T-Type Multilevel Inverter based Performance Improvement of Induction Motor

In this paper the performance of the induction motor (IM) using direct torque control (DTC) strategy has been examined. The traditional configuration of this strategy was compared with the modified structure based on three level T-type inverter (TLTI). The performance comparison process aims to inspect the effect of increasing the number of voltage levels on the behavior of this control system. Moreover, the other objective in this work is to employ a multilevel inverter structure that possesses a reduced component count. Software implementation of the DTC algorithm was obtained using MATLAB/Simulink program. The basic structure of the DTC is utilized for performance verification of the induction motor based on conventional inverter. When the DTC algorithm employs T-type inverter, a slight modification was needed in the algorithm structure in order to make the most of the advantages of the three level inverter. The modification included an increase in the levels of the comparators of the flux and torque, as well as increasing the number of sectors. The performance comparison was focused on the evaluation of the flux and torque ripples as well as the stator current quality points of view. The results of the simulation results showed a noticeable improvement of the IM behavior when using the TLTI. A significant reduction of the ripples and enhancing the stator current quality have been achieved.