Performance of Direct Torque Controlled Induction Motor Drive by Fuzzy Logic Controller

Abstract

In this paper, Direct Torque Control (DTC) of three phase Induction motor (IM) using a fuzzy logic controller (FLC) is presented. Direct torque controller (DTC) is used to achieve good transient response with latent features an induction motor drive.  The conventional DTC produces Flux/Torque ripple and variable switching frequency. The FLC is proposed to achieve smooth ripple free torque and speed performance. In this proposed technique, the speed error and change in speed error are processed through the FLC. The proposed fuzzy logic controller calculates the appropriate inputs variables for the DTC loop using logic variables.  The FLC produces the reference torque for the torque control loop. The electromagnetic torque is controlled to control the speed of the induction motor. Space Vector Pulse Width Modulation (SVPWM) is used to generate gate pulses for the three-phase Voltage Source Inverter with constant switching frequency. The proposed FLC and conventional PID controller system are modeled in MATLAB/SIMULINK and simulation results are compared in terms of torque ripples and current harmonics.  The effectiveness of the proposed algorithms is investigated by hardware implementation by PIC microcontroller. Total Harmonic Distortion (THD) analysis for load current is also carried out in this paper