Tesi sul tema "Rotating electrical machines"
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1
Hargreaves, Philip Alexander. "Advanced performance prediction tools for the analysis of rotating electrical machines". Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2853.
Abstract (sommario):
This thesis seeks to advance the design tools for electrical generators. It aims to undertake an electrical generator’s design, using the Finite Element method within a defined time frame. The thesis looks at the history of generator design systems and outlines the parameters a designer must predict. These parameters are then duly calculated using various finite element methods. The thesis introduces a Pseudo Rotating Superposition system, which allows large quantities of data to be found from single static finite element simulations. Initially the system is used to predict machine saturation curves, and it is later expanded to predict the transient performance of generators. The full load performance of generators is found using a novel multivariable clustered optimisation routine. An extension using a rotating finite element solver, with pseudo rotating superposition, is then demonstrated. This creates a method which allows voltage harmonics to be quickly, accurately and validly predicted. Finally a study of iron loss is undertaken and using the above method it is shown that iron loss can be validly calculated using the quicker Radial/Tangential reference frame, rather than a slower Major/Minor frame. A collection of 48 manufactured machines are used throughout as a test group for the created methods. Results from design calculations are compared to both factory test results and to the predictions from an existing customised in house design software tool. The methods within this thesis are shown to be over 35% more accurate in the majority of cases. The whole suite of methods created can automatically calculate results for any given machine in less than 1 hour. The computer macros described in this thesis and the comparison with existing design methods and test were all made by the Author.
2
Husain, Tausif. "Rotating Reference Frame Control of Switched Reluctance Machines". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1375286539.
3
Chong, Yew Chuan. "Thermal analysis and air flow modelling of electrical machines". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10466.
Abstract (sommario):
Thermal analysis is an important topic that can affect the electrical machine performance, reliability, lifetime and efficiency. In order to predict the electrical machine thermal performance accurately, thermal analysis of electrical machines must include fluid flow modelling. One of the technologies which may be used to estimate the flow distribution and pressure losses in throughflow ventilated machines is flow network analysis, but suitable correlations that can be used to estimate the pressure losses in rotor ducts due to fluid shock is not available. The aim of this work is to investigate how the rotation affects the pressure losses in rotor ducts by performing a dimensional analysis. Apart from the additional friction loss due to the effects of rotation, other rotational pressure losses that appear in a rotor-stator system are: duct entrance loss due to fluid shock and combining flow loss at the exit of the rotor-stator gap. These losses are analysed using computational fluid dynamics (CFD) methods. The CFD simulations use the Reynolds-averaged Navier Stokes (RANS) approach. An experimental test rig is built to validate the CFD findings. The investigation showed that the CFD results are consistent with the experimental results and the rotational pressure losses correlate well with the rotation ratio (a dimensionless parameter). It shows that the rotational pressure loss generally increases with the increase in the rotation ratio. At certain operating conditions, the rotational pressure loss can contribute over 50 % of the total system loss. The investigation leads to an original set of correlations for the pressure losses in air ducts in the rotor due to fluid shock which are more suitable to be applied to fluid flow modelling of throughflow ventilated machines. Such correlations provide a significant contribution to the field of thermal modelling of electrical machines. They are incorporated into the air flow modelling tool that has been programmed in Portunus by the present author. The modelling tool can be integrated with the existing thermal modelling method, lumped-parameter thermal network (LPTN) to form a complete analytical thermal-fluid modelling method.
4
Chapariha, Mehrdad. "Modeling alternating current rotating electrical machines using constant-parameter RL-branch interfacing circuits". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45565.
Abstract (sommario):
Transient simulation programs are used extensively for modeling and simulation of various electrical power and energy systems that include rotating alternating current machines as generators and motors. In simulation programs, traditionally, the machine models are expressed in qd-coordinates (rotational reference frame) and transformed variables, and the power networks are modeled in abc-phase coordinates (physical variables), which represents an interfacing problem. It has been shown in the literature that the method of interfacing machine models and the electric network models plays an important role in numerical accuracy and computational performance of the overall simulation.
This research considers the state-variable-based simulation programs and proposes a unified constant-parameter decoupled RL-branch circuit in abc-phase coordinates (with optional zero-sequence). The proposed circuits are based on voltage-behind-reactance (VBR) formulation and can be used for interfacing both induction and synchronous machine models. The new models achieve a direct and explicit interface with arbitrary external electrical networks, which results in many computational advantages. Extensive computer studies are presented to verify the proposed models and to demonstrate their implementation in several commonly-used simulation programs. The new models are shown to offer significant improvements in accuracy and numerical efficiency over the existing state-of-the-art models due to their direct interface. It is further envisioned that the proposed models will receive a wide acceptance in research community and simulation software industry, and may enable the next generation of power systems simulation tools.
5
OLIVO, MATTEO. "Efficient Methods for the Study of Eddy-Currents Effects in Medium-Voltage Rotating Electrical Machines". Doctoral thesis, Università degli Studi di Trieste, 2020. http://hdl.handle.net/11368/2960316.
Abstract (sommario):
Lo scopo di questa tesi è presentare alcuni metodi efficienti (dal punto di vista computazionale) per il calcolo degli effetti dovuti alle correnti parassite (eddy currents) in macchine elettriche rotanti in media tensione. Due applicazioni in particolare sono state considerate nel dettaglio.
Inizialmente viene analizzato il fenomeno delle correnti parassite indotte nell'albero di motori asincroni a due poli e il conseguente effetto sulle prestazioni della macchina, focalizzandosi in particolare sul fattore di potenza. La seconda parte della tesi concentra la sua attenzione sullo studio dell'avviamento da rete di motori sincroni con rotore massiccio.
Per ciascuna applicazione vengono introdotte alcune procedure di calcolo, facenti uso di opportuni modelli numerici basati sul metodo degli elementi finiti, per mezzo delle quali vengono adeguatamente calcolati i parametri dei circuiti equivalenti di macchina, tenendo conto degli effetti legati alle correnti parassite. I modelli numerici sono opportunamente definiti, in modo tale da ridurre al massimo la complessità delle geometrie e il conseguente onere computazionale.
I risultati delle procedure innovative qui proposte sono confrontati con i dati provenienti da prove sperimentali sulle macchine oggetto di studio e con analoghi risultati di calcolo dedotti tramite le procedure comunemente utilizzate. Il confronto fra questi dati ha dimostrato che gli approcci di calcolo introdotti in questa tesi permettono di ottenere risultati con un elevato livello di accuratezza e una netta riduzione dell'onere computazionale.The efficient computation of eddy-current effects in medium voltage electric machines is discussed in this dissertation. Two particular cases are considered. Firstly, the effects of shaft eddy-currents on two-pole induction motor performance is addressed, with special focus on the power factor. In the second part of the thesis the start-up calculation of a large synchronous motor with solid rotor is analyzed. For each application a special calculation procedure is introduced. These procedures adopt a set of suitable finite-element models to properly compute the machine equivalent circuit parameters that are mainly influenced by eddy-current-related phenomena. By suitably choosing finite-element models boundary conditions and excitations their geometry is simplified to the maximum possible extent, in order to reduce the computational burden. The results of the new calculation methods are compared with experimental data and with analogous results obtained from commonly-adopted calculation procedures. The comparison proves that the proposed approaches can lead to high accuracy levels with very remarkable computational savings.
6
Carraro, Enrico. "Analysis and design procedures of permanent magnet machines for hybrid electric vehicles and rail-traction applications". Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3421927.
Abstract (sommario):
The interest for Permanent Magnet (PM) synchronous machines has increased in the recent years. This is mainly due to important developments in the field of the electrical machine design, control systems and PM technology. These factors enable the possibility of designing electrical machines with a high torque density, power density, efficiency, low cost with wide degrees of freedom. Such requirements are highly sought in the automotive field, especially following the increasingly stringent energy efficiency and air pollution emissions policies. These conditions are pushing forward the transition from the conventional internal combustion engine mobility systems to the hybrid electric and full electric vehicles for the mass market production.
Moreover, further requirements, especially in high demanding traction and auxiliary machines, such as Electric Power Steering (EPS) motors, are nowadays getting more and more important. Flux weakening performance, torque quality (cogging torque and torque ripple), demagnetization, acoustic performance and robustness of the designs has to be taken into account, together with stringent dimensional, electrical and thermal constraints typical for compact integrated automotive electrical drives.
Due to recent sky-rocketing price, instability, critical availability of Rare Earth (RE) metals and the related environmental issue for their sourcing, Heavy (HR) RE free, RE-free and even PM free machines are hunted for in the automotive market. The novel PM motor topologies meet such a „market pull“.
The main research subject of this PhD is the development of novel analysis and design procedures of PM synchronous machines for automotive applications. The latter range from low torque / power auxiliary systems, i.e. EPS machines, to high torque / high power applications, such as traction machines. It provides a comprehensive evaluation of various synchronous machine topologies. Particular attention is devoted to the study of HRE-free solutions and the development of Finite Element Analysis (FEA) and analytical procedures for the optimization of the motor designs. As mentioned above, these methodologies take into account several electromechanical constraints and various performance targets.
As regards the traction machines, the investigation is focused to the permanent magnet assisted reluctance (PMASR) topology. The interest around the PMASR motors has grown in the last years especially as consequence of the price crisis of rare earth magnets. In fact these machines represent a potential low cost replacement of conventional PM machines due to several technical advantages, such as wide speed range, competitive torque density and efficiency, high overload capability and robust structure. On the other had, the most important drawback is represented by the high torque ripple.
