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El presente trabajo de final de grado tiene como objetivo ofrecer una propuesta de un cargador de pared bidireccional para el uso en redes residenciales mediante la definición de las especificaciones técnicas, para dar respuesta a la potencial necesidad de gestión de la energía en este entorno, añadiendo la posibilidad de integrar la batería del vehículo eléctrico en la vivienda. Es necesario destacar que en el alcance de este proyecto no se considera el desarrollo del hardware ni del software del producto, ni la fabricación de ningún prototipo. La carga bidireccional es la carga de los vehículos eléctricos que funciona en ambos sentidos: extrayendo energía de la red para cargar la batería del vehículo y suministrando electricidad desde la batería del vehículo. Un vehículo eléctrico puede alimentar un hogar, una empresa, la red eléctrica, otro vehículo o cargas específicas. Esta tecnología nos abre una nueva puerta al uso del vehículo eléctrico. Para el desarrollo del proyecto se analizará el estado del arte en cuestión, centrado en los cargadores del mercado actual, los vehículos y la tecnología. Posteriormente, y una vez estudiada la normativa principal que ha de cumplir esta solución, se analizará la necesidad de mercado para el 2025-2030, centrada en cuatro puntos, el usuario, el operador, los vehículos y por último las instalaciones domésticas. Estos estudios abrirán la puerta a distintas posibles soluciones, empezando por un usuario que será recurrente en un futuro a esta tecnología con la necesidad de la gestión de la energía de su hogar, punto en el cual el operador puede entrar en juego, aunque en España no sea habitual tener a un operador para gestionar un punto de recarga doméstico, si lo es en otros países de la Unión europea, y esto puede ser una realidad de cara al año 2030. Por otro lado, tendremos los vehículos eléctricos, donde se plantea la cuestión de si van a permitir la carga bidireccional, y a través de corriente continua o de corriente alterna. Y finalmente se definen 3 posibles situaciones de instalaciones domésticas que vamos a encontrar en un futuro. Con esta información se procederá a definir los requisitos funcionales que esta solución debe cumplir, y posteriormente a realizar la especificación técnica de la propuesta de solución final, que permita solucionar todas las necesidades encontradas anteriormente, centrados en el HW y el SW necesario. Finalmente, con este proyecto, se ha podido llegar a la conclusión que dentro del caso hipotético, de tener VE que permitan la carga bidireccional en DC, debido principalmente a la poca eficiencia que tiene el realizarlo en AC, y teniendo unas instalaciones domésticas con un bus de continua que puedan integrar paneles solares, el cargador e incluso baterías externas, esta solución de recarga bidireccional, cumple con el objetivo principal de flexibilizar la gestión de la energía en un entorno doméstico, y puede ser una realidad muy habitual en pocos años.

This paper proposes a cascaded single phase multilevel inverter using an off-the-shelf three-phase inverter and transformer. The concept is based on a cascaded connection of two inverter legs using a typical three phase inverter in such a way that the third leg is shared between the other two phases. The cascaded connection is achieved through an integrated series transformer with a typical three-phase transformer core. Utilization of a special transformer design has been previously proposed in the Custom Power Active Transformer. However, cascaded connection of inverter legs has not been previously investigated with such a concept. In this way, a three-leg inverter and a three-phase transformer are converted into an isolated multilevel single-phase inverter based on an unique configuration and modulation technique.

El present projecte es basa en l’estudi dels interruptors industrials. Per a entendre què els caracteritza i per a què serveixen, primer de tot s’han d’estudiar i entendre els fenòmens elèctrics contra els quals actuen. És per això que estudiar els interruptors industrials requereix un pas previ en el que s’estudiïn els defectes dels circuits elèctrics. Posteriorment, aquest projecte estudia les característiques generals dels dispositius de protecció elèctrica englobats dintre els interruptors industrials, ja que és l’associació de diferents dispositius de protecció la que conforma les característiques, funcionalitats i aplicacions dels interruptors industrials. Seguidament, aquest projecte presentarà diferents aparells de protecció elèctrica que conformen la família dels interruptors automàtics, explicant les seves característiques, els dispositius que els conformen i per a què s’utilitzen, ja que cadascun té el seu àmbit d’aplicació. Després de la part teòrica dedicada a entendre els dispositius de protecció i els defectes contra els que actuen es passarà a oferir un conjunt d’exemples reals de com aquests dispositius es poden coordinar, coordinació explicada a la part teòrica. Finalment es mostrarà un cas pràctic en el que s’utilitzarà un software de càlcul de corrents de curtcircuit i es compararà amb els valors obtinguts analíticament per a comprovar la seva validesa.

During the last years, Resistive Random-Access Memories (ReRAMs or RRAMs) stimulated growing attention as promising non-volatile (NV) candidate memories to surpass existing storage devices while exhibiting excellent performance, reliability and low-energy operation and in the same time be utilized for unconventional computing paradigms such as neuromorphic and in-memory computation. In this paper, a brief review on the current state of the art for RRAMs is provided mainly focusing on the resistance switching mechanisms for various materials and corresponding devices. More specifically, we report on the switching mechanisms of RRAMs considering resistance bi-stability due to phase transformation, interfacial resistive switching, conductive filaments and thermochemical effects while the effect of environmental conditions like moisture and temperature is also analyzed. Finally, preliminary results related to our on-going investigations on such a type of Metal-Insulator-Metal (MIM) RRAMs devices derived from Silicon Nitride and compatible with existing CMOS technology are presented and further discussed.

