Simplified Space Vector Based Discontinuous Variable Delay Random PWM Algorithms for Reduced Total Harmonic Distortion in Induction Motor Drive

The direct torque control provides precise and quick response and the SVPWM algorithm gives good performance for control of induction motor drive, but these algorithms produces more acoustical noise resulting in increased distortion of harmonics. To reduce these effects various PWM techniques were used in recent. Though the deterministic pulse width modulation (PWM) algorithms give good performance, it also results in more harmonic distortion. Hence, to minimize these anomalies of the drive, this paper presents discontinuous variable delay random pulse width modulation algorithms for direct torque control of induction motor drive. The proposed algorithms randomizes the switching periods by varying the delay of switching cycles with respect to corresponding sampling cycles. In the proposed variable delay random pulse width modulation (VDRPWM) algorithm, the effective time is determined using the concept of imaginary switching times which are proportional to the instantaneous phase voltages in order to avoid the requirement of angle and sector identification. To validate the proposed schemes, simulation studies has been carried out on space vector controlled induction motor drive based on discontinuous variable delay random pulse width modulation algorithms using MATLAB/SIMULINK. Further, the simulation results are presented and compared with conventional DTC and space vector based direct torque control of induction motor drive.