On the Behavior of Induction Motors in Presence of Voltage Amplitude Modulations

– The voltage fluctuations of the electrical power supply and their effects on both industrial and domestic apparatuses are today a central topic of discussion. The aim of this paper is the evaluation of the effects of the low-frequency voltage amplitude modulation on induction motors, with both numerical and experimental analysis. For the numerical analysis different kinds of modulations have been considered, as suggested by the international committees; an experimental analysis has been applied to a three phase, 7.5 kW induction motor with the adoption of an ad hoc system for the EMC lowfrequency immunity testing, with the adoption of rectangular amplitude modulations. The numerical and the experimental results show that a few percent amplitude modulations can involve a critical behavior in terms of torque. As for the light flicker effect measurement, a statistical approach can be adopted for the evaluation of the torque ripple, and a simplified relation can be used to relate the torque ripple to the measurement of the instantaneous voltage waveforms, without direct mechanical measurements. Key-Words: Power quality, voltage fluctuation, induction motors, electrical machines testing.