The three-level neutral-point-clamped (3L-NPC) topology is competitive in the large wind energy conversion systems (WECS) thanks to its simple implementation and proper performance compared to other topologies. However, the 3L-NPC topology does not allow distributing power losses evenly among the switching devices, which limits its output power capability. Current literature focuses on the three-level active neutral-point-clamped (3L-ANPC) as an evolution of the 3L-NPC, enabling a more even power loss distribution. However, some devices still suffer from significant switching and conduction power losses with typical commutation sequences. This paper proposes a novel commutation sequence for a 3L-ANPC inverter leg to force that each device mainly withstands either switching or conduction losses. This enables the selection of optimum devices for each position, resulting in an improved converter loss distribution, thermal performance, efficiency, and output power capability. A 2 MW low-voltage WECS is simulated with an electro-thermal model developed in PLECS, reaching a reduction of around 16% in total switching losses. In addition, an enhanced thermal performance is achieved, reducing the maximum junction temperature increase above ambient temperature, on average for all devices, around 4%. The thermal advantages are considerably higher in certain devices, reaching maximum reductions of around 17% in the maximum junction temperature increase above ambient temperature and about 40% in the maximum device junction temperature variation. All reductions are with reference to the conventional commutation sequence.

Resumen: A partir de un modelo teórico se estudia el comportamiento del devanado de un transformador con el objetivo de encontrar la distribución de sobretensiones a lo largo del mismo y así establecer posibles puntos de falla en presencia de transitorios provocados por la onda PWM producida por los variadores de velocidad en instalaciones de extracción de petroleo. En este estudio se incluyen los componentes de la instalación eléctrica de extracción de petroleo como por ejemplo, los conductores primario y secundario del transformador; el motor de la bomba eléctrica sumergible, el variador de velocidad con salida tipo PWM y por supuesto el transformador. Al detectar puntos del devanado del transformador vulnerables a falla, será posible acondicionar la construcción del aislamiento de los devanados para mitigar los efectos de estas sobretensiones. Maestría

El presente trabajo estudia el problema de restablecimiento del servicio de energía eléctrica después de un evento que genera la interrupción del servicio. Se formula un modelo matemático que entrega un grupo de posibles soluciones para restablecer un circuito de distribución, afectado por un evento dado. Este problema se aborda con el fin de proporcionarle al operador del centro de control una herramienta que le ayude a gestionar el evento. Para este trabajo se opta por utilizar una herramienta madura y muy utilizada para la automatización en todo el sector industrial, las Redes de Petri Coloreadas, las cuales facilitan representar problemas de sistemas de eventos discretos y dinámicos. En este sentido se plantea un modelo matemático basado en Redes de Petri que permita ejecutar tres procesos, ubicación de la falla, aislamiento de la zona fallada y restablecimiento del servicio a las zonas “sanas”. Aunque en la literatura se encuentra mucha información y estudios alrededor del tema, se resalta que este trabajo combina las tres etapas del proceso, localización, aislamiento y restablecimiento, teniendo en cuenta aspectos y restricciones relevantes para el Operador de Red (OR), que reflejan los lineamientos operativos y experiencia de los operadores de un centro de control. Entre los aspectos más relevantes se destacan la operación de equipos locales y remotos conjuntamente, así como la verificación de disponibilidad de las comunicaciones. Dadas las características intrínsecas del problema y su naturaleza combinatoria, el modelo busca optimizar la solución mediante una función objetivo y sus restricciones asociadas. La Metodología planteada se evalúa y prueba con un circuito de distribución perteneciente al Sistema de Distribución Local (SDL) de Empresas Públicas de Medellín. En las pruebas se contrasta las soluciones propuestas por el algoritmo con las decisiones tomadas por un operador en una situación real. Los resultados fueron satisfactorios evidenciando el cumplimiento de los criterios establecidos. Abstract: This paper studies the problem of restoring the electric service after been affected by a given event. Hence it is proposed mathematical model that yields a set of possible solutions for service restoration on the distribution grid. This issue is addressed in order to provide the control center operator a tool to help them manage the grid event optimally. The underline technology for this work is a mature concept and widely adopted for automation throughout the industrial sector, Coloured Petri Net (CPN). CPN facilitates problems been represented by discrete systems and dynamic events. This mathematical model based on CPN is capable of implementing three processes, fault location, isolation and service restoration to the "healthy" areas. Although there is several information and studies around this topic, this work combines the three stages or processes: location, isolation and restoration, taking into account relevant aspects and constraint established for System Operator. This reflects the operational guidelines and experience of the operators. Among the most relevant aspects are highlighted the remote and local operation of grid devices in addition with checking communications availability. Given the intrinsic characteristics of the problem and its combinatorial nature, this model looks for optimize the solution through an objective function and its associated restrictions. The proposed methodology is evaluated and tested with a distribution circuit belonging to the Local Distribution System (SDL) of Empresas Públicas de Medellín. The test contrasted the solutions proposed by the algorithm with the decisions taken by the operator on a given real situation. The result was very satisfactory fulfilling the requirements Maestría

