Air-gap control system of a linear induction motor for a railway transit

In order to realize a traction system with high efficiency and performance for a railway transit, many researchers have continued to study on a linear induction motor (LIM). However, most of researches are limited in LIM unit design. On a moving LIM, the change of an air-gap (it occurs by a construction tolerance of a secondary reaction plate) can lead to decrease a smoother ride and efficiency of the railway transit system. Therefore, a uniform air-gap operation of the LIM is important issue to improve the system efficiency. However, the researches about the air-gap length control of the LIM have been not advanced a lot due to a technical and high-cost problem. Therefore, in this research, the authors introduce an air-gap control system to control the air-gap length which depends on the flatness of the secondary reaction plate when the LIM is been operating. Then, through a dynamic modeling and analysis of the system, the authors analyze characteristic variations of some parameters (spring coefficient, damping coefficient, displacement, and exiting force) which compose the system, and conduct a research on feasibility of the system.