Analytical Model for Sizing the Magnets of Permanent Magnet Synchronous Machines

Abstract

The paper presents a procedure for determining dimensions of magnets that confirm the required characteristics of a PMSM (permanent magnet synchronous motors). The magnet sizes influence on the saliency of the motor and consequently on its parameters and characteristics. An analytical model that accounts the salience, the stator resistance and saturation has been developed. The model uses FEA (finite element analysis) to obtain the stator windings flux linkage, direct-axis and quadrature-axis inductances and phase shift between the quantities. The distribution of the magnetic field produced by the permanent magnets and the magnetic field at operation with rated load has been obtained using this model. An iterative procedure changes the dimensions of the magnets at each step and performs analysis of the model until an operating point with required characteristics is achieved.