Dissertations / Theses on the topic 'Electrical machine with a solid rotor'

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Certain types of electric machines are particularly susceptible to the proliferation of eddy currents flowing within the solid conducting regions in the rotor. Single-layer, non-overlapping windings within uneven open slots are some stator properties that can produce damaging, asynchronous magnetic field harmonics which manifest in the rotor as eddy currents. The ohmic losses caused by these eddy currents are a source of inefficiency and can cause a marked increase in the temperature of the rotor. This temperature rise can be dangerous for the magnets, which have to be kept within temperature limits to avoid partial or full demagnetization. The research work presented here is concerned with reducing the effect of eddy currents in the rotor magnets and solid rotor yoke of an electric machine. The work presents analytical methods to calculate the magnetic fields, eddy currents and solid loss in an electric machine due to current in the winding and due to the interaction of the permeance variation in the stator with the magnets in the rotor. A method is also suggested where the analytical theory can be used with a magnetostatic finite element solution to produce a transient solid loss result. The research work also investigates a method for optimal segmentation in both level and penetration, and provides some design suggestions. The work presents the method of partial magnet segmentation, which is a technique whereby thin incisions are made into the magnet material from one or both sides. Another method of partial rotor segmentation is also presented where the incisions are made into a portion of the magnet-facing solid yoke. These methods attempt to interrupt the flow of eddy currents and increase the resistance ‘seen’ by the eddy currents, while also keeping construction difficulty and cost to a minimum. The methods are verified using finite element calculations which are compared to measured results. The result is that partial magnet segmentation is a very useful, effective and practical method of segmenting magnets. The loss reduction profile can be similar to that of traditional full segmentation. The method of partial rotor segmentation also shows a large reduction in rotor power loss. With implementation of these methods on a test machine, one can expect an efficiency increase of more than 4 %
AFRIKAANSE OPSOMMING: Sekere tipes van elektriese masjiene is veral sensitief vir die vloei van werwelstrome in solied geleidende gebiede in die rotor. Enkellaag, nie-oorvleuelende wikkelings in oneweredige oop gleuwe is enkele stator eienskappe wat skadelike, asinchrone magneetveld harmonieke tot gevolg kan hê, wat as werwelstrome in die rotor manifesteer. Die ohmiese verliese wat deur hierdie werwelstrome teweeg gebring word is 'n bron van ondoeltreffendheid en kan lei tot 'n merkbare toename in die temperatuur van die rotor. Hierdie temperatuur styging hou gevaar in vir die magnete en moet binne temperatuur limiete gehou word om gedeeltlike of self volle demagnetisering te vermy. Die navorsing vervat in hierdie document is gemoeid met die vermindering van die effek van werwelstrome in die rotor magnete en in die soliede rotor juk van 'n elektriese masjien. Die werk bied analitiese metodes aan vir die berekening van die magneetvelde, werwelstrome en soliede verliese in ’n elektriese masjien as gevolg van strome in die wikkelings en die interaksie van die permeansie variasie van die stator met die magnete in die rotor. ’n Metode word ook voorgestel waar die analitiese teorie saam met ’n magnetostatiese eindige element oplossing gebruik word om ’n resultaat vir die oorgang soliede verliese te verkry. Die navorsingswerk ondersoek ook ’n metode vir die optimale segmentering in beide vlak sowel as penetrasie, en verskaf sekere ontwerp voorstelle. Die werk bied die metode aan van gedeeltelike magneet segmentering, wat 'n tegniek is waarvolgens dun insnydings gemaak word aan een of beide kante van die magneet materiaal. Nog ’n metode van gedeeltelike rotor segmentering word beskou waar die insnydings in in ’n gedeelte aan die magneetkant van die soliede rotor juk gemaak word. Hierdie metodes poog om die vloei van werwelstrome te onderbreek en die weerstand soos "gesien" deur die werwelstrome te verhoog, terwyl konstruksie kompleksiteit en koste tot ’n minimum beperk word. Die metodes word bevestig deur eindige element berekeninge wat met gemete resultate vergelyk word. Die gevolg is dat gedeeltelike magneet segmentering 'n baie nuttige, doeltreffende en praktiese metode van die segmentering van magnete is. Die verliesverminderingsprofiel van gedeeltelike segmentering kan soortgelyk wees aan dit van tradisionele volle segmentering. Die metode van gedeeltelike rotor segmentering toon ook 'n groot afname in rotor drywingsverlies. Met die implementering van hierdie metodes op ’n toetsmasjien, kan ’n mens ’n verhoging in benuttingsgraad verwag van meer as 4 %

Solid rotor induction machines are suitable for applications which require robustness, reliability and high rotational speed. A literature review of high speed technologies is initially presented. The current limitation and challenges are detailed based on a wide collection of data. The multi-physics aspect related with electrical machines for high speed applications are discussed providing a summary of the current state of the art. The main aim of the research was to develop a multi-physic computational environment for the design and analysis of solid rotor induction machines. The electromagnetic, thermal, structural and rotor dynamics models have been developed targeting reduced computational time and accurate predictions. Numerical techniques are proposed based on the discretisation of the computational domain. The different disciplines are linked together providing a flexible and powerful tool for the characterisation of solid rotor induction machine. Another objective was to investigate the impact of the rotor material on the electromagnetic performances of the machine. Finite Element simulation are used to account for the non linear magnetic properties. The impact on the equivalent circuit parameter is discussed and general criteria for material selection presented. Three dimensional finite element calculation are p erformed targeting the validation of the end region correction factor and select the rotor length. The performances of a 120 [kW]−25000 [rpm] solid rotor machine are compared with a caged rotor induction machine for waste heat recovery application.

