Secondary Back-Iron Saturation Effects on Thrust and Normal Force of Single-Sided Linear Induction Motor

The secondary back-iron plays important role in performance of single-sided linear induction motors (SLIMs). On one hand, it provides a return path for the primary flux; on the other hand, it is employed as a mechanical support for the secondary sheet. The conductivity of the iron used in the back-iron as well as its magnetic permeability influence the outputs of the machine, while the magnetic permeability itself is affected by the input frequency and secondary sheet thickness. In this paper, considering all phenomena involved in the SLIM, the output thrust is analytically derived. The normal force is also calculated by using Maxwell equations. Then, the effects of the input frequency and the secondary sheet thickness on the SLIM forces are analyzed. The motor is simulated using 2D finite element method. Comparing the finite element results with those obtained by analytical analysis confirms the analytical equations derived for the output thrust and the normal force.