Magnetostriction Effect on Vibration and Acoustic Noise in Switched Reluctance Motor

The contribution of magnetostriction to vibration and acoustic noise in switched reluctance motors is investigated through finite element analysis and experiment on two motors. One motor was constructed using the 6.5% high-silicon steel 10JNEX900 with a low magnetostriction (0.3 ppm at 1 T), whereas the other motor was made of the amorphous iron 2605SA1 with a high magnetostriction (11.0 ppm at 1 T). Finite element analyses were performed on two cases: a static excitation and a typical motor operation. In the case of the static excitation, the magnetostrictive deformation is not only significant but also counteracts the deformation caused by the electromagnetic force, reducing the total deformation. In the case of the typical motor operation, a similar counteraction effect due to magnetostriction was confirmed in mode-0 (breathing mode) vibrations in the amorphous iron motor. This counteraction effect in both mode-0 vibration and acoustic noise was also verified in the experiment. Such experimental results, which highlight the significance of magnetostriction for motor vibration and acoustic noise, have not been reported in the existing literature. The analytical and experimental findings of this study suggest that magnetostriction should be considered when assessing the vibration and acoustic noise of motors made of high-magnetostriction core materials.