1.2 MW, 2-6Krpm BLDC-MRM Traction Drive: Preliminary Design with Key FEM Inquiries

The BLDC-MRM is a brushless d.c. multi-phase reluctance motor with bipolar two flat tops currents in the stator with a q=1 slot/pole/phase diametrical multiphase (m>3) a.c. stator winding and a magnetically anisotropic (Ld> Lq) passive rotor. The absence of rotor windings, the not so small air-gap, the around 90° natural power angle, good torque density, simple i
_E
, i
_T
control, high fault tolerance and good d.c. link input voltage usage in the inverter make BLDC-MRM tempting for many applications, including heavy traction. The present paper aims a first attempt to introduce a rather complete analytical sizing method accompanied by key FEM validation for emf (by i
_F
) waveform, torque pulsations and realization. Thermal stress is also investigated by FEM with promising results for 1.2 MW 2/6krpm traction applications.