Three-Dimensional Hybrid Finite Element–Boundary Element Analysis of Linear Induction Machines

A three-dimensional model of a three-phase linear induction motor (LIM) is analyzed by using hybrid finite element–boundary element (FEM-BEM) analysis. Two models with aluminum rotors are considered, one with back iron and the other without back iron. The outer boundary is chosen arbitrarily in free space to enclose the motor. The problem domain is divided into rectangular brick elements. The FEM is applied for the interior region, and the BEM is applied for the outer surface. The iron parts can be simulated either as constant permeability regions or regions with the actual magnetization B-H curve. The electromagnetic field problem is solved in terms of the magnetic vector potential. Performance parameters such as propulsion force, levitation force, and dissipated power are then obtained. A comparison of the results with the available measurements from cited references shows agreement within 4–5% for the model without back iron and 9–14% for the model with back iron. It also shows the significant impact of the hybrid FEM-BEM in comparison with the FEM.