Dans un but d'augmenter la puissance volumique des machines électriques, et grâce au développement de l'électronique de puissance, les industriels cherchent à construire des machines à grande vitesse de rotation. Un tour d'horizon des différentes technologies envisageables pour de telles applications est présenté. Pour des raisons autant économiques que pratiques, notre choix s'est porté sur la machine asynchrone à rotor massif. L'inexistence de schéma équivalent classique et la volonté d'optimiser les paramètres géométriques du rotor imposent l'utilisation de méthodes numériques. Le calcul par éléments finis du comportement électromagnétique d'une machine asynchrone (classique ou rapide) au régime établi est très consommateur de temps et de mémoire. En effet, les simulations pas à pas dans le temps peuvent durer jusqu'a 200 heures suivant le matériel informatique utilisé. Une nouvelle modélisation est proposée, fondée sur la séparation du domaine d'étude en deux (rotor+entrefer et stator+entrefer) et sur un couplage de ces derniers par le premier harmonique d'espace de la représentation complexe du potentiel vecteur magnétique dans l'entrefer. Le calcul est réalisé en trois étapes successives pour un temps de une à cinq minutes suivant le nombre de nœuds des maillages rotor et stator. Cette méthode de calcul est validée par la comparaison de ses résultats (couple, puissance, courant, tension, glissement) avec les mesures expérimentales effectuées sur une machine réelle. Enfin, des études de machines asynchrones à rotor massif sont présentées

Tato diplomová práce se zabývá elektromagnetickou analýzou a modelováním asynchronního stroje s plným rotorem. Tato práce tedy zahrnuje literární rešerši na téma vysokootáčkových elektrických strojů s porovnáním s klasickými elektrickými stroji s převodovkou a popisem jejich výhod či nevýhod, rozdělení vysokootáčkových elektrických strojů s plnými rotory a srovnání jejich výhod či nevýhod, kde se tato práce nejvíce soustřeďuje na vysokootáčkové asynchronní stroje s plnými rotory a jejich použití v průmyslu. Dále se tato práce zabývá metodami výpočtu elektrických asynchronních strojů s plnými rotory. Proto jsou zde uvedeny a popsány metody výpočtu stroje mezi které patří analytické metody i metoda konečných prvků. Vzhledem k povaze elektrických strojů s plnými rotory je hlavně kladen důraz v této práci na výpočet stroje pomocí metody konečných prvků ve 2D prostoru s využitím korekčních činitelů konců plných rotorů, které jsou zde velmi detailně popsány a rozděleny. Na základě dostupné literatury je vypočítaný elektrický stroj s plným rotorem pomocí MKP analýzy. Elektromagnetický výpočet stroje je automatizován pomocí skriptu vytvořeného v Pythonu. Dalším hlavním cílem této práce je popis tzv. náhradních modelů, uvedení jejich výhod či nevýhod, použití v jiných průmyslových odvětvích a hlavně použití náhradních modelů na elektrický stroj s plným rotorem. S využitím náhradních modelů je dále optimalizovaný vybraný asynchronní stroj s plným rotorem a to pomocí programů SymSpace a Optimizer. Pro samotnou optimalizaci byly uvažovány 3 návrhy stroje, které byly na závěr mezi sebou porovnány a to hlavně z hlediska jejich elektromagnetického výkonu.

The thesis work described in this report is about simulation of the cooling of an electrical machine rotor. Limitations and simplifications were made on the CAD model of the rotor with the purpose of reducing the simulation time, for it to then be used for CFD-simulations using STAR-CCM+. This was done to see the temperature, as well as its distribution, in the model. By changing various parameters, one at the time whilst the rest were kept at their assigned standard values, the changes could be analysed and thereafter compared. The tests include smaller geometry changes, parameters of the coolant and its flow, parameters for the airgap and the materials in the laminates and the material around the magnets, as well as changes in loss values. The simulations for geometry changes involving the magnets and their surrounding material resulted in minor temperature increases. An inner rotor radius increase gave a relatively large temperature decrease (although this change would be more difficult to make in practice). Most of the mean values of the temperature changes in the regions of the model were within 10% from the standard simulation used. Increased thermal contact resistance between the Bakelite and the laminates, and increased losses had the worst impact on the cooling. Meanwhile the changes in coolant parameters (as well as the its inlet temperature and mass flow) and reduced losses had the best impact on the cooling. Generally, the temperature distributions looked similar for the different simulations. There were more differences in the distributions for the simulations with changed material properties or thermal contact resistance.
Examensarbetet som beskrivs i denna rapport handlar om simulering av kylningen av en elmaskinsrotor. Avgränsningar och vissa förenklingar gjordes på en CAD modell av rotorn för att reducera simuleringstiden. Sedan användes CFD-simuleringsprogrammet STAR-CCM+ för att simulera temperaturfördelningen i modellen. Genom att ändra olika parametrar, en åt gången medan resten hölls vid sina bestämda standardvärden, kunde förändringarna undersökas och sedan jämföras. Det som testades inkluderar bland annat mindre geometriförändringar, parametrar för kyloljan och dess flöde, parametrar för luftgapet och materialen i laminaten och runt permanentmagneterna, samt förlustförändringar. Geometriförändringarna som gjordes för magneterna och det omgivande materialet gav små temperaturökningar. En ökad inre radie på rotorn gav relativt stor temperaturminskning (men denna ändring vore svårare att genomföra på rotorn i praktiken). Majoriteten av medelvärdena av modellregionernas temperaturförändringar var inom 10% från standardsimuleringen som användes. Ökat termiskt kontaktmotstånd mellan Bakeliten och laminaten samt ökade förluster hade sämst påverkan för kylningen, medan förändring i kylvätskans egenskaperna (samt inflödestemperaturen och massflödet) samt minskade förluster hade bäst inverkan. Generellt så såg temperaturfördelningarna lika ut för de olika simuleringarna. Det var främst när materialegenskaperna eller det termiska kontaktmotståndet ändrades som fördelningen såg annorlunda ut.

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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.