In the area of the electric power steering motors, several topologies, both with isotropic anisotropic rotor structures and equipped with fractional slot concentrated windings, are evaluated. Some novel motor designs, which employ the reluctance and flux concentration principle, are introduced, optimized by means of FEA procedures and experimentally validated in detail, including the acoustic and PM performance. Further considerations are derived on the robustness of the solutions against the manufacturing imperfections. Comparing to the isotropic topologies, these innovative motor configurations show higher torque density, extended speed range, optimal torque quality and acoustic performance, ensuring lower active cost and structural simplicity. Therefore, they represent attractive candidates for high performance automotive applications.Negli ultimi anni l'interesse nel settore delle macchine sincrone a magneti permanenti ha riscontrato una notevole crescita. Questo e' stato determinato principalmente da importanti sviluppi nel campo della progettazione delle macchine elettriche, nei sistemi di controllo e nelle tecnologie dei magneti permanenti. Questi fattori hanno reso possibile la progettazione di macchine elettriche con elevata densita' di coppia, densita' di potenza, rendimento, basso costo unitamente ad ampi gradi di liberta' nella geometria e struttura della macchina. Tali requisiti sono fortemente ricercati nel campo automotive, soprattutto a seguito dell'introduzione di sempre piu' stringenti normative sull'efficienza energetica e sulle emissioni atmosferiche inquinanti. Questi aspetti hanno accelerato la transizione da sistemi di mobilita' tradizionali con motori a combustione interna a veicoli ibridi-elettrici e puramente elettrici, nella produzione industriale di massa. Inoltre, ulteriori requisiti, specialmente in macchine da trazione ed ausiliarie ad alte prestazioni, quali ad es. motori per servosterzo elettrico, stanno attualmente diventando sempre piu' importanti. Prestazioni in deflussaggio, qualita' della coppia (coppia di impuntamento ed oscillazione della coppia), smagnetizzazione, prestazioni acustiche e robustezza delle configurazioni devono essere tenute in conto, insieme a stringenti vincoli dimensionali, elettrici e termici tipici di azionamenti elettrici compatti ed integrati. A causa dell'incremento significativo ed instabilita' dei prezzi delle terre rare, della criticita' dei loro approvvigionamenti ed i relativi impatti ambientali, soluzioni prive di terre rare pesanti, senza terre rare od addirittura senza magneti permanenti, sono fortemente ricercate nel settore automotive. La principale tematica di ricerca di questo dottorato riguarda lo sviluppo di innovative procedure di analisi e sintesi di macchine sincrone a magneti permanenti per applicazioni automotive. Queste ultime spaziano da sistemi ausiliari a bassa coppia / bassa potenza, nella fattispecie motori per servosterzo elettrico, fino a applicazioni at alta coppia / alta potenza, quali ad es. motori da trazione. Questo lavoro fornisce una valutazione complessiva di differenti tipologie di macchine. Particolare attenzione e' dedicata allo studio di soluzioni con magneti permanenti privi di terre rare pesanti ed allo sviluppo di procedure di ottimizzazione ad elementi finiti ed analitiche della geometria del motore. Come menzionato precedentemente, tali metodologie tengono in considerazione numerosi vincoli elettromeccanici e differenti obiettivi. Per quanto riguarda le macchine da trazione, la ricerca si e' focalizzata sulla topologia di motori a riluttanza assistiti da magneti permanenti. L‘interesse attorno a tali macchine e' cresciuto negli ultimi anni soprattutto a seguito della crisi dei prezzi dei magneti permanenti a terre rare. Infatti, tali macchine rappresentano una soluzione alternativa a basso costo rispetto a motori a magneti permanenti tradizionali a causa di importanti vantaggi tecnici quali ad es. un ampio regime di velocita', competitivi valori di densita' di coppia ed efficienza, elevata capacita' di sovraccarico ed una robustezza della struttura. D'altra parte, uno dei principali svantaggi e' rappresentato dall'elevata oscillazione della coppia. Nel campo dei motori per servosterzo elettrico, differenti topologie, sia dotate di rotore isotropo che anisotropo ed equipaggiate con avvolgimenti concentrati, sono state valutate. Alcune nuove configurazioni, che sfruttano il principio della riluttanza e della concentrazione di flusso, sono introdotte, ottimizzate per mezzo di procedure ad elementi finiti ed infine validate per mezzo di misure sperimentali, includendo valutazioni delle prestazioni acustiche e quelle dei magneti permanenti. Ulteriori considerazioni sono tratte per quanto concerne la robustezza delle soluzioni nei confronti delle imperfezioni costruttive. Rispetto alle macchine isotrope, tali configurazioni sviluppano una densita' di coppia piu' alta, esibiscono un piu' ampio intervallo di velocita', maggiore rendimento raggiungendo un qualita' della coppia e prestazioni acustiche competitive ad un costo inferiore e con una buona semplicita' costruttiva. Esse si dimostrano, pertanto, dei candidati ottimali per applicazioni automotive ad alte prestazioni.
7
Nøland, Jonas Kristiansen. "A New Paradigm for Large Brushless Hydrogenerators : Advantages Beyond the Static System". Doctoral thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-317780.
Abstract (sommario):
The grid code, FIKS, from the Norwegian transmission system operator (TSO), Statnett, states that synchronous generators > 25MVA, must have a static excitation system. However, an improved brushless excitation system is in operation on some commercial power plants (36MVA, 93.75rpm & 52MVA, 166.67rpm) with grid-assisting performance beyond the conventional static system. The convenional diode bridge is replaced with a remote-controlled thyristor bridge on the shaft. If wireless communication is not allowed, a control signal through brushes should be employed instead. The thesis explores the expected new era for large brushless hydrogenerators. The proposed brushless system have benefits of reduced regular maintenance due to elimination of brushes and reduced unscheduled maintenance due to redundancy; causing a redused cost-of-energy. A six-phase exciter design with a hybrid-mode thyristor bridge interface leads to improved fault-tolerance, better controllability, minimized torque pulsations and reduced armature currents of the exciter. Excitation boosting (EB) capability is included in the brushless system without additional components or circuitry, contrary to the static excitation system. The brushless excitation system is made insensitive to voltage dips in the interconnected grid, causing improved fault ride-through (FRT) capability and power system stabilizer (PSS) actions.
8
Barsoum, Nader N. "Analysis and computation of instability mechanisms in rotating electrical machinery". Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328149.
9
Dupont, Préscillia. "Texturisation laser sélective des aciers électriques orientés et non orientés pour l'optimisation de leur perméabilité et des pertes dans les machines électriques tournantes". Electronic Thesis or Diss., Amiens, 2022. http://www.theses.fr/2022AMIE0065.
Abstract (sommario):
Les matériaux ferromagnétiques doux, souvent employés sous la forme de tôles laminées fines, sont utilisés dans les stators et rotors des machines électriques tournantes. Le rendement de ces machines est réduit par des pertes dites "pertes fer", dues aux mécanismes d'aimantation et aux courants induits. La nature du matériau reflétée par sa structure magnétique couplée à la géométrie, à l'anisotropie et à la texture de la surface sont autant de facteurs qui influent sur les performances électromagnétiques finales. Ces travaux de thèse ont donc pour objectif de proposer des matériaux magnétiques sur mesure par texturisation laser sélective de surface pour des dispositifs électromagnétiques tels que les machines électriques tournantes. L'applicabilité d'un tel procédé au niveau industriel pour des matériaux à grains orientés ou à grains non orientés dans les machines électriques nécessite de contrôler davantage la technologie et les spécifications du procédé dans le but d'optimiser les propriétés électromagnétiques. En effet, l'impact déterministe de cette technique sur la structure magnétique d'un matériau et ses performances observables (perméabilité magnétique et pertes fer) reste incomplètement appréhendé, modélisé et connu. Les conditions d'industrialisation doivent être analysée et optimisée vis-à-vis des contraintes techniques et économiques. On cherche donc ici à étudier l'impact d'une texturisation de surface par laser pulsé sur la structure magnétique en surface et en volume d'un matériau pour pouvoir les contrôler. L'adaptation des procédés laser avec augmentation de la vitesse de traitement est étudiée théoriquement, puis engagée et vérifiée expérimentalement pour correspondre aux ambitions d'industrialisation. Ainsi, ce travail effectué en très grande proximité avec le projet européen H2020 ESSIAL permettra de proposer différents traitements de surface adaptés aux machines tournantes pour ajuster certaines propriétés magnétiques, de façon théorique et expérimentaleSoft ferromagnetic materials, which are often used in the form of laminated sheets, compose rotating electrical machines' stators and rotors. The efficiency of those machines is reduced by losses called "iron losses", induced by magnetization mechanisms and eddy currents. Those magnetization reversal mechanisms can only be explained with the magnetic structure coupled to the material geometry, anisotropy and surface texture, which are also deterministic factors for the final electromagnetic performances. Then, present work aims at proposing tailor-made soft ferromagnetic materials by means of selective laser texturizing for electromagnetic devices such as rotating electrical machines. To apply such a process at an industrial level for grain-oriented and non-grain-oriented materials in electrical machines, it is necessary to better control the associated technology and specify the process in order to optimize electromagnetic properties. Indeed, the deterministic impact of this technic on a material's magnetic structure and its performances (magnetic permeability and iron losses) remains partially modelled and understood. The integration of such solution at the industrial scale must be analyzed and optimized regarding technical and economical constraints. In this work, the study of the impact of laser surface texturizing on magnetic structure (regarding surface and volume) of a material with the aim to control it is performed. Future industrialization requires to adapt the pulsed laser processes at a higher speed which has been theoretically studied, initiated and experimentally verified. To finish, present work performed in parallel with the H2020 European project ESSIAL will allow to propose different surface treatments adapted to rotating machines to adjust some quantifiable electromagnetic properties with the help of both experimental and theoretical tools
10
Chauvicourt, Fabien. "Vibro-acoustics of rotating electric machines: Prediction, Validation and Solution". Doctoral thesis, Universite Libre de Bruxelles, 2018. https://dipot.ulb.ac.be/dspace/bitstream/2013/271049/4/thesis.pdf.
Abstract (sommario):
The increase of greenhouse gas emission is commonly accepted to largely contribute to global warming, in part due to the massive use of non-renewable fossil energy sources. It is a reason why recently, beside other industrial sectors, electric mobility has been considered as the next generation for transportation systems. But the electrification of a vehicle introduces new challenges in its design since it involves different domains of expertise than the ones from Internal Combustion Engine (ICE) vehicles. In particular, Noise, Vibration and Harshness (NVH) comfort is significantly affected by powertrain changes, i.e. from ICE to electric machine. High and unpleasant acoustic noise from resonances may occur but can be addressed numerically to support decision making processes early enough in the design stages. The accurate prediction of its radiated acoustic noise then requires a thorough multi-physical understanding, from the system-level (electric machine) to the component-level (stator and rotor cores).First from a system-level point of view, two multi-physical modeling frameworks that use different model simplifications were implemented. By comparing simulated results to experimental measurements at each physical step of the modeling flow (electromagnetic, vibration, acoustic), it was shown that both models are accurate enough for pre-designing phases. It was also shown that considering only the stator core to contribute to the vibro-acoustic behavior of electric machines is a valid assumption.Second from a component-level point of view, the rotor and the stator core were investigated. The rotor influence on the complete machine structural dynamics was assessed. Beside the validated effects of different rotor topologies on the radiated noise, an analytical model was successfully developed to explain the occurrence of a particular vibration mode; whose explanation was still not offered in literature. In parallel, the stator core was studied, essentially because it is composed of hundreds of thin laminations stacked together which introduce difficulties in understanding its structural behavior. The effects of the laminations on the structural behavior of the stator core were studied numerically and experimentally as well. Two modeling guidelines were thus provided depending on the mode shape of interest and the computational resources available. The experimental studies comforted these two modeling approaches, and also permitted to highlight the importance of looking at the damping properties. Therefore it was shown that different lamination stacking techniques could affect significantly this damping.Finally the influence of the stacking technique (gluing, welding) on the structural behavior of the laminated compound motivated the implementation of an alternative solution to the mitigation of resonance phenomenon responsible for large acoustic noise. By using a skewed distribution of welding or glue lines, the technique aims at forcing laminations to vibrate with different phases which generates friction between them. The induced damping increases and then depends on the introduced asymmetry and on the mode shape considered. This innovative technique was validated experimentally and showed up to 7 times higher structural damping and 10 dB reduction in structural transfer function amplitudes.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
11
Drennan, Duncan Scott. "Design of a passive rotor transverse flux rotating machine". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50313.
Abstract (sommario):
Pages 6-12 missing.Thesis (MScEng)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: The transverse flux machine (TFM) offers the opportunity of high torque to volume ratios which makes it an excellent candidate for direct wheel drives and low speed generator applications. TFMs have a three dimensional flux path which eliminates iron laminates as a viable core material. Soft magnetic composites have been adopted in these machines due to their isotropic nature. There are three main variants of TFMs, namely, active rotor (with magnets on the rotor), passive rotor (with magnets on the stator), and reluctance (with no magnets). As a relatively recent development in electrical machines, the TFM still has many hurdles facing its adoption in industry. Some of these hurdles are high cogging torque, a difficult construction, and expensive materials. This thesis focuses on the design of a three phase 50 kW passive rotor machine. Finite element simulation is used to determine the optimal configuration, and the final machine is analysed in detail. The construction process and associated problems are also detailed. The completed machine did not perform to the desired specification, but much knowledge was gleaned about the TFM, the construction caveats, and future potential directions.
