Design Optimization on Secondary and Performance Improvement of Long Primary Double-Sided Linear Induction Motor

Induced eddy current in the secondary conductor plate of long primary double-sided linear induction motor (LPDSLIM) is asymmetrically distributed since the dynamic longitudinal end effect caused by open-end structure in secondary. This is one of the most influential reasons of the thrust fluctuation. In this paper, a thrust fluctuation reduction method based on the secondary of a longitudinal skew end has been proposed. The thrust fluctuation reduced effect of three different proposed secondary structures, i.e. parallelogram shape, swallow-tail shape and shuttle shape has been firstly comparatively analyzed based on the 3D finite element method (FEM). Then the influence of end skew distance on the thrust performance of LPDSLIM with shuttle structure secondary has also been studied. It has been found that shuttle type secondary can effectively reduce thrust fluctuation without sacrifice of average thrust. This effect is independent on motor slip frequency.