Maglev Vehicle Research Articles

Dynamic Performance of Medium Speed Maglev Train Running Over Girders: Field Test and Numerical Simulation

With the ongoing development and deployment of medium-low speed maglev vehicles in China, it has become common to increase operational speeds from 100[Formula: see text]km/h up to 140[Formula: see text]km/h or even 160[Formula: see text]km/h, necessitating further studies and simulation models to understand the implications of these changes. This paper analyzes medium-speed maglev vehicle-track-girder coupling dynamic performance at a speed of 160[Formula: see text]km/h. First, a field dynamics experiment is carried out on the Changsha Maglev Express with a running speed of 80–140[Formula: see text]km/h. Then we introduce the distributed coupling simulation platform for maglev transportation system (MTS-DCSP) and the vehicle-track-girder coupling model, taking into account the complex vehicle structure, the guideway structure, and the Proportion Integral Differential (PID) levitation control system. Together, this platform and model can conduct a simulation of the complete process at scale and at all degrees of freedom to obtain accurate results. Our analysis of the results gives an accurate portrayal of the coupling dynamics properties and validates the coupling model. The results from the field experiments together with the coupling simulation demonstrate that the medium-speed maglev train can operate safely and stably within the range of 140–160[Formula: see text]km/h. While at 140[Formula: see text]km/h, however, the Sperling ride quality index (RQI) is about 2.5, which is within the Excellent grade range, at a speed of 160[Formula: see text]km/h, the Sperling ride quality index can increase to as high as 2.74, which is a grade of Good. Therefore, it is necessary to optimize the parameters of the secondary suspension system to improve the ride comfort of the maglev vehicle at 160[Formula: see text]km/h.

Vibration suppression of high-temperature superconducting maglev system via semi-active suspension system

Based on the flux pinning characteristics of non-ideal type Ⅱ superconductors YBa2Cu3O7-x, high temperature superconducting (HTS) pining magnetic levitation (maglev) is a self-stable levitation system with the merits of simple and reliable principle, friendly environment, etc. However, this maglev system is plagued by its prominent weak damping properties, which are unfavorable to the safety and comfort of the vehicle in operation under different external excitation. Therefore, the secondary suspension system should be added to this rail vehicle to enhance its damping property and its dynamic performance. This paper proposed a semi-active secondary suspension designed for the HTS pining maglev system. And this semi-active suspension can adjust the damping coefficient adaptively according to the motion state of the maglev vehicle. Moreover, an HTS pining maglev test vehicle "super maglev" is used to verify its effectiveness. Compared with the experimental and simulation results of a passive secondary suspension system, the dynamic performance of the maglev system with a semi-active suspension system is greatly improved. Furthermore, this semi-active suspension was applied to an engineering HTS pining maglev system through simulations. Eventually, through comparative analysis, the results show that the semi-active control damper controlled by PD can not only ensure the safety of passengers but also significantly improve the running stability of the vehicle, which has practical and economic advantages.

Dynamic guidance performance of GdBaCuO and YBaCuO bulk single grain superconductors under a varying external magnetic field

High temperature superconducting (HTS) maglev technology has attracted considerable attention from researchers around the world. It provides a new direction of development for urban rail and high-speed rail transit due to its considerable advantages of frictionless transportation, low noise, and environmental protection. HTS bulk materials are able to provide a significant performance advantage to maglev technology and are a key component to achieving both levitation and vehicle guidance. HTS bulk samples with enhanced flux pinning characteristics can enable improved curve negotiating ability and lateral stability for the maglev vehicle. This paper reports the results of experiments on the dynamic guidance force of single grain Y–Ba–Cu–O (YBCO) and Gd–Ba–Cu–O (GdBCO) bulk HTS single grains in order to explore their potential for enhanced maglev guidance performance. A customized HTS maglev dynamic measurement system (SCML-03) with a rotating, circular permanent magnet guideway (PMG) was employed to simulate the dynamic operation of the HTS vehicle above the PMG at different translational speeds. It was observed from the experimental results that the GdBCO bulk superconductor is more able to resist the attenuation of the dynamic guidance force compared to YBCO under the same operational conditions. In addition, the GdBCO bulk single grain is more able to return to the original equilibrium position following exposure to an external displacement. It is concluded that the GdBCO bulk single grain offers greater potential than YBCO for practical application in HTS maglev given its enhanced guidance performance. The results of these tests provide an important benchmark for the future design of HTS maglev transportation systems.

