High-pole-number Halbach permanent magnet synchronous motors (PMSMs) exhibit excellent torque density and low harmonic distortion but suffer from severe cogging torque, which limits smooth operation and acoustic performance. This paper presents a comprehensive comparative study of three cogging torque reduction methods—magnet shifting, magnet shaping, and rotor step skewing—applied to a high-pole-number Halbach PMSMs, with particular emphasis on their effectiveness under manufacturing tolerances. Finite element simulations are conducted to evaluate each method’s impact on cogging torque, no-load back electromotive force (No-load Back-EMF) fundamental amplitude, and total harmonic distortion (THD). A tolerance sensitivity analysis is performed using the One-Factor-at-a-Time (OFTA) approach, considering key geometric deviations including magnet, stator slot, and static eccentricity. Among the three methods, magnet shifting demonstrates the most favorable balance between torque suppression and robustness, achieving over 95% cogging torque reduction with minimal degradation in No-load Back-EMF amplitude performance. Experimental validation on a 28-pole-pair, 168-slot prototype confirms the simulation accuracy, showing a cogging torque reduction from 40.8 to 1.85 N m, and validating the method’s practical feasibility.
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