Analysis of Direct Torque Controlled Techniques for Induction Motor Drives with Two Level Inverter

Abhishek Verma, Yogesh Kumar Chauhan

Abstract— The objective of the present work is to obtain the reduced torque ripples, harmonics distortion. Duty Ratio Control has been developed to improve the torque performance and to obtain the voltage space vector required to compensate the flux and torque errors. In conventional Direct Torque Control (DTC), the selection of flux linkage and electromagnetic torque errors are made within the respective flux and torque hysteresis bands, in order to obtain fast torque response, low inverter switching frequency and low harmonic losses. However, DTC drives utilizing hysteresis comparators suffer from high torque ripple and variable switching frequency. As in duty ratio control technique, instead of applying a voltage vector for the entire switching period, it is applied for a portion of the switching period and the zero switching state is applied for the rest of the period the ripples is considerably reduced. In this paper the simulation of different DTC schemes (Conventional DTC and Duty Ratio Control DTC) has been carried out using MATLAB/SIMULINK and the results are compared.