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This paper aims to define a minimum set of finite-element (FE) solutions to be used in the design and analysis of saturated permanent-magnet motors. The choice of the FE 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-magnetomotive-force diagram. When synchronous machines are considered, such a diagram has a regular shape, so that a huge reduction in FE 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 the variation of the flux linkage with the rotor position. At last, this paper describes a technique in which few FE solutions allow the identification not only of the average torque but also of the main torque harmonics. As a result, the torque behavior versus rotor position can be rapidly predicted

This paper presents optimal design solutions for reducing the cogging torque of permanent magnets synchronous machines. A first solution proposed in the paper consists in using closed stator slots that determines a nearly isotropic magnetic structure of the stator core, reducing the mutual attraction between permanent magnets and the slotted armature. To avoid complications in the windings manufacture technology the stator slots are closed using wedges made of soft magnetic composite materials. The second solution consists in properly choosing the combination of pole number and stator slots number that typically leads to a winding with fractional number of slots/pole/phase. The proposed measures for cogging torque reduction are analyzed by means of 2D/3D finite element models developed using the professional Flux software package. Numerical results are discussed and compared with experimental ones obtained by testing a PMSM prototype

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The paper presents a new contactless hybrid excited claw pole synchronous machine. The excitation field is produced by both NdFeB permanent magnets mounted on the rotor, and two fixed coils embedded within machine shields, and fed from a controlled DC source. A 3-D numerical model based on the Finite Element Method (FEM) that takes into account the magnetic circuit nonlinearity and movement of the armature is used to demonstrate the principle of the new excitation system. The no-load and magnetization characteristics, as well as the e.m.f. time dependence are calculated. The main operating characteristics of the manufactured machine have been determined experimentally for motor and generator regimes.Index Terms -hybrid excitation synchronous machine, finite element methods, permanent magnets.

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