Fuzzy Logic Based Life Estimation of PWM Driven Induction Motors

Pulse-width modulated (PWM) adjustable frequency drives (AFDs) are extensively used in industries for control of induction motors. It has led to significant advantages in terms of the performance, size, and efficiency but the output voltage waveform no longer remains sinusoidal. Hence, overshoots, high rate of rise, harmonics and transients are observed in the voltage wave. They increase voltage and thermal stresses; resulting into accelerated insulation aging. This paper presents the application of fuzzy logic to life estimation of PWM driven induction motors. Insulation stress parameters are experimentally computed for wide range of switching frequency and used in fuzzy logic based life estimation algorithms. The results obtained with the fuzzy expert system show a performance approaching that attainable for the life model based on the inverse power law.