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The permanent magnet electrodynamic suspension (PMEDS) owns the promising application prospect, due to its simple structure, low cost and reliable load capacity. However, the underdamping of the PMEDS system is still a challenge in engineering applications of transportation. This paper proposes a passive damping method and its implementation structure to improve the underdamping characteristics. This method utilizes the inherent magnetic leakage of on-board magnets technically. The principle of passive damping and its implementation structure is introduced in detail. And the kinetic models of ordinary and improved structure are established based on the topology graph. Besides, the magnetic field and the electromagnetic force involved in the kinetic models are analyzed, and the numerical analysis method of the drag force is verified by the high-speed test rig. Furthermore, the performance of passive damping is verified by finite element method (FEM) and the time-domain response analysis. The results show that the improved damping structure can effectively suppress vibration and improve the dynamic stability of the PMEDS system. It is beneficial to the engineering application of the PMEDS in the future. [ABSTRACT FROM AUTHOR]

In principle, high-temperature superconducting (HTS) flux-pinning maglev has the advantage of self-stable levitation and is therefore a good development prospect as a new rail transit technology. The magnetic field intensity is one of the key factors affecting the levitation performance of single-grain bulk superconductors in the HTS maglev system. To date, however, most researchers have focused on the levitation performance of HTS bulk superconductors in magnetic fields within a permanent magnet guideway (PMG) configuration. The magnitude of the external working magnetic field provided by a PMG is limited to about 0.5 T at 77 K, given that the superconductor usually levitates at a typical working height of 10 mm above the PMG. Therefore, the weak magnetic fields generated by the PMG significantly limits the levitation performance of HTS maglev systems to that of the permanent magnet (PM). In this article, a superconducting magnet test bench was utilized to provide a 0–3 T external magnetic field (B) environment for the study of the levitation force in HTS single grains. The difference in levitation performance between YBaCuO (YBCO) and GdBaCuO-Ag (GdBCO-Ag) bulk superconductors under large, changing magnetic fields was studied systematically. The relationships between levitation force and magnetic field characteristics, including vertical magnetic field component (Bz), transverse magnetic field component (Br), and vertical magnetic field variation (ΔBz) were investigated. The result of variation curves about YBCO and GdBCO bulks' levitation forces under different ΔBz shows that the levitation force of the bulk, single-grain superconductors will reach saturation under a varying ΔBz environment (0.72 and 1.5 T). The values of ΔBz corresponding to the saturation positions are found to be independent of the sizes of the HTS samples. At the same time, GdBCO-Ag exhibits a levitation force that is 112.8% greater than YBCO in B = 3 T magnetic environment. As a result, it is demonstrated that the levitation potential of single-grain HTS bulks can be better exploited by optimizing the distribution of the magnetic field. [ABSTRACT FROM AUTHOR]

A novel type of suspension system for maglev vehicles using six permanent magnet electrodynamic wheels (EDW) and conductor plate has been designed. It has the advantages of high speed, environmental protection, and a low turning radius. Differing from existing maglev vehicles, this paper proposes a new maglev vehicle utilizing six EDWs to respectively provide driving force and levitation force. This structure can keep the levitation force at a large constant value and obtain enough driving force at low rotational speeds by adjusting the motor speed. First, the structure of the electrodynamic wheel is given. The accuracy and validity of the FEM results are verified by the experiments. Moreover, based on the finite element method (FEM), the optimal structure of the EDWs is obtained with the objective of maximum levitation force. Then, the simplified electromagnetic force model is obtained by using MATLAB Toolbox. Third, using a co-simulation of Simulink and Adams to design and build a 1:50 maglev vehicle model, this article studies the dynamic response characteristics of the maglev vehicle model from the perspective of dynamics and proposes a feedback control strategy by adjusting the rotational speed to control the maglev vehicle. This paper also proposes a method to realize the car's pivot steering to reduce the car's turning radius and help the drivers pass narrow road sections. This article verifies the feasibility of the maglev vehicle with six EDWs and is expected to provide a certain reference for the development of permanent magnet electrodynamic suspension vehicles. [ABSTRACT FROM AUTHOR]