Um dos mais importantes elementos que compõem uma rede de telecomunicações é o roteador. Os roteadores modernos empregam sofisticados comutadores para a transmissão de pacotes. A arquitetura de comutadores com filas de entrada exige um processo de escalonamento que estabelece a transferência de pacotes das portas de entrada às portas de saída. O desempenho do sistema depende diretamente do algoritmo de escalonamento, considerando sua vazão e complexidade. Esta dissertação realiza o levantamento teórico dos algoritmos de escalonamento mais relevantes e propõe uma abordagem de escalonamento usando algoritmos genéticos. Um simulador baseado em eventos discretos foi desenvolvido para a realização de testes de desempenho dos escalonadores estudados. O algoritmo proposto, denominado GENIUS, apresentou desempenho relevante e baixa complexidade. One of the most important components of network telecommunications is the router. Modern routers employ input-queued crossbar switches that require sophisticated scheduling techniques for packet transmission. The architecture of switches with input queues requires an scheduling process that establishes the transfer of packets from input to output ports. The performance of router depends of the scheduling algorithm, considering its throughput and complexity. In this work we survey the most relevant theoretical scheduling algorithms and propose a scheduling approach using genetic algorithms. We developed a simulator of discrete events for testing of schedulers performance. The proposed algorithm, called GENIUS, presents relevant performance and low complexity.

Multi level inverter technology has overcome the common three level inverters, as for the better output and performance, one of the most common use of the inverter is to produce pure sine wave from dc supply however this paper present Multi level inverter to be used as harmonic source, this paper will discuss the Inverter configuration to produce 9 levels output (typical) or can be boosted to produce 11 or 13 with using 2 extra switches. This paper discusses the switching strategy to control the inverter, and calculate the switching angles for the required output signal.

n flying capacitor (FC) converters, phase-shifted pulse-width modulation (PS-PWM) provides natural voltage balancing. However, for a practical application, a more robust balancing mechanism of maintaining the FC voltages at the desired values is required. This paper proposes a new closed-loop voltage balancing method for multilevel FC converters using PS-PWM. The proposed method balances the voltages of the FCs by modifying the duty cycle of each switch of the FC converter using a proportional (P) controller. The crossed effect between FC currents and duty cycles is considered and is used for FC voltage balancing. The Simulation results verify that the proposed voltage balancing method is very robust to different operating conditions, such as load transients and non-linear loads.

The teaching of Power Electronics at university Level can be simplified and can be more effective by employing the Switching Function Technique. A unified approach to the operation and analysis of any power converter circuit is possible. The authors tried this approach for a number of years at the Cyprus University of Technology and at Brunel University. This teaching approach is based on the identification of the appropriate switching function which can be applied to a power converter. The switching function is a series of pulses of unity magnitude and it is expressed as a series of sinusoids and its parameters are the ON period of the pulses as well as their phase angles. Analytical expressions of current and voltage waveforms are derived at any point of the circuit -preferably the input and output- as a series of sinusoids. This makes the identification of the order of the harmonics straightforward and the calculation of harmonic magnitude & phase, THD, PF etc. possible.

In flying capacitor (FC) converters, phase-shifted pulse-width modulation (PS-PWM) provides natural voltage balancing. However, for a practical application, a more robust balancing mechanism of maintaining the FC voltages at the desired values is required. This paper proposes a new closed-loop voltage balancing method for multilevel FC converters using PS-PWM. The proposed method balances the voltages of the FCs by modifying the duty cycle of each switch of the FC converter using a proportional (P) controller. The crossed effect between FC currents and duty cycles is considered and is used for FC voltage balancing. The Simulation results verify that the proposed voltage balancing method is very robust to different operating conditions, such as load transients and non-linear loads.

Ultra-high-frequency signals are generated due to particle movement, floating conductors, corona, and surface discharges in gas-insulated switchgear. The ultra-high-frequency signal generated due to particle movement is independent of operating pressure and applied voltage. The bandwidth of the ultra-high-frequency signal formed due to corona and surface discharges vary with applied voltage. In a ternary plot, each type of discharge has a unique location. If a variety of discharge occurs simultaneously, it is difficult to classify the type of discharges through the ternary plot. It is demonstrated that the type of discharge can be classified efficiently by adopting a multi-class support vector machine. � 2011 Copyright Taylor and Francis Group, LLC.

