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Dans le cadre de la réduction des émissions des gaz à effet de serre, et devant l'augmentation incessante du prix de l'énergie, la course à l'amélioration des performances énergétiques touche tous les secteurs : industriel, tertiaire ou même celui des particuliers. La consommation de l'énergie électrique est due en grande partie aux moteurs électriques, et particulièrement les machines asynchrones, utilisées dans diverses applications telles que le pompage, la ventilation ou la compression. Ces machines sont caractérisées par des rendements relativement faibles et leur remplacement par des machines plus performantes permettrait un gain d'énergie non négligeable. Les machines à aimants permanent ayant pouvoir de démarrage autonome sont de bonnes candidates pour répondre à ce besoin. Elles ont de très bons rendements et les artifices supplémentaires permettant le démarreur automne suppriment la nécessité d'utiliser des convertisseurs statiques comme dans le cas des machines à aimants classiques. Des contraintes spécifiques se posent cependant pour l'utilisation et le dimensionnement de ces machines : en effet, le courant de démarrage ne doit pas être trop important à cause du risque de démagnétiser les aimants et le couple de démarrage doit être suffisamment grand pour assurer un démarrage en charge. Par ailleurs les rendement et facteurs de puissance en pleine charge doivent être assez nettement supérieurs à ceux des machines asynchrones pour les rendre plus compétitives. Dans cette thèse, nous étudions trois structures de rotor permettant de répondre à un cahier des charges donné. Ces trois structures utilisent des aimants en surface, insérés dans un rotor massif ou dans un rotor à cage. Elles ont leurs avantages et leurs inconvénients, que nous avons mis en évidence par une étude comparative assez détaillée. Cette étude comparative n'a pu être mise en oeuvre sans l'établissement de modèles en régime statique ou dynamique de ces machines ou encore de méthodologie de conception. Un prototype à échelle réduite a été dimensionné, réalisé et testé au laboratoire ; il confirme les principes de base de ce type de machines / In the context of reducing emissions of greenhouse effect, and of energy cost, the competition to improve the performances of the equipments affects all the domains. The consumption of electricity is mostly due to the electric motors, and particularly induction machines, used in various devices such as pumps, fans or compressors. These machines are characterized by relatively low efficiencies, and their replacement by more efficient machines should lead to a significant power saving. The Line-Start Permanent Magnet motors are good candidates to achieve this purpose. They have higher efficiencies and the additional devices for self-start eliminates the need of static converters, as it is normally required for conventional permanent magnet motors. Specific constraints arise for the use and the design of these machines: the starting current should not be so high to avoid the risk of the demagnetization of magnets and the starting torque must be large enough to ensure the start under load. Moreover, the efficiency and power factor at full load must be sufficiently higher than those of asynchronous machines in order to make them more competitive. In this thesis, we study three rotor structures to meet a given specification. These three structures use magnets inserted on the surface, embedded in a solid rotor or a cage rotor. They have their advantages and drawbacks that we have shown by a comparative study in some detail. This comparative study could not be implemented without the development of models in both static and dynamic conditions of these machines and a specific design methodology. A small scale of prototype has been designed, built and tested in the laboratory; it confirms the basic principles of such machines

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Slip-synchronous permanent magnet generators (SS-PMG) is a recently proposed direct-grid connected direct-drive generator topology for wind power applications. It combines a permanent magnet synchronous generator and a slip permanent magnet generator through a common permanent magnet rotor. In this study the possibility of using an eddy current coupling as the slip permanent magnet generator is investigated. The eddy current coupling has the attractive advantage of completely removing cogging and load torque ripple, which are known problems in the SS-PMG. However, the analytical modelling of the eddy current coupling is complex. Three different topologies are considered for the eddy current coupling. A finite element model is presented for the eddy current coupling. It is shown that 2D finite element methods are inaccurate compared to 3D finite element methods when solving eddy currents in eddy current couplings. In order to test the accuracy of the finite element modelling of a large eddy current coupling a prototype slip rotor is designed to operate with an existing permanent magnet rotor. Two topologies are optimally designed and compared for the slip rotor, using 3D finite element transient simulations. One of the designed topologies is used for the construction of the prototype slip rotor. The manufactured eddy current coupling allows for comparison between the 3D finite element simulations and measured results, which shows an excellent correlation. Based on observations of the 3D finite element simulations an analytical approximation of the eddy current coupling is proposed for low slip frequencies. It is shown that the analytical model is very dependent on the accurate modelling of the eddy current paths in the slip rotor, something that is difficult to determine accurately. An approximation is made, again based on 3D finite element simulations, which allows the accurate modelling of the current paths for different axial lengths. The analytical model is used for rapid design optimisation of both the slip rotor and permanent magnet rotor of the eddy current coupling, for two different eddy current coupling topologies. The optimised eddy current coupling design with the best results is compared to existing slip permanent magnet generator technologies. The eddy current coupling is shown to have the potential to be a feasible alternative to existing slip permanent magnet generator topologies for application in slip-synchronous permanent magnet generators. It has excellent torque versus slip behaviour, and no cogging or load torque ripple. However, the manufacturing and assembly process of the proposed slip rotor has to be improved for the eddy current coupling to be a realistic competitor to the existing slip permanent magnet generator technologies. / AFRIKAANSE OPSOMMING: Die glip-sinkroon permanente magneet generator is ʼn direk-aangedrewe wind generator wat direk aan die krag netwerk gekoppel kan word. Dit kombineer ʼn permanente magneet sinkroon generator en ʼn permanente magneet glip generator deur middel van ʼn gemeenskaplike permanente magneet rotor. In hierdie studie word die moontlike gebruik van ʼn werwelstroom skakel as plaasvervanger vir die permanente magneet glip generator ondersoek. Die werwelstroom skakel het geen vertandings of las draaimoment rimpeling nie, wat bekende probleme vir die glip-sinkroon permanente magneet generator is. Die analitiese modellering van die werwelstroom skakel is egter nie eenvoudig nie. Daar word drie verskillende topologieë oorweeg vir die werwelstroom skakel. ʼn Eindige element model word ontwikkel vir die werwelstroom skakel. Dit word bevind dat 2D eindige element analise onvoldoende is vir die berekening van werwelstrome in die werwelstroom skakel, en gevolglik word 3D eindige element modelle gebruik in hierdie studie. Om die akkuraatheid van die eindige element model te beproef word ʼn prototipe glip rotor optimaal ontwerp deur middel van eindige element analise. Die glip rotor vorm saam met ʼn bestaande permanente magneet rotor ʼn werwelstroom skakel. Vir hierdie ontwerp word twee werwelstroom skakel topologieë gebruik, en met mekaar vergelyk. Die topologie wat beter presteer word gebruik vir die vervaardiging van die glip rotor. ʼn Vergelyking van die gemete waardes van die vervaardigde werwelstroom skakel en die resultate van die 3D eindige element simulasies dui daarop dat die 3D eindige element modellering ʼn baie goeie voorspelling van die werklikheid is. ʼn Analitiese model vir die werwelstroom skakel onder lae glip toestande is ontwikkel deur gebruik te maak van observasies uit die 3D eindige element simulasies. Die analitiese model is baie afhangklik van die modellering van die werwelstrome se stroompaaie, iets wat moeilik is om akkuraat te bepaal. ʼn Benadering word gemaak wat die akkurate modulering van die stroompaaie moontlik maak vir verskillende aksiale lengtes. Die analitiese model word dan gebruik vir vinnige optimering van die werwelstroom skakel se ontwerp vir twee verskillende werwelstroom skakel topologieë. Die geoptimeerde ontwerp wat die beste resultate toon word vergelyk met bestaande permanente magneet glip generators. Dit word gewys dat die werwelstroom skakel die potensiaal het om ʼn uitvoerbare alternatief tot die permanente magneet glip generator te wees, vir gebruik in glip-sinkroon permanente magneet generators. Die werwelstroom skakel toon baie goeie draaimoment teenoor glip gedrag, en het geen vertandings of las draaimoment rimpeling nie. Voordat die werwelstroom generator ʼn realistiese kompeteerder teenoor die bestaande glip-sinkroon tegnologie is, moet daar verbeterde vervaardigings maniere gevind word vir die voorgestelde glip rotor.