Thesis (MEng)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: This thesis deals with different design aspects of the multi-flux barrier rotor of the reluctance synchronous machine (RSM). The effect of the different designs on the performance of the RSM is investigated by means of two-dimensional finite element analysis. The finite element analysis is also directly used in the optimum design of the rotor of the RSM. The importance of the use of the finite element analysis in the design and performance calculations of the RSM is illustrated in this thesis. The design aspects of the RSM which are focussed on in this thesis are, amongst other things, the chording of the stator winding, the skewing of the rotor and the ratio of the number of rotor flux barriers to the number of stator slots of the RSM. The effects of these design aspects on the average torque and torque ripple of the RSM are investigated and general design directives are given. The occurrence of flux pulsations in the stator teeth and rotor iron segments of the RSM are also studied to some extent. The finite element optimum design of a4-pole RSM-rotor with a high number of flux barriers is described in the thesis. This optimum designed rotor is built and the RSM with this rotor is tested in the laboratory. Its calculated and measured performances are studied and compared with a conventional, low number rotor flux barrier RSM. It is found, amongst other things, that the RSM with the high number of rotor flux barriers has a slightly higher average torque with a significantly lower torque ripple.
AFRIKAANSE OPSOMMING: Hierdie tesis handeloor verskillende ontwerp-aspekte van die reluktansie sinchroonmasjien (RSM) met 'n multi-vloedversperringsrotor. Die effek van die verskillende ontwerpe op die vermoë van die RSM is met behulp van twee-dimensionele eindige element analise ondersoek. Die eindige element analise is ook direk in die optimum ontwerp van die rotor van die RSM gebruik. Die belangrikheid van die gebruik van die eindige element analise in die ontwerp en vermoë-berekening van die RSM word in die tesis geïllustreer. Die ontwerp-aspekte van die RSM waarop in hierdie tesis gefokus word, is onder andere die spoelsteekverkorting van die statorwikkeling, die skuinsing van die rotor en die verhouding van die getal rotor-vloedverperrings tot die getal statorgIeuwe van die RSM. Die effek van hierdie ontwerpaspekte op die gemiddelde draaimoment en draaimoment-rimpel van die RSM word ondersoek en algemene riglyne vir die ontwerp van die RSM word gegee. Die voorkoms van vloedpulsasies in die statortande en rotor yster segmente van die RSM word ook deels ondersoek. Die eindige element optimum ontwerp van 'n 4-pool RSM-rotor met 'n hoe getal vloedversperrings word in die tesis beskryf. Hierdie optimum ontwerpte rotor is gebou en die RSM met hierdie rotor is in die laboratorium getoets. Die berekende en gemete vermoë is bestudeer en vergelyk met die vermoë van 'n RSM met 'n konvensionele, lae getal vloedversperrings rotor. Dit is onder andere gevind dat die RSM met die hoë getal rotor-vloedversperrings 'n effens hoër gemiddelde draaimoment het met 'n behuidende laer draaimoment-rimpel.

Thesis (MScEng)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: The thesis describes the optimum rotor design and performance of a 110kW Permanent-Magnet assisted (PM-assisted) Reluctance Synchronous traction Machine (RSM) using bonded permanent magnet sheets. Particular attention is given to the performance of the machine drive in the flux-weakening speed region. A detail explanation is given of the finite-element design optimisation, the basic principles of operation and the control-design of the PM-assisted RSM drive. A theoretical torque comparison of the PM-assisted RSM, the standard RSM and the induction machine is also done. The measured and calculated results of the different drives are presented and analysed in detail. It is concluded that the performance of the PM-assisted RSM in terms of torque, voltage and power factor compares favourably well with that of the induction machine in both the constant torque and flux-weakening speed regions. Furthermore, it is shown that the temperature rise of the stator winding of the PMassisted RSM is lower than that of the RSM with both machines at the same load.
AFRIKAANSE OPSOMMING: Die tesis beskryf die optimum rotor ontwerp en vermoë van 'n 110 kW Permanent- Pagnet-ondersteunde (PM-ondersteunde) Reluktansie Sinchroon Masjien (RSM) trekkrag aandryfstelsel. Spesifieke aandag word gegee aan die vermoë van die aandryfstelsel in die vloedverswakking spoedgebied. 'n Volledige verduideliking word gegee van die eindige-element ontwerp optimering, die basiese beginses van werking en die beheer-ontwerp van die PM-ondersteunde RSM aandryfstelsel. 'n Teoretiese vergelyking van die draaiumoment-vergelyking van die PM-ondersteunde RSM, die standard RSM en die induksmasjien word gedoen. Die berekende en gemete resultate van die verskillende aandryfstelsels word in detail aangebied en ge-analiseer. Dit is gevind dat die vermoë van die PM-ondersteunde RSM in terne van draairnoment, spanning en arbeidsfaktor gunstig vergelyk met dit van die induksiemasjien in beide die konstante draairnoment en vloedverswakking spoedgebiede. Verder word getoon dat die temperatuur-styging van die statorwinding van die PM-ondersteunde RSM laer is as die van die RSM, met deide masjiene by die selfde las

