Translator Eccentricity Analysis in Tubular Linear Machines Using Quasi-3-D Finite Element Method Modeling

This article attempts to present a quasi-3-D finite element method (FEM) technique for modeling and analyzing tubular linear permanent magnet machines (TLPMs) with translator eccentricity. Normal tubular linear machines can be modeled effectively using 2-D axisymmetric models, but, with the introduction of the eccentricity factor into the geometry, the axis symmetry is no longer valid, and hence, 3-D modeling techniques become the only way for studying the machine. However, sometimes, 3-D modeling can become time-consuming and requires a huge amount of resources especially for non-linear problems, so the interest in modeling techniques that can represent the problem at hand with less computation time and relatively accurate results is high. A quasi-3-D technique was specifically developed to be able to represent the eccentricity in TLPMs. The FEM was used for modeling. The eccentricity analysis has been carried on two different TLPM structures using the proposed quasi-3-D, and the results from the quasi-3-D model were compared to those obtained using the 3-D FEM model. Both the open-circuit and on-load operating conditions were studied with the magnetic saturation taken into account. The behavior and the accuracy of the proposed model varied between the two studied structures and for the different operating conditions, and with very low computation time and cost, the results obtained from the quasi-3-D model were satisfactory in general except for certain cases.