Dissertations / Theses on the topic 'Active compensation'
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Müller, Jonas [Verfasser]. "Active Toe-Angle Compensation / Jonas Müller." München : Verlag Dr. Hut, 2013. http://d-nb.info/1035049937/34.
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Bush, Robert Walton. "Design of an active acceleration compensation robot." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19314.
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Anwar, Saeed. "Active Power Compensation of Microgrid Connected Systems." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1406653103.
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Carpenter, Paul Andrew. "Active filter current compensation for transmission optimisation." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24291.
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This dissertation is based on the fact that any m-wire electrical system can be modelled as m-equivalent Thevenin voltages and impedances when viewed from any node. The dissertation describes how to calculate the optimal distribution of currents, so a specific amount of power can flow through and reach the network equivalent Thevenin voltages with minimal losses. The optimal current distribution method uses a recently patented method which calculates the optimal currents for each of the wires which are shown to be obtained from the Thevenin parameters and power flow at any instant in time at any node. Once the ideal currents are found, these can be obtained by active and passive devices to inject a specific amount of power (positive and negative) as to compensate existing currents. The focus is particularly on the proof of concept by simulations and physical experiments with work not specifically described in the patent with more emphasis on the optimisation to active compensation. It is explained and shown how this can be implemented using the Malengret and Gaunt method. This method reduces the cost in application where not all the currents need to be processed through a converter (e.g. inverter) but only the difference between the existing and desired optimal currents. A smaller shunt parallel converter can result with ideal current flow without the need for interrupting the currents as described in the present patent. The methodology is explained and demonstrated by simulation.
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Decker, Michael Wilhelm. "Active acceleration compensation for transport of delicate objects." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21258.
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Pinfold, W. R. "An active motion compensation system using multiple bodies." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381330.
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Pomierski, Wojciech. "Position signal filtering for hydraulic active heave compensation system." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71095.
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In the paper a new position signal filtering method with position prediction is presented along with test results using a simulation tool. The complete active heave compensation system performance with input signal filtering is also shown. The control system uses an input acceleration signal taken from the motion reference unit, which usually contains noise that is not acceptable for the position controller. Currently, a Kalman filter is used which is okay to use for certain conditions. The filter works similarly to how it is used for autonomous applications where two input positions are necessary, one from position sensors and another one taken from the model. The challenge is that there is no physical wave model available for the Kalman filter used for offshore position control and the waves are not predictable. It was found that a Kalman filter with a special signal prediction instead of the model input can be used. This position prediction helps to avoid system delays and the potential of missing the signal for a short period of the time.
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Granjon, Pierre. "Contribution à la compensation active des vibrations des machines électriques." Phd thesis, Grenoble INPG, 2000. http://tel.archives-ouvertes.fr/tel-00101286.
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Ce travail de recherche est consacré à l'élaboration d'une méthode de compensation active des vibrations d'une machine tournante électrique. Son originalité tient au fait que les enroulements statoriques sont alimentés pardes courants de commande additionnels afin d'engendrer des forces radiales sur le stator. Celui-ci répond alors par des vibrations additionnelles qui interagissent avec les vibrations naturelles de la machine. Le but de ce
système de contrôle actif est donc de calculer la valeur ”optimale” de ces courants, permettant de minimiser la puissance des signaux vibratoires au niveau de capteurs accéléromètriques fixés à la périphérie du stator.
Dans un premier temps, la modélisation du transfert situé entre les commandes et les contre-vibrations engendrées conduit à un système linéaire et variant périodiquement dans le temps (LVPT). La fréquence fondamentale de ses variations est alors proportionnelle à la fréquence de rotation de la machine.
Après avoir montré l'insuffisance des méthodes classiques de contrôle actif pour cette application, une étude théorique détaillée des systèmes LVPT est réalisée. Elle conduit à la définition d'une matrice de transfert, jouant le même rôle que la fonction de transfert classique employée pour les systèmes linéaires et invariants dans le temps. Cette matrice permet d'écrire simplement la relation entre les entrées et les sorties du système
considéré dans le domaine fréquentiel.
Finalement, les résultats précédents sont utilisés afin de déterminer l'expression optimale des courants de commande minimisant la puissance des signaux de vibrations mesurés. Un algorithme récursif permet également de converger vers cet optimum, et de prendre en compte d'éventuelles variations des perturbations vibratoires à éliminer. Divers résultats, obtenus sur des signaux synthétiques puis sur des signaux vibratoires réels, illustrent les performances obtenues par ce système de contrôle actif. Il permet une réduction significative des vibrations
synchrones au phénomène de rotation, sans pour autant modifier les caractéristiques des autres. Enfin, son implantation en temps-réel dans un processeur numérique de traitement de signal est discutée et réalisée.
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Argillander, Joakim. "Active Phase Compensation in a Fiber-Optical Mach-Zehnder Interferometer." Thesis, Linköpings universitet, Informationskodning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166419.
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This thesis investigates the phenomena of phase stability in a fiber-optical MZI (Mach-Zehnder Interferometer). The MZI is a key building block of optical systems for use in experiments with both continuous-wave light and with single photons. By splitting incoming light into two beams and allowing it to interfere with itself, an interference pattern is visible at the output, and this phenomena can be used to code information. This is the operating principle in, for example, QKD (Quantum Key Distribution) experiments. This interference requires coherence that is higher than the length difference between the beams that the incoming light is split into. Particularly the phase of the beams must be equal to achieve constructive interference. If one beam is phase-shifted (with respect to the other) due to the light having traversed a longer path, only partially constructive interference is achieved. If the phase shift also varies with time this leads to a system where experiments can no longer reliably be performed. Sources of these fluctuations are thermal, acoustic or mechanical. Fiber-optical interferometers are particularly sensitive to path length fluctuations of the waveguides as the fiber-optic medium contracts and elongates with temperature, and also has a larger surface area for circulating air to mechanically disturb the waveguides than bulk optics interferometers. In this thesis, a solution to environment-induced phase drift is presented by evaluating implementations of feedback algorithms for automatic control. The algorithms PID (Proportional-, Integral-, Derivative controller) and an ICA (IncrementalControl Algorithm) have been investigated and the performance of these controllers has been compared when used with, and without, optical enclosures. The algorithms are implemented in an FPGA (Field-Programmable Gate Array) and the controller actuates an electro-optical phase modulator that can add a phase shift to one of the light beams in the MZI. This thesis shows that significant improvement in the optical stability can be achieved with active control compared to an interferometer without active phase control.Det här examensarbetet undersöker fenomenet fasstabilitet i en fiber-optisk MZI (Mach-Zehnder-Interferometer). MZI:n är en viktig byggsten i optiska system som används till experiment med både kontinuerligt emitterande lasrar och med enskilda fotoner. Genom att dela upp inkommande ljus i två strålar och låta det interferera med sig själv så bildas ett interferensmöster vid utgången vilket kan användas för att koda information. Det här är huvudprincipen bakom, till exempel, experiment inom QKD (kvantnyckeldistribution, eng: Quantum Key Distribution). Denna interferens förutsätter en koherens (högre än längdskillnaden mellan strålarna) mellan strålarna som det inkommande ljuset är uppdelat i. Särskilt måste fasen hos de bägge strålarna vara lika för att åstadkomma fullständig konstruktiv intereferens. Om en stråle är fasförskjuten (i förhållande till den andra) på grund av att ljuset har färdats en längre sträcka så uppnås endast delvis konstruktiv interferens. Om fasförskjutningen även varierar med tiden så leder det till ett system där experiment inte längre kan pålitligt utföras. Sådana fluktuationer är orsakade av termiskt, akustiskt samt mekaniskt varierande effekter. Fiberoptiska interferometrar är särskilt känsliga mot förändringar i vågledarnas längd. Detta på grund av att det fiberoptiska mediet dras ihop respektive sträcks ut med temperaturen, samt att fibern har en större ytarea som cirkulerande luft kan påverka mekaniskt jämfört med interferometrar konstruerade av bulkoptik. I det här examensarbetet presenteras en lösning på problemet med miljöinducerad fasskift genom att utvärdera reglertekniska återkopplande algoritmer. Algoritmerna PID (Proportionell-, Integrerande-, Deriverande regulator) samt ICA (Inkrementell Regleralgoritm, eng: Incremental Control Algorithm) har undersökts och deras prestanda har jämförts med samt utan avskärmning. Algoritmerna har implementerats i en FPGA (fältprogrammerbar grindmatris, eng: Field-Programmable Gate Array) och regulatorn styr en elektrooptisk fasmodulator som kan addera en fasförskjutning till en av ljusstrålarna i MZI:n. Resultat visar att passiv avskärmning inte är tillräckligt utan behöver användas tillsammans med aktiv reglering för att uppnå stabilitet över en längre tidsperiod. Detta examensarbete visar på att en signifikant förbättring i den optiska stabiliteten kan uppnås med aktiv reglering jämfört med en interferometer utan aktiv fasreglering.
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Raju, N. Ravisekhar. "A decoupled converter topology for active compensation of power systems /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5847.
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Paschal, Matthew James 1964. "Compensation techniques for gain-bandwidth effects of active RC filters." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278081.
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The gain-bandwidth (GB) product of an operational amplifier (op amp) can effect the filtering characteristics of an infinite gain, multiple feedback, low pass active RC filter. In this thesis, the characteristics of ideal op amps and actual op amps are compared. The op amp is characterized by a dominant single pole, which is used to develop a third order voltage transfer function that describes the op amp's gain-bandwidth effects on the filter. Optimization theory is used to find adjusted values for the filter's elements to compensate for these GB effects. Of the sixty-five compensation design methods examined with the optimization program GOSPEL, twelve methods produced useful compensation results. The adjusted element values are tabulated and displayed in design graphs for several values of GB and quality factor, Q. The twelve design techniques were verified by simulating the filter with the adjusted element values using PSpice.
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Towliat, Abolhassani Mehdi. "Integrated electric alternators/active filters." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/268.
