Analytical Prediction of Partial Demagnetization in Interior Permanent Magnet Synchronous Motor Using Magnetic Equivalent Circuit Modeling

In Interior Permanent Magnet Synchronous Motor (IPMSM) for railway traction applications, irreversible demagnetization of permanent magnets can lead to severe degradation in motor performance and even system failure. The irreversible demagnetization can be induced by high temperature, opposing magnetic fields, or mechanical stress. While Finite Element Analysis (FEA) is highly accurate in predicting the irreversible demagnetization, it is computationally expensive and inefficient for the early design stage, where repeated geometric changes and parametric studies are often required. In this study, a Magnetic Equivalent Circuit (MEC)-based approach is proposed to efficiently assess the risk of partial demagnetization in the Permanent Magnets (PMs). The method enables localized analysis by dividing the magnet into structurally weak subregions, such as ribs and bridges, and evaluating whether demagnetization is likely to occur in each area. The proposed technique offers a fast and practical solution to identify demagnetization-prone regions in the initial design phase of railway IPMSM.