Inspired by the guidance principle in the electromagnetic levitation system, a new permanent magnet electrodynamic suspension (PM EDS) structure with ferromagnetic guidance track is proposed and analyzed in this paper. Considering the lack of effective guidance ability for the PM EDS system, we adopted the ferromagnetic guidance track as being mounted under the conductor plate. The guidance principle is studied and the implementation of the guidance function is also introduced, and the finite element method (FEM) is employed and its accuracy is confirmed via the PM EDS high-speed rotating experimental platform fabricated in our laboratory. The influence of longitudinal speed on the guidance force is taken into account, which shows that the guidance performance is enhanced more obviously at low speeds. Moreover, the influence of the guidance track parameters on the guidance performance is also analyzed, including the geometric parameters, section shape, installation position and material. The equivalent small-scale PM EDS system experimental prototype is carried out to validate the effectiveness of the ferromagnetic guidance. The proposed ferromagnetic guidance structure is demonstrated to improve the guidance performance of the PM EDS system effectively, which will offer a technical reference for the practical engineering application of the PM EDS system. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) magnetic levitation (maglev) trains for designed high speed need a non-contact braking method that can produce stable and sufficient braking forces to ensure the safety of the train during emergency braking. In order to study the braking effects of permanent magnet eddy current braking (PMECB) used in HTS maglev vehicles and its effects on the levitation performance of HTS maglev vehicles, an equivalent two-dimensional simulation model of PMECB for a HTS maglev test vehicle under different working air gaps of 5 mm, 10 mm, 15 mm and 20 mm was established in Maxwell software. Then, a 6 degree of freedom dynamic model of the vehicle was established in Universal Mechanism software. In the dynamic simulation, the normal force of PMECB was not considered, and only the detent force of PMECB was taken as the excitation of the vehicle. The simulation results show that PMECBs can reduce the vehicle to relatively low speed in a few seconds. During the operation of PMECBs, the levitation height and levitation force of the maglev Dewar will be affected, and maximum variations in levitation heights and levitation forces occur on the Dewars at both ends of the vehicle. These help us to understand the braking and levitation performance of HTS maglev vehicles under the action of PMECBs and enrich the design idea of braking and levitation systems of HTS maglev vehicles equipped with PMECBs. [ABSTRACT FROM AUTHOR]

• The levitation force is measured at the highest 240 km/h. • The mathematical model of the dynamic levitation force and operating speed is established. • The dynamic levitation force is found to be elastic and recoverable. • The influence of liquid nitrogen on permanent magnet track is found and avoided in the analysis. High-temperature superconducting (HTS) pinning magnetic levitation (maglev) has garnered significant attention in high-speed maglev transportation due to its inherent self-stability, low energy consumption, and absence of mechanical friction. Ensuring the safe and stable operation of HTS pinning maglev systems necessitates a dedicated focus on the performance and stability of HTS bulks levitated above the permanent magnetic guideway (PMG). Previous research has indicated that variations in the temperature within the HTS bulk can impact the levitation performance of the system. This temperature-related phenomenon occurs when the external magnetic field applied to the HTS bulk changes. However, it is noteworthy that previous levitation force tests for HTS magnetic levitation systems have been limited to quasi-static or low-speed studies. The exploration of dynamic levitation forces, particularly at high speeds, has remained constrained due to the associated high costs. Therefore, the objective of this study is to investigate dynamic levitation forces while the HTS pinning maglev system is in motion at high speeds, utilizing a self-developed ultra-high-speed maglev test rig. Initially, the relationship between the levitation force and the vertical displacement of the HTS pinning maglev system is examined based on quasi-static experiments. Subsequently, comparative studies are conducted to measure levitation forces at varying speeds. Finally, the correlation between running speed and dynamic levitation force is discussed. The investigation reveals that the levitation force experiences only a marginal decrease as the running speed increases. At a running speed of 240 km/h, the attenuation rate of the levitation force is approximately 2.478 %, demonstrating the commendable stability of HTS pinning maglev systems. The article concludes by presenting the dynamic levitation characteristics and their attenuation trends to speed. These findings can serve as valuable references for future design and practical implementation of HTS pinning maglev systems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With the merits of self-levitation, self-stabilization, zero magnetic drag, environment-friendliness, and low energy consumption, high-temperature superconducting (HTS) maglev is regarded as one of the main technology modes for the future rail transit. For the researches on the lateral-vertical coupled dynamics of the HTS maglev, there is still a lack of lateral-vertical coupled force model that can characterize the macroscopic force between high-temperature superconductor and permanent magnet guideway (PMG). In this article, a scanning experiment of levitation force and guidance force in a selected area on the vertical plane was carried out, and the law of levitation force and guidance force changing with coordinates was studied as well. Moreover, the finite element method was used to calculate the magnetic field distribution of the Halbach-type PMG, meanwhile, the Lorentz force formula was utilized to analyze the influence law of PMG's magnetic field on the levitation force and guidance force. On the basis of this research, a 2-D force model that neglects the hysteretic between high-temperature superconductor and PMG was established. By comparing the simulation results of the model with the measured data of the experiment, it is found that both of them are in good agreement, which verifies the reliability of the proposed model. The 2-D force model is very helpful to the future research and calculation of the dynamics of the HTS maglev. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) maglev system, based on the magnetic flux pinning characteristic of non-ideal type II superconductors, can realize self-stable above permanent magnets. HTS maglev possesses the advantages of low-energy consumption, simple mechanical structure and environment-friendly, which make it an ideal high-speed transportation mode. When an HTS maglev vehicle crosses a ramp, the levitation height will fluctuate due to the rapid change of the track curve, which may affect the safety and stability of the system. In this paper, first, a levitation force model was obtained based on experimental data. Based on this model, a dynamic model of the HTS maglev vehicle-bridge coupled system was established. The dynamic response of the maglev train was simulated and analyzed when it operated through track grade change points under different track slopes, vertical curve radii and speeds. The influence of these parameters on the stability of the system was investigated, and the optimized design parameters for the vehicle and the track slope are proposed as well. This study provides references for the future engineering development of HTS maglev transportation. [ABSTRACT FROM AUTHOR]

