A Novel Asymmetric Rotor Interior PM Machine with Hybrid-layer PMs

This paper proposes a novel asymmetric interior permanent magnet (AIPM) rotor topology featured by the hybrid-layer permanent magnets (PMs) placed in the trident cavity in each pole, namely, one part of the rotor PM topology is one layer while the other part has two layers. This asymmetric rotor topology utilizes the magnetic-field-shifting (MFS) effect for torque enhancement by reducing the current angle difference between maximum PM and reluctance torque components, thereby effectively increasing the maximum resultant torque. The proposed AIPM topology and a conventional V-shape interior permanent magnet (IPM) machine are designed with the same stator, rotor diameters and PM usage for comparison. The influences of key rotor geometric parameters on maximum torque and open-circuit performance are investigated and optimal machine designs are obtained. The electromagnetic performances of the proposed AIPM and the conventional IPM are compared, which confirms the significant torque enhancement and torque ripple reduction of the proposed AIPM and reveals that the increase of torque is mainly achieved by MFS effect.