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In response to energy crisis and power quality concerns, three different methodologies to integrate the concept of active filtering into the alternators are proposed. Wind energy, due to its free availability and its clean and renewable character, ranks as the most promising renewable energy resource that could play a key role in solving the worldwide energy crisis. An Integrated Doubly-fed Electric Alternator/Active filter (IDEA) for wind energy conversion systems is proposed. The proposed IDEA is capable of simultaneous capturing maximum power of wind energy and improving power quality, which are achieved by canceling the most significant and troublesome harmonics of the utility grid and power factor correction and reactive power compensation in the grid. The back-to-back current regulated power converters are employed to excite the rotor of IDEA. The control strategy of rotor-side power converter is based on position sensoreless field oriented control method with higher power density. Analysis and experimental results are presented to demonstrate the effectiveness of the proposed IDEA. In next step, an integrated synchronous machine/active filter is discussed. The proposed technology is essentially a rotating synchronous machine with suitable modification to its field excitation circuit to allow dc and ac excitations. It is shown that by controlling the ac excitation, the 5th and 7th harmonics currents of the utility are compensated. The proposed method is cost effective because it can be applied to existing standby generators in commercial and industrial plants with minimal modification to the excitation circuits. To boost the gain of harmonic compensatory, an advanced electric machine is proposed. An Asymmetric Airgap Concentrated Winding Synchronous Machine (AACWSM) with ac and dc excitation was designed and employed. It is shown that the AACWSM with its unique design, in addition to power generation capability, could be used to compensate the most dominant current harmonics of the utility. The proposed AACWSM can compensate for the 5th and 7th harmonics currents in the grid by controlling the ac field excitation. In addition, the 11th and 13th harmonics currents are also significantly reduced. This system can be used at medium and low voltages for generation or motoring mode of operation.
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Abolhassani, Mehdi Towliat. "Integrated electric alternators/active filters." Texas A&M University, 2004. http://hdl.handle.net/1969.1/268.
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In response to energy crisis and power quality concerns, three different methodologies to integrate the concept of active filtering into the alternators are proposed. Wind energy, due to its free availability and its clean and renewable character, ranks as the most promising renewable energy resource that could play a key role in solving the worldwide energy crisis. An Integrated Doubly-fed Electric Alternator/Active filter (IDEA) for wind energy conversion systems is proposed. The proposed IDEA is capable of simultaneous capturing maximum power of wind energy and improving power quality, which are achieved by canceling the most significant and troublesome harmonics of the utility grid and power factor correction and reactive power compensation in the grid. The back-to-back current regulated power converters are employed to excite the rotor of IDEA. The control strategy of rotor-side power converter is based on position sensoreless field oriented control method with higher power density. Analysis and experimental results are presented to demonstrate the effectiveness of the proposed IDEA. In next step, an integrated synchronous machine/active filter is discussed. The proposed technology is essentially a rotating synchronous machine with suitable modification to its field excitation circuit to allow dc and ac excitations. It is shown that by controlling the ac excitation, the 5th and 7th harmonics currents of the utility are compensated. The proposed method is cost effective because it can be applied to existing standby generators in commercial and industrial plants with minimal modification to the excitation circuits. To boost the gain of harmonic compensatory, an advanced electric machine is proposed. An Asymmetric Airgap Concentrated Winding Synchronous Machine (AACWSM) with ac and dc excitation was designed and employed. It is shown that the AACWSM with its unique design, in addition to power generation capability, could be used to compensate the most dominant current harmonics of the utility. The proposed AACWSM can compensate for the 5th and 7th harmonics currents in the grid by controlling the ac field excitation. In addition, the 11th and 13th harmonics currents are also significantly reduced. This system can be used at medium and low voltages for generation or motoring mode of operation.
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Stöppler, Guido [Verfasser]. "Active compensation of structural oscillations on high dynamic gantry machines / Guido Stöppler." Aachen : Shaker, 2005. http://d-nb.info/1186588349/34.
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Bach, Susan Elizabeth. "Chirp compensation in active mode-locked semiconductor diode laser using a DFB." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36504.
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Ndiaye, Abdoul Ousmane. "Compensation active des ondulations de couple d'un moteur synchrone à aimants permanents." Besançon, 2002. http://www.theses.fr/2002BESA2038.
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Le travail effectué dans ce mémoire présente une méthode de compression des ondulations de couple d'un moteur synchrone à aimants permanents sans pièces polaires. L'objectif est l'amélioration de la qualité de la conversion électromécanique en minimisant les ondulations de couple et les vibrations. Le mémoire commence par une présentation des caractéristiques de couple du moteur synchrone étudié et les différentes causes des ondulations de son couple. Dans le deuxième chapitre, nous avons développé une méthode permettant, à partir du développement harmonique de la force électromotrice d'un moteur asynchrone à aimants sans pièces polaires, de calculer un nombre minimal d'harmoniques de courant permettant de compenser les ondulations de couple tout en optimisant le rendement. Les troisième et quatrième chapitres présentent le banc d'essai et l'étude expérimentale des vibrations. Le banc permet d'une part d'imposer différentes formes d'ondes de courant au moteur asynchrone à l'aide d'un système de contrôle et de commande réalisés avec l'outil dSPACE et d'autre part de relever le comportement vibratoire de l'ensemble du système (banc-moteur)The work carried out in this thesis presents a method of torque ripple compensation in permanent magnets synchronous motor without polar parts. The aim is the improvement of the electromechanical conversion quality by minimizing the torque ripple and the vibrations. The thesis starts with a presentation of the torque characteristics of the studied synchronous motor and the different causes of its torque ripples. In the second chapter, a computation method of optimal current harmonics is developed : starting from the back electromotive force harmonics of a magnet synchronous motor without polar parts, a minimal number of current harmonics are calculated to cancel the torque ripple while optimizing the efficiency. The third and fourth chapters present the test bench and the experimental study of the vibrations. The bench makes it possible one the one hand to fed synchronous motor with various current waveforms using a control system realized with the dSPACE tool and on the other hand to measure the vibrations of the system (bench-motor)
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da, Silva Neddef N. (Nedio). "Active phased array transceiver:an operational compensation for a multiple phase shifter system." Master's thesis, University of Oulu, 2018. http://jultika.oulu.fi/Record/nbnfioulu-201805151790.
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Abstract. The upcoming fifth-generation mobile technology relies on the implementation of beamforming techniques to fulfill the requirements proposed for the 2020 roll-out. One of the processes for stepping up this technique from the high-end applications to the telecommunication mass market is to be able to test, analyze and tune the product according to the specifications. After the manufacturing process, the phased antenna array, beamforming and beam-steering system must be tested against a prediction model, and corrected against deviations due to the uniqueness of the components, with the objective to conform the final product to be in accordance with specifications, while at low cost and time. The aim of this work is to propose and test different procedures for calibrating the phase component of an RF phased array transceiver with multiple phase-shifters. The different proposed procedures are compared in an over-the-air measurement through the performance when applying the beamforming and beam-steering techniques.
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Sverdrup-Thygeson, Jørgen. "Modeling and Simulation of an Active Hydraulic Heave Compensation System for Offshore Cranes." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9531.
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This thesis deals with the mathematical modeling of hydraulic heave compensation systems. When performing operations such as launch and recovery of remote operated vehicles and lowering subsea installation parts to the sea floor, it is important to attenuate unwanted load motion caused by elongation of the cable and heave motion of the vessel. Quite often, such operations must be put off while waiting for the weather to calm down. Extending the window of operations by developing equipment that can handle varying sea states can result in significant cost savings. There exist both electric and hydraulic heave compensation devices, but the main focus of this thesis is on the hydraulic configurations. A mathematical model is developed in Simulink, and simulations are performed for long-crested seas with values corresponding to the average sea conditions in the North Sea.
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Spro, Ole Christian B. "Reactive Power Compensation and Active Filtering Capabilities of the Step-down AC Chopper." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23617.
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The Step-down AC Chopper (hereby referenced as "AC Chopper") has been presented in recent academic papers as a possible solution for reactive compensation. The goal of this project was to investigate and evaluate the topology to see if the praise could be justified. In addition, this project set a goal to take the research one step further by investigating if the uses of the AC Chopper could be expanded to include active filtering. The ability of the AC Chopper converter to produce harmonic current was investigated. This was the first step in developing the AC Chopper's active filtering functionality. Theorems were developed and simulations were performed with both open and closed loop control. The results show that using the AC Chopper to produce harmonic current is very difficult if not impossible. This is due to intrinsic characteristics of the topology which leads to the converter producing multiple harmonics for a single control input frequency. Hence it was concluded that the AC Chopper is not fit for performing active filtering and that the results do not support continuing any further research on the AC Chopper's filtering capabilities.A prototype of the converter was developed and built to compare the simulations against real observed behavior. The development process has been well documented in this thesis. Open loop control of the prototype was successfully implemented. The results show a good relation between the theory and the measured values. There are certain challenges connected to the realization of the AC Chopper, and the ways of dealing with these challenges have been described herein. The topology was also compared to available technology to evaluate the competitiveness regarding reactive compensation at fundamental frequency. The AC Chopper was not found advantageous compared to the VSI, a modern available solution. The efficiency of the AC Chopper has been found to be slightly higher in simulation, but this has yet to be validated with tests on real prototypes. In addition to lacking the filtering capabilities, the AC Chopper has other disadvantages including expensive components and greater volume. Together the findings in this report suggests that the AC Chopper should be limited to use in single phase systems for reactive compensation at fundamental frequency in open loop control.
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Davies, David Bradley. "Analysis of active compensation for shock, vibration, and wind-up in disk drives." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13301.
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Soares, Guilherme Márcio. "Capacitance reduction in off-line led drivers by using active ripple compensation techniques." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/6044.
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Este documento apresenta uma nova técnica para a minimização da ondulação de baixa frequência, típica de conversores para o acionamento de LEDs alimentados a partir da rede elétrica. Esta estratégia baseia-se na modulação em baixa frequência da razão cíclica do conversor de modo que a ondulação de corrente possa ser reduzida e, consequentemente, as capacitâncias de filtragem do conversor possam ser minimizadas. Esta técnica foi desenvolvida para a aplicação em conversores de malha única, como é o caso de conversores de estágio único ou mesmo dois estágios integrados. A modulação da razão cíclica é projetada de maneira que o comportamento de baixa frequência das principais variáveis do conversor seja alterado, permitindo uma redução da ondulação da corrente de saída ao custo de um incremento cotrolado no conteúdo harmônico da corrente de entrada. Duas possíveis metodologias para a implementação da técnica proposta são discutidas ao longo do trabalho. A primeira envolve a injeção de harmônicas específicas no sinal da razão cíclica do conversor através de ramos adicionais na estrutura de controle. Esta abordagem foi aplicada para projetar um controlador de LEDs baseado em um conversor flyback e também em uma topologia integrada baseada na conexão cascata de dois conversores Buck-boost. Este estudo inicial foi expandido para outros conversores e uma análise generalizada acerca da influência da modulação da razão cíclica no comportamento de controladores de LED alimentados a partir da rede elétrica é apresentada. A segunda metodologia para a implementação da compensação ativa da ondulação de baixa frequência do conversor é baseada na otimização de um controlador proporcional-integral a fim de que tal elemento influencie não só no comportamento dinâmico do circuito, mas também na característica de baixa frequência do conversor. Por fim são discutidas as principais contribuições da tese e algumas propostas para trabalhos futuros são apresentadas
This document presents a novel approach for low-frequency output current ripple minimization in off-line light-emitting diode (LED) drivers. This strategy is based on the large-signal modulation of the duty-cycle so that the output ripple can be reduced and, consequently, the required filtering capacitances of the converter can be somehow decreased. This technique is devised to be used on converters in which a single control loop is employed, such as off-line single-stage or integrated converters. The duty-cycle modulation is used to change the shape of the main waveforms of the converter, especially the input and output currents. This allows for a reduction of the output current peak-to-peak ripple while the harmonic content of the input current is increased but kept within the limits imposed by the IEC standard. Two methodologies for implementing the proposed technique are discussed along the text. The first one is related to the injection of harmonic components to the duty cycle signal by means of additional branches inserted in the conventional control structure. This approach was applied to design an off-line flyback-based LED driver and also a circuit based on the Integrated Double Buck-boost converter. This first study was expanded to other topologies and a generalized analysis regarding the impact of the duty cycle modulation on off-line converters is then presented. The second methodology for implementing the ripple compensation is based on the optimization of a proportional-integral controller so that this element is designed to influence not only in the dynamic behavior of the circuit, but also in its low-frequency characteristic. Finally, the main contributions of this work are discussed and the proposals for future works are presented.
