Design of Experiments Analysis of Manufacturing Variations on Performance of Halbach Array Slotless Motors

Outer rotor Permanent Magnet Synchronous Motors (PMSMs) with Halbach array offer higher torque density, lower losses, and lower rotor mass compared to the conventional surface-mounted magnet configurations. The manufacturing and assembly of Halbach arrays in mass-produced machines are subject to variations in dimensions, magnet strength, and orientation due to the manufacturing tolerances, which affect the back-EMF, torque ripple, and torque output of the machines. Halbach array based designs are expected to be more susceptible to manufacturing variations due to the high number of magnet pieces. This research analyzes the effect of manufacturing tolerances and variations of the magnets on the performance of slotless Halbach PMSMs using FEA analysis. The study introduced a fractional factorial analysis of the torque profile in the first step of the two-step Design of Experiment to manage the large number of variables with manufacturing variations.