Maglev Line Research Articles

An efficient dynamic reliability method for maglev vehicle-bridge systems and its application in random controller parameters analysis

This article presents an efficient method for analyzing the dynamic reliability of maglev vehicle-bridge coupled systems by combining a theoretical model with an adaptive surrogate model and the probability density evolution method (PDEM). First, a refined theoretical model of a maglev vehicle-bridge coupling system is established. Next, an adaptive surrogate model of the equivalent extreme value of the system dynamic response is established by combining an adaptive sampling method with radial basis functions. Finally, the adaptive surrogate model and PDEM are combined to further improve the efficiency of the dynamic reliability analysis. In the numerical example, the theoretical model of the maglev vehicle-guideway system was first validated by comparing with the measured data from the Shanghai high-speed maglev line. Then, by treating the controller parameters as normally distributed random variables, the accuracy and efficiency of the proposed reliability method were verified through comparison with the Monte Carlo method and the one-stage sampling surrogate model. Additionally, the impact of the randomness of each controller parameter and the coefficient of variation of the controller parameters on the system’s dynamic reliability was discussed.

Development of Simplified Methods for Levitation Force Distribution in Maglev Vehicles Using Frequency Ratio Tests.

Maglev vehicles apply the entire vehicle load uniformly onto bridges through levitation forces. In assessing the dynamic characteristics of the maglev train-bridge coupling system, it is reasonable to simplify the distributed levitation force as a concentrated force. This article theoretically derives the analytical response of bridge dynamics under the action of a single constant force and conducts numerical simulations for a moving single constant force and a series of equally spaced constant forces passing over simply supported beams and two-span continuous beams, respectively. The topic of discussion is the response of bridge dynamics when different degrees of force concentration are involved. High-precision displacement and acceleration sensors were utilized to conduct tests on the Shanghai maglev line to verify the accuracy of the simulation results. The results indicate that when simplifying the distributed levitation force into a concentrated force model, a frequency ratio can be used to analyze the conditions for resonance between the train and the bridge and to calculate the critical speed of the train; the levitation distribution force of a high-speed maglev vehicle can be simplified into four groups of concentrated forces based on the number of levitation frames to achieve sufficient accuracy, with the dynamic response of the bridge being close to that under distributed loads.

Research on Magnetic Levitation Control Method under Elastic Track Conditions Based on Backstepping Method

The vehicle–guideway coupled self-excited vibration of maglev systems is a common control instability problem in maglev traffic while the train is suspended above flexible girders, and it seriously affects the suspension stability of maglev vehicles. In order to solve this problem, a nonlinear dynamic model of a single-point maglev system with elastic track is established in this paper, and a new and more stable adaptive backstepping control method combined with magnetic flux feedback is designed. In order to verify the control effect of the designed control method, a maglev vehicle–guideway coupled experimental platform with elastic track is built, and experimental verifications under rigid and elastic conditions are carried out. The results show that, compared with the state feedback controller based on the feedback linearization controller, the adaptive backstepping control law proposed in this paper can achieve stable suspension under extremely low track stiffness, and that it shows good stability and anti-interference abilities under elastic conditions. This work has an important meaning regarding its potential to benefit the advancement of commercial maglev lines, which may significantly enhance the stability of the maglev system and reduce the cost of guideway construction.

Distributed virtual simulation experimental software for high-power electric traction system of 600 km/h high-speed maglev train

The operational speed of high-speed maglev trains has reached a groundbreaking 600 km/h, facilitating faster intercity transportation. However, the design and verification of corresponding high-power electric traction systems face significant challenges. To address these issues, this study develops a distributed virtual simulation experimental software for the high-power electric traction system of a 600 km/h high-speed maglev train. The software first establishes virtual digital models for the high-speed maglev train, the high-speed maglev guideways, and the high-power electric traction converters to simulate the high-speed maglev line operation scenarios. Next, it constructs a client–server simulation software architecture, designs a human–machine interaction platform and an electric traction mathematical module, and devises an information exchange method to enable real-time tracking and display for the operating conditions of high-power electric traction systems. Lastly, by integrating electric traction control strategies, fault analysis and optimization design modules, the software effectively designs and verifies the optimal electric traction systems of high-speed maglev trains, and promptly identifies the potential faults in long stator linear synchronous motors and high-power electric traction converters within the electric traction systems. Engineering applications demonstrate that the software can significantly enhance the design and virtual simulation efficiency for the high-power electric traction systems of high-speed maglev trains, thus meeting critical engineering application needs.

