A FAMILY OF VARIABLE DELAY RANDOM PWM ALGORITHMS FOR DIRECT TORQUE CONTROLLED INDUCTION MOTOR DRIVES FOR REDUCED HARMONIC DISTORTION AND ACOUSTICAL NOISE
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Though the deterministic pulsewidth modulation (PWM) algorithms give good performance, it generates more acoustical noise. Hence, this paper presents a family of variable delay random pulsewidth modulation (VDRPWM) algorithms for direct torque controlled induction motor drives for reduced total harmonic distortion (THD) and acoustical noise. The proposed algorithms randomizes the switching periods by varying the delay of switching cycles with respect to corresponding sampling cycles. This randomization of switching periods has a mitigating effect of the acoustic and electromagnetic noise emitted by the supplied system. Moreover, to reduce the computational effort and complexity involved in the PWM algorithms, the proposed VDRPWM algorithms are developed by using the concept of imaginary switching times, which are proportional to the instantaneous phase voltages. Hence, the implementation of the proposed algorithm is simpler. To validate the proposed PWM algorithms, simulation studies have been carried out and results are presented. The simulation results confirmed the features of proposed PWM algorithms.