Influence of the Ladder-Slit Secondary on Reducing the Edge Effect and Transverse Forces in the Linear Induction Motor

Electromagnetic characteristics of single-sided linear induction motors (SLIMs) will be changed when the primary is displaced sideways from the symmetrical position in the metro. The transverse force will be produced, and edge effect will increase. In order to reduce the influence of the transverse force on the stability of the vehicle guidance system, the construction of the ladder-slit secondary, which consists of the slit aluminum and solid back-iron plates, is proposed and analyzed. A 3-D finite-element model (FEM) of the linear induction motor with the ladder-slit secondary is developed. With the different transverse displacements, the air-gap flux density, eddy currents, and forces are calculated and compared with the linear induction motor with the flat-solid secondary. It shows that the ladder-slit secondary can reduce the transverse force and edge effect, as well as is a good method to achieve the transversal stabilization of the rail vehicle.