Train headway estimation for maglev with blocking time theory

As the commercialization of maglev trains continues to accelerate, effective improvement of maglev train operation has become a topic for researchers. The train headway of the maglev is the preparation basis for the train timetable and is also an essential factor affecting the line capacity utilization. This paper proposed an approach to estimate the train headway by considering the characteristics of partitioned control of maglev operations. First, we build the tracking model for maglev with the theory of blocking time, in which the train speed profile is the key input source. Then, a customized method is proposed to estimate the minimum headway of maglev trains. According to the experiment, we can effectively obtain the minimum train headway by the approach, and the result of improving the maglev line capacity utilization is verified.

Control of the maglev system with a low stiffness elastic track beam by pole assignment and a reduced order state observer

A maglev train system is an open loop unstable and strongly nonlinear system. Self-excited coupling vibration between the magnet and the track beam can occur even when the train is stationary. To avoid this, the track beam is generally designed with high stiffness, which directly increases the construction cost of the maglev line. In this research, a new control method for the maglev system with a low stiffness elastic track is proposed based on full state feedback theory and pole assignment theory. In the newly designed controller, track beam DOF is introduced into the control loop with the use of the reduced order state observer (ROSO) to make the control system have the ability to suppress track vibration actively, thus reducing the over dependence of the system stability on track properties. Effectiveness of the proposed control strategy is verified through experiments. Results show that it exhibits a better response compared to the traditional control method, with smaller fluctuations in levitation air gap and magnet acceleration. Furthermore, it can maintain system stability with relatively lower track stiffness, reducing the minimum requirements for track stiffness by 53.4% in the test.

Research on Environmental Vibration Induced by High-Speed Maglev Transportation

As a novel form of railway transportation, maglev transportation has the advantages of a better curve negotiation ability and grade ability and lower noise and vibration than traditional urban wheel–rail transportation. Thus, it is suitable for use in urban public transportation. However, the levitation of the widely utilized electromagnet suspension (EMS) system relies on continuously active suspension force adjustment, which gives it vehicle–track-coupled vibration characteristics different to those of the traditional wheel–track transportation system. Despite many research studies focusing on maglev vehicle–track coupling vibration, the environmental vibration influences associated with the running of maglev trains are still unclear. When the vibration propagates to the surroundings beyond certain thresholds, it may lead to various vibration serviceability problems. Practical test results on the environmental vibration induced by maglev transportation are still not enough to generate convincing vibration propagation and attenuation laws. In this research, a series of in situ tests were carried out around the Shanghai maglev line; the results show that the viaduct bridge is helpful in reducing environmental vibration, and an empirical formula was proposed to predict the effect of viaduct column height. Due to the ground wave superposition, a vibration-amplifying zone was also found about 10 m away from the maglev line, in which the vibration magnitude was strong enough to be perceived by the surrounding occupants.

Dynamic Reliability Analysis of Running Safety and Stability of a High-Speed Maglev Train on a Guideway Bridge

The dynamic performance of high-speed maglev trains, a next-generation rapid transit system, has received continuous attention in recent years. In this study, a dynamic reliability analysis method for a high-speed maglev train–guideway coupled system was proposed. First, a refined model of the maglev vehicle–bridge interaction system was established, where the vehicle subsystem was simulated as a rigid body-spring-damper model with 101 degrees of freedom. The guideway subsystem was simulated as a finite element model, and these two subsystems were coupled as an entire system through a magnet–rail interaction model with a proportional-derivative (PD) controller. Second, a dimension-reduction method for the simulation of representative samples of track irregularities was developed, and thus the number of random variables in the system was reduced to four. Finally, an efficient method for the calculation of the dynamic reliability of a maglev train–guideway coupled system was proposed using the probability density evolution method-based equivalent extreme value principle. With numerical examples, the accuracy of the maglev train–guideway interaction model was verified by comparing it with field measurement data from the Shanghai high-speed maglev line. The accuracy of the proposed dynamic reliability analysis method was confirmed by comparing three types of results, that is, the mean value time-history curve, the probability density function, and the cumulative distribution function of extreme values, obtained by the Monte Carlo method. Finally, the dynamic reliability of the running safety and stability of the maglev vehicle at a speed of 430 km/h and the variation laws of the dynamic reliabilities with train speed were examined in detail.

