O presente trabalho trata do estudo e análise da influência da saturação magnética no torque de uma máquina síncrona com ímã permanente no rotor. A máquina síncrona em es-tudo trata-se de uma máquina cuja forma de onda de força contra eletromotriz é trapezoidal. Inicialmente é feito um estudo sobre os efeitos da saturação magnética nos três principais parâmetros da máquina, indutância de fase, relutância (vista pelo circuito que tem como fonte de fluxo magnético os ímãs permanentes) e a força contra eletromotriz. Em seguida, realiza-se um estudo sobre o torque eletromagnético para a máquina e a importância dos parâmetros estudados, demonstrando a forte dependência da qualidade do torque com estes parâmetros. Com base nos estudos sobre saturação e torque, objetiva-se, portanto, descrever o comportamento de cada um dos parâmetros quando da saturação da máquina e quanto/como cada um deles afeta o torque eletromagnético da máquina. A fim de se estudar cada componente do torque separadamente, avalia-se a máquina por meio do Método da Permeabilidade Fixa. Por fim, faz-se simulações em elementos finitos empregando o método apresentado e os resultados são analisados. / This work deals with the influence of magnetic saturation on torque of permanent mag-net synchronous machine. At first, a study of magnetic saturation is carried out in order to understand its influence on three main machines parameters, phase inductance, magnet re-luctance and back electromotive force. A study describing the electric torque and its compo-nents is carried out. This study explain the importance of each machines parameter on electric torques smoothness and amplitude. In order to investigate and describe each torques com-ponent, a review on Frozen Permeability Method is developed. At last, some simulation by means of finite element method with Frozen Permeability Method are carried out. The results are shown and analyzed.

Stacked commercial second generation (2G) high temperature superconducting (HTS) tapes has been demonstrated to have great field trapping ability, with superior mechanical, thermal properties and crossed-field performance to HTS bulks. HTS stacks are considered as a very promising candidate for superconducting permanent magnets, which can be used for many applications like superconducting machines and levitation devices. However, the current magnetization methods for HTS stacks are the conventional magnetization methods developed for HTS bulks decades ago, which have various limitations. On the other hand, the recent progress on HTS flux pumping technology enables HTS coils to be successfully magnetized in an effective and efficient way. In this thesis, these two concepts were combined for the first time. Flux pumping for HTS stacks was proposed and developed as a new magnetization technique. I employed two types of flux pumps, the rotating magnet flux pump and the rectifier type flux pump, to magnetize the modified HTS stacks. The design of the flux pumps, the experimental results and the analysis of the observed behaviours are presented in the thesis. This research provides a new direction in the magnetization of HTS permanent magnets, which has the potential to make HTS permanent magnets more practical with lighter, more compact and efficient magnetization setups.

