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Fabrique et réversibilité de l’autorité dans l’œuvre de Pierre MichonLeduc-Frenette, Justin 12 1900 (has links)
Le présent mémoire étudie les relations ambivalentes qu’entretient l’œuvre de Pierre Michon avec les positions d’autorité filiale, linguistique, littéraire et historique. Le rapport double – entre destitution et idéalisation de l’autorité – agit comme une matrice symbolique à partir de laquelle l’auteur déploie une série d’oppositions qui régissent ses récits et sa propre fonction auctoriale : le père et le fils, l’illettré et le beau parleur, la gloire et la chute, l’image et l’icône, le corps et la lettre. De ces positions, trois thèmes principaux font saillie : le transfuge culturel, le « grand écrivain » et le tyran révolutionnaire. Ces thématiques fonctionnent sur trois échelles – sociofamiliale, littéraire, politico- historique – qui régissent la structure tripartite du mémoire.
Dans le premier chapitre, j’analyse l’émergence des Vies minuscules (1984), livre de huit hagiographies où le rapport entre l’exiguïté culturelle du milieu d’origine et l’imposture linguistique se pose comme principale tension énonciative. Le deuxième chapitre porte sur la destitution et la glorification de trois figures d’auteurs (Rimbaud, Beckett, Faulkner), par le biais de l’ambivalence structurale du corps faillible, du mythe et de l’iconographie. Le troisième chapitre, sur Les Onze (2009), traite de la fabrique de l’autorité politique dans sa relation avec les structures pulsionnelles et la représentation du pouvoir. Par le passage d’un chapitre à l’autre est ainsi tracé le fil d’Ariane des fictions michoniennes : toute autorité est réversible parce que basée sur une négativité fondamentale qui rend impossible l’appropriation absolue du symbolique. / This thesis examines the ambivalent relationship that Pierre Michon's work maintains with positions of filial, linguistic, literary and historical authority. This twofold relationship - between destitution and idealization of authority - acts as a symbolic matrix from which the author deploys a series of oppositions that govern his narratives and his own auctorial function: father and son, the illiterate and the smooth talker, glory and decline, image and icon, body and letter. From these positions, three main themes protrude: the cultural transfuge, the "great writer" and the revolutionary tyrant. These themes operate on three scales - socio-familial, literary, politico-historical - which govern the tripartite structure of the thesis. In the first chapter, I analyze the emergence of Vies minuscules (1984), a book of eight hagiographies in which the relationship between the cultural exiguity of the native milieu and linguistic imposture is posited as the main enunciative tension. The second chapter focuses on the destitution and glorification of three authorial figures (Rimbaud, Beckett, Faulkner), through the structural ambivalence of the fallible body, myth, and iconography. The third chapter, on Les Onze (2009), deals with the manufacture of political authority in its relation to drive structures and the representation of power. The passage from one chapter to the next thus traces the Ariadne's thread of Michonian fictions: all authority is reversible because it is based on a fundamental negativity that makes absolute appropriation of the symbolic impossible.
