High Temperature Superconducting Maglev Test Research Articles

Simulation of the Braking Effects of Permanent Magnet Eddy Current Brake and Its Effects on Levitation Characteristics of HTS Maglev Vehicles

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.

Study on Flux-Pinned Load Characteristics of High Temperature Superconducting Maglev Vehicle

With the distinctive pinned effects, the high temperature superconducting magnetic levitation vehicle is characterized by its high-performance self-stability, strong anti-interference ability and non-contact features, which are worthy of being studied in detail. In this paper, the high temperature superconducting maglev test platform in Southwest Jiaotong University was utilized to study the flux-pinned force. The calibration of vertical and lateral load characteristic curve under corresponding quasi-static conditions were conducted firstly, then it was transformed through polynomial fitting. In addition, the variation law of flux-pinned force under straight and curved tracks at different running speeds of maglev vehicle was attained based on the experiment.

A Manned Hybrid Maglev Vehicle Applying Permanent Magnetic Levitation (PML) and Superconducting Magnetic Levitation (SML)

To enhance maglev competitiveness in passive stability and simple structure, a manned hybrid maglev vehicle applying permanent magnetic levitation (PML) and superconducting magnetic levitation (SML) was developed. The vehicle is mainly composed of a maglev frame, a PML part, and an SML part. The maglev frame was employed to connect the PML and SML parts. Based on the magnetic rail of our high temperature superconducting maglev test line of the “Super-Maglev,” the onboard levitation components are bespoke to match the magnetic rails. The PML part is assembled to the maglev frame by vertical linear sliders, and is able to move freely in the vertical direction for appropriate heavy load. The driving method is linear induction motor whose primaries are installed between two rails, interacting with the induction plate mounted on the SML part. The rated load is designed as 375 kg and achieved for one passenger at 15 mm field cooling height. Measurements of its mechanical property were performed under static loads. Results display that the manned hybrid maglev vehicle possesses good advantages of load ability and passive stability at the same time. The work explores a new feasible combination of the PML and the SML for maglev applications.

A High-Temperature Superconducting Maglev Ring Test Line Developed in Chengdu, China

A 45-m-long high-temperature superconducting (HTS) Maglev ring test line, named “Super-Maglev,” has been successfully developed in Chengdu, China, in February 2013, 12 years after the birth of the first man-loading HTS Maglev test vehicle. The Maglev vehicle (2.2 m in length, 1.1 m in width) is designed for one passenger with a levitation height of 10–20 mm; the permanent-magnet guideway (PMG) (45 m in length, 0.77 m of track gauge) is a racetrack shape with a curve radius of 6 m; the driving is accomplished by a linear induction motor with a maximum running speed of 50 km/h. The linear motor is composed of four submotors installed at one straight section in the middle of the double PMGs, and the total length is 3 m. This second-generation HTS Maglev vehicle system is highlighted by the cost-performance and the wireless multiparameter onboard monitoring function. The current same-level load capability has been achieved over a small-section low-cost PMG whose cross-sectional area is only 3000 mm 2 . On the vehicle, parameters of levitation weight, levitation height, running speed, acceleration, lateral offset, online position, and total running distance of the vehicle are real-time monitored and displayed on the onboard tablet computer. The system component and test data are reported in detail in this paper.

Trapped Flux and Levitation Properties of Multiseeded YBCO Bulks for HTS Magnetic Device Applications—Part II: Practical and Achievable Performance

After clarifying the essential characteristics of the multiseeded YBCO bulk in the previous work, that is, the existence of strongly connected or coupled grain boundaries between two grains by means of intergrain super current with a big flowing loop size, this paper proceeds to report its achievable performance in actual excitation conditions by working as trapped-field magnets or levitation devices. Besides evaluation of the trapped-flux characteristics by two most popular excitation methods, namely, static field-cooling magnetization (FCM) and pulsed-field magnetization in liquid nitrogen (LN2), the trapped-flux capability at lower temperatures up to 30 K, an interesting temperature for present superconducting machine applications, is also reported. From LN2 temperature to 30 K, the trapped flux with over six times improvement from 0.64 to 3.91 T was observed by FCM, at the same time along with a much decreased relaxation rate from 13.7% to 0.9% in 1-h measurements. In the aspect of levitation applications, the magnetic force density (both levitation force and guidance force, two most important performance parameters for maglev) above a permanent magnet guideway with Halbach style is measured and found to be able to promote the loading and stability performance of the first high-temperature superconducting maglev test vehicle simultaneously. As the multiseeding technique of the top-seeded melt-growth process has provided a promising way to fabricate bulk superconductors with large size, time saving and cost reduction, the presented trapped-flux and magnetic force results may help to comprehend, refer, and finally make better use of the multiseeded bulks in the large-scale superconducting magnetic devices.

