Heavy Rare Earth Free High Power Density Traction Machine for Electric Vehicles

A compact, heavy rare earth free permanent magnet synchronous machine with a volumetric power density of 50kW/liter is designed for electric traction applications. This is facilitated by innovations in the stator winding topology, magnet arrangement, and cooling technique. A 24-slot/10-pole dual three-phase asymmetric winding layout is adopted to improve power density, reduce harmonic losses, and improve fault tolerant capabilities. Furthermore, a novel segmented V-type magnet arrangement is proposed to address the demagnetization issues of the heavy rare earth free magnets under extreme temperatures and negative electromagnetic fields. An extensive finite element analysis has been conducted and results are presented to show the electromagnetic and demagnetization performance as well as the thermal capabilities and structural integrity of the proposed design.