A continuació es detallen els objectius concrets del present treball. -Explicar breument els antecedents històrics de la font commutada i el concepte de correcció del factor de potència. Intentar comprendre perquè a l’actualitat es fa servir la tipologia Boost per a aquest tipus de fonts, així com perquè s’utilitza l’estratègia de control OCC (control en un cicle) enlloc d’altres, i quin camí s’ha anat seguint al llarg de la història tecnològica fins a arribar a l’estat de l’art actual. -Fixar unes especificacions concretes per a la font a dissenyar, dins dels mínims que exigeix el Departament, personalitzat en aquest cas en el tutor del projecte. Aquestes especificacions han de ser realistes amb la tecnologia emprada, i podran estar sotmeses a actualitzacions durant la fase de disseny, atenent a les disponibilitats de components al mercat. En aquest punt val a ressaltar el fet que, donada la naturalesa del projecte que ens ocupa, un dels objectius del qual és posar a prova el mòdul que proporciona el Departament, i del qual no es coneix el comportament que tindrà en un sistema complet complex, l’enumeració d’especificacions tindrà un fort component enumeratiu i de màxims. Es reitera, doncs, que es serà molt flexible quant a aquestes al llarg de l’elaboració del projecte. -Realitzar un càlcul detallat dels valors nominals per als components dels diferents subcircuits que integren la font, entorn del mòdul de potència aportat pel Departament. Els resultats d’aquest disseny es comparen amb els proporcionats per les eines de disseny i simulació que proporciona el fabricant del circuit de control que ve integrat al mòdul, International Rectifier. No només es calcularan valors elèctrics nominals; l’estudi previ també servirà per decidir altres paràmetres, com toleràncies i aspectes tèrmics i mecànics. -Dissenyar el circuit imprès que implementi la font d’alimentació calculada, recolzant-nos en eines de CAD electrònic. Generar a partir d’aquest la documentació necessària per a la fabricació de la placa, que anirà a càrrec del Departament. -Coordinar la fabricació de la placa de circuit imprès i la compra dels components necessaris als proveïdors escollits. -Realitzar el muntatge de components al circuit imprès prototipus, així com l’assemblatge mecànic de la mateixa amb el radiador i els components mecànics necessaris.-Posar en marxa el circuit prototipus, validar el seu funcionament, fent-hi els ajustaments que siguin necessaris i, si es dóna el cas, modificar-ne el disseny per a complir les especificacions fixades. -Prendre mesures del comportament elèctric i funcional del prototipus, que documentin el funcionament de la font i el compliment de les especificacions. -Realitzar la documentació tècnica que reflexi el disseny, muntatge i validació de la font commutada, i que serà la base del text d’aquest projecte de final de carrera. -Extreure de l’estudi sobre el circuit dissenyat, conclusions raonades i documentades sobre el mòdul de potència que integra

This paper is a postprint of a paper submitted to and accepted for publication in IET Power Electronics and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library. The aim of this study is to present a set of closed-form analytical equations in order to enable the computation of the three-phase bridge rectifier steady-state performance estimation. The proposed method presented in this study is a fast, accurate and effective mathematical model for analysing three-phase full-wave controlled rectifiers. The steady-state mathematical model is based on the derivation of an appropriate set of switching functions using the general switching matrix circuit (GSMC) techniques. Once the switching functions are derived, the output current, input current and output dc voltage can all be easily derived and generated from the application of this technique. The effect of overlap is accurately modelled and the distortion (notches), frequency content on the input (voltage and current) and output voltage distortion are derived. The proposed mathematical model, unlike conventional analytical methods, can be integrated in the design of active filters. Furthermore, the output voltage reduction, the rms, average and peak values of voltages and currents for the thyristors and any other semiconductor devices used are readily available for the designer by direct substitution into closed-form equations without any need for the waste of time for worst-case scenario simulations. This method can also be applied to other types of converters, specifically to all voltage fed power converters.

El present projecte final de carrera s'emmarca dins de l’àmbit de dispositius semiconductors de potència emprats com a interruptors. El camp d’aplicació dels interruptors semiconductors de potència és ampli, sent-ne un exemple el condicionament d’energia elèctrica. L’objectiu principal del projecte és l'obtenció d’un circuit muntat sobre una placa de circuit imprès per provar interruptors semiconductors controlats per tensió. El circuit permet obtenir les característiques de conducció i commutació dels dispositius que s’analitzen. El projecte es pot desglossar en dues fases, una fase de disseny del circuit i una fase d’execució o muntatge. Durant la fase de disseny s’ha utilitzat el programari Orcad 10.5 com a suport informàtic. Un objectiu secundari, que deriva de la construcció d’un circuit, és la verificació que el seu funcionament és correcte. Amb aquesta finalitat s’han determinat les característiques de commutació d’un parell d'interruptors (per a unes condicions de contorn concretes), atenent a les dades aportades pel fabricant del dispositiu. S'han dissenyat experiments específics per a les parts del circuit que no poden ser degudament analitzades amb l'obtenció de les característiques de commutació d'un dispositiu.

The force acting on a current carrying body, which is induced by magnetic fields gained more interest due to new applications. These magnetic techniques are used for decades to accelerate or move objects, for instance for catheter navigation in the human body, metal forming or for fast opening of electrical circuit breakers. Due to the increase in short circuit power in most grid systems, and thereby larger prospective currents, conventional AC and DC switches lose interest. This has led to an increased interest in faster and hybrid switching techniques. For this reason a novel electro-mechanical set-up has been developed, which accelerates a movable electrical contact extremely fast by using the combination of Lenz law and the Lorentz force. This contribution describes the mixed domain simulation environment and the validation of the set-up, which consist of a linear electro-magnetic drive and a mechanical damper system. The prototype used for validation is capable to generate a maximum driving force of approximately 200 kN, which accelerates the movable contact of 2.7 kg to 18 m s-1. Initial simulations have been compared with the measurements and the results are in good agreement. This tool can be used to develop generic hybrid circuit breakers, reduces the risk for switchgear manufacturers and speed up the introduction of hybrid switch systems, which is urgently needed due to the ever increase of short circuit power in grid systems and the introduction of DC grid systems.

