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.

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.

Made available in DSpace on 2016-12-12T17:38:37Z (GMT). No. of bitstreams: 1 ILTON ANCELMO PEREIRA JUNIOR.pdf: 6854626 bytes, checksum: 8fdf9667f4e840b4dc298f1e9605bf2d (MD5) Previous issue date: 2011-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This master thesis introduces a study about the influence of frequency variation induced in the magnetic properties of materials. Experiments are accomplished in the Epstein frame or Epstein square, the measurements are being acquired through a data acquisition system PC-based, which is handled through a software developed in LabVIEW. As results, we have the magnetization curve, hysteresis loop and specific losses for several preset frequencies, and the harmonic distortion evaluation in current and voltage signals during the trial. The end of the essay presents a methodology able to accomplish the harmonics cancellation generated by the steel saturation, applying a voltage source having adjustable harmonic voltages. / Esta dissertação apresenta um estudo sobre a influência da variação da frequência nas propriedades magnéticas dos materiais. Os ensaios são realizados em quadro de Epstein, sendo as medições obtidas através de um sistema de aquisição de dados baseado em PC, o qual é controlado por um software desenvolvido em LabVIEW. Como resultados têm-se a curva de magnetização, a curva de histerese e as perdas específicas para diversas frequências pré-selecionadas, sendo avaliadas as distorções harmônicas de tensão e de corrente, durante os ensaios. Ao final é apresentada uma metodologia capaz de realizar o cancelamento das harmônicas geradas pela saturação do aço, através de uma fonte de tensão com ajuste de harmônicos.

This thesis deals with the analysis of magnetic losses in electrical machines and the possibilities of their measurement. Magnetically soft and hard materials are very prone to changing magnetic properties. They can be changed simply by changing the temperature of the material or different stresses induced in the material, resulting in different results. These changes are important to keep in mind when an electric machine is being designed. The original parameters of the affected materials can be restored by annealing or grinding. These methods release the induced stresses within the material. Due to these effects, it is also important to know how to measure magnetic parameters. Each way has its own specifics and has a certain error of the measurement. When the machines for higher efficiency, rpm or higher temperatures are designed, it is advisable to know how their magnetic properties changed. This thesis deals with the properties of different materials, their measurements and finally simulation of the chosen electric machine with the application of the measured results.