The rule of levitation force variation with different structure and electromagnetic parameters provides a basis for electromagnet design of electromagnetic suspension （EMS） medium and low speed maglev vehicles. In o...The rule of levitation force variation with different structure and electromagnetic parameters provides a basis for electromagnet design of electromagnetic suspension （EMS） medium and low speed maglev vehicles. In order to acquire accurate calculation results of levitation force, different calculation methods, including analytical method, 2D FEM （finite element method）, and 3D FEM, are applied to investigate the impact of various structural parameters, such as excitation current, air gap, lateral offset, and pole width, on levitation force. The analytical analysis is based on the classic mathematical model of levitation force between electromagnet and rail and performed with MATLAB. In the 2D and 3D FEMs, the numerical calculation of the levitation force is conducted with Ansoft by taking the magnetic saturation into account. In addition, the longitudinal end effect on the levitation force calculation is considered in the 3D FEM. The results show that the 3D FEM is the most accurate among the above three methods for calculating the levitation force, and the analytical method can only work for small current and/or large air gap conditions. A lateral- offset between vehicle and rail will reduce the levitation force; the levitation force descends sharply once the lateral offset exceeds the threshold, i.e., 8% of the pole width for U-shaped electromagnets. The maximum lift-to-weight ratio emerges when the pole width ratio of F type rail to electromagnet is 6：7. This may offer a reference for EMS maglev vehicle design and application.展开更多
The dipole–dipole interaction model is employed to investigate the angular dependence of the levitation and lateral forces acting on a small magnet in an anti-symmetric magnet/superconducting sphere system. Breaking ...The dipole–dipole interaction model is employed to investigate the angular dependence of the levitation and lateral forces acting on a small magnet in an anti-symmetric magnet/superconducting sphere system. Breaking the symmetry of the system enables us to study the lateral force which is important in the stability of the magnet above a superconducting sphere in the Meissner state. Under the assumption that the lateral displacement of the magnet is small compared to the physical dimensions of our proposed system, analytical expressions are obtained for the levitation and lateral forces as a function of the geometrical parameters of the superconductor as well as the height, the lateral displacement, and the orientation of the magnetic moment of the magnet. The dependence of the levitation force on the height of the levitating magnet is similar to that in the symmetric magnet/superconducting sphere system within the range of proposed lateral displacements. It is found that the levitation force is linearly dependent on the lateral displacement whereas the lateral force is independent of this displacement. A sinusoidal variation of both forces as a function of the polar and azimuthal angles specifying the orientation of the magnetic moment is observed. The relationship between the stability and the orientation of the magnetic moment is discussed for different orientations.展开更多
The influence of the width of the middle magnet in the permanent magnet guideways （PMGs） on the levitation force and the levitation height of single-domain yttrium barium copper oxide （YBCO） bulks has been investi...The influence of the width of the middle magnet in the permanent magnet guideways （PMGs） on the levitation force and the levitation height of single-domain yttrium barium copper oxide （YBCO） bulks has been investigated at 77 K under the zero field cooled （ZFC） state. It is found that the largest levitation force can be obtained in the system with the width of the middle magnet of the PMG equal to the size of the YBCO bulk when the gap between the YBCO bulk and PMG is small. Both larger levitation force and higher levitation height can be obtained in the system with the width of the middle magnet of the PMG larger than the size of the YBCO bulk. The stiffness of the levitation force between the PMG and the YBCO bulk is higher in the system with a smaller width of the middle magnet in the PMG. These results provide an effective way to control the levitation force and the levitation height for the superconducting maglev design and applications.展开更多
Top seeded infiltration and growth technique(TSIG)is an effective method for the preparation of high quality large YBa2Cu3O7-x(YBCO)bulk superconductors.In this paper,single domain YBCO bulk superconductors,with diffe...Top seeded infiltration and growth technique(TSIG)is an effective method for the preparation of high quality large YBa2Cu3O7-x(YBCO)bulk superconductors.In this paper,single domain YBCO bulk superconductors,with different Y2Ba4CuWOy(YW2411)additions,have been fabricated by TSIG process.the solid phase pellet is made of a mixture of Y2BaCuO5(Y211)+xwt%YW2411 powders,x=0,1,3,5,7,9.The growth morphology,microstructure and levitation force of the YBCO bulks have been investigated,it is found that the levitation force is increasing from 23.05 to 33.6 N with the increasing of YW2411 addition from 0 to 5wt%,and decreasing from 33.6 to 21.59 N with the increasing of YW2411 addition from 5 to 9wt%,the largest levitation force is obtained when the YW2411 content is about 5wt%.This is very important for us to fabricate high quality YBCO bulk superconductors.展开更多
