<h2><strong>Summary</strong></h2><p><strong> </strong>Today we are probably on a point of change for the car industry. The last century was the century of vehicles with internal combustion engines. Fossil fuels were relative cheap, easy accessible and they have a high specific energy. The pollution and dependency on oil caused the last decade an increasing demand for alternatives. Alternatives for electric power plants and for car drives. Yet the turnover to hybrids is a fact and much research is done for pure electric vehicles. Research about the control of electric motors is by that become a hot topic.</p><p>To simulate an electric vehicle drive with an induction motor, a frequency converter is needed. This combination of motor and converter led to many possible experiments. With a few experiments already done and a broad theoretical background report this thesis provides a good bundle of information to start with further experiments. The experiments can become even broader when a flywheel is added as mass inertia momentum and a DC source on the DC-link. Both elements contribute for a better simulation of an electric motor in an electric vehicle.</p><p>What is described in this theoretical report about the combination of an induction motor and converter is only the tip of the iceberg. I had too less time to begin experimenting with the flying wheel. The DC-link voltage becomes ca. 540V. From the perspective of safety I could never work alone with the DC-link. Even with a companion it was too dangerous because the equipment of the Halmstad University is not made for such dangerous voltages. That’s why this thesis contains more theoretical background and less actual practical data.</p><p><strong></strong></p> / <h2>SAMENVATTING</h2><p><em>Momenteel bevinden we ons in een tijd van omslag. Na een eeuw waarin de brandstofmotor het transportlandschap domineerde, is er nood aan een alternatief. Fossiele brandstof zorgt voor schadelijke uitlaatgassen bij verbranding en de afhankelijkheid van andere landen voor de bevoorrading van fossiele brandstof blijft altijd een risicofactor. De eerste stap in deze verandering is gezet met de ontwikkeling van hybride wagens. De toekomst zal waarschijnlijk helemaal elektrisch worden. Daarom is het onderzoek naar de controle van elektrische motoren belangrijk.</em></p><p><em>In de universiteit van Halmstad zijn er verscheidene inductiemotoren aanwezig in het elektriciteitslabo. De doelstelling was dat ik een frequentieomvormer selecteerde, bestelde en parametreerde op basis van deze motoren. Daarnaast kreeg ik de vrijheid om een elektrische wagen te simuleren. Dit zou ik doen door een vliegwiel voor de traagheid en door een batterij na te bootsen om de DC-link te voeden. Al mijn informatie moest ik bundelen in deze thesistekst zodat het eventueel een handige bundel werd voor toekomstige studenten die willen werken met de convertor.</em></p><p><em>Ik had slechts 2 maanden de tijd om dit uit te voeren, metingen te doen en een theoretisch verslag te schrijven. Vanwege deze korte tijdspanne was het niet mogelijk het vliegwiel te implementeren. Daarnaast was de tussenkringspanning ongeveer 540V DC. Dit is zeer gevaarlijk zodat ze liever hadden dat ik de proeven met een gesimuleerde batterij liet varen. Dit verklaart enigszins waarom uitgebreide meetresultaten ontbreken en deze thesis vooral een bredere theoretische toets heeft.</em></p>

Summary  Today we are probably on a point of change for the car industry. The last century was the century of vehicles with internal combustion engines. Fossil fuels were relative cheap, easy accessible and they have a high specific energy. The pollution and dependency on oil caused the last decade an increasing demand for alternatives. Alternatives for electric power plants and for car drives. Yet the turnover to hybrids is a fact and much research is done for pure electric vehicles. Research about the control of electric motors is by that become a hot topic. To simulate an electric vehicle drive with an induction motor, a frequency converter is needed. This combination of motor and converter led to many possible experiments. With a few experiments already done and a broad theoretical background report this thesis provides a good bundle of information to start with further experiments. The experiments can become even broader when a flywheel is added as mass inertia momentum and a DC source on the DC-link. Both elements contribute for a better simulation of an electric motor in an electric vehicle. What is described in this theoretical report about the combination of an induction motor and converter is only the tip of the iceberg. I had too less time to begin experimenting with the flying wheel. The DC-link voltage becomes ca. 540V. From the perspective of safety I could never work alone with the DC-link. Even with a companion it was too dangerous because the equipment of the Halmstad University is not made for such dangerous voltages. That’s why this thesis contains more theoretical background and less actual practical data. / SAMENVATTING Momenteel bevinden we ons in een tijd van omslag. Na een eeuw waarin de brandstofmotor het transportlandschap domineerde, is er nood aan een alternatief. Fossiele brandstof zorgt voor schadelijke uitlaatgassen bij verbranding en de afhankelijkheid van andere landen voor de bevoorrading van fossiele brandstof blijft altijd een risicofactor. De eerste stap in deze verandering is gezet met de ontwikkeling van hybride wagens. De toekomst zal waarschijnlijk helemaal elektrisch worden. Daarom is het onderzoek naar de controle van elektrische motoren belangrijk. In de universiteit van Halmstad zijn er verscheidene inductiemotoren aanwezig in het elektriciteitslabo. De doelstelling was dat ik een frequentieomvormer selecteerde, bestelde en parametreerde op basis van deze motoren. Daarnaast kreeg ik de vrijheid om een elektrische wagen te simuleren. Dit zou ik doen door een vliegwiel voor de traagheid en door een batterij na te bootsen om de DC-link te voeden. Al mijn informatie moest ik bundelen in deze thesistekst zodat het eventueel een handige bundel werd voor toekomstige studenten die willen werken met de convertor. Ik had slechts 2 maanden de tijd om dit uit te voeren, metingen te doen en een theoretisch verslag te schrijven. Vanwege deze korte tijdspanne was het niet mogelijk het vliegwiel te implementeren. Daarnaast was de tussenkringspanning ongeveer 540V DC. Dit is zeer gevaarlijk zodat ze liever hadden dat ik de proeven met een gesimuleerde batterij liet varen. Dit verklaart enigszins waarom uitgebreide meetresultaten ontbreken en deze thesis vooral een bredere theoretische toets heeft.

