An In-Phase Unit Slot-Opening Shift Method for Cogging Torque Reduction in Interior Permanent Magnet Machine

The cogging torque reduction methods in permanent magnet (PM) machines are more or less FEA trial and error-based cause undesirable side effects, such as distorted back EMF, new harmonic components, structure asymmetry. A slot-opening grouping method can address these issues. However, it needs to model all slots design validation during practical optimization iterations, also leads back-EMF reduction. In this paper, a strategy, termed in-phase unit (IPU), is introduced, together with the angle-shift method. slot openings same distribution pattern grouped into an IPU, peaks of within IPU now be interleaved. Thereby, major components cancelled out, instead being summed up. principle, shift angle computation, selection order cancel analyzed detail. By comparison, proposed not only simplifies iterations by modeling one FEA, but compensates for constant effectiveness validated two typical interior PM machine cases.