Thesis (PhD)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: In this dissertation a new type of electrical machine, a Radial Flux Air-Cored Permanent Magnet machine with a Double-sided Rotor and utilising concentrated, non-overlapping windings, is proposed. The concept of the Double-sided Rotor Radial Flux Air-Cored Permanent Magnet machine, or RFAPM machine for short, was derived from the Double-sided Rotor Axial Flux Air-Cored Permanent Magnet (AFAPM) machine. One of the problems that AFAPM machines experience, is the deflection of the rotor discs due to the strong magnetic pull of the permanent magnets, especially with double-sided rotor machines. The main advantage of a RFAPM machine over a AFAPM machine is that the rotor back-iron is cylindrically shaped instead of disk shaped. Due to the structural integrity of a cylinder, the attraction force between the two rotors does not come into play any more. The focus of this dissertation is on a thorough analytical analysis of the Double-Sided Rotor RFAPM machine. With the RFAPM being an air-cored machine, the feasibility to develop a linear, analytical model, to accurately predict the radial flux-density and hence the induced EMF in the stator windings, as well as the accurate calculation of the developed torque of the machine, needed to be investigated. The need for a thorough analytical examination of the Double-Sided Rotor RFAPM machine stemmed from the need to reduce the blind reliance on Finite Element Modelling (FEM) software to calculate the back-EMF and torque produced by these machines. Another problem experienced with the FEM software was to obtain accurate torque results. Excessive ripple torque oscillations were sometimes experienced which took a considerable amount of time to minimise with constant refinement to the meshing of the machine parts. Reduction in the mesh element size unfortunately also added to the simulation time. The requirement for an accurate analytical model of the RFAPM machine was also necessary in order to reduce the amount of time spent on successive FEM simulation to obtain the optimum pole arc width of the permanent magnet in order to minimise the harmonic content of the radial flux-density distribution in the the stator windings. In this dissertation, the use of single-layer and double-layer, non-overlapping, concentrated winding for the RFAPM machine is also investigated. It was decided to include a comparison of these two non-overlapping winding configurations with a “hypothetical” concentrated, overlapping winding configuration. This would allow us to gauge the effectiveness of using nonoverlapping winding with respect to the reduction in copper losses as well as in the reduction in copper volume. It would also allow us to investigate the extent of how much the developed torque is affected by using non-overlapping windings instead of overlapping windings.
AFRIKAANSE OPSOMMING: In hierdie proefskrif word ’n nuwe tipe elektriese masjien, ’n Radiale-vloed Lugkern Permanent Magneet Masjien met ’n dubbelkantige rotor en nie-oorvleuelende Windings voorgestel. Die konsep vir die Radiale-vloed Lugkern Permanent Magneet Masjien, of RVLPM vir kort, is afgelei vanaf die Dubbelkantige Rotor, Aksiale-vloed Lugkern (AVLPM) masjien. Een van die probleme wat met AVLPM masjiene ondervind word, is die defleksie van die rotorjukke as gevolg van die sterk aantrekkingskragte van die permanente magnete, veral in dubbelkantige rotor masjiene. Die hoof voordeel wat die RVLPM masjien inhou bo die AVLPM masjien, is die feit dat die RVLPM se rotorjukke silindries is in plaas van ronde skywe. As gevolg van die strukturele integriteit van ’n silinders, speel die aantrekkingskrag van die permanente magnete nie meer ’n rol nie. Die fokus van die proefskrif gaan oor die deeglike analitiese analise van die dubbelkantige RVLPM masjien. Weens die feit dat die RVLPM masjien ’n lugkern masjien is, is daar besluit om ondersoek in te stel na die moontlikheid om ’n lineêre, analitiese model vir die masjien op te stel waarmee die radiale-vloeddigtheid, teen-EMK asook die ontwikkelde draaimoment vir die masjien akkuraat bereken kan word. Die behoefde aan ’n akkurate analitiese model vir die dubbelkantige rotor RVLPM masjien is om die blinde vertroue te elimineer wat daar in Eindige-Element Modellering (EEM) sagteware gestel word om die teen-EMK en ontwikkelde draaimoment van die RVLPM masjien uit te werk. ’n Verdere probleem wat daar met EEM sagteware ondervind is, is die akkurate berekening van die ontwikkelde draaimoment. Oormatige rimpel draaimoment ossillasies is soms ondervind wat heelwat tyd geverg het om te minimeer, deur voortdurende verfyning van die EEM maas in die verskillende dele van die masjien. Soos die maas egter kleiner word, verleng dit die simulasie tyd van die EEM aansienlik. Nog ’n rede vir ’n akkurate analitiese model van die RVLPM masjien, is om vinnige metode te verkry om die optimale permanente magneet pool hoekwydte te verkry, wat die minste Totale Harmoniese Vervorming (THV) in die radiale-vloeddigtheidsdistribusie in die statorgebied sal veroorsaak, sonder om herhaaldelike EEM simulasies te loop. In die proefskrif word die gebruik van enkellaag en dubbellaag, nie- oorvleuelende, gekonsentreerde wikkelings vir die RVLPM masjien ook ondersoek. Daar is besluit om hierdie twee nie-oorvleuelende windingskonfigurasies met ’n “hipotetiese” gekonsentreerde, oorvleuelende windingskonfigurasie te vergelyk. Dit behoort ons in staat te stel om die doeltreffendheid van nie-oorvleuelende windings te bepaal, met betrekking tot die afname in koperverliese asook die afname in kopervolume. Verder sal dit ons in staat stel om ook mate waartoe die ontwikkelde draaimoment deur nie-oorvleuelende windings beïnvloed word, te ondersoek.

