A Novel Asymmetric-Magnetic-Pole Interior PM Machine With Magnet-Axis-Shifting Effect

This article proposes a novel asymmetric-magnetic-pole interior permanent magnet (AMP-IPM) machine, which is geometrically characterized by a combination of dual-layer reluctance and flat-type PM rotor structures. The design concept of “asymmetric-magnetic-pole” is introduced to achieve a magnet-axis-shifting effect, namely, the magnet
d
-axis is shifted to make PM and reluctance torque components approximately maximize at similar current angles. Consequently, the resultant torque can be further improved without increasing magnet usage. The machine topology is first introduced. The electromagnetic characteristics of the proposed AMP-IPM machine are then investigated and compared with those of the benchmark conventional IPM machine with symmetrical magnetic poles, with similar sizing and PM usage. Finally, an AMP-IPM machine prototype is manufactured and tested, which confirms the feasibility of the proposed AMP design for the torque performance improvement.