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Reyes-Moraga, Eduardo Felipe. "Predictive control of a direct series resonant converter with active output voltage compensation." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/31263/.
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Modern high power supplies are based on resonant converters in order to use high frequency reactive elements (for reduced size) without sacrificing converter efficiency. In an effort to achieve compact high power supplies, direct power converter topologies have been considered, since these are mainly characterised by their high power density. A direct resonant converter topology combines matrix converters with conventional resonant converters. This work focused on achieving high quality input/output power and high efficiency. Thus, this thesis presents the research on the control of a direct series resonant converter. Since the resonant converter allows a sinusoidal high frequency output current to be generated, zero current switching (ZCS) was considered to reduce the power losses. Hence, since the converter is switched at every zero crossing of the output current (fixed period), model predictive control was considered. Different predictive approaches for controlling the input and output currents were developed and analysed, however, owing to the characteristics of the topology, these strategies resulted in a suboptimal control. Therefore, in order to improve the input and output qualities (reduce distortion), an output voltage compensation strategy was proposed. This compensation approach is based on adding an H-bridge converter in series between the matrix converter and the resonant tank. This converter improves the voltage applied to the resonant tank, thus, reducing the distortion at the output and, as a consequence, also the distortion at the input. The H-bridge converter utilises only a small capacitor on the dc side in comparison with conventional resonant converters and operates at a low voltage. Simulations were carried out using MATLAB/Simulink and an experimental prototype was built to validate the strategies proposed, achieving a reduction of the input current THD from 4.4% to 2.7%, a reduction of the output current distortion of approximately 40% and an analytically derived efficiency of 89.5%.
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Bó, Antônio Padilha Lanari. "Compensation Active de Tremblements Pathologiques des Membres Supérieurs via la Stimulation Electrique Fonctionnelle." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20162/document.
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Le tremblement, défini comme un mouvement rythmique involontaire, est un des mouvements anormaux les plus fréquents. Le tremblement n'est pas une pathologie mortelle, mais elle diminue souvent considérablement la qualité de vie de la personne. Les traitements efficaces ne sont pas encore disponibles, puisque les solutions pharmacologiques et chirurgicales souffrent encore de limitations en termes d'efficacité, de risques et de coûts. Une alternative consiste à utiliser des technologies d'assistance, tels que les exosquelettes ou la Stimulation Électrique Fonctionnelle (SEF).Néanmoins, la conception de systèmes actifs de compensation des tremblements présente plusieurs défis. Un tel système doit être capable, par exemple, d'atténuer les tremblements tout en minimisant la fatigue, la douleur et l'inconfort induit. Il doit aussi distinguer entre le tremblement et le mouvement volontaire, afin de réduire les interférences sur les mouvements intentionnels.Cette thèse se concentre donc sur l'évaluation de l'usage de la SEF pour atténuer le tremblement. Une première contribution concerne le développement des modèles neuromusculosquelettiques pour étudier l'influence des boucles réflexes sur la dynamique du tremblement, ainsi que la modulation de l'impédance de l'articulation via la co-contraction induite par la SEF. Un algorithme pour estimer en ligne le tremblement et ses caractéristiques tout en filtrant le mouvement volontaire a été proposé et validé sur patients. Enfin, un système SEF pour atténuer le tremblement basé sur le contrôle d'impédance a été conçu et évalué sur patients, alors qu'une deuxième stratégie en boucle fermée a été testée sur des sujets sainsTremor, defined as an involuntary, approximately rhythmic and roughly sinusoidal movement, is one of the most common movement disorders. It is not a life-threatening pathology, but it often decreases significantly the person's quality of life. Today, effective treatments for pathological tremor are not yet available, since current pharmacological and surgical alternatives still present limitations with respect to effectiveness, risks, and costs. A different approach is the use of assistive technologies, such as upper limb exoskeletons or Functional Electrical Stimulation (FES).Nevertheless, the design of active tremor compensation systems based on these technologies presents several challenges. Such a system must be able, for instance, to attenuate tremor while minimizing the induced fatigue, pain, and discomfort. Also, it must be able to distinguish between pathological tremor and voluntary motion, in order to reduce interference on intentional movements.This thesis is focused then in evaluating the use of FES to attenuate the effects of tremor. A first contribution concerns the use of neuromusculoskeletal models to study the effects reflex pathways may produce on tremor dynamics, as well as how FES-induced co-contraction may modulate joint impedance. Also, an online algorithm to estimate tremor and its features while simultaneously filtering voluntary motion has been proposed and validated with tremor patients. Finally, a FES system to attenuate tremor based on impedance control has been designed and evaluated on tremor patients, while a second strategy using closed-loop FES control has been tested on healthy subjects
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Chen, Weiqun. "A Microcontroller Configured Active Analog Phase Shifter at 1.96GHz." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1273841250.
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Reader, Daniel Martin. "Nonlinear Mr Model Inversion for Semi-Active Control Enhancement With Open-Loop Force Compensation." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32660.
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The increased prevalence of semi-active control systems is largely due to the emergence of cost effective commercially available controllable damper technology such as Magneto-Rheological (MR) devices. Unfortunately, MR dampers exhibit highly nonlinear behavior, thus presenting an often over-looked complexity to the control system designer. With regards to controlling dampers, the well-known Skyhook Damping control algorithm has enjoyed great success for both fully active and semi-active control problems. The Skyhook design strategy is to create a control force that emulates what a passive linear damper would create when connected to an inertial reference frame. Skyhook control is device independent since it generates a desired control force command output that must be produced by the control system.
For simplicity, MR dampers are often assumed to have a linear relationship between the current input and the force output at a given relative velocity. Often this assumption is made implicitly and without knowledge of the underlying nonlinearity. This thesis shows that the overall performance of a semi-active Skyhook control system can be improved by explicitly inverting the nonlinear relationship between input current and output force. The proposed modification will work with any semi-active control algorithm, such as Skyhook, to insure that the controller performance is at least as good as the performance without the proposed modification. This technique is demonstrated through simulation on a quarter-vehicle system.
Hysteretic damping effects are incorporated into the modification by application of simple open loop force compensation. Laboratory testing of the hysteretic inversion process was performed with the goal of emulating an ideal linear damper without hysteresis. These results are compared with the implicit assumption thus providing a basis for validating the benefits of the improved methodology.
Master of Science
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Lowinsky, Luc Anthony. "Nouvelle topologie de Compensateur de Puissance Réactive pour les Réseaux Ferrés 25 kV / 50 Hz." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0036/document.
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Le travail présenté dans ce mémoire s’est déroulé dans le cadre d’une collaboration entre le groupe Convertisseur Statique du laboratoire LAPLACE et le département " Installations Fixes de Traction Electrique " de la Direction de l’Ingénierie de la SNCF. Aujourd'hui, la majorité du trafic sur le réseau ferré monophasé 25 kV / 50 Hz est assurée par des locomotives équipées de redresseurs contrôlés à thyristors. Du fait de l'augmentation du trafic, l'utilisation de ces locomotives nécessite la mise en place de moyen de compensation de puissance réactive afin de maintenir la tension caténaire à un niveau acceptable et de réduire la facture en énergie réactive. La correction du facteur de déplacement est réalisée en partie par des batteries de compensation fixes dont lapuissance est limitée par la tension maximale admissible à vide sur la caténaire. Afin d’adapter le niveau de compensation à la consommation, la partie fixe est complétée par un dispositif réglable basé sur une réactance contrôlée par des thyristors. Bien qu’il soit simple dans son principe, ce dispositif nécessite un filtrage des harmoniques en basse fréquence avec des circuits LC volumineux. L’objectif de cette thèse est de proposer une nouvelle topologie de compensateur de puissance réactive à haut rendement et utilisant un contrôle à modulation de largeur d’impulsion dans le but de minimiser le volume des éléments de filtrage. La première partie de ce mémoire est consacrée à une étude comparative de différentes topologies du point de vue des pertes dans les semi-conducteurs et du dimensionnement des éléments de filtrage associés. Les résultats de cette étude montrent que les topologies à base de gradateurs MLI, constituent les solutions les plus intéressantes pour réaliser le compensateur. La deuxième partie du travail concerne l’étude de l’insertion d’un compensateur à base de gradateurs MLI sur le réseau ferré avec la prise en compte des interactions harmoniques. Le cas d’étude concerne une sous-station où doit être implantée une compensation variable de 3 MVAR. Un relevé des courants délivrés par la sous-station a été effectué dans le but d’analyser leur contenu harmonique. Une modélisation de la sous-station et du compensateur est ensuite proposée et des simulations temporelles de l’ensemble sont réalisées en prenant en compte les formes d’ondes réelles des courants absorbés par les trains. Finalement, cette étude par simulation permet d’affiner le dimensionnement du compensateur à gradateurs MLI et des éléments de filtrage associés. Elle met en évidence l’avantage d’une solution, avec des gradateurs MLI en montage élévateur de tension, qui fonctionne sans transformateur et réutilise les batteries de compensation fixes déjà installées en sous-station à la fois comme diviseur de tension et éléments de filtrage. Afin de valider le principe de cette nouvelle topologie de compensateur statique de puissance réactive, un démonstrateur de 1,2 MVAR est mis en oeuvre et testé sur une plateforme d'essai de la SNCFThe work presented in this thesis is the result of collaboration between the Static Converters research group of LAPLACE Laboratory and the department "Installations Fixes de Traction Electrique" of the Engineering Division of the French Railways company, SNCF. Nowadays, most of the traffic in 25 kV – 50 Hz lines is achieved by old locomotives equipped with thyristor rectifiers. As traffic and load increase, reactive power compensation devices are required to keep the overhead line voltage at acceptable level and to reduce the spending for reactive power. The basic power factor correction is completed by fixed compensation banks. But the difficulty of such configuration is the no-load operation of overhead lines. The voltage can increase out of the 29 kV standard limit and to avoid this problem, variable reactive power compensator is often added to the fixed compensation banks. Nowadays, SNCF is equipped with thyristor based static VAR compensators (SVC). The main drawback of this topology is the requirement of a large LC shunt filter tuned for the third harmonic. The goal of this thesis is to find a new high-efficiency topology of STATic COMpensator (STATCOM) using PWM control to minimize the filtering components. The first part of this thesis focuses on a comparative study of different topologies in terms of semiconductor losses and filter elements size. The results of this study show that the topologies based on PWM AC Chopper are the most interesting solutions to achieve the compensator. The second part of the work concerns the influence of the connection of a STATCOM to a substation and focuses on the harmonic interactions with locomotives. The study case concerns a high traffic substation where a 3 MVAR STATCOM should be installed. Substation output current measurement was carried out in order to analyze its harmonic content. Models of the substation and the STATCOM are then proposed and simulations using real current waveforms are performed. Finally, this simulation study helps to refine the features of the AC Chopper topology and its filter elements. It highlights the advantage of a solution, with boost AC Choppers which operate without transformer and reuse the fixed compensation banks already installed in the substation as voltage divider and filter. To validate the principle of this new topology of STATCOM, a 1.2 MVAR prototype is built in LAPLACE laboratory and tested on a SNCF test platform
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Humphreys, Heather Celeste. "Modeling and compensation for biodynamic feedthrough in backhoe operation." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37254.