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Potenziale bisher vernachlässigter Regionalbahnen am Beispiel der Strecke Dobříš – PrahaEysel, Yannis 30 October 2024 (has links)
Die Diplomarbeit beschäftigt sich exemplarisch mit der Bahnstrecke Dobříš – Praha und untersucht Möglichkeiten, wie diese zukünftig die tschechische Hauptstadt Praha mit der Region südwestlich davon innovativ und kundenorientiert verbinden kann. Dabei erfolgt im ersten Teil der Arbeit eine demografische und verkehrliche Analyse des Untersuchungsgebietes. Diese zeigt, dass durch gezielte Maßnahmen wie der Verbesserung der Zugangsstellen (Bahnhöfe und Haltepunkte) sowie einer Verlängerung der Strecke in die Innenstadt von Dobříš das Fahrgastpotenzial deutlich erhöht werden kann. Anschließend erfolgt eine umfangreiche Recherche zum Thema alternative Antriebe im Schienenverkehr auf Basis verschiedener Studien. Dabei wird der Fokus auf batterieelektrische (BEMU) und wasserstoffbetriebene Lösungen (HEMU) gelegt. Bei dem Vergleich dieser zeigt sich, dass BEMU-Fahrzeuge in der Regel in der Anschaffung und im Betrieb wirtschaftlicher sind als HEMU-Fahrzeuge. Auch bei den Themen Energieeffizienz und CO2-Bilanz schneiden BEMU-Fahrzeuge im Allgemeinen besser ab. Darüber hinaus werden Anforderungen und Anwendungsbeispiele von RegioTram-Systemen sowie deren systembedingte Vorteile und Herausforderungen aufgezeigt. Im letzten Teil der Arbeit werden mögliche Szenarien für eine Anwendung von alternativen Antriebsmöglichkeiten sowie eines RegioTram-Systems auf die zu untersuchende Strecke erarbeitet und auf ökonomischer Bais bewertet. Das Ergebnis zeigt einen klaren Vorteil bei der Nutzung von reinen Oberleitungs- oder BEMU-Fahrzeugen, schließt auch die Einführung einer RegioTram nicht aus und stützt damit die Erkenntnisse aus dem Rechercheteil. Eine quantitative Abschätzung des analysierten Fahrgastpotenzials unterstreicht zudem den Nutzen einer Innenstadtverlängerung in Dobříš. Neben der Zusammenfassung und Diskussion der Ergebnisse werden allgemeine Handlungsempfehlungen für eine Attraktivierung von vernachlässigten Regionalbahnen aufgestellt. / This thesis takes the Dobříš – Praha railway line as an example and examines ways in which it can connect the Czech capital of Prague with the region south-west of it in an innovative and customer-orientated way in the future. The first part of the study analyses the demographics and traffic situation of the examined area. This shows that the passenger potential can be significantly increased through targeted measures such as improving the access points (stations) and extending the line into the city centre of Dobříš. This is followed by extensive research into alternative drive systems in rail transport based on various studies. The focus is placed on battery electric (BEMU) and hydrogen-powered solutions (HEMU). A comparison of these shows that BEMU vehicles are generally more economical to purchase and operate than HEMU vehicles. BEMU vehicles also generally perform better in terms of energy efficiency and carbon footprint. In addition, the requirements and application examples of RegioTram systems as well as their system-related advantages and challenges are shown for a more favourable operation of the examined route. In the final part of the thesis, possible scenarios for the application of alternative drive options and a RegioTram system on the examined route are developed and evaluated on an economic basis. The result shows a clear advantage in the use of pure overhead contact line or BEMU vehicles but does not rule out the introduction of a RegioTram. This supports the findings from the research section. A quantitative estimate of the analysed passenger potential also underlines the benefits of the extension to the city centre in Dobříš. In addition to summarising and discussing the results, general recommendations to make neglected regional railways more attractive are drawn up.
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Alimentation de circuit de commande rapprochée « Gate-drive » pour nouveaux convertisseurs de puissance haute tension / Gate-drive power supply for new high voltage power convertersGhossein, Layal 09 March 2018 (has links)
Le transport d’énergie par des lignes HVDC constitue le principal réseau de transmission d’énergie électrique du futur. Les convertisseurs de puissance (par exemple de type MMC) qui constitueront ce réseau devront être capables de gérer des tensions de l’ordre de centaines de kilovolts ce qui rend critique l’alimentation des dispositifs de contrôle (gate-drive) de ces convertisseurs. Il est nécessaire de concevoir des solutions qui garantissent l’alimentation de ces gate-drives avec une isolation.Pour ce faire, un circuit basé sur le principe du flyback et utilisant un JFET normalement passant a été développé. Il est placé en parallèle d’un condensateur typiquement connecté aux bornes d’un bras d’onduleur. Il permet d’alimenter le dispositif de puissance dès qu’une faible tension est appliquée à son entrée. Cette fonction est assurée grâce au caractère normalement passant du JFET. Pour le prototype développé, la tension du bras est de 2 kV. La tension de sortie est régulée à 24 V. De nos jours, des JFET