Performance Improvement of Wound Field Synchronous Motor for EV Propulsion Applying Grain-Oriented Electrical Steel

Abstract

This study investigates the performance enhancement of wound field synchronous motors (WFSMs) through a design method that incorporates grain-oriented electrical steel (GOES). Cross-magnetization, resulting from the overlapping fluxes of the d- and q-axes, occurs within the rotor of the WFSM. Consequently, rotor design must enable optimal utilization of cross-magnetization to enhance electromagnetic performance. This study proposes an approach that uses the magnetic properties aligned with the easy axis of GOES, aiming to improve cross-magnetization utilization and reduce copper loss. Electromagnetic torque improvements are demonstrated by analyzing the magnetic flux path in comparison to models using non-oriented electrical steel (NOES). Furthermore, the role of cross-magnetization in performance enhancement is examined through a detailed analysis of the easy axis of GOES. Finally, the superiority of GOES is established through optimal rotor designs based on the type of electrical steel applied.