Magnetic shielding for coreless linear permanent magnet motors

This paper concerns the local reduction of the magnetic flux density by means of magnetic shielding. Using a spatial frequency description, a 2-D semi-analytical periodic model is obtained for a coreless single-sided linear permanent magnet motor. The magnetic shield is included in the modeling using mode-matching. The obtained magnetic flux density is compared to a finite element model and is verified with measurements. The results show a reasonable agreement between the semi-analytical model and the measurements. Some large deviations occur due to the modeling assumption that the shield has a linear permeability, while the used shields are saturated. However, the semi-analytical modeling method is accurate enough for design purposes and initial calculations, especially when being aware of the possible saturation of the shield.