Robust Design Method for Surface-Mounted Permanent Magnet Motor with Two-slot Pitches Winding Considering Eccentricity

Eccentricity is a frequent problem caused by uncertainty in the manufacturing process. Since eccentricity makes that the air gap is not uniform, torque ripple can increase. Using two-slot pitches winding can decrease the influence of eccentricity with high winding factor. This paper reports a step-by-step robust design method for eccentricity by applying two-slot pitches winding. Before we start, the advantages of two-slot pitches considering eccentricity is analyzed. Then, the eccentricity robust design method is reported in 4 steps. First, an optimal slot configuration with two-slot pitches winding is searched to improve motor characteristics considering eccentricity. Second, general optimization at uneccentric state is performed. Third, design variables which are sensitive to back electromotive force (EMF) is selected because the variation of each phase back EMF is affected to eccentricity. Finally, optimization for the robust design is conducted by a kriging surrogate model. As a verification about the proposed robust design, the result of comparison between the uneccentric model and the eccentric model is shown. For evaluating characteristics of the motor, the finite element analysis is used considering static eccentricity.