Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"Thyristors."”.
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Two way power flow using GTO thyristors
Two-way power flow is nothing new and has been in practical use using line commutated converters for at least 50 years. With these types of converters, reversal of power flow can be achieved by increasing the firing angle of the devices beyond 90 degrees thus producing a negative DC voltage. Line …
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Series operation of thyristors in HVDC converters
… in the voltage and current capabilities of thyristors are yielding encouraging results. In contrast to mercuryarc valves, thyristors do not suffer from random phenomena and require minim auxiliaries. Considering these advantages, thyristors offer a viable alternative to mercury arc valves …
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Investigation of MOS-Gated Thyristors and Power Diodes
The MOS-gated thyristors (MGT) refer to the class of power devices that combine the ease of a MOS gate control with the superior current carrying capability of a thyristor structure for high-power applications. The MOS-controlled thyristor (MCT) is a typical MGT device. A comprehensive …
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A study of the turn-on mechanisms in thyristors
… to calculate the initial turned-on area of thyristors.
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The application of thyristors to induction motor drive systems
… of three different power circuit arrangements of thyristors for controlling the speed of an induction motor through control of the stator voltage. The output voltage harmonic structure is provided for each circuit along with a comparison of the motor torque-speed characteristics. Means for coping …
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Modélisation à l'aide du logiciel EMTP-RV du compensateur série variable commandé par thyristors
… Le compensateur série variable commandé par thyristors (CSVCT) est l'un de ces moyens, il permet de compenser un réseau tout en atténuant la résonance sous-synchrone. La chaire TransÉnergie ne possède actuellement pas de modèle permettant la simulation de ce type de compensateur avec EMTP-RV. …
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Optically triggered thyristor for capacitor discharge applications
… of the use of light to trigger semiconductor thyristors for capacitor discharge applications has been conducted. The investigation consisted of a technical literature and background search, design and analysis of optically silicon thyristors, and simulations of a capacitor discharge circuit …
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3-Phase gate-turn off thyristor inverter
… designed, constructed and tested. Gate Turn-Off Thyristors (GTO's) are used as the main switching elements in the Inverter stage of the Drive. The drive requirements of GTO's are studied in detail.
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Feasibility Study of High Current Transistor D.C. Choppers
… choppers.<br/><br/>Present d.c. choppers employ thyristors and are expensive due to the turn-off circuits required. The use of low cost power transistors in electric vehicle chopper controllers is investigated, and a brief survey of power transistors has been carried out to establish which …
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Pulse Density Modulated Soft Switching Cycloconverter
… on combined with the slow switching speeds of thyristors (the switch of choice for standard cycloconverters) limits their use to lower frequency applications. This thesis explores the analysis and design of a pulse density modulated (PDM), soft switching cycloconverter. Unlike standard …
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Control, Topology and Component Investigations for Power-Dense Modular Multilevel Converters
… but partially controlled ones like thyristors. Despite thyristors' historical controllability challenges, incorporating SMs can help resolve control challenges, creating a modular, scalable converter with a wide operation range, high power density, and lower costs. The third avenue …
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The Simulation of a Controlled Tubular Reactor with Counter-current Heat Transfer
… heaters situated in the plant and controlled by thyristors. The control systems investigated were feedback using a conventional controller, feedforward using the analogue computer as on-line controller and combined feedback and feedforward. The comparison between complete simulation and partial …
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MODELLING AND SIMULATION OF A CYCLOCONVERTER INDUCTION MOTOR DRIVE
… the thyristor gate signals used to trigger the thyristors are derived, is based on the traditional cosine timing control technique. This is incorporated in the Simulink model. The resultant behaviour of the machine is obtained by superunposing the effect of the fundamental and harmonics for both …
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Direct digital control of D.C. machines
… thyristor bridge, using phase control of the thyristors, and to use this bridge for the purpose of controlling the speed of a separately excited D. C. machine, under the supervision of a small digital computer. Interfacing equipment for this purpose was designed and built. Various methods of …
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Comprehensive loss optimization of induction motor drives
… gate bipolar transistors and gate commutated thyristors, induction motor drives are increasingly used in applications, ranging from automotive traction to more-electric aircraft, which have widely varying speed, torque and power requirements. Advances in control technology have enabled the …
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A Power Conditioning System for Superconductive Magnetic Energy Storage based on Multi-Level Voltage Source Converter
… of size, speed, and cost. Conventional PCSs use thyristors, due to the power capacity of the SMES system. The speed limit of the thyristor uses a six-pulse operation that generates a high harmonic. To reduce the harmonic, multiple PCSs are connected together with phase-matching transformers that …
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Novel Power Semiconductor Devices and Technologies
… of fast recover diodes, IGBT’s and MOS gated thyristors are also considered. 1200V and 1700V fast recovery diodes are developed employing the same novel p+ offset edge termination technique. The 1200V devices show a hot/cold leakage current and forward voltage drop of 518pA/L42|iA and …
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Electrical, Magnetic, Thermal Modeling and Analysis of a 5000A Solid-State Switch Module and Its Application as a DC Circuit Breaker
… current sharing between paralleled multiple ETO thyristors is investigated. Current sharing is difficult to achieve for a thyristor-type device due to the large device parameter variations and strong positive feedback mechanism in a latched thyristor. The author proposes the "DirectETO" concept …
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The study of the upgrade and improvement of power electronics protection system for locomotives
A dissertation submitted in fulfillment of the requirements for the Master of Engineering Degree in Electrical Power Engineering, Durban University of Technology, Durban, South Africa, 2023.