Harmonic torques in three-phase induction motors supplied by nonsinusoidal voltages

Abstract

Low-short-circuit-capacity electric systems may present considerable distortion in the voltage waveform when supplying nonlinear loads. Three-phase induction motors when connected to such a system may suffer additional requirements during start-up as overheating in the rotor bars due to the skin effect, and mechanical vibrations in the shaft due to harmonic torques. This work presents an approach to analyze the behavior of the harmonic torques produced by three-phase induction motors when supplied by nonsinusoidal voltage, taking into account the skin-effect in the rotor bars and the saturation of the stator leakage reactance during start-up. It is important to notice that the analysis and the derived equations are based on ordinary data available in the manufacturer's catalogue.