• Dynamic characteristics and vibration of linear PMEDS are studied using test rig. • Magnetic-mechanical coupling of PMEDS is implemented for the first time. • An experiment prototype for flied test is fabricated and it is fully levitated. • A periodical simulation model for reducing calculation time is proposed. This study investigates the dynamic electromagnetic characteristics and thermo-mechanical coupling effect of the linear permanent magnet electrodynamic suspension system (PMEDS) via high-speed test rig. Besides, a physical prototype weighing 1.5 tons along with a 50-m linear copper guideway is developed and tested. Firstly, the topology structure along with fundamental operation model is introduced, followed by establishing the analytical model. Subsequently, a multi-functional test rig is utilized to experimentally determine its speed characteristics, lateral stability, and vertical vibration, while also validating the simulation and analytical models. Additionally, thermo-mechanical coupling analysis is conducted through co-simulation, experimentation and calculation to determine the dependence of temperature on the levitation and drag forces. Finally, a prototype vehicle integrated with auxiliary components, is fabricated and tested on a copper guideway. The vehicle is suspended freely via levitation force in the air above 30 mm, with tested suspension height generally aligning with dynamic simulation results. [ABSTRACT FROM AUTHOR]

A high-temperature superconducting (HTS) magnetic levitation (maglev), based on YBaCuO bulk superconductors and permanent magnet guideways, shows the potential to be applied in the future rail transportation. The maglev forces (levitation and guidance force) of the HTS maglev system, which bond the vehicle and the guideway, are the key factors of its dynamics studies. In practical operation, the HTS maglev vehicle moves in both the vertical and lateral directions, but the previous force models are in single degree of freedom. In this article, an experiment was designed to study the vertical–lateral coupled effect of the levitation and guidance force. A 2-D coupling model was proposed to fit the experimental data. Furthermore, the motion stability and the dynamical characteristics of the HTS maglev system in 2-D space were studied. The simulation results show that the vertical–lateral coupling effect in maglev forces cannot be neglected, and one direction motion can affect the motion in the other direction. It also shows that the proposed force model is suitable for HTS maglev dynamics’ calculations. [ABSTRACT FROM AUTHOR]

The high-temperature superconducting (HTS) maglev system is characterized with self-stable levitation, low energy consumption, and pollution-free operation, and it has been considered as a promising technology for implementing high-speed transport systems. But the previous studies have shown that the damping of such system is relatively low, which indicates the large-amplitude nonlinear vibration may occur easily under external disturbances and affect the long-term motion stability, operation safety, and comfort of HTS maglev in rail transit application. In order to suppress the harmful vibration, an electromagnetic shunt damper (EMSD) was designed and incorporated into the HTS maglev system. Compared with other systems which employ the EMSD to diminish the vibration, the HTS maglev system does not need to set up external devices to supply magnetic field for the damper, because the permanent magnet guideway (PMG) in this system is directly taken advantages of. The natural frequency of the damper is adjusted to a value close to that of the maglev system. In this way, the damper becomes most effective because the moving vehicle body and the circuit resonate simultaneously. The feasibility of the damper was demonstrated through systematic experiments, and the effects of different field cooling heights (FCHs) of the HTS maglev system on EMSD's performance were experimentally studied as well. Also, how the change of resistors in the EMSD circuit affects its working efficiency was preliminarily explored in this work. The results show that under the definite external disturbance, the damper can effectively attenuate the acceleration of vibration, furthermore, and it is found that the damper works better in condition of lower FCH. Within the scope of our experiments, the EMSD with a resistor in lower resistance performs better as results have shown. This investigation indicates that the vehicle will run in a more smooth and comfortable way along the track with this damper. The work is important for the further practical application of the technology. [ABSTRACT FROM AUTHOR]

The interaction between the high-temperature superconducting (HTS) bulk and permanent magnet guideway (PMG) has been a topic among the existing HTS magnetic levitation systems. Up to now, the theories about the electromagnetic and force characteristics have been relatively consummated. Here, using the finite element model by COMSOL Multiphysics 5.3a, we investigated the impact of the intrinsic and external factors on the levitation characteristics of HTS maglev systems, the application laws are concluded. Factors including the critical current density and geometric dimensions of the bulk superconductor, as well as the moving velocity, are discussed. The effects of the multiple back and forth movements are also analyzed. By comparing calculation results of the distributions of the induced current and the levitation force of the bulk superconductor, we can clearly confirm the effect laws of various factors on the electromagnetic characteristics and levitation force. These observations support the physical parameters that are difficult to be tested by experiments. And they also have a significant contribution to the experimental condition selections and optimization of the high-temperature superconducting magnetic levitation. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) bulk YBa2Cu3O7‐x (YBCO) can achieve self-stable magnetic levitation (maglev) over a permanent magnet (PM) for its inherent flux pinning effect, which has considerable potential for engineering applications. The complicated vibration response, however, is lacking in research for the nonlinearity of the interaction force between the HTS bulks and PMs. This paper mainly focuses on the subharmonic resonance of the HTS bulks YBCO levitating above the PMs in Halbach array, which are in reciprocating motion, by numerical simulations. In general, the motion of HTS bulks is approximately harmonic under limited excitation. When the amplitude and frequency of the excitation satisfy certain conditions, the dynamical system undergoes a period-double bifurcation, and then, the subharmonic resonance occurs. Moreover, the period-double bifurcation brings the jump phenomenon when the frequency of excitation increases and decreases at the double of eigenfrequency nearby. Simulations show that a suitable damping is able to reduce the vibration markedly. The subharmonic resonance region in an amplitude-frequency plane is presented in this paper finally. In a word, the subharmonic resonance would occur in an HTS maglev system under certain conditions and its prediction is numerically studied here with a nonlinear mathematics model of the levitation force. [ABSTRACT FROM AUTHOR]

