Investigation of Forces and Secondary Losses in Linear Induction Motor With the Solid and Laminated Back Iron Secondary for Metro

Abstract

In this paper, two main kinds of the secondary, i.e., the solid and laminated back iron secondary, are applied in linear metro, as well as electromagnetic forces and secondary losses of the single-sided linear induction motor (SLIM) with different secondary are calculated by the finite-element method (FEM). First, in solving region, the fundamental equations of the magnetic field with eddy currents in the secondary are deduced, and specific boundary conditions for each part of SLIMs are given. Equations of the secondary loss and efficiency are presented. Second, 120-kW SLIMs with two types of the secondary for metro are calculated by the three-dimensional FEM, respectively. The efficiency and secondary loss are analyzed for different numbers of the lamination in the secondary back iron. The optimal number of the back iron lamination is then obtained. Third, considering the influence of the end and edge effect, the air gap flux density with different secondaries is calculated. Then, the thrust and vertical force are analyzed for SLIMs with two kinds of the secondary. Finally, numerical results of the efficiency, thrust, and vertical force, which are obtained from different secondaries, are experimentally validated by measurement on the test rig of the SLIM.