normalement passants avec une tenue en tension supérieure à 2 kV n’existent pas sur le marché. Donc, pour supporter les tensions mises en jeu dans le circuit, une mise en série de JFET SiC normalement passants commandés par un MOSFET Si a été réalisée (montage « super-cascode »). Le circuit développé est capable de fournir 20 W pour alimenter des gate-drives à des potentiels flottants. Le rendement obtenu est proche de 60 %. Aussi, le problème d’isolation est résolu par cette solution d’auto-alimentation. / HVDC power transmission is the future of the electrical energy transmission network. The power converters (e.g. MMC) used in this network will be able to cope with voltages of hundreds of kV, making the power supply of the gate-drive devices in these converters challenging. It is then necessary to design solutions that guarantee the power supply of these gate-drives, while providing high voltage isolation. To do this, a circuit, based on the flyback principle, was developed. It is placed in parallel with a capacitor typically connected to a half-bridge circuit. It has an auto-start feature. This allows to supply the gate-drive as soon as a low voltage is applied to the input of the self-supply system. This is obtained by taking advantage of the normally-ON character of the JFET. In our prototype, the input voltage is 2 kV. High voltage JFETs of 2 kV and higher breakdown voltages are not yet available on the market. So, to achieve this high voltage capacity, a series of Normally-ON SiC JFETs controlled by a low voltage Si MOSFET (Super-cascode circuit) is used in the circuit. The developed circuit is able to supply 20 W at different floating potentials with output voltage regulated at 24 V and an efficiency close to 60%. The isolation problem is then solved using this solution.
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Forensisk hårddiskkloning och undersökning av hårddiskskrivskydd / Forensic hard disk cloning and investigation of hardware write blockersBengtsson, Johnny January 2004 (has links)
<p>Detta examensarbete reder ut arbetsprinciperna för olika typer av hårddiskskrivskydd; hårdvaruskrivskydd, mjukvaruskrivskydd, hybridskrivskydd och bygelskrivskydd. Slutsatsen av utredningen är att endast hårdvaruskrivskydd Detta examensarbete reder ut arbetsprinciperna för olika typer av hårddiskskrivskydd; hårdvaruskrivskydd, mjukvaruskrivskydd, hybridskrivskydd och bygelskrivskydd. Slutsatsen av utredningen är att endast hårdvaruskrivskydd bedöms ha tillräckligt pålitliga skyddsprinciper, vilket motiveras av dess oberoende från både hårdvara och operativsystem. </p><p>Vidare undersöks hårdvaruskrivskyddet Image MASSter(TM) Drive Lock från Intelligent Computer Solutions (ICS). Några egentliga slutsatser gick inte dra av kretskonstruktionen, bortsett från att den är uppbyggd kring en FPGA (Xilinx Spartan-II, XC2S15) med tillhörande PROM (XC17S15APC). </p><p>En egenutvecklad idé till autenticieringsmetod för hårddiskkloner föreslås som ett tillägg till arbetet. Principen bygger på att komplettera hårddiskklonen med unik information om hårddisk såväl kloningsomständigheter, vilka sammanflätas genom XOR-operation av komponenternas hashsummor.Autenticieringsmetoden kan vid sjösättning möjligen öka rättsäkerheten för både utredarna och den som står misstänkt vid en brottsutredning. </p><p>Arbetet är till stora delar utfört vid och på uppdrag av Statens kriminaltekniska laboratorium (SKL) i Linköping.</p>
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Fast wave heating of cyclotron resonant ions in tokamaksJohnson, Thomas January 2004 (has links)
QC 20100622
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Forensisk hårddiskkloning och undersökning av hårddiskskrivskydd / Forensic hard disk cloning and investigation of hardware write blockersBengtsson, Johnny January 2004 (has links)
Detta examensarbete reder ut arbetsprinciperna för olika typer av hårddiskskrivskydd; hårdvaruskrivskydd, mjukvaruskrivskydd, hybridskrivskydd och bygelskrivskydd. Slutsatsen av utredningen är att endast hårdvaruskrivskydd Detta examensarbete reder ut arbetsprinciperna för olika typer av hårddiskskrivskydd; hårdvaruskrivskydd, mjukvaruskrivskydd, hybridskrivskydd och bygelskrivskydd. Slutsatsen av utredningen är att endast hårdvaruskrivskydd bedöms ha tillräckligt pålitliga skyddsprinciper, vilket motiveras av dess oberoende från både hårdvara och operativsystem. Vidare undersöks hårdvaruskrivskyddet Image MASSter(TM) Drive Lock från Intelligent Computer Solutions (ICS). Några egentliga slutsatser gick inte dra av kretskonstruktionen, bortsett från att den är uppbyggd kring en FPGA (Xilinx Spartan-II, XC2S15) med tillhörande PROM (XC17S15APC). En egenutvecklad idé till autenticieringsmetod för hårddiskkloner föreslås som ett tillägg till arbetet. Principen bygger på att komplettera hårddiskklonen med unik information om hårddisk såväl kloningsomständigheter, vilka sammanflätas genom XOR-operation av komponenternas hashsummor.Autenticieringsmetoden kan vid sjösättning möjligen öka rättsäkerheten för både utredarna och den som står misstänkt vid en brottsutredning. Arbetet är till stora delar utfört vid och på uppdrag av Statens kriminaltekniska laboratorium (SKL) i Linköping.
