3D FEM characterization of a switched reluctance motor from direct experimental determination of the material magnetization curve

Analytical characterization of a switched reluctance motor (SRM) by means of magnetic circuit theory can be a tedious task. Specific software based on the finite elements method (FEM) for solving non linear magneto-static problems has proved very useful for this characterization. However, to solve the Maxwell equations it is necessary first to know the magnetization curve of the material used for building the motor, which may not be available in the program materials library. A simple and low cost method for a direct determination of the first magnetization curve of a magnetic material is presented in this communication. Through one single test of short duration, (which allows to reach high values of the magnetic field strength while keeping the material temperature practically constant), we obtain a B-H curve that fits correctly to the samples obtained by a traditional method requiring the identification of multiple hysteresis loops. This B-H curve has been included in a FEM program to determine the flux linkage-current-position characteristic of a SRM prototype. The results again fit those obtained experimentally, confirming the validity of the proposed method.