Cette thèse présente le dimensionnement d’une machine électrique à rotor disque pour la traction de véhicules hybrides. Un état de l’art complet sur les machines électriques à rotor disque permet de montrer que la machine à flux axial à rotor central est la plus adaptée. Différentes géométries du circuit magnétique sont successivement étudiées et comparées par simulations par éléments finis. Pour maximiser le rendement de la machine, les pertes d’origine électromagnétique sont étudiées. Un modèle analytique des pertes par effet de peau dans les conducteurs de cuivre est proposé et validé par éléments finis. Un second modèle analytique estime les pertes par courant induits dans les aimants permanents pour tous les points de travail de la machine se basant sur uniquement trois simulations par éléments finis permettant ainsi un gain de temps important lors du dimensionnement. Deux méthodes de dimensionnement sont comparées : le dimensionnement manuel par essais/erreurs et l’optimisation multi-objectifs. Cette dernière méthode automatise le dimensionnement et permet une optimisation plus pointue et une forte amélioration des performances. Dans ce cas, la densité de couple a par exemple été augmentée de 29%. La machine à flux axial dimensionnée est comparée avec une machine à flux radial pour véhicules hybrides. Cette comparaison révèle le potentiel de la machine à flux axial avec notamment une densité de couple augmentée de plus de 20%. Enfin, deux prototypes ont été construits et mesurés pour valider les simulations
This PhD presents the design of a disc rotor electric machine for the traction of hybrid vehicles. A complete state of the art enables the selection of the internal rotor axial flux machine which is the most suited to this application. Different geometries of the magnetic circuit are successively studied and compared with finite elements simulations. To maximize the efficiency of the machine losses generated in the magnetic circuit are studied. An analytic model on the skin effect in the copper conductors is proposed and validated with finite elements simulations. A second analytic model estimates the eddy current losses in the permanent magnets for every operating point of the machine based on only three finite element simulations enabling an important time-saving. Two dimensioning methods are compared: the manual dimensioning based on a tries/errors method and the multi-objectives optimization. This last method automates the dimensioning and enables a more refined optimization and a strong improvement of the performances. For example, the torque density has been improved by 29% in that case. The designed axial flux machine is compared to a state of the art radial flux machine for hybrid vehicle. This comparison shows the potential of the axial flux machine with an improvement of the torque density by more than 20%. Finally two prototypes have been built and measured to validate the simulations

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
As máquinas síncronas de ímãs permanentes têm a vantagem de não consumir energia para a criação do campo magnético no rotor. O propósito específico desta Tese é o projeto, a construção e a avaliação de uma máquina com grande número de polos, de enrolamentos concentrados, com ímãs permanentes inseridos no interior do rotor, com duas formas geométricas diferentes: um com ímãs alinhados e a outra com ímãs inclinados axialmente. As justificativas para este estudo foram a possibilidade de eliminação de multiplicadores mecânicos de velocidade e sistemas auxiliares de excitação em centrais geradoras de energia. O projeto usou um motor de indução trifásico com rotor gaiola de esquilo de 250W de 12 polos. Partindo dos próprios dados construtivos do estator, calculou-se a densidade de fluxo magnético, especificando os ímãs permanentes de neodímio. No desenvolvimento foi construído um novo rotor modular e simples. Posteriormente, a máquina foi avaliada em laboratório com o objetivo de verificar a quantidade e a qualidade da energia com a máquina atuando como gerador. Por último, os resultados encontrados na avaliação da máquina funcionando como gerador com ímãs alinhados revelaram distorção harmônica total (DHT) 16%, capacidade de geração 475W a 221V – 60Hz e como aspecto desfavorável o alto torque de travamento. Com ímãs inclinados, DHT de 7 a 8%, capacidade de geração de 236W a 195V – 60Hz e baixo torque de travamento. Este trabalho mostra que os ímãs inclinados modularmente são uma opção de máquinas elétricas com satisfatório desempenho da máquina como gerador de energia com razoável qualidade no contexto de geração distribuída de pequena potência. Além das condições técnicas têm-se o baixo custo e a manutenção reduzida do gerador com ímãs inclinados em relação aos geradores síncronos convencionais
Synchronous machines of permanent magnets present the advantage of no power consumption for the creation of the magnetic field in the rotor. The specific purpose of this thesis is the project, its construction and the evaluation of a multi-pole of concentrated coils with permanent magnets inserted in the rotor by two different geometrical forms: aligned and skewed magnets. The vindications for this study were the possibility of eliminating both the mechanical speed reducers and the excitation energy systems in electrical powerplants. The project used a three-phase induction motor (squirrel cage rotor type) of 250W and 12 poles. Starting from the original stator constructive data, we proceeded the calculi of the magnetic flux density to determine the remanent flux of the neodymium permanent magnets. In the development of the work, a new simple and modular rotor was constructed. Subsequently, the machine was evaluated in a laboratory with the purpose of checking the quantity and quality of energy produced operating as a generator. The results obtained in the evaluation of the motor operating as a generator equipped with aligned magnets were 16% of total harmonic distortion (THD), with a generating capacity of 475W at 221V – 60 Hz, though with an adverse aspect of needing a high inertial torque (cogging torque). The machine working with skewed magnets produced 7 and 8% of total harmonic distortion (THD), with a generating capacity of 236W at 195V – 60 Hz and a low cogging torque. This work demonstrated that the modular skewed magnet is an option of electrical machines presenting satisfactory performance as a generator with a reasonable quality in the context of small distributed power generation. Besides the technical conditions, it should also be considered the low cost and reduced maintenance of skewed magnets in relation to the conventional synchronous generators