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Reduced Switch Count Multi-Level Inverter Structures With Common Mode Voltage Elimination And DC-Link Capacitor Voltage Balancing For IM DrivesMondal, Gopal 07 1900 (has links)
Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. Voltage operation above semiconductor device limits, lower common mode voltages, near sinusoidal outputs together with small dv/dt’s, are some of the characteristics that have made this power converters popular for industry and modern research. However, the existing solutions suffer from some inherent drawbacks like common mode voltage problem, DC-link capacitor voltage fluctuation etc. Cascaded multi-level inverter with open-end winding induction motor structure promises significant improvements for high power medium-voltage applications. This dissertation investigates such cascaded multi-level inverters for open-end winding induction motor drive with reduced switch count. Similar to the conventional two-level inverters, other multi-level inverters with PWM control generate alternating common mode voltage (CMV). The alternating common mode voltage coupled through the parasitic capacitors in the machine and results in excessive bearing current and shaft voltage. The unwanted shaft voltage may cross the limit of insulation breakdown voltage and cause motor failure. This alternating common mode voltage adds to the total leakage current through ground conductor and acts as a source of conducted EMI which can interfere with other electronic equipments around.
As the number of level increase in the inverter, different voltage levels are made available by using DC-link capacitor banks, instead of using different isolated power supplies. The intermediate-circuit capacitor voltages which are not directly supplied by the power sources are inherently unstable and require a suitable control method for converter operation, preferably without influence on the load power factor. Apart from normal operation, the sudden fault conditions may occur in the system and it is necessary to implement the control strategy considering this condition also.
A five-level inverter topology with cascaded power circuit structure is proposed in this dissertation with the strategy to eliminate the common mode voltage and also to maintain the balance in the DC-link capacitor voltages. The proposed scheme is based on a dual five-level inverter for open-end winding induction motor. The principle achievement of this work is the reduction of power circuit complexity in the five-level inverter compared to a previously proposed five-level inverter structure for open-end winding IM drive with common mode voltage elimination. The reduction in the number of power switching devices is achieved by sharing the two two-level inverters for both the inverter structures. The resultant inverter structure can produce a nine-level voltage vector structure with the presence of alternating common mode voltage. The inverter structure is formed by cascading conventional two-level inverters together with NPC three-level inverters. Thus it offers modular and simpler power bus structure. As the power circuit is realised by cascading conventional two-level and NPC three-level inverters the number of power diodes requirements also reduced compared to the conventional NPC five-level inverters. The present proposed structure is implemented for the open-end winding induction motor and the power circuit offers more number of switching state redundancies compared to any conventional five-level inverter. The inverter structure required half the DC-link voltage compared to the DC-link voltage required for the conventional five-level inverter structure for induction motor drive and this reduces the voltage stress on the individual power devices. The common mode voltage is eliminated by selecting only the switching states which do not generate any common mode voltage in pole voltages hence there will be no common mode voltage at the motor phase also. The technique of using the switching state selection for the common mode voltage elimination, cancels out the requirement of the filter for the same purpose. As the inverter output is achieved without the presence of common mode voltage, the dual inverter can be fed from the common DC-link sources, without generating any zero sequence current. Hence the proposed dual five-level inverter structure requires only four isolated DC supplies.