Measurement and numerical analysis on dynamic performance of the LMS maglev train-track-continuous girder coupled system with running speed-up state

Improving the target running speed on original maglev lines is an economical method to meet the social development demands. With the speed improvement, maglev train-track-bridge system coupled vibration is intensified, seriously affecting the train’s moving stability. For this study, vibration performance about the coupled system at measured speeds (100 km/h–150 km/h) are investigated based on field test; then a refined numerical coupling vibration model is developed and validated; finally, vibration characteristics at target speed of 160 km/h are studied by simulation. Results show the accelerations of maglev vehicle increase significantly when running speeds exceed 140 km/h, and F-rail’s acceleration is noticeably larger than that of continuous girder and sleeper. The results of this numerical model agree well with those of the field test. When the speed reaches the target of 160 km/h, the amplitude increases in time domain, and dynamic responses are within a reasonable range and meet the standard requirements.

Energy‐efficient train timetabling for a medium‐speed maglev line considering propulsion and suspension energy consumption

AbstractThis paper addresses the energy‐efficient train timetabling problem for MSM systems, where both propulsion and suspension energy consumption are considered. The timetable design problem is modelled as a bi‐level model for a complete two‐way MSM line. The upper level determines the train departure time at the first station, which makes train operations more convenient for passengers. The lower level uses an empirical description of the train energy consumption as a function of segment running times, and an energy‐efficient timetable optimization model is built. In doing so, all the services in both directions along a certain planning horizon are considered while attending to a known passengers’ demand. Moreover, the convenience of considering energy consumption as part of a broad objective function that includes other relevant costs is pointed out. Then, a unified sequential solution algorithm is developed for an efficient and accurate solution of the bi‐level model. Experiments show that the proposed framework can generate a holographic timetable of energy‐efficient MSM containing multi‐dimensional variables such as time, space, velocity, and electrical quantities.

Stability Simulation and Analysis of Maglev Vehicle at Different Speed Based on UM

High-speed maglev train is an excellent mode of transportation to build a transportation network because of its high safety, low emission, low energy consumption, low noise and strong climbing ability. The safety, stability and comfort of high-speed maglev train are closely related to the running speed and the random track irregularity, so it is necessary to study the corresponding relationship between the running speed, the random track irregularity and the stability. In order to ensure the safety and stability of high-speed maglev train in high-speed running, a dynamic model of high-speed maglev vehicle is established by UM based on Shanghai TR08 maglev train to carry out simulation analysis of its response to various track irregularity stimulations at different speeds and study the change law of stability of maglev train at different speeds, so as to provide a useful reference for the design optimization of high-speed maglev vehicle and the irregularity control of maglev line.

Analysis of the Speed Limit of Transrapid Maglev Train Explored From the Perspective of Its Suspension and Guidance Systems

In recent years, research on high-speed or ultra-high-speed maglev systems has become increasingly popular, and different countries or teams have been committing to several different suspension technologies. Among them, due to the profound accumulation of research on the normal-conducting electromagnetic suspension technology, China is actively adopting this suspension technology to develop a new high-speed maglev train faster than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$600~km/h$ </tex-math></inline-formula> , and this work is mainly on the basis of Transrapid (TR) trains and Shanghai Maglev Line (SHML). To evaluate the feasibility of this project, the speed limit of the TR maglev system was explored from the perspective of its suspension and guidance systems. The analysis process was carried out from two aspects of aerodynamic interference and track irregularity. As for aerodynamic interference, the aerodynamic and electromagnetic simulation models were established based on the actual maglev train. The anti-interference abilities of the suspension and guidance systems were analyzed from two aspects of steady-state and transient-state respectively. The results verified that the train could operate safely when its speed below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$800~km/h$ </tex-math></inline-formula> and the cross-wind speed below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$26~m/s$ </tex-math></inline-formula> . As for track irregularity, based on the actual track construction indicators of the SHML, the relationship between suspension gap fluctuation and the train speed was studied through a dynamic calculation model of the suspension control system. The results showed that the suspension system had a risk of track collision when the train speed was greater than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$717~km/h$ </tex-math></inline-formula> . In summary, from the perspective of its suspension and guidance systems, the current TR maglev system on the SHML has an upper speed limit. The conclusion would be valuable for the development of ultra-high-speed maglev systems in the future.

