Optimal Design of a Novel V-Type Interior Permanent Magnet Motor with Assisted Barriers for the Improvement of Torque Characteristics

Abstract

This paper performs a study on the optimal design of V-type interior permanent magnet motors (VIPMMs), in which the rotor is equipped with assisted barriers for the improvement of average torque and torque ripple. The approach differs from the conventional interior permanent magnet motors, in which the reluctance torque due to saliency reaches a maximum value at a current phase angle located 45 electrical degrees with respect to the maximum value obtained from the magnetic torque produced by the rotor magnets. The adoption of assisted barriers is employed to improve the torque production by creating rotor asymmetry to allow the reluctance torque and the magnetic torque reach a maximum value near or at the same current phase angle. To evaluate the contribution, the frozen permeability method is utilized to segregate the torque into its reluctance and magnetic torque components. First, an iterative optimization is performed on a concept design of a 6/4 VIPMM for demonstrating the design principle based on finite element method. Then, the VIPMM is further optimized by algorithms, such as the kriging method and genetic algorithm for improving the torque characteristics and efficiency. As a result, the optimal VIPMM with assisted barriers shows the substantially improved performance compared with a conventional design.