Force calculation in axisymmetric induction devices using a hybrid FEM-BEM technique

A hybrid finite element-boundary element coupling method using time stepping is presented for the computation of forces in axisymmetry. The bounded regions containing excitation, eddy currents, and magnetic areas are analyzed with finite elements, while the exterior linear region is treated with boundary elements. The force on a movable part is calculated from the values of the magnetic field with the help of the Maxwell stress tensor. The hybrid model is used to determine the axial force exerted on the rotor of a tubular linear induction motor. It provides an accurate analysis of the field distribution in the motor and gives precise values of the force by taking the end effects into account