DIRECT TORQUE CONTROL OF INDUCTION MOTOR USING SPACE VECTOR MODULATION TECHNIQUE

Abstract

The control and estimation of ac drives in general are considerably more complex than those of dc drives, and this complexity increases substantially if high performances are demanded In recent years, the application field of Direct Torque Control (DTC), a variation of vector control, of induction machines has greatly increased in the areas of the traction, paper and steel Industry, and so on. Direct Torque Control is one of the actively researched control schemes, which is based on the decoupled control of flux and torque providing a very quick and robust response with a simple control construction in ac drives. The main limitation of the conventional DTC is large torque ripple and variable switching frequency. These disadvantages can be overcome by using Space Vector Modulation (SVM). SVM can be implemented in two ways to generate pulses to control the output voltage of the inverter. SVM generates pulses by using Voltage Vector reference in one approach and using Flux error Vector in another approach. Direct Torque Control of Induction Motor using Flux Error based SVM has been adopted for the present study. The torque ripple and Flux error can be reduced by using Flux error based SVM as compared to Voltage Vector reference based SVM. In present work, these comparative features have been highlighted, through MATLAB simulation.