Extraction of dynamic low order models for multiwinding magnetic devices based on finite element analysis

It has been shown that model order reduction (MOR) methods can be applied to extract low-order dynamic models of magnetic devices from a high-order, finite element method (FEM) based model. The FEM-MOR technique provides a pure mathematical method without introducing any heuristic assumption in modeling magnetic devices, and the technique results in easy-to-simulate, physics-based models. Three Krylov subspace-based nonlinear MOR methods-the piecewise-linear steady state (PWL-SS), direct piecewise-linear (DPWL), and trajectory piecewise-linear (TPWL)-have been presented and applied to an example inductor model including saturation and hysteresis. Among three of them, the PWL-SS method has been proved to be the most effective and accurate. However, it was not shown effective yet for multiwinding cases since the one-to-one relationship between the linearized systems and the values of the winding current in single-winding cases is not valid any more. This paper extends the FEM-MOR technique to a multiwinding magnetic device, a two-winding transformer.