Vibration Performance of an Induction Motor with Respect to a Slot Number

Abstract

In this paper, two four-pole induction motors having 36 and 24 stator slots are analyzed in terms of vibration performance with respect to the number of rotor slots. Radial and tangential flux densities in air gap are obtained by finite element analysis, and by using the flux densities, radial force density is calculated and separated into its temporal and spatial harmonic orders through Fast Fourier Transform (FFT). The variation of radial force density regarding a slot combination is investigated, and vibration acceleration is estimated by radial force density from FFT. The relation of vibration acceleration with a rotor slot number is scrutinized in terms of temporal and/or spatial harmonic orders. Main and diagonal orders among harmonics are defined, and it is found that vibration performance deteriorates in a rotor slot number creating the 2SUPnd/SUP diagonal orders. In this paper, it is claimed that the existence of the 2SUPnd/SUP diagonal orders is determined by several simple equations, and a slot combination is easily evaluated in terms of vibration performance by the equations obtained from this research.