The super-high speed high temperature superconductor （HTS） maglev evacuated tube transport （ETT） is a promising transport mode for the future. As a key component of the HTS maglev vehicle, the permanent magnet gui...The super-high speed high temperature superconductor （HTS） maglev evacuated tube transport （ETT） is a promising transport mode for the future. As a key component of the HTS maglev vehicle, the permanent magnet guide- ways （PMGs） with different geometrical configurations and iron yoke widths are analyzed by finite element method （FEM）. The levitation force of a single onboard HTS maglev device over the designed PMG at different field cooling heights （FCH） is measured by magnetic levitation measurement system. Based on the designed PMG and experimental results, a preliminary scheme of subterranean super-high speed HTS maglev ETT is described in this paper. The HTS maglev ETT is mainly composed of an evacuated tube, HTS maglev vehicle, PMG, propulsion system, station, emergency rescue system, etc. In addition, a subterranean tube that consists of foundation tube and vacuum airproof layer is introduced. In order to convert the stress caused by the air pressure difference between inside and outside of the vehicle, a multi-circular vehicle body is designed. The vehicle is driven by a linear motor propulsion system under the control of a ground controlling system. The scheme of long-distance super-high speed passenger transportation is accomplished by the connection of different vehicles.展开更多
The fabrication of large bulk high temperature superconducting YBCO samples was accomplished by melt-texture-growth(MTG) process with a seeding technique.The microstructure of the samples was observed by a polarizatio...The fabrication of large bulk high temperature superconducting YBCO samples was accomplished by melt-texture-growth(MTG) process with a seeding technique.The microstructure of the samples was observed by a polarization microscope.The observation shows that the samples have controlled orientation and large domains.The magnetic repulsion measurements as a function of distance were carried out.The maximum repulsion between the YBCO sample(29 mm in diameter and 10 mm thick) and a Nd-Fe-B permanent magnet with 0.5T surface magnetic field was 4.8 N/cm2 at 77K.The magnetic levitation on the samples exhibits anisotropic behaviour.展开更多
To study the influence of thickness on the magnetic properties of ReBCO(Re = Y, Gd, Sm, Nd, etc.) bulk superconductors, a single domain gadolinium barium copper oxide(GdBCO) bulk superconductor fabricated by the Re + ...To study the influence of thickness on the magnetic properties of ReBCO(Re = Y, Gd, Sm, Nd, etc.) bulk superconductors, a single domain gadolinium barium copper oxide(GdBCO) bulk superconductor fabricated by the Re + 011 top seeded infiltration growth(Re + 011 TSIG) method was continuously sliced along the bottom to obtain samples of different thickness. The levitation force and attractive force of these samples were tested at 77 K in the zero-field-cooled(ZFC)state. It is found that as the sample thickness decreases, the levitation force decreases gradually whereas the attractive force increases. This is related to the varied ability to resist the penetration of magnetic field occasioned by varying sample thickness, which are deeply revealed by combining with the characteristics of the non-ideal type-II superconductor. Further,the levitation force exhibits a trend of slow initial change followed by rapid change, which may be attributed to the growth of the sample. Measurement of the trapped field shows that a similar distribution of trapped field at the top and bottom surfaces can be achieved by removing some materials from the bottom of the bulk. These results provide a reference for meeting the actual requirements of ReBCO bulks of different thicknesses and greatly contribute to practical designs and applications.展开更多
Superconducting magnetic levitation performance, including levitation force and guidance force, is important for the application of high-temperature super- conducting maglev. Both of them are not only affected by diff...Superconducting magnetic levitation performance, including levitation force and guidance force, is important for the application of high-temperature super- conducting maglev. Both of them are not only affected by different arrays of superconductors and magnets, but also by the thickness of the iron shim between permanent magnets. In order to obtain the best levitation performance, the magnetic field distribution, levitation force, and guidance force of a new type of three magnetic hills of permanent magnet guideway with iron shim of different thicknesses （4, 6, and 8 mm） are discussed in this paper. Simulation analysis and experiment results show that the guideway with iron shim of 8 mm thickness possesses the strongest magnetic field and levitation performance when the suspension gap is larger than 10 mm. However, with the decreasing of suspension gap, the guideway with iron shim of 4 mm thickness possesses the best levitation performance. The phenomena can be attributed to the density distribution of flux and magnetization of iron shim.展开更多