AFRIKAANSE OPSOMMING: Die transversale-vloed masjien (TFM) met sy hoe draaimoment tot volume verhouding, is 'n uitstekende kandidaat vir direkte wiel aandrywing en lae spoed generator toepassings. Die vioed pad van die masjiene is drie-dimensioneel, wat yster laminasies as kern materiaal elimineer. "Soft magnetic composites" kan gebruik word vir hierdie masjiene as gevolg van hulle isotropiese eienskappe. Daar bestaan drie hoof variante van die TFM, naamlik, die aktiewe rotor (met magnete op die rotor), passiewe rotor (met magnete op to stator), en reluktansie (sonder magnete). Die TFM is 'n redelike nuwe tipe masjien en daar is nog probleme wat opgelos moet word voordat die industrie sal begin om dit te gebruik. Van hierdie probleme is "cogging" draaimoment, 'n moeilike konstruksie en duur materiale. Die fokus van hierie tesis is op die ontwerp van 'n 50 kW drie-fase passiewe rotor masjien. Eindige element simulasie is gebruik om die optimale konfigurasie te kry, en 'n analise is gedoen op die finale masjien. Die konstruksie proses en die probleme wat daarmeer saam gaan is ook beskryf. Die prototipe masjien wat gebou is het nie aan sy oorspronklike spesifikasie voldoen nie, maar baie kennis is opgedoen oor die TFM, die konstruksie proses, en potensiele toekomende toepassings.
12
JUNIOR, HELIO DE PAIVA AMORIM. "A STUDY RELATED WITH THE ISOLATION CONDITION OF HIGH TENSION ROTATING ELECTRIAL MACHINES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1997. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7578@1.
Abstract (sommario):
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOO Monitoramento do Sistema de Isolamento em Máquinas Elétricas de Alta Tensão representa um avanço no que diz respeito ao planejamento operacional de uma indústria. Com posse de dados on-line referentes às condições apresentadas pelos isolamentos, as devidas precauções podem ser tomadas, evitando danos maiores. O trabalho apresentado tem como objetivo principal analisar um sistema de monitoramento desenvolvido pela CEA (Canadian Electrical Association), com suporte técnico da Ontario Hydro. O sistema chamado PDA (Partial Discharge Analyzer) mede, através de acopladores permanentes ou portáteis (capacitores), as Descargas Parciais nos enrolamentos estatóricos de grande máquinas de alta tensão. A quantificação exata das Descargas Parciais são indicadas das reais condições do isolamento. A análise do aparelho foi realizada em conjunção aos dados obtidos, tendo como referência a Companhia Siderúrgica Nacional (CSN). A partir de tais dados, é possível demostrar em que estágio atual de aproveitamento estamos em relação à utilização de tal aparelho e quais são os passos futuros para melhor compreensão das medidas.
The Monitoring of te Isolation System in High Tension Electrical Machines represents na advance in what concerns the operational planning of na industry. Knowing the on- line data referring to the conditions presented by the isolations, the necessary cautions can be taken, avoiding bigger damages. This work has as the main aim to analyze a monitoring system developed by the CEA (Canadian Electrical Association). The system is called PDA ( Partial Discharge Analyzer) and measures, through permanent or portable couplers (capacitors), the Partial Discharges is indicator of the isolation real conditions. The appliance analyses was made with the obtained data, having as reference the CSN. With this data, it is possible to show in what profiting stage of appliance and which are the future steps for a better comprehension of the measures.
13
Ipurale, Andrew. "Condition monitoring and fault detection of inverter-fed rotating machinery". Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25278.
Abstract (sommario):
Condition monitoring of rotating machinery is crucial in industry. It can prevent long term outages that can prove costly, prevent injury to machine operators, and lower product quality. Induction motors, often described as the workhorse of industry, are popular in industry because of their robustness, efficiency and the need for low maintenance. They are, however, prone to faults when used improperly or under strenuous conditions. Gearboxes are also an important component in industry, used to transmit motion and force by means of successively engaging teeth. They too are prone to damage and can disrupt industrial processes if failure is unplanned for. Reciprocating compressors are widely used in the petroleum and the petrochemical industry. Their complex structure, and operation under poor conditions makes them prone to faults, making condition monitoring necessary to prevent accidents, and for maintenance decision-making and cost minimization. Various techniques have been extensively investigated and found to be reliable tools for the identification of faults in these machines. This thesis, however, sets out to establish a single non-invasive tool that can be used to identify the faults on all these machines. Literature on condition monitoring of induction motors, gearboxes, and reciprocating compressors is extensively reviewed. The time, frequency, and time-frequency domain techniques that are used in this thesis are also discussed. Statistical indicators were used in the time domain, the Fourier Transform in the frequency domain, and Wavelet Transforms in the time-frequency domain. Vibration and current, which are two of the most popular parameters for fault detection, were considered. The test rig equipment that is used to carry to the experiments, which comprised a modified Machine Fault Simulator -Magnum (MFS-MG), is presented and discussed. The fault detection strategies rely on the presence of a fault signature. The test rig that was used allows for the simulation of individual or multiple concurrent faults to the test machinery. The experiments were carried out under steady-state and transient conditions with the faults in the machines isolated, and then with multiple faults implemented concurrently. The results of the fault detection strategies are analysed, and conclusions are drawn based on the performances of these tools in the detection of the faults in the machinery.
14
Obaid, Ramzy R. "Detection of rotating mechanical asymmetries in small induction machines". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/13527.
15
Lawler, Clinton T. (Clinton Thomas). "A two-phase spherical electric machine for generating rotating uniform magnetic fields". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39839.
Abstract (sommario):
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 133-138).
This thesis describes the design and construction of a novel two-phase spherical electric machine that generates rotating uniform magnetic fields, known as a fluxball machine. Alternative methods for producing uniform magnetic fields with air-cored solenoidal magnets are discussed and evaluated. Analytical and numerical models of these alternatives are described and compared. The design details of material selection, slot geometry, and mechanical connections are described for the fluxball machine. The electrical properties of the machine are predicted and measured. Based on these properties, two modes of operation for the fluxball machine, normal and resonant, are described, and reference tables of important operating parameters are given. The drive and measurement circuitry for the fluxball machine are described. The magnetic properties of the fluxball machine are measured using Hall effect sensors. The calibration of two different Hall effect sensors is performed, providing the ability to measure the magnetic fields accurately to ±1%. Measurements of the magnetic field in the uniform field region are taken and compared with predicted values. The attenuation and distortion of the magnetic fields due to diffusion through the inner fluxball winding is measured as a function of operating frequency.
(cont.) Finally, future uses of this machine for various applications are discussed. The fluxball machine provides uniform fields in the inner volume and point magnetic dipole fields in the exterior volume. Both regions are extremely useful for conducting controlled magnetic fields experiments. The fact that the machine can produce rotating fields of these types makes it particularly useful for applications in ferrofluid research and in experimental research related to large rotating machinery.
by Clinton T. Lawler.
S.M.
Nav.E.
16
Lawler, Clinton T. "A two-phase spherical electric machine for generating rotating uniform magnetic fields". Thesis, Monterey, California. Naval Postgraduate School, 2007. http://hdl.handle.net/10945/2995.
Abstract (sommario):
This thesis describes the design and construction of a novel two-phase spherical electric machine that generates rotating uniform magnetic fields, known as a fluxball machine. Alternative methods for producing uniform magnetic fields with air-cored solenoidal magnets are discussed and evaluated. Analytical and numerical models of these alternatives are described and compared. The design details of material selection, slot geometry, and mechanical connections are described for the fluxball machine. The electrical properties of the machine are predicted and measured. Based on these properties, two modes of operation for the fluxball machine, normal and resonant, are described, and reference tables of important operating parameters are given. The drive and measurement circuitry for the fluxball machine are described. The magnetic properties of the fluxball machine are measured using Hall effect sensors. The calibration of two different Hall effect sensors is performed, providing the ability to measure the magnetic fields accurately to +or- 1%. Measurements of the magnetic field in the uniform field region are taken and compared with predicted values. The attenuation and distortion of the magnetic fields due to diffusion through the inner fluxball winding is measured as a function of operating frequency. Finally, future uses of this machine for various applications are discussed.Contract number: N62271-97-G-0026
US Navy (USN) author.
17
Garibaldi, Michele. "Laser additive manufacturing of soft magnetic cores for rotating electrical machinery : materials development and part design". Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52326/.
Abstract (sommario):
This research work addresses the application of Additive Manufacturing (AM) technologies in novel electrical machinery. The unrivalled design freedom offered by AM has the potential to revolutionise the way rotating electrical motors are designed and manufactured. The thesis investigates the possibility offered by AM to advance the design of electrical machines for lightweight and high performance, with potential in several industrial sectors, including automotive and aerospace. In particular, we investigate how the performance of electrical motors can be improved by manufacturing the soft magnetic rotor core using Selective Laser Melting (SLM) and how the consequent design choices affect the component's performance from a torque-to-weight perspective. First, the metallurgical and soft magnetic properties of high-silicon steel (Fe-6.7%wt.Si) parts produced by Selective Laser Melting (SLM) will be characterised and discussed as function of the processing parameters and post-processing heat-treatments. The results of this research show that, by means of SLM, high-silicon steel parts with permeability (above 24000) and hysteresis loss (coercivity below 20 A/m) comparable to the ones of laminated high-silicon iron can be produced. Then, FEM-based modelling and Topology Optimisation (TO) will be employed to design the rotor core of a surface-mount Permanent Magnet (PM) machine in order to achieve maximum torque-to-weight ratio while maintaining structural integrity. Importantly, three-dimensional FEA results show that the weight of an existing PM rotor core can be slashed by 50% without affecting its torque performance when the proposed TO scheme is employed and the actual mechanical and magnetic properties of the SLM material are considered. Finally, we suggest that further research should be aimed at extending the range of applicability of the proposed TO scheme to other machine topologies (i.e., Synchronous Reluctance), as well as at the adjustment of the alloy's chemistry for improved ductility to avoid the risk of in-process cracking.
18
Halligan, Gary. "Fault detection and prediction with application to rotating machinery". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Halligan_09007dcc80708356.pdf.
Abstract (sommario):
Thesis (M.S.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 25, 2009) Includes bibliographical references.
19
O'Leary, Beth Andrews. "Analysis of high-speed rotating systems using Timoshenko beam theory in conjunction with the transfer matrix method /". Online version of thesis, 1989. http://hdl.handle.net/1850/10608.
20
Kohutek, Tomáš. "Diagnostika vibrací strojů při kusových zkouškách". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318531.
Abstract (sommario):
This master thesis deals with the vibration diagnostics of machine vibrations during unit tests in industrial company Siemens Electric Machines s.r.o Drásov. In the master thesis is elaborated a design of the diagnostic system which contains selected methods of vibration diagnostics, methology, procedure of measurement and evaluation of measured values. The part of master thesis is also a practical example of measurement on which the mentioned system is tested.
21
Farah, Philippe-Siad. "Étude de la réduction des vibrations des machines synchrones". Grenoble INPG, 1995. http://www.theses.fr/1995INPG0087.
