Effects of cogging torque reduction techniques applied to surface mounted PMSMs with distributed windings

This paper investigates what effects different cogging torque reduction techniques, have on the cogging torque waveforms and air-gap flux density of surface mounted PMSMs with distributed windings and large number of slots per pole. Methods such as magnet step skew, stator teeth dummy slots and magnet pole shaping are the main scope of the paper, as they do not result in unwanted rotor unbalances. The effects of different number of magnet pole segments and different skew angles on the cogging torque waveforms are also depicted. Two dimensional Finite element analysis (FEA) is performed in order to obtain the cogging torque peak-to-peak variations and air-gap flux density distribution.