Level Flying Capacitor Stromrichter (3L-FLC) 23
3.2.2 4-Level Flying Capacitor-Stromrichter (4L-FLC) 33
3.2.3 Mehrstufige Flying Capacitor-Stromrichter (NL-FLC) 39
3.3 Stacked Multicell Stromrichter (SMC) 43
3.3.1 5L-Stacked Multicell Stromrichter (5L-SMC) 43
3.3.2 N-Level Stacked Multicell Umrichter (NL-SMC) 51
4 Modellierung und Auslegung der Stromrichter 59
4.1 Verlustmodell 59
4.1.1 Sperrschichttemperaturen 64
4.2 Auslegung der Leistungshalbleiter 65
4.2.1 Stromauslegung 67
4.2.2 Worst-Case Arbeitspunkte 69
4.3 Auslegung der Zwischenkreiskondensatoren 75
4.3.1 Spannungszwischenkreis 76
4.3.2 Lastseitige Strombelastung und resultierende Spannungswelligkeit im
Spannungszwischenkreis 77
4.3.3 Abhängigkeit der Strombelastung und der Spannungswelligkeit im
Spannungszwischenkreis vom Frequenzverhältnis mf 95
4.3.4 Netzseitige Zwischenkreiseinspeisung 97
4.3.4.1 Zwischenkreiseinspeisung mit idealisiertem Transformatormodell 98
4.3.4.2 Zwischenkreiseinspeisung mit erweitertem Transformatormodell 101
4.3.5 Simulation des Gesamtsystems 104
4.4 Auslegung der Flying Capacitors 107
4.4.1 Strombelastung der Flying Capacitors 109
4.4.2 Spannungswelligkeit über den Flying Capacitors 113
4.4.3 Abhängigkeit der Spannungswelligkeit der Flying Capacitors vom
Frequenzverhältnis mf 124
4.4.4 Auswirkung der Spannungswelligkeit der Flying Capacitors auf die
Ausgangsspannungen 126
5 Vergleich der Stromrichtertopologien 129
5.1 Daten für den Stromrichtervergleich 129
5.2 Basis des Vergleiches 132
5.3 Vergleich für einen 2,3 kV Mittelspannungsstromrichter 134
5.3.1 Vergleich bei verschiedenen Schaltfrequenzen 134
5.3.2 Vergleich bei maximaler Trägerfrequenz 142
5.4 Vergleich für einen 4,16 kV Mittelspannungsstromrichter 146
5.4.1 Vergleich bei verschiedenen Schaltfrequenzen 146
5.4.2 Vergleich bei maximaler Trägerfrequenz 153
5.5 Vergleich für einen 6,6 kV Mittelspannungsstromrichter 156
5.5.1 Vergleich bei verschiedenen Schaltfrequenzen 156
5.5.2 Vergleich bei maximaler Trägerfrequenz 162
5.6 Vergleich von 2,3 kV, 4,16 kV und 6,6 kV Mittelspannungsstromrichtern 165
5.6.1 Vergleich bei identischer installierter Schalterleistung SS 165
5.6.2 Vergleich bei einer identischen Ausgangsleistung 167
6 Zusammenfassung und Bewertung 171
Anhang 175
A. Halbleiterverlustmodell 175
Referenzen 177
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