A Novel Moving Load Integration Method for Real-Time Hybrid Shaking Table Test of High-Speed Maglev Vehicle–Bridge Interaction System

Real-time hybrid shaking table test for high-speed maglev vehicle–bridge interaction (VBI) system is an important method to study dynamic response of the system. Numerical experiments are usually conducted in advance to guarantee the test performed smoothly. This paper presents a novel moving load integration method combined with a truncated bridge model for fast calculation of bridge responses, and presents a framework for performing numerical experiment of a real-time hybrid test of VBI system. A realistic numerical experiment is conducted on a real-time simulator, i.e. xPC Target, integrating three commercial software, i.e. SIMPACK, ANSYS, and MATLAB-Simulink[Formula: see text], to model a real TR08 single-carriage maglev train, a 5-spans bridge and 28 shaking tables, respectively. The driving speed is 400–600[Formula: see text]km/h and the time step size in the test is 1/256[Formula: see text]s. The accuracy of moving load integration method with truncated bridge model is verified, the effects of speed on the dynamic responses of VBI systems are studied, the time delay of shaking tables and compensation algorithm is investigated, and the effects of local nonlinearity of the bridge on system responses are studied. This paper provides a practical method and valuable reference for the real-time hybrid shaking table test of vehicle–bridge coupled systems.

Design of the Onboard Cryogenic System for High-Temperature Superconducting Maglev Vehicle

In the high-temperature superconducting (HTS) maglev system, the cryogenic system is used to eliminate the thermal load of the low-temperature unit in time to maintain the superconducting state of the superconductor, which is the prerequisite of the application. At present, liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) immersion cryogenic system is used in HTS maglev vehicles, but the operation efficiency of the vehicles will be reduced because of the LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> replenishment. Therefore, according to the application environment of HTS maglev vehicles, an onboard LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> natural circulation cryogenic system based on the principle of thermosiphon is designed. This paper focuses on the design of the structure of the cryogenic box, including the design of the vacuum system, the selection of refrigerator, the design of heat exchanger, and the selection of materials. Finally, it is calculated that the thermal load of the cryogenic system during the normal operation of the HTS maglev vehicle is 25.09 W, which is less than the cooling capacity of 120 W when the cryogenic system is working at 65 K. The feasibility of the cryogenic system is verified, which will provide a reference for the design of the cryogenic system in the engineering of the HTS maglev vehicles.

The SCML-05 Developed for Studying the 3D Force and PMG Irregularities Characteristics of HTS Maglev

In order to promote the application of high temperature superconducting (HTS) maglev vehicle, the series of superconducting maglev (SCML) measurement devices — 01, 02 & 03 have been developed in Southwest Jiaotong University. During the course of research, the importance of three-dimensional (3D) study of the interaction between HTS bulks and permanent magnet guideways (PMGs) has become evident. More specifically, when the HTS vehicle is moving at a high speed, small irregularities of the PMG's magnetic field become the source of vibration. Therefore, in order to study the 3D force and the characteristics of HTS maglev under PMG irregularities, a new measurement device called SCML-05 was designed, constructed, and validated. This newly developed measurement device consists of two major parts. The first one is a closed-loop sliding platform providing 3D motion. The second part is measurement and data acquisition system with the software developed for this purpose. In addition, a laser displacement sensor is used to measure the geometry irregularities of the PMG. Overall, the SCML-05 is flexible and light. The force characteristics of the HTS bulks placed above the PMG can be precisely investigated by means of this system. Additionally, the PMG irregularities including geometry and magnetic field irregularities can be measured. These parameters are required to analyze the relationship between the PMG irregularities and the force of HTS maglev vehicle. The test process and typical results obtained by this system are presented in this paper.

