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Abstract. The comparative study of electric machines has been in vogue due to the growing demand for electromechanical converters with maximum possible efficiency. In this scene, the switched reluctance machines have proven to be competitive. Comparative studies between these machines and the already established induction machines can be easily found in the scientific literature, but studies on various configurations of the switched reluctance machines are not as widespread. This paper shows the modeling, simulation and presents a comparative study of two Switched Reluctance Machines to a single phase (6x6) and three phase (6x4). Aspects of construction, drive and efficiency are discussed in order to find advantages and disadvantages to each of these machines.

This paper reports on the switched reluctance machine operating as motor/generator (SRM/G) excited through an external power source. The half-bridge static converter topology is used to drive the machine in either modes of operation. Transition from motor to generator mode is firstly discussed and results from both simulation and experimental tests are included. Operating as generator, the output generated voltage is a function of the phase magnetization level during excitation; therefore, by controlling the phase excitation level, the output voltage is also controlled. Three output voltage control techniques are proposed and analyzed: 1-Variable Angle (VA), effected by controlling the phases turning off angles with a fixed DC link excitation voltage; 2-Chopping (CH), attained by chopping the DC link supply during the phases magnetization while keeping a fixed conduction period; and 3-Variable Link (VL), reached by controlling the DC link excitation voltage by means of a DC-DC buck converter in a fixed conduction period. For the experimental work, full digital control is implemented. Results obtained with the implementation of the output voltage control techniques are presented. Relative performance comparison is included, showing that the CH followed by VL strategy brings the best outcome.

Resumo-O objetivo deste artigo é propor uma estratégia de melhoria da conversão eletromecânica de energia do Gerador a Relutância Variável (GRV). Esta estratégia é implementada através do controle da magnetização de cada fase do GRV. Para isto, foi utilizado um compensador do tipo PI para controlar a tensão na carga atuando no ângulo de abertura da chave superior do conversor em ponte assimétrica, half-bridge (HB), o que adiciona uma etapa de roda-livre às etapas de operação do conversor. No sentido de verificar a eficiência da estratégia proposta, foram desenvolvidas duas ações de trabalho. A primeira foi o desenvolvimento da simulação matemática do GRV no ambiente Matlab/Simulink®, acionado pela estratégia proposta. Na modelagem do GRV utilizou-se a abordagem não-linear, que inclui a representação da saturação do circuito magnético através do conceito de indutância incremental modelada através da Série de Fourier. Toda a estratégia de controle, o compensador PI, o conversor e os demais circuitos foram também simulados. A segunda foi o desenvolvimento de uma bancada experimental contendo um GRV de 5,0 kW, uma máquina primária, o conversor HB, circuitos de controle e uma carga resistiva. Foram realizados testes para diversos pontos de operação, tanto no modo de operação tradicional como para a estratégia proposta. Os resultados, de simulação e experimentais, apontam para melhoria advinda da estratégia proposta. Convém ressaltar ainda, que, para este experimento, foram utilizados apenas componentes analógicos, o que reduziu significativamente o custo total do sistema de acionamento.

This article describes the characteristics of the Brazilian electric system, whose main generation source is hydroelectricity and how the country made stable and economic the supply of energy on a large scale, managing the uncertainties of this type of source. The study of how this country has been dealing with the variability of supply of each of their enterprises, using the storage capacity and deployment of the country's energy integration can be a source of inspiration for other countries on how to handle the various issues that arise in the integration between different energy sources.