Improved dynamic performance of direct torque control at low speed over a scalar control

Abstract

This paper presents the scalar control as well as direct torque control for speed control of induction motor. The scalar control is an easy to implement but it gives poor dynamic response. In addition to the scalar control the space vector pulse width modulation (SVPWM) is used for effective utilization of the dc-link voltage i.e. SVPWM is having the good voltage regulation and reduces the considerable harmonics in voltage as well as current of the inverter. The dynamic response of the induction motor is improved using direct torque control with SVPWM technique. The performance of induction motor with scalar control and direct torque control is simulated in the Matlab environment and compared their response under similar operating conditions. The dynamic performance, the speed regulation, THD in the current, and the torque distortion of induction motor are effectively improved with direct torque control (i.e. lesser transient time) even while applying the load in comparison to scalar control.