Design aspects of a 50hp 6-pole synchronous reluctance motor for electrified powertrain applications

In this paper, design aspects of a 6-pole synchronous reluctance traction motor are presented for improving the machine performance in electrified powertrain applications. An increase in the number of poles at the same current rating amplifies the output torque and reduces the torque pulsations. Moreover, in this machine, anisotropic structure of the rotor eliminates use of cage, windings, and magnets results in a lower cost. Combination of the aforementioned qualifies this machine as an important candidate for the traction motors in the near future. The rigid structure of rotor enables the machine to operate at high speed that leads to compactness and higher torque density. To achieve a proper design, the machine needs to meet a desired torque envelope in different modes of operation i.e., start-up, acceleration, and cruising that highlights the cross sectional effects of the magnetic and mechanical performances. In this work, the magnetic and mechanical performance analyses of a 6-pole machine with respect to the pole numbers, rotor multi-layer structure, rotor mechanical robustness, desired torque envelope, and the maximum operating speed are discussed and compared with a well-known 4-pole geometry in order to address the proposed machine perforce improvements.