Abstract (sommario):
Ce mémoire concerne l'étude de la réduction des vibrations des machines synchrones. L'objectif est de proposer une structure optimisée au plan vibratoire, et de mettre au point un dispositif de contrôle actif des vibrations. L'essentiel des informations utiles à la compréhension des mécanismes sources de vibrations est exposé au premier chapitre. Il est montré que le caractère non sinusoïdal de l'induction dans l'entrefer est source de vibrations (électromagnétiques. L'étude expérimentale, sujet du deuxième chapitre sert à définir les éléments de conception d'une machine optimisée au plan vibratoire. Un stator à encoches inclinées et un rotor à aimantations à saturation optimisées ont été retenues. Le troisième chapitre comprend la définition précise d'une maquette optimisée ainsi qu'une étape de validation expérimentale. Il est ici montré que l'usage d'aimants tuile au rotor et le recours à des techniques d'optimisation de structure constituent des outils efficaces pour la réduction des vibrations des machines synchrones. Le dernier chapitre est consacré à la mise en place d'un dispositif de compensation active des vibrations. Cette méthode, fiable et efficace a permis d'obtenir une réduction notable des vibrations, et ce avec des moyens simples et peu coûteux en énergie
22
Bruguier, Cyrille. "Commande d'une machine synchrone à aimants sans capteur mécanique". Grenoble INPG, 1996. http://www.theses.fr/1996INPG0133.
Abstract (sommario):
Les machines synchrones à aimants permanents sont de plus en plus utilisées dans les applications de petites et moyennes puissances. Dans les techniques de commande les plus répandues de ces machines, la position rotorique doit être connue. Les capteurs utilisés sont coûteux et posent des problèmes de fiabilité, de maintenance ou d'encombrement. Notre travail a porté sur la définition, l'étude (analytique et en simulation) et la mise en oeuvre expérimentale d'estimatives numériques de vitesse et position. Ces estimations sont basés sur les mesures de courants de phase et des grandeurs de commandes projetées dans un repère tournant estimé. Les composantes du vecteur courant sont reconstituées à partir des équations électriques de la machine et comparées aux courants mesurés. Les erreurs obtenues sont fonction de l'erreur de position et de vitesse entre le repère estimé et le repère tournant lié au rotor. Ces erreurs sont asservies à zéro grâce à des correcteurs dont les sorties sont la vitesse et la position estimée. Sauf à très basse vitesse, les résultats obtenus sont très satisfaisants et comparables à ceux obtenus avec un capteur mécanique. Une première structure spécifique aux basses vitesses est proposée ainsi qu'une méthode permettant de connaître la position à l'arrêt
23
McKinnon, Douglas John Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Novel efficiency evaluation methods and analysis for three-phase induction machines". Awarded by:University of New South Wales. Electrical Engineering and Telecommunications, 2005. http://handle.unsw.edu.au/1959.4/21869.
Abstract (sommario):
This thesis describes new methods of evaluating the efficiency of three-phase induction machines using synthetic loading. Synthetic loading causes the induction machine to draw full-load current without the need to connect a mechanical load to the machine's drive shaft. The synthetic loading methods cause the machine to periodically accelerate and decelerate, producing an alternating motor-generator action. This action causes the machine, on average over each synthetic loading cycle, to operate at rated rms current, rated rms voltage and full-load speed, thereby producing rated copper losses, iron loss and friction and windage loss. The excitation voltages are supplied from a PWM inverter with a large capacity DC bus capable of supplying rated rms voltage. The synthetic loading methods of efficiency evaluation are verified in terms of the individual losses in the machine by using a new dynamic model that accounts for iron loss and all parameter variations. The losses are compared with the steady-state loss distribution determined using very accurate induction machine parameters. The parameters were identified using a run-up-to-speed test at rated voltage and the locked rotor and synchronous speed tests conducted with a variable voltage supply. The latter tests were used to synthesise the variations in stator leakage reactance, magnetising reactance and the equivalent iron loss resistance over the induction machine's speed range. The run-up-to-speed test was used to determine the rotor resistance and leakage reactance variations over the same speed range. The test method results showed for the first time that the rotor leakage reactance varied in the same manner as the stator leakage and magnetising reactances with respect to current. When all parameter variations are taken into account there is good agreement between theoretical and measured results for the synthetic loading methods. The synthetic loading methods are applied to three-phase induction machines with both single- and double-cage rotors to assess the effect of rotor parameter variations in the method. Various excitation waveforms for each method were used and the measured and modelled efficiencies compared to conventional efficiency test results. The results verify that it is possible to accurately evaluate the efficiency of three-phase induction machines using synthetic loading.
24
Le, Coat Gwenaëlle. "Discrétion électromagnétique des machines électriques tournantes". Grenoble INPG, 1997. http://www.theses.fr/1997INPG0108.
Abstract (sommario):
Toute machine électrique est source de fuites électromagnétiques externes. Ces champs, de valeurs faibles d'un point de vue électrotechnique classique, peuvent se révéler néfastes pour certaines applications, notamment dans le domaine de la détection. L'objectif de cette thèse est donc la discrétion électromagnétique des machines électriques tournantes. Un banc d'essais et un protocole de mesures ont été mis en place. Ils permettent d'étudier avec précision la signature électromagnétique des machines à différentes distances, ainsi que l'influence de certains paramètres comme la nature des flasques ou la présence du rotor. Les effets d'une excentricité sur le rayonnement ont également été évalués dans une optique de prévention et de maintenance des machines électriques. Des modèles numériques, utilisant les éléments finis, ont ensuite été développés. Le modèle 2D ne convient que pour des études qualitatives, ses hypothèses ne rendant pas suffisamment compte de la réalité. L'intérêt du modèle 3D réside dans sa capacité à représenter correctement les phénomènes physiques à l'extérieur de la machine. Un modèle analytique est également proposé dans ce mémoire. De conception simple, basée sur la représentation par moments dipolaires équivalents, il aide à la compréhension de la signature électromagnétique. Enfin, grâce à ces modèles, des solutions de compensations optimales des fuites par un blindage actif, sont envisagées après une présentation de l'état de l'art des solutions utilisées actuellementEvery electrical machine produces electromagnetic stray fields. Those fields have low values in term of classical electrotechnics, but in other applications they seem high, like for example in magnetic detection. In this way the aim of this thesis is the reduction of electromagnetic stray fields of electrical machines. An experimental set has been installed. It allows to study, with a great accuracy, the electromagnetic signature of machines and tbe influence of sorne elements as the presence of end shields, and the rotor. The effect of eccentricity has been shown in a purpose of machine safety and maintenance. Numerical models have been developed. The 2D model gives only qualitative results because of its hypothesis : end windings not taken Înto account and infinite length of the machine. The 3D model is able to represent physical phenomena outside the machine. A simple analytical model is also described in this thesis. It is based on the representation by equivalent magnetic dipoles. It helps to understand the signature of the machines. Finally, thanks to those models, solutions for stray fields reduction, as an active shielding, have been considered, after a review of the present usual solutions
25
Holmberg, Pär. "Modelling the transient response of windings, laminated steel coresand electromagnetic power devices by means of lumped circuits : With special reference to windings with a coaxial insulation system". Doctoral thesis, Uppsala University, Department of High Voltage Research, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-548.
Abstract (sommario):
Electromagnetic transients impinging on electromagnetic power devices - such as electric machines, transformers and reactors - can stress the design severely. Thus the magnitudes of the transients are often decisive for the design of the devices. Further, the operation of a device can be transient in itself. This is the case for the explosive magnetic flux compression generator (EMG) and a ferromagnetic actuator.
Models are presented that are mainly intended for transients in the millisecond range and faster. Hence, eddy currents and the related skin and proximity effect become significant in windings, magnetic cores and in the armatures of the devices. These effects are important for, e.g., the damping of the transients. Further, the displacement current in the insulation of the winding is significant. It changes the response of the windings dramatically, as it manifests the finite velocity of propagation of the electromagnetic fields. Under such circumstances, reflections and excited resonances can make the transient voltage and current distribution highly irregular.
Induced voltages are modelled with self and mutual inductances or reluctances combined with winding templates. The displacement currents are modelled with capacitances or coefficients of potential. Cauer circuits and their dual form are used to model eddy currents in laminated cores and in conductors. The Cauer circuit enables one to consider hysteresis and the non-linear response of a magnetic core. It is also used to model the eddy currents in the moving armature of an EMG.
A set-up is presented that can be used to study the transient voltage and the current distribution along a coil.
The transient response of coaxially insulated windings is analysed and modelled in detail. A lumped circuit model is developed for a coil, DryformerTM - the new high-voltage transformer - and PowerformerTM, the new high-voltage generator. An alternative model, a combined lumped circuit and FEM model, is presented for a coaxially insulated winding in two slot cores.
26
Jandaud, Pierre-Olivier. "Étude et optimisation aérothermique d'un alterno-démarreur". Thesis, Valenciennes, 2013. http://www.theses.fr/2013VALE0018/document.
Abstract (sommario):
Cette thèse porte sur l’étude et l’optimisation aérothermique d’un alterno-démarreur utilisé dans les véhicules hybrides. Ces machines produisant beaucoup plus de puissance qu’un alternateur classique, leur refroidissement est donc critique. La machine est modélisée en utilisant la méthode nodale en régime permanent qui utilise des réseaux de conductances thermiques. Pour alimenter le modèle, on utilise des corrélations issues de la littérature pour modéliser les transferts convectifs et on effectue des calculs CFD de la machine complète pour obtenir la répartition des débits. Les résultats obtenus numériquement sont ensuite validés expérimentalement à l’aide d’essais par Vélocimétrie par Images de Particules et d’essais thermiques par mesure thermocouples. Dans un deuxième temps, on couple un algorithme d’optimisation au code pour obtenir une géométrie de la machine optimale d’un point de vue thermique. La méthode retenue est l’Optimisation par Essaim Particulaire (PSO). L’optimisation se fait sur la taille des têtes de bobines, la position des ventilateurs et la section des canaux rotoriques. On obtient des géométries différentes selon les objectifs que l’on cherche à atteindre. La dernière partie de la thèse porte sur l’optimisation multi-objectifs d’un dissipateur située sur la partie électronique à l’arrière de l’alternateur : le dissipateur doit refroidir le plus possible l’électronique sans pour autant perturber l’écoulement. On étudie aussi plusieurs formes d’ailettes pour atteindre ces objectifsThe goal of this thesis is the aero-thermal study and optimization of a starter-alternator used in hybrid cars. This kind of machines being more powerful than a regular alternator, their cooling is critical. The machine is modeled using lumped method in steady state which uses networks of thermal conductances. The inputs for the model are obtained using correlations from bibliography for the convective heat transfers and three dimensional CFD for the flow rates inside the machine. The numerical results are validated by experimental results with PIV for the fluid results and a machine fitted with thermocouples for the thermal part. In the second part, the thermal code is coupled with an optimization algorithm to obtain an optimal geometry of the machine from a thermal point of view. The method chosen is Particle Swarm Optimization (PSO). The parameters are the sizes of the end-windings, the positions of the fans and the cross section of the rotor channels. For different objectives, different optimal geometries are obtained. The last part of this work aims at the multi-objectives optimization of a heat sink located at the back of the machine. The heat sink has to be thermally efficient but should not affect the flow. Different shapes of fins are also studied
27
Pavlík, Josef. "Vybrané problémy s diagnostiky izolačních systémů točivých elektrických strojů". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233987.