The force acting on a current carrying body, which is induced by magnetic fields gained more interest due to new applications. These magnetic techniques are used for decades to accelerate or move objects, for instance for catheter navigation in the human body, metal forming or for fast opening of electrical circuit breakers. Due to the increase in short circuit power in most grid systems, and thereby larger prospective currents, conventional AC and DC switches lose interest. This has led to an increased interest in faster and hybrid switching techniques. For this reason a novel electro-mechanical set-up has been developed, which accelerates a movable electrical contact extremely fast by using the combination of Lenz law and the Lorentz force. This contribution describes the mixed domain simulation environment and the validation of the set-up, which consist of a linear electro-magnetic drive and a mechanical damper system. The prototype used for validation is capable to generate a maximum driving force of approximately 200 kN, which accelerates the movable contact of 2.7 kg to 18 m s-1. Initial simulations have been compared with the measurements and the results are in good agreement. This tool can be used to develop generic hybrid circuit breakers, reduces the risk for switchgear manufacturers and speed up the introduction of hybrid switch systems, which is urgently needed due to the ever increase of short circuit power in grid systems and the introduction of DC grid systems.

This research investigates the distortion on the electrical distribution system for a high voltage DC Integrated Power System (IPS). The analysis was concentrated on the power supplied to a propulsion motor driven by an inverter with simulated silicon carbide switches. Theoretically, silicon carbide switches have the advantage of being able to withstand a very large blocking voltage and carry very large forward currents. Silicon carbide switches are also very efficient due to their quick rise and fall times. Since silicon carbide switches can withstand high voltage differentials and switch faster than silicon switches, the switching effects on the electrical distribution system were investigated. The current state of silicon carbide power electronics was also investigated. This research quantifies the current and voltage distortion over various operating conditions. A system model was developed using Matlab, Simulink, and SimPowerSystems. The model consisted of a synchronous generator supplying a rectifier and inverter set driving an induction motor. This induction motor simulates the propulsion motor for a Navy ship. This model had a DC link voltage of 10 kV in order to simulate future Navy IPS systems. The current and voltage distortion were compared to MIL STD 1399 and IEEE STD 519 and 45. http://archive.org/details/analysisofsystem109453006 Contract Number: N62271-97-G-0026 Approved for public release; distribution is unlimited.

L’objectiu principal d’aquest projecte ha consistit en el disseny, implementació i estudi d’un control de tipus distribuït basat en l’anomenat mètode de caiguda per controlar equips modulars de potència en paral•lel. Cada mòdul consta d’una etapa de potència consistent en un convertidor reductor de tensió DC-DC de tipus buck implementat a partir del commutador integrat LM2575. Cada mòdul consta també d’una etapa de control basada en el control de tipus distribuït anomenat mètode de caiguda. El sistema ha estat implementat i s’ha verificat amb un estudi al laboratori el seu funcionament mitjançant diverses proves per obtenir les dades necessàries i comprovar la seva resposta.

The energy output of a magnetic flux compression generator (MFCG) is fed into the vircator load to generate high power microwave through the pulsed power conditioning system, which has adopted the exploding wires as a opening switches. To find out the governing mechanisms on the behavior of the fuse opening switches, the optimal circuit parameters for maximum efficiency subject to compactness, experimental and theoretical approaches has been conducted. Physical transformation occurring during the explosion of the wires are divided in two processes such that A) Heating processes: [ 1) Heating to the melfing process, 2) Melting, 3) Heating of the fluid metal in the linear regime, 4) Further heating to the boiling point and beyond, and 5)Onset of the vaporization wave.] B) Heating-Cooling processes: [1) Transit of the wave and core heating, and 2) Current interruption (plausible) and C) Cooling processes: [1) vapor expansion, 2)) Thermal wave propagation, and 2) Shock wave propagation]. The nonideal plasma produced in the expanding exploding wire column are analyzed over the very wide ranges of plasma parameter such as temperature and density. For the weakly and moderate plasmas the Coulomb logarithm has been modified and extended its applicability in the Spitzer conductivity based on the binary collision models. In the early stages the plasma states have been described using density function theory and the various conductivity models, including Ziman theory and incipient Rydberg state model, have been adopted with modification as wide-range versions. Stressing on the resistance variation after onset of explosions as Shockwaves and/or thermal waves propagate the obtained resistance data as a function of wire parameters and energy injected can be used to investigate the interaction with the vircator load, which can be represented as various equivalent circuit possibly assumed for emulating the impedance characteristics of a nonlinear component.

This thesis details the design, construction, and preliminary testing of a Neutral Point Clamped Power Inverter. The inverter is designed for the 100 kilowatt class of inverters and has a three phase output connection and a neutral connection. The inverter is designed around insulated gate bipolar transistor as the power switching devices. The inverter employs software generation of the gate signals for the power switches and gate driver electronics to ensure reliability and insulation between the high power and low power circuitry. The inverter produces a true three level line-to-neutral voltage waveform and a true five level line-to-line voltage waveform. The true descriptor indicates that a zero voltage output is not produced by averaging two potentials. Rather, a zero voltage output is produced by connecting the output voltage to a neutral point. To date, the inverter has been tested at 20 kilowatts of continuous power.