Master’s thesis summs up issues of mounting pemanent magnets on rotor surface of permanent magnet synchronous machine. Literature reseach is divided in two parts. First one shows studies and experiments researching the impact of manufacturing tolerances of permanent magnets and wrong mounting on the rotor on cogging torque . The second part focus on analytical aproach of defining influence of permanent magnets on magnetic flux density in the air gap and phase induced voltage. Practical part focus on design of a prototype machine, wich will be used to research the impact of tolerances and imperfections. Parametric model of the prototype machine is created in Maxwell and is subjected to analysis via finite element method. Three different analysis were run, offset of permanent magnet, decrease and wrong dicertion of magnetization. At last the result of cogging torque and induced voltage are compared.

In diesem Beitrag wird eine fertigungsoptimierte Methode der Nutrastmomentreduzierung durch Magnetverschiebung am Beispiel eines Synchrongenerators für Kleinwindenergieanlagen mit in die Läuferoberfläche eingelassenen Permanentmagneten vorgestellt. Auf Grundlage der Drehfeldtheorie wird ein analytisches Berechnungsmodell unter Einbezug der Magnetverschiebung zur Bestimmung des Nutrastmoments entwickelt und mit FEM-Simulationen verifiziert. Durch experimentelle Untersuchung eines gefertigten Prototyps wird der optimierende Effekt der Magnetverschiebung nachgewiesen und mit einem Referenzläufer mit ungeschrägt, symmetrisch verteilten Polen verglichen. Abschließend werden mögliche Ursachen für die verbleibenden Abweichungen identifiziert und Ansätze für die weiteren Betrachtungen abgeleitet. / A production-optimized method of reducing cogging torque by magnet shifting using the example of a synchronous generator for small wind turbines with a rotor with inset surface magnets is proposed in this paper. On the basis of rotating field theory an analytical calculation model is developed taking into account the magnet shifting for determination of cogging torque. The analytical results are verified with FEM simulations. By experimental investigation of a manufactured prototype, the optimizing effect of magnet shifting is verified and compared to a rotor with symmetrically distributed poles. Finally, possible reasons for remaining discrepancies are identified and approaches for further considerations are presented.

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The dissertation thesis deal with the design and the optimization of the permanent magnet synchronous machine (SMPM) based on the artificial intelligence. The main target is to apply potential optimization methods on the design procedure of the machine and evaluate the effectiveness of optimization and the optimization usefulness. In general, the optimization of the material properties (NdFeB or SmCo), the efficiency maximization with given nominal input parameters, the cogging torque elimination are proposed. Moreover, the magnet shape optimization, shape of the air gap and the shape of slots were also performed. The well known Genetic algorithm and Self-Organizing migrating algorithm produced in Czech were presented and applied on the particular optimization issues. The basic principles (iterations) and definitions (penalty function and cost function) of proposed algorithms are demonstrated on the examples. The results of the vibration generator optimization (VG) with given power 7mW (0.1g acceleration) and the results of the SMPM 1,1kW (6 krpm) optimization are practically evaluated in the collaboration with industry. Proposed methods are useful for the optimization of PM machines and they are further theoretically applied on the low speed machine (10 krpm) optimization and high speed machine (120 krpm) optimization.

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