Effects of an Optimized Adhesive Distribution on Stresses and Strains in the Rotor and Magnets of a Surface Permanent-Magnet Synchronous Electric Motor

It is well-established in the literature that surface-mounted permanent-magnet synchronous motors (SPMSMs) have a high torque density due to an elevated interaction between magnetic flux and windings. For this reason, SPMSMs are extensively studied. This paper investigated the mechanical interactions and strains that develop in the main components of the rotor of an SPMSM, with particular focus on the behavior of the adhesive layer used for magnet bonding. An iterative methodology was proposed to improve both the amount and distribution of the adhesive to reduce stress, from 182 to 9 MPa, and deformation, from 0.182 to 0.008 mm, in critical components such as permanent magnets (PMs). SPMSM rotors are particularly sensitive to centrifugal forces, which tend to expel the PMs radially toward the stator. This effect leads to deformations in the rotor, PMs, and adhesive layer, resulting in a reduction of 16% from the original airgap without adhesive and in the generation of stresses that must remain within acceptable limits, stresses which go beyond 170 MPa in the layout without adhesive. Several fastening configurations of the PMs were analyzed, each incorporating a mechanical retaining element, primarily for safety purposes, combined with different adhesive distribution strategies.