492 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 39, NO. 1, JANUARY 2011 A Novel Magnetic-Levitation System: Design, Implementation, and Nonlinear Control Ugur Hasirci, Abdulkadir Balikci, Zivan Zabar, Senior Member, IEEE, and Leo Birenbaum, Senior Member, IEEE Abstract—This paper concerns the design, implementation, and nonlinear velocity-tracking control of a novel magnetic-levitation (maglev) system for magnetically levitated trains. The proposed system uses only one tubular linear induction motor to produce three forces required in a maglev system: propulsion, levitation, and guidance. Classical maglev systems, on the other hand, con- tain a separate force-generating system to build each of these three forces. Another benefit that the proposed system offers is that there is no need to control the guidance, and particularly, the levitation forces, one of the most challenging tasks in maglev systems. The system always centers the moving part during op- eration and eliminates the necessity for control of the levitation and guidance forces. However, the propulsion force strongly re- quires some control efforts because a linear induction motor has nonlinear system dynamics. This paper gives a condensed design guideline based on the mature theory of electromagnetic launch- ers, particularly the linear induction launcher type. It explains the implementation process, shows experimental test results, and finally, presents a nonlinear partial state-feedback controller for the proposed system. Index Terms—Electromagnetic launchers (EMLs), linear induc- tion launchers (LILs), magnetic-levitation (maglev) trains, nonlin- ear control. I. I NTRODUCTION M AGNETIC-LEVITATION (maglev) technology elimi- nates mechanical contact between moving and station- ary parts. This implies that this technique also eliminates the friction problem. Therefore, it finds many application areas like magnetic bearings [1], vibration isolation [2], and high- speed rail transportation [3]. Maglev trains provide a powerful alternative to land, air, and classical rail transportation. In particular, they can serve as a reliable, high-speed, and envi- ronmentally friendly option to mass transportation. Although it is possible to find many different configurations since it was first proposed [4], where more mature studies are generally based on [5]–[7], a maglev system must basically produce three Manuscript received January 11, 2010; revised April 2, 2010; accepted June 1, 2010. Date of publication July 23, 2010; date of current version January 7, 2011. This work was supported in part by The Scientific and Technological Research Council of Turkey (TÜB ˙ ITAK) under Grant 107E107. U. Hasirci is with the Electronical Engineering Department, Gebze Institute of Technology, Kocaeli 41400, Turkey (e-mail: uhasirci@gyte.edu.tr). A. Balikci was with the Department of Electrical and Computer Engineering, Polytechnic Institute of New York University, New York, NY 10004 USA. He is now with the Electronical Engineering Department, Gebze Institute of Technology, Kocaeli 41400, Turkey (e-mail: a.balikci@gyte.edu.tr). Z. Zabar and L. Birenbaum are with the Department of Electrical and Computer Engineering, Polytechnic Institute of New York University, New York, NY 10004 USA (e-mail: zzabar@poly.edu; lbirenba@duke.poly.edu). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPS.2010.2053389 forces: a propulsion force to push the moving part forward, a levitation force to lift up the moving part, and finally, a guidance force to avoid derailing. Generally speaking, classical maglev systems use three separate force-generating systems to produce these forces. This implies that many sensors, drive, and control systems are needed for the operation of the system. However, a novel topology, patented by Levi and Zabar [8] and focused on the use of the linear induction launcher (LIL) [9] for maglev systems, proposes the use of only one linear induction motor to produce the three forces. The theory of operation and experimental results [10] of the LIL shows that the proposed system centers the moving part during operation, and this eliminates the necessity for control of levitation and guidance forces. A LIL is an air-cored coil gun operating on the same principle as linear induction motors. It is composed of two main parts: a stationary part, called the barrel, consisting of a linear array of drive coils energized in a polyphase fashion so as to create a traveling magnetic wave, and a moving part, termed the sleeve, consisting of a hollow aluminum cylinder enveloping the projectile [11]. The traveling magnetic wave created by the polyphase current flowing in the drive coils induces currents in the projectile, and the interaction between the traveling magnetic wave and the currents induced in the projectile creates the thrust, as shown in Fig. 1. The interaction between the traveling magnetic wave and the azimuthal currents induced in the projectile generates not only propulsive forces but also radial forces. The latter center the projectile during transit [11]. Interest in the LIL is due to the benefits it offers: centering and guidance of the projectile along the barrel, enhanced barrel survivability, low cost, and simple structure. These benefits, particularly the one that the system always centers the moving part, enable the idea to be used in an innovative way for maglev systems. Fig. 2 shows the proposed maglev system inspired by the LIL. This system has two main parts: a primary, consisting of the drive coils, and a secondary, consisting of a slit aluminum sleeve. Drive coils can be placed either onboard the vehicle, as shown in Fig. 2, or on the track. The theory of operation of the proposed system can be explained as follows: Three- phase excitation currents in the drive coils create a traveling magnetic wave, which induces currents in the aluminum sleeve. The current induced in the sleeve cuts the lines of flux that are generated by both drive and sleeve coils. The flux density can be decomposed into two directions, one in the longitudinal direction and one in the radial direction. The flux-density component in the radial direction and the circumferential sleeve current generate a force in the longitudinal direction, i.e., the 0093-3813/$26.00 © 2010 IEEE