Abstract (sommario):
This dissertation thesis deals with the measurement of insulation resistance for rotating electrical machines and polarization indices calculated from them. The first part contains a short theoretical introduction, methods of measurement and basic formulas for calculations. The second part discusses the results obtained in laboratory measurements in both the model and the real coil of high voltage machine. There are also elucidated some of the principles and causes of some phenomena with which the measurement of insulation resistance is encountered. The third part deals with the results of measurements on real machines. There are mainly discussed the dependences of insulation resistance and polarization index on the influences that occur in measurements such as temperature measured insulation, moisture in the insulation, but also the influence of measuring instruments on the measured values. It is also expressed how much these factors affect the measurement results. In addition, this part deals with some other influences that have a negative affect on the measurement of insulation resistance. There is processed a new methodology for measuring insulation resistence in the fourth part of this thesis. The need to develop a metodology of measuring is based on the needs of engineering practice, where is considerable inconsistency of measurement in the present time. Measurement, and often performed on the same machine, are not nowadays often comparable, because measurements are not met even the basic rules resulting from the findings of research and development, which were discovered in the last few decades. Measurement of insulation resistance in our nowdays methodology stagnated on the level of the seventies of 20th century. For this reason, we have developed a new methodology of measurement that takes into account all significant influences affecting the measurement. The purpose of the methodology is to ensure full repeatability and comparability of measurements not only on the same machine but on machines of the same type, in optimal cases, the machines of different types. There are the chapters "The objectives of the work" and "Conclusion" the part of the work. A very important chapter is "The contribution of thesis", which summarizes the original results of this work and results, the use of which is expected in engineering practice.
28
Donát, Martin. "Komplexní analýza modálních vlastností elektrických strojů točivých". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234347.
Abstract (sommario):
This dissertation thesis deals with the computational modelling of the dynamic response of the rotating electrical machine structure on the application of the magnetic forces. Apart from the dynamic response of the ideal symmetrical machine, the influence of the air gap eccentricity on the dynamics response is studied in this work. A basic type of the air gap eccentricity, which is caused by eccentric mounting of the rotor pack on the shaft of the rotor, is considered. The calculations the dependence of the magnetic forces on the time and a misalignment of the rotor pack are performed as first. The computational model of the magnetic field of the rotating electrical machine, which is based on solution of the electromagnetic coupled field analysis by finite element method, is used for this purpose. An analysis of the influence of the unbalanced magnetic pull and the stiffness of some parts of the machine on the modal properties of the machine is performed in the second part of this thesis. A third part of this thesis is focused on the calculation of the dynamic response of the machine during the steady state operation of the machine and the influence of the rotor pack misalignment on the dynamic response is studied. The obtained results showed that the tangential components of the magnetic forces, which act on the stator pack, excite significant torsional vibration of the stator. Besides the vibration of the stator of the machine, the influence of the rotor pack misalignment on the sound power of the machine, vibration of the rotor, loads of rotor bearings and air gap eccentricity is studied in this thesis.
29
Montasser, Yuseph. "Design and Development of a Power Modulator for Insulation Testing". Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2895.
Abstract (sommario):
Variable speed drives allow for more precise speed control of induction motors, are of high power factor, and offer fast response characteristics, compared to older technologies, such as motor-generator sets and eddy current clutches. However, due to the high switching frequencies as well as the high dV/dt in the output increased dielectric stresses are produced in the insulation system of the motor they supply. Due to the use of these solid state drives there have been concerns of premature failure in large, medium and high voltage, motors. To fully understand and deal with these concerns requires studying the degradation mechanisms, in the insulation system, caused by these drives; which, on an actual motor is both extremely costly as well as impractical. Therefore, coil samples which accurately represent the construction of the actual insulation system, must be aged and studied instead. In addition, to ideally replicate the aging process, the same waveform that the motor is subjected to must be applied to these samples. As a result of this requirement, a low power, two-level, high voltage PWM inverter has been built to replicate the most important characteristics of the output waveform of a variable speed drive. This power modulator allows for testing the insulation systems considering a real PWM waveform in which both the fast pulses and the fundamental low frequency are included. The results of these tests show that the effects of PWM waveforms cannot be entirely replicated by a unipolar pulse generator.
30
Abboud, Rita. "Méthode de mesure sans contact de la température intégrée au rotor d’une machine électrique tournante au moyen d’une fibre optique à réseaux de Bragg". Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2645.
Abstract (sommario):
Dans le domaine des systèmes de transport, des problèmes de chauffage apparaissent avec l'augmentation de la température dans différents types de machines électriques. Dans la conception classique des machines électriques, l'analyse thermique doit être prise en compte dans la conception initiale, le contrôle et la surveillance des machines électriques. La mesure de la température locale, en particulier dans le rotor, est importante pour plusieurs raisons telles que l'extension de la durée de vie des composants de la machine électrique et la localisation des points chauds à l'intérieur de la machine, ce qui permet de développer des systèmes de refroidissement appropriés et de protéger la machine. De nombreuses approches pour la mesure de la température peuvent être utilisées telles que les thermocouples, les thermistances, les capteurs infrarouges ou les caméras infrarouges. Cette thèse présente une technique sans contact qui mesure la température du rotor d'une machine tournante en utilisant un capteur à réseaux de Bragg (FBGs). La surveillance de la température locale, en particulier à l'intérieur du rotor, est importante afin de détecter le vieillissement thermique précoce de la machine. Les points chauds dans les parties rotatives peuvent être localisés en utilisant cette technique. L'originalité principale du travail proposé est de mesurer des températures élevées (70°C) avec une vitesse de rotation élevée (860 RPM) des machines tournantes et surtout d'intégrer le capteur FBG dans un rotor électrique de véhicules à petite échelle géométrique. La réponse du capteur FBG a été simulée en utilisant la méthode de la matrice de transfert (TMM). Ensuite, le FBG a été calibré en utilisant un four de chauffage fabriqué dans notre laboratoire et la température a été modifiée de 20 °C à 70 °C. Une machine rotative avec un FBG intégré a ensuite été conçue et fabriquée. La température du rotor a été modifiée pendant la rotation de la machine. Les décalages de longueur d'onde dus aux variations de température ont été mesurés expérimentalement jusqu'à 860 RPM. Une sensibilité à la température de 4.7 pm/°C a été atteinte expérimentalement. La capacité de ce capteur à surveiller les variations de température du rotor en temps réel a été validée expérimentalementIn the transportation system domain, heating problems appear with the temperature increase in different types of electrical machines. In the classical design of electrical machines, thermal analysis should be considered in the initial design, control and monitoring of electrical machines. The measurement of local temperature especially in the rotor is important for several reasons such as extending the lifetime of the electrical machine components, and localizing the hot spots inside the machine which allows the development of appropriate cooling systems and protects the machine. Numerous approaches for temperature measurement can be used such as thermocouples, thermistors, infrared sensors or infra-red cameras. This thesis presents a non-contact technique that measures the temperature of the rotor of a small machine using Fiber Bragg Gratings (FBGs) sensor. Monitoring local temperature especially inside the rotor is important in order to detect early thermal aging of the machine. Hot spot in the rotating parts can be localized by using this technique. The main originality of the proposed work is measuring high temperatures (70°C) with high speed of rotation (860 RPM) of rotating machines and most importantly integrating the FBG sensor into a geometrically small scale electrical rotor of vehicles. The FBG sensor response has been simulated using Transfer matrix method (TMM). After that, the FBG has been calibrated from 20 °C to 70 °C using a heating furnace fabricated at our laboratory. A small rotating machine with embedded FBG has then been designed and fabricated. The temperature of the rotor has been changed while rotating the machine and wavelength shifts due to temperature variations have been experimentally measured up to 860 RPM. A temperature sensitivity of 4.7 pm/°C have been experimentally reached. The ability of this sensor to monitor real time temperature variations of the rotor has been experimentally validated
31
Spornic, Sorin Aurel. "Automatisation de bancs de caractérisation 2D des tôles magnétiques : influence des formes d'onde sur les mécanismes d'aimantation". Phd thesis, Grenoble INPG, 1998. http://www.theses.fr/1998INPG0154.
Abstract (sommario):
Le travail de notre thèse porte sur le comportement des matériaux magnétiques doux soumis à des variations 2D quelconques du vecteur induction magnétique dans le plan de la tôle. De telles conditions apparaissent par exemple dans les machines électriques tournantes ou les transformateurs triphasés. Les travaux précédents ont été limités à des inductions de formes simples (cercles ou ellipses parcourues à vitesse angulaire constante), qui ne permettent pas de décrire de manière complète le comportement des matériaux. Dans un premier temps nous avons dû élaborer un outil de caractérisation magnétique complète en 2D. Nous avons équipé les deux RSST du LEG d'un système de pilotage informatisé. La précision et la stabilité des mesures ont été nettement améliorées, tout en élargissant l'intervalle des fréquences. Son asservissement numérique a permis l'obtention pour la première fois de formes d'onde 2D complexes de l'induction. Finalement le banc de mesures a été entièrement automatisé. Par la suite cet outil nous a permis l'étude de plusieurs matériaux magnétiques doux, tels que le FeNi, le FeCo et le FeSi NO. - D'abord ces trois matériaux ont été soumis à des inductions circulaires. Nous avons étudié le comportement en fonction du niveau de l'induction et de la fréquence et le comportement réversible, qui permet la mise en évidence de Panisotropie. Le FeNi a permis d'obtenir la courbe complète et atypique des pertes en fonction du niveau d'induction en champ tournant et de valider un modèle de prédiction de celles-ci. Le comportement vectoriel de la loi B(H) dans ce matériau a été également analysé et une tentative de modélisation de l'évolution du champ magnétique a été proposée. - Ensuite nous avons étendu notre étude aux formes d'onde observées dans un moteur asynchrone triphasé. Nous avons testé une méthode de calcul approchée pour les pertes 2D. Finalement, nous avons mis en évidence l'importance de la dérivé temporelle du vecteur induction sur le comportement magnétique et les pertesThe aim of this dissertation is the study of soft magnetic materials under arbitrary vector 2D excitation, turning into the sheet plane. Such conditions appear, for example, inside rotating electric machines or inside three-phase transformers. Previous work has used simplified flux density paths, such as circles or ellipsis covered at constant angular speed, that cannot completely describe the materials'behaviour. The first part of this work was accomplished by the élaboration of a complète 2D magnetic characterisation device. The two RSST of LEG received a computerised driving System (CDS), which clearly improved the measurements accuracy and stability and enlarged the frequency domain. The CDS digital waveform control part allowed for the first time the obtention of complex flux density paths. Finally, the measurement System was completely automated. Thanks to the CDS, the investigation of some soft magnetic materials, such as NiFe, CoFe and NO SiFe, was realised. - First, thèse three materials were characterised under circular flux. The magnetic behaviour was studied with respect to flux and frequency level and also the réversible behaviour, in order to get an anisotropy image. The complète atypical losses évolution could be seen in this manner in the case of NiFe, and a prédiction model was validated. The vector law B(H) was also analysed and a model for the field strength évolution was attempted. - Then this study was enlarged to waveforms observed inside a three-phase induction motor. A2D losses estimation was tested. Finally, the importance of the derivative of the flux density vector with respect to time was highlighted on the magnetic behaviour and the magnetic losses development
32
Rybnikář, Petr. "Matematický model zátěžového pracoviště točivých elektrických strojů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-449715.
Abstract (sommario):
This work deals with the creation of a mathematical model of load workplace for rotating electrical machines. The first part provides a general description of servomotors and their mathematical equations. The second part describes the commissioning and connection of the PLC to the inverter and the subsequent creation of PLC programs. The last part describes the creation of the PMSM model with its control and then verified the validity of the model and the real machine.