Recent Development of High Temperature Superconducting Maglev System in China

After the first man-loading high temperature superconducting (HTS) Maglev demonstration had been tested successfully years ago, its future application attracts more and more researchers and engineers. This paper reviews the recent development of HTS Maglev system in China. In the past seven years, quasi-static forces, dynamic characteristics and running performances have been studied by three self-developed HTS maglev measurement systems and 11-ch vibration measurement apparatus. Some practical problems are considered in details for further engineering application of HTS Maglev train, such as running along the forward direction with inhomogeneous magnetic field, construction cost estimation, propulsion optimization, and so on. On the other hand, a systematic method is introduced to analyze or optimize the force interaction between bulk high temperature superconductor and permanent magnetic guideway. Primary running parameters and data are obtained for the safety design of future HTS Maglev system. Furthermore, a low-mid speed HTS Maglev test line is blueprinted with a maximum speed of 100 km/h, which will be the first step of practical HTS Maglev engineering application.

Dynamic Force Properties of a High Temperature Superconducting Maglev Test Vehicle

In order to investigate the feasible application of a high-T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> superconducting (HTS) levitation system to a maglev train or a space vehicle launcher, we construct a demonstration maglev test vehicle consisting of two linear permanent magnets (PM) guideways and a test levitator with multi-block melt-processed YBaCuO superconductors. By using a vibration testing technique, we measure the dynamic force properties of the test vehicle in different field cooling (FC) and loading conditions. In both vertical and lateral vibration directions, resonance frequencies and related magnetic stiffness show large dependence on the FC height (FCH) and the load weight. The resonance frequencies increase as the FCH decreases or the load weight is reduced. The magnetic stiffness is also increased by using the low FCH or adding the load weight. It is shown that the dynamic properties of the HTS levitation system are closely related to the flux history in superconductors and the motion process of the system. Finally a low FC scheme and a preloading method are proposed to improve the stability of the HTS maglev vehicle.

Superconducting bulk magnet for maglev vehicle: Stable levitation performance above permanent magnet guideway

High-temperature superconducting (HTS) maglev vehicle is well known as one of the most potential applications of bulk high-temperature superconductors (HTSCs) in transported levitation system. Many efforts have promoted the practice of the HTS maglev vehicle in people's life by enhancing the load capability and stability. Besides improving the material performance of bulk HTSC and optimizing permanent magnet guideway (PMG), magnetization method of bulk HTSC is also very effective for more stable levitation. Up to now, applied onboard bulk HTSCs are directly magnetized by field cooling above the PMG for the present HTS maglev test vehicles or prototypes in China, Germany, Russia, Brazil, and Japan. By the direct-field-cooling-magnetization (DFCM) over PMG, maglev performances of the bulk HTSCs are mainly depended on the PMG's magnetic field. However, introducing HTS bulk magnet into the HTS maglev system breaks this dependence, which is magnetized by other non-PMG magnetic field. The feasibility of this HTS bulk magnet for maglev vehicle is investigated in the paper. The HTS bulk magnet is field-cooling magnetized by a Field Control Electromagnets Workbench (FCEW), which produces a constant magnetic field up to 1 T. The levitation and guidance forces of the HTS bulk magnet over PMG with different trapped flux at 15 mm working height (WH) were measured and compared with that by DFCM in the same applied PMG magnetic field at optimal field-cooling height (FCH) 30 mm, WH 15 mm. It is found that HTS bulk magnet can also realize a stable levitation above PMG. The trapped flux of HTS bulk magnet is easily controllable by the charging current of FCEW, which implies the maglev performances of HTS bulk magnet above PMG will be adjustable according to the practical requirement. The more trapped flux HTS bulk magnet will lead to bigger guidance force and smaller repulsion levitation force above PMG. In the case of saturated trapped flux for experimental HTS bulk magnet, it is not effective to improve its maglev performances by increasing of charging magnetic field, when the guidance force at WH 15 mm is 5.7 times larger than that by DFCM of FCH 30 mm. So introducing HTS bulk magnet into the present maglev system is feasible and more controllable to realize stable levitation above applied PMG, which is an important alternative for the present HTS maglev vehicle.

Stability of the Maglev Vehicle Model Using Bulk High Tc Superconductors at Low Speed

Based on the study of static properties of the high temperature superconducting (HTS) Maglev vehicle, the dynamic characteristics and stability are investigated in the paper. A Maglev vehicle model using 86 bulk high Tc superconductors (HTSCs) is made at 1/4 scale of the first man-loading HTS Maglev test vehicle. Dynamic characteristics of the low-speed HTS vehicle in three directions are studied by measuring vibration signals of six essential point of the vehicle model. The natural frequency is analysed. 30 mm height is suggested as a reasonable field cooling height (FCH). Lower FCH brings the operation stability of the HTS Maglev system over permanent magnetic guideway (PMG) at low speed. Dynamic stability dependence on the speed of the HTS vehicle is quite different from that of the conventional Maglev vehicle system. The effect of speed on the unsafe motions can be suppressed by decreasing FCH in the operation of the vehicle model over the PMG to a great extent.