Resumo: As máquinas síncronas de ímãs permanentes têm a vantagem de não consumir energia para a criação do campo magnético no rotor. O propósito específico desta Tese é o projeto, a construção e a avaliação de uma máquina com grande número de polos, de enrolamentos concentrados, com ímãs permanentes inseridos no interior do rotor, com duas formas geométricas diferentes: um com ímãs alinhados e a outra com ímãs inclinados axialmente. As justificativas para este estudo foram a possibilidade de eliminação de multiplicadores mecânicos de velocidade e sistemas auxiliares de excitação em centrais geradoras de energia. O projeto usou um motor de indução trifásico com rotor gaiola de esquilo de 250W de 12 polos. Partindo dos próprios dados construtivos do estator, calculou-se a densidade de fluxo magnético, especificando os ímãs permanentes de neodímio. No desenvolvimento foi construído um novo rotor modular e simples. Posteriormente, a máquina foi avaliada em laboratório com o objetivo de verificar a quantidade e a qualidade da energia com a máquina atuando como gerador. Por último, os resultados encontrados na avaliação da máquina funcionando como gerador com ímãs alinhados revelaram distorção harmônica total (DHT) 16%, capacidade de geração 475W a 221V - 60Hz e como aspecto desfavorável o alto torque de travamento. Com ímãs inclinados, DHT de 7 a 8%, capacidade de geração de 236W a 195V - 60Hz e baixo torque de travamento. Este trabalho mostra que os ímãs inclinados modularmente são uma opção de máquinas elétricas com satisfatório desempenho da máquina como gerador de energia com razoável qualidade no contexto de geração distribuída de pequena potência. Além das condições técnicas têm-se o baixo custo e a manutenção reduzida do gerador com ímãs inclinados em relação aos geradores síncronos convencionais
Abstract: Synchronous machines of permanent magnets present the advantage of no power consumption for the creation of the magnetic field in the rotor. The specific purpose of this thesis is the project, its construction and the evaluation of a multi-pole of concentrated coils with permanent magnets inserted in the rotor by two different geometrical forms: aligned and skewed magnets. The vindications for this study were the possibility of eliminating both the mechanical speed reducers and the excitation energy systems in electrical powerplants. The project used a three-phase induction motor (squirrel cage rotor type) of 250W and 12 poles. Starting from the original stator constructive data, we proceeded the calculi of the magnetic flux density to determine the remanent flux of the neodymium permanent magnets. In the development of the work, a new simple and modular rotor was constructed. Subsequently, the machine was evaluated in a laboratory with the purpose of checking the quantity and quality of energy produced operating as a generator. The results obtained in the evaluation of the motor operating as a generator equipped with aligned magnets were 16% of total harmonic distortion (THD), with a generating capacity of 475W at 221V - 60 Hz, though with an adverse aspect of needing a high inertial torque (cogging torque). The machine working with skewed magnets produced 7 and 8% of total harmonic distortion (THD), with a generating capacity of 236W at 195V - 60 Hz and a low cogging torque. This work demonstrated that the modular skewed magnet is an option of electrical machines presenting satisfactory performance as a generator with a reasonable quality in the context of small distributed power generation. Besides the technical conditions, it should also be considered the low cost and reduced maintenance of skewed magnets in relation to the conventional synchronous generators
Orientador: Teófilo Miguel de Souza
Coorientador: Inácio Bianchi
Banca: Rubens Alves Dias
Banca: Jose Feliciano Adami
Banca: Osiris Canciglieri Junior
Banca: Marcio Zamboti Fortes
Doutor

Les travaux de cette thèse s’inscrivent dans le contexte du développement de groupes motopropulseurs électriques pour véhicules automobiles. Ces développements ont mis en lumière les problématiques liées aux phénomènes acoustiques et vibratoires des machines électriques, spécifiques à l'application automobile. L'objectif de ces travaux est la mise en place de lois de commande dédiées à la réduction d'harmoniques de courant à l'origine d'harmoniques vibratoires.Pour cela, les différents éléments du système ont été modélisés, puis les paramètres du modèle électrique de la machine ont été identifiés au moyen de mesures expérimentales.Deux stratégies de commande ont ensuite été développées puis mises en place. D'une part, un régulateur dédié à l'harmonique de courant visé a été synthétisé par optimisation H-infini. D'autre part, la modélisation de l'origine de cet harmonique comme provenant d'un signal perturbateur externe a permis la compensation de celui-ci au moyen d'un observateur.L'efficacité de ces deux stratégies sur la réduction des harmoniques de courant visés et des harmoniques vibratoires correspondants a été validée expérimentalement sur banc d'essai vibratoire
This work takes place in the context of the development of powertrains for electric vehicles. Those developments have raised new issues such as noise and vibrations of electrical machines, which are important issues in automotive applications. The aim of this thesis is to develop control laws dedicated to the reduction of currents harmonics that are responsible for vibration harmonics.In that purpose, different parts of the system have been modelled. Parameters of the electrical model of the studied machine have then been identified thanks to experimental measurements.Two different control laws are proposed and developed. One the one hand, a controller is synthetized thanks to H-infinity optimization. On the other hand, the studied current harmonic is modelled as coming from an external disturbance. This virtual disturbance is estimated thanks to an observer and compensated

This thesis deals with the problem of the high-speed electrical machines. In the introduction summary of the high-speed machines are discussed. Induction machine with squirrel cage winding and solid rotor is chosen as suitable solution for given requirements. The multiple types of designs of the induction machines with solid rotor and problematic areas are discussed. Main part of this thesis is an electromagnetic design of the machine with respect to mechanical stress. The designed machine is analyzed with the use of finite element method in ANSYS Mechanical and Maxwell software.

O presente trabalho apresenta uma transformação dq não senoidal e sua aplicação em máquinas síncronas com ímã permanente na superfície do rotor (MSIP) e forma de onda de FEM não senoidal. O modelo resultante da aplicação dessa transformação permite o controle direto do torque eletromagnético, permitindo reduzir as ondulações do torque produzido nesse tipo de máquina. A redução dessas ondulações em MSIPs não senoidais possibilita que esse tipo de máquina seja empregado em aplicações onde somente MSIPs senoidais, que possuem custo mais elevado, poderiam ser usadas. Simulações e resultados práticos, obtidos pela implementação do sistema de controle vetorial não senoidal desenvolvido, são apresentados no trabalho. Pelos resultados obtidos, pode-se verificar que o método proposto é eficaz na redução das ondulações do torque eletromagnético em MSIPs não senoidais.
This work presents a non-sinusoidal dq transformation and its application in permanent- magnet synchronous machines (PMSM) with a non-sinusoidal back-EMF waveform. The resulting model of the application of such transformation permits direct control of machine electromagnetic torque, which achieves the reduction of torque ripple. The reduction of torque ripple in non-sinusoidal PMSMs makes possible the use of this kind of PMSM instead of sinusoidal PMSMs, which are more expensive. Simulation and practical results, obtained by the implementation of such non-sinusoidal vectorial control system, are shown in this work. Those results show that the method presented is efficacious in the torque ripple reduction in non-sinusoidal PM synchronous machines.

