Study of the Influence of the Width and the Pair Shift Of Permanent Magnets on the Torque of an Electric Motor

Abstract

The article discusses ways to reduce the torque ripple in a permanent magnet motor. With the use of the FEMM program, computational studies were carried out to determine the effect of the width of the magnets and the magnitude of their pairwise angular displacement on ripple in the nominal mode and no-load. The studies were carried out for a sixteen-pole motor with permanent magnets placed on the rotor surface, with a distributed winding on the stator and the number of slots per pole and phase equal to 1. The calculations were performed for a rotor with a magnet width in the range of 0.6 - 0.85 p.u. rated torque. It is noted that in the idle mode, the change in the width of the magnets in the specified range and a decrease in the angle of their pairwise shift makes it possible to reduce the pulsations to a level of 1.3 % of the nominal torque. In the nominal mode, the variation in the width of the magnets and the pairwise angular displacement allows the torque ripple to be reduced to 4.7 %.