Generally, the limiting component in a pulsed power system is the switch This is due to the fact at some point, the switch transfers all of the energy in the system High voltage and current create a rough environment for switch electrodes and insulators. In previous studies of switch reliability and lifetime, electrode erosion has received much attention. This investigation deals with the mechanisms behind electrode fracture, which presents an immediate problem, rather than erosion, which has long-term effects on switch performance. The switches under study are spark gaps with graphite electrodes. The spark gap closes when an electric arc forms between the electrodes, and current conduction begins Strong mechanical forces are generated as the arc forms and impact the electrodes. The purpose of this research is to determine the dominant pressure mechanism of electrode fracture, and the propagation of the pressure wavefront through the electrode. Energy is stored in a 5 kJ, 60 kV capacitor, and shorted through the spark gap. This is done to duplicate prior experimental work at Physics International Company. Operating parameters, such as gap spacing, air pressure, charging voltage, inductance, and magnetic pulse shaping, are varied, and mechanical pressure is measured using a strain gage mounted on a ceramic bar. Experimental data from the strain gage is compared to theoretical modeling done in Mathcad and PSPICE.

Switch level faults, as opposed to traditional gate level faults, can more accurately model physical faults found in an integrated circuit. However, existing fault simulation techniques have a worst-case computational complexity of O(n²), where n is the number of devices in the circuit. This paper presents a novel switch level extension to parallel fault simulation and the switch level circuit partitioning needed for parallel processing. The parallel switch level fault simulation technique uses 9-valued logic, N and P-type switch state tables, and a minimum operation in order to simulate all faults in parallel for one switch. The circuit partitioning method uses reverse level ordering, grouping, and subgrouping in order to partition transistors for parallel processing. This paper also presents an algorithm and complexity measure for parallel fault simulation as extended to the switch level. For the algorithm, the switch level fault simulation complexity is reduced to O(L²), where L is the number of levels of switches encountered when traversing from the output to the input. The complexity of the proposed algorithm is much less than that for traditional fault simulation techniques. Ph. D.

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A system designed to investigate the performance of dielectrics in a multichannel surface discharge switch was built and tested. The apparatus consisted of a constant current charging supply that produced 10 mA at 50 kV, a storage capacitor, a 6-ohm stripline, the surface switch, a matched 5-ohra copper sulfate water load, and diagnostics. Diagnostics to evaluate the dielectric performance included capacitive voltage probes in the stripline, a video camera to record multichannel events on videocassettes, and an optically isolated counter to record the number of events in a test run. Typical operating parameters were: 180 joules per pulse, a peak voltage of 40-50 kV, and a peak current of 7 kA. Dielectric samples were tested by placing them in the switch for 19,000 shots at a repetition rate of 1-1.2 pulses per second. The dielectrics were then compared by observing their erosion, changes in breakdown voltage, and the number of channels that occur during discharges. Further analysis to study possible chemical change in the surfaces of three of the dielectrics was performed using Electron Spectroscopy for Chemical Analysis (ESCA).

For an opening switch an attaching gas must be used to obtain a fast opening time in a diffuse discharge. In the process of optimizing gas mixtures in an electron beam sustained discharge, three different types of gas mixtures are presented. The first type of gas mixture utilizes one attaching gas, C2F6, Ternary gas mixtures, utilize two attaching gases, C2F6 and CF4, and are used in the optimization process for repetitive switching in an inductive energy storage system. The last type of gas mixture contains argon as a buffer gas with the Penning admixture C2H2, which increases the ionization efficiency of the gas mixture. Recommendations are made for a repetitive switch for inductive energy storage, a closing switch, and an opening switch.

The effects of fluid velocity and electrode divergence angle on the performance of a gas-blown spark gap switch operating in a self-breakdown mode are presented. The switch was contained in a two-dimensional, axially blown, diverging wind tunnel with an aspect ratio of 40:1. The mean gap velocities, the mean flow velocities in the plane of the minimum separation point, ranged from 4 to 17 m/s. The divergence angles studied were 5.0, 7.5, and 10.0 degrees. The flushing gas used was instrument grade dry air ( < 10 ppm H20 ), and the electrode material was 304 stainless steel. High-speed interferograms were used to verify the data reduction program and to identify all events. The relationship between the minimum mean gap velocity, Ūth, and divergence angle, 0, required for a predetermined failure rate was determined in this study. This relationship is of the form, Ūth = A*e-(b0)+B, which illustrates the importance of the divergence angle on the flow rate required for successful switch operation.

The effects of mass flow rate and electrode divergence angle on the performance of a gas-blown spark gap switch operated in the self-breakdown repetitive mode are presented. The switch was flushed with a two-dimensional, laminar flow directed between a diverging pair of electrodes. Voltage versus t i a e data were obtained for two average flow velocities, based on the flow area at the point of minimum electrode separation, of 4.1 and 8.2 m/s. The two divergence angles used were 5 and 10 degrees, and the minimum electrode separation distance was 2.54 ma. High-speed interferograms showing density variations in the gas were obtained and linked with the voltage data in order to identify various types of breakdown events and to develop both qualitative and quantitative definitions for use in the reduction of the data. From the analysis of the data, it was determined that an increase in either the mass flow rate or the electrode divergence angle improved switch performance by reducing the percentage of switch closures which were considered failures.

