517 research outputs found

    Book of Abstracts:9th International Conference on Smart Energy Systems

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    Dead-time impact on the harmonic distortion and conversion efficiency in a three-phase five-level Cascaded H-Bridge inverter: mathematical formulation and experimental analysis

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    To avoid leg short-circuit in inverters, dead time must be introduced on leg gate signals. Dead time affects the inverter output voltage fundamental harmonic amplitude, voltage harmonic distortion and inverter efficiency by introducing additional voltage drops. In this regard, dead time effects have been widely investigated for traditional two-level three-phase voltage source inverters in the literature but not extensively for multilevel topology structures. This paper provides a detailed analysis of dead time impact on the harmonic distortion and efficiency of Cascaded H-Bridges Multilevel Inverters (CHBMIs). For this purpose, a general mathematical formulation to determine voltage drop due to dead time effects, also taking into account the adopted Multicarrier PWM strategy, has been provided and experimentally validated for a five-level three-phase CHBMI structure. As a comparison tool between expected and ideal inverter output voltage, the percentage voltage error e% is introduced. In most of the cases, e% is lower than 5%, and it starts increasing for very low amplitude modulation index or for specific working points where nonlinearities occur. Furthermore, several experimental investigations have been carried out to evaluate the CHBMI performance in terms of harmonic distortion and efficiency by changing, the values of dead time, modulation index and switching frequency for ten different multi-carried PWM strategies. Experimental results confirm the strong dependency between the dead time impact on the converter performance and the adopted Multi Carrier-PWM (MC-PWM) strategy: as a way of example, converter efficiency can be reduced from 80% to 60% when dead time is increased from 0.5 μs to 1.5 μs and Phase Shifted-PWM (PS-PWM) is adopted

    A High-Power Medium-Voltage Open-Loop Induction Motor Drive for Industry Applications: Stability Analysis and Implementation

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    Due to their several advantages, induction motors are widely used for industrial applications today. The present study focuses on developing a robust high-power induction motor variable frequency drive. In order to test the algorithms of the motor control on an actual induction motor, it is important to first carry out simulation tests to verify and troubleshoot the control strategy. One of the most common software used for such a need is MATLAB/Simulink. To run such experiments requires a significant simulation time and at the same time must satisfy a certain level of accuracy. Therefore, one of the objectives of the thesis is to carry out a study on some of the ODE solvers of MATLAB/Simulink to choose the most efficient solver for the simulation tests of the motor control strategy. The fixed step solvers ode1, ode2 and ode4 and the variable step solvers ode45, ode113 and ode23 are studied in terms of the actual time taken to complete the simulations and the relative tolerance of each solver. Comparing the performance of the fixed step and variable step solvers it is evident that the variable step solvers outperformed the fixed step solvers in terms of both speed and accuracy. One of the most famous speed control strategies is the open loop V/Hz control. In this control method two modulation techniques were studied. This was the asynchronous modulation technique and the synchronous modulation technique. With the use of the asynchronous modulation technique subharmonics are introduced. To avoid the introduction of such harmful subharmonics the synchronous modulation technique is proposed. The synchronous modulation technique is implemented with the open loop V/Hz control strategy and simulation tests were carried out to verify the problem of subharmonics being removed. Another problem encountered with the open loop V/Hz control strategy is the presence of large current and torque oscillations of the motor at low to medium frequencies. This is due to the nonlinear interactions between the electrical and mechanical subsystems. To mitigate these unwanted oscillations a stability analysis of the open loop V/Hz control is carried out and a region of instability is determined. Two mitigation techniques are proposed in this thesis namely varying slope V/Hz control strategy and the active damping control strategy. The proposed techniques are verified and validated through simulation tests on a 7 MW medium voltage (MV) induction motor in MATLAB/Simulink and on a low voltage (LV) induction motor in laboratory without a mechanical load. Moreover, in this thesis it has been examined that with the consideration of the magnetic saturation of the motor, more stable operations are achieved. This is firstly verified in simulation where considering the magnetic saturation allowed the use of higher flux values providing more stable machine operations while at the same time allowing for a larger torque. With the experimental test on a 10-kW induction motor it was proved that the results obtained through simulations where more stable operations were seen as the value of the flux were increased were correct. In the power applications such as the ac-dc conversion for the above mentioned 7 MW medium voltage induction motor, a high total harmonic distortion (THD) can be seen in the primary currents with the use of the conventional diode-based ac-dc conversion. In addition, such a conversion does not permit the control of the dc link voltage and has not power factor correction. To overcome these shortcomings the Active Front End rectifier which uses IGBTs that can be electronically controlled is used. In the AFE, the waveform of the input current is monitored and is shaped to be sinusoidal as a result decreasing the THD. Another significant advantage of the AFE rectifier is its capability to handle regenerative power. In this thesis, two configurations of the AFE rectifier are studied. These two configurations include firstly the development of the AFE rectifier using a two-level three-phase inverter and secondly the development of the AFE rectifier with single phase H-bridge cells. From the comparison of the performance of the two configurations of the AFE it is seen that the AFE realised with the H Bridge cells and phase shifted secondary was the best in terms of the THD and the dc link voltage ripple. From these results the AFE realised with H Bridge circuits and phase shifted secondary is chosen for the operation of a real high-power induction motor controlled with the open loop V/Hz control strategy and equipped with the active damping technique for mitigating the current and torque oscillations

