Suyu Wang

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.

An Update High-Temperature Superconducting Maglev Measurement System

An update high temperature superconducting Maglev measurement system (SCML-02) was successfully developed. The system includes liquid nitrogen vessel, cylinder permanent magnet (PM) or PM guideway (PMG), data collection and processing, mechanical drive and autocontrol. The liquid nitrogen vessel with high temperature superconductors (HTSCs) can be placed above or under the PM. This measurement system has other characteristics: high measurement precision, instant measurement at movement of the measured HTSCs specimen, synchronous measurement of levitation and guidance, measurement in three dimensions at one time, relaxation measurement of both levitation and guidance force, and so on. In order to calibrate measurement precision and to verify special function of SCML-02, two cylinder PMs are used, which have the same scale and technical specification. The Maglev properties of HTSCs YBCO bulk are measured on the basis of the calibration results of SCML-02. The levitation forces of single YBCO bulk and of seven YBCO bulks above PMG are measured by SCML-02. All functions are validated experimentally. The main specification of the measurement system is: position precision plusmn 0.05 mm; vertical force precision 2%c; horizontal force precision 1%c. The force measurement precision has achieved 0.02 N

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.

Levitation force of a YBaCuO bulk high temperature superconductor over a NdFeB guideway

One of the prospective applications of YBaCuO bulk high temperature superconductors (HTS) is for superconducting magnetic levitation (Maglev) vehicles. The levitation force of a single permanent magnet over a single superconducting YBaCuO bulk has been researched, but this is not enough for practical Maglev vehicles. In this paper, properties of the levitation force of a YBaCuO bulk HTS over a NdFeB guideway are investigated. The magnetic field at the guideway surface is up to 1.2 T. During the experiment, bulk YBaCuO is placed in a columnar liquid nitrogen vessel, whose bottom thickness is only 3.5 mm, and it is over the guideway. The YBaCuO is cooled in a zero magnetic field with liquid nitrogen and can move up and down at different velocities. The measurement process is fully controlled by a computer. In this case, there is a 103.4 N levitation force at a 5 mm gap between the YBaCuO (diameter=30 mm, thickness=14 mm) sample and the NdFeB guideway. In addition, the authors compare the levitation force over the NdFeB guideway with that over a single cylindrical NdFeB permanent magnet.

Method to reduce levitation force decay of the bulk HTSC above the NdFeB guideway due to lateral movement

A magnetic levitation vehicle using bulk high-Tc superconductors (HTSC) is considered as a promising transportation type thanks to its lateral inherent stability, but previous studies have found that the levitation force (LF) decays due to lateral movement. In this paper, a pre-load method is presented to reduce the LF decay, and the experimental results indicate that this method is very applicable in supressing this decay in spite of the applied field and material property of the bulk HTSC, and this effect can be ascribed to the reduction of the hysteresis loss in the bulk HTSC, i.e. more trapped magnetic flux after the pre-load case. In the end, experimental results indicate that the Halbach PMG has an advantage to reduce the cost of the PMG, but its rate of LF decay is also larger due to lateral movement

Free Vibration of the High Temperature Superconducting Maglev Vehicle Model

Free vibration of the high temperature superconducting (HTS) Maglev vehicle model has been investigated after an impulse force over the permanent magnet guideway. The impulse force was used to simulate the external disturbances on the HTS Maglev vehicle so as to study its vibration characteristics. In the experiments, the free vibration curves of time dependence of acceleration and frequency dependence of displacement were measured. It was found that the free vibration curves were some damped free vibration curves which seemed to decrease exponentially. Applying the impulse response curves to the dynamic equation of the HTS Maglev vehicle model, the stiffness and the damping coefficient were evaluated. The relationships between field cooling height (FCH) and the stiffness and damping coefficient were investigated. A 30 mm FCH has been proposed for the good dynamic stiffness and damping coefficient so that the unnecessary vibration of the HTS Maglev vehicle model can be eliminated automatically. The dynamic results are helpful to the further design of the HTS Maglev transport system for high-speed application.

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.

Guidance force in an infinitely long superconductor and permanent magnetic guideway system

Guidance force is calculated when a high-temperature superconductor moves laterally on a permanent magnetic guideway. Both the superconductor and the guideway are infinitely long. The dependence of guidance performance upon both geometrical parameters, such as the shape of the superconductor and the guideway, and intrinsic parameters, such as critical current density of the superconductor and uniform magnetization of the guideway, are studied. The results may be helpful to the design and optimization of the superconducting magnetically levitated train system.

Levitation force of multi-block YBaCuO bulk high temperature superconductors

Experimental results of levitation force of multi-block YBaCuO hulk HTSs over a NdFeB guideway are presented. The magnetic field in the center of the surface of the NdFeB permanent magnet guideway is up to 1.2 T and still 0.4 T at the position of 20 mm above it. Several YBaCuO bulk samples are fixed in a columnar liquid nitrogen vessel with a thin bottom (3.5 mm). The experimental results show that the levitation force is quite different for various combinations of YBaCuO bulks. The otal combination magnetic levitation force of seven blocks of YBaCuO bulk superconductors is 264.1 N when the gap between the YBaCuO HTS and the NdFeB guideway is 10 mm, and levitation force is 167.5 N at 20 mm. Levitation force is even 106.2 N at 30 mm. The optimization of the levitation force of multi-block YBaCuO bulk superconductors is discussed after the authors analyze the experimental data.

Performance Advances of HTS Maglev Vehicle System in Three Essential Aspects

In order to put the practice of high temperature superconducting (HTS) Maglev vehicle technology into peoples life, the interaction between high temperature superconductor (HTSC) and permanent magnet guideway (PMG) as the basic model of HTS Maglev vehicle was carefully investigated and enhanced from three essential aspects, i.e., bulk HTSC material, PMG field and bulk HTSC magnetization. The maglev experiments were performed with three kinds of bulk HTSC materials, two kinds of PMGs and two kinds of magnetization methods. It is found that three aspects are all very effective to improve the levitation capability and lateral stability. With better bulk material, more reasonable PMG configuration and magnetization method, the performance of HTS Maglev vehicle system will be greatly advanced and closer to an economical and practical level.