Continuous PWM Algorithms for Direct Torque Control of Induction Motor

The present work describes the Direct Torque Control of Induction motor Drive using various Simplified Space vector Based Random PWM Algorithms for Reduction of Total Harmonic Distortion and Acoustical Noise. To reduce the complexity involved in the classical SVPWM algorithm and to improve the performance of CDTC in terms of ripples and THD in this research a simplified SVPWM is initiated. To reduce the acoustical noise and total harmonic distortion of the drive due to the large amplitudes of dominating harmonics around the multiples of switching frequency at all Modulation Indices various Random PWM Algorithms namely RZSDPWM DZRCDPWM HRPWM and VDRPWM Algorithms are implemented using MATLAB/simulink Simulation for the Induction motor drive and the resulting THD and Noise are compared with the conventional Drive. It is observed that the proposed RPWM algorithms gives spread spectra and hence give less acoustical noise when compared with SVPWM algorithm based DTC. Further the proposed RPWM algorithms using the concept of imaginary switching times results in superior performance in terms of acoustical noise and THD over wide range of modulation indices.