Insulator materials that are used in surface discharge switches or rail accelerators are subjected to the intense heat and chemistry of the arc plasma and must maintain their mechanical and electrical properties in order for the device to be dependable. The selection criteria for insulators used in these applications are presented. These criteria reflect an expected level of insulator performance and their usefulness in the selection of candidate insulator materials is determined by comparing the expected and the experimental performances of a given group of ceramic insulators. They are shown to be inadequate means of predicting the performance of the ceramic insulators considered here. The ceramics that were chosen include A12O3—SiC (alumina with 25% silicon carbide whisker reinforcement), CZA 500 (alumina and zirconia composite), MTF (aluminum titanate), Si3N4 (silicon nitride), TTZ (zirconia stabilized with magnesium oxide), and ZDY (zirconia stabilized with yttrium oxide). These materials were tested in a surface discharge switch (-300 kA, 20 fis pulse) using atmospheric air and nitrogen as discharge gases. EDX (Energy Dispersive X-ray) surface analysis is performed on the A12O3O-3—SiC, CZA 500, and MTF to determine the surface contaminants present and the possible failure modes that are caused by such contaminants. The temperature increase on the insulator's surface is assumed proportional to the I R heating in the arc discharge, and the temperature scaling, as a function of the arc current and arc resistance, is discussed. Methods to improve insulator performance in high current arc environments are also discussed.

During the last several years, interest In high voltage switches for pulsed power applications has increased significantly. One main concern in the field of pulsed power Is that of energy storage. While inductive energy storage systems have space and weight savings when compared with capacitive energy storage systems, they also require the use of a high power opening switch. Therefore, opening switch technology has started to be developed, and several concepts for opening switches are currently being studied. One particular concept is that of the diffuse discharge opening switch, which has several advantages over other types of opening switches. A significant advantage of the diffuse discharge opening switch is that it may be externally controlled by optical means or by an electron beam. In this paper, three experiments are presented which study the use of optically enhanced attachment as a discharge control mechanism in diffuse discharges. The first experiment demonstrates the effect of UV enhanced attachment in an externally sustained discharge. The second experiment shows the effect of IR illumination in a self sustained discharge. The last experiment demonstrates the effect of IR enhanced attachment in an externally sustained discharge. Future experiments in optically enhanced attachment are also discussed.

Switching regulators are modeled as an unterminated two-port circuit to provide flexibility in system model building. Each functional block of switching regulators is modeled as an independent module so that an arbitrary regulator can be configured. Unified models for large-signal and small-signal analysis are developed in user-friendly manner. Analysis capabilities of switching regulator model are demonstrated using EASYS software program. M.S.

A new microprocessor based synchronous switch has been developed at Virginia Tech as an improvement on the customary solid state electronic or mechanical switch. The author designed and built a 16-pole synchronous switch using a 16 bit microprocessor to provide programmable control on both the opening and closing times for each of the 16 poles of the switch. The user can define a sequence of states (short circuit and open circuit) for each of the 16-poles with control on a) The instant of shorting. b) The instant of opening. The above single shot action can be made repetitive by defining a period of repetition. The device is particularly useful in power system projects and has a unique place in repetitive and 'one time' switching in power system models. The switch is totally self-contained and can be operated through a terminal interfaced to an 8086 microprocessor based microcomputer. The microcomputer was developed and is dedicated to this application alone. The use of 8086 microprocessor facilitates realization of a relatively trouble free, noiseless operation. The system design contains a zero-crossing detector circuit which is used to interrupt the microcomputer for synchronisation. The system has buffered output ports which are connected to mercury wetted relays. These relays are controlled for ON and OFF operation by the user through the above system. The smallest short circuit duration of the order of 2 to 3 msecs can be achieved as determined by the mercury wetted relays. The switch can be used for any purpose where it is desired to accurately control switching points (opening, closing or faulting) on any low power AC network. The switch can be quite useful in studying transient phenomena on three-phase system models. The switch is useful in studying responses of various relaying schemes where it is desirable to test the relay at precise switching angles. Additionally, the switch would be very useful to test or operate circuit breaker models in the power simulation laboratory. M.S.

Diffuse discharges containing electronegative gases, at present, are the only means capable of fast, repetitive, long-life operation as opening switches. Optical control of diffuse discharge switches has been proposed as both a means of sustaining and of enhancing the performance of such switches. Processes considered in this dissertation are photo ionization. photo detachment. and several approaches to optically enhanced attachment. Ultraviolet (UV) ionization has been used for several years now as a means of preionizing self-sustained diffuse discharges and, recently, has been used as a sustainment mechanism for diffuse discharge opening switches. Time-resolved measurements of the optical emission of a spark array, similar to those used for preionization or sustainment of diffuse discharges, are presented. Results of experiments in atmospheric pressure diffuse discharges containing admixtures of attachers, sustained and initiated by such a spark array, are also presented. Photo detachment is considered as a mechanism which could decrease switch losses and decrease switch closure time by counteracting dissociative attachment. Experimental results are presented demonstrating optically increased current densities, of as much as 900%, in externally sustained and externally initiated, atmospheric pressure, diffuse discharges containing 0^. This process proceeds through photodetachment of 0 by 590 nm light generated by a dye laser (0 +hu -• 0+e). Optically enhanced attachment through the generation of vibrationally excited attachers appears particularly attractive as a means to decrease turn-off or opening times for diffuse discharge switches. For some molecules attachment cross-sections can be increased by orders of magnitude by vibrational excitation. The influence of this effect on the resistivity of a discharge through IR pumping of NH.;^ and CpH^aF by a low power CO^ laser in continuous low pressure discharges is presented. UV enhanced attachment is also shown in gases containing molecules such as C^HpF^. CpHpClp, and CpH-Cl where UV photo dissociation produced vibrationally excited, strongly attaching, molecules (e.g.. C2H2F2+hu-C2H2+HF(v>1)).

