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In the past years, different superconducting levitation systems were developed around the world. Most projects focused on optimizing the flux density in the working space of the superconductor in order to maximize the levitation force of the system. In general, these systems use tracks with permanent magnetic Halbach arrays or combine permanent magnets with steel yokes to maximize the usable flux density. Therefore, none of these tracks can easily be switched off to allow a safe crossing or to build a fast turnout switch without moving parts. A new track was designed containing permanent magnets and a YBCO-tape-coil to realize a fast switchable track. In this concept, the permanent magnets provide the flux used for levitation, whereas the coil controls the flux in the space above the track, where levitation usually takes place. The magnetic behavior of this new design was studied and improved with two-dimensional (2-D) and 3-D simulations. Afterwards, a demonstrator was built on which the induced magnetic field was measured in the different operation modes. The results of the measurements and the simulations indicate that the flux density above of the track might be controlled by the coil current. It was proven that the new track design generates magnetic fields comparable to the standard permanent magnetic track, whereas only residual fields are measured in inactive mode, which can be further reduced with negative coil currents.

The levitation force between a permanent magnet (PM) and a high-temperature superconductor (HTS) bulk has resulted in various industrial applications. PMs’ volume has a substantial role in the cost of PM guideways (PMGs), especially for long-distance transportation, which necessitates the optimum arrangement for PMs. Halbach array has proved considerable levitation force because of its one-sided magnetic field among the other known arrangements. In this paper, a variety of Halbach PMG structures with varying PM magnetization angles are simulated and the impact of PM angular magnetizations on the levitation force is investigated. A heuristic method has been proposed to acquire the optimum magnetization angles that maximize the levitation force. This optimum design decreases the total cost due to the minimum PM use besides providing a satisfactory stable levitation for a specified levitation height, PMG width, and HTS disk’s characteristics. Prototypes have been developed based on the optimized PMG designs with the satisfactory results, compatible with the analytical and simulation results.

This paper describes the levitation and guidance characteristics of a semi-high-speed magnetic levitation (MAGLEV) vehicle. For a MAGLEV, which operates at 200 km/h, the guidance magnet is essential for high-speed operation at curves and against a side wind. The levitation and guidance magnets are electromagnetically and dynamically coupled, because both are used in a single rail. Because of the interactions between the levitation and guidance systems, clear establishment of their correlation is required for robust and stable control. We identify the electromagnetic/dynamic correlation of the levitation and guidance systems of the MAGLEV using a magnetic equivalent circuit and motion equations. A controller is developed to realize stable control by considering the system correlation. The control properties are obtained through simulation to achieve stable levitation and guidance.

A passive magnetic levitation (maglev) carrier is a transportation device that is based on magnetic levitation and does not have any electric circuits on the moving part. Because the actuation devices are not in the moving platform for passive operation, the levitation forces are non-homogenous. This characteristic makes the design and control of the system challenging. We present design and control procedures for a passive maglev carrier system. To achieve stable and accurate levitation, mechanical analyses were performed to determine the configuration and locations of the levitation magnets. The key challenge in the control design is that the locations and magnitudes of the levitation forces are not continuous around the edge of the moving platform when it passes the magnet. Therefore, the longitudinal positions of the magnets relative to the moving platform are a noise (uncontrollable) factor for the controller. The control parameters should be robust against the noise factor to achieve reliable performance. The Taguchi method was used to determine the optimal control parameters in the presence of the noise factor. The optimized gain reduced the position variation of the levitated carrier by 50% in terms of the root mean square error.

In this study, the noncontact magnetic levitation system using combined high temperature superconducting (HTS) bulk annuli and ring-shaped permanent magnet (PM) was proposed. In the suggested levitation system, the HTS bulk annuli were magnetized by ring-shaped PMs fixed between the HTS bulk annuli, so there was no more need to apply source for magnetization. In this paper, the levitation forces on the radial and axial directions were measured using 1 PM + 2 bulks (1 unit) and 2 PM + 3 bulks systems to study the optimization of levitation system. To improve the levitation property of proposed levitation system, the shape of PM and materials of the rotor shaft were studied experimentally.

