A Novel Analytical Model for On-Load Performance Prediction of Delta-Type IPM Motors Based on Rotor Simplification

A simplified analytical subdomain model for determining the on-load air gap magnetic field distribution and performance prediction in delta-type interior permanent magnet (IPM) machines is presented in this work. The complex IPM rotor with two-layered rectangular magnets, iron bridges, and magnetic barriers is reconstructed into the subdomain model that only contains the equivalent spoke-type magnets. The stator with the equal-width slot is also simplified according to polar coordinates. The relative permeability of the equivalent spoke-type magnet is calculated by considering the equivalence of the stator magnetic field using the relative air gap function and the remanences of the equivalent spoke-type magnets are determined by considering the equivalence of the rotor magnetic field using the magnetic equivalent circuit method. Detailed theoretical explanations of the final analytical equations for the density distribution in the air gap and the performance based on the already determined air gap density are provided. The analytical results are validated using experiments and the finite element method in both the no-load and on-load conditions. Due to the combination of the magnetic circuit method and subdomain method, the proposed method has good universality and can be applied to more complex multilayered and multisegmented IPM motors.