A New Direct Torque Control Algorithm for Torque and Flux Ripple Reduction

Abstract

In this study, a novel direct torque control (DTC) algorithm is developed to decrease torque ripple, electromagnetic noise and harmonics in the three phase squirrel caged induction motors. The space vectors of the conventional DTC method, the position of the stator flux vector and deviation from the reference flux are utilized to construct the new algorithm. Switching time of the vectors in the proposed algorithm is determined from a switching table which is based on the flux error. Switching time pairs in the table are selected using the flux error and the position of the sector. This table eliminates need for complex mathematical operations to determine the switching time of the space vectors in the induction motors and maximizes the performance of the algorithm. The algorithm is simulated and tested by an experimental setup. Simulation and experimental results suggest that the proposed algorithm decreases torque ripple and current harmonic and it has adequate dynamic and steady-state torque performance. Compared to the conventional DTC, the new algorithm has lower EMI noise level