A levitation configuration is reported wherein diamagnetic levitation, weight compensated diamagnetic levitation and diamagnetically stabilised levitation are combined. The configuration allows the simultaneous inline triple levitation of three different bodies without the need of energy input or feedback control. The proposed levitation setup could find application in sensitive multi-range seismometers or accelerometers wherein levitating seismic bodies with different masses and resonance behaviour are needed.

A small superconducting maglev propeller system, a small spacecraft model suspending and moving around a terrestrial globe, several small maglev vehicle models and a magnetic circuit converter have been designed and constructed. The track was paved by NdFeB magnets, the arrangement of the magnets made us easy to get a uniform distribution of magnetic field along the length direction of the track and a high magnetic field gradient in the lateral direction. When the YBCO bulks mounted inside the vehicle models or spacecraft model was field cooled to LN 2 temperature at a certain distance away from the track, they could be automatically floating over and moving along the track without any obvious friction. The models can be used as experimental or demonstration devices for the magnetic levitation applications.

A design for a passive magnetic bearing system that can stably levitate a rotor in all directions is described. The bearing system consists of levitation magnets coupled with a Halbach array stabilizer, which induces currents in stabilization coils, in order to overcome the inherent instability of a system composed only of permanent magnets. The levitation magnet system consists of two pairs of annular ring magnets which provide an upward magnetic levitation force to counteract the downward gravitational force of the rotor. The Halbach array stabilizer consists of two stabilization coils shifted in angular position with respect to one another and centered in the vertical direction between two rotating Halbach arrays. Magnetic fields from permanent magnets are calculated using superposition of fields due to patches of magnetization charge at surfaces where the magnetization is discontinuous. Induced currents in the stabilization coils are calculated by computing the time derivative of the magnetic flux through those coils. Magnetic forces on the rotor are computed using a superposition of forces on each patch of magnetization charge. The entire magnetic bearing system, consisting of both the levitation magnets and the Halbach array stabilizer, is stable to both vertical and lateral displacements. Results are compared with a simpler straightened approximation of the Halbach array stabilizer.

This paper proposes an analytical levitation force computation method using the equivalent magnetic circuit (EMC) of a controlled-permanent magnet (CPM) levitation system that has potential applications in a magnetically levitated vehicles. The airgap field and levitation force characteristics of the CPM are investigated using the EMC, considering airgap fringing and leakage flux path for longitudinal and lateral direction surfaces. The computation results are validated using finite-element analysis and experimental results. The levitation performance was tested using a dynamic force test facility, which confirms the validity of the EMC computation scheme for the description of a CPM levitation system.

The Laboratory for Applied Superconductivity of the Federal University of Rio de Janeiro (LASUP) has been developing a superconducting magnetic levitation urban train named MagLev-Cobra. It is a kind of light rail vehicle where the conventional wheel-rail track is substituted by a rail of Ne-Fe-B magnets and carbon steel interacting with superconductor bulks installed in the vehicle to promote levitation. The main cost of this levitation system is the magnetic rail. Therefore, any improvement in the shape and configuration of magnets and iron has a significant budgetary impact. In this paper, the optimizations carried out with the feasible direction interior point algorithm, extensive search, and genetic algorithm of magnetic rails are presented. The objective is to find the geometry that minimizes the total cost, for a given levitation force, considering some practical restrictions. The levitation force restriction is calculated using a finite-element method. During the optimization process, the superconductor null permeability model is used. Finally, the results are checked with the Bean model and verified experimentally. Measurements of the levitation force and the field mapped over the magnetic rails are presented. Significant reduction of soft and hard ferromagnetic materials was reached.