In practical high-temperature superconducting (HTS) maglev systems, it was found that the levitation force of the onboard bulk superconductors may attenuate gradually under the inhomogeneous magnetic field. The corresponding phenomenon is that the levitation height will decay in the macroscopic and affects the long-term stability of the maglev vehicle. Thus, it is of great significance to study the dynamic levitation force of bulk superconductors under a varying external magnetic field and lay a foundation for the moderate and high-speed HTS maglev system application. In this paper, first, an experiment related to the dynamic levitation performance of YBCO bulks is carried out with a self-developed HTS maglev dynamic measurement system for the investigation of force attenuation. Then, a corresponding two-dimensional simulation model based on the finite element software of COMSOL Multiphysics 5.3 is built to research the dynamic levitation force of bulk superconductors moving above a nonuniform magnetic field. In the simulation, the electromagnetic properties are calculated using the H-formulation, and the moving mesh is employed to implement the relative movement between the bulk superconductors and permanent magnets. The experiment process is repeated in the simulation model, and the simulation results agree with the experimental results. [ABSTRACT FROM AUTHOR]

In order to clarify the correlations between magnetic flux and levitation force of the high-temperature superconducting (HTS) bulk, we measured the magnetic flux density on bottom and top surfaces of a bulk superconductor while vertically moving above a permanent magnet guideway (PMG). The levitation force of the bulk superconductor was measured simultaneously. In this study, the HTS bulk was moved down and up for three times between field-cooling position and working position above the PMG, followed by a relaxation measurement of 300 s at the minimum height position. During the whole processes, the magnetic flux density and levitation force of the bulk superconductor were recorded and collected by a multipoint magnetic field measurement platform and a self-developed maglev measurement system, respectively. The magnetic flux density on the bottom surface reflected the induced field in the superconductor bulk, while on the top, it reveals the penetrated magnetic flux. The results show that the magnetic flux density and levitation force of the bulk superconductor are in direct correlation from the viewpoint of inner supercurrent. In general, this work is instructive for understanding the connection of the magnetic flux density, the inner current density and the levitation behavior of HTS bulk employed in a maglev system. Meanwhile, this magnetic flux density measurement method has enriched present experimental evaluation methods of maglev system. [ABSTRACT FROM AUTHOR]

With the development of high temperature superconducting (HTS) maglev stepping in a key period of test line applications, the test and analysis of the dynamic operation parameters become more and more crucial. In this paper, the dynamic operating characteristics of single-cryostat and multicryostat levitation systems were comparatively studied on a 45-m-long permanent magnet guideway test line with different working conditions. Vibration acceleration signals of three levitation systems (a single cryostat, a bogie with two cryostats, and a car with four cryostats) were measured in the running experiments. The vibration characteristics were analyzed in both time domain and frequency domain. Results show that the multicryostat levitation system has better dynamic performance of stiffness than those of the single-cryostat system. The experimental data also indicates a positive correlation between the stability of the HTS maglev vehicle and the number of the cryostat. This work is helpful to understand the essential characteristics of HTS maglev vehicle system, and will be beneficial to the future design. [ABSTRACT FROM PUBLISHER]

The track regularity of a permanent-magnet guideway (PMG) is an important issue to ensure the riding comfort and running stability of high-temperature superconducting (HTS) maglev vehicles. Compared with defects of typical railway tracks, similar defects on PMG could affect the magnetic field at the levitation height and then influence the running performance and the riding comfort of the maglev system. In this paper, the influence of four kinds of Halbach PMG defects on magnetic field distribution was investigated by a finite-element simulation method. According to the calculation results, it is found that the sensitivity of the magnetic field inhomogeneity varies with each kind of defect. The vibration experiments found that the magnetic field inhomogeneity does bring vibration to HTS maglev vehicles. The results could provide significant references for future PMG design in the HTS maglev system. [ABSTRACT FROM AUTHOR]

