MODELING AND COMPUTATION OF NONLINEAR MAGNETIC-FIELDS IN LINEAR STEP MOTORS BY FINITE-ELEMENT METHOD

This paper describes the implementation of finite element method (FEM) for modelling and computation of magnetic fields in cylindrical passi ve armature linear step motors (LSM) used in control rod drives of nuc lear reactors. The 2D nonlinear axisymmetric magnetic field is simulat ed using dedicated finite element (FE) package developed for CAD and p erformance evaluation of such motors. Various aspects of FE modelling in complex geometry of LSM are discussed. Results are presented in ter ms of. field plots and electromagnetic force versus armature position curves (static characteristics) of the industrial prototype of a LSM. Some of the results are compared with experimental data which show sat isfactory agreement.