With their various structures and operations, the operational magnetic flux densities inside those energy conversion mechanisms are non-uniformly distributed, hence large deviations are exhibited among the actual and the estimated values of iron losses in those electric machines. The available datasheets provided by the steel manufacturers derived from standard measurement systems can only cover some typical information, accuracies of applying these data for related machine performance evaluations at those operational conditions are always uncertain. To establish more convincing datasheet for the calculation of iron loss in machines, standing between the steel manufacturers and the electric machine designers, the application of improved magnetic circuits analysis and the numerical Epstein Frame is proposed. The static transformers and the rotary synchronous switched-reluctance motors will be thoroughly calculated for illustrations. Based on the aforementioned datasheets and the iron losses evaluation procedure, when designing the similar machines, the iron losses could be appropriately estimated, and more detailed information could be supplied.

Work had been established for traction machine design aspects in this research. The effect of multiphase design for Permanent Magnet (PM) machine was investigated. The electromagnetic characteristics of both 3-phase and 9-phase machine, along with different magnet designs, were simulated and analyzed by using the program developed during the process. The software used were FEMM and MATLAB. The iron loss for different designs was established, based on the analytical flux density obtained by 2-D stepping FEA method. The harmonic of flux waveform and rotating field were also considered for difference areas in the machine models. The prediction was compared with experimental data collected in open circuit. The simulation result shown that there was a minimum 4% torque gain and noticeable less torque ripples for 9-phase machine, comparing with 3-phase one, with the same excitation phase current. The embedded magnet rotor design was suggested to monitor the demagnetization of each magnet closely, since some area of the magnet could be demagnetized even when the working point of magnet was well distance away from the nonlinear region of its characteristic. There were about 6% less iron loss was produced in 9-phase model than 3-phase model. The implemented method for calculating iron loss was more accurate within 3500 rpm rotor speed comparing with other approaches.

The objective of this thesis is to provide a quick process to estimate iron losses of the electric machines with various structures that employ electromagnetic steels in their designs. Due to non-uniform distributed operational magnetic flux densities resulted from the machine structures, the iron losses of machines can not be properly estimated. The aim of the scheme is to modify the deviations among the measurements and the calculations. At first, several standardized steel modules that can be used to assemble the machine structures are established, then a test-bed with closed magnetic path to supply operational magnetic field inside those electric machines is constructed. To calculate the iron loss of each module, the averaged flux densities for each area of the module are measured by needle probe method, and the corresponding magnetic field intensities are calculated from Jiles and Atherton (J-A) model hysteresis model. Finally, the iron loss datasheets for each module are constructed by these measurements, and the iron losses of machines are estimated through assembling the modules. In this thesis, a switched-reluctance machine (SRM) is selected for assessment comparisons, and its iron loss can be calculated through datasheets according to the machine structure. It is believed that the findings of this study can provide a valuable reference and a reliable process in motor designing and manufacturing.

The aim of this thesis is to design a kilowatt three-phase step-down rotary transformer for a permanent magnet DC motor. The permanent magnet DC motor has an on-rotor drive system, and therefore requiring a power supply that can transfer power to its drive unit without mechanical contact. The rotary transformer has a detached magnetic coupling structure that qualifies it as a potential method for the wireless power transfer. This thesis studies the rotary transformer as a static device, focusing on its core loss. By using a transient finite element analysis of COMSOL Multiphysics and an iron loss prediction model, the rotary transformer was optimized in terms of efficiency and power density for the on-rotor drive system through proper material selection and geometry exploration. After this, a mechanical design, which based on a literature review of the influences of manufacturing processes on electrical steels, was proposed for realizing the core fabrication and the rotary transformer assembly. The results show that the rotary transformer can step down 400 V/50 Hz three-phase voltage to 13.15V in a Delta-wye connection and output 1.17kW power over an air-gap of 0.3mm with 95.94% overall efficiency. The proposed mechanical design enables the transformer to minimize the core loss and the manufacturing cost. Without using resonant inductive coupling, this transformer design simplifies the power supply for the motor, thereby decreasing the motor manufacturing and maintenance cost.