A teoria de duplo eixo é geralmente utilizada para modelar e caracterizar máquinas síncronas de polos salientes. O conhecimento das indutâncias de eixo direto e eixo em quadratura são fundamentais para o desenvolvimento destes modelos e para o projeto de controladores destas máquinas. No entanto, métodos tradicionais para determinação destas indutâncias através de ensaios tornam-se impraticáveis em máquinas síncronas de ímãs permanentes pela impossibilidade de controlar a corrente de campo. Recentemente, a IEEE publicou o Std. 1812, chamado Trial-Use Guide for Testing Permanent Magnet Machines, que pode servir de guia para obtenção da reatância de eixo direto Xd. Esta norma não sugere formas de determinar a reatância de eixo em quadratura Xq, mas existem diferentes métodos para calcular este parâmetro a partir de dados coletados em testes, geralmente envolvendo medição de ângulo de carga. O objetivo deste trabalho é propor e analisar dois métodos alternativos para determinar as reatâncias do modelo de duplo eixo através de ensaios aplicados a um gerador síncrono de ímãs permanentes (GSIP) de 1,5 kW. O primeiro é baseado em predição de ângulo de carga e o segundo é baseado em medição de ângulo de carga. O primeiro combina ensaios a vazio e de curto circuito com análise do diagrama fasorial para descrever o ângulo de carga como função de grandezas elétricas facilmente mensuráveis. O segundo propõe um método de medição de ângulo de carga com auxílio de um encoder incremental. Resultados comprovam que é possível determinar indutâncias do modelo de duplo eixo com as equações desenvolvidas desde que o conteúdo harmônico não seja elevado. / A teoria de duplo eixo é geralmente utilizada para modelar e caracterizar máquinas síncronas de polos salientes. O conhecimento das indutâncias de eixo direto e eixo em quadratura são fundamentais para o desenvolvimento destes modelos e para o projeto de controladores destas máquinas. No entanto, métodos tradicionais para determinação destas indutâncias através de ensaios tornam-se impraticáveis em máquinas síncronas de ímãs permanentes pela impossibilidade de controlar a corrente de campo. Recentemente, a IEEE publicou o Std. 1812, chamado Trial-Use Guide for Testing Permanent Magnet Machines, que pode servir de guia para obtenção da reatância de eixo direto Xd. Esta norma não sugere formas de determinar a reatância de eixo em quadratura Xq, mas existem diferentes métodos para calcular este parâmetro a partir de dados coletados em testes, geralmente envolvendo medição de ângulo de carga. O objetivo deste trabalho é propor e analisar dois métodos alternativos para determinar as reatâncias do modelo de duplo eixo através de ensaios aplicados a um gerador síncrono de ímãs permanentes (GSIP) de 1,5 kW. O primeiro é baseado em predição de ângulo de carga e o segundo é baseado em medição de ângulo de carga. O primeiro combina ensaios a vazio e de curto circuito com análise do diagrama fasorial para descrever o ângulo de carga como função de grandezas elétricas facilmente mensuráveis. O segundo propõe um método de medição de ângulo de carga com auxílio de um encoder incremental. Resultados comprovam que é possível determinar indutâncias do modelo de duplo eixo com as equações desenvolvidas desde que o conteúdo harmônico não seja elevado.

