V/f control of Induction Motor by sine PWM control using Inverted Sine Carrier

Sine PWM (SPWM) is a carrier-based modulation technique. It is widely used with power electronics converters, especially for the control of voltage source inverter (VSI). It is dominant because of its easy implementation, capability to efficiently regulate voltage and current, and reduce the harmonics from the output of the inverter. Still this method suffers from the limitation of reduced power output in the over-modulation region. In 2007 R.Nandhakumar et al. proposed a novel approach for sine PWM using Inverted sine carrier PWM (ISCPWM) method. They have shown the advantages of their proposed method in terms of increased duty cycle and reduced harmonics for varying values of Modulation Index (m) and carrier frequency. In this research, ISCPWM method has been used instead of conventional SPWM method for the V/f control of Induction Motor. In the paper it shown that, using ISCPWM method the response time of motor to speed change command is reduced and the torque ripples are reduced. The proposed V/f control using ISCPWM method has been simulated in matlab and the results are compared with conventional triangular wave based SPWM method. The results of motor speed, torque, and total harmonic distortion (THD) for different values of load torques for both the techniques are compared.