Key Modeling Considerations for Reliable FEM-Based Demagnetization Evaluation of IPMSM Mercedes-Benz AG

Format:

Book

Conference/Event

Author/Creator:

Malner, Max, author.

Naumoski, Hristian, author.

Gretzinger, Stefan, author.

Izquierdo, Patrick, author.

Kulzer, Andre Casal, author.

Conference Name:

2026 Stuttgart International Symposium (2026-07-08 : Stuttgart, Germany)

Language:

English

Subjects (All):

Materials properties.

Finite element analysis.

Local Subjects:

Materials properties.

Finite element analysis.

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2026

Summary:

The reduction of heavy rare earth elements such as dysprosium and terbium, which are associated with high cost, geopolitical risk, and sustainability concerns, is a key objective in the electromagnetic design of interior permanent magnet synchronous machines (IPMSM) for traction applications. Since these elements are the primary contributors to magnet intrinsic coercivity, their minimization increases the risk of irreversible demagnetization of the permanent magnets. In IPMSM designs with reduced heavy rare earth content, it is therefore necessary to operate close to the demagnetization limit of the permanent magnets and accurately identify them. Consequently, a precise and reliable finite element method (FEM) based prediction of demagnetization robustness is essential for systematic and material efficient machine design. This paper investigates the key factors required for reliable assessment of demagnetization robustness in IPMSM using electromagnetic FEM. Unlike existing literature, which typically neglects the accuracy of magnet material data, evaluates only a single worst-case operating point, and relies predominantly on two-dimensional models, the presented analysis highlights the relevance of accurate magnet material characterization, multiple dynamic operating points, and three-dimensional effects. The impact of magnet material characterization is examined by comparing nominal and minimum material properties as well as open-circuit and closed-circuit measurement data, demonstrating the importance of capturing the knee point of the demagnetization curve. A sensitivity study further shows that small deviations in assumed recoil permeability can substantially affect predicted demagnetization behavior. Since demagnetization is not a binary phenomenon, different evaluation approaches are discussed, including demagnetized area thresholds and back-EMF loss. Relevant worst-case operating conditions are examined, considering maximum demagnetizing field, elevated magnet temperatures, and short circuit scenarios. Finally, the relevance of three-dimensional effects is demonstrated, showing that rotor step skew can significantly influence demagnetization behavior compared to two-dimensional models. The findings form the methodological basis for subsequent electromagnetic optimization and design studies of IPMSM with explicitly considered and enhanced demagnetization robustness

Notes:

Vendor supplied data

Access Restriction:

Restricted for use by site license