The gradeability is one of the advantages of the high-temperature superconducting (HTS) maglev vehicle, and it is relative to the levitation characteristic of the maglev system on the ramp. The influence of the ramp angle on the levitation characteristics of the HTS maglev model was investigated. Some levitation characteristic parameters on the uphill guideway with different ramp angles were studied by the equivalent experiment, such as the levitation force, the levitation gap, the levitation stiffness and the guidance force. Compared with the experimental results on the horizontal guideway, it was found that the levitation gap increased, but the levitation force and the levitation stiffness decreased. The levitation gap and the levitation stiffness are considered as the main maglev characteristic parameters needed to be taken into account.

The fundamental electromechanical interactions in a passive null-flux electrodynamic maglev system (EDS) are mediated by the voltages induced in the levitation coils by the sled magnets, and by the forces exerted on the sled as a result of the induced currents. This work presents a reliable and compact method to calculate these interactions by using analytical expressions of the magnetic field of a permanent magnet. The proposed approach provides a highly efficient and numerically stable approach to the computation of the flux induced in the levitation coils as well as the induced voltages and currents and lift, drag, and guidance forces acting on the sled's magnets. The analytical model is compared to a simplified algebraic model suitable for real-time control of EDS maglev suspension dynamics. Both models are compared with measurements and show good predictive quality.

This papers presents technology aspects and choices relative to worldwide MAGLEV projects such as the German Transrapid, the Japanese MLX, the USA Inductrack and the Swissmetro. Propulsion, magnetic levitation and guidance, transfer of energy to the vehicle are investigated.

Arising out of research at the Lawrence Livermore National Laboratory on passive magnetic bearings, a new magnetic levitation system, the Inductrack, has been developed and tested at model scale. The system employs special arrays of permanent magnets (Halbach arrays) on the moving car. The magnetic field from the arrays induces repelling currents in a close-packed array of shorted circuits in the track. Above a low transition speed (a few kilometers per hour), levitation forces approach a constant value, while drag forces decrease inversely with speed, with L/D reaching 200:1 or more at operating speeds. The high magnetic efficiency of the Halbach arrays, plus the use of close-packed track circuits, results in levitating forces approaching 40 metric tonnes per square meter (using NdFeB permanent magnet arrays, whose weight in typical cases is a few percent of the levitated weight). The system is passively stable: only motion is required for levitation. Failure of the drive system only results in the train slowing down and settling onto auxiliary wheels at a low speed. A detailed theoretical analysis of the Inductrack was made, on the basis of which a small-scale model was constructed and operated. The Laboratory is building a new small-scale model system (under NASA sponsorship) to demonstrate the acceleration rates and speeds (10-g and Mach 0.4 in the model) needed to magnetically launch rockets.

A principle of hybrid magnetic levitation system using permanent magnets (PMs) and high-temperature superconductors (HTSCs) for a linear-motor-type carrier system in a high-quality clean room and a magnetic bearing for the flywheel energy storage system are discussed. A substantial levitation force was generated by the repulsive force between like poles of coupled magnets. However, the repulsion system with magnets is essentially unstable without control. Thus, HTSCs are applied for control elements of the PM-HTSC hybrid magnetic levitation system. In this system, the levitation force becomes stronger than in the system without PM, and we can expect sandwich-type magnetic bearing capable of sustaining greater force. © 1998 Scripta Technica, Electr Eng Jpn, 124(4): 56–63, 1998

A fast computer code that generates currents and forces for multiple magnetic levitation (MAGLEV) vehicle coils over a discrete guideway of arbitrary geometry has been developed, tested, and verified. A study of coil dimensions for overlapping loops, ladders, and discrete loops has been conducted to determine the optimal guideway design. A parameter known as "figure of merit" has been defined to assist in evaluating the level of "merit" for a particular track configuration. From this, it has been discovered that, for most cases, ladder tracks are a better configuration over both overlapping and discrete loops. On closer inspection, it was also discovered that an aspect ratio of unity for the dimensions of a ladder track yields the best overall results.

This paper describes the levitation mechanism of a maglev planar transportation vehicle. Levitation force is generated using magnetic wheels and nonmagnetic conductor. The combination of the linear induction motor mechanism enables the vehicle to do planar motion. The effects of the major design parameters are estimated through the analysis and experiments. Parametric design to get required performance of the levitation mechanism is achieved using those design parameters.

