Performance Analysis of Conventional Direct Torque Control Strategy for Wide Range Speed Control of Induction Motor Drives

Abstract

Decoupled control of induction motor drives is possible using Direct Torque Control (DTC) method which is very simple control approach paralleled to field oriented control. It is very good alternative for applications like traction or automobile where direct torque control is needed. But speed control from zero to rated or even beyond rated speed is required in such applications. Torque ripples, variable switching frequency and poor low speed performance are well known problems of DTC strategy. Analysis of DTC IM drives for wide range speed control is carried out in this paper to check suitability of the scheme and to find causes of inferior performance. Matlab/Simulink model of direct torque controlled IM drive for closed loop speed control is created and results are obtained for different conditions relevant for wide range speed control applications like automobile and traction. This analysis yields extremely important information to improve the performance of DTC IM drives for wide range speed control. Keywords: DTC, electric vehicle, traction motors, induction motor drives