Neste trabalho é estudado um motor trifásico de ímã permanente no rotor, com fluxo não senoidal, através da análise do campo magnético. Essa máquina foi projetada utilizando-se a estrutura ferromagnética do estator de um motor de indução monofásico de 24 ranhuras o qual recebeu um novo enrolamento trifásico, e foi construído o rotor que é constituído de ímãs permanentes em sua superfície. Ela é aplicada em compressores herméticos de refrigeração, possibilitando o controle de velocidade e a melhoria da eficiência, quando comparada às demais máquinas utilizadas para a mesma aplicação. O estudo é realizado através da análise dos resultados obtidos utilizando-se um programa computacional baseado no método dos elementos finitos, aplicado em grandezas como: tensão induzida, densidade de fluxo magnético, torque eletromagnético e perdas. São apresentados resultados numéricos comparativos para a máquina existente (protótipo) com as seguintes alterações: diminuição do tamanho do entreferro, troca dos ímãs de ferrita pelos de NdFeB (Bonded) e, juntamente com essas mudanças, o recálculo do número de espiras e do diâmetro do enrolamento do estator.
In this work is studied a three-phase permanent-magnet motor, with nonsinusoidal flux, through the analysis of magnetic field. This machine was designed to use the same stator of a 24 slots single-phase induction motor that received a new three-phase winding. The rotor consists of permanent-magnet on its surface. The main application of this machine is in hermetic compressor household refrigeration systems. It has speed control and better efficiency than other machines used for the same application. The study is made through the analysis of numerical results, obtained by a software joint in the finite element method. The results consist in electromagnetic quantity like, back-emf, magnetic flux density, electromagnetic torque and losses. Comparisons between the prototype with these changes are presented: fall in the size of airgap, exchange of ferrite magnets for NdFeB (Bonded) magnets and, together with these changes, the number of turns in each winding and the wire diameter are recalculated.

Les véhicules électriques (VE) ou les véhicules électriques hybrides (VEH) offrent de nombreux avantages par rapport aux véhicules à moteur à combustion interne classiques. Selon les tendances récentes, la demande en VE(H) efficaces devrait augmenter considérablement. Pour une gamme haute puissance, la technologie des moteurs à aimants permanents a été le choix privilégié dans les véhicules électriques hybrides. La demande croissante de moteurs à haut rendement est en corrélation directe avec la demande d'aimants puissants (NdFeB ou SmCo) utilisant des terres rares. La disponibilité et la production des terres rares sont très critiques particulièrement pour les terres rares lourdes. L'objectif de cette thèse de doctorat est donc de concevoir un moteur Halbach à rotor extérieur pour une application VE(H) avec recyclage et réutilisation faciles des aimants. En outre, le projet vise à étudier et à proposer la fabrication d'un aimant Halbach utilisé dans les moteurs de forte puissance pour application VE.Tout d'abord, la fabrication d'un aimant Halbach utilisant un aimant NdFeB fritté avec et sans liant a été étudiée. L'étude montre que la fabrication d'une configuration de Halbach à l'aide d'un aimant collé est beaucoup plus facile et plus rentable que la fabrication d'un aimant fritté. La caractérisation d'un aimant NdFeB lié utilisé pour fabriquer un aimant Halbach a également été réalisée. Diverses voies de recyclage des aimants frittés et liés ont été analysées; on peut en déduire que les aimants collés sont beaucoup plus faciles à recycler, de manière rentable et respectueuse de l'environnement. La thèse propose également un moyen de recyclage pour l'aimant collé utilisé dans le moteur.Deuxièmement, un moteur à aimant Halbach collé a été conçu en modélisation éléments finis 2D et 3D. Pour obtenir un moteur très efficace et compact, on a utilisé un bobinage à pas fractionnaire. Les propriétés de l'aimant Halbach ont été calculées à l'aide du modèle éléments finis et comparées au modèle analytique. Les résultats obtenus par les deux approches étaient similaires. De plus, l'impact des combinaisons nombre d’encoches-pôles sur les pertes moteur et le couple a été étudié, en particulier les pertes Joule (compte tenu de toutes les contraintes de conception). Différentes stratégies pour utiliser des aimants recyclés à faible rémanence sont également présentées. L'utilisation d'un aimant recyclé avec une augmentation de la longueur axiale du moteur pourrait être le meilleur choix compte tenu de différents facteurs, notamment la fabrication de l'aimant Halbach. Sur la base de différentes études paramétriques, une conception du moteur a été proposée et un prototype a été construit. Il a été montré qu'un aimant Halbach de grande puissance pouvait être construit de manière économique avec un aimant NdFeB collé. La densité de flux d'entrefer du rotor, mesurée sur le prototype, est en étroite concordance avec les valeurs calculées.De plus, la méthodologie WIRE (Weighted Index of Recycling and Energy) a été présentée pour comparer différentes conceptions de moteurs en fonction de leur performance et de leur recyclabilité. La méthode développée produit deux indices basés sur-Facilité de recyclage du moteur en ce qui concerne le matériau, le montage et le démontage des aimants.-Impact d'un aimant recyclé sur la consommation d'énergie d'un moteur pendant sa durée de vie.En utilisant ces deux indices, on peut facilement analyser les avantages et les inconvénients des différentes conceptions sur la base de la recyclabilité et de l'efficacité énergétique. La conception proposée a été évaluée à l'aide cette méthode et on montre que le moteur est facile à monter et à démonter. De plus, l’assemblage moteur (sans colle) permet une extraction facile des aimants et une réutilisation directe. L'indice énergétique évalué du moteur montre l'impact de l'utilisation d'un aimant recyclé et sa viabilité pour les applications VE dans différents scénarios
Electric vehicles (EVs) or Hybrid electric vehicles (HEVs) offer many advantages over the conventional IC engine vehicles. According to recent trends, the demand for efficient (H)EVs is expected to grow significantly. For a high-power range, permanent magnet based motor technology has been the preferred choice for motors deployed in (H)EVs. Growing demand of highly efficient motors is in direct correlation to the demand of strong magnets (NdFeB or SmCo), which uses rare earth elements (REE). The availability and supply of REEs specially heavy REEs is very critical. Therefore, the aim of this doctoral thesis is to design an outer rotor Halbach motor for a (H)EV application with easy recycling and reuse of the magnet. Further, the project aims to investigate and propose the manufacturing of a Halbach magnet used in a high power motor EV applications.Firstly, the manufacturing of Halbach magnet using a sintered and a bonded NdFeB magnet was investigated. The study shows that the manufacturing of Halbach array using a bonded magnet is much easier and more cost effective than the sintered magnet. The characterisation of a bonded NdFeB magnet used for manufacturing a Halbach magnet was also performed. Various recycling routes for both sintered and bonded magnets were analysed and it can be inferred that bonded magnets are much easier to recycle in a cost effective and environment friendly manner. The thesis also proposes the recycling route for the bonded magnet used in the motor.Secondly, a motor with bonded Halbach magnet was designed using 2D and 3D FEM. To achieve a highly efficient and compact motor, fractional slot tooth coil winding was used. The properties of Halbach magnet was calculated using FEM model and benchmarked against the analytical model. The results obtained from the two approaches were in close agreement. Further, the impact of slot pole combinations on motor losses and the subsequent torque were investigated, specifically eddy loss (considering all the design constraints). Different strategies to use recycled magnet with lower remanence is also presented. It is shown that using a recycled magnet with increased axial length of the motor could be the best choice considering different factors, specially manufacturing of the Halbach magnet. Based on different parametric studies a design of the motor was proposed and prototype was built. It was demonstrated that a high power Halbach magnet could be built economically using a bonded NdFeB magnet. The airgap flux density of the rotor, measured on the prototype is in close agreement with the calculated values.Additionally, WIRE (Weighted Index of Recycling and Energy) methodology was presented to benchmark different motor designs on the basis of performance and recy- clability. The method developed produces two indices based on:• Ease of motor recyclability considering material, assembly and disassembly of magnets.• Impact of a recycled magnet on the energy consumption of a motor during its operational lifetime.Using both the above indices, one can easily analyse the pros and cons of different motor designs on the basis of recyclability and energy efficiency. The proposed motor design was evaluated using the developed method and it is shown that the motor is easy to assemble and disassemble. In addition, the motor assembly (glue free) enables easy magnet extraction and direct reuse. The evaluated energy index of the motor shows the impact of using a recycled magnet and its viability for EV applications in different scenarios

