Speed Variations in Cage Induction Motors Under Sinusoidal Voltage Modulation

A specific case of voltage fluctuations is sinusoidal voltage modulation, which is a superposition of the fundamental voltage component and the subharmonic and interharmonic components – that is components of frequency less than the fundamental one or not being an integer multiple of it. Depending on the phase angles of the subharmonic and interharmonic components, various cases of voltage modulation can be distinguished, like amplitude, phase and intermediate modulations. This paper deals with the effect of phase angles of the subharmonic and interharmonic components on speed variation. The results of FEM computations are presented for a cage induction motor with a rated power of 3 kW.