Maglev vehicle-switch girder coupled vibration characteristics analysis based on distributed co-simulation

The violent coupled vibration between the electromagnetically levitated vehicles and the steel switch girder had happened in several engineering practices, especially under the very low speed conditions. In order to simulate accurately the abnormal vibration and explore its underlying causes, this paper develops a distributed co-simulation framework, including maglev vehicle dynamic modelling by SIMPACK software, switch dynamic modelling by ANSYS software and a co-simulation coupler developed by C++ language to implement co-simulation of maglev vehicles and switch girder system. Dynamic response of maglev vehicles and switch girder system under various conditions of running speed and structural damping ratio are simulated and compared to obtain the mechanism and characteristics of coupled vibration. These results agree well with dynamic phenomena happened in the engineering practices. Further analysis shows that the levitation modules are impacted in turn by the vertical misalignments and rotation angles at both ends of switch girder, so that vibration energy of the switch girder cannot be attenuated rapidly by its relatively small damping and dead weight. The severe coupled vibration can be suppressed effectively by adding the tuned mass dampers, but improving constraints of switch girder and optimizing levitation control parameters should be paid more attention in the future.

A Mathematical Modeling and Analysis Method for the Kinematics of a Maglev Train

In recent years, more and more countries are paying attention to maglev transportation because of its outstanding advantages. However, because the structure of a maglev train is more complex than a wheel-rail train, there is no systematic theory method for kinematic modeling of a maglev vehicle. Based on the screw theory and the product of exponentials (PoE) formula in the field of open-chain robotics, this paper presents a method of kinematic mathematical modeling and analysis for a maglev train and track. By analyzing the characteristics of the closed chain running mechanism of a maglev train, the kinematic mathematical model of a maglev train and track is established, and the motion state of each moving part of the vehicle on a typical track is calculated and analyzed. At last, compared with the results of experiment, the correctness of modeling method proposed in this paper is verified.

Modelling dynamic interaction of maglev train–controller–rail–bridge system by vector mechanics

The dynamic coupling interaction of maglev train–controller–rail–bridge (TCRB) system has the potential to induce instability of travelling maglev trains. The conventional contact-type finite element model (FEM) method is difficult in modelling the TCRB system in the presence of non-contact levitation between the maglev vehicle and guideway and in incorporating the time-variant mechanism of suspension controllers in a high-dimensional FEM. In this study, we develop a new method, which endeavours to overcome the above difficulties, for modelling the maglev TCRB system and its dynamic interaction in the context of vector mechanics (VM). The VM underlies the principles on formulating vector form intrinsic finite elements (VFIFEs) to solve problems such as large deformation, large displacement, structural discontinuity, and non-contact mechanisms. In the VM formulation, we model the vehicle bodies, suspension bogies, and electromagnets as a collection of mass particles rigidly connected or linked by spring–dashpot units, with the levitation forces between the F-type rail and electromagnets being commanded by feedback controllers. Meanwhile, the guideway, including rail and bridge, is modelled as a group of mass particles linked by VFIFEs. The equations of motion for each mass particle are solved individually without need of assembling a global stiffness matrix, thereby eliminating the problems of ill-conditioning and numerical divergence. The proposed modelling method is validated by comparing the measured vehicle and bridge responses from a full-scale maglev train during its running on a test line with the computed results by the proposed method. After validation, the vertical and pitching resonant characteristics of the maglev system and the condition to invoke levitation gap resonance are evaluated.

Notice of Retraction: Three-dimensional Electromagnetic Characteristics Analysis of Novel Linear Synchronous Motor under Lateral and Yaw Conditions of MAGLEV

Dynamic stability analysis of superconducting electro-dynamic maglev train under lateral and yawing motion condition is the key research content. The novel three-dimensional electromagnetic model of integrated linear synchronous motor in electro-dynamic maglev train with yawing operation condition is proposed, which can not only simultaneously achieve the propulsion, levitation and guidance performances of maglev vehicle, but also analyze the dynamic stability performance of train with yawing condition. The three-dimensional analytical method is introduced for analyzing the electromagnetic force characteristics of the linear synchronous motor with the yawing operation condition. Firstly, the topology structure and operation principle of the linear synchronous motor with yawing attitude are proposed. Secondly, the three-dimensional analytical model and expressions of electromagnetic characteristics are obtained by equivalent circuit method and Fourier decomposition method, such as levitation force, guidance force, propulsion force and yawing torque, etc. Finally, the three-dimensional electromagnetic characteristics of the linear synchronous motor are calculated under yawing operation conditions of maglev train, and the correctness of the analytical theory is verified by the finite element analysis and measured data on the test line.

