In recent years, the high-speed rail train has achieved great progress, but the wheel-rail relationship and the catenary-pantograph relationship are the bottleneck to further increase the speed. The maglev train is a entirely new mode of transport without wheels. It takes full advantage of electromagnetic force to achieve active levitation and runs the train by the linear motor. It completely abandons the frictional resistance to speed up over 500 km/h practicably. The redundancy and fault tolerance of magnetic levitation system, which is considered as the wheels of high speed maglev train, play a major role in the safety and reliability of high speed maglev train. However, due to the failure of sensors and the existence of track seams, the suspension unit often breaks down. The performance of suspension join-structure under the modular redundancy strategy with sensor failure is analyzed and investigated. The investigation carried out by us reveals that the overall performance is unpleasant and the electromagnet fevers seriously. In order to solve this problem, we propose and design the state observer as a solution to construct the fault-tolerant control system. The designed observer is applied to estimate the gap measurement of fault sensor so that the suspension unit will not fail. Therefore, The fault-tolerant control system based on state observer improves the redundancy and fault tolerance capacity of magnetic levitation system with sensor failure significantly.

The commercial operation of the maglev train puts critical demands on reliability and operation performance. Since maglev trains' levitation system is open-loop unstable, its closed-loop stability under various operation conditions is a primary consideration. This paper thus addresses real-time stability performance monitoring and evaluation of maglev trains' levitation system. First, a novel real-time performance indicator for stability performance monitoring is proposed. It utilizes only the online data of the levitation system, without knowing its accurate model. Then, performance evaluation is carried out by grading the monitored stability performance into different levels for further handling. Moreover, the proposed methods offer a way of controller evaluation for the levitation system before the train is put into commercial operation. It is noteworthy that, the proposed methods do not require the model of the levitation system to be known and run in real-time. The effectiveness and efficiency of the proposed methods are validated on a levitation system.

The guidance system is one of the important subsystems of high-speed maglev train. The active guidance of high-speed maglev train is achieved by the attraction between the guide way and the electromagnets mounted on the side of the carriage. The working characteristics of the guidance system vary according to the different guide ways and weather conditions. In the straight line, the guiding current is very small. When suffering from the bend or big crosswind, the guiding current will be very large. Therefore, the model of the guidance system has greater uncertainty, and the guidance controller is more difficult to design. This study is conducted to make the high-speed maglev train obtain a stable guidance ability on different conditions. The mathematical model of guidance system is established, and the robust guidance controller is designed by H∞ control theory. The simulation and experiment demonstrate that the high-speed maglev train using the designed guidance controller has relatively desirable performance and achieves stable guidance ability successfully.

The maglev train is a whole new method of transportation without wheels, consisting of 20 groups of symmetry suspension units. The magnetic levitation system plays a major role in suspending the maglev train stably and following the track quickly with the desired gap. However, vertical track irregularity in the maglev train line has a dreadful effect on the tracking performance of the magnetic levitation system. The investigations carried out by our team have revealed that the fluctuation of the suspension gap becomes more and more serious with increases in running speed. In this paper, a mathematical model with consideration of vertical track irregularity is established. In order to overcome and suppress the fluctuation of the suspension gap, we propose a new strategy which includes installing an accelerometer on the electromagnet to address this problem. This strategy has already been successfully implemented and applied to the suspension controller for a magnetic levitation system in the Changsha maglev express. Real operation data indicates the tracking performance of the magnetic levitation system was obviously improved.

The high-speed maglev train adopts active control through the suspension unit to maintain the specified distance above the track. In the presence of flexible track conditions, even if the train is not running, the train-track coupling vibration may occur. The research focuses on analyzing the coupled vibration of the train-track system under elastic track conditions, establishing a simplified and reasonable model of the coupled vibration, and devising a controller with pre-compensation and full-state feedback to ensure closed-loop stability and accurate reference tracking. The research further investigates the impact of various factors on the coupled vibration by modifying key parameters for obtaining root locus plots. Numerical simulation analysis is employed to assess the influence of control parameters on the coupled vibration. Based on the law of the influence of the control parameters, the suppression of the coupled vibration of the system was successfully achieved by adjusting the control parameters in the event of vehicle-track parameter mismatch. Finally, experiments were conducted on the Qingdao high-speed maglev train to verify the effectiveness of the proposed model and full-state feedback control algorithm.