33
Perrin-Bit, Rémy. "Modélisation des machines électriques tournantes par la méthode des éléments finis tridimensionnels : calcul des grandeurs magnétiques avec prise en compte du mouvement". Grenoble INPG, 1994. http://www.theses.fr/1994INPG0091.
Abstract (sommario):
Un code de calcul utilisant la méthode des éléments finis nodaux a été développé. Ce logiciel permet de simuler, en trois dimensions, les machines électriques tournantes. Les phénomènes magnétiques sont calculés par une formulation en potentiel vecteur magnétique A. Pour modéliser les moteurs électriques quel que soit leur fonctionnement, nous utilisons une résolution en régime transitoire avec couplage de l'équation générale de la mécanique. Une méthode de prise en compte du mouvement et plus généralement des limites a été étudiée et utilisée dans le logiciel. Des conditions aux limites de type champ tangentiel, champ normal, symétrie et périodicité (cyclique, anti-cyclique) ont été implémentées. Des maillages tridimensionnels spécifiques aux machines tournantes ont été construits afin de remédier au manque de puissance des systèmes informatiques actuels (1994). Afin de réduire les temps de résolution, inhérents à la méthode de résolution en pas à pas dans le temps tridimensionnel, nous avons pris soin d'optimiser le logiciel dans sa structure général et dans chacune de ses routines de calcul. Le logiciel a été validé sur l'étude d'un moteur à courant continu ainsi que sur un moteur à réluctance variable
34
Sikora, Michal. "Inovace systému chlazení točivých elektrických strojů s využitím CFD metod". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233962.
Abstract (sommario):
This thesis deal with design and implementation of innovative cooling method, intended primarily for medium-power synchronous generators. The main objective of this proposal is to remove the large heat exchanger connected to generator. This heat exchanger unduly increases the space requirements for the machine location. The proposed solution is to use a direct water-cooled stator. It is assumed that the rotor winding will be still cooled by air. Unlike current cooling system, the hot air from the rotor can be cooled in smaller cooler inside the generator. In this work are described methods which can be used for design of water cooling basic parameters, taking required temperatures into account. A small induction motor was selected for practical verification of the proposed cooling concept. This motor was modified into two variants - related to the old cooling of synchronous generators and related to the proposed solution. Both of these variants were measured and compared with each other. Subsequently, CFD models of these two variants were set up. Measured temperatures were used for debugging of models and identification of material properties of components of these machines. The final model of water-cooled variant also makes it possible to simulate the work of motor for higher performance and to determine the overload compared with the old cooling variant. Some knowledge and experience obtained from the small water-cooled induction machine were used in the design of water-cooling for large synchronous generator. In a similar way, CFD models of the old variant of cooling and proposed variant of water- cooling were created. Although these models were not verified by actual measurements on the generators, the results indicated that the application of water-cooling in this type of machine is appropriate and provides many benefits.
35
DERISZADEH, ADEL. "Analysis, modeling and excitation control of three-stage brushless starter-generators for aircraft applications". Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2712202.
Abstract (sommario):
In the aircraft application, due to space constraints, employing integrated starter-generator is an efficacious solution. Among various electric machines, wound-rotor synchronous machine (WRSM) offers advantages of high reliability, sufficient controllability, the high power factor in a wide range of torque-speed plan, etc. The requirement of supplying rotor of WRSM is its main drawback. Since in aircraft
application, safety is a critical demand, brushless type of WRSM is a practical solution. A conventional structure of brushless WRSM consists three electrical machines which are mounted on the same shaft. Therefore, this kind of WRSM is called three-stage brushless synchronous machine. The first stage of the machine is Pre-exciter which is usually a small PMG. The second stage in an inverse synchronous machine with stationary single-phase field and rotating armature which is called Main Exciter (ME). The third stage is the Main Generator (MG). Electrically, ME is connected to the MG by means of a rotating rectifier. The existence of the rotating rectifier connected between the armature windings of ME and field winding of MG significantly increases the nonlinearity of the system. In consequence, investigating the nonlinear behavior of the rotating rectifier plays a key role in studying of the brushless synchronous starter-generator.
In this thesis, using analytical, numerical and experimental analysis, different operation modes of the three-stage brushless synchronous machine are investigated. Using revolving field theory, analytical description of the relationship between the stationary pulsating field flux of ME and its armature voltages is presented. Because of single-phase field winding of ME, at standstill and low-speed operations, for exciting field winding of ME, AC excitation is required. Then, by speed increasing, AC excitation must be switched to DC. Since field excitation of ME is variable, induced armature voltages of ME are different in various operating points. In this thesis, it is explained that during the starting process of the starter-generator, armature voltages of ME are severely unbalanced. Therefore, for the sake of modeling and studying, a model of rotating rectifier with an ability to deal with a wide range of unbalanced conditions is required. As the first step, in this thesis, a novel model of the uncontrolled rectifier with a capability of considering unbalanced input voltages and harmonics in AC-side is proposed.
36
Pařízek, Daniel. "Návrh algoritmu výpočtu rotoru elektrického stroje s ohledem na napěťově deformační poměry a kritické otáčky". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401514.
Abstract (sommario):
The Master's thesis deals with the mechanical design of electric machine rotor. Within the first two chapters of the practical part of the thesis two simplified computational models of the rotor (level 1 models) are compiled. Specifically, the model of flexible rotor mounted on rigid supports and model of rigid rotor mounted on flexible supports. The essence of these computational models lies in solvability using simple equations. Using these models can save time when constructing a pre-design of the rotor geometry. The following chapter is devoted to comparing different approaches to computational modeling of rotor using FEM. A predetermined preliminary design of a high-speed massive rotor is investigated. Computational models of different levels at stress-strain analysis and modal analysis are presented. It also includes a suggestion on how to proceed effectively in a given analysis.
37
Maalouf, Haddad Amira. "Sensorless control of brushless synchronous starter generator including sandstill and low speed region for aircraft application". Thesis, Cachan, Ecole normale supérieure, 2011. http://www.theses.fr/2011DENS0008.
Abstract (sommario):
In More Electric Aircraft, different power system activities are attributed to electrical means such as the start-up of the main engine. In this context, the study of the sensorless control of the Brushless Synchronous Starter Generator (BSSG) that is used to electrically start the main engine is revealed to be a very interesting issue. For long time, the elimination of the mechanical sensor was highly recommended for reliability, cost, weight, integration issues.Hence, this work aims to transpose the results obtained in the research area to an avionic testbench. It presents an adaptive sensorless technique to use when electrically starting the main engine of the aircraft. This is achieved by elaborating three different methods selected depending on the speed of the machine and based on the :- injection of a high frequency signal- use of the back-emf of the Permanent Magnet Generator (PMG)- use of the extended Kalman Filter EKFIn this work, it is shown that the …first method gives good position estimation results from standstill up to 8% of the rated speed. Then, the back-emfs of the PMG are used to detect the position of the BSSG when the speed exceeds the 8% of the rated speed. Good results are observed with this method at medium and high speed.For redundancy reasons, the EKF was also used in this work. Thus, the estimated position can be delivered via two different estimation algorithms in medium and high speed region.The implementation of the algorithm was achieved on an FPGA board since the latter can ensure a very tiny execution time. The fastness of the treatment ensures quasi-instantaneous position estimation and does not practically introduce any phase lag in the position estimationAujourd'hui, l'aviation est en train de vivre des évolutions technologiques concernant surtout l'attribution de différentes fonctionnalités aux équipements électriques et ceci au détriment d'équipements hydrauliques et mécaniques assurant les mêmes fonctionnalités.Dans le cadre de l'avion plus électrique, le démarrage électrique sans capteurs mécaniques de la turbine de l'avion préoccupe les avionneurs de nos jours. Les problèmes introduits par ce capteur ont été identifiés : problèmes de coût et de poids, problèmes de fiabilité et d'intégration.Ce travail présente alors une commande sans capteurs pour la machine synchrone à trois étages à utiliser durant le démarrage électrique de l'avion. Ceci est réalisé avec trois méthodes de détection de la position selon la vitesse de rotation, basées sur :- l'injection d'un signal à haute fréquence- l'utilisation d'un filtre de Kalman étendu FKE- les fém. du PMG (Permanent Magnet Generator) La première méthode donne de bons résultats d'estimation depuis l'arrêt jusqu'à 8% de la vitesse nominale de la machine. Au-delà de cette vitesse, es valeurs des fém. du PMG deviennent assez élevées pour être utilisées dans l'estimation de la position. De bons résultats sont obtenus à moyenne et haute vitesse.Pour des questions de redondance, le FKE est aussi utilisé. Ainsi, la position estimée peut être fournie par l'un des deux algorithmes à moyenne et haute vitesse.L'implémentation de ces algorithmes est réalisée via une carte FPGA étant donné que celui-ci garantit un temps d'exécution. La rapidité de traitement garantit une estimation de la position quasi-instantanée et donc n'introduit pratiquement pas des retards dans l'estimation
38
Prokop, Jan. "Analýza účinků zkratového proudu v rozváděči". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221261.
Abstract (sommario):
The work is focusing on dynamic effects of short-circuit currents, more precisely dynamic effects of short-circuit currents on switchgear cabinet (terminal box). The work was designated to a concrete construction type of two switchgear cabinets located on rotating machines via company Siemens Electric Machines Drásov s.r.o.. The switchgear cabinets are designed for non-explosive environment where the air is used as an insulating medium. The task was to determine how the device will behave during the three-phase short-circuit and three-phase short-circuit with earth/ground connection. The following programs were used for the calculations and simulations: Ansoft Maxwell 16.0, Ansoft Maxwell 2015 and ANSYS Workbench 16.0. By using these programs the effects of forces which acts on current paths in cabinet caused by the passage of short-circuit current were simulated, statically and also dynamically. Further the effects of pressure acting on cabinet frame during the arc short-circuit have been statically and dynamically simulated. All the results are summarized in the conclusion. Conclusion also contains the final evaluation of the functionality of both switchgear cabinets.
39
Procházka, Jan. "Izolační systémy elektrických strojů malého a nízkého napětí". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-399552.
Abstract (sommario):
This thesis describes properties of windings of electric rotating machines and their insulation systems. There are winding and insulation low voltage machines tests listed with their procedures and criteria. Further it deals with coordination methodology and the last part contains execution and results assessment of tests conducted on stator samples.
40
Huang, Ting-cheng, e 黃錠城. "A Simple Partial Discharge Detector for Low-Voltage Rotating Electrical Machines". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/29619747962216661730.
Abstract (sommario):
碩士國立成功大學
電機工程學系碩博士班
95
In this paper, we develop a simple detection circuit which using the acoustic emission (AE) technique to examine partial discharge (PD) signals from low-voltage rotating electrical machines. Most of traditional PD measurement methods use electrical techniques, namely, capacitive coupling (CC), RLC circuit, or high-frequency current transformer (HFCT), to examine the high-frequency electrical signals produced by partial discharge. To reduce the effect of noise from environment and improve the signal-to-noise ratio (SNR), higher frequency detectors are used. However, it means the cost of hardware and instruments will increase. The frequency of signals from AE measurements is in the range from several kHz to hundreds kHz. It is much lower than the signal frequency of electrical methods (several hundred MHz). So, the AE method can substantially reduce the cost of the whole system. In additional, since AE signal is acoustical, it can be easily kept away from the interference of high frequency electrical noises. From the practical experiment results, the measurement system developed in this work can be used to detect the PD-AE signal correctly. When compare with traditional methods, the AE technique exhibits a potential for low-cost PD measurement.
