Finite element analysis of electromechanical devices with anisotropic materials

Finite element analysis using Galerkin's method is employed for solving two-dimensional stationary magnetic-field problems associated with nonlinear and anisotropic magnetic systems. A sequential direct iteration scheme was applied to solve the resulting nonlinear algebraic equations; the use of optimization techniques and the judicious choice of the relaxation factor assisted materially in minimizing the convergence time. Error criteria based on element reluctivity and total system magnetic energy are considered superior to flux density convergence criteria. The methods developed were applied to a permanent magnet linear actuator, used in computer disk drives. Even though the magnetic system showed flux densities exceeding 3.0 T at critical points, good agreement between computed and test values of flux density in the air gap was achieved. Fast convergence of a 360- element mesh was achieved.