Investigating the Role of Non-Oriented Electrical Steels Magnetic Polarisation and Mechanical Strength In Boosting Traction Electric Motor Performance

Selecting the optimal fully-processed non-oriented electrical steel (NOES) grade is vital for achieving the best performance of traction motors in electric vehicles. Besides the minimal magnetic losses, it is important to consider high mechanical strength and enhanced magnetic polarization during the NOES grade selection process. This study aims to investigate the compromise between the high magnetic polarization and the high mechanical strength properties of NOES grades, and their impact on the energy savings as well as torque density enhancement in electric traction motors. To accomplish this, two motor topologies were analyzed using finite element numerical simulations: an interior permanent magnet synchronous motor (IPMSM) and a rare-earth-free wound-rotor synchronous motor (WRSM). Two ArcelorMittal NOES grades families are investigated, iCARe® Torque and iCARe® 420 Save, and compared to iCARe® Save grade as a reference case. The analysis findings indicate a noteworthy correlation between the increased magnetic polarization of the NOES and the improved motor torque density in WRSMs, and a clear relationship between a higher mechanical strength property and a higher torque density in IPMSM thanks to the optimized rotor design enabled by the elevated mechanical yield strength. Consequently, also the energy saving of the considered traction motors is improved with such higher-performance NOES grades.