Physica C 378 381 (2002) 809 814 www.elsevier.com/locate/physc The first man-loading high temperature superconducting Maglev test vehicle in the world Jiasu Wang a, *, Suyu Wang a, Youwen Zeng b, Haiyu Huang c, Fang Luo d, Zhipei Xu b, Qixue Tang a, Guobin Lin d, Cuifang Zhang c, Zhongyou Ren a, Guomin Zhao d, Degui Zhu e, Shaohua Wang b, He Jiang a, Min Zhu a, Changyan Deng c, Pengfei Hu d, Chaoyong Li d, Fang Liu b, Jisan Lian d, Xiaorong Wang a, Lianghui Wang e, Xuming Shen a, Xiaogang Dong a a Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, Sichuan 610031, China b College of Mechanical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China c College of Computer and Communication Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China d College of Electric Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China e Department of Materials, Southwest Jiaotong University, Chengdu, Sichuan 610031, China Received 27 September 2001; accepted 20 December 2001 Abstract 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. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 85.25.Ly Keywords: YBaCuO bulk superconductors; HTS Maglev equipment on board; HTS Maglev vehicle 1. Introduction * Corresponding author. Tel./fax: +86-28-7600787. E-mail addresses: jswang@home.swjtu.edu.cn, asclab@ home.swjtu.edu.cn (J. Wang). The principal defect of the TR-07 electromagnetic levitation system using normal electromagnets 0921-4534/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII: S0921-4534(02)01548-4
810 J. Wang et al. / Physica C 378 381 (2002) 809 814 in Germany is the small gap (8 mm) between the vehicle and the guideway. The electrodynamic levitation Maglev system using low T c superconducting magnets in Japan has a large gap (100 mm), but the operating temperature is very low and it can not levitate in a static state. Melt-textured YBaCuO bulk has high critical current density and critical magnetic flux. Both a large levitation force and a stable equilibrium are obtained. The high temperature superconductors (HTS) YBaCuO bulk may be cooled using liquid nitrogen. This makes HTS particularly attractive for the applications in magnetic bearings, rotating electrical machines, flywheel energy storage devices, and magnetic levitation. One of the prospective applications of YBaCuO bulk superconductors is superconducting Maglev vehicle [1 9]. The Maglev concept using HTS bulk has been demonstrated by the Beijing small model [5,6]. Thus far, there is no report about man-loading HTS Maglev vehicle. With the improvement of the preparation technology of YBaCuO bulk, a melt-textured YBaCuO bulk has high critical current density and critical magnetic flux density. A magnetic levitation measurement system of HTS is developed. The levitation properties of YBaCuO bulk superconductors over a guideway composed of NdFeB permanent magnets are investigated by the measurement system [10,11]. The feasibility of HTS Maglev vehicle is confirmed experimentally. According to those research results, the high temperature superconducting Maglev test vehicle is designed. Here, the first man-loading HTS Maglev test vehicle in the world is reported. This vehicle was first tested successfully on December 31, 2000 in the Southwest Jiaotong University, China. The vehicle is 3.5 m long, 1.2 m wide, and 0.8 m high. When five people stand on the vehicle and the total weight is 530 kg, the net levitation gap is more than 20 mm. Heretofore about 17,000 passengers took the vehicle, and it operates very well from beginning to now. The whole vehicle system includes three parts, vehicle body, guideway and controlling system. The onboard superconductors are melt-textured YBaCuO bulks, all of which are made in China and provided by the Beijing General Research Institute of Non-ferrous Metals and the Northwest Research Institute of Non-ferrous Metals. 2. Experiment research equipment We have developed a HTS Maglev measurement system [12] in order to design high performance HTS Maglev vehicle. The properties of the levitation force of HTS YBaCuO bulks over the NdFeB guideway are investigated with this measurement system. The system includes a liquid nitrogen vessel, one or two permanent magnet guideway, data collection and processing, precision mechanical drive and automatic control. The liquid nitrogen vessel with HTS is put on the permanent magnet guideway. The bottom wall of the vessel is a thickness of 3 mm. The magnetic field of the guideway can be increased by the application of the flux concentration scheme of the magnet arrangement. The permanent magnet guideway is 920 mm long, and its concentrating magnetic flux density is up to 1.2 T. The specifications of the measurement system are: 200 mm vertical maximal displacement, 0.1 mm precision, 2000 N vertical maximal support force, 0.2% precision; 100 mm guideway horizontal maximal displacement, 0.1 mm precision, 1000 N horizontal maximal support force, 0.1% precision. The trapping flux of HTS and the magnetic induction of the guideway can be measured in a scanning range of 100 mm 100 mm. The system can realize real time measurement of one or many superconductors. The measurement process is completely controlled by a computer. During the experiment, the YBaCuO is placed in a columnar liquid nitrogen vessel [13], whose bottom thickness is only 3 mm, and it is over the guideway. The YBaCuO is cooled by liquid nitrogen in a zero magnetic field, which can move up and down at different velocities. The guidance force, stable equilibrium force along lateral direction of the guideway, is measured at the condition of different trapped flux. The drive device of three dimensions can make scanning measurement of the magnetic field of guideway and high T c superconducting permanent magnets.