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, December 2003. / Thesis advisor(s): David C. Jenn, Jeffrey B. Knorr, Kevin Jones. Includes bibliographical references (p. 111-114). Also available online.

No description available.

This research investigates a low-cost generator and power electronics unit for smallscale (<10kW) wind turbines, for both standalone and grid-connected applications. The proposed system uses a high-inductance permanent magnet generator together with a switched-mode rectifier (SMR) to produce a variable magnitude output current. The high inductance characteristic allows the generator to operate as a current source, which has the following advantages over conventional low-inductance generator (voltage source) systems: it offers simple control, and avoids the need for bulky / costly energy storage elements, such as capacitors and inductors. The SMR duty-cycle is controlled in an open-loop manner such that 1) maximum power is obtained for wind speeds below rated, and 2) the output power and turbine speed is limited to safe values above rated wind speed. This topology also has the ability to extract power at low wind speeds, which is well suited to small-scale wind turbines, as there is often limited flexibility in their location and these commonly see low average wind speeds. The thesis is divided into two parts; the first part examines the use of the SMR as a DC-DC converter, for use in standalone applications. The duty-cycle is essentially kept constant, and is only varied for maximum power tracking and turbine speed / power limiting purposes. The SMR operates in to a fixed voltage source load, and has the ability to allow current and hence power to be drawn from the generator even at low wind and hence turbine speeds, making it ideal for battery charging applications. Initial dynamometer testing and limited wind-tunnel testing of a commercially available wind turbine show that turbine power can be maximised and its speed can be limited by adjusting the SMR duty-cycle in an open-loop manner. The second part of the thesis examines the use of the SMR as a DC-AC converter for grid-connected applications. The duty-cycle is now modulated sinusoidally at the mains frequency such that the SMR produces an output current that resembles a fullwave rectified sinewave that is synchronised to the mains voltage. An additional H-bridge inverter circuit and low-pass filter is used to unfold, filter and feed the sinusoidal output current in to the utility grid. Simulation and initial resistive load and preliminary grid-connected tests were used to prove the inverter concept, however, the permanent magnet generator current source is identified as non-ideal and causes unwanted harmonic distortion. The generator harmonics are analysed, and the system performance is compared with the Australian Standard THD requirement. It is concluded that the harmonics are caused by 1) the low-cost single-phase output design, 2) the use of an uncontrolled rectifier, and 3) the finite back-EMF voltage. The extent of these harmonics can be predicted based on the inverter operating conditions. A feed-forward current compensation control algorithm is investigated, and shown to be effective at removing the harmonics caused by the nonideal current source. In addition, the unipolar PWM switching scheme, and its harmonic components are analysed. The low-pass filter design is discussed, with an emphasis on power factor and THD grid requirements. A normalised filter design approach is used that shows how design aspects, such as cutoff frequency and quality factor, affect the filter performance. The filter design is shown to be a trade-off between the output current THD, power loss, and quality factor. The final chapter summarises the thesis with the design and simulation of a 1kW single-phase grid-connected inverter. The inverter is designed based on the low-pass filter and feed-forward compensation analysis, and is shown to deliver an output current to the utility grid that adheres to the Australian Standards. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1375316 / Thesis (Ph.D.) - University of Adelaide, School of Electrical and Electronic Engineering, 2009