    Onduleur quasi-Z-source pour un système de traction de véhicules électriques à sources multiples : contrôle et gestion

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    Abstract: Power electronics play a fundamental role and help to achieve the new goals of the automobiles in terms of energy economy and environment. The power electronic converters are the key elements which interface their power sources to the drivetrain of the electric vehicle (EV). They contribute to obtaining high efficiency and performance in power systems. However, traditional inverters such as voltage-source, current-source inverters and conventional two-stage inverters present some conceptual limitations. Consequently, many research efforts have been focused on developing new power electronic converters suitable for EVs application. In order to develop and enhance the performance of commercial multiple sources EV, this dissertation aims to select and to control the impedance source inverter and to provide management approaches for multiple sources EV traction system. A concise review of the main existing topologies of impedance source inverters has been presented. That enables to select QZSI (quasi-Z-source inverter) topology as promising architectures with better performance and reliability. The comparative study between the bidirectional conventional two-stage inverter and QZSI for EV applications has been presented. Furthermore, comparative study between different powertrain topologies regarding batteries aging index factors for an off-road EV has been explored. These studies permit to prove that QZSI topology represents a good candidate to be used in multi-source EV system. For improving the performance of QZSI applied to EVs, optimized fractional order PI (FOPI) controllers for QZSI is designed with the ant colony optimization algorithm (ACO-NM) to obtain more suitable aging performance index values for the battery. Moreover, this thesis proposes a hybrid energy storage system (HESS) for EVs to allow an efficient energy use of the battery for a longer distance coverage. Optimized FOPI controller and the finite control set model predictive controller (FCS-MPC) for HESS using bidirectional QZSI is applied for the multi-source EV. The flux-weakening controller has been designed to provide a correct operation with the maximum available torque at any speed within current and voltage limits. Simulation investigations are performed to verify the topologies studied and the efficacity of the proposed controller structure with the bidirectional QZSI. Furthermore, Opal-RT-based real-time simulation has been implemented to validate the effectiveness of the proposed HESS control strategy. The results confirm the EV performance enhancement with the addition of supercapacitors using the proposed control configuration, allowing the efficient use of battery energy with the reduction of root-mean-square value, the mean value, and the standard deviation by 57%, 59%, and 27%, respectively, of battery current compared to the battery-only based inverter.L'électronique de puissance joue un rôle fondamental et contribue à atteindre les nouveaux objectifs de l'automobile en termes d'économie d'énergie et d'environnement. Les convertisseurs d’électroniques de puissance sont considérés comme les éléments clés qui interfacent leurs sources d'alimentation avec la chaîne de traction du véhicule électrique (VE). Ils contribuent à obtenir une efficacité et des performances élevées dans les systèmes électriques. Cependant, les onduleurs traditionnels tels que les onduleurs à source de tension, les onduleurs à source de courant et les onduleurs conventionnels à deux étages qui constituent les onduleurs les plus couramment utilisés, présentent certaines limitations conceptuelles. Par conséquent, de nombreux efforts de recherche se sont concentrés sur le développement de nouveaux convertisseurs d’électroniques de puissance adaptés à l'application aux véhicules électriques. Afin de développer et d'améliorer les performances des VEs à sources multiples commerciales, cette thèse vise à sélectionner, contrôler l'onduleur à source impédante et fournit une approche de gestion pour l'application du système de traction du VE à sources multiples. Une revue concise des principales topologies existantes d'onduleur à source impédante a été présentée. Cela a permis de sélectionner la topologie de l’onduleur quasi-Z-source (QZS) comme architectures prometteuses pouvant être utilisées dans les véhicules électriques, avec de meilleures performances et de fiabilité. L'étude comparative entre l'onduleur bidirectionnel conventionnel à deux étages et de celui à QZS pour les applications du VE a été présentée. En outre, une étude comparative entre différentes topologies de groupes motopropulseurs concernant les facteurs d'indice de vieillissement des batteries pour une application du VE hors route a été explorée. Ces études ont permis de prouver que la topologie de l’onduleur QZS représente une bonne topologie candidate à utiliser dans un système de VE à sources multiples. Pour améliorer les performances de l’onduleur QZS appliquées aux véhicules électriques, des contrôleurs PI d'ordre fractionnaire (PIOF) optimisés pour l’onduleur QZS sont conçus avec l'algorithme de colonies de fourmis afin d'obtenir des valeurs d'indice de performance de vieillissement plus appropriées pour la batterie. De plus, cette thèse propose un système de stockage d'énergie hybride (SSEH) pour le VE afin de permettre une utilisation efficace de l'énergie de la batterie pour une couverture de distance plus longue et une extension de son autonomie. L’optimisation du contrôleur PIOF et du contrôleur par modèle prédictif d'ensemble de contrôle fini (CMP-ECF) pour l’onduleur QZS bidirectionnel a été appliqué au VE à sources multiples avec des approches de gestion appuyées par des règles. Le contrôleur d'affaiblissement de flux magnétique du moteur a été conçu pour fournir un fonctionnement correct avec le couple maximal disponible à n'importe quelle vitesse dans les limites de courant et de tension. Des investigations et des simulations sont effectuées pour vérifier les différentes topologies étudiées et l'efficacité de la structure de contrôleur proposée avec l’onduleur QZS bidirectionnel. De plus, une simulation en temps réel basée sur Opal-RT a été mise en œuvre pour valider l'efficacité de la stratégie de contrôle SSEH proposée. Les résultats confirment l'amélioration des performances du VE avec l'ajout d'un supercondensateur utilisant la configuration du contrôle proposée, permettant une utilisation efficace de l'énergie de la batterie avec une réduction de la valeur moyenne quadratique, de la valeur moyenne et de l'écart type de 57%, 59% et 27%, respectivement, du courant de la batterie par rapport à l'onduleur connecté directement à la batterie

