A Novel Dual-Layer Asymmetric Interior Permanent Magnet Machine with High Torque Density and Low Torque Ripple

In this paper, a novel asymmetric interior permanent magnet (AIPM) rotor topology featured by dual-layer asymmetric permanent magnet (PM) arrangements combining both spoke-type and pedate-shape PMs. The AIPM rotor topology can mitigate torque ripple while achieving torque enhancement simultaneously by employing magnetic-field-shifting effect with reduced current angle between maximum PM and reluctance torque components. The proposed AIPM topology and a conventional V-shape symmetrical IPM machine are designed using the same stator design, air-gap length, rotor diameters and total PM usage. The comparison of electromagnetic performance reveals significant torque ripple reduction and torque enhancement simultaneously in the proposed AIPM machine compared with the conventional IPM machine benchmark.