Cogging torque optimization of a four-pole PM machine

This paper presents a finite element based optimization study of a four-pole permanent magnets machine. The purpose of the analysis is to find a constructive solution characterized by a cogging torque less than 1% of the rated torque of the reference machine and reduced e.m.f. harmonics. The elements that are modified during the optimization process are the cross-section geometrical parameters of the permanent magnets and of the rotor core by keeping unchanged the magnets volume and stator geometry. Several constructive measures were studied, the best one being deeper analyzed. The numerical analysis is based on 2D magneto-static and transient magnetic type finite element models of the machine. Some of the numerical results are validated by experimental measurements.