Wind energy has been the fastest emerging renewable energy source over the last decade. The overriding provisos to minimise greenhouse emissions and increasing concerns regarding energy security have been the major inducements for many countries to make a resolute transition to new and non-conventional power sources. Direct-drive systems for wind turbines are potentially a more reliable alternative to gearbox driven systems. Gearboxes are liable to significant accumulated fatigue torque loading with relatively high maintenance costs. It is with this in mind that the primary focus of this research is on direct-drive wind turbines. Generators in direct-drive wind turbines tend to be of large diameter and heavier due to the support structure required to maintain as small air-gap as possible between the stationary and rotating parts of the generator. Permanent magnet generators (PMGs) are the most common type to be used within direct-drive wind turbines nowadays. Generators and other drive-train components in wind turbines experience significant varying loads, which may lead to a bearing failure. These varying loads can lead to misalignment within the drivetrain producing eccentricity between the generator rotor and stator. Rotor eccentricity generates a magnetic force referred to as Unbalanced Magnetic Pull (UMP). The induced UMP for the same rotor eccentricity is much higher in PMGs than induction generators because of the higher permanent magnet magnetic field. UMP is an important issue requiring further research. A part of this study provides a more detailed treatment of UMP under varying rotor eccentricity regimes for various permanent magnet machine topologies. The effect of UMP in direct-drive PMGs on the lifetime of the main bearing is a topic that requires more research aimed at proposing design improvements and solutions. The hope being that the availability of such solutions can be applied to practical reductions in operating costs. In brief, identification of the root causes of failure and impacts on component lifetime remain a subject of research. Establishing analytical tools for studying the impact of UMP on component lifetime in direct drive wind turbines and identifying the prospects for air gap winding machines using single bearing configuration are the two key areas for further research. Firstly, this research aims to establish the relationship between bearing forces and different types of eccentricities and UMP in direct drive machines. It is intended to use such models for predicting bearing wear and fatigue. Secondly, this research aims to establish the analytical tools for studying static, dynamic and tilting eccentricity in air-gap winding direct drive generators. Such tools are used to increase the understanding of the dynamics of direct drive PM generators. The final step of this study is using a multi-body simulation software (SIMPACK) to initiate investigations and comparison by providing assessments of electromagnetic interaction and internal drive-train loading for four possible designs for a proposed 5MW direct-drive wind turbine in response to the loads normally seen by a wind turbine. The four designs include: (a) iron-cored PM direct-drive generator supported by two main bearings, (b) airgap winding PM direct-drive generator supported by two main bearings, (c) iron-cored PM direct-drive generator supported by a single main bearing, (d) airgap winding PM direct-drive generator supported by a single main bearing. An aero-elastic simulation code (HAWC2) is used to extract the hub loads for different wind speeds corresponding to the normal operation of the wind turbine. The dynamic eccentricity and its influence on the electromagnetic interaction and consequential effects on bearing loading for all four designs is examined to determine the most optimal support structural configuration for a direct-drive system. In summary, the main aim of this thesis is studying the effect of different types of rotor eccentricities in different types of direct drive PMGs on the main bearing arrangements. The results show that static rotor eccentricity has the maximum impact compared to the other types of eccentricities. The main result of an eccentricity is the induced UMP which applies directly as an extra force on the bearings. The influence of UMP on bearing wear is studied. This influence is found to be significant in PM machines and should be considered when designing the bearing stiffness. A 20% static rotor eccentricity in a PM machine is found to induce an UMP that roughly equals third the total weight of the machine. A single bearing design for a direct-drive wind turbine is proposed and compared with a conventional two-bearing design. The results show that the Iron-cored PM direct-drive generator supported by two main bearings design and airgap winding PM direct-drive generator supported by a single main bearing design have advantages over the other two designs in this study.

Visando analisar o comportamento de um gerador de ímãs permanentes a partir de diferentes pontos de carga aplicada, quantificando a magnetização dos ímãs presentes, desenvolveu-se um protótipo com desenho propício à adaptação para geradores eólicos. Como o objetivo é a obtenção do comportamento da magnetização dos ímãs permanentes com vários pontos de carga acoplada, optou-se pela utilização de ímãs de ferrite, com valor médio da densidade de fluxo magnético remanente (Br) igual a 0,39 T. Desta forma, o valor da carga acoplada não necessita atingir valores elevados para verificação da variação do comportamento da tensão após aplicação de carga, facilitando a avaliação de possível desmagnetização parcial ou total dos ímãs instalados. Adicionalmente é estudada divisão de carga do gerador, com tensão de saída retificada, operando em paralelo com um barramento C.C. ou banco de baterias. É apresentada uma abordagem analítica de estudo da desmagnetização dos ímãs permanentes do gerador, bem como um levantamento experimental do mesmo. Conduta semelhante é adotada no estudo da divisão de carga. / Aiming to analyze the performance of a permanent magnet generator, operating under variable load and quantifying the corresponding condition of its magnets, we have developed a prototype adaptable to wind generators. As one of the purposes of this work is to study the magnetic performance of the permanent magnets in several points of load, we have chosen ferrite magnets with average remanence (Br) of 0.39 T. Thus, even light variations in load are enough to verify the variation of the generated voltage, which eases the rating of total or partial demagnetization of the installed magnets. Additionally, we study load share of that generator, with rectified output, operating in parallel with D.C. bus or battery bank. An analytic approach of demagnetization of the generator\'s permanent magnets is also presented, as well as an experimental survey of it. A similar procedure is adopted in the study of the load share.

