Vibration of PM Brushless Machines Having a Fractional Number of Slots Per Pole.

In this paper, a method for predicting the electromagnetic vibration of permanent magnet (PM) brushless motors is presented. It calculates the electromagnetic force on individual stator teeth by the Maxwell stress method, based on two-dimensional finite-element analysis of the electromagnetic field. The resulting radial force contour is then used in an analytical shell model to predict the stator vibration. The method is validated experimentally, and is used to investigate the vibration in various PM brushless motors with different fractional slotlpole number combinations. The relationship between the slot/pole number combination and the dominant vibration frequency and mode order is also established. [ABSTRACT FROM AUTHOR]