The multi-level inverters supplied by single power supply, have inherent unbalance in the DC-link capacitor voltages. This unbalance in the DC-link capacitor voltages causes lower order harmonics at the inverter output, resulting in torque pulsation and increased voltage stress on the power switching devices. A five-level inverter with reduced power circuit complexity is proposed to achieve the dual task of eliminating common mode voltage and DC-link capacitor voltage balancing. The method includes the analysis of current through the DC-link capacitors, depending on the switching state selections. The conditions to maintain all the four DC-link capacitor voltages are analysed. In an ideal condition when there is no fault in the power circuit the balance in the capacitor voltages can be maintained by selecting switching states in consecutive intervals, which have opposite effect on the capacitor voltages. This is called the open loop control of DC-link capacitor voltage balancing, since the capacitor voltages are not sensed during the selection of the switching states. The switching states with zero common mode voltages are selected for the purpose of keeping the capacitor voltages in balanced condition during no fault condition. The use of any extra hardware is avoided. The proposed open loop control of DC-link capacitor voltage balancing is capable of keeping the DC-link capacitor voltages equal in the entire modulation region irrespective of the load powerfactor. The problem with the proposed open loop control strategy is that, it can not take any corrective action if there is any initial unbalance in the capacitor voltages or if any unbalance occurs in the capacitor voltages during operation of the circuit,. To get the corrective action in the capacitor voltages due occurrence of any fault in the circuit, the strategy is further improved and a closed loop control strategy for the DC-link capacitor voltages is established. All the possible fault conditions in the four capacitors are identified and the available switching states are effectively used for the corrective action in each fault condition. The strategy is implemented such a way that the voltage balancing can be achieved without affecting the output fundamental voltage.
The proposed five-level inverter structure presented in this thesis is based on a previous work, where a five-level inverter structure is proposed for the open-end winding induction motor. In that previous work 48 switches are used for the realization of the power circuit. It is observed that all the available switching states in this previous work are not used for any of the performance requirement of CMV elimination or DC-link voltage balancing. So, in this proposed work, the power circuit is optimized by reducing some of the switches, keeping the performance of the inverter same as the power circuit proposed in the previous work. The five-level inverter proposed in this thesis used 36 switches and the number of switching states is also reduced. But, the available switching states are sufficient for the CMV elimination and DC-link capacitor voltage balancing.
The advantage of the modular circuit structure of this proposed five-level inverter is further investigated and the inverter structure is modified to a seven-level inverter structure for the open end winding induction motor. The proposed power circuit of the seven-level inverter uses only 48 switches, which is less compared to any seven-level inverter structure for the open end winding induction motor with common mode voltage elimination. The power circuit is reduced by sharing four two-level inverters to both the individual seven-level inverters in both the sides of the of the open end winding induction motor. The cascaded structure eliminates the necessity of the power diodes as required by the conventional NPC multilevel inverters. The proposed seven-level inverter is capable of producing a thirteen-level voltage vector hexagonal structure with the presence of common mode voltage. The common mode voltage elimination is achieved by selecting only the switching states with zero common mode voltage from both the inverters and the combined inverter structure produce a seven-level voltage vector structure with zero common mode voltage. The switching frequency is also reduced for the seven-level inverter compared to the proposed five-level inverter. The advantage of this kind of power circuit structure is that the number of power diode requirement is same in both five-level and seven-level inverters. Since there is no common mode voltage in the output voltages, the dual seven-level inverter structure can be implemented with the common DC-link voltage sources for both the sides. Six isolated power supplies are sufficient for both the seven-level inverters.
The available switching states in this proposed seven-level inverter are further analysed to implement the open loop and closed loop capacitor voltage balancing and this allow the power circuit to run with only three isolated DC supplies.
All the proposed work presented in this thesis are initially simulated in SIMULINK toolbox and then implemented in a form of laboratory prototype. A 2.5KW open end winding induction motor is used for the implementation of these proposed works. But all these work general in nature and can be implemented for high power drive applications with proper device ratings.
