A COMPREHENSIVE REVIEW OF PWM TECHNIQUES FOR MULTILEVEL INVERTER-FED INDUCTION MOTOR DRIVES

Abstract

Induction motors are widely used in industrial applications because they are simple, reliable, and economical. However, controlling the speed and torque of an induction motor efficiently is an important challenge. Power electronic inverters are commonly used to control the voltage and frequency supplied to the motor. Conventional inverters may produce harmonic distortion, switching losses, torque ripple, and poor output voltage quality. Multilevel inverters have been developed to overcome many of these problems by producing an output voltage with multiple levels. This results in a waveform closer to a sinusoidal waveform and reduces harmonic distortion. Pulse Width Modulation (PWM) techniques play an important role in controlling multilevel inverters. Different techniques such as Sinusoidal PWM (SPWM), Space Vector PWM (SVPWM), Trapezoidal PWM, harmonic-injection PWM, discontinuous PWM, adaptive PWM, and intelligent control-based PWM have been studied for induction motor drives. The reviewed studies show that multilevel inverter systems can provide better voltage quality, lower Total Harmonic Distortion (THD), improved speed response, and better motor performance. However, advanced techniques may increase controller complexity and computational requirements. This review presents a simple comparison of different PWM techniques used with multilevel inverter-fed induction motor drives. The advantages, limitations, harmonic performance, switching losses, speed control, and dynamic response of different methods are discussed. The review also identifies adaptive PWM as a promising approach for achieving better performance under varying load conditions.