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Biodynamic feedthrough occurs in many types of operator controlled machines where the operator is a passenger and the motion of the controlled machine excites motion of the human operator, creating unwanted feedback. It is a significant cause for control performance degradation in backhoes. In this research, the problem of biodynamic feedthrough is investigated in a backhoe control system. For simplification, the system is limited to a single degree of freedom. Several controller based approaches are investigated to reduce cab vibration, while maintaining cylinder tracking performance. These controllers are tested in hardware, with and without the human operator and associated biodynamic feedthrough. The effect of this cab vibration reduction on biodynamic feedthrough is tested in a small set of human subject tests. The results indicate that some vibration reduction and improvement in the operator's control performance can be achieved by adding cab vibration compensation.
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Prasai, Anish. "Direct dynamic control of impedance for VAR and harmonic compensation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42816.
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Reactive power is critical to reliable operation of the modern AC power system. There is a plethora of motor-loads, transformers, and power-electronic loads connected to the power grid, which consume reactive power for normal operation. Transmission lines also consume reactive power when they are loaded above their surge impedance loading (SIL). Reactive power can exact opportunity cost due to reduced capacity of the lines to carry real power, which in turn lowers revenue. Most transmission owners (TOs) levy large penalties against load serving entities (LSEs), industrial facilities, and other end-use customers, who consume more than their allotted amount, as measured by their power factor. These penalties are to incentivize their customers to meet their reactive power needs locally as well as to recuperate the TOs' financial losses.
Harmonic pollution is another factor that prevents the optimal operation of the grid and the connected loads. Harmonics are attributable to proliferation of the diode-rectifier- or thyristor-rectifier-interfaced loads such as variable speed ac drives and power supplies in server farms, electric arc furnaces, and other non-linear loads, which are widely employed by the industrial sector. With wider adoption of harmonic-rich loads by the consumer sector as well, such as HDTVs and compact fluorescent lamps (CFLs), greater level of triplen harmonics associated with single-phase loads are also increasingly seen on the distribution grid. The increasing penetration of renewable resources and electrification of light-duty vehicles are expected to further aggravate the stresses and congestion on the utility grid.
Reactive power compensation is necessary for supporting the AC grid and maintaining a healthy voltage stability margin. Compensation can also enhance the utilization of system capacity, lower system losses, provide fault ride-through, and enable a quick fault recovery. Existing VAR and harmonic compensation technologies are either too expensive or inadequate to meet the dynamic needs of the modern and the future power system.
This dissertation presents a novel class of Dynamic VAR and Harmonic Compensators (DVHCs) for supplying or absorbing reactive power and providing harmonic filtering, where the compensation is in shunt with the line and the load. The underlying concept is based on augmenting a static or passive component like a capacitor or an inductor with a direct AC converter and imbuing the passive component with dynamic properties. The direct AC converter can be configured as a buck, a boost, or a buck-boost. A `fail-normal' switch is an integral part of the DVHCs that bypasses the converter when it fails, preserving the original functionality and the reliability of the passive component. The DVHCs are modular and scalable such that they can be employed in applications ranging from residential and industrial with voltages less than 480 V, to power distribution level with voltages as high as 35 kV. The Dynamic Inductor (D-IND) and the Dynamic Capacitor (D-CAP) are subclasses of the DVHCs. As the applications for supplying leading VARs are more prevalent, the primary focus of this work is on the buck, the boost, and the buck-boost configurations of the D-CAP.
To understand the characteristics and operation of the DVHCs, this work has developed time-domain models for analyzing the transient and dynamic behavior; frequency-domain models for understanding the harmonic interactions and the steady-state relationships between switch duty and current harmonics; and small-signal models for studying the dynamics of the converter due to various perturbations. The small-signal models also enable extraction of transfer functions in designing controllers and assessing stability margins.
Control architectures and techniques are presented for effectively controlling the D-CAP when commutating the semiconductor devices with both high and low switching frequencies.
In modularly scaling the DVHCs to higher voltages, three medium-voltage topologies are discussed. They are based on series-connecting fractionally-rated devices, AC flying capacitors, and series cascading multiple two-level cells. These implementations allow direct connect to the medium-voltage grid, thereby obviating the use of transformers, and subsequently reducing the losses, cost, complexity, and footprint. A novel AC snubber concept is proposed to provide safe commutation of the AC switches, fault tolerance by managing the energy trapped in parasitics and filters, and to enable dynamic and static voltage sharing when integrated around the series-connected devices.
Design equations for selecting and rating the devices and components in the buck, the boost, and the buck-boost configurations of the D-CAP are presented. Three sets of example designs, with one at low-voltage and two at medium-voltage, are discussed to demonstrate the typical size and ratings of the various components under realistic operating conditions.
Measurements and the related discussions of a 40 kVA buck D-CAP prototype built to validate the effectiveness of the proposed concepts are presented.
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Khalsa, Harnaak Singh. "Generalised power components definitions for single and three-phase electrical power systems under non-sinusoidal and nonlinear conditions." Monash University. Faculty of Engineering. Department of Electrical and Computer Systems Engineering, 2008. http://arrow.monash.edu.au/hdl/1959.1/42420.
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There is a need for generalised definitions of electrical powers to provide a simultaneous common base for measurement, compensation, power quality and identification of source of distortion. The major problem area today is definitions of powers in the presence of harmonics and nonlinear loads in the electrical power system. In such a scenario, there is a problem to accurately measure especially reactive (nonactive) power. This is important for accurate energy billing. Another important area is the mitigation equipment used to remove unwanted polluting quantities from the power system. Definitions of powers have an important role to play in providing the correct information for the optimal design and performance of such equipment. Evaluation of the quality of the power system to enable appropriate allocation costs to those causing deterioration in the power quality also cannot be discounted. To enable this cost allocation, there is a need to identify the polluters and the definitions should indicate degradation in power quality as well as identify the source of this degradation. Finally, it would be very useful if the definitions could also be used to perform a general analysis of the power system. This thesis commenced with investigation of the problem with an in-depth study of the existing definitions, and what other researchers have indicated about this problem, from the definitions perspective. The issues identified with current definitions are that some definitions do not possess the attributes that are related to source-load properties, and others are based on mathematical consideration and lack physical meaning. One issue in measurement of nonactive power is its nature of having zero average value. Another contributing factor is that the presence of source impedance is neglected in definitions. The use of RMS quantities to determine powers, especially instantaneous powers, in the presence of multi-frequency voltages and currents also contributes to the problem. Additionally, RMS based definitions are based on heating effect while not all sourceload relationships are totally of a heating nature. The RMS based definitions also do not satisfy the energy conservation principle. Another issue is that though harmonic currents are used, current definitions still utilise the RMS value of the voltage wave thus losing harmonic information. The solution is to decompose, as accurately as possible, the total instantaneous power into active and nonactive components utilising DC, fundamental and harmonics of voltage and current as well as being based on the power system properties. To enable this, the load model must closely represent the reality. This thesis presents the new instantaneous power definitions to achieve this. In addition to the fundamental, five sub-components for each of the active and nonactive parts are defined. The definitions are based on both the voltage and current DC, fundamental and harmonic components thus retaining harmonic information. Thus these definitions are not only mathematically based but also have a direct relationship with the load. The definitions do not make the assumption of zero source impedance. With good knowledge of the time profile of active and nonactive power components, an accurate time-domain measurement of the active and nonactive power is achieved. The components of powers introduced in the proposed definitions can be utilised to gauge power quality, to identify the source of distortion and to achieve optimal compensation. Based on the new instantaneous power definitions, the definitions for average values of the powers are also proposed. The recognition of positive going and negative going parts of the nonactive power waveform in defining the average nonactive power alleviates the problem of the “zero average nature” of nonactive power. It also retains energy information and satisfies the principle of energy conservation. The new definitions are evaluated for linear and non-linear loads in the presence of harmonics using benchmark case studies. Evaluation results demonstrate good performance of the proposed definitions. The practical applications of the definitions are explored with a number of examples from the areas of measurement of power and energy, compensation, detection of source of distortion and power quality. An application example showing the capability of the definitions in general analysis of a system is also presented. Good and useful results are obtained for all these examples. The proposed definitions are implemented on prototype systems with digital signal processors to demonstrate their practical usability. The proposed definitions are shown to be consistent with the traditional definitions under the conventional sinusoidal conditions, and their relationships to the commonly used existing definitions are also revealed.
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Lee, Bong-ha. "Active power system compensator with fuzzy vector controller." Thesis, Queensland University of Technology, 2002. https://eprints.qut.edu.au/36152/1/36152_Lee_2002.pdf.
