Dynamic demagnetization computation of permanent magnet motors using finite element method with normal magnetization curves

A time-stepping finite element method (FEM) to simulate the transient operations of permanent magnet (PM) motors is presented. It uses only the normal magnetization curves to address the effects of irreversible demagnetization of PM materials. An effective algorithm to implement the methodology with nonlinear iteration is presented. A formulation of Newton-Raphson method using the true Jacobian matrix which is applicable to any type of elements and any order of elements with anisotropy materials is derived. A matrix method is introduced to express space vectors and the FEM formulation can be conveniently deduced.