Vector Control of Induction Motor with Variable Sampling Frequency Random PWM Techniques for Reduced Harmonic Distortion

Abstract

This paper presents random PWM (RPWM) methods for vector controlled induction motor at variable sampling rate. to improve the steady state performance, space vector PWM (SVPWM method was used for vector controlled drives. this method requires more calculations and produces higher amplitude harmonics at around switching frequency. This results in increased harmonic distortion, electromagnetic interference and acoustic noise. Hence, this paper proposes different RPWM techniques that are able to reduce the harmonics at multiples of switching frequency. to simplify the PWM approach, the proposed approach generates the modulating signals in a simple scalar method and pulses will be generated in carrier comparison approach. Moreover, in the proposed methods the carrier frequency is varied in a limited range (±500 Hz), which simplifies the filter design. The effectiveness of the proposed methods is proved with both simulation and experimental studies.