MMF Harmonics Effect on the Embedded FE-Analytical Computation of PM Motors

This paper aims to define a minimum set of finite element solutions to be used in the design and analysis of saturated permanent-magnet motors. The choice of the finite element solutions belonging to this set is strictly associated with the classical d - q axis theory and it is described in terms of key points on the Flux-MMF diagram. When synchronous machine are considered, such a diagram has a regular shape, so that a huge reduction in finite element field solutions is possible with no loss of accuracy. It is also shown that the torque computed by using the d - q axis theory is almost independent of variation of the flux linkage with the rotor position. At last, the paper describes a technique in which few finite element solutions allow the identification not only of the average torque, but also the main torque harmonics. As a results, the torque behavior versus rotor position can be rapidly predicted.