Electromagnetic Performance Analysis of Consequent-Pole PM Machine With Asymmetric Magnetic Pole

Abstract

The permanent magnet (PM) machine with consequent-pole (CP) rotor can improve the PM utilization ratio. However, the replacement of the PMs with the same polarity by the salient iron core deteriorate the electromagnetic performance of the machine, including higher torque ripple and unipolar leakage flux. Therefore, a CP PM machine with asymmetric magnetic pole (AMP) structure is proposed, through which the smaller torque ripple and unipolar leakage flux can be obtained, without deteriorating the torque characteristics compared with the traditional CP PM machine. Furthermore, the electromagnetic performance and the unipolar end leakage flux of the AMP and traditional CP PM machines are investigated by the finite-element method (FEM). It is demonstrated that AMP structure can reduce the cogging torque and torque ripple; furthermore, the unipolar leakage flux can be suppressed effectively. Finally, the prototype with AMP and CP PM rotor are fabricated and tested to verify the theoretical and FE analysis.