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Active power compensation of reactive power and harmonic distortion caused by non-linear loads can be achieved by using a current controlled, voltage-source
inverter based compensator. The compensation technique used injected waveform control along with vector control based on instantaneous power theory allows a general purpose inverter based compensator to perform full
compensation of var, power factor and harmonic distortion and other non-linear components. Dr. Keith Hoffman has developed an instantaneous control algorithm capable of
eliminating harmonics and calculating the in-phase fundamental load current needed to supply the real power at the same time. The application of his technique to a new 'Switch State Coarse Fuzzy Vector Controller' is discussed in detail as well as the operation of the experimental system. The author has also
developed a compensator system that exhibits accurate control by using the instantaneously determined reference current compared with the supply current directly rather than using compensator current control as in previous methods. In microprocessor control applications, the power semiconductor switching speeds of a compensator is limited by the microprocessor calculation times. It is
demonstrated that simplifying the control circuit using a vector controller and reducing logic calculation times using coarse fuzzy logic control can be an effective and simple technique utilising both microprocessor and analogue based calculations. Two types of controller where investigated with one being a microprocessor-based fuzzification and the other an analogue comparator-based
fuzzification, are demonstrated and compared with each other. Results from the undertaken experiments show practical relevance of the developed instantaneous reference current vector calculator and 'Switch State
Coarse Fuzzy Vector Controller'. Useful techniques that integrate fuzzy control theory with conventional and modem control algorithms and switching strategies
are discussed in detail.
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Dang, Anh X. H. "Theoretical and experimental development of an active acceleration compensation platform manipulator for transport of delicate objects." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17277.
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Ingram, David. "An Evaluation of Harmonic Isolation Techniques for Three Phase Active Filtering." Thesis, University of Canterbury. Electrical and Computer Engineering, 1998. http://hdl.handle.net/10092/1260.
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Recent advances in power electronics have lead to the wide spread adoption of advanced power supplies and energy efficient devices. This has lead to increased levels of harmonic currents in power systems, degrading the performance of electrical machinery and interfering with telecommunication services. Active filters provide a solution to these problems by compensating for the distorted currents drawn by non-linear loads. Optimal methods for controlling these active filters have been determined by computer simulation and experimental implementation. Methods used for isolating the harmonic content of an unbalanced three phase load current were compared by computer simulations. A technique based on the Fast Fourier Transform (FFT) was developed as part of this work and shown to perform favourably. Notch Filtering, Sinusoidal Subtraction, Instantaneous Reactive Power Theory, Synchronous Reference Frame and Fast Fourier Transform methods were simulated. The methods shown to be suitable for compensation of three phase unbalanced loads were implemented in a Digital Signal Processor to evaluate true performance. These methods were Notch Filtering, Sinusoidal Subtraction, Fast Fourier Transform, and a High Pass Filter based method. A completely digital hysteresis current controller for a three phase active filter inverter has been developed and implemented with a Field Programmable Gate Array. This controller interfaces directly to a digital signal processor and is resistant to electromagnetic interference. Results from the experimental hardware verified that the active filter model used for simulation is accurate, and may be used for further development of harmonic isolation methods. A technique using notch filtering gives the best performance for steady loads, with the FFT based technique giving the most flexible operation for a range of load current characteristics. Novel use of the FFT based harmonic isolation technique allows selective cancellation of individual harmonics, with particular application to multiple shunt filters connected in parallel.
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Wang, Lei. "Design and implementation of a three-phase three-wire thyristor controlled LC-coupling hybrid active power filter with low dc-link voltage and wide compensation range." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691876.
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Schneider, Jason C., and Neil L. Ebuen. "The potential effects of the Defense Business Board military compensation task groups 2011 recommendations on active-duty service member retirement." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27899.
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Outstanding ThesisApproved for public release; distribution is unlimited
In July 2011, the Defense Business Board (DBB) made recommendations to the Secretary of Defense for modernizing the military retirement system. If implemented, the plan would significantly modify military retirement as it has existed since its inception, shifting it from a defined benefit plan to a defined contribution plan. In this study, we compared the current defined benefit retirement plan to a hypothetical, retrospective defined contribution plan using the constraints proposed by the Defense Business Board Military Compensation Task Group. We also gathered service members sentiments about the current military retirement system and proposed changes. This is an important topic because it revealed the potential financial effects on service members retirement savings, and government and departmental challenges should a new retirement system be implemented. In this study, we created a mathematical model to simulate accumulated savings under the proposed defined contribution (DC) plan, and then compared it to the lump-sum equivalent of the existing defined benefit (DB) plan. Our model considered three investment strategies for asset allocation for active-duty personnel (i.e., officer and enlisted) spanning a 20-year career beginning in January 1, 1991, and ending in December 31, 2010. Additionally, our study surveyed active-duty service members assigned to the Naval Postgraduate School and personnel assigned to the II Marines Expeditionary Force. Through the survey, we gathered feedback on service members attitudes toward military retirement, in general, and proposed changes to the military retirement system. For an officer, the model showed that under a DC plan, accumulated savings were only 37.5% of the lump-sum equivalent of total annuities received under the current DB plan. Likewise, for an enlisted service member, this value was 31.9%. The survey showed that an overwhelming majority of service members are in favor of retaining the current DB retirement system, or, if the retirement system must be replaced, doing so gradually.
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Zafeiropoluos, Andreas. "An MMC-based topology with Dual-Active-Bridge power channels for load balancing in 50 Hz-railway applications." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201656.
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The purpose of this thesis report is to investigate challenges related to railway electrification. Inac-railway systems, trains are most often single-phase loads, which can create significantunbalances in the grid, when fed directly from two adjacent phases. To enhance power quality atthe railway feeding point, one alternative is to design the system such as the power is fed to thecatenary through Static Frequency Converters (SFCs), which can be a costly solution. Anotheroption is to use Static Compensators (STATCOMs) in shunt connections, handling only theunbalanced amount of power, in order to symmetrize the railway load as seen from the grid side.Modular multilevel converters (MMCs) are the state of the art solutions for medium- and highvoltage/power converter applications, such as load balancing and reactive-power compensation.This project will focus on analyzing Modular Multilevel Converter (MMC) topologies to be usedas load balancers in railway systems. However, the specific requirements of this application reveala potential weakness of MMCs. That is the asymmetrical character of the load may require muchhigher device rating in an MMC compared to a conventional converter, due to the symmetrizingcomponents to rebalance the capacitor voltages in the submodules.This project analyzes a reduced MMC-based topology with only two branches in order to meet therailway load-balancing characteristics. This chain-link compensator uses dc-dc converters tofacilitate power channels in order to restore the power imbalance, without overrating thesemiconductors in the main current path.Syftet med detta examensarbete är att studera de svårigheter som elektrifierade järnvägar står inför.När systemet utgörs av växelström kan tågen ses som en enfas last, vilket kan skapa avsevärdaobalanser i nätet då det matas från två intilliggande faser. En alternativ systemdesign för att uppnåen god effekt leverans uppnås då effekten är matad till kontaktledningen genom statiska frekvensomräknare (SFCs), detta kan dock vara en kostsam lösning. Ett annat alternativ är att användastatisk shunt kompensation (STATCOMs) som selektivt kan hantera den obalanserade effekten föratt uppnå symmetri och balans i järnvägslasten, sett från nätets sida.Modulära multiomriktare (MMCs) är en ledande teknik för omriktare till applikationer på mellanochhögspännings nivå, till exempel för lastbalans och reaktiv kompensering. Detta projektanalyserar modulära multiomriktare för lastbalansering i järnvägssystem. Kraven för dennaapplikation leder till en potentiell svaghet i MMCs där den asymmetriska karaktären på lastenkräver högre märkeffekt jämfört med konventionella omriktare. Detta på grund av de komponentersom återskapar symmetri och balans i kondensator spänningarna i submodulerna.Här analyseras en reducerad variant av MMC-baserad topologi med enbart två grenar för att mötakraven på järnvägens lastbalans. Denna kedjelänk-kompensator använder dc-dc omriktare för attstyra effektflödet till lasten vid obalanserad effekt, utan att för den skull överdimensionerahalvledarna i den ordinarie strömvägen.
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Xue, Kai. "Modal filtering for active control of floor vibration under impact loading." Kyoto University, 2018. http://hdl.handle.net/2433/232024.
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Mérad, Manelle. "Investigations on upper limb prosthesis control with an active elbow." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066615/document.
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Les progrès de la mécatronique ont permis d’améliorer les prothèses du membre supérieur en augmentant le catalogue des mouvements prothétiques. Cependant, un fossé se creuse entre les capacités technologiques de la prothèse et leur méthode de contrôle. La commande myoélectrique, qui est la méthode la plus répandue, reste complexe, notamment pour les personnes amputées au niveau trans-huméral qui peuvent avoir un coude actif en plus de la main et du poignet motorisés. Une approche intéressante consiste à utiliser la mobilité du membre résiduel, présente chez la plupart des amputés trans-huméraux, pour contrôler des articulations prothétiques distales comme le coude. Les mouvements du coude sont couplés aux mouvements du membre résiduel selon un modèle de coordination épaule/coude saine. Cette thèse étudie une stratégie de commande d’un coude prothétique utilisant les mouvements du membre résiduel, mesuré par des centrales inertielles, et nos connaissances du contrôle moteur humain. Pour cela, un modèle de la coordination épaule/coude a été construit à partir d’enregistrements de gestes sains de préhension. Ce modèle, implémenté sur un prototype de prothèse, a été testé par 10 individus sains équipés du prototype afin de valider le concept, puis par 6 personnes amputées. Ces dernières ont aussi réalisé la tâche avec une commande myoélectrique conventionnelle afin de comparer les résultats. La commande couplant automatiquement les mouvements de l’épaule et du coude s’est montrée satisfaisante en termes de facilité d’utilisation et de réduction des stratégies de compensationProgress in mechatronics has enabled the improvement of upper limb prosthetics increasing the grasps catalog. However, a gap has been growing between the prosthesis technological possibilities and the methods to control it. Indeed, common myoelectric control strategy remains complex, especially for transhumeral amputees who can have an active elbow in addition to a prosthetic wrist and hand. Since most transhumeral amputees have a mobile residual limb, an interesting approach aims at utilizing this mobility to control intermediate prosthetic joints, like the elbow, based on the shoulder/elbow coordination observed in healthy movements. This thesis investigates the possibility of controlling an active prosthetic elbow using the residual limb motion, measured with inertial measurement units, and knowledge of the human motor control. A primary focus has been targeting the reaching movement for which a model has been built using regression tools and kinematic data from several healthy individuals. The model, implemented on a prosthesis prototype, has been tested with 10 healthy participants wearing the prototype to validate the concept, and with 6 amputated individuals. These participants also performed the task with a conventional myoelectric control strategy for comparison purpose. The results show that the inter-joint coordination-based control strategy is satisfying in terms of intuitiveness and reduction of the compensatory strategies
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Wang, Yu. "Tunable C Band Coupled-C BPF with Resonators Using Active Capacitor and Inductor." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1472479817.