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, December 2003. / "December 2003". Thesis advisor(s): David C. Jenn. Includes bibliographical references (p. 111-114). Also available online.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-11-08T17:40:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Moraes_ABNT.pdf: 5928696 bytes, checksum: ffd79ada8f98120795b81b1c40caf20d (MD5) / Made available in DSpace on 2016-11-08T17:40:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Moraes_ABNT.pdf: 5928696 bytes, checksum: ffd79ada8f98120795b81b1c40caf20d (MD5) Previous issue date: 2015-10-29 / Cnpq / Quando comparados aos retificadores tradicionais a diodo ou tiristor, os retificadores PWM têm algumas vantagens como corrente de entrada senoidal, filtro capacitivo pequeno e fator de potência controlado. No entanto, esses conversores são sensíveis a tensões desbalanceadas e transitórios de tensão. Problemas que ocorrem frequentemente em sistemas de potência trifásicos devido a cargas desbalanceadas e faltas no sistema elétrico. Sob essas condições, alguns problemas como; ripple na tensão o barramento CC e presença de harmônicos na correntes da rede podem ser evidenciados. Assim, para manter a tensão do barramento CC constante sem injetar mais correntes harmônicas na rede, surgem duas opções básicas. A primeira é a utilização de grandes filtros capacitivos para atenuar o ripple de tensão, com a possibilidade de ressonância no sistema, além do aumento dos custos e tamanho do retificador tradicional. A segunda alternativa, na qual desenvolve-se o trabalho, é a utilização de uma estratégia de controle, durante faltas no sistema. O trabalho realiza uma análise comparativa de três estratégias de controle. / When compared to traditional thyristor or diode rectifiers, the rectifiers PWM have some advantages like sinusoidal input current, small capacitive filter and power factor control. However, such converters are susceptible tensions unbalanced and transient voltage. Problems that often occur in systems three-phase power due to unbalanced loads and faults in the electrical system. Under these conditions, some problems like; ripple on the DC bus voltage and the presence of harmonic currents in the network can be evidenced. Thus, to maintain tension the constant DC bus without injecting more harmonic currents in the network, there are two basic options. The first is the use of large capacitive filters to attenuate the ripple voltage, with the possibility of resonance in the system, and increased costs and size of traditional rectifier. The second alternative, which develops in the work, is the use of a control strategy during system faults. The work carries a comparative analysis of three control strategies

O presente trabalho visa estabelecer uma metodologia alternativa para o levantamento dos principais transitórios elétricos sofridos por excitatrizes brushless, decorrentes de transitórios ocorridos na armadura do gerador principal. O método consiste no cálculo, a partir de dados de projeto, dos parâmetros que compõem os circuitos equivalentes do gerador principal e da excitatriz, seguido de simulações, em ambiente PSIM®, dos piores casos de transitórios de tensão e corrente sofridos pela armadura do gerador principal, como curtos-circuitos monofásicos, bifásicos e trifásicos, operação assíncrona do gerador principal e sincronização com defasagem entre as tensões do gerador e da rede. Em cada caso, monitoram-se as tensões e correntes resultantes nos diodos da ponte retificadora rotativa. Resultados simulados e experimentais são comparados. / This study aims to establish an alternative methodology for determining the main transients on brushless exciters due to transients in the main generator armature. The method consists in calculating, from design data, the parameters of the equivalent circuits of the main generator and the exciter, followed by simulations, with the software PSIM®, of the worst voltage and current transient cases in the main generator armature, like single-phase, dual-phase and three-phase short circuits, asynchronous running of the main generator and out of phase synchronization. In each case the currents and voltages of the rotative bridge diodes were monitored. Simulation and experimental results are compared.

Master of Science / Department of Electrical and Computer Engineering / Behrooz Mirafzal / The rise of Wide Band Gap (WBG) devices has brought excitement in the field of Power converters. The WBG based converter can operate at the very high frequency and temperature making them ideal to use in harsh environments. The commercialization of WBG devices such as SiC and GaN MOSFETs has made it interesting for power engineering professionals all over the world. The use of WBG devices capable of operating at high switching frequencies reduces the overall system size dramatically with added benefit of improved power quality at high temperature. The main goal of this thesis is to design and test an AC-DC converter based on a SiC power module. The designed rectifier can be considered an active rectifier equipped with a controller to constantly provide feedback for modification of switching signals to get the desired output voltage. The designed active rectifier converts the varying frequency input power supply into rectified DC voltage while keeping the power factor of the system to unity. This thesis covers elementary information on power supply design, switching schemes and design of the controller. System arrangement will provide more light on the use of Six Channel MOSFET Gate Driver from CREE with the overall experimental setup. The experimental analysis will summarize the behavior of the system where information on achieved rectification, effect on the line currents at the generator and concluding power factor representation is described.

A rectifier is an electrical device, comprising one or more semiconductor devices arranged for converting alternating current to direct current by blocking the negative or positive portion of the waveform. The purpose of this study would be to evaluate dynamic and static electrical characteristics of rectifier chips fabricated with (a) DY8 process and (b) YI8 process and compare them with the existing DI8 process rectifiers. These new rectifiers were tested to compare their performance to meet or exceed requirements of lower forward voltages, leakage currents, reverse recovery time, and greater sustainability at higher temperatures compared to diodes manufactured using boron as base (DI8 process diodes) for similar input variables.