3. Levitation force measurement of HTS over guideway J. Wang et al. / Physica C 378 381 (2002) 809 814 811 Firstly, the levitation force of a high T c YBaCuO bulk superconductor over the NdFeB guideway is measured by above measurement equipment. Second, many YBaCuO bulks are put in a rectangleshape liquid nitrogen vessel, then its levitation force over the guideway is measured. Finally, the levitation force of two rectangle-shape liquid nitrogen vessel over two parallel guideway is measured. All the superconductors are melt-textured YBaCuO bulks. These sample is a diameter of 30 mm and a thickness of 14 18 mm. The YBaCuO is cooled in a zero magnetic field with liquid nitrogen. Magnetic levitation forces are measured when the liquid nitrogen vessel is moving up and down at different velocities. Fig. 1 shows the measuring results of the levitation forces of a single rectangle-shape liquid nitrogen vessel over the NdFeB guideway (surface magnetic flux density is 1.2 T), and 43 pieces of YBaCuO are Fig. 2. The total levitation force of eight rectangle-shape liquid nitrogen vessels over the guideway. included in the vessel. Fig. 2 shows the total levitation forces of eight liquid nitrogen vessels over the NdFeB guideway. Fig. 1 shows the levitation force of single rectangle-shape liquid nitrogen vessel is 1055 N at the levitation gap (between Fig. 1. The levitation force of a single rectangle-shape liquid nitrogen vessel over the guideway.
812 J. Wang et al. / Physica C 378 381 (2002) 809 814 guideway face and superconductors) of 15 mm, and the levitation force is 1362 N at the levitation gap of 8 mm. In addition, the levitation force is up to 1823 N at the levitation gap of 7 mm in another experiment. Fig. 2 shows the total levitation force of eight liquid nitrogen vessels over the NdFeB guideway is 9000 N at the levitation gap of 15 mm and 11,000 N at the levitation gap of 10 mm, respectively. The total levitation force of eight liquid nitrogen vessels over the NdFeB guideway is 8000 N at the net levitation gap (deduct 3 mm bottom thickness of liquid nitrogen vessel) of 15 mm and 10,500 N at the net levitation gap of 8 mm, respectively. These experiment results are very necessary for the design of the superconducting Maglev vehicle system in which bulk superconductors is placed in the vehicle and guideway is composed of permanent magnets. Fig. 3. The cross-section of a track. (1) Iron plate; (2) permanent magnet (NdFeB); (3) base of stainless steel. 4. Maglev system design It is well known that melt-texture YBaCuO bulks can generate large levitation force in vertical direction and lateral force in horizontal direction in an applied magnetic field. The levitation force is directly proportional to the applied magnetic field gradient. The shortcoming of the electrical magnets is both complex controlling and high electric energy consuming. If the applied magnetic field is provided by the normal permanent magnet (NPM), a larger levitation force between HTS and applied magnetic field can be achieved. Both magnetic field intensity and magnetic field gradient of the guideway can be increased by the application of the flux concentration scheme of the magnet arrangement. The guideway consists of two parallel tracks, each of them 15.5 m long. The guideway is composed of NPMs, iron plate and stainless steel plate. Fig. 3 shows the cross-section of a track. The magnetic field of a single permanent magnet is about 0.45 T, and the surface concentrating magnetic flux density of the guideway is up to 1.2 T. The transverse distribution of magnetic field of a track is shown in Fig. 4. From Fig. 4, the magnetic Fig. 4. Transverse distribution of magnetic field of a track. field of the center of the guideway is stronger than any other position, and decrease fast with the increasing of the gap from the surface of the guideway. Fig. 5 shows the distribution of magnetic field of a track along the vertical direction. The larger the gradient of the magnetic field, the larger the levitation force. However, the lateral force is dependent on the trapped flux in the superconductors. The stronger the trapped flux, the larger the lateral force. Just the levitation force between the superconductors and permanent magnets makes the vehicle levitate, and the guidance force keeps the stability of the vehicle in the lateral direction. In order to obtain larger levitation force and lateral force, superconductors must be cooled in an appropriate applied magnetic field.
