Fuzzy Estimators for Tuning the Stator Resistance in Direct Torque Control by Using three level Inverters

Nowadays, induction motors are extensively used forthe most reliable electrical machines. This is due to its excellentcharacteristics such as high efficiency, high overloadcapability, cheap, robust and less prove to any failure at highspeed. Although DTC is getting more and more popular, it alsohas some drawbacks, such as the high torque and flux ripplesand An accurate estimation of stator resistance is so importantespecially during the operation of an induction motor due tovariation in the stator resistance and the temperature of theworking machine. This paper proposes a modified DTCscheme to minimize the ripples in flux and torque by usingthree level inverters in Induction Motor, and to improve thesystem performance at low speed a fuzzy resistance estimatoris proposed to eliminate the error due to the change in statorresistance. Simulation results by Matlab show the effectivenessof the method.

Keywords:

Direct Torque Control (DTC) , three-levelinverters , Ripple , Induction Motor , Stator Resistance Estimator , Fuzzy logic