Bulk high-temperature superconductors with a rectangular shape are easy to realize a compact assembly, which is promising for maglev applications. In order to find a reasonable array pattern, we have studied the levitation force of four multiseeded rectangular YBaCuO blocks with three possible arrays above two different permanent-magnet guideways (PMGs). Experimental results show that the levitation force can be improved by optimizing the array pattern of the bulk superconductors. An effective method to improve the utilization rate of the applied magnetic field is to avoid the joint air gaps between bulks located in a strong magnetic field area of the PMG. The optimal array pattern is able to enhance the levitation performance of the present superconducting maglev vehicle. [ABSTRACT FROM PUBLISHER]

• A new field cooling method is proposed to increase the suspension force of Maglev system based on YBaCuO bulks and permanent magnets. • The new proposed field cooling method can increase the vertical suspension force by 32%. • The new proposed field cooling method can increase the stability of the HTS pinning maglev system. • With the new method, the loading capacity of the lower-suspension form can almost reach the upper-suspension form. High-temperature superconducting (HTS) pinning magnetic levitation (maglev) transit, with the advantages of passive stabilization, nearly resistance free and the ability to suspend in different directions, has attracted more and more attentions. Though the USF (upper-suspension form) and SSF (side-suspension) form of HTS pinning maglev were widely studied and gradually applied in engineering, the weak loading capacity of the LSF (lower-suspension form) has been keeping it from application. In this paper, a new field cooling method is proposed to increase the suspension force of the HTS pinning maglev system in LSF. The vertical and lateral suspension force using the new proposed method was measured and analyzed by two rectangular three-seeded YBa 2 Cu 3 O 7 bulks, as well as the LSF with the original field cooling method and the USF for comparison. The result shows that, when the bulks move down in 5 mm, the vertical suspension force reaches to 207 N when the FCG (field cooling gap) is 5 mm, 70 N when the FCG is 15 mm. The experimental data suggests that the new proposed field cooling method can increase the vertical suspension force by 32%, and also increase its stability. With this new field cooling method, the loading capacity of the LSF can almost reach the USF, while the guiding capacity is far better than the USF. This paper suggests that the LSF is a potential suspension form for the HTS pinning maglev with the new proposed field cooling method. And this paper can provide insight and reference for different HTS pinning suspension form. [ABSTRACT FROM AUTHOR]

• Both the static experiment and the dynamic experiment were adopted to study the stiffness of the HTS upper maglev system. • The result shows that levitation stiffness does not have a strong regular relation with the levitation height as prediction but has a linear relation with the levitation force in the limit space above the PMG. • A systematic differential equation was proposed to describe the levitation stiffness characteristic of HTS upper Maglev. • The proposed stiffness model can provide reference for the dynamic calculations of HTS Maglev vehicle system. High temperature superconducting (HTS) magnetic levitation (maglev) train, by virtue of its passive stabilization, has the potential to become the next generation high-speed rail transit mode. For the further practical HTS maglev dynamic study and design, the levitation stiffness between the superconductors and the permanent magnet plays a significant role. Due to the nonlinear characteristics and the hysteresis phenomenon of the levitation force, the levitation stiffness is a variadic value. This varying stiffness complicates the vibration reduction design. And the violent vibrations caused by the lack of reasonable design can endanger the safety and comfort of the vehicle. In this paper, the levitation stiffness of a YBaCuO superconductor vessel levitating above a permanent magnetic guideway (PMG) in Halbach-array was measured and analyzed. First, a quasi-static experiment was designed to measure the levitation stiffness, which will be assessed during different vessel movement, separately. Subsequently, the natural frequencies of the levitation system under different working loads were measured by a series of dynamic experiments, and the levitation stiffness calculated by vibration was compared with the test result of the quasi-static experiment. Finally, a systematic differential equation was proposed to describe the levitation stiffness varying phenomena, and its dynamic characteristics were analyzed and verified by simulations as well. The result of this paper shows that the levitation stiffness does not have a strong regular relation with the levitation height as prediction but has a linear relation with the levitation force in the limit space above the PMG. And the studies about the stiffness characteristics with the proposed stiffness model in this paper can provide reference for engineering application and relative dynamic calculations. [ABSTRACT FROM AUTHOR]

The magnetic bearing is considered as one of the most prospective applications of high temperature superconductors (HTSs) which can realize stable levitation in a magnetic field generated by permanent magnet devices or coils. The exploration of this kind of HTS bearing through numerical investigation is usually made by assuming the induced current circulates only within the ab-plane and thus simplifying the actual three-dimensional problem to a two-dimensional one. In this paper, on the basis of the three-dimensional model of the HTS bulk established before, we further introduce the developed finite-element software to calculate the magnetic field generated by a magnetic rotor which is composed of permanent magnet (PM) rings and ferromagnet (FM) shims, and in this way, we can investigate the magnetic forces (radial force and axial force) of a simplified HTS bearing model, i.e., two symmetric HTS bulks and a magnetic rotor, at a three-dimensional level. The investigations performed in this paper lead to the observations: the favorable configuration to construct the HTS bearing is that the axial height of each HTS element should be equivalent to the axial heights of PM ring plus FM shim; the increase of the radial thickness of PM ring will improve both the radial force and the axial force considerably, but its margin decreases; the enhancement of critical current density of HTSs due to the decrease of operating temperature can result in a higher increase of both the radial and axial force with a lower nominal gap between the HTSs and the magnetic rotor. [ABSTRACT FROM AUTHOR]