The objective of this thesis is to provide a reliable and effective iron loss estimation scheme for the electromagnetic steel products in the design and on-line operation stages. To investigate the possible performance of electromagnetic steel products, proper iron loss information of the products that are constructed by different steels is one of the key concerns. Along with the various power electronic device applications and iron core structures, the magnetic fluxes flowing through the machine cores will be non-uniform and include harmonic terms. Unless excessive computation efforts in expensive software tools are performed, large discrepancies will be exhibited the estimated and actual values of machine iron losses. To overcome these drawbacks, a rational machine iron loss estimation scheme is proposed. By adopting the iterative magnetic equivalent circuits and the nonlinear magnetic characteristics of the electromagnetic steels, the preliminary operational flux information in the machine is first obtained, and then a numerical Epstein Frame test circuit with magnetizing inductance modeled by Preisach model is applied. With appropriate circuit input voltages devised from preliminary information, the detailed hysteresis inner-loop characteristics resulting from product structures and magnetization harmonics can be properly modeled. Based on the circuit results, the iron losses of electric machines with any operation can be rationally evaluated, and a valuable reference in machine designing can be provided.

We will present the approaches used to investigating the power loss for the stranded core transformers. One advantage of using stranded core is to reduce power loss or enhance transformer efficiency. One difficulty in the modeling of this type of transformer is that the core is not solid (there are small gaps between core wires due to circular cross section). A two dimensional finite element method with nodal basis function for magnetostatic field was developed to study the effects of the small gaps between core wires. The magnetic flux densities are compared for the uniform (solid) cores and the stranded cores for various permeability values. The effects of different air gap dimensions in stranded core to the magnitude of magnetic flux density were also discussed. The results of the two dimensional study were applied to modify the B-H curves in a 3D simulation with an equivalent simplified uniformed core transformer model via Ansoft Maxwell 3D. This is achieved by output the magnitude of magnetic flux density at fixed points of mesh center. The total core loss of a transformer was predicted by integration of the losses of all elements.

Most electrical machines available in the market utilise some form of silicon iron (SI) as the core material. Although SI based electrical machine manufacturing methods are well established and simple, SI has significant iron losses specifically in high frequency variable-speed motor drive applications. Two alternative magnetic materials have recently been developed: amorphous magnetic material (AMM) and soft magnetic composite, which can each offer unique characteristics that can be utilised to improve the performance of electric machines. AMM offers extremely low iron losses which makes it a good candidate for high-efficiency and variable-speed motor applications. However, due to handling and cutting limitations, AMM has not been utilised widely in rotating electrical machines. A commercially viable AMM cutting technique was recently developed by the industrial partner of this project. It is thus now practical to cut the AMM ribbon into a machine stator, particularly for axial-field stators which generally require less cutting than radial-field stators. This thesis investigates an innovative motor design based on applying the cut AMM in an axial-field permanent magnet (AFPM) machine for general drive applications. It includes a detailed review of the analytical approach, finite element analysis (FEA), iron loss investigation and prototype performance comparisons. Analytical analysis of the AFPM machine was performed and the key design variables were evaluated to optimise the design parameters based on the use of AMM. The AMM cutting constraints, design and performances trade-offs were also investigated in the design. The research study provides a design procedure to determine the basic physical size and configuration (e.g. combination of the number of slots and poles, slot width and depth, number of winding layers, air gap length, magnet thickness) based on certain basic specifications. In addition, a comprehensive investigation was conducted on the iron loss of various materials to compare these with AMM. Due to the three dimensional (3D) nature of the AFPM structure, the theoretical design was validated using 3D FEA and extensive simulation results are provided. A number of AMM AFPM prototypes were successfully designed and constructed. Due to limited available materials, the prototypes were built using uncoatedAMMribbon which has substantially higher iron loss characteristics. Nevertheless, it is believed that it would still provide a valuable understanding of the real machine characteristics and allow initial design validation. The prototype was tested in a custom-built test rig to validate the analytical and 3D FEA predictions. Overall, a good correspondence between the results and predictions has been achieved. Extensive experiments have been conducted to investigate and demonstrate the characteristics of the AMM prototype machines which are based on fractional-slot concentratedwinding single-sided AFPM machines. This includes comparisons against identical silicon iron and soft magnetic composite prototypes. In addition, the laboratory experimental results also highlighted the significant effect of the open-circuit losses on the overall machine performance. Therefore, the open-circuit loss components which includes bearing, windage, magnet and iron losses were separated based on 3D FEA and experimental results. The above research studies demonstrated the potential and feasibility of cut AMM to produce highly efficient AFPM machines. In addition, the innovative cutting technique also has the potential for mass production of low-cost AMM machines. The research work in this thesis makes a significant contribution to the design of axial-field permanent magnet machines based on AMM. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1375647 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2009