Este trabalho tem como objetivo o projeto, construção e análise do funcionamento de uma máquina elétrica síncrona trifásica com núcleo do rotor produzido a partir da metalurgia do pó e ímãs de neodímio-ferro-boro para aplicação em aerogeradores. Tomando como base a máquina elétrica modelo VTOP da fabricante Grupo Voges, foram realizadas mudanças na forma construtiva dos núcleos do estator e do rotor. O pacote chapas que compõem o núcleo do estator foi montado de maneira que as ranhuras apresentem um ângulo de inclinação de 10º ao longo de toda a extensão da máquina. Para o rotor, foi projetado e construído um núcleo através do processo de metalurgia do pó utilizando como matéria-prima pó de ferro puro. A esse novo núcleo foram acrescentados ímãs de neodímio-ferro-boro. Após a montagem dos componentes, a máquina elétrica foi ensaiada em uma bancada de testes. Paralelamente com a confecção do núcleo foi efetuada a simulação computacional da máquina com três tipos diferentes materiais no núcleo do rotor. Os resultados encontrados indicaram que a metalurgia do pó é uma alternativa viável para produção do núcleo de máquinas elétricas. Entretanto alterações na topologia e na forma de fixação dos ímãs são necessárias para um melhor desempenho.
This work aims at the design, construction and performance analysis of a three-phase synchronous electric machine with a rotor core produced by powder metallurgy and neodymium-iron-boron magnets for application in wind turbines. Based on the electric machine VTOP model of the manufacturer Grupo Voges, changes were carried out in the constructive form of the stator and rotor cores. The bundle of plates that make the role of stator core were mounted with a 10º slope along the entire length of the machine. For the rotor, a core was designed and built by employing powder metallurgy process using pure iron powder as raw material. The neodymium-iron-boron magnets were added to this new core. After assembling the components, the electric machine was tested on a test bench. Simultaneously with the core fabrication, the machine was simulated with three different materials in the rotor core. The results indicated that powder metallurgy is a viable alternative to produce the core of electric machines. However, changes in the topology and shape of the magnets are necessary for better assembly, improving the performance.

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.

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.

This diploma thesis deals with a creation of a “Classification Document” of asynchronous motors with a short-circuit armature with axial heights of 355, 400, 450, 500, and 560 mm. Furthermore, it is concerned with a creation of an integral design documentation for the production and assembly of these motors at the company TES VSETÍN, s.r.o. By writing this diploma thesis I would like to achieve a simplification of communication with the customers during the processing of asynchronous motors orders and to speed up the processing of asynchronous motors orders not only in the design department but also the complete technologic preparation of the production which will surely be provided by this integrated documentation.

This work deal with troubleshooting of problem parts of high-speed induction machines. Introduction is about conception of induction machines with reference to construction specialities due to high rpm and because machines are fed by inverter. Next part is focused to design problems. A classical induction machine was measured to determination change of various losses in classic and high-speed induction machines. The computation of laboratory sample high-speed motor was specified for calculation of effective resistance and leakage reactance of solid-steel rotor with copper layer. The results of numerical calculation were validated by using finite elements method and machine design was adjusted for improving operation characteristic.

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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