the basic parameter in the design of high-temperature superconducting (HTS) magnet levitation (maglev) vehicle system, the levitation force data are usually obtained by experiments, so a reliable measurement method is needed to know the practical levitation force of onboard bulk superconductor. Considering in the actual operation the vehicle will experience some small vertical or lateral movements, especially during the passenger going on or off the vehicle, the usual measurement method for levitation force, in which force with gap and force relaxation are measured, cannot be able to predict the levitation force change due to the vertical or lateral movements. So a measurement method is presented regarding effects of force with gap, relaxation, vertical and lateral movements. Compared with a former measurement method, the presented method may support more reliable levitation force data for the HTS maglev vehicle design. [ABSTRACT FROM AUTHOR]

In the high-temperature superconducting (HTS) pinning magnetic levitation system, permanent magnet guideways (PMG) need to be laid along the line as an essential part, and currently the guideways are all made up of NdFeB permanent magnets containing rare earth elements. To reduce the dependence on the rare-earth materials and to reduce the cost of the guideway, a double-layer double quasi-Halbach guideway has been designed and fabricated. The design is based on the finite element simulation using Maxwell equations. PMG model is based on the magnetic remanence and relative magnetic permeability of material, and bulks model is based on the power law model. The performance of the quasi-Halbach guideway is intermediate between that of the one-polar guideway and the Halbach guideway. Under the same conditions, a group of array of quasi-Halbach guideway has fewer permanent magnets and a larger vertical maximum magnetic field than a Halbach array. In this paper, a convex double quasi-Halbach multi-peak guideway has been designed by multiplexing NdFeB and ferrite material while taking PMG structure and NdFeB consumption into account. The new guideway utilizes 35% less NdFeB than the traditional Halbach guideway. Compared with Halbach guideway, there is no decrease in levitation capability at key place and only 25% decrease of guidance capability. The concept of double-layer quasi-Halbach multi-peak guideway significantly reduce the PMG's reliance on rare earth materials and then save a large amount of system expense. • A new convex multiple-pole guideway with less NdFeB are proposed and saves 35% material cost for Maglev. • Based on the comparison of various parameters, one new convex PMG structure with multiple poles was recommended and manufactured. • The new convex PMG uses only 65% of the NdFeB of the widely used Halbach PMG and achieves the same levitation capacity with a limited reduction in guidance capacity. [ABSTRACT FROM AUTHOR]

High-temperature superconducting maglev technology has great application potential in rail transit applications due to its advantages such as passive stable levitation and green environmental protection. As one of the key components of the HTS maglev system, the Halbach-type permanent magnet guideway (PMG) enhances the magnetic field on one side of the guideway and weakens that on the other side. Optimizing the PMG, including the geometry and magnetic properties of the magnet, is an effective method to improve the levitation and guidance performance of the system. In addition, since NdFeB permanent magnets are expensive, optimizing the design of the PMG for the HTS maglev system is also an important work to reduce the application cost. In this paper, the Nelder–Mead Simplex method (NMS) in the optimization solver in COMSOL software is used to optimize the geometric parameters of the Halbach PMG according to the different objective requirements of the HTS maglev system. The optimization objectives include the maximum levitation force and guidance force under the constraint of the maximum cross-sectional area of the PMG, as well as the minimum cross-sectional area of the PMG with a minimum levitation force constraint. The results indicate that the NMS method is effective. By comparing four PMGs during the optimization process, it is found that this method can fully improve the utilization of the magnetic field by changing the geometric parameters of the Halbach PMG. This study can provide a valuable reference for the optimal design of the PMG for HTS maglev systems in the future. [ABSTRACT FROM AUTHOR]

• Design permanent magnet for high-temperature superconducting Maglev systems. • Analyze the demagnetization characteristics of guideways at high temperatures. • Choose the Halbach-type guideway with better performance for detailed optimization. High-temperature superconducting (HTS) pinning Maglev systems are advantageous due to their ability to achieve large-scale passive-stabilized levitation. Elevated temperatures can lead to a reduction in the magnetic characteristics of the permanent magnet guideway (PMG), which may pose a risk to the safe functioning of HTS Maglev trains. In order to guarantee the secure and dependable functioning of HTS Maglev trains, it is necessary to augment the high-temperature stability of the PMG. This study involves simulating the high-temperature stability of present PMGs and developing a new PMG that exhibits greater performance. Magnetic field simulation is employed to compute the demagnetization of permanent magnets (PMs) in several typical PMGs, encompassing both reversible and irreversible scenarios, in order to examine the factors contributing to demagnetization and evaluate the thermal stability of the PMGs at elevated temperatures. The grade, size, and magnetization direction of the Halbach-type PMG are subsequently optimized and compared to the original Halbach-type PMG. Following this, ideas for further optimization are provided. The optimized Halbach-type PMG reduces the overall decay ratio of the highest magnetic flux density B z by 5.77% compared to the existing Halbach-type PMG. Additionally, the irreversible decay ratio is decreased by 6.13% at 85 ℃. The levitation force decay ratio on the HTS bulks above the optimized Halbach-type PMG is decreased by 8.11% compared to the existing Halbach-type PMG. Additionally, the irreversible decay ratio is reduced by 9% at 85 ℃. This study provides valuable insights for enhancing the efficiency and performance of PMGs and HTS Maglev trains over extended periods of operation. [ABSTRACT FROM AUTHOR]

