Design and analysis of consequent pole permanent magnet synchronous motor with low torque ripple

Permanent magnet (PM) motor with consequent pole (CP) rotor can improve the PM utilisation ratio. However, one group of PMs with the same polarity is replaced by iron core, which deteriorates the electromagnetic performances of the motor, including asymmetric air-gap magnetic field and larger torque ripple. To solve this problem, this study analyses the relationship between the torque ripple and the stator-rotor magnetomotive force (MMF) harmonics, determines the harmonic orders causing the torque ripple of the CP PM (CPPM) motor, and proposes an unequal-turn four-layer winding structure which can eliminate the determining harmonics in the stator MMF. Furthermore, the electromagnetic performances of the CPPM motors with the proposed winding structure and traditional CPPM motors are investigated by the finite-element analysis. It is verified that the CPPM motor with the proposed structure has better motor performances.