All electro-dynamic levitation systems (EDS) have peak drag forces and peak and average power consumption to deal with in order to be viable in Maglev applications. Both factors affect the energy cost and the capital cost of the propulsion system. A significant improvement for EDS systems is a so-called null-current configuration. It consists of two Halbach arrays, one above the track and one below the track. The two arrays are oriented with respect to one another so that their horizontal field components add while their vertical field components oppose. In this way, the levitating field component is enhanced while the field component that excites the currents in the ladder-track between the two arrays is weakened. The basic idea is that the lower induced current and the higher levitating field component produce the necessary levitation force. At the same time the drag force is much lower, since it depends on the product of the induced current and the vertical field component.

Recently, with the advance of materials processing techniques, such as top-seeding and melt-texturing (TSMT) method, very large single-grained Y-Ba-Cu-O (YBCO) samples up to several centimeters in diameter can be produced. Each sample is capable of levitating over kilograms of weight. A HTS magnetic levitation (MagLev) transportation prototype has been constructed at National Cheng-Kung University (NCKU) to validate the concept of HTS-MagLev system based on Meissner effect. This HTS-MagLev is an inherent stable levitation system, unlike traditional MagLev system that requires sensors and feedback circuits to dynamically adjust its unstable levitation position. In this report, the results of various magnetic levitation parameters, such as different permanent magnet configurations, relative levitation stability, levitation force, etc., as well as magnetic field intensity and distribution will be discussed.

Magnetic levitation type seismic isolation device composed of HTS bulks and permanent magnets can theoretically remove horizontal vibration completely. It is, however, not easy to generate the large levitation force by using only the levitation system composed of HTS bulk and permanent magnet (HTS-PM system). We focused on a hybrid levitation system composed of the HTS-PM system and the PM-PM system composed of only permanent magnets and investigated the suitable arranging method of the hybrid system for improving levitation force and obtaining stable levitation. In order to clarify the most suitable permanent magnet arrangement in the PM-PM system for the levitation force improvement, repulsive force between permanent magnets was measured in various kinds of the PM-PM system. The maximum repulsive force per unit area in the PM-PM system was at least three times larger than the levitation force per unit area in the HTS-PM system, so that the levitation force in the hybrid system was larger than that of the HTS-PM system. Stable levitation was also achieved in the hybrid system. This is because repulsive force in the PM-PM system against horizontal displacement was much smaller than restoring force in the HTS-PM system.

The unique properties of superconductors make the design of levitation devices possible. In some of them, lateral displacements of the superconducting levitating part often result in a decrease in the levitation force, which can cause a critical malfunction of the system. In this work, the authors theoretically analyze the levitation force of a system consisting of an infinitely long superconductor over an infinitely long permanent-magnet guideway using a realistic model based on a magnetic-energy minimization procedure, from which they give the physical keys for understanding the levitation force reduction after lateral displacements and how to minimize these effects.

Levitation force is studied in a two-dimensional system consisting of an infinitely long superconductor immersed in the magnetic field created by different arrangements of infinitely long parallel permanent magnets, based on the critical-state model using the magnetic energy minimization procedure. Results on force, stability, and losses in the levitation process in this system are analyzed.

A large scale test facility for the high speed ground transportation system TRANSRAPID has been built in Emsland. In the near future this test facility will show the economic feasibility of such a system. An essential component of this system is the magnetic levitation and guidance system of the vehicle. The requirements on this suspension system are: good ride comfort, high reliability and low operating costs. The elements of the suspension system are controlled cross field electromagnets with massive iron cores and rails for guidance and controlled longitudinal field magnets with a laminated iron core and rail for levitation. The reason for lamination is the combination of three operating tasks in the levitation magnets. These are: levitation, propulsion, and inductive power transfer to the vehicle. These magnets generate the exciting field of the synchronous linear motor. Due to these tasks the theoretical model for a levitation magnet has to be expanded in order to be able to describe these effects in dynamic simulations. The mechanical and the electrical structure of the suspension system must have several redundancies in order to get a high overall safety.

