A Novel Spoke-type IPM Motor with Asymmetrical Rotor Structure for Torque Characteristics Improvement

Abstract

This paper proposes a novel rotor strategy for the spoke-type IPM machine (STIPMM) with four surface-mounted ferrite magnets to increase torque density and decrease torque ripple. An asymmetrical rotor structure concept is used during the design process to increase the efficiency of the two torque compositions of the STIPMM, the reluctance torque and the magnetic torque. In this design, the torque is improved by ensuring that the maximum value points of the magnetic torque and the reluctance torque are closer to each other. In order to excavate the greatest potentiality of the proposed model, the Kriging method and genetic algorithm are used to obtain the optimized model. To verify the analysis result, the frozen permeability method (FPM) is employed to provide feasible insights into the separation of the torque components based on a 2-D finite element method (FEM). To highlight the superiority of the proposed model, a conventional STIPMM with symmetrical rotor structure is adopted for comparison under the same magnet amounts, machine size and operating conditions.