Random vibration analysis of the maglev vehicle-guideway system using a probability density evolution method with uncertain parameters

Random dynamic analyses of maglev vehicle-guideway coupled systems are of significant interest but have yet been comprehensively performed. This paper presents a time-dependent coupled random model of a maglev vehicle-controller-guideway-pier to investigate random vibration characteristics of the dynamic system. In the study, a 12-degree-of-freedom vehicle model is considered, a three-dimensional detailed guideway model is established using the finite element method, and the electromagnetic levitation force is controlled with a current feedback controller. Then, the generalized F-discrepancy representative point set selection strategy and probability density evolution method, which can consider multiple random parameters, are combined to analyze the dynamic system. Random vehicle parameters and irregularity are introduced and the mean value, standard deviation, limits satisfying different probability guarantee rates, and probabilistic information are calculated. The model was validated with field measurement data from an electromagnetic suspension (EMS) maglev line. In addition, the Monte Carlo method was used to assess the accuracy and efficiency of the proposed method. The results demonstrate that the proposed method has good accuracy and efficiency. The effects of vehicle running speed, random irregularity, and random vehicle loads on the dynamic vibration of the system are discussed.

Impacts of the opening of the maglev railway on daily accessibility in Japan: A comparative analysis with that of the Shinkansen

The Shinkansen, the first high-speed rail (HSR) service in the world, started operations in 1964 in Japan, where the world's first long-distance intercity magnetic levitation (maglev) line will open in 2027. In light of this, the study evaluated time-series changes in railway accessibility in Japan. The impact of opening the maglev line on accessibility was investigated by comparing it to Shinkansen. Accessibility was measured by modifying a daily accessibility model to include the concept of distance decay. Daily accessibility significantly increased between 1961 and 2000 with Shinkansen's development. However, after 2000, this trend weakened, and accessibility did not increase much in most cities. Comparing accessibility changes from 1961 to 1980 and those projected for 2020 to 2040 suggests that the impact on accessibility from maglev services will be smaller than that of Shinkansen for two main reasons. First, the reduction in travel time will be smaller because many Shinkansen lines will already be operating between large cities when the maglev line opens. Second, most of the positive effects of reduced travel time from the maglev line are negated by countrywide depopulation and a population concentration in metropolitan areas. The maglev line's effects are offset by depopulation. Therefore, parallel policies to increase the maglev line's effects must be implemented. In the rare case of Japan, where the HSR network has already expanded and the population is declining, the cost-effectiveness of maglev will be small. However, in many countries where such conditions do not apply, maglev lines are expected to be more effective.

Field experimental tests and analyses of suspension frame vibration of low-medium speed maglev train

Pushed by social demands, China has continuously developed its low-medium speed maglev transportation systems in recent decades. However, with the increase of the running mileage of the train, high frequency vibration of suspension frame gradually appears. In this paper, a method to analyze the high frequency vibration of suspension frame by detecting the current of traction motor is proposed. Field measurements of suspension frame vibration and traction motor current of low-medium maglev train were conducted on a maglev line that has been commercially put into operation. The test results show that the speed of the measured maglev train was closely correlated with vibration accelerations of the suspension frame in three directions, but as the speed increased, the influence it imposed on the suspension frame vibration waned. The dominant frequency of traction motor resultant current was consistent with the dominant frequency of the suspension frame vibration acceleration. The switching frequency of traction inverter was the main cause of high frequency vibration of suspension frame.