The dynamic circuit theory for the analysis of the suspension characteristics of electrodynamic magnetic levitation schemes for realistic magnet and guideway configurations is reviewed. Electrodynamic forces and moments have been measured on a large-scale stationary superconducting magnet interacting with an aluminum strip mounted on the rim of a 7.6-m diameter rotating test wheel. Good agreement is found between analytical and experimental results over the speed range to 100 km/h for the electrodynamic forces of test configurations which provide a rigorous test for theory. The speed dependence of moments is reported and used to estimate the force distribution on the superconducting coil. The dynamic circuit theory is then used to determine the suspension characteristics of the levitation system for the proposed Canadian Maglev vehicle.

Thermographic techniques and rotating wheel experiments are used to examine magnetic forces and dynamics of levitated models. Induced track current and magnetic pressure distributions for moving superconducting levitation coils are infered from laboratory tests on coils with sinusoidal currents. Magnetic search coils and liquid crystal and infrared thermography are used to determine current patterns in thin aluminum plates. Theoretical justification for these methods is given and shows that sinusoidally induced patterns are similar to motion induced current distributions in the high speed thin track limit. The dynamics of a freely magnetically levitating model on a "V" groove rotating thin track shows that stable motions are possible for the "V" track. These tests also show that drag coupled yaw-roll-lateral instabilities are possible for certain model geometries.

The most important versions of the magnetic levitation technique are expounded in the following. The programme of the magnetic levitation development in the Federal Republic of Germany including the choice of the electromagnetic levitation technique and its development up to operational readiness are also described and accounted for. The present survey emphasizes the main advantages of the levitation system due to its specific characteristics, defines fields of application and shows concrete possibilities of use. Ways for an optimum development are briefly pictured.

A magnetic levitation system utilizing superconducting magnets is now being developed for a high speed ground vehicle. From a view point of ride quality, a damping force for the mechanical oscillation of a levitated vehicle is one of the most important problems in this levitation system. This paper presents the analysis of the magnetic damping force in a loop track magnetic levitaion system; the magnetic damping force is caused by track loops. It is theoretically pointed out that the magnetic damping force is "negative" except in an extremely low velocity range. The theory is applied to the estimation of the magnetic damping force in a train model of practical interest. The results of the estimation suggest that the negative magnetic damping force is considerably large in a median velocity range (100 ∼ 200 km/h). Passive damping has been also investigated; it is found that damper loops installed in the levitation cryostat is effective even in persistent mode operation. It is concluded that rather good ride quality will be obtained by use of the passive damping method.

An outline of the magnetic levitation project in Japan is given. Research has been concentrated on levitation system utilizing electromagnetic repulsive force between a normal metal track and on-board superconducting magnets. Development of levitation magnets together with other items basic for a levitation system is given.

According to the div B = 0 condition, permanent magnetic levitation along a track is possible with stable characteristics in only one dimension. Mostly, the vertical dimension will be preferred. Transverse stabilization is achieved by guide rollers and inductor combs of linear motors, respectively. If no high stability is required in the vertical dimension, e.g., because disturbing forces are small, the arrangement of magnets in the track can be designed in such a way that weak stability in the vertical direction results in weak instability in the direction transverse to the track. The lateral forces, which now have only weak destabilization effects, can be overcompensated by the centering forces of double comb linear induction motors. This weakly unstable characterristics of the levitation system entails major energy conservation as a result of lower ohmic losses in the reaction rails. A model exhibiting these weakly unstable characteristics has been investigated. Such levitation system can be made of two V-shaped grooves consisting of permanent magnetic dipole plates.

A survey of present proposals for magnetic levitation is presented, in addition to a brief discussion of various factors involved in the development of such a mode of suspension. While the variety of possible systems is considerable, only a few of these have been adequately researched. In the United States, emphasis has been placed upon systems obtaining levitation heights of several inches, derived from the repulsion arising between a moving superconducting coil and a metallic track in which currents are induced. In England, efforts have been concentrated on suspension utilizing the repulsion of permanent magnets; while clearances are small (roughly 1 cm.), drag losses inherent in the American schemes are absent, and levitation exists without the necessity for the forward motion of the vehicle. The development of magnetic suspension has not advanced far beyond the stage of theory, fundamental experiment, and demonstration of models. For this reason, it is expected that magnetic suspension, while having s...