Research on Force Characteristics and Running Performance of Novel Type High-Temperature Superconductor Magnetic Levitation Vehicle

Research on Force Characteristics and Running Performance of Novel Type High-Temperature Superconductor Magnetic Levitation Vehicle

Theoretical optimization and experimental verification of a non-contact damper for high temperature superconducting Maglev systems

High-temperature superconducting (HTS) maglev has excellent potential in high-speed transportation due to its capability of passive stabilization levitation. However, in applications, the vibration of maglev vehicle with a large amplitude will be triggered for some external incentives or interference owing to its weak damping characteristics. Hence, it is preferable and necessary to find a way to reduce the vibration without mechanical contact. In terms of mechanical structure, the HTS maglev system mainly consists of HTS bulks and permanent magnets guideway (PMG). Utilizing the magnetic field provided by PMG, we designed and assessed an electromagnetic shunt damper (EMSD) for the HTS maglev system, by which the vibrations can be attenuated without contact. At first, the parameters of EMSD were theoretically optimized, respectively. Second, according to the structure of the Halbach PMG, the experimental EMSD was presented. In this damper, two groups of coils in reverse series were set above the two magnetic poles of the PMG to get a large induced electromotive force. Eventually, the experimental results show that the vibrations of the HTS maglev model vehicle can be attenuated more than 80% in the resonance region when the designed EMSD was employed in the system. Namely, this non-contacting damper will highly enhance the dynamic characteristics of HTS maglev systems.

Control of Time Delay in Magnetic Levitation Systems

The high-performance control of magnetic levitation (maglev) vehicles has encountered challenges in the form of time delays. In this letter, we model a reliable control method based on a Takagi-Sugeno fuzzy model aimed at solving the problem of air gap control of a magnetic levitation system for a maglev vehicle under time-delay conditions. The key idea is based on the global fuzzy model derived through sector nonlinearity to design a global controller utilizing the parallel distributed compensation method and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${H_\infty }$</tex-math></inline-formula> method. As a result, the stability of the system is guaranteed under conditions of mass parameter uncertainty, disturbance, and time delay. The theoretical analysis, numerical simulations, and experimental results consistently show the effectiveness of the control method.

Reinforcement Learning-Based Optimal Tracking Control for Levitation System of Maglev Vehicle With Input Time Delay

The running environment of a magnetic levitation (maglev) vehicle is complex, with problems such as track irregularity, external disturbance, varying system parameters, and time delays, which bring great challenges to the design of a high-performance levitation controller. In this article, an adaptive neural network controller with input delay compensation and a control parameter optimization scheme is proposed for the electromagnetic levitation system of a maglev vehicle, which can solve the key engineering problems of external disturbance, input time delay, and time-varying mass. Aiming at the problem of input time delay, a sliding-mode surface with time-delay compensation is constructed, and a double-layer neural network and adaptive law are utilized to approximate the uncertain dynamics; thus, a finite time adaptive tracking control law is proposed. Based on the Lyapunov method, the stability of the proposed controller in finite time is analyzed. The proposed method does not only update the input and output weights of the neural network online, but also introduces reinforcement learning (Actor&#x2013;Critic network) to optimize the key controller parameter in real time and enhance system robustness. Simulation and experimental results show that the proposed controller can effectively suppress the air gap vibration with time delay and uncertain dynamics, and significantly improve the performance of levitation control.