Levitation Capability of a Bulk YBa&lt;sub&gt;2&lt;/sub&gt;Cu&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;7-x&lt;/sub&gt; with NdFeB Guideway by Two Magnetization Methods

On the requirement of high temperature superconducting (HTS) Maglev transportation application, levitation capability of bulk YBa2Cu3O7-x on the HTS Maglev test vehicle has been investigated experimentally by pulsed field magnetization (PFM) and field cooling (FC). The result showed that YBa2Cu3O7-x sample magnetized by the pulsed magnetic field behaves like a magnet in the other external field, and the magnetization direction of bulk determines its levitation force and lateral force mode (magnitude and direction) over NdFeB permanent magnetic guideway (PMG). On the other hand, static field cooling condition is with an electromagnetic field realized by Field Control Electromagnets Workbench. Two important forces of the same bulk were measured and compared with the PMG when the bulk had the same max trapped field by FC and PFM methods, and the results show the difference effects by these two magnetization methods.

Guidance forces on high temperature superconducting Maglev test vehicle

The levitation force between superconductors and permanent magnets is directly proportional to the gradient of the magnetic field over the guideway. However, the lateral guidance force is dependent on the trapped flux in the superconductors. The stronger the trapped flux, the larger the guidance force. The guidance force provides stability to the vehicle in the lateral direction. In order to obtain both larger levitation force and guidance force, superconductors must be cooled in an appropriate applied magnetic field. A man-loading high temperature superconducting (HTS) Maglev test vehicle levitating over a permanent magnet (PM) guideway, the first such in the world, was developed and equipped with guidance force measurement instrumentation and the guidance force acting on the entire vehicle are experimentally investigated. The dependence of the entire vehicle guidance force on the field cooling height (FCH) is reported. The experiment results have proved that the guidance force of the entire vehicle is large enough for the lateral stability at an FCH height of 20 mm.

The man-loading high-temperature superconducting maglev test vehicle

The first man-loading high-temperature superconducting (HTS) Maglev test vehicle in the world was successfully developed on Dec. 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Heretofore over 24 500 passengers took the vehicle, and it has been operating back and forth for about 400 km. The HTS Maglev vehicle provides inherent stability both in the vertical and lateral direction, so no control system is needed. The only control system is used for linear motor driving devices. The melt-textured YBaCuO bulk superconductors are fixed on the bottom of a liquid nitrogen vessel and cooled by liquid nitrogen. The bottom thickness of the rectangle liquid nitrogen vessel with its thin wall is only 3 mm. The onboard HTS Maglev module is placed over the guideway. The guideway consists of two parallel permanent magnetic tracks, whose concentrating magnetic field at 20 mm height above the surface is about 0.5 T. The levitation forces of 8 HTS Maglev modules were measured. The total levitation force of 8 onboard Maglev modules was 10431 N at the levitation gap of 10 mm, and 8486 N at the levitation gap of 15 mm, respectively. These results were measured on May 28, 2002.

High temperature superconducting Maglev equipment on vehicle

Onboard high temperature superconducting (HTS) Maglev equipment is a heart part of a HTS Maglev vehicle, which is composed of YBaCuO bulks and rectangle-shape liquid nitrogen vessel and used successfully in the first manned HTS Maglev test vehicle. Arrangement of YBaCuO bulks in liquid nitrogen vessel, structure of the vessel, levitation forces of a single vessel and two vessels, and total levitation force are reported. The first manned HTS Maglev test vehicle in the world has operated well more than one year after it was born on Dec. 31, 2000, and more than 23,000 passengers have taken the vehicle till now. Well operation of more than one year proves the reliability of the onboard HTS Maglev equipment.

The first man-loading high temperature superconducting Maglev test vehicle in the world

The first man-loading high temperature superconducting Maglev test vehicle in the world is reported. This vehicle was first tested successfully on December 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Heretofore over 17,000 passengers took the vehicle, and it operates very well from beginning to now. The function of suspension is separated from one of propulsion. The high temperature superconducting Maglev provides inherent stable forces both in the levitation and in the guidance direction. The vehicle is 3.5 m long, 1.2 m wide, and 0.8 m high. When five people stand on vehicle and the total weight is 530 kg, the net levitation gap is more than 20 mm. The whole vehicle system includes three parts, vehicle body, guideway and controlling system. The high temperature superconducting Maglev equipment on board is the most important for the system. The onboard superconductors are melt-textured YBaCuO bulks. The superconductors are fixed on the bottom of liquid nitrogen vessels and cooled by liquid nitrogen. The guideway consists of two parallel permanent magnetic tracks, whose surface concentrating magnetic field is up to 1.2 T. The guideway is 15.5 m long.