Algorithm of Linear Induction Motor Control for Low Normal Force of Magnetic Levitation Train Propulsion System

This paper presents the analyses and experimental results of a single-sided linear induction motor (SLIM) thrust and normal force for the propulsion of semi-high-speed magnetic levitation (maglev) trains. These trains are composed of a levitation system that uses electromagnetic suspension and a propulsion system that uses SLIMs. The propulsion system of maglev trains using SLIMs has better low noise and dynamic characteristics compared with those using rotators. However, it has nonlinear characteristics due to the effect of slip that occur in the secondary eddy-current induction process; the normal force generated by the SLIM can negatively affect the levitation control. Therefore, a new slip-control algorithm is proposed for the safe operation of maglev trains, reflecting the normal force of the motor in propulsion control. First, the SLIM thrust and normal force are analyzed through the finite-element method (FEM) for a precise analysis of the slips. Furthermore, a slip range with a low normal force was derived based on the FEM analysis results, and these results are reflected in the propulsion control algorithm. Finally, the new algorithm was validated by an application to a full-sized testing apparatus.