Prediction Approach of Negative Rail Potentials and Stray Currents in Medium-Low-Speed Maglev

The problem of negative rail potentials (NRPs) appears in the line of the medium-low-speed (MLS) maglev. It is vital to forecast the NRP and the corresponding stray currents (SCs) in order to prevent safety hazards. This article proposes the prediction methods of NRP and SC for the first time for the MLS maglev. On the basis of developing a two-layer rail–earth circuit, a simplified prediction approach based on the analytical formula derivation is proposed to obtain the behaviors of NRP and SC under different steady running scenarios. Afterward, in order to accurately reveal the influence of vehicle-grid parameters, the ac component and the energy dispersal path of the maglev system are detailed, and the precise vehicle-grid model is developed to consummate the prediction approach using MATLAB. Under the premise of verifying the scheme effectiveness using the captured data in the on-site of the Chinese Xinzhu MLS maglev line, the scheme application studies are provided to investigate the behaviors of NRP and SC while considering the ac effect and the varying velocity of load current and rail–earth conductivity.

Dynamic Interaction Analysis of High-Speed Maglev Train and Guideway with a Control Loop Failure

The fault of a control loop can occur when a high-speed maglev train is running on guideways, which will affect the dynamic responses of the maglev train and guideway and is one of the controlling cases in the design of guideway functional parts. To study the dynamic response of the vehicle and guideway when a control loop failure occurs, first, a spatial coupling vibration model, which includes the three-dimensional (3D) maglev trains, guideways, piers and electromagnetic force based on the proportional-derivative (PD) controller, is proposed, and the electromagnetic force model for a control loop failure is presented. Second, the effectiveness of the coupling vibration model is verified based on the measured results of the Shanghai maglev line (SML). Finally, the dynamic responses of maglev train and guideway are discussed under a suspension magnet or guidance magnet with a control loop failure, and the influences of the location of the fault, the weight of the vehicle and the preload of the guidance system are analyzed. The most disadvantageous load value acting on the functional parts in case of magnet failure is obtained. The results show that the dynamic responses of the maglev train with a control loop failure will vary due to the location of the fault on trains and guideways, the weight of vehicle and the lateral preload. Although a control loop failure has little influence on the dynamic response of the guideway, the suspension force or guidance force on guideway will increase suddenly, and this sudden force is far larger than the vehicle static load or lateral preload of guidance magnets.

Numerical Analysis of Subgrade Behavior under a Dynamic Maglev Train Load

Medium‐low‐speed maglevs are increasingly used in the urban rail transit industry because of their advantages, such as low noise and low energy consumption. In this study, a finite element analysis of the responses of the subgrade that supports a medium‐low‐speed maglev structure under a dynamic maglev load is presented. First, the finite element analysis considers a low‐lying structure with different elastic moduli. Then, the attenuation laws of the dynamic stress and dynamic deformation for different depth ranges of the subgrade under the rail beam are analyzed. In addition, the magnitude of the influence of the dynamic load is clarified. The results lead to a recommendation of a base bed thickness of 1.5 m, graded gravel or group A filler as the surface layer of filler, and gravel soil as the bottom layer. This study provides theoretical support for the construction design of a subgrade structure under the rail beam of a low‐lying maglev line.

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.

Hyperloop transport technology assessment and system analysis

ABSTRACT The Hyperloop concept, pod speed competitions and current project developments have recently attracted much publicity. In this paper the transport technology of the vacuumed tube transport project Hyperloop is assessed through a system analysis of its principal aims, functional design, transport capacity and demand in comparison with existing commercial airlines, high-speed rail, and Maglev lines. First, the potential for high-speed long-distance travel demand for Hyperloop based on existing airline transport volumes between major airports in Germany on the one hand, and the proposed Hyperloop link from Los Angeles to San Francisco in California on the other, is assessed in general terms. Second, the technical feasibility of the proposed Hyperloop concept for vehicle design, capacity, operations, propulsion, guidance, energy supply, traffic control, safety, alignment, and construction is discussed in more detail. Third, possible environmental impacts and uncertain investment, operating and maintenance costs for implementation of a Hyperloop line are described. Finally, the risks for further Hyperloop project development and the need for more transparent research are emphasized.