    Efficiency and Sustainability of the Distributed Renewable Hybrid Power Systems Based on the Energy Internet, Blockchain Technology and Smart Contracts-Volume II

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    The climate changes that are becoming visible today are a challenge for the global research community. In this context, renewable energy sources, fuel cell systems, and other energy generating sources must be optimally combined and connected to the grid system using advanced energy transaction methods. As this reprint presents the latest solutions in the implementation of fuel cell and renewable energy in mobile and stationary applications, such as hybrid and microgrid power systems based on the Energy Internet, Blockchain technology, and smart contracts, we hope that they will be of interest to readers working in the related fields mentioned above

    University of Windsor Undergraduate Calendar 2023 Spring

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    https://scholar.uwindsor.ca/universitywindsorundergraduatecalendars/1023/thumbnail.jp

    Naval Postgraduate School Academic Catalog - February 2023

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    Smart power conditioners for electric railway power grids

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    Programa doutoral em Engenharia Eletrónica e de Computadores (especialidade de Eletrónica de Potência e Energia)Railway transport presents itself as one of the greatest economic and social drivers of several nations in the world. Furthermore, it is considered the safest means of land transport, with the electric rail system being efficient and environmentally friendly. However, for the inclusion of more and larger electric locomotives, it is necessary to increase the capacity of the railway supply systems. This doctoral thesis intends to contribute to the development of power electronics solutions capable of increasing the capacity of railway supply systems. As such, a power electronics converter connected in a neutral section located between two traction power substations (TPS) is proposed. The proposed algorithm makes it possible to dynamically balance the average active powers of the two substations, mitigating overload problems. In the event of deceleration or braking of a locomotive on one side, it is possible to use the energy from this regenerative braking to assist another locomotive on the other side of the neutral section. Moreover, the proposed solution still presents the interface with a photovoltaic solar system and an energy storage system. In this way, it is possible to minimize energy dependence on the power grid, as well as to include renewable energy sources. The storage system also makes it possible to store surplus production or energy from regenerative braking for later use. The proposed solution is validated with the help of computer simulations considering a real implementation scale. The simulation model is based on cascaded multilevel modular converters, with each submodule also featuring solid-state transformers. Considering a reduced-scale prototype developed in the laboratory, computer simulations of the prototype are also presented and discussed. The document also presents a chapter that portrays all the steps taken for the implementation of the reduced-scale sectioning post-Rail Power Conditioner (sp-RPC) laboratory prototype. Once its implementation was completed, its experimental validation was carried out, proving the correct functioning of the system based on the proposed algorithm.O transporte ferroviário apresenta-se como um dos maiores impulsionadores económicos e sociais de várias nações do mundo. Para além disso, é considerado como o meio de transporte terrestre mais seguro, sendo o sistema ferroviário elétrico eficiente e amigo do ambiente. Contudo, para a inclusão de mais e maiores locomotivas elétricas é necessário aumentar a capacidade dos sistemas de alimentação ferroviários. Esta tese de doutoramento pretende contribuir com o desenvolvimento de soluções de eletrónica de potência capazes de aumentar a capacidade dos sistemas de alimentação ferroviários. Como tal, é proposto um conversor de eletrónica de potência conectado numa secção neutra que se encontra entre duas subestações de tração de energia. A algoritmia proposta permite equilibrar as potências ativas médias das duas subestações de forma dinâmica, mitigando os problemas de sobrecarga. Na ocorrência de uma desaceleração ou travagem de uma locomotiva num dos lados, é possível utilizar a energia proveniente desta travagem regenerativa para o auxílio de marcha de outra locomotiva existente no outro lado da secção neutra. Não obstante, a solução proposta apresenta ainda a interface com um sistema solar fotovoltaico e um sistema de armazenamento de energia. Desta forma, é possível minimizar a dependência energética da rede elétrica, bem como incluir fontes de energia renovável. O sistema de armazenamento permite ainda armazenar o excedente de produção ou a energia proveniente de uma travagem regenerativa para posterior utilização. O conceito proposto é estudado com auxílio de simulações computacionais considerando uma escala de implementação real. O modelo de simulação é baseado em conversores modulares multinível em cascata, sendo que cada sub-módulo apresenta ainda transformadores de estado sólido. Considerando um protótipo de pequena escala desenvolvido em laboratório, simulações computacionais do protótipo são igualmente apresentadas e validadas. O documento apresenta ainda um capítulo que retrata todos os passos realizados para a implementação do protótipo laboratorial do sectioning post-Rail Power Conditioner (sp-RPC) de pequena escala. Uma vez finalizada a sua implementação, procedeu-se à sua validação experimental, comprovando o correto funcionamento do sistema com base na algoritmia proposta.This work has been supported by FCT — Fundação para a Ciência e Tecnologia, within the R&D Units Project Scope UIDB/00319/2020. Mr. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018, granted by the Portuguese FCT foundation