• Damping ratio is related to the amplitude and static levitation height. • Damping differs on both sides of the vibration equilibrium point. • Calculating system damping through the cross-correlation function. • Eddy current damping of conductive shell couples with the hysteresis damping. High-temperature superconducting (HTS) pinning maglev has achieved rapid development in recent decades. The levitation system of the HTS pinning maglev is mainly composed of Dewar with built-in HTS bulks and permanent magnet guideway (PMG). For a maglev transportation system, damping is important for vibration attenuation, and the inherent damping characteristics of the HTS pinning maglev system have not been evaluated clearly. In this paper, the damping characteristics of the HTS pinning maglev system are analyzed through experiments and simulations. Experiments are conducted to measure the dynamic responses of the system under free and forced vibrations. The logarithmic envelope method is used to evaluate the system damping under free vibration. The cross-correlation function is utilized to obtain the phase difference between the system vibration signal and excitation signal, and then calculate the system damping under forced vibration conditions. In addition, a two-dimensional finite element model including HTS bulks, PMG, and Dewar conductive shells is established to evaluate the damping force generated by each component during system vibrations. The additional eddy current damping of the conductive Dewar shell is considered and analyzed. Finally, from the perspective of system damping and thermal stability of HTS bulks, suggestions for selecting Dewar shell materials are proposed. [ABSTRACT FROM AUTHOR]

Superconducting pinning maglev train, with the advantages of heavy self-stable levitation and super-low resistance, is expected to become a high-speed transit in the future. With the increase in speed, the more will the irregularity of the PMG (permanent magnet guideway) affects the safety and comfort of the superconducting pinning maglev train. This paper is based on the PMG of the test line for the first high-speed superconducting pinning maglev engineering prototype train in China, to measure and study the magnetic irregularity of the PMG and its characteristics. Experiments were designed to measure the irregularity with a single Dewar maglev system, which can obtain the equivalent geometric irregularity directly acting on the maglev unit of the vehicle. Firstly, the frequency response function is developed based on previous studies, which can transform the response signal of the Dewar into the irregularity signal of the PMG. Secondly, the velocity and position are measured by image recognition of ground markers. Then, the dynamic signal of the Dewar maglev system moving along the PMG is gained and conversed into equivalent geometric irregularities by the frequency response function. Finally, an equivalent geometric irregularity PSD (power spectral density) function is formed, and it can generate the geometrically random track irregularity for vehicle dynamic simulations. The dynamic simulation result suggests that the superconducting pinning maglev train has the potential for smooth operation at high-speed under the excitation of the current PMG. The studies of this paper can help to understand the irregularity of the PMG further, and the gained PSD function can provide a general reference for the dynamic study of the superconducting pinning maglev train. [ABSTRACT FROM AUTHOR]

• After long-time heavy load, the levitation force of the YBaCuO bulks changes small. • The dynamic model of HTS maglev vehicle is established in UM software. • The dynamic response of the three vehicles are compared under the same condition. • The HTS maglev vehicle is superior to other vehicles in some dynamic parameters. • The HTS maglev vehicle's dynamic performance has potential advantages in high speed. In order to explore the potential advantages of HTS maglev vehicles, the dynamic response of HTS maglev vehicle-bridge coupling system model under different speeds and track beam spans is calculated by using Universal Mechanism (UM) software, which is further compared with two existing high-speed train systems, the high-speed EMS vehicle and wheel-rail vehicle. Before establishing the dynamic model, first a simplified mathematical model of levitation force of HTS maglev is extracted based on the experimental results of three YBCO bulks on a Halbach permanent magnet guideway (PMG). The results of simulation show that the HTS maglev vehicle can fully meet the requirements of current high-speed railway operation index on the acceleration of car body and its influence on track beam. The comparisons show that HTS maglev vehicle has some advantages over high-speed EMS vehicle and wheel-rail high-speed vehicle, especially in the acceleration of the car body and the impact on the track beam under high-speed operation. This makes a better understanding of the dynamic performance of HTS maglev vehicle, and provides an effective reference for the selection of high-speed railway system types and related indicators in the future. [ABSTRACT FROM AUTHOR]

