Impact of Partially Demagnetized Permanent Magnets on Operating Range of an Interior Permanent Magnet Synchronous Machine

The drive towards more sustainable technologies has accelerated the development of alternatives to heavy rare-earth (HRE) permanent magnet (PM) materials in electric machines, particularly Interior Permanent Magnet Synchronous Machines (IPMSMs). As a result, HRE-free PM materials have emerged as potential substitutes, although they are significantly more prone to demagnetization, especially at elevated temperatures and high external demagnetization fields. This research proposes a parametrized model for the PM geometry in the rotor of an IPMSM, which allows to effectively account for the demagnetized portion of the PM and its impact on the operating region of the IPMSM. The proposed models have been applied in 2D Finite Element Method analysis, where two HRE-free PM materials and one HRE PM material were compared. Through the performed analysis, we aimed to demonstrate the impact of the partially demagnetized PM on the operating range and compare the sensitivity of selected HRE and HRE-free PM materials to demagnetization.