Prediction of Post-Demagnetization Electromagnetic Performance for SPMSM Considering Rotor Eccentricity

Rotor eccentricity is usually unavoidable due to manufacturing tolerance, and a certain degree of irreversible demagnetization (ID) is allowed to increase the power density, hence it is worthwhile to study the electromagnetic performance under both faults. To this end, the electromagnetic performance of surface-mounted permanent magnet (PM) synchronous motor with static eccentricity (SE) and dynamic eccentricity (DE) after local ID (LID) is investigated in this article. First, a generalized LID calculation method based on the PM subdivision model is proposed to realize the quick and exact localization and computation of LID. Considering the core saturation and nonlinearity of demagnetization curve, an equivalent transformation model is established to simulate rotor eccentricity effect. Combined with the improved subdomain (SD) method, a magnetic field analytical model considering rotor eccentricity and LID is established to realize the rapid prediction of key electromagnetic performances including air-gap flux density, electromagnetic force, unbalanced magnetic force (UMF), back electromotive force (BEMF), cogging torque, and electromagnetic torque. On this basis, the effect of eccentricity on LID and both faults on electromagnetic performances are revealed. The effectiveness of the analytical method (AM) is verified by finite element analysis and experiment. The short simulation time of the model provides a fast means for motor design and fault-tolerant optimization.