This dissertation addresses the design, simulation, prototype, and test of a new energy generation system, which transforms rotational motion into electricity by the use of an innovative turbine-generator. The system is divided in two assembled subsystems that interact to finally transform kinetic energy into electricity. The first subsystem is a miniaturized notched impulse turbine system, and the second one is a millimeter permanent magnet generator (PMG) assembled into the turbine. The conversion of biomechanical energy to electric energy, using clean and free energy produced by a living organism, is being increasingly researched [1]-[11]. These are all viable options, but advantages and disadvantages of each type of energy conversions should be evaluated individually to determine key factors such as efficiency as an energy harvesting method, the implementation cost, size, and the final applications where they will be used. Through this dissertation, a new option of green energy conversion is made available; focusing on the use of turbines to extract energy from microfluidics, with diverse application in biomedical, military/aerospace, and home areas. These systems have the potential of converting mechanical movement energy, and hydraulic energy into electric energy that may be sufficient for self-powering nano/micro devices and nano/micro systems. A flow, with constant pressure, a magnetic generator, and a novel impulse turbine design are combined to form a self-contained miniaturized generator system. The turbine consists of two main parts: a bearingless rotor and the enclosure or casing; while the miniaturized magnetic generator is a permanent magnet brushless machine, consisting of permanent magnets in a ring configuration and radial coils. A permanent pressure, from microfluidic pressure system, is the force used to move the blades. This rotational motion of the turbine is transformed into electricity using magnetic induction, formed by permanent magnets on the rotor and nine coils fixed in the holder of the turbine. The electricity is generated when the magnetic field rotates and moves past the conductor, which induces a current according to Faraday's Law [1-3]. The system has potential uses not only in medical equipment, but in automotive applications, home appliances, and aquatic and ventilation systems.

Sustainable energy solutions are aimed to reduce the consumption of fossil fuels by using renewable energy sources and energy efficiency techniques. This thesis presents two new sustainable energy applications in the field of electrical machines.Polyphase induction motors dominate the energy usage spectrum for industrial and commercial applications. The conventional winding structure used in both synchronous and induction machines has a basic unit of the winding with a 60 degree phase belt and a three phase connection either in star or delta. A new winding structure using an innovative Star-Delta Series Connection (SDSC) which has a high winding coefficient and low harmonic content is presented in this thesis. The principle of the SDSC winding is described. The Electro-Magnetic Belt and Electro-Magnetic Space diagram are two important means to be used for optimization of the new winding. Experimental results from two prototypes confirm the theoretical analysis. The efficiency of the new machine at rated load increased by about 3.8% as compared to the standard machine with a conventional winding structure.Wind energy is one of the most attractive renewable energy options. Wind turbines are designed to couple either synchronous or asynchronous generators with various forms of direct or indirect connection with grid or diesel generators. Permanent magnet (PM) generators using high energy Neodymium- Iron-Boron magnets offer advantages such as direct coupling without gear box, absence of excitation winding and slip rings, light weight and smaller size. This thesis presents the design and development of an outer-rotor PM generator suitable for wind energy conversion. The initial electromagnetic design followed by a Finite Element Analysis is presented in detail. A 20 kW prototype machine was built and extensively tested. It was found that the machine could maintain an ++ / efficiency of about 85% for a wide operating range. Equivalent circuit models were developed. The results of the Finite Element analysis matches closely with the experimental and the designed values.