Le travail proposé est le résultat d’une collaboration entre le Laboratoire Laplace et l’IRT SaintExupéry. Il s’inscrit dans un projet visant à améliorer l’intégration des systèmes électriques afin d’électrifier les aéronefs. Le développement de l’énergie électrique à bord des aéronefs a de nombreux avantages : gain de masse, optimisation facilitée, … Plus précisément, c’est l’utilisation des machines électriques qui est ici étudiée. Actionneur, compresseur, beaucoup de système utilisant des énergies non-électriques peuvent être remplacés par des machines électriques. Comme dans tout système de conversion d’énergie, des pertes sont présentes et ce sont les pertes magnétiques, appelées perte fer, qui sont au cœur de cette thèse. Le réseau électrique avion, ainsi que les dispositifs de commande de ces machines, induisent une large augmentation de la proportion des pertes fer par rapport aux autres pertes. Les rendements diminuent et c’est surtout leur prédiction qui pose problème : les machines électriques sont surdimensionnées par sécurité, elles deviennent moins efficaces et le gain en masse est réduit. C’est pourquoi il est indispensable d’une part de comprendre le comportement des matériaux magnétiques utilisés dans les machines électriques dans des conditions non-idéales : il s’agit de la caractérisation des matériaux magnétiques. D’autre part, il est nécessaire d’améliorer les modèles de pertes fer afin de rendre leur prédiction efficace et optimiser le dimensionnement des machines électriques. Plus leur prédiction sera précise, plus les facteurs d’influence sur les pertes seront déterminés. Il sera alors possible d’envisager une optimisation plus globale de la chaîne électromécanique. Cette thèse est une première étape vers cette intégration globale. La caractérisation des matériaux fut faite sous diverses conditions. Tout d’abord, des champs magnétiques B unidimensionnels ont été étudiés. L’influence de leur spectre sur les pertes fer était au cœur de cette caractérisation : influence de l’amplitude ou de la fréquence dans le cas de champs sinusoïdaux, puis de la fréquence et de la phase d’harmoniques dans le cas de spectre plus complexes. Les pertes fer sont très sensibles à ces paramètres, ils sont donc à prendre en compte dans le dimensionnement des machines électriques. La modélisation des pertes proposée ensuite passe par une reconstitution du cycle d’hystérésis. Il s’agit donc de prédire le champ B à partir du champ H. Basée sur le modèle Play, la modélisation quasi-statique scalaire développée a montré sa précision et sa prédictibilité. Cependant, étant scalaire et quasi-statique, ce modèle ne fonctionne pas en fréquence. Un modèle analytique de courants de Foucault ainsi que des propositions de dynamisation ont été développés. Le modèle de courants de Foucault permettrait de tenir compte des effets de fréquence et donc de compléter le modèle quasi-statique. / The work proposed here took place in IRT Saint-Exupéry in collaboration with Laplace Laboratory. It is part of a project aiming for the integration of electrical systems improvement in order to electrify aircraft. The development of electrical energy aboard aircraft has many advantages: mass gain, optimization facilitated... More precisely, the using of electrical machines is studied here. Actuator, compressor, a lot of system using non-electric energies can be changed for electrical machines. As in any energy conversion system, losses cannot be avoided and especially iron losses, which are the main topic of this thesis. The airplane electrical networks, as well as electrical machine control devices, induce a large increase in iron loss proportion compared to other losses. Yields are diminishing but iron loss prediction is the main issue: electrical machines are oversized for safety, become less efficient and the mass gain is reduced. That is why the understanding of the behavior, or characterization, of magnetic materials used in electrical machines under non-ideal conditions is essential. On the other hand, it is necessary to improve the iron loss models in order to make their prediction efficient and to optimize the electrical machine modeling. The more precise their prediction, the more the factors influencing the losses will be determined. It will then be possible to envisage a more global optimization of the electromechanical chain. This thesis is a first step towards this global integration. The magnetic material characterization was done under various conditions. First, one-dimensional flux density B have been studied. The influence of their spectrum on iron losses was the major purpose of this characterization: amplitude or frequency influence in the case of sinusoidal fields and then harmonic frequency or harmonic phase influence for more complex spectrum. Iron losses are very sensitive to these parameters. Then, the proposed loss modelling goes through a reconstruction of the hysteresis cycle. Therefore, it consists in predicting B from the H field. Based on Play model, this scalar quasi-static modelling has shown its accuracy and predictability. However, being scalar and quasi-static prevent the model from any time-dependence. An analytical model of eddy currents and a dynamization proposal has been developed. With an eddy current model, frequency effects would be taken into account and thus would complete the quasi-static model.