The characteristics of an auxiliary damper winding to improve the dynamic performance of the electrodynamic levitation system have been investigated. Passive and active damping are included in the study.

The basic properties of flat sheet and flat ladder levitation systems are compared and contrasted based on the assumption that identical quantities of material are used in their construction. It is shown that although ladder systems can produce slightly better lift-to-drag ratios, the overall performance of sheets is better, particularly where lateral destabilization must be minimized.

Simple "best case" calculations of power/lift and lift/ weight ratios for electromagnetic levitation systems using controlled permanent magnets are presented. The use of ferrite, alnico, and rare-earth permanent magnets is considered and it is shown that their use can substantially improve the potential performance of such systems. A major difficulty is that the very small control powers obtained may severely limit the stable dynamic operating range.

This paper describes the dynamics of the propulsion and levitation systems in the Maglev vehicle M-Bahn for low-speed urban transportation in which a controlled permanent-magnet-(PM) linear synchronous motor (LSM) is used and controlled for its propulsion and levitation. An elevated guideway is periodically supported by pillars and approximated by a sinusoidal track. To compensate for the static instability of the propulsion and levitation systems, the state feedback controllers for both systems are designed for the Maglev M-Bahn. The transient responses of the systems to the external step forces given in the longitudinal and/or vertical directions are simulated using the non-linear dynamic equations of the propulsion and heave motions, which were derived on a basis of the theory of the controlled-PM LSM presented previously by the authors.

The levitation force and thrust in a current-controlled single-sided linear induction motor which propels electrodynamically-levitated vehicles are discussed. It has been shown theoretically that the single-sided linear induction motor (SLIM) can operate satisfactorily over suitably large clearance gap compared with the effective height of electrodynamic suspension. The levitation force in SLIM can be used practically as an alternative levitation force in the low-speed region by supplying a primary current several times the rated current within the very short acceleration times. In high-speed Maglev vehicle system with electrodynamic suspension and SLIM propulsion, the aluminum plate for levitation can be saved for the distance to accelerate the vehicle to speeds sufficient for electrodynamic levitation by the cryogenic magnets.

Recently, magnetic levitation device have been attractive. In magnetic levitation system we think PM-type magnetic levitation system is suitable for convyer system in facilities. From this viewpoint, we studied the PM-type magnetic levitation system, and we successfully levitated such devices. But then its structure was very unstable in control, so it had to control in a small compass and seosors and control system had to be precise. To control it easy, we thought the method to reduce lateral force by new arrangement of PMs. It's the way which arranges vehicle side PMs in parallel to the track side PM and we analyzed the repulsive force based on surface current on PMs. By this method, we have reduced lateral force by arrangement of PMs. To verify the calculated characteristics, we made the equipment to measure the repulsive force and we obtained measured value. The measured value agreed well with calculated value. We verify the method of analysis and the possibility to reduce lateral force by the arrangement of magnets.

Analyses have been made of the design parameters which affect the magnetic lift and drag forces on the magnetically suspended very high speed train models of practical interest. In the suspension systems investigated here, the superconducting magnets are installed in the train and the roadbed is equipped with normal-conducting coils. As a result of this investigation, an improved suspension system is proposed, which consists of "ladder-type conductor" in the roadbed. This new system is investigated theoretically.

It has been generally believed that the magnetic levitation of trains of the induction-repulsion type needs large ampere turn on the train magnets, and only superconductive magnets make the magnetic levitation feasible. However, the magnetic levitation becomes feasible also with the normal conductive electromagnet if the iron magnetic path is properly provided. An experimental example has been investigated. For details, see Digests of the 1972 Intermag Conference (available from IEEE Headquarters).