DTC-IM drive with 5-level hybrid cascaded h-bridge inverter

Due to control simplicity and easy applicability DTC has become popular and adopted in many industrial applications. But it still suffers from a few drawbacks like- comparatively large torque ripple in a low speed range and its performance is highly depended on speed of the motor and hysteresis bands of torque and flux ripple. To address these problems, this paper represents a direct torque control (DTC) strategy for induction motor (IM), utilizing hybrid cascaded H-bridge multilevel inverter (HMLI) extending the idea of basic two level DTC proposed by Takahashi. Simulation results shows that the DTC drive performance has been considerably improved in terms of lower torque and flux ripple and less THD. These have been evaluated by simulation and compared with the basic DTC developed by Takahashi and other DTC proposed to date.