画像AIによる鉄道車両床下機器の外観状態判別手法の開発

To save labor and improve reliability of railway vehicle maintenance, we have been studying application of Artificial Intelligence (AI) technology to visual inspections of rolling stock equipment. This paper describes how we acquired appearance images for visual inspections, created training data and trained AI models. We built a practical AI development environment to find out what affects the judgment accuracy of AI models and how to improve accuracy through consistent creation and evaluation of AI models. Specifically, we worked on visual inspections of brake shoes for conventional trains and rubber tires for Maglev vehicle given importance of those parts. Our research established a procedure to develop highly precise AI models to distinguish conditions of railway vehicle underfloor equipment.

Optimisation of input power in linear induction motor (LIM) based Maglev vehicle

Maglev or magnetic levitation is an advanced technology in the modern world for high speed trains. The magnetically levitated train has no wheels, but floats on an electromagnetic wave. Maglev train system uses magnetic forces to levitate, guide and to propel the vehicle and the technology behind it enamored many countries worldwide. Different techniques have been proposed by the researchers, and a number of corridors have been selected and surveyed. This paper, describes a separate type of magnetically levitated train working model based on Linear Induction Motor (LIM) and permanent magnet. In this paper, the LIM is divided into three sections and the complete system performance is analyzed.

Experimental investigation on vibration characteristics of the medium–low-speed maglev vehicle–turnout coupled system

The steel turnout is one of the key components in the medium–low-speed maglev line system. However, the vehicle under active control is prone to vehicle–turnout coupled vibration, and thus, it is necessary to identify the vibration characteristics of this coupled system through field tests. To this end, dynamic performance tests were conducted on a vehicle–turnout coupled system in a medium–low-speed maglev test line. Firstly, the dynamic response data of the coupled system under various operating conditions were obtained. Then, the natural vibration characteristics of the turnout were analysed using the free attenuation method and the finite element method, indicating a good agreement between the simulation results and the measured results; the acceleration response characteristics of the coupled system were analysed in detail, and the ride quality of the vehicle was assessed by Sperling index. Finally, the frequency distribution characteristics of the coupled system were discussed. All these test results could provide references for model validation and optimized design of medium–low-speed maglev transport systems.

Dynamical Magnetic Resistance of HTS Maglev Vehicle in an Evacuated Tube Track

Based on the evacuated tube high-T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> superconducting (HTS) side-suspension (SS)-maglev circular track system which reached the maximum running speed of 160km/h, we studied the dynamical magnetic resistance of the maglev vehicle moving along the magnetic track. Different magnetic field gradients are formed by stacking silicon steel sheets on the surface of permanent magnet guideway (PMG) in this work. The running resistance of the prototype vehicle under different magnetic field gradients is acquired by processing the velocity attenuation data measured via acceleration sensor during the running process. The corresponding magnetic resistance is obtained by further data processing and analysis. A peak was observed in the low speed range of the speed dependent curve of the magnetic resistance, which can be attributed to the influence of the resonance. When the running speed of the maglev vehicle exceeds a certain value, the magnitude of magnetic resistance is positively related to the running speed and magnetic field gradient. The results of this study can provide a reference for the optimization of the manufacturing cost, performance, maintenance and safety in the application of HTS maglev vehicle.

Overview of Electrodynamic Levitation Technique Applied to Maglev Vehicles

Magnetic levitation vehicles are means of transport that move without touching the ground by the action of magnetic forces. The electrodynamic levitation technique uses the repulsive forces that arise from the interaction between any variable magnetic field and a good electrical conductor. This work aims to organize in a didactic manner the main topics involving electrodynamic suspension applied to Maglev vehicles, thus contributing to the understanding of the technique.

Vibration Characteristics of the New High-Temperature Superconducting Maglev Vehicle Based on Operation Test

A new HTS maglev vehicle called “KENYON” that can carry 8 passengers was successfully developed in December 2019. The vehicle adopted the bogie structure of independent running gear, which brings the improvement of curve passing performance. In order to further optimize vehicle curve passing performance in view of the small radius curve of the ring test line, corresponding experimental research was carried out in this paper. The experimental results show that the small wheelbase and centripetal arrangement were beneficial to improve the vehicle's curve passing ability.