Analysis and design of a six-phase fault-tolerant PM machine used for EVs

Fault-tolerant permanent-magnet machine (FTPM) is an ideal choice for the drive motor in electric vehicle(EV) applications because of its advantages in control performance, efficiency, torque density and the capacity of operating under the failure of windings and converter. This paper designs a six-phase FTPM used for EV. To meet the requirements of physical and magnetic separation of the various phases, single-layer fractional-slot concentrated windings (FSCW) were adopted. A slot and pole combination was proposed to reduce the eddy loss in permanent magnet resulting from the use of FSCW, and the iron loss declined with the decrease of the number of poles. By analyzing the torque ripple caused by concentrated windings and the inductance matrix in dq0-coordinate in the case of decoupling of various phases, the FTPM's rotor type was confirmed. Finally, the prototype of a 6-phase FTPM was proposed and some performance parameters were listed.