Diseño de prototipo de fuente controlada de voltaje para motor trifásico, de rotor bobinado
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In the process of distribution of electric energy, the companies that take it upon to generate it and distribute it should watch over for the better utilization of the same, giving each user the same quality of the product and avoiding the maximum the waste and the losses. In order to achieve it, the companies of generation and they of distribution apply regulations and fines to the big companies and factories that they don't fulfill certain ranges in the utilization of the electricity. One of the parameters to respect is the power factor (pf), the phase difference that is produced between the voltage vector and the current vector. In the case of the factories, that in their majority relies on motors (inductive element), a backwardness of the current is produced with concerning the voltage, producing loss in the lines of transmission, for it should be corrected this problem. With the utilization of semiconductors of capacity, it are succeeded in getting increase the efficiency in the utilization of the resources already available, so much in the part of control like in the own element managed by these. Like for example: the utilization of changer frequency for the starts of motors, the utilization of rele of state solid. In this case in particular in the creation of a source of voltage of direct current, designed with thyristors to have the characteristic that is controlled. It with her get excited the rotor of a motor triphase, in order to have control on the value of the fp. In this process of rectification for tall current should look after another of the parameters that are regulated, like him is the generation of harmonics in the line, the which degenerate the quality of the form of wave sinusoidal that gives the company. In order to avoid this problem it are proceeded to carry out a design of two triphase rectifiers, formed by six thyristors (converter of 6 pulses), that is connected in parallel to achieve current output, forming the called converter of 12 pulses, that reduces the quantity of harmonics. In order to could interconnect the two converter of 6 pulses, it are needed to make by means of a transformer of it couple and to can make the converter of twelve pulses, the transformer that feeds at two of 6, it is of characteristic very special, with a winding primary in connection wye and, two windings secundaries, one connected in wye and the other in star, to achieve the good operation of the group. Also the part of control of shooting of the thyristors should be adequate to this system of 12 pulses.
Proyecto de Graduación (Bachillerato en Ingeniería Electrónica) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería Electrónica, 2002