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Multilevel Dodecagonal Space Vector Structures and Modulation Schemes with Hybrid Topologies for Variable Speed AC DrivesKaarthik, R Sudharshan January 2015 (has links) (PDF)
MULTILEVEL inverters are the preferred choice of converters for electronic power conversion for high power applications. They are gaining popularity in variety of industrial applications including electric motor drives, transportation, energy management, transmission and distribution of power. A large portion of energy conversion systems comprises of multilevel inverter fed induction motor drives. The multilevel inverters are ideal for such applications, since the switching frequency of the devices can be kept low. In conventional two level inverters, to get nearly sinusoidal phase current waveform, the switching frequency of the inverter is increased and the harmonics in the currents are pushed higher in the frequency spectrum to reduce the size and cost of the filters. But higher switching frequency has its own drawbacks – in particular for medium voltage, high power applications. They cause large dv_/ dt stresses on the motor terminals and the switching devices, leading to increased electromagnetic interference (EMI) problems and higher switching losses.
Harmonics in the motor currents can further be minimized by adopting dodecagonal voltage space vector (SV) switching (12-sided polygon). In case of dodecagonal SV switching, the fifth and seventh order (6n , 1, n = odd) harmonics are completely eliminated for the full modulation range including over modulation and twelve step operation in the motor phase voltages and currents. In addition to low order harmonic current suppression, the linear modulation range for dodecagonal SV switching is also more by 6% when compared to that of the conventional hexagonal SV switching. The dodecagonal voltage SV structure is made possible by connecting two inverters with DC-link voltages Vd and 0:366Vd on either side of an open-end winding induction motor. The dodecagonal space vector switching can be used to produce better quality phase voltage and current waveforms and overcome the problem of low order fifth and seventh harmonic currents and to improve the range for linear modulation while reducing the switching frequency of the inverters when compared to that of the conventional hexagonal space vector based inverters.
This thesis focuses on three aspects of multilevel dodecagonal space vector structures
(i) Two new power circuit topologies that generate a multilevel dodecagonal voltage space vector structure with symmetric triangles, (ii) A multilevel dodecagonal SV structure with nineteen concentric dodecagons, (iii) Pulse width modulation (PWM) timing calculation methods for a general N-level dodecagonal SV structure.
(i) Two new power circuit topologies capable of generating multilevel dodecagonal voltage space vector structure with symmetric triangles with minimum number of DC link power supplies and floating capacitor H-bridges are proposed. The first power topology is composed of two hybrid cascaded five level inverters connected to either side of an open end winding induction machine. Each inverter consists of a three level neutral point clamped (NPC) inverter, cascaded with an isolated capacitor fed H-bridge making it a five level inverter. The second topology is a hybrid topology for a normal induction motor (star or delta connected), where the power is fed to the motor only from one side. The proposed scheme retains all the advantages of multilevel topologies as well the advantages of the dodecagonal voltage space vector structure. Both topologies have inherent capacitor balancing for floating H-bridges for all modulation indices including transient operations. The proposed topologies do not require any pre-charging circuitry for startup. PWM timing calculation method for space vector modulation is also explored in this chapter. Due to the symmetric arrangement of congruent triangles within the voltage space vector structure, the timing computation requires only the sampled reference values and does not require any iterative searching, off-line computation, look-up tables or angle estimation. Experimental results for steady state operation and transient operation are also presented to validate the proposed concept.
(ii) A multilevel dodecagonal voltage space vector structure with nineteen concentric do-decagons is proposed for the first time. This space vector structure is achieved by connecting two sets of asymmetric hybrid five level inverters on either side of an open-end winding induction motor. The dodecagonal structure is made possible by proper selection of DC-link voltages and switching states of the inverters. In addition to that, a generic and simple method for calculation of PWM timings using only sampled reference values (v and v ) is proposed. This enables the scheme to be used for any closed loop application like vector control. Also, a new switching technique is proposed which ensures minimum switching while eliminating the fifth and seventh order harmonics and suppressing the eleventh and thirteenth harmonics, eliminating the need for bulky filters. The motor phase voltage is a 24-stepped waveform for the entire modulation range thereby reducing the number of switchings of the individual inverter modules. Experimental results for steady state operation, transient operation including start-up have been presented and the results of Fast Fourier Transform (FFT) analysis is also presented for validating the proposed concept.