Magister Artium (Human Ecology) - MA(HE) / Iron deficiency anaemia is the most common abnormality of the blood in childhood (Karabus 1987). If the quantity of iron lost by the body exceeds iron intake, the body will draw on its iron reserves to counterbalance this deficit. However, the continuance of an iron imbalance will eventually lead to a reduction in body iron stores. Because iron forms an integral component of the oxygen transport mechanism of the body, it is understandable that the functional capacity of this system will be compromised under conditions of iron deficiency. A deficit in oxygen transport capacity will presumably indicate a decreased capacity to persevere in the face of continuing strenuous physical activity. The decrement in physical aerobic working capacity (maximal oxygen consumption) will largely be indicative of the decrease in oxygen transport capacity. Routine haemoglobin determinations carried out in the outpatient department of the Red Cross War Memorial Children's Hospital in Cape Town showed that many Coloured and African pre-schoolgoing children had abnormally low haemoglobin levels which occurred as a manifestation of iron deficiency anaemia (Lanzkowsky 1961). In another similar but more recent study also in the Cape Peninsula, Lamparelli et al. (1988) showed that the prevalence of iron deficiency anaemia in Coloured and African children was 15.5 % and 36.0 %, respectively . In this study, the condition of iron deficiency anaemia was particularly pronounced in urban Coloured children. In both these studies done in the Western Cape, the majority of Coloured children were classified as coming from the lowest socioeconomic income group in the community. In the majority of studies concerning the relationship between socioeconomic status and iron deficiency anaemia, it is often stated that low socioeconomic circumstances are significantly correlated to low blood haemoglobin levels (Expert Scientific Working Group 1985; Lanzkowsky 1959; Lanzkowsky 1961; World Health Organization 1972; World Health Organization 1975).

