GA - based optimization of total harmonic current distortion and suppression of chosen harmonics in induction motors

In this study, a genetic algorithm optimization technique is applied, to minimize the total harmonic current distortion (THCD) in induction motors fed by high power inverters, based on an approximate model. That is, having defined a desired fundamental output voltage, optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for two cases of 3 and 5 switching instants in the first quarter period of PWM waveform are presented. In the sequel, considering that the torque pulsation is mainly affected by the presence of low-order harmonics, the fifth, seventh, 11th, and 13th order harmonics (in the case of 5 switching angles) are limited at some pre specified values, to have the THCD optimized and the output voltage regulated concurrently