    Design Approaches to Enhance Power Density in Power Converters for Traction Applications

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    This dissertation presents a design strategy to increase the power density for automotive Power Conversion Units (PCUs) consisting of DC-DC and DC-AC stages. The strategy significantly improves the volumetric power density, as evident by a proposed PCU constructed and tested having 55.6 kW/L, representing an 11.2 % improvement on the Department of Energy’s 2025 goal of 50 kW/L for the same power electronics architecture. The dissertation begins with a custom magnetic design procedure, based on optimization of a predetermined C-core geometrical relationship and custom Litz wire. It accounts for electrical and thermal tradeoffs to produce a magnetic structure to best accomplish volume and thermal constraints. This work is coupled with a control strategy for the DC-DC converter whereby a variable-frequency Discontinuous Conduction Mode (DCM) control is used to further reduce the required values of the passive components, to provide an increase in power density and a large improvement of low-power-level efficiency, experimentally demonstrated at full power through an 80 kW Interleaved Boost Converter. Integration of this enhanced DC-DC stage to the DC-AC stage requires a DC-Link capacitor, which hinders achieving power density targets. Increasing the switching frequency is an established method of reducing the size of passives. However, it is the RMS current sizing requirements that diminishes any gains achieved by raising the switching frequency. A synchronous carrier phase shift-based control algorithm, that aligns the output current of the boost stage with the input current of an inverter, is proposed to reduce the RMS current in the DC-Link capacitor by up to 25% and an average 20% smaller capacitor volume. Lastly, a new electrothermal platform based on paralleled discrete devices is presented for a 50 kW traction inverter. Embedded capacitors within the vacant volume of the hybrid material thermal management structure enables higher power density (155 kW/L) and significantly reduces cost

    ATHENA Research Book, Volume 2

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    ATHENA European University is an association of nine higher education institutions with the mission of promoting excellence in research and innovation by enabling international cooperation. The acronym ATHENA stands for Association of Advanced Technologies in Higher Education. Partner institutions are from France, Germany, Greece, Italy, Lithuania, Portugal and Slovenia: University of Orléans, University of Siegen, Hellenic Mediterranean University, Niccolò Cusano University, Vilnius Gediminas Technical University, Polytechnic Institute of Porto and University of Maribor. In 2022, two institutions joined the alliance: the Maria Curie-Skłodowska University from Poland and the University of Vigo from Spain. Also in 2022, an institution from Austria joined the alliance as an associate member: Carinthia University of Applied Sciences. This research book presents a selection of the research activities of ATHENA University's partners. It contains an overview of the research activities of individual members, a selection of the most important bibliographic works of members, peer-reviewed student theses, a descriptive list of ATHENA lectures and reports from individual working sections of the ATHENA project. The ATHENA Research Book provides a platform that encourages collaborative and interdisciplinary research projects by advanced and early career researchers
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