Performance Improvement in Direct Torque Control of Induction Motor Fed by Three Level Inverter

摘要

The direct torque control technique is more useful technique in ac drives to obtain high performance torque control. This paper presents Direct Torque Control Of Induction Motor using 3-level Inverter for minimization Of Torque Ripple. The DTC drive contains a pair of hysterisis comparators, flux and torque estimator and voltage vector selection table. Conventional 2-level DTC of Induction Motor has the drawbacks of high torque and flux ripple and variable switching freaquency. The variable switching frequency may excite resonant dynamics in the load. The drawbacks of DTC can be overcome by one of the improved technique Space Vector Modulation. The SVM-DTC technique improves the torque performance and maintain the switching frequency constant. The SVM-DTC of induction motor fed by Three Level Inverter is more accurate technique for reduction of torque, flux and stator current ripples lower common mode voltage, lower dv/dt, lower harmonic in output voltage and current, greater number of levels in the output voltage waveforms, and reduced voltage on the power switches as compared to the classical DTC, and SVM-DTC of induction motor fed two level inverter. The proposed scheme is described clearly and simulation results are reported to demonstrate its effectiveness. This entire control scheme is implemented with Matlab/Simulink.