Analytical models for exterior-type permanent magnet synchronous motors

Advances in high energy permanent magnet materials and power electronics have widely enhanced the applications of Permanent Magnet (P.M.) synchronous motors in variable speed drives and robotic systems. Determination of equivalent circuit parameters is of critical importance for the performance prodiction of such motors. The purpose of this paper is to develop magnetic and its dual electric equivalent circuit model of P.M. synchronous motors with surface mounted radial and circumferentially oriented NdBFemagnets in the rotor assembly. Simplified analytical expressions for both the direct and quadrature axis parameters are provided taking into account the modified Carter´s coefficient and saturation effects. Experimental results are presented to verify the analytical models. There exits a reasonably close agreement between the measured and predicted reactance parameter values.