YBa_(2)Cu_(3)O_(7−δ)high-temperature superconductors(HTS)exhibit remarkable passive levitation over permanent magnet guideways(PMG),but the strong nonlinearity poses significant challenges for developing analytical m...YBa_(2)Cu_(3)O_(7−δ)high-temperature superconductors(HTS)exhibit remarkable passive levitation over permanent magnet guideways(PMG),but the strong nonlinearity poses significant challenges for developing analytical models for HTS maglev systems.This paper presents a refined analytical method for calculating the electro-magnetic force in such systems.The method incorporates critical factors,including the complex properties of the superconductors,the Halbach PMG geometry,and various operation conditions.The derived analytical expressions explicitly reveal the interplay between system parameters and levitation performance.Experimental and numerical validation confirms the model’s high prediction accuracy in magnetic fields,levitation and guidance forces.A sensitivity analysis further identifies the most influential parameters such as thickness of the magnet,levitation height,Halbach wavelength.Moreover,this paper calculates and provides the recommended structural parameters for both rare-earth and rare-earth-free PMG.The potential of HTS maglev systems for heavy-haul applications is explored,demonstrating the capability to achieve significant levitation force(about 50 ton/m)under constrained geometric conditions.This work provides critical insights for minimizing permanent magnet consumption in HTS maglev systems and circumventing rare-earth material constraints.展开更多
文摘The rule of levitation force variation with different structure and electromagnetic parameters provides a basis for electromagnet design of electromagnetic suspension （EMS） medium and low speed maglev vehicles. In order to acquire accurate calculation results of levitation force, different calculation methods, including analytical method, 2D FEM （finite element method）, and 3D FEM, are applied to investigate the impact of various structural parameters, such as excitation current, air gap, lateral offset, and pole width, on levitation force. The analytical analysis is based on the classic mathematical model of levitation force between electromagnet and rail and performed with MATLAB. In the 2D and 3D FEMs, the numerical calculation of the levitation force is conducted with Ansoft by taking the magnetic saturation into account. In addition, the longitudinal end effect on the levitation force calculation is considered in the 3D FEM. The results show that the 3D FEM is the most accurate among the above three methods for calculating the levitation force, and the analytical method can only work for small current and/or large air gap conditions. A lateral- offset between vehicle and rail will reduce the levitation force; the levitation force descends sharply once the lateral offset exceeds the threshold, i.e., 8% of the pole width for U-shaped electromagnets. The maximum lift-to-weight ratio emerges when the pole width ratio of F type rail to electromagnet is 6：7. This may offer a reference for EMS maglev vehicle design and application.
文摘The dipole–dipole interaction model is employed to investigate the angular dependence of the levitation and lateral forces acting on a small magnet in an anti-symmetric magnet/superconducting sphere system. Breaking the symmetry of the system enables us to study the lateral force which is important in the stability of the magnet above a superconducting sphere in the Meissner state. Under the assumption that the lateral displacement of the magnet is small compared to the physical dimensions of our proposed system, analytical expressions are obtained for the levitation and lateral forces as a function of the geometrical parameters of the superconductor as well as the height, the lateral displacement, and the orientation of the magnetic moment of the magnet. The dependence of the levitation force on the height of the levitating magnet is similar to that in the symmetric magnet/superconducting sphere system within the range of proposed lateral displacements. It is found that the levitation force is linearly dependent on the lateral displacement whereas the lateral force is independent of this displacement. A sinusoidal variation of both forces as a function of the polar and azimuthal angles specifying the orientation of the magnetic moment is observed. The relationship between the stability and the orientation of the magnetic moment is discussed for different orientations.