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Barka, Noureddine. "Développement d'un système de mesure en temps réel des erreurs dans les machines-outils à axes multiples pour une compensation active." Thèse, [Rimouski, Québec] : Université du Québec à Rimouski, 2005.
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Thèse (M. Sc.) - Université du Québec à Rimouski, 2005.Titre de lʹécran-titre (visionné le 31 août 2006). Mémoire présenté à l'Université du Québec à Rimouski comme exigence partielle du programme de maîtrise en ingénierie. Comprend un résumé. CaQRU CaQRU CaQRU Bibliogr.: f. 97-99. Paraît aussi en éd. imprimée. CaQRU
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Zhang, Yigong. "ACTIVE CURRENT INJECTION METHOD FOR LIMITING GROUND FAULT CURRENT HARMONICS IN UNDERGROUND COAL MINES." UKnowledge, 2014. http://uknowledge.uky.edu/mng_etds/15.
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Current practice in U.S. underground coal mine high-voltage distribution systems is to attempt to limit ground fault current to 25 Amperes and de-energize the circuit at 10 Amperes. However, the significant amount of system capacitance due to the use of shielded cables can cause ground fault current to be two or three times the intended ground fault limit. Consequently, this practice can cause several issues such as ground fault currents significantly exceeding the neutral grounding resistor current limit, loss of relay selectivity in the distribution system, and transient overvoltages in certain ground fault situations. These issues are solved to some extent by using a resonance grounded system, currently used in some other countries. However, a shortcoming of traditional resonance grounded systems is the inability to deal with the harmonic components existing in ground fault current. With the increasing use of nonlinear sources such as variable frequency drives, the proportion of harmonic components in ground fault current can be significant. Consequently, although the fundamental component can be almost fully compensated in a traditional resonance grounded system, the harmonic components can still be large enough to maintain arcing and cause personal injury and equipment damage. In this dissertation, a novel method is developed to perform real-time prediction of the harmonics in ground fault currents. Methods for neutralizing the ground fault current harmonics and identifying ground fault location are also developed. Results indicate that the combination of traditional high-resistance grounding and active current injection to neutralize harmonics in the ground fault has the potential to significantly reduce the total ground fault current and reduce arc and flash hazards during ground faults in high voltage distribution systems.
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Raimondo, Giuliano. "Power quality improvements in 25kV 50 Hz railway substation based on chopper controlled impedances." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0004/document.
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Ce travail est le résultat d'une collaboration entre le laboratoire LAPLACE, la "Seconda Università degli Studi di Napoli" (SUN) et la Société National des Chemins de fer Français SNCF. Le sujet de recherche concerne l'utilisation de dispositifs électroniques de puissance dans les sous stations ferroviaires 25kV/50Hz afin d’améliorer la qualité de l'énergie électrique. Dans le transport ferroviaire, le système d'électrification monophasé 25kV/50Hz est largement diffusé en particulier pour les lignes ferroviaires à grande vitesse. Bien qu'aujourd'hui les systèmes d’alimentation en courant continu soient encore largement utilisés, l'adoption du courant alternatif monophasé offre des avantages économiques pour les infrastructures d'environ 30% en termes d'investissement, d'exploitation et d'entretien. Initialement, compte tenu de la simplicité du circuit, il n'y avait aucune nécessité d'intégrer de l'électronique de puissance dans les sous stations. Toutefois, au cours de la décennie passée, l'intérêt pour ces équipements est apparu car ils peuvent apporter une solution d'optimisation du réseau lorsque le trafic augmente ou lorsqu’une nouvelle sous station est envisagée. Deux principaux types de dispositifs sont installés aujourd'hui sur le réseau ferré français : les compensateurs de puissance réactive et les compensateurs de déséquilibre de tension. Cette thèse présente de nouvelles topologies de compensateurs basées sur le concept d’impédances contrôlées par gradateur MLI. Comparées aux solutions existantes, ces topologies ont des caractéristiques particulièrement intéressantes en termes de pertes dans les semi-conducteurs et de volume des composants réactifs. Le manuscrit contient trois parties principales: La première partie présente le principe de l’électrification en 25kV/50Hz et souligne l’intérêt d’installer des moyens de compensation statique dans les sous stations. Après une description des solutions actuellement utilisées, le concept d’impédance contrôlée par gradateur MLI (CCI : Chopper Controlled Impedance ) est ensuite présenté. La deuxième partie du travail concerne l'utilisation du concept de CCI pour la compensation de puissance réactive. La sous-station SNCF de Revest est considérée comme cas d’étude. Celle-ci est équipée d'un transformateur monophasé de 60MVA dont le primaire est connecté à une ligne de transport 225kV. Deux topologies de compensateur de puissance réactive, basées sur des montages abaisseur ou élévateur de tension sont présentées. Le dimensionnement des gradateurs est effectué sur la base d'une campagne de mesures réalisée à la sous station. Des simulations numériques utilisant des formes d’ondes réelles de courant et de tension sont présentées. Des résultats expérimentaux effectués à la plateforme de test de la SNCF sur un prototype de 1,2MVAR permettent de valider le concept de CCI. La dernière partie du travail concerne le problème du déséquilibre de tension en amont de la sous station. Un circuit de Steinmetz « actif », toujours basée sur des gradateurs MLI, est présenté et étudié. La sous station SNCF d'Evron est alors considérée comme cas étude. Celle-ci comporte un transformateur de 32MVA et est connectée à une ligne de transmission 90kV. Les mesures effectuées sur le site permettent le dimensionnement du compensateur ainsi que l’utilisation des formes d'onde réelles de courant et de tension dans les simulations numériques. Une comparaison avec des solutions classiques basées sur des onduleurs 2 niveaux et 3 niveaux souligne les avantages de la solution proposée. Ainsi, les résultats des calculs et des simulations montrent que l'énergie stockée dans les éléments réactifs est réduite d’un facteur six et que les pertes dans les semi-conducteurs sont réduites de 40%. Des résultats expérimentaux obtenus sur une maquette de 1.5 kVA permettent de valider le principe du circuit de Steinmetz actifThis work is the result of collaboration between the LAPLACE laboratory, the “Seconda Università degli Studi di Napoli” (SUN) and the French national railways operator SNCF. The research topic treated herein concerns the use of power electronic devices in 25kV/50Hz railways substations to achieve power quality improvements. In railway transportation, single-phase 25kV-50Hz electrification system is widely diffused especially for high-speed railway applications. Although electrified DC systems are still widely applied, the adoption of AC single-phase system offers economical advantages for the infrastructures of about 30% in terms of investment, exploitation and maintenance. In early ages, due to its very simple diagram, there was no necessity to integrate power electronics in substations. However, for the last decade, the interest in power electronic equipments raised since they can provide the solution for network optimization when traffic increases or when a difficulty is foreseen for a substation implementation. Two types of devices are implemented today on the French Railway Network: Reactive Power compensators and Voltage Unbalance compensators. This thesis presents an investigation into new topologies based on the concept of “Chopper Controlled Impedances”(CCI). Compared to existing solutions, the new topologies show interesting features in terms of semi-conductor losses reduction and volume of reactive components. The manuscript is developed through three main parts: Firstly, the French railways system is introduced and the interest in installing power electronic compensators in substations is highlighted. After a brief description of currently used solutions, the CCI concept is presented: the use of Pulse Width Modulated AC Choppers allows achieving structures which behave as variable impedances. In the second part, the use of CCI structures in reactive power compensation is investigated. The SNCF substation of Revest is under study. It is equipped by a 60MVA single phase transformer with the primary side connected to a 225kV transmission line. Based on the step-down or step-up functioning mode of CCIs, two topologies of reactive power compensator are presented. The converter design is developed on the base of a measurement campaign carried out at the substation. Numerical simulations using real current and voltage waveforms are presented. Finally, experimental results carried out at the SNCF test platform on a 1.2MVAR prototype are shown. In the last part, the problem of voltage unbalance is treated. Using the concept of CCI, the feasibility of an active Steinmetz circuit based on AC choppers is explored. As a case study, the substation of Evron is considered. It is a 32MVA substation connected to a 90kV transmission line. Measurements carried out on the substation site allow the compensator design and the possibility to consider real waveforms for current and voltage in numerical simulations. A comparison with classical solution based on two levels VSI and three levels NPC-VSI highlights the advantages of the proposed solution. Calculation and simulation results show that the stored energy in reactive elements is reduced by a factor six whereas the semiconductor losses are 40% lower. Experimental results obtained on a scaled demonstrator (1.5 kVA) validate the principle of the active Steinmetz circuit
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Besset, Pierre. "Automatic control of a marine loading arm for offshore LNG offloading offloading." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0011/document.
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Un bras de chargement de gaz est une structure articulée dans laquelle du méthane peut s’écouler à température cryogénique. En haute mer, ces bras sont installés sur le pont de navires-usines et se connectent à des méthaniers pour leur transférer du gaz. En raison de problèmes de sécurité et de performances, il est souhaité que le bras de chargement soit robotisé pour qu’il se connecte automatiquement. Cette thèse a pour objectif l‘automatisation de la connexion. Cette opération nécessite un pilotage de grande précision vis à vie de la taille du bras. Pour cette raison le bras est d’abord étalonné pour augmenter sa précision statique. Ensuite, des analyses modales expérimentales mettent en évidence l’importante souplesse de la structure des bras de chargement. Pour cette raison un générateur de trajectoires « douces », à jerk limité, est développé afin de piloter le bras sans le faire vibrer. Enfin, un système de compensation actif visant à compenser les mouvements relatifs des deux navires est mis en place. Cette compensation combine la génération de trajectoires douces avec une composante prédictive basée sur des réseaux de neurones. Cette dernière permet de prédire et d’anticiper les mouvements des navires sur l’océan, afin d’annuler tout retard dans la compensation. Finalement, cette thèse présente la première connexion automatique d’un bras de chargement, et démontre la validité de cette approcheMarine loading arms are articulated structures that transfer liquefied gas between two vessels. The flanging operation of the loading arm to the receiving tanker is very sensitive. This thesis aims to robotize a loading arm so it can flange automatically. The required accuracy for the connection is very high. A calibration procedure is thus proposed to increase the accuracy of loading arms. Moreover a jerk-limited trajectory generator is developed to smoothly drive the arm without inducing oscillation. This element is important because the structures of loading arms have a very low stiffness and easily oscillate, as highlighted by modal analyses.A predictive active compensation algorithm is developed to track without delay the relative motion between the two vessels. This algorithm relies on an artificial neural network able to predict the evolution of this relative motion. Finally this thesis presents the first automatic connection of an offshore loading arm. The success of the final tests validate the feasibility the automatic connection and the validity of this approach
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Nascimento, Bruno Moreira. "Implementação de um controle digital para o compensador regenerativo de potência ativa /." Ilha Solteira : [s.n.], 2009. http://hdl.handle.net/11449/87086.