Στις ηλεκτρικές μηχανές ο υπολογισμός των απωλειών και οι μηχανισμοί που τις προκαλούν αποτελούν ένα πολύ απαιτητικό αντικείμενο μελέτης. Τα τελευταία χρόνια καθώς αυξάνεται η ανάγκη για ολοένα και πιο αποδοτικές μηχανές μεγάλο κομμάτι της έρευνας έχει επικεντρωθεί στον υπολογισμό των απωλειών τους και πιο συγκεκριμένα στον υπολογισμό των απωλειών σιδήρου. Οι απώλειες σιδήρου ή αλλιώς απώλειες πυρήνα αποτελούν σημαντικό μέρος των απωλειών μια μηχανής, ταυτόχρονα όμως ο υπολογισμός τους εμφανίζει ιδιαίτερη δυσκολία. Στην παρόυσα διπλωματική εργασία η προσπάθεια επικεντρωνεται στον υπολογισμό αυτών των απωλειών σε μια ασύγχρονη μηχανή με διάφορες μεθόδους. Πιο συγκεκριμένα, στο πρώτο κεφάλαιο γίνεται μια εισαγωγή στα σιδηρομαγνητικά υλικά και στις ιδιότητες τους. Αρχικά παρουσιάζεται το φαινόμενο της μαγνήτισης και του κορεσμού. Στη συνέχεια μελετάται το φαινόμενο της υστέρησης και οι ιδιότητες της που παίζουν καθοριστικό ρόλο στις απώλειες του πυρήνα της μηχανής, αλλά και το φαινόμενο των δινορευμάτων. Στο δεύτερο κεφάλαιο μελετώνται οι απώλειες της μηχανής. Με ποιό τρόπο δηλαδή το φαινόμενο της υστέρησης και των δινορευμάτων πρoκαλούν απώλειες στη μηχανή και με ποια μορφή εμφανίζονται. Παρουσιάζονται ακόμα οι μηχανισμοί που συνδέονται με τις απώλειες χαλκού, επιδερμικό φαινόμενο και φαινόμενο γειτνίασης και ο ρόλος τους. Παρουσιάζεται επίσης μια βιβλιογραφική έρευνα σχετικά με τις διάφορες μεθόδους που χρησιμοποιούνται για τον υπολογισμό των απωλειών σιδήρου. Το τρίτο κεφάλαιο αποτελεί ουσιαστικά μια εισαγωγή στα ηλεκτρονικά ισχύος και πιο συγκεκριμένα στον αντιστροφέα τάσης με τεχνική PWM. Σημαντικός θεωρείται ο τρόπος με τον οποίο διαμορφώνεται η τάση εισόδου στη μηχανή, αλλά και η μορφή της, καθώς επηρεάζει άμεσα τις απώλειες σιδήρου της μηχανής. Στο τέταρτο και τελευταίο κεφάλαιο βρίσκουν εφαρμογή όλα τα παραπάνω. Η εργασία γίνεται με τη βοήθεια ενός μοντέλου πεπερασμένων στοιχείων, δύο διαστάσεων, μιας ασύγχρονης μηχανής βραχυκυκλωμένου κλωβού. Αρχικά η μηχανή τροφοδοτείται από μια ημιτονοειδή τάση είσόδου. Υπολογίζονται οι απώλειες χαλκού και στη συνέχεια οι απώλειες σιδήρου με τη βοήθεια υπολογιστικών μεθόδων ανάλυσης του μαγνητικού πεδίου σε σειρές Fourier. Τέλος μελετάται η μορφή του μαγνητικού πεδίου σε διάφορα σημεία της μηχανής και οι απώλειες που εμφανίζεται σε κάθε στοιχείο του μοντέλου ανά περίπτωση. Τα βήματα αυτά επαναλαμβανονται τροφοδοτώντας αυτή τη φορά τη μηχανή μέσω αντιστροφέα τάσης με τεχνική PWM. Συγκρίνοντας τα αποτελέσματα από κάθε περίπτωση εξάγονται σημαντικά συμπεράσματα για τις απώλειες της μηχανής και τη συμπεριφορά των μηχανισμών που τις προκαλούν. / In electrical machines the calculation of loss and the mechanisms that cause them are a very demanding subject of study. Recently, the increasing need for ever more efficient machines has made the research focus on the calculation of their losses and more specifically the calculation of the iron losses. The iron losses or core losses, constitute an important part of the total machine losses, but also their calculation is particularly difficult. In this thesis we focus on the calculation of these losses in an asynchronous machine using various methods. More specifically, the first chapter is an introduction to the properties of ferromagnetic materials. First, we study the phenomenon of magnetization and saturation and then we examine the phenomenon of hysteresis and its properties which play a crucial role in the core losses of the machine. Finally we study eddy current phenomenon. In the second chapter we discuss the losses of the machine. In which way the phenomenon of hysteresis and eddy currents generate losses in the machine and the form in which they appear. Also presented are the mechanisms associated with the copper losses, skin effect and proximity effect. Also shown is a literature survey on various methods used to calculate the iron losses. The third chapter is essentially an introduction to power electronics, and more particularly to the PWM technique. Important in this chapter is the way in which the input voltage to the machine affects the iron losses. In the fourth and final chapter we produce results of the above theory using simulation methods. The work is done using a finite element model in two dimensions of a squirrel cage asynchronous machine. Initially the machine is fed by a sinusoidal input voltage. Firstly copper losses are calculated and then the iron losses with the help of computational methods which analyze the magnetic induction in Fourier series. Finally, we study the shape of the magnetic field in different parts of the machine and the losses occurring in each element of the model in each case. These additional losses are known as rotational core losses. These steps are repeated, this time powering the machine via inverter supply using the PWM technique.