Simulation studies on 2/3/5-level DTC based speed control of IM drive in four quadrant Operation

Simulation studies have been done to compare the speed and torque dynamics as well as steady state responses of an Induction Motor drive fed through the 2/3/5-level Voltage Source Inverter (VSI) using Direct Torque Control (DTC) technique in all the four quadrants. Reference speed and load torque has been generated to realize four quadrants through up-hill, downhill in forward and reverse directions. Matlab programming has been successfully implemented for 12 sectors, 2/3 and 5-level VSI using 8, 27 and 64 voltage vectors respectively. Flux and torque logic states have been taken as 2-3, 3-5 and 7-7, which results in switching combinations of 36, 180 and 588 for the 2/3 and 5-level VSI respectively. It has been observed that for the fixed tuned value of proportional and Integral (PI) control, the torque and flux variance for 5-level decreases by 91.6% and 38.2% respectively as compared to 2-level DTC based VSI. The steady state speed fluctuation improves by 71.42%.