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Orientador: Dionizio Paschoareli JuniorBanca: Falcondes Jose Mendes de Seixas
Banca: Hari Bruno Mohr
Resumo: A tendência dos sistemas de energia elétrica é uma operação cada vez mais próxima de seus limites operacionais. A presença de equipamentos que utilizam a eletrônica de potência, no controle e condicionamento da energia, é cada vez mais freqüente. A utilização de conversores como fonte de tensão, associados a elementos armazenadores de energia como, por exemplo, a bateria de sódio-enxofre, com alta densidade de energia, alta eficiência na carga e descarga e ainda um longo ciclo de vida, é a configuração básica de um Compensador Regenerativo de Potência Ativa. Compensação regenerativa de potência é um conceito que permite o armazenamento de energia em períodos favoráveis sob o ponto de vista dos custos da energia elétrica. Este conceito de compensação baseia-se no armazenamento da energia excedente ao longo do dia, nos períodos de menor tarifação, para utilizá-la nos horários de ponta (sobre-tarifa), aproveitando-se as vantagens contratuais de consumo de energia fora de ponta e promovendo-se uma melhor equalização de consumo, permitindo uma redução no contrato de demanda. Portanto, na compensação regenerativa de potência ativa, os períodos de consumo de energia são deslocados, com o objetivo de se obter redução na tarifa. Este conceito mostra-se interessante em sistemas com tarifação do tipo horo-sazonal, como é o caso brasileiro. Com o objetivo de se verificar tal troca de potência ativa, um modelo trifásico foi implementado e simulado. Os controles da potência ativa trocada entre o compensador e o sistema e da tensão na barra na qual o mesmo está instalado são realizados independentes e por controladores do tipo PID. Os sinais de controle dos interruptores semicondutores que compõe o conversor como fonte de tensão são gerados a partir do DSP TMS320F2808 da Texas Instruments, o que está embarcado no módulo didático eZdsp F2808 da Spectrum Digital
Abstract: Nowadays, electric power systems are expected to work closer to their operating limits. Power electronics based controllers, such as voltage sourced converters, are increasingly present in power systems. Electronic devices are often used to energy controlling and conditioning. The use of voltage sourced converters, associated to high-density storage elements, is the basic configuration of a Regenerative Active Power Compensator. Regenerative Active Power Compensator is a concept which proposes the energy storage as a possibility for revaluation of electrical energy cost with demand contracts. This concept is based on storing energy surplus during off peak periods, when the energy cost is cheaper, and injecting it back to the system during the overpriced peak periods. This procedure allows a better equalization of energy consumption and a reduction in electric power demand contracts. Therefore, using regenerative active power compensation, the consumption is dislocated from peak periods, resulting in a reduction of energy costs for the consumer. This concept is especially attractive for countries that use hour-seasonal fees police, as in the Brazilian case. This work proposes a three-phase model simulation with digital signal processor controller to investigate the active power flow control between the power system and the compensator, using a proportional-integral-derivative control strategy. The control signals are generate using the Texas Instruments DSP TMS320F2808, witch is embedded into the eZdsp F2808 didactic module, from Spectrum Digital
Mestre
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Black, Ross Arthur Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Compensatory strategies in humans performing active and passive gaze fixation and re-fixation tasks after unilateral vestibular deafferentation." Publisher:University of New South Wales. Graduate School of Biomedical Engineering, 2009. http://handle.unsw.edu.au/1959.4/43541.
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The human vestibulo-ocular reflex (VOR) stabilizes gaze during head movement. The reflex is typically tested in a clinic or laboratory using passive rotations or artificial stimuli which measure the amount of damage the vestibular apparatus has suffered. However, during everyday activities the vestibular system is stimulated by active, self generated head movements. Head movements are often rapid and associated with the goal of achieving either gaze-fixation or re-fixation. Patients who complain of on-going symptoms will typically identify a particular position or movement that aggravates their symptoms in their everyday life. There is a need to identify objective parameters which correlate with the subjective complaints of patients whose symptoms persist after vestibular damage. In the first study, a gaze-refixation task, patients who complain of ongoing symptoms (poorly-compensated), during rapid head turns, after unilateral vestibular de-afferentation (uVD) were compared with those who did not have the same complaints (well-compensated) and normal subjects. Well- and poorly-compensated groups were sorted according to responses on a standardized questionnaire. All subjects were then located in a real-world, non-laboratory environment in which poorly-compensated subjects reported experiencing symptoms. Each subjects head, eye and gaze displacement and velocity, head rotation frequency and blink or eye-lid closure were measured and analysed and compared between ipsi- and contra-lesional head rotations within and between subject groups. When subjects are able to generate their own active head rotations it has been suggested that a number of vestibular and extra-vestibular strategies might be employed to compensate for an impaired VOR. In subsequent studies, high resolution scleral search coils were used to identify the compensatory mechanisms used during active head rotations during a gaze-fixation task. A corrective saccade is typically observed during passive ipsilesional head rotations or impulses and might be potentiated during rapid, active or self-generated head rotations. The conditions which predict or contribute to the generation of the rapid, corrective eye movement were investigated. The results were compared with responses to passive head impulses of matched velocity and acceleration to determine if active head impulses could be used to identify a lesioned vestibular apparatus as is routinely clinically achieved with passive head impulses.
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Masuda, Mario. "Aplicação do dispositivo FACTS (Flexible AC Transmission Systems) em sistema de distribuição -simulação de desempenho." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-08122006-161400/.
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As novas tecnologias FACTS aplicadas ao sistema de transmissão, com base em eletrônica de potência, podem também ser úteis à distribuição. Para tal é preciso conduzir um procedimento de consolidação da utilização e do desempenho destas, para sua aplicação sem riscos. Neste trabalho, dois aspectos serão contemplados. O primeiro se refere à aplicação do dispositivo FACTS atuando como um capacitor série. Em se tendo controle de módulo e da fase da tensão inserida em série com a linha pode-se fazê-la comportar-se como uma queda em uma reatância série capacitiva ou indutiva. O controle dessa reatância série (aumentando/diminuindo) permitirá a aplicação do conceito de compensação série em qualquer ponto do sistema de distribuição, provendo benefícios de um controle contínuo da tensão e também do controle do fluxo de carga no sistema independente da corrente. O segundo aspecto refere-se ao uso dos dispositivos na conexão de alimentadores controlando a potência ativa entre eles. Para esta operação outro dispositivo UPFC, com conceito similar ao descrito acima, entretanto atuando na fase da tensão entre 2 barras, comporta-se como um transformador defasador com variação contínua de ?taps?, podendo controlar a potência ativa entre os alimentadores. A aplicação destas tecnologias propiciarão vários benefícios para a expansão da distribuição tais como, flexibilização do uso da rede, interligação de alimentadores permitindo manobras de blocos de energia sem ?pisca?, ajuste contínuo do suporte de reativos durante a operação, controle dinâmico do fluxo de potência. O objetivo deste trabalho é estudar a aplicabilidade da tecnologia FACTS e estender este conceito para aplicação em sistemas de distribuição e conduzir simulações digitais em redes de distribuição (15kV) identificando o desempenho e os benefícios atingidos. O programa de simulação utilizado é o ATP (Alternative Transients Program).The new FACTS technologies applied to the transmission system, based on power electronics, can also be useful to the distribution. For that, it is necessary to drive a procedure to consolidate the use and the performance for their application without risks. In this work two aspects will be approached. The first refers to the application of a FACTS device acting as series compensator. This device will be able to control the voltage in module and phase in order to act as a voltage drop in a serie reactance with capacitive or inductive features. The control of this series reactance (increasing/ decreasing) will allow the application of series compensation concept to any point of the distribution system, providing the benefits of continuous control of the voltage added to the load flow control in the system independent of the current. The second aspect refers to its use in the connection of two feeders controlling the active power between them. For this operation other device, UPFC, with similar concept as described previously, acts mainly in the phase of the injected voltage in the line, performing as a phase-shift with continuous taps variation and is able to control the active power flow between feeders. The application of this technology will provide several benefits for the distribution expansion, such as, a greater flexibility in the use of the network, connection of feeders without load flow interruption, continuous adjust of reactive power during the operation and dynamic control of power flow. The purpose of this work is to study the applicability of the FACTS technology, to extend this concept for the application in the distribution system by using digital simulations in distribution network up to 15kV identifying the performance and the reached benefits.
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Gasc, Laurent. "Conception d'un actionneur à aimants permanents à faibles ondulations de couple pour assistance de direction automobile : approches par la structure et par la commande." Phd thesis, Toulouse, INPT, 2004. http://oatao.univ-toulouse.fr/7375/1/gasc.pdf.
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Cette étude cofinancée par la société RENAULT et le CNRS porte sur la conception d'un actionneur à aimants permanents pour assistance de direction automobile. L'analyse du cahier des charges montre la nécessité d'obtenir un moteur à très faibles ondulations de couple. La réduction des ondulations de couple est traitée de deux façons : une première action consiste à concevoir la structure du moteur et une seconde à compenser les ondulations de couple par une loi de la commande adéquate. Concernant le dimensionnement du moteur, une étude du système mécanique a permis d'expliciter le lien entre la raideur du capteur de couple intégré à la colonne de direction et l'inertie du moteur ramenée au volant. Cette contrainte inertielle associée à une température ambiante élevée constituent des points forts du dimensionnement pour un encombrement donné. Il est montré que le choix d'un capteur de couple à raideur élevée permet de réduire ces contraintes de dimensionnement en réduisant la contrainte inertielle. Un modèle électromagnétique analytique et un modèle thermique couplés ont été développés et exploités suivant une méthodologie définie par la spécificité du cahier des charges. L'étude des différentes techniques de minimisation des ondulations de couple et la caractérisation électromagnétique ont été menées par calcul des champs avec FLUX2D(tm). Une solution basée sur une structure à nombre fractionnaire d'encoche par pôle et par phase et un bobinage original est proposée. La réalisation d'un prototype et les essais réalisés ont permis de valider certains aspects de ce dimensionnement. Concernant la minimisation des ondulations de couple par la commande, des modèles de simulation sous Simulink intégrant les ondulations de couple définis à partir des calculs de champs ont été développés. Différentes structures d'observateurs de couple avec prise en compte des ondulations de couple sont présentées et comparées. Une structure originale basée sur un filtre de Kalman associé à un observateur de couple de type Luenberger est mise à jour. Cette structure permet un autopilotage sans capteur de position tout en réduisant fortement les ondulations de couple. Une loi de commande par retour d'état et une structure RST associées à un observateur de couple ont été implantées sur un banc mécanique conçu et instrumenté dans le but de reproduire le fonctionnement du système de direction assistée électrique.
