IM Drive using Fuzzy Logic Based DTC Technique

This paper presents a direct flux and torque control (DTC) of three phase induction motor drive (IMD) using PI and fuzzy logic controllers (FLC) for speed regulator (SR) and low torque ripples. This control method is based on DTC operating principles. The DTC is one of the most excellent direct control strategies of stator flux and torque ripples of IMD. The key issue of the DTC is the strategy of selecting proper stator voltage vectors to force stator flux and developed torque within a prescribed band. Due to the nature of hysteresis control adopted in DTC, there is no difference in control action between a large torque error and a small one. This results in high torque ripple. It is better to divide the torque error into different intervals and give different control voltages for each of them. To deal with this issue a fuzzy logic controller has been introduced. The main drawback with the conventional DTC of IMD is high stator flux and torque ripples and the speed of IMD is reduced under transient and dynamic state of operating condition. This drawback is reduced by the proposed system, the speed is regulated by PI controller and torque is controlled by fuzzy logic controller. The amplitude of the reference stator flux is kept constant at rated value. The simulation results of proposed DTC shows the low stator flux linkage, torque ripples and good speed regulator than conventional DTC technique using MATLAB/SIMULINK. KeywordsDirect Torque Control (DTC), Fuzzy Logic Control (FLC), Induction Motor Drive (IMD), Space Vector Modulation (SVM).