Investigation and Experimental Verification of a Novel Spoke-Type Ferrite-Magnet Motor for Electric-Vehicle Traction Drive Applications

In order to exhibit high performance, traction drive motors that use rare-earth magnets have been mainly applied to hybrid and electric vehicles (EVs). However, the raw materials of the magnets have critical issues such as unstable supply and high cost. Thus, a variety of motors not using rare-earth materials have been intensively developed for the traction motor. Nevertheless, it has limitation in increasing the performance of such motors without the use of rare-earth magnets. Accordingly, this paper investigates the availability of a spoke-type ferrite-magnet motor (FMM) with a novel rotor configuration for EV traction motors. In particular, the proposed motor has two rotor designs, and its characteristics based on finite-element analysis are compared according to each rotor design. Furthermore, various mechanical characteristics such as thermal stability, structural safety, and acoustic noise are checked in the design stage of the spoke-type FMM. Finally, the spoke-type FMM is tested in order to verify its performance and feasibility, including vehicle installation and on-road test in LA4 city driving mode.