An investigation of laser triggered switching using a 1.06 µ NdrYAG laser to trigger a uniform field gap filled with 800 Torr of N2 has been performed in the following triggering geometries: 1) Transverse not striking electrodes, 2) Coaxial not striking electrodes, 3) Coaxial striking target electrode, and 4) Coaxial striking recess in target electrode. Streak photography, time resolved spectroscopy, and current measurements reveal great differences in the breakdown processes for the various geometries. The major differences are attributable to laser field interaction with the incipient arc channel. All breakdown processes except types 2 and 3 look quite similar to an overvolted breakdown. Diagnostics of type 2 triggering have shown a laser assisted streamer propagating from the laser fireball to the opposite electrode. Streak photography shows the streamer precursor of the breakdown channel initially proceeds across the gap at a few times 10 cm/sec, but slows to about 2X10 cm/sec as it advances in the focal cone to regions of lower laser intensity. The laser interaction with the streamer produces a uniform, high conductivity channel which emits intense continuum light once ohmic heating raises the channel temperature. When delay is greater than the laser pulse length two distinct regions can be detected in the arc channel; one, laser assisted, showing the abrupt, uniform continuum luminosity, and the other not laser assisted, appearing much like a weakly overvolted breakdown process, exhibiting a glow discharge stage followed by thermalization proceeding from the ends of the glow region towards the middle at 10 cm/sec.

Necesidades tecnológicas en la docencia universitaria requieren un sistema para proporcionar electricidad a partir de enchufes en los escritorios del alumnado. Este sistema debe proporcionar una gran movilidad de las mesas para que puedan colocarse según los requerimientos de cada clase. También se deben facilitar las tareas de mantenimiento y limpieza, y evitar el cableado por el suelo para mejorar la accesibilidad a las aulas con silla de ruedas. El sistema consistirá en la alimentación de pequeñas redes de mesas interconectadas entre sí y situadas según la conveniencia de la clase. Las mesas de cada red se proporcionarán electricidad las unas a las otras a partir de una única toma de corriente situada en la pared. Además, el diseño de la mesa tendrá en cuenta los problemas generados por los campos electromagnéticos del cableado. Esto será posible en gran parte por el sistema de descarga electrostática mediante de las propias patas, evitando así el síndrome de lipoatrofia semicircular y pudiéndose aplicar a la gran mayoría de mesas y escritorios con esta misma problemática. En este proyecto, se demuestra la viabilidad de fabricación de este producto mediante el diseño de esta mesa a partir de componentes disponibles en el mercado y componentes fabricados a medida. También se demuestra la viabilidad económica del proyecto, consiguiendo un precio competitivo para una mesa con grandes valores añadidos comparándola con el resto del mercado.

The flying capacitor (FC) multilevel converter requires a capacitor voltage balancing mechanism for proper operation. This paper proposes a voltage balancing scheme for a five-level FC converter based on phase disposition pulse-width modulation (PD-PWM) using transitions that produce the minimum number of switching events. This strategy will be called optimal-transition voltage balancing (OTVB) scheme. Since multiple optimum switching transitions between two consecutive voltage levels may be available, such a redundancy is used to regulate the FC voltages at their desired levels. Those transitions that produce more switching events are avoided. The rest of transitions are evaluated by means of a cost function and the one that produces the minimum value is selected. Simulation results show a significant reduction of the average switching frequency as compared to the use of the optimal-state voltage balancing (OSVB) scheme, while maintaining the balance of the FC voltages. Moreover, the proposed PD-PWM voltage balancing strategy is robust to static and dynamic load conditions.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This paper proposes a new device by combining features of an interline dual H-bridge current flow controller with the core idea of a hybrid HVdc circuit breaker for meshed HVdc grid application. The proposed device can substitute two dc circuit breakers at a dc bus with at least two adjacent transmission lines. In addition to the current interruption action, the current in one of the adjacent lines can be controlled by the embedded current flow controller. The system-level behavior of the proposed current flow controlling hybrid dc circuit breaker is similar to that of the typical hybrid dc circuit breaker and the interline dual H-bridge current flow controller. The operation principles of the proposed device are introduced and analyzed in this work. The component ratings are compared to the existing solution, and the functionality of the proposed device is verified by simulation.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works The conventional design of voltage-source power converters is based on a two-level half-bridge configuration and the selection of power devices designed to meet the full application specifications (voltage, current, etc.). This leads to the need to design and optimize a large number of different devices and their ancillary circuitry and prevents taking advantage from scale economies. This paper proposes a paradigm shift in the design of power converters through the use of a novel configurable device consisting on a matrix arrangement of highly-optimized switching cells at a single voltage class. Each switching cell consists of a controlled switch with antiparallel diode together with a self-powered gate driver. By properly interconnecting the switching cells, the switching cell array (SCA) can be configured as a multilevel active-clamped leg with different number of levels. Thus, the SCA presents adjustable voltage and current ratings, according to the selected configuration. For maximum compactness, the SCA can be conceived to be only configurable by the device manufacturer upon the customer needs. For minimum cost, it can also be conceived to be configurable by the customer, leading to field-configurable SCAs. Experimental results of a 6x3 field-configurable SCA are provided to illustrate and validate this design approach.