A Reference Model Assisted Adaptive Control Structure for Maglev Transportation System

Maglev transportation system is become a hot topic for researchers because of the distinctive advantages, such as frictionless motion, low power consumption, less noise, and being environmentally friendly. The maglev transportation system’s performance gets sufficiently influenced by the control method and the magnetic levitation system’s dynamic performance, which is a critical component of the maglev transportation system. The Magnetic Levitation System (MLS) is a group of unstable, nonlinear, uncertain, and electromagnetically coupled practical application. Control objective of this study is to design a position stabilizing control strategy for Magnetic Levitation system under extreme uncertain parametric conditions using a reference model governed by a reference stabilizer and nonlinear adaptive control structure. After successful tuning the reference stabilizer with and without time-varying payload disturbance, the tracking-error dynamics are obtained in the presence of both matched and mismatched types of parametric uncertainties. Next, the close-loop stability theorem is formulated for Lyapunov stability analysis to get the design constraints, parameter update laws, and adaptive control law. Numerical simulations performed for a high range of parametric violations check the control design’s efficacy. The performance robustness gets confirmed by comparing the results with the nonlinear control approach. The MLS gets performance recovery and settles within safe limits in few seconds using the proposed methodology. However, the nonlinear controller faces permanent failure in stabilizing the MLS.

Vertical Dynamic Response Prediction of the Electromagnetic Levitation Systems

Due to the limited deviation range of the controllable levitation gap, the vehicle/track coupling dynamic problem of the maglev transportation system is very prominent. The stability of the electromagnetic levitation system is deeply affected by the track irregularity. It is found that there are obvious dynamic characteristic differences of the electromagnetic levitation system, and the deviation range of the levitation gap increases gradually with the increase of the train speed. This paper presents a vertical dynamics prediction method of the electromagnetic levitation system. Firstly, the model of the electromagnet module and the track is established. Then, the amplitude spectrum functions of the levitation gaps are obtained by using the discrete frequency excitation method. Based on the amplitude spectrum functions, the vertical dynamic response of the levitation system can be predicted. The amplitude spectral analysis results are consistent with the numerical simulation results.

Analysis and solution of eddy current induced in rail for medium and low speed maglev transportation system

Background: For medium and low speed maglev transportation system, the eddy current will be induced in rail, which is made of solid steel, while the train is running. The levitation force of electromagnets will be weakened by the magnetic field generated by eddy current in the rail, especially at the position of the forefront electromagnets. With the increase of train running speed, the eddy current effect will also increase, which will reach 30 % at 100 km/h, and which will directly affect the levitation stability of the train during high-speed running. Put it another way, it will limit the further improvement of the running speed of the medium and low speed maglev train. Aim: In order to solve the above problem, and compensate the levitation force reduced by the eddy current effect. Methods: The FEA method is used to obtain the magnetic field distribution and levitation force changing with the train speed. And taking the middle and low speed maglev trains and rails of Changsha Maglev Express as the research object, we have adopted two solutions, and the prototypes of airsprings and levitation magnets are manufactured and tested in the train. Results: The test result show that the currents of the windings at the front end of the two forefront electromagnets are reduced obviously. Conclusion: In this paper, the medium and low speed maglev train and rail used by Changsha Maglev Express are studied, the eddy current effect is analyzed, and two solutions are proposed. The results show that the solution methods can alleviate the eddy current effects to some extent.

Design of a MIMO Levitation Controller for Maglev Transportation System

In this paper, the levitation control method of a MIMO Magnetic Levitation (Maglev) transportation system with 3-DOF is presented. Fluctuations of magnetic poles cause the Maglev system to become critically unstable. We propose a design method of the MIMO Maglev controller based on SISO Maglev control technology to correct the suspension and compensate for the effect of rotational motions. In addition, a force loop controller is designed for placement in front of each sub-controller of an electromagnet for stability improvement. The proposed control method is evaluated using simulations and real experiments using the developed Maglev transportation system.