A precise induction motor speed estimator, based on a fixed carrierfrequency signal

摘要

A speed estimation method, based on the introduction of a constantfrequency carrier signal, is presented. This frequency carrier signalproduces a constant speed rotating field from which the speedinformation in a wide range is obtained. The speed is estimated throughthe detection of irregularities in the rotor. These irregularitiesgenerate frequency pulsations proportional to the rotor speed, which areindependent of the parameters of the machine. Because these signals areextremely low, special electronic circuits, implemented with analogmultipliers and filters, have been designed, and they are able tomeasure very low speed values. Computer simulations and some experimentshave been carried out, and they have shown that it is possible tomeasure speeds as low as 20 RPM