(iii) A method to obtain PWM timings for a general N-level dodecagonal voltage space vector structure using only sampled reference values is proposed. Typical methods that are used to find PWM timings for dodecagonal SV structures use modulation index and the reference vector angle, to get the timings T1 and T2 using trigonometric calculations. This method requires look-up tables and is difficult to implement in closed loop systems. The proposed method requires only two additions to compute these timings. For multilevel case, typical iterative methods need timing calculations (matrix multiplications) to be performed for each triangle. The proposed method is generic and can be extended to any number of levels with symmetric structures and does not require any iterative searching for locating the triangle in which the tip of the reference vector lies. The algorithm outputs the triangle number and the PWM timing values of T0, T1 and T2 which can be set as the compare values for any carrier based PWM module to obtain space vector PWM like switching sequences. Simulation and experimental results for steady state and transient conditions have been presented to validate the proposed method.
A 3.7 kW, 415 V, 50 Hz, 4-pole open-end winding induction motor was used for the experimental studies. The semiconductor switches that were used to realize the power circuit for the experiment were 75 A, 1200 V insulated-gate bipolar transistor (IGBT) half-bridge modules (SKM75GB12T4). Opto-isolated gate drivers with desaturation protection (M57962L) were used to drive the IGBTs. For the speed control and PWM timing computation a digital signal processor (DSP-TMS320F28335) with a clock frequency of 150 MHz was used. For modulation frequencies 10 Hz and below, a constant sampling frequency of 1 kHz was used as the frequency modulation ratio is high. For modulation frequencies above 10 Hz, synchronous PWM strategy was used. The time duration Ts is the sampling interval for which the timings T1 , T2 and T0 are calculated. As in the case of any synchronous PWM method, the duration of sampling time (Ts) is a function of the fundamental frequency of the modulating signal. In this case, Ts = 1_.fm • 12n) sec. where fm is fundamental frequency in Hertz and ‘n’ is the number of samples per 30ý dodecagonal sector. The PWM timings and the triangle data (from the DSP) is fed to field programmable gate array (FPGA) (SPARTAN XC3S200) clocked at 50 MHz where the actual gating pulses are generated. The capacitor balancing algorithm and the dead-time modules were implemented within FPGA. No external hardware was used for generation of dead-time. The dead-time block generates a constant dead-time of 2 s for all the switches. Extensive testing was done for steady state operations and transient operations including quick acceleration and start-up to validate the proposed concepts.
With the advantages like extension of linear modulation range, elimination of fifth and seventh harmonics in phase voltages and currents for the full modulation range, suppression of eleventh and thirteenth harmonics in phase voltages and currents, reduced device voltage ratings, lesser dv_dt stresses on devices and motor phase windings, lower switching frequency, inherent cascaded H-bridge (CHB) capacitor balancing, the proposed space vector structures, the inverter power circuit topologies, the switching techniques and the PWM timing calculation methods can be considered as viable schemes for medium voltage, high power motor drive applications.
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Elektrický pohon zkušebního pracoviště / Electric drive of testing benchJon, Václav January 2008 (has links)
The master thesis deals with problems of electrical gears divided to the teoretical and practical part of submitted work. Thesis was created in conjuction with company VUES Brno s.r.o. The author of the master thesis accomplished three-month work experience at aforementioned company and consequently solved the national project: Automatic station with utilization of active synchronic brakes for testing electrical hand-held tools. The project included creating full-automatic station for testing life-time cyclic tests electrical hand-held tools. The author of the project engage in programme for frequency transmitter served as headstone of the master thesis.
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Návrh konstrukce zakladače k bezhroté brusce Jupiter 125 / Chalder for grinder Jupiter 125Novák, Aleš January 2008 (has links)
Thesis deal with proposal construction Chalder for centreless grinding machine Jupiter 125. Chalder is designed for workpiece with maximum average 12 mm, maximum longitude 120 mm and mass 0,1 kg. In the thesis are described components that were used at solving and intended time exchanges workpiece, the economics estimation and processed needed design documentation.
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