Fault tolerant motor drives are becoming more important in safety critical applications. Although a single motor module fault tolerant drive may be sufficient in some applications, this motor drive only offers limited redundancy. This thesis investigated the dual motor module fault tolerant drive system in which two motor modules were connected electrically in phase and on a common shaft provide redundancy and to increase the reliability of the entire drive system. A general phase current mathematical model to produce the desired output torque was developed to minimize copper loss and torque ripple in the motor drive, which is applicable to both sinusoidal and trapezoidal brushless permanent magnet motor types. A detailed fault effect investigation was performed in this thesis and it is concluded that switch short-circuit fault is the most serious fault since it reduces the electromagnetic torque output significantly and generates larger torque ripple in the motor drive due to the presence of large drag torque. Three fault remedial strategies were proposed to compensate the torque loss and to reduce the torque ripple under different faulty conditions. It is concluded from the analytical results that fault remedial strategy 3 is the tradeoff algorithm in which the zero torque ripple factor can be achieved with only a modest increase in copper loss comparing with the minimum possible value. Two practical dual motor module fault tolerant brushless permanent magnet drive test arrangements with different motor structures were developed in this thesis. The computer simulation studies using the MATLAB Simulink were performed to verify the effectiveness of the proposed fault remedial strategies. The efficiency of the motor drive was predicted based on torque loss measurements and the results were verified in the simulation study. The effect of faults on the drive efficiency was investigated as well. The entire fault tolerant motor drive control system was also developed to verify the analytical and simulation results. A fault detection and identification method to detect switch open-circuit faults, switch short-circuit faults, and the winding short-circuit faults was also proposed. Its advantages are the simplicity of the implementation and reduction of the cost of the drive system. The experimental results demonstrated that the proposed fault remedial strategies can be implemented in real time motor control and are effective to compensate the torque loss and reduce the torque ripple. / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008

<p><p>A permanent magnet synchronous motor is traditionally controlled from measured</p><p>values of the angular velocity and position of the rotor. However, there is a wish</p><p>from SAAB Avitronics to investigate the possibility of estimating this angular</p><p>velocity and position from the current measurements. The rotating rotor will</p><p>affect the currents in the motor’s stator depending on the rotor’s angular velocity,</p><p>and the observer estimates the angular velocity and angular position from this</p><p>effect.</p><p>There are several methods proposed in the article database IEEE Xplore to</p><p>observe this angular velocity and angular position. The methods of observation</p><p>chosen for study in this thesis are the extended Kalman filter and a phase locked</p><p>loop algorithm based on the back electro motive force augmented by an injection</p><p>method at low velocities.</p><p>The extended Kalman filter was also programmed to be run on a digital signal</p><p>processor in SAAB Avitronics’ developing hardware. The extended Kalman filter</p><p>performs well in simulations and shows promise in hardware implementation. The</p><p>algorithm for hardware implementation suffers from poor resolution in calculations</p><p>involving the covariance matrices of the Kalman filter due to the use of 16-bit</p><p>integers, yielding an observer that only functions in certain conditions.</p><p>As simulations with 32-bit integer algorithm performs well it is likely that a 32-</p><p>bit implementation of the extended Kalman filter would perform well on a motor,</p><p>making sensorless control possible in a wide range of operations.</p></p>

The EEC (Electron Energy Corporation) in conjunction with the National Aeronautics and Space Administration is researching the magnetic bearings for an alternative to conventional journal or ball bearings. The purpose of this research was to design and develop a high-temperature (1000ºF) hybrid Magnetic Bearing using High Temperature Permanent Magnets (HTPM), developed by the EEC for high performance jet engines at high speeds that supply loads of 500 lbf. Another objective is to design and build a test rig fixture to measure the load capacity of the designed bearing. The permanent magnet bias of the Homopolar radial magnetic bearing reduces the amount of current required for magnetic bearing operation. This reduces the power loss due to the coil current resistance and improves the system efficiency because the magnetic field of the HTPM can suspend the major portion of the static load on bearing. A high temperature radial magnetic bearing was designed via an iterative search employing 3D finite element based electromagnetic field simulations. The bearing was designed to produce 500 lbf of force at 1000ºF and the design weight is 48 lbs. The bias flux of the Homopolar radial bearing is produced by EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed to measure actual load capacity of the designed bearing at the test rig. All the results obtained from the experiment were compiled and analyzed to determine the relation between bearing force, applied current and temperature.