基金supported by the National Natural Science Foundation of China(Grant Nos.51342001 and 50872079)the Key-grant Project of Chinese Ministry of Education(Grant No.311033)+3 种基金the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120202110003)the Innovation Team in Shaanxi Province,China(Grant No.2014KTC-18)the Fundamental Research Funds for the Central Universities,China(Grant Nos.GK201101001 and GK201305014)the Outstanding Doctoral Thesis Foundation Project of Shaanxi Normal University,China(Grant Nos.X2011YB08 and X2012YB05)
文摘The influence of the width of the middle magnet in the permanent magnet guideways （PMGs） on the levitation force and the levitation height of single-domain yttrium barium copper oxide （YBCO） bulks has been investigated at 77 K under the zero field cooled （ZFC） state. It is found that the largest levitation force can be obtained in the system with the width of the middle magnet of the PMG equal to the size of the YBCO bulk when the gap between the YBCO bulk and PMG is small. Both larger levitation force and higher levitation height can be obtained in the system with the width of the middle magnet of the PMG larger than the size of the YBCO bulk. The stiffness of the levitation force between the PMG and the YBCO bulk is higher in the system with a smaller width of the middle magnet in the PMG. These results provide an effective way to control the levitation force and the levitation height for the superconducting maglev design and applications.
基金National Natural Science Foundation of China(51033026,50872079)National High Technology Research and Development Program of China("863"Program,2007AA03Z241)Fundamental Research Funds for the Central Universities(GK200901017)
文摘Top seeded infiltration and growth technique(TSIG)is an effective method for the preparation of high quality large YBa2Cu3O7-x(YBCO)bulk superconductors.In this paper,single domain YBCO bulk superconductors,with different Y2Ba4CuWOy(YW2411)additions,have been fabricated by TSIG process.the solid phase pellet is made of a mixture of Y2BaCuO5(Y211)+xwt%YW2411 powders,x=0,1,3,5,7,9.The growth morphology,microstructure and levitation force of the YBCO bulks have been investigated,it is found that the levitation force is increasing from 23.05 to 33.6 N with the increasing of YW2411 addition from 0 to 5wt%,and decreasing from 33.6 to 21.59 N with the increasing of YW2411 addition from 5 to 9wt%,the largest levitation force is obtained when the YW2411 content is about 5wt%.This is very important for us to fabricate high quality YBCO bulk superconductors.
基金support from the PCSIRT of the Ministry of Education of China(IRT0751)the National Natural Science Foundation of China (Grant Nos. 50588201, and 50872116)+3 种基金the National High Technology Research and Development Program of China (863 program: 2007AA03Z203)the Research Fund for the Doctoral Program of Higher Education of China (SRFDP200806130023)the Fundamental Research Funds for the Central Universities(SWJTU09BR152 and SWJTU09ZT24)the Doctoral Innovation Foundation of Southwest Jiaotong University (X1899124710003)
文摘The super-high speed high temperature superconductor （HTS） maglev evacuated tube transport （ETT） is a promising transport mode for the future. As a key component of the HTS maglev vehicle, the permanent magnet guide- ways （PMGs） with different geometrical configurations and iron yoke widths are analyzed by finite element method （FEM）. The levitation force of a single onboard HTS maglev device over the designed PMG at different field cooling heights （FCH） is measured by magnetic levitation measurement system. Based on the designed PMG and experimental results, a preliminary scheme of subterranean super-high speed HTS maglev ETT is described in this paper. The HTS maglev ETT is mainly composed of an evacuated tube, HTS maglev vehicle, PMG, propulsion system, station, emergency rescue system, etc. In addition, a subterranean tube that consists of foundation tube and vacuum airproof layer is introduced. In order to convert the stress caused by the air pressure difference between inside and outside of the vehicle, a multi-circular vehicle body is designed. The vehicle is driven by a linear motor propulsion system under the control of a ground controlling system. The scheme of long-distance super-high speed passenger transportation is accomplished by the connection of different vehicles.