41
Ling-ChihWei e 魏伶芷. "Rotating Electrical Machines Defect Signal Measurement and Analysis Using Acoustic Emission Method". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/mesc7f.
Abstract (sommario):
碩士國立成功大學
電機工程學系
102
In this thesis, an acoustic emission (AE) sensor was used to capture signals from defects in rotating electrical machines. The captured signals are often blurred by noises; therefore, to identify the defect signals, they are differentiated from noise by using wavelet analysis (WA) methods. The signal processing system developed in this study incorporates two types of wavelet analysis methods: the wavelet packet method and wavelet denoise method. In addition, fast fourier transform (FFT) is adopted to obtain the frequency distribution of defect signal data, and the defect signals are displayed in 3D space by using PD patterns. An identification system that can distinguish the defective parts of rotating electrical machines is constructed. The effectiveness of the system is analyzed by comparing the experimentally measured defect signal data from three defective parts of rotating electrical machine (e.g., the rotor, stator and shaft). The consistency of the analysis results is verified by conducting experiments on several rotating electrical machines.
42
(9179804), Daniel Christopher Horvath. "Analysis and Design of Electric Machines Using 2D Method of Moments". Thesis, 2020.
Abstract (sommario):
Recently, researchers have pointed their attention toward Method of Moments (MoM)-based approaches to model low frequency magnetic devices (i.e. transformers and inductors). This has been prompted by the use of population-based design (PBD) methods wherein the performance of large numbers (on the order of millions) of candidate designs must be evaluated. MoM is attractive for such problems due to the fact that only the magnetic material is discretized. In addition, for the case in which the magnetic material is linear, only a surface mesh is required. In this research, point-matching and Galerkin-based MoM formulations are utilized for the design of electric machinery. In the formulations considered, the model inputs are the free currents of machine windings and the bound currents of permanent magnets. The unknowns are the magnetizations within the magnetic material which are used to compute winding inductance, electromagnetic torque, and core loss.
The proposed Galerkin formulation has been utilized in the PBD of a surface-mount permanent magnet machine with favorable results. Specifically, it is shown that a machine's performance can be evaluated on a time scale expected of a practical design tool. This is achieved in part through judicious exploitation of the periodic structure and excitation of machines to reduce the size of the system matrix. It is shown how the exploitation of periodic structure may be extended to the point-matching formulation for use in nonlinear analyses. Finally, alternative hybrid approaches that combine surface and volume meshing are explored for the analysis of an internal permanent magnet machine. It is shown that such a combination holds promise as a tool for rapid evaluation of machine performance.
43
Chen, Jiun-Yo, e 陳俊佑. "Fault Diagnosis Using Electrical Signal for Rotating Electrical Machinery". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/mbntv4.
Abstract (sommario):
碩士正修科技大學
電機工程研究所
100
The thesis proposes artificial neural network (ANN) to a fault diagnosis system for rotor electrical machinery. The operation of machinery will generate mechanical vibration. However, it may be a fault signal when the vibration become abnormal enlarged. The research use rotor perturbation system of rotor machinery to simulate the fault signal and use triaxial accelerometer to measure the signal. The frequency domain signal can be obtained by Fourie transformation. After sorting the eigenvalue of frequency spectrum, the signal can be used as training data for ANN. The current harmonic signal and mechanical vibration signal are used in the thesis to ANN for fault diagnose. The trained ANN is used for diagnosis fault type of rotor machinery. There are 11 fault signal simulated in the thesis by the rotor simulation system for the fault forecasting system. The results show that vibration and current harmonic signal both have excellent diagnosis outcome.
44
Preetha, P. "Studies On Epoxy Nanocomposites As Electrical Insulation For High Voltage Power Apparatus". Thesis, 2012. https://etd.iisc.ac.in/handle/2005/2543.
Abstract (sommario):
High voltage rotating machines play a significant role in generation and use of electrical energy as the demand for power continues to increase. However, one of the main causes for down times in high voltage rotating machines is related to problems with the winding insulation. The utilities want to reduce costs through longer maintenance intervals and a higher lifetime of the machines. These demands create a challenge for the producers of winding insulations, the manufacturers of high voltage rotating machines and the utilities to develop new insulation materials which can improve the life of the equipment and reduce the maintenance cost.
The advent of nanotechnology in recent times has heralded a new era in materials technology by creating opportunities to significantly enhance the properties of existing conventional materials. Polymer nanocomposites belong to one such class of materials that exhibit unique combinations of physical, mechanical and thermal properties which are advantageous as compared to the traditional polymers or their composites. Even though they show tremendous promise for dielectric/electrical insulation applications, there are no studies relating to the long term performance as well as life estimation of the nanocomposites. Considering this, an attempt is made to generate an understanding on the feasibility of these nanocomposites for electrical insulation applications. An epoxy based nanocomposite system is chosen for this study along with alumina (Al2O3) and silica (SiO2) as the nanofillers.
The first and the foremost requirement for studies on polymer nanocomposites is to achieve a uniform dispersion of nanoparticles in the polymer matrix, as nanoparticles are known to agglomerate and form large particle sizes. A laboratory based direct dispersion method is used to process epoxy nanocomposites in order to get well dispersed samples. A detailed microscopy analysis of the filler dispersion using Scanning Electron Microscope (SEM) has been carried out to check the dispersion of the nanofiller in the polymer. An attempt is made to characterize and analyze the interaction dynamics at the interface regions in the epoxy nanocomposite by glass transition temperature (Tg) measurements and Fourier transform infrared (FTIR) spectroscopy studies. The values of Tg for the nanocomposites studied
decreases at 0.1 wt% filler loading and then starts to increase gradually with increase in filler loading. This Tg variation suggests that there is certainly an interaction between the epoxy chains and the nanoparticles. Also no new chemical bonds were observed in the spectra of epoxy nanocomposite as compared to unfilled epoxy. But changes were observed in the peak intensity and width of the –OH band in the spectrum of epoxy nanocomposite. This change was due to the formation of the hydrogen bonding between the epoxy and the nanofiller.
The thermal conductivity of the epoxy alumina and the epoxy silica nanocomposites increased even with the addition of 0.1 wt% of the filler. This increase in thermal conductivity is one of the factors that make these nanocomposites a better option for electrical insulation applications.
The dielectric properties of epoxy nanocomposites obtained in this investigation also reveal few interesting behaviors which are found to be unique and advantageous as compared to similar properties of unfilled materials. It is observed that the addition of fillers of certain loadings of nanoparticles to epoxy results in the nanocomposite permittivity value to be lower than that of the unfilled epoxy over the entire range of frequencies [10-2-106 Hz] considered in this study. This reduction has been attributed to the inhibition of polymer chain mobility caused by the addition of the nanoparticles. The tan 𝛿 values are almost the same or lower as compared to the unfilled epoxy for the different filler loadings considered. This behavior is probably due to the influence of the interface as the strong bonding at the interface will make the interface very stable with fewer defects apart from acting as charge trapping centres.
From a practical application point of view, the surface discharge resistant characteristics of the materials are very important and this property has also been evaluated. The resistance to surface discharge is measured in the form of roughness on the surface of the material caused by the discharges. A significant enhancement in the discharge resistance has been observed for nanocomposites as compared to unfilled epoxy/ microcomposites, especially at longer exposure durations. The partial discharge (PD) measurements were carried out at regular intervals of time and it is observed that the PD magnitude reduced with discharge duration in the case of epoxy alumina nanocomposites. An attempt was made to understand the chemical changes on the surface by conducting the FTIR studies on the aged surface.
For all electrical insulation applications, materials having higher values of dielectric strengths are always desired and necessary. So AC breakdown studies have also been conducted. The AC breakdown strength shows a decreasing trend up to a certain filler loading and then an increase at 5 wt% filler loading for epoxy alumina nanocomposites. It has been also observed that the type of filler as well as the thickness of the filler influences the breakdown strength. The AC dielectric strength of microcomposites are observed to be lower than the nanocomposites.
Extensive research by long term aging studies and life estimation are needed before these new nanocomposites can be put into useful service. So long term aging studies under combined electrical and thermal stresses have been carried out on unfilled epoxy and epoxy alumina nanocomposite samples of filler loading 5 wt%. The important dielectric parameters like pemittivity, tan and volume resistivity were measured before and after aging to understand the performance of the material under study. The leakage current was measured at regular intervals and tan values were calculated with duration of aging. It was observed that the tan values increased drastically for unfilled epoxy for the aging duration considered as compared to epoxy alumina nanocomposites. The life estimation of unfilled epoxy as well as epoxy nanocomposites were also performed by subjecting the samples to different stress levels of 6 kV/mm, 7 kV/mm and 8 kV/mm at 60 oC. It is observed that the epoxy alumina nanocomposite has an enhanced life which is nine times the life of the unfilled epoxy. These results obtained for the nanocomposites enable us to design a better material with improved dielectric strength, dielectric properties, thermal conductivity, resistance to surface discharge degradation and enhanced life without sacrificing the flexibility in the end product and the ease of processing. Dry type transformers and stator winding insulation need to be cast with the above material developed and tested before practically implementing these in the actual application.
45
Preetha, P. "Studies On Epoxy Nanocomposites As Electrical Insulation For High Voltage Power Apparatus". Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2543.
Abstract (sommario):
High voltage rotating machines play a significant role in generation and use of electrical energy as the demand for power continues to increase. However, one of the main causes for down times in high voltage rotating machines is related to problems with the winding insulation. The utilities want to reduce costs through longer maintenance intervals and a higher lifetime of the machines. These demands create a challenge for the producers of winding insulations, the manufacturers of high voltage rotating machines and the utilities to develop new insulation materials which can improve the life of the equipment and reduce the maintenance cost.
The advent of nanotechnology in recent times has heralded a new era in materials technology by creating opportunities to significantly enhance the properties of existing conventional materials. Polymer nanocomposites belong to one such class of materials that exhibit unique combinations of physical, mechanical and thermal properties which are advantageous as compared to the traditional polymers or their composites. Even though they show tremendous promise for dielectric/electrical insulation applications, there are no studies relating to the long term performance as well as life estimation of the nanocomposites. Considering this, an attempt is made to generate an understanding on the feasibility of these nanocomposites for electrical insulation applications. An epoxy based nanocomposite system is chosen for this study along with alumina (Al2O3) and silica (SiO2) as the nanofillers.
The first and the foremost requirement for studies on polymer nanocomposites is to achieve a uniform dispersion of nanoparticles in the polymer matrix, as nanoparticles are known to agglomerate and form large particle sizes. A laboratory based direct dispersion method is used to process epoxy nanocomposites in order to get well dispersed samples. A detailed microscopy analysis of the filler dispersion using Scanning Electron Microscope (SEM) has been carried out to check the dispersion of the nanofiller in the polymer. An attempt is made to characterize and analyze the interaction dynamics at the interface regions in the epoxy nanocomposite by glass transition temperature (Tg) measurements and Fourier transform infrared (FTIR) spectroscopy studies. The values of Tg for the nanocomposites studied
decreases at 0.1 wt% filler loading and then starts to increase gradually with increase in filler loading. This Tg variation suggests that there is certainly an interaction between the epoxy chains and the nanoparticles. Also no new chemical bonds were observed in the spectra of epoxy nanocomposite as compared to unfilled epoxy. But changes were observed in the peak intensity and width of the –OH band in the spectrum of epoxy nanocomposite. This change was due to the formation of the hydrogen bonding between the epoxy and the nanofiller.