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Felicetti, Roberto. "Field Current Control for the Damping of Rotor Oscillations and for the Alternative Start of Synchronous Machines : Further Innovative Applications of Field Current Active Control besides UMP-Compensation." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353669.
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The possibility to save energy in synchronous machines operation by dismissing d-axis damping bars and surrogating them with active excitation current control in sectored field winding is proved. In particular a way to recover the energy of rotor oscillations during power regulation is shown by means of a studycase generator whereas a self-starting machine is analytically and numerically designed in view of its next construction and test. Principal design requirements and limits for both applications are presented and discussed.
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Aliouane, Kamel. "Contribution à l'étude du filtrage d'harmoniques des réseaux de distribution à l'aide de l'association de filtres actif et passif parallèle." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL012N.
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Cette thèse est consacrée à l'étude de l'association d'un filtre actif avec un filtre passif. Cette association peut conduire à une augmentation sensible des performances de filtrage ainsi que des potentialités d'application. Différentes structures sont envisageables, mais les deux configurations retenues (filtre actif en série avec l'alimentation ou en série avec le filtre passif) conduisent à un dimensionnement réduit du filtre actif, tout en assurant de bonnes performances de filtrage. Dans les deux cas, le filtre actif ne fonctionne pas comme un compensateur d'harmoniques. Il joue le rôle d'isolateur d'harmoniques, s'opposant en particulier aux phénomènes de résonance. C’est la raison pour laquelle il nécessite une plus faible puissance comparée à la puissance d'un filtre actif parallèle. Afin de valider l'étude effectuée, une maquette expérimentale monophasée de puissance réduite a été développée. Elle a permis de montrer que les caractéristiques de filtrage sont indépendantes de l'impédance de source et que les performances du filtre passif sont nettement améliorées
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Wang, Xuan. "Contrôle de forme d'un miroir spatial par actionneurs piézoélectriques." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0043/document.
Full textAbstract:
La prochaine génération de télescopes spatiaux devra repousser les limites des technologies actuelles afin d’accroitre les performances techniques et opérationnelles. Dans le cas d’observations difficiles, l'utilisation de plus grandes ouvertures des miroirs primaires est essentielle pour obtenir la résolution optique et la sensibilité requises. Toutefois, les grandes ouvertures primaires induisent un certain nombre de défis techniques tels que la masse, le volume et la raideur du miroir. La masse et le volume doivent rester acceptables par rapport au lanceur et la raideur du miroir, qui diminue avec l’augmentation du diamètre du miroir, doit être suffisante afin que les performances ne soient pas altérées par les déformations statiques et dynamiques. Pour surmonter ces limitations, des configurations de miroirs déformables comportant des éléments de contrôle actifs sont étudiées pour les futurs télescopes spatiaux. Les actionneurs piézoélectriques, qui répondent aux exigences de puissance massique et de bande passante, peuvent être utilisés comme éléments de contrôle actifs intégrés dans la structure de miroir. Toutefois, ces actionneurs montrent en fonctionnement en boucle ouverte des comportements non linéaires indésirables, comme le fluage et l'hystérésis, qui peuvent conduire à des inexactitudes indésirables et limiter les performances des systèmes. Par conséquent, pour les miroirs déformables activés par des actionneurs piézoélectriques, la compensation des non linéarités dans les actionneurs piézoélectriques est indispensable.La conception d’un miroir léger, compact et déformable à raideur adéquate est un défi très important pour les télescopes spatiaux mais n'est pas abordée dans cette thèse. Cette thèse porte sur le contrôle de surfaces de miroirs déformables actionnés par des actionneurs piézoélectriques et en particulier sur la compensation du fluage et de l'hystérésis dans les actionneurs piézoélectriques. La technologie de miroir actif étudié (avec des pieds activés, type miroir fakir) requiert un grand nombre d’actionneurs afin de tenir les exigences en termes de planéité de surface et ne permet pas un contrôle en boucle fermée de chaque actionneur (ce type de contrôle est trop exigeant en nombre de capteurs). La compensation du fluage et de l’hystérésis est donc réalisée en boucle ouverte et s’appuie sur des modèles précis des non linéarités à compenser et sur l’implémentation de modèles inverses. Un support d’étude expérimental a été élaboré au cours de la thèse afin de valider les études théoriques par des résultats expérimentaux. Il représente une partie d’un miroir de grande taille et consiste en une plaque de verre circulaire de diamètre 300mm dont la surface peut être actionnée par 7 actionneurs piézoélectriques annulaires.Les premières chapitres de la thèse concernent l’étude de la compensation en boucle ouverte du fluage et de l’hystérésis dans un seul actionneur qui est alors considéré comme un système SISO (single input – single output). Dans le dernier chapitre de la thèse, le fluage et de l’hystérésis sont compensés dans 3 actionneurs simultanément, ceux-ci formant un système MIMO (multi input – multi output). Les apports de la thèse concernent le développement de nouveaux modèles directs et inverses de fluage et d’hystérésis qui ont été validés par des expérimentations réalisées dans un contexte difficile de par la faible étendue des amplitudes de déplacement ( de l’ordre du micromètre)The next generation of space-based observation systems will make use of larger primary mirrors to achieve higher image resolution. Large primary mirrors lead to the increase of structural flexibility and are more susceptible to distortions. Thus maintaining optical tolerances across the mirror surface becomes increasingly difficult. The techniques of active shape control may be required for spatial mirror surfaces in future space observation systems. Piezoelectric actuators are often studied as embedded elements for the active control of mirror structures due to their excellent properties. However, unwanted nonlinear effects in piezoelectric actuators, i.e., hysteresis and creep, severely limit the service performance. This thesis aims at developing openloopcontrol laws to compensate hysteresis and creep effects in piezoelectric actuators. The studies led during this thesis are applied to the shape control of spatial mirror surfaces. An experimental setup with a small-scale mirror test structure involving multiple piezoelectric actuators is first developed and is used as support for all the measurements conducted during this thesis. Then the open-loop control methodologies of creep compensation, hysteresis compensation, and simultaneous compensation of both the nonlinear effects in a single piezoelectric actuator are respectively developed. To compensate creep, a nonlinear viscoelastic model is used to portray creep, and a new inverse model of creep based on the concept of “voltage relaxation” is proposedRegarding the hysteresis compensation, the classical Preisach model is modified by adding a derivative term in parallel to describe hysteresis more accurately with relatively few measurements, and the new inverse model is constructed in the similar way. For the simultaneous compensation of the two nonlinear effects, the hysteresis is first compensated and then, the creepof the hysteresis-compensated piezoelectric actuator is attenuated by open-loop control. The methodology is first developed for a single actuator. Finally, the shape control of a mirror surface with several piezoelectric actuators is achieved by actuating the points on the mirror surface in such a way as to reach the required displacements. The mirror test structure involving multiplepiezoelectric actuators compensated in hysteresis and creep is considered as a linear system on which the superposition principle can be applied. The influence coefficients characterizing the coupling effect between the piezoelectric actuators are determined by measurements. The influence coefficient matrix is first constructed using the superposition principle, and is then inverted. By insertion of the inverse matrix in cascade with multiple piezoelectric actuators with hysteresis and creep compensation, a feed-forward control approach to actuate the multiple interesting points of the mirror surface is developed. A number of experimental results demonstrate that the developed control methodologies are effective and feasible in practice
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Castellanos, Silva Abraham. "Compensation adaptative par feedback pour le contrôle actif de vibrations en présence d’incertitudes sur les paramètres du procédé." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT050/document.
Full textAbstract:
Dans cette thèse, nous proposons des solutions pour la conception de systèmes de contrôle actif de vibration robustes (AVC). Le manuscrit de thèse comporte deux grandes parties.Dans la première, les problèmes d'incertitude paramétrique dans les systèmes de contrôle actif de vibration sont étudiés. En plus des incertitudes sur la fréquence des perturbations, nous avons trouvé que la présence de zéros complexes peu amortis soulevait des problèmes de conception difficiles, même pour des systèmes et des modèles parfaitement connus. Dans ce contexte, nous avons proposé des solutions pour le problème linéaire. Une procédure améliorée d'identification en boucle fermée a été développée pour réduire les incertitudes dans l'identification de ces zéros. Pour traiter les incertitudes sur la perturbation, l'adaptation de la fréquence est de toute façon incontournable.La seconde partie est consacrée au développement et/ou à l'amélioration de deux algorithmes, désormais classiques, de compensation par feedback adaptatif direct, fondés sur la paramétrisation de Youla-Kučera. Le premier résulte de l'amélioration d'un précédent travail (Landau et al., 2005) ; les contributions concernent la synthèse du contrôleur central robuste et l'utilisation optionnelle de la surparamétrisation du filtre Q-FIR (réponse à temps fini) avec pour effet de minimiser l'effet « waterbed » sur la fonction de sensibilité de sortie. Le second algorithme présente une structure hybride directe/indirecte qui utilise un filtre Q-IIR (à temps de réponse infini). Les améliorations sont dues principalement au dénominateur du filtre, obtenu à partir d'une estimation de la perturbation. Cette solution permet également de simplifier la conception du contrôleur central.Les algorithmes ont été testés, comparés et validés sur un procédé réel du laboratoire Gipsa-lab, dans le cadre d'un benchmark internationalIn this thesis, solutions for the design of robust Active Vibration Control (AVC) systems are presented. The thesis report is composed of two main parts.In the first part of the thesis uncertainties issues in Active Vibration Control systems are examined. In addition of the uncertainties on the frequency of the disturbances it has been found that the presence of low damped complex zeros raise difficult design problems even if plant and models are perfectly known. Solutions for the linear control in this context have been proposed. In order to reduce the uncertainties in the identification of low complex zeros and improved closed loop identification procedure has been developed. To handle the uncertainties on the disturbance frequency adaptation has any way to be used.The second part is concerned with the further development and/or the improvement of the now classical direct adaptive feedback compensation algorithms using Youla Kucera controller parametrization. Two new solutions have been proposed in this context. The first one results from the improvement of a previous work (Landau et al., 2005). The contributions are a new robust central controller design to the optional use of over parameterization of the Q-FIR filter which aims to ensure a small waterbed effect for the output sensitivity function and therefore reducing the unwanted amplification. The second algorithm presents a mixed direct/indirect structure which uses a Q-IIR filter. The improvements are mainly the effect of the Q filter denominator, which is obtained from a disturbance identification. This solution in addition drastically simplifies the design of the central controller.The algorithms have been tested, compared and validated on an international benchmark setup available at the Control System Department of GIPSA-Lab, Grenoble, France