To improve the curve negotiating ability of high-temperature superconducting (HTS) maglev system, a special structure of magnetic superelevation for double-pole Halbach permanent magnet guideway (PMG) was designed. The most significant feature of this design is the asymmetrical PMG that forms a slanting magnetic field without affecting the smoothness of the PMG surface. When HTS maglev vehicle runs through curves with magnetic superelevation, the vehicle will slant due to asymmetry in magnetic field and the flux-pinning effect of onboard HTS bulks. At the same time, one component of the levitation force provides a part of the centripetal force that reduces lateral acceleration of the vehicle and thus enhances its curve negotiating ability. Furthermore, the slant angle of magnetic superelevation can be adjusted by changing the materials and the thickness of the added permanent magnets. This magnetic superelevation method, together with orographic uplift, can be applied to different requirements of PMG designs. Besides, the applicability of this method would benefit future development of high-speed HTS maglev system. [ABSTRACT FROM AUTHOR]

In order to promote the performance of present high-temperature superconducting (HTS) Maglev systems, the interaction between applicable HTS bulk arrays and an applied Halbach permanent magnet guideway (PMG) was investigated. Ten rectangular multi-seeded YBaCuO bulks were used to find an optimal arrangement for maximum levitation forces by combing the double-layer bulk array pattern and the c-axis direction design of HTS bulks. The studies were implemented in both zero-field-cooling and field-cooling conditions. The experimental results indicate that the present levitation force can be improved remarkably by optimizing the bulk array above the PMG. Compared with single-layer bulk array, Maglev performance can be improved significantly by simply adopting a double-layer bulk array. In addition, by setting the c -axis direction of HTS bulks parallel or perpendicular to the PMG field, we can obtain large levitation force or guidance force, respectively. In the optimization process, the width ratio between the HTS bulk array and the PMG is also an important factor; by designing the bulk array to cover the entire PMG width, we can improve the utilization of the applied magnetic field. Finally, an optimal bulk array pattern was recommended by taking the levitation performance and economic cost into consideration. The experimental data will be used as reference for designing the new HTS Maglev system. [ABSTRACT FROM AUTHOR]

In order to enhance the guidance force, adding the high-temperature superconducting (HTS) bulks and permanent magnets in lateral direction is the simplest way especially in curve negotiation situations. However, as the core component of maglev system, permanent magnet guideway (PMG) consists of a huge amount of NdFeB magnets along the operation line. Hence, it means a huge construction cost to add the magnets in lateral direction. To help solving this issue, this paper discusses a PMG improvement methodology based on the widely-used two-pole Halbach PMG. This proposed novel PMG can enhance the guidance force by only adding air intervals between neighbor magnets and the flux-concentration irons and raising the onboard HTS bulks' width accordingly. Firstly, a 2D electromagnetic theoretical model of the HTS bulk-PMG maglev system was built in the COMSOL Multiphysics. Then, under the different external magnetic fields of the PMGs with different air intervals, levitation and guidance performances of the typical onboard HTS bulk array at typical working conditions were discussed. The results showed that, with the suitable HTS bulks' width, the guidance force can increase with the intervals increasing in a range. And the HTS maglev system adopting this idea can achieve a guidance force growth of about 41%. This PMG idea is appropriate for curve negotiation situations because of its higher ratio of the guidance force to the levitation force, without changing the basic magnetic circuit and the magnet block number of the previous linear PMG. • An efficient permanent magnet guideway (PMG) improvement idea for curve negotiation was proposed. • The PMGs with different parameters were compared in force performances, and one PMG structure was recommended. • Both the guidance force and the ratio of the guidance force to the levitation force were raised significantly by the new PMG. [ABSTRACT FROM AUTHOR]

• A more precise HTS vehicle / track coupling model is established by adding a flexible permanent magnet track (PMT) to the HTS vehicle / track coupling system. • The theoretically infinitely long, discrete-supported PMT is abstracted as a finite-length, simply-supported Euler beam at both ends, and the correctness of the model is verified by the finite element method. • The force between the dewar and the PMT is considered as a uniformly distributed load, which is consistent with the actual situation. • The effects of different system parameters (e.g. track support spacing, stiffness values of elastic supports, etc.) on the vehicle dynamics were investigated. • Considering the stability of vehicle operation and the response of flexible track, a reasonable design of PMT system is given. High-Temperature Superconducting (HTS) Maglev has the potential to run at high speed with the advantages of stability. As a kind of track transportation vehicle, the performance of vehicle-track coupled vibration will affect the comfort and safety of vehicle operation. In this paper, the track structure is analysed and designed based on the dynamic response of vehicle-track coupling. The model of long pillow embedded ballastless track is used to simulate the discrete permanent magnet track supported by the fastener and elastic rubber pad under the fastener. Through the calculation of the coupling system of HTS maglev train, the vehicle dynamic performance under different fastener stiffness, different fastener distance and different speed is obtained. The dynamic performance of the vehicle is quantitatively evaluated by the maximum acceleration of the car body, fluctuation of suspension gap and the running stability of the vehicle. The vibration responses of vehicles and tracks under different working conditions are discussed, and reasonable design suggestions are given. [ABSTRACT FROM AUTHOR]