Fault-tolerant performance comparisons between external and internal rotor PMa-SynRMs

This paper presents a detailed comparison between fault-tolerant five-phase external and internal rotor permanent magnet assisted synchronous reluctance motors (PMa-SynRMs). Critical applications such as electric vehicles and more electric aircraft demand high power density and fault-tolerant capability in their traction motor designs. Five-phase external rotor motors are proposed to generate higher torque density compared to conventional internal rotor motors of same size. However, under fault conditions such as single-phase, two-phase adjacent, and two-phase non-adjacent faults, the fault-tolerant capability of such high torque density motors needs to be investigated. Furthermore, severe torque pulsations under such faults have to be restrained in traction motors. In this study, five-phase external rotor PMa-SynRMs are optimally designed to generate higher torque density with lower torque ripple and better fault tolerant capability when compared to a same size five-phase internal rotor PMa-SynRM. Finite element simulations are carried out to compare the performance of external rotor PMa-SynRMs under single-phase, two-phase adjacent and two-phase non-adjacent faults. Experiments under no-load conditions and load are carried out to validate the simulations.