Comparative analysis of 2-Level and Multi-Level Inverter fed coupled IM drives based on V/f and DTC techniques

For industrial sectors involving coupled induction motor drives, control of speed/torque is an utmost critical issue especially in dynamic conditions. Considering this aspect, there is a dire need of a flexible and efficient control which could best fit in the scheme of coupled drive operation. In this paper an effort has been made to explore different facets of speed/toque control for coupled induction motors based on traditional scalar (Volt/Hz) and advanced vector (Direct Torque) techniques. Also in order to facilitate improvements in terms of harmonic contents and power losses, it has been proposed to replace traditional 2-Level Inverter in Induction Motor drive with an advanced Reversing Voltage Multi Level Inverter (MLI) topology providing 5-Levels of output phase voltage. Based on the simulation study for both the control strategies in MATLAB/Simulink, it has been shown that harmonic distortions present in the fundamental output voltage of a coupled drive fed by Multilevel Inverters are comparatively less when compared to its 2-Level counterpart. These reduced distortions are in-turn responsible for toning down filtering requirements at the input of motor, thereby enhancing the efficiency of drive system.