The thermal conductivity of the epoxy alumina and the epoxy silica nanocomposites increased even with the addition of 0.1 wt% of the filler. This increase in thermal conductivity is one of the factors that make these nanocomposites a better option for electrical insulation applications.
The dielectric properties of epoxy nanocomposites obtained in this investigation also reveal few interesting behaviors which are found to be unique and advantageous as compared to similar properties of unfilled materials. It is observed that the addition of fillers of certain loadings of nanoparticles to epoxy results in the nanocomposite permittivity value to be lower than that of the unfilled epoxy over the entire range of frequencies [10-2-106 Hz] considered in this study. This reduction has been attributed to the inhibition of polymer chain mobility caused by the addition of the nanoparticles. The tan values are almost the same or lower as compared to the unfilled epoxy for the different filler loadings considered. This behavior is probably due to the influence of the interface as the strong bonding at the interface will make the interface very stable with fewer defects apart from acting as charge trapping centres.
From a practical application point of view, the surface discharge resistant characteristics of the materials are very important and this property has also been evaluated. The resistance to surface discharge is measured in the form of roughness on the surface of the material caused by the discharges. A significant enhancement in the discharge resistance has been observed for nanocomposites as compared to unfilled epoxy/ microcomposites, especially at longer exposure durations. The partial discharge (PD) measurements were carried out at regular intervals of time and it is observed that the PD magnitude reduced with discharge duration in the case of epoxy alumina nanocomposites. An attempt was made to understand the chemical changes on the surface by conducting the FTIR studies on the aged surface.
For all electrical insulation applications, materials having higher values of dielectric strengths are always desired and necessary. So AC breakdown studies have also been conducted. The AC breakdown strength shows a decreasing trend up to a certain filler loading and then an increase at 5 wt% filler loading for epoxy alumina nanocomposites. It has been also observed that the type of filler as well as the thickness of the filler influences the breakdown strength. The AC dielectric strength of microcomposites are observed to be lower than the nanocomposites.
Extensive research by long term aging studies and life estimation are needed before these new nanocomposites can be put into useful service. So long term aging studies under combined electrical and thermal stresses have been carried out on unfilled epoxy and epoxy alumina nanocomposite samples of filler loading 5 wt%. The important dielectric parameters like pemittivity, tan and volume resistivity were measured before and after aging to understand the performance of the material under study. The leakage current was measured at regular intervals and tan values were calculated with duration of aging. It was observed that the tan values increased drastically for unfilled epoxy for the aging duration considered as compared to epoxy alumina nanocomposites. The life estimation of unfilled epoxy as well as epoxy nanocomposites were also performed by subjecting the samples to different stress levels of 6 kV/mm, 7 kV/mm and 8 kV/mm at 60 oC. It is observed that the epoxy alumina nanocomposite has an enhanced life which is nine times the life of the unfilled epoxy. These results obtained for the nanocomposites enable us to design a better material with improved dielectric strength, dielectric properties, thermal conductivity, resistance to surface discharge degradation and enhanced life without sacrificing the flexibility in the end product and the ease of processing. Dry type transformers and stator winding insulation need to be cast with the above material developed and tested before practically implementing these in the actual application.
46
Tsai, Jen-Chen, e 蔡鎮丞. "Fault Diagnosis System Development for Rotating Electrical Machinery". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/00907609306541719105.
Abstract (sommario):
碩士正修科技大學
電機工程研究所
99
The thesis proposes a artificail neural network(ANN) for rotor machinery fault diagosis system. The fault detection is important for the the electrical rotor machinery. The breakdown of the rotor electrical machinery, especially the important machines, will bring about interruption of production and reduce profits. If there is a predictive fault diagnosis system, the situation of the outage can be avoided. However, the components of the rotor machinery are more complex and more sophisticated recently. These causes resulting in the machine vibration problems become more various and complicated. The mechanical vibration signal is a major parameter for the predictive maintenance system. The subject draws much attention in the predictive detection research. However, the electrical signal is also an important response when the electrical rotor machinery is breakdown. The thesis propose a excellent fault detection method, which is not only vibration signal considered but also electrical signal. The ANN is used to forecast for the fault diagnosis system in the study. The operation situation of machine can be detected by the parameters of operational pressure, temperature, and vibration. The thesis, also proposes the input current of machinery for more precisely diagnosing the equipment operation situation. These parameters are used to set the training patterns for the ANN to develop the fault diagnosis systems. Keywords: rotor electrical machinery, fault diagnosis, artificial neural network
47
Hsieh, Chun-Nan, e 謝俊男. "Teaching Evaluation and Development of Teaching Aidsfor Rotating Electrical Machinery". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/98540020202718802276.
Abstract (sommario):
碩士國立宜蘭大學
電機資訊學院碩士在職專班
102
This thesis is develops a set of innovative teaching aids for rotating electrical machinery. This device is based on an innovative concept that substitutes “Pulsed DC power supply” for the “AC source”. In manual operation mode, we break down the “continuous” rapid action of rotating electrical machinery into the “discrete” step-by-step manual operation mode. Through hands-on operations, students get to know the principles of motor actions step-by-step. We used permanent magnet as rotor and constructed stators with six coils. Three sets of coils must be mutually spaced at 120 degree intervals. Divided one AC sinusoidal period into 12 working sectors, so that each sector has 30 degree. Replaced the three-phase sine wave ac power with three-phase square wave ac power, making it easier to explain the model, given that the three-phase square wave power has three different output voltage levels. When the stator coil is connected to three phase pulsed DC power supply, it generates a magnetic field, causing the rotor to rotate. In actual operation, the motor simulation device could speed up to 2000 rpm. This project utilized two different colors of LED to represent the directions of magnetic lines of force and to indicate the magnetic field generated by the stator coil. Students can take advantage of the LED light changes to understand how the three-phase coil established a rotating magnetic field. The colorful blinking LED lights can effectively attract students' attention and significantly enhance their learning motivation and efficiency. This LED motor model could be used in vocational schools and universities and would be of great assistance in electric machinery courses and personnel training.
48
CHU, HUNG-SHIN, e 朱宏昕. "Modeling of Electric Energy Decoupling in Rotating Machine and the Controller Design". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/z48246.
Abstract (sommario):
碩士國立虎尾科技大學
電機工程系碩士班
106
Nowadays, the power conversion system module is an indispensable important block for electric machinery vehicles. In the research, the different power converters have many similar active and passive components. With proper topology design and control laws, the size and cost of the whole system could be effectively reduced. This thesis based on the multi-voltage source voltage node switching analysis and switching unit matrix, systematically integrates different conversion architectures into a single system and uses motor inductance as a shared component in the power conversion system. In the electric energy conversion system, when the motor winding is used as a shared component, torque effects such as Electric Energy To Mechanical (ETM) and Electric Energy To Electricity (ETE) are generated. This thesis is mainly analysis and development of electric energy decoupling control method for ETM, combined with the electrical energy conversion mode of the composite electric energy system topology, can replace the mechanical jig hardware used to fix the motor rotor. Finally, the feasibility of this control method was verified by experiment.
49
Lin, Shang-Chih, e 林上智. "Study on Fuzzy Theory-Based Fault Diagnosis and Condition Monitoring Systems for Rotating Electrical Machine". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/839j53.
Abstract (sommario):
博士國立臺灣科技大學
電機工程系
104
Thanks to the rapid development of science and technology, artificial intelligence has been widely used in various industries, the fourth industrial revolution has quietly come, the rotating electrical machine is the mother of industry, plays a pivotal role in the power grid and plants, and predict maintenance strategy is now of concern important operation and maintenance issues, therefore, put forward a fuzzy theory-based fault diagnosis and condition monitoring systems for rotating electrical machine, which will help to enhance the reliability of the unit stable operation. In this study, a total of ten rotating electrical machine for an experimental model to make electrical, vibration and partial discharge signal analysis, and the use of data mining technology in the mining potential of the signal fault symptoms, according to different considerations of cost and safety factors are proposed five kinds of fault diagnosis and three states monitoring system solutions. The experimental model test results, 52 % of the electrical method with the highest probability of accurately infer broken rotor bar fault, vibration method to 100 % of the highest probability of accurately infer the bearing outer ring damage and eccentric failure, partial discharge method with the highest probability of 100 % accurately infer the stator insulation failure. However, hybrid electric and vibration method can effectively improve the broken rotor bars inference probability to 83 %, and then integrate the partial discharge method, can be more accurately identification of stator insulation type of exception, and effectively avoid the possibility of misjudged, electrical, vibration and partial discharge of condition monitoring systems, taking into account relevant monitoring programs, such as the gap spacing and failure factors, and strengthening existing international standards-based condition monitoring guidelines, but in the future remains to be done to monitor the long-term operation of the rotating electrical machine, according to data analysis adjustment inference rule and the weight values to expect substantive enhance monitoring performance and operation reliability. Concluding our proposed rotating electrical machine operation and maintenance strategy confirmed by experiments with the feasibility and effectiveness. We look forward to a positive helpful in the development process of the domestic industry, and further to avoid rotating motor abnormalities lead to serious negative impact on casualties and economic losses.
50
Wang, KeSheng. "Vibration monitoring on electrical machine using Vold-Kalman filter order tracking". Diss., 2008. http://hdl.handle.net/2263/27613.
Abstract (sommario):
Conventional rotating machine vibration monitoring techniques are based on the assumption that changes in the measured structural response are caused by deterioration in the condition of the rotating machine. However, due to changing rotational speed, the measured signal may be non-stationary and difficult to interpret. For this reason, the order tracking technique was introduced. One of main advantages of order tracking over traditional vibration monitoring techniques, lies in its ability to clearly identify non-stationary vibration data, and to a large extent exclude the influences from varying rotational speed. Several order tracking techniques have been developed and researched during the past 20 years. Among these techniques, Fourier Transform Based Order Tracking (FT-OT), Angle Domain Sampling Based Order Tracking (AD-OT) and Vold-Kalman Filter Order Tracking (VKF-OT) are the three most popular techniques and have been commercialised in software. While the VKF-OT is comparatively new, and both its theory and application are different from the other two techniques, the unique advantages of this technique has led to increased research attention in this field. This growing interest in research on the application of the VKF-OT technique on real machines, and its comparative advantages with respect to other order tracking techniques, inspired the present research. With this work, a comprehensive literature of electrical machine condition monitoring was surveyed, which gives a broad perspective of electrical machine monitoring methods ranging through electrical techniques, vibration techniques, temperature techniques and chemical techniques. To simply the process of applying VKF-OT in initial investigations, simulated single-degree-of freedom and two-degree-of freedom rotor models were established, and the application of the VKF-OT technique on these simulated models was explored. Because most of the current research draws significantly on an understanding of the VKF-OT theory, it was also necessary to review and summarize the current status of VKF-OT theory from previous work, as well as explore the procedures for selection of its filter bandwidth when dealing with real data. An experimental set-up for monitoring an electrical alternator was constructed. Real experimental data were subsequently used to compare the advantages and disadvantages of the three popular order tracking techniques. The unique time domain advantage of VKF-OT was implemented, using crest factor and kurtosis values as indictors of the fault condition of the machine. This gave encouraging results.Dissertation (MSc)--University of Pretoria, 2008.
Mechanical and Aeronautical Engineering
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