Investigation of Novel Interior PM Machine with Asymmetric Magnet Distributions for EV Application

This paper proposes a novel magnet-axis-shifting IPM (MAS-IPM) machine with asymmetric magnet distributions for traction applications. With asymmetrical PM distribution and adjustment of air space barriers width of the rotor, MAS effect can be achieved to make the magnet and reluctance torque components reach their peaks at closer current angles. The operating principle and the topology derivation of the proposed MAS-IPM are introduced first, and the open-circuit field distribution is utilized to reveal the MAS effect clearly. In addition, the design optimization is carried out to obtain the optimal torque performance of the proposed machine. The electromagnetic characteristics of the proposed MAS-IPM machine are investigated and compared with those of the benchmark Toyota Prius 2010 IPM machine. The analysis results suggest that the proposed MAS-IPM machine can provide higher torque density and higher efficiency using same volume of PMs, which makes the novel machines promising for electric vehicle applications.