Estimation of eddy-current loss in permanent magnets of electric motors using network-field coupled multislice time-stepping finite-element method

The eddy-current loss in permanent magnets should be carefully considered in rare-earth magnet electric motors running at high rotor speeds. In this paper, a comprehensive approach to estimate the eddy-current loss in permanent magnets of electric motors is presented. The motor is modeled by a two-dimensional (2-D) multislice time-stepping finite-element method. The permanent magnets are represented by a network and its equations are solved simultaneously with finite-element equations. A special technique dealing with the multislices of the permanent magnets in the solution domain is put forward. The major merit of the proposed method is that the estimation of the eddy-current loss which is basically a three-dimensional problem can be tackled by a 2-D method resulting in significant reduction in computing time.