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

Abstract

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, 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, 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.

A study on the design and characteristic analysis of LIM for the deep-underground GTX propulsion system

“…11, a negative value of the normal force means an attraction force. As a result, authors are able to confirm that the calculated thrust force value by FEM analysis is satisfied the traction force requirement when the LIM propulsion system travels within the deep-underground tunnel [6], [7]. IV.…”

Review of Linear Motor Topologies with Passive Secondaries and a Comparison to an Active Secondary Topology

“…Table II provides the sizing parameters of the machine after the optimization, while Fig. 8 shows the produced force and the attraction force of the single-sided topology over a displacement of 0.2 m. The force per mass is 45.6 N/kg, the force ripple equals 62.9 % and the motor efficiency is 83.4 %, according to (1).…”

“…The use of linear drives could well be one of those solutions. For example, the application of linear motors in railway or metro applications allows for stronger climbing ability, faster dynamic response, lower cost of maintenance (due to the simpler structure) and lower pollution compared to their rotational counterparts [1]- [8]. Furthermore, the use of linear actuators over mechanically belt-driven topologies could greatly enhance the thoughput of storage or airport transportation lines.…”

Life-cycle cost analysis of a short-haul underground freight transportation system for the DFW Airport

“…To guarantee the high performance and safety of the LIM operation, a uniform air gap between the primary and secondary must be kept fitted (Park et al , 2008). Therefore, periodic inspection and maintenance procedures are needed to ensure the energy efficiency and safety of the system.…”