J. Wang et al. / Physica C 378 381 (2002) 809 814 813 5. System test results Fig. 5. Distribution of magnetic field of a track along the vertical direction. The onboard HTS Maglev system, superconductors and cryogenic equipment, is fixed to both sides in the vehicle body. The cryogenic system consists of eight rectangle-shape liquid nitrogen vessels. Each one is a vessel with 550 mm long, 150 mm wide and 160 mm high; the bottom wall thickness is only 3 mm. The superconductors are fixed on the bottom of rectangle-shape liquid nitrogen vessels. The superconductors are cylinders with 30 mm in diameter and 18 14 mm in thickness. There are 43 pieces of superconductors in each rectangle-shape liquid nitrogen vessel. The vehicle is driven by a linear motor and is controlled by a ground controlling system. There is no controlling device in the vehicle. The controlling system only control linear motor drive system, and levitation and guidance system do not need control. The stator of the linear motor is positioned between the two tracks, and the rotor, a block of inducing plate, is attached on the bottom of the vehicle. The whole stator is 15.5 m in length, separated into six segments, and each segment is provided electric power separately. It needs no electric power in the whole vehicle system, except for the stator of the linear motor. When the stator is provided electric power, it will produce a traveling-wave magnetic field. Under the interaction of the traveling-wave magnetic and the inducing plate, an electromagnetic force will be generated, driving the vehicle. The first man-loading HTS Maglev vehicle in the world was tested successfully at 2:26 pm, December 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Firstly, the vehicle body is lifted by a liquid pressure elevator equipment till the bottom of liquid nitrogen vessels are 75 mm away from the surface of guideway, then superconductors are cooled with liquid nitrogen. When superconductors transit to superconducting state, the vehicle body is descends by the same elevator equipment. The HTS Maglev provides inherent stable forces either in the levitation or in the guidance direction. When the gap between the bottom of liquid nitrogen vessels and guideway face is about 35 mm, the vehicle body with 220 kg weight is suspended over the guideway. The function of suspension is separated from the function of propulsion. Under the driving of the linear motor, the vehicle can stably run forwards and backwards. The vehicle is 3.5 m long, 1.2 m wide, and 0.8 m high. After the vessel is filled with liquid nitrogen, the vehicle can continuously run for about 6 h. When five people stand on it and the total weight is 530 kg, the net levitation gap is more than 20 mm. Fig. 6 shows the first Maglev test of the vehicle body. When the five people get off it, the levitation height is only 33 mm, not 35 mm. It Fig. 6. The first Maglev test of the vehicle body.
814 J. Wang et al. / Physica C 378 381 (2002) 809 814 is well known that this result from the hysteresis effect of superconductors. Heretofore about 17,000 passengers took the vehicle, and it operates very well from beginning to now. 6. Conclusion The feasibility of the man-loading HTS Maglev vehicle system is verified with theory and experiment. First man-loading HTS Maglev test vehicle in the world is developed. This vehicle is 3.5 m long, 1.2 m wide, 0.8 m high (with shell). After the vessel is filled with liquid nitrogen, the vehicle can continuously run for about 6 h. When five people stand on it and the total weight is 530 kg, the net levitation gap is more than 20 mm. Both reliability and stability of this vehicle system are demonstrated by longer time operation. Heretofore about 17,000 passengers took the vehicle, and it operates very well from beginning to now. Acknowledgements Because there are many people participating the project, and they cannot be listed one by one, the authors would like to thank all the persons who contribute to the project. This work was supported by the High Technology Research and Development project in China (National 863 project in China). References [1] H. Weh, H. Pahl, H. Hupe, A. Steingrover, H. May, Proceedings Maglev 95 Fourteenth International conference on Magnetically Levitated Systems, 1995, pp. 217 222. [2] J. Wang, S. Wang, J. Lian, Cryogenics and Superconductivity 25 (1) (1997) 17 (in Chinese). [3] H. Weh, in: L.Z. Lin, G.L. Shen, L.G. Yan (Eds.), Proceeding of Fifteenth International Conference on Magnet Technology, Beijing, 1998, pp. 833 838. [4] S.Y. Wang, J.S. Wang, J.S. Lian, in: L.Z. Lin, G.L. Shen, L.G. Yan (Eds.), Proceeding of Fifteenth International Conference on Magnet Technology, Beijing, 1998, pp. 767 769. [5] Y. Zhang, S.G. Xu, in: L.Z. Lin, G.L. Shen, L.G. Yan (Eds.), Proceeding of Fifteenth International Conference on Magnet Technology, Beijing, 1998, pp. 763 766. [6] J.R. Wang, P.X. Zhang, L. Zhou, M.Z. Wu, W. Gawalek, P. Gornert, H. Weh, in: 15th International Conference on Magnet Technology, Beijing, October 20 24, 1997. [7] H. Fujimoto, H. Kamijo, T. Higuchi, Y. Nakamura, K. Nagashima,, M. Murakami, S.I. Yoo, IEEE Transactions on Applied Superconductivity 9 (2) (1999) 301. [8] J.S. Wang et al., IEEE Transactions on Applied Superconductivity 9 (2) (1999) 904. [9] S.Y. Wang, J.S. Wang, Cryogenics and Superconductivity 27 (4) (1999) 8 (in Chinese). [10] J. Wang, S. Wang, Z. Ren, M. Zhu, H. Jiang, Q. Tang, IEEE Transactions on Applied Superconductivity 11 (1) (2001) 1801. [11] S. Wang, J. Wang, Z. Ren, H. Jiang, M. Zhu, Q. Tang, IEEE Transactions on Applied Superconductivity 11 (1) (2001) 1808. [12] J. Wang et al., High Technology Letters 10 (8) (2000) 55 (in Chinese). [13] S.Y. Wang, J.S. Wang, Cryogenics and Superconductivity 27 (3) (1999) 1 (in Chinese).