Magnetostriction Vibration and Acoustic Noise in Motor Stator Cores

This study focuses on the impact of magnetostriction on vibration and acoustic noise emitted from motor stator cores. Typically, motor vibration and acoustic noise are attributed to radial electromagnetic forces, torque ripple, and pulse-width modulation switching. However, it is important to consider the influence of magnetostriction in iron core materials with high magnetostriction. In this study, an analytical model was developed to derive the equivalent magnetostrictive force in a global cylindrical coordinate system to understand the effect of magnetostriction on motor iron cores. Three core materials with different magnetostriction characteristics were used to fabricate three individual stator cores for comparative experiments. To isolate the effect of magnetostriction, an additional toroidal winding was added to excite the stator yoke, avoiding the generation of electromagnetic forces and inducing vibration solely by magnetostriction. The magnetostrictive strain, vibration, and sound pressure level of the three stator cores were measured and compared. The results clearly indicate that magnetostriction has a significant impact on vibration and acoustic noise in motor cores, particularly in high-magnetostriction core materials.