Reduced Torque Ripple DTC of Induction Motor by Modifying Vector Table

Abstract

Direct Torque Control is a control technique used in AC drive systems to obtain high performance
torque control. The conventional DTC drive contains a pair of hysteresis comparators, a flux and torque estimator and a
voltage vector selection table. The torque and flux are controlled simultaneously by applying suitable voltage vectors,
and by limiting these quantities within their hysteresis bands, de-coupled control of torque and flux can be achieved.
However, as with other hysteresis-bases systems, DTC drives utilizing hysteresis comparators suffer from high torque
ripple and variable switching frequency.
For solution of these problems, in present work an attempt has been made to modify switching vector table by
using like SVPWM voltage vector pattern. By controlling the time of this SVPWM like vector, torque slop can be
controlled. Modification of switching vector table results in reduced torque ripple and application of SVPWM like vector
pattern may gives regular switching frequency. It is expected that modifications made in this work may result in lower
electromagnetic torque ripple.