A Novel Space Vector Pulse Width Based High Performance Variable Structure Direct Torque Control Evaluation of Induction Machine Drives

Abstract

In this study, direct torque control (DTC) of induction motor is evaluated based on space vector modulation (SVM).DTC is a method to control machine with utilizing torque and flux of motor controlled.Direct Torque Control (DTC) is known to produce fast response and robust control in ac adjustable speed drives. However, in the steady-state operation, notable torque, flux and current pulsations occur. In this paper, a new direct torque and flux control strategy based on Variable-Structure Control (VSC) and Right Aligned Space Vector Modulation (RASVM) is proposed for sensorless induction motor drives. The principles of variable structure control (Sliding mode controller), DTC and less commutation space vector modulation are combined to ensure high performance operation, both in the steady state and under transient conditions. Three new VSC schemes are designed following the DTC voltage control philosophy. SVM-DTC is a technique to reduce the ripple. SVM techniques have several advantages that are offering better DC bus utilization, lower torque ripple, lower total harmonic distortion in the AC motor current, lower switching loss, and easier to implement in the digital systems. Simulation results from the classical and improved DTC are presented and compared. Result shows that the torque, flux linkage and stator current ripple are decreased with the improved DTC.