文摘The fabrication of large bulk high temperature superconducting YBCO samples was accomplished by melt-texture-growth(MTG) process with a seeding technique.The microstructure of the samples was observed by a polarization microscope.The observation shows that the samples have controlled orientation and large domains.The magnetic repulsion measurements as a function of distance were carried out.The maximum repulsion between the YBCO sample(29 mm in diameter and 10 mm thick) and a Nd-Fe-B permanent magnet with 0.5T surface magnetic field was 4.8 N/cm2 at 77K.The magnetic levitation on the samples exhibits anisotropic behaviour.
基金supported by the National Natural Science Foundation of China (Grant No. 52072229)the Key-grant Project of the Ministry of Education of China (Grant No. 311033)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. GK201706001)the Teaching Reform and Innovation Project of Higher Education in Shanxi Province, China (Grant No. J2021719)。
文摘To study the influence of thickness on the magnetic properties of ReBCO(Re = Y, Gd, Sm, Nd, etc.) bulk superconductors, a single domain gadolinium barium copper oxide(GdBCO) bulk superconductor fabricated by the Re + 011 top seeded infiltration growth(Re + 011 TSIG) method was continuously sliced along the bottom to obtain samples of different thickness. The levitation force and attractive force of these samples were tested at 77 K in the zero-field-cooled(ZFC)state. It is found that as the sample thickness decreases, the levitation force decreases gradually whereas the attractive force increases. This is related to the varied ability to resist the penetration of magnetic field occasioned by varying sample thickness, which are deeply revealed by combining with the characteristics of the non-ideal type-II superconductor. Further,the levitation force exhibits a trend of slow initial change followed by rapid change, which may be attributed to the growth of the sample. Measurement of the trapped field shows that a similar distribution of trapped field at the top and bottom surfaces can be achieved by removing some materials from the bottom of the bulk. These results provide a reference for meeting the actual requirements of ReBCO bulks of different thicknesses and greatly contribute to practical designs and applications.
基金supported by the National Magnetic Confinement Fusion Science Program (2011GB112001)the Program of International S&T Cooperation (S2013ZR0595)+2 种基金the National Natural Science Foundation of China (No. 51271155)the Fundamental Research Funds for the Central Universities (SWJTU11CX073, SWJTU11ZT16 and SWJTU11ZT31)the Science Foundation of Sichuan Province (2011JY0031 and 2011JY0130)
文摘Superconducting magnetic levitation performance, including levitation force and guidance force, is important for the application of high-temperature super- conducting maglev. Both of them are not only affected by different arrays of superconductors and magnets, but also by the thickness of the iron shim between permanent magnets. In order to obtain the best levitation performance, the magnetic field distribution, levitation force, and guidance force of a new type of three magnetic hills of permanent magnet guideway with iron shim of different thicknesses （4, 6, and 8 mm） are discussed in this paper. Simulation analysis and experiment results show that the guideway with iron shim of 8 mm thickness possesses the strongest magnetic field and levitation performance when the suspension gap is larger than 10 mm. However, with the decreasing of suspension gap, the guideway with iron shim of 4 mm thickness possesses the best levitation performance. The phenomena can be attributed to the density distribution of flux and magnetization of iron shim.
基金supported by the National Natural Science Founda-tion of China(U23A20681).
文摘YBa_(2)Cu_(3)O_(7−δ)high-temperature superconductors(HTS)exhibit remarkable passive levitation over permanent magnet guideways(PMG),but the strong nonlinearity poses significant challenges for developing analytical models for HTS maglev systems.This paper presents a refined analytical method for calculating the electro-magnetic force in such systems.The method incorporates critical factors,including the complex properties of the superconductors,the Halbach PMG geometry,and various operation conditions.The derived analytical expressions explicitly reveal the interplay between system parameters and levitation performance.Experimental and numerical validation confirms the model’s high prediction accuracy in magnetic fields,levitation and guidance forces.A sensitivity analysis further identifies the most influential parameters such as thickness of the magnet,levitation height,Halbach wavelength.Moreover,this paper calculates and provides the recommended structural parameters for both rare-earth and rare-earth-free PMG.The potential of HTS maglev systems for heavy-haul applications is explored,demonstrating the capability to achieve significant levitation force(about 50 ton/m)under constrained geometric conditions.This work provides critical insights for minimizing permanent magnet consumption in HTS maglev systems and circumventing rare-earth material constraints.
