Torque ripple reduction in five-phase direct torque controlled induction motor

This paper presents the torque ripple reduction in the direct torque controlled (DTC) five phase induction motor (IM). The ripples are directly related to the hysteresis band of the controller in torque and flux loops within the operating switching frequency limits. It is proposed to increase the switching frequency by dither signal injection into the torque and flux control loops. A conventional DTC control of five phase model is modified by superimposing a high frequency and small amplitude triangular waveform into torque and flux error. The operation of five phase induction motor within the operating speed range indicates the reduction in the torque ripple and improves its performance in the low speed region. It is observed that the torque ripple is reduced by 30% and improvement in the total harmonic distortions (THD) of current. The overall dynamic performance improvement is indicated through MATLAB/SIMULINK simulation.