Magnetic Rails Research Articles

New Application Method of Static-Field Magnetization to Magnetically Levitated Mover System With High T c Superconductors

Application method of static-field magnetization to magnetically levitated mover system with high critical temperature (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) superconductors is discussed. The system is composed of a levitated mover, magnetic rails, a linear induction motor (LIM) and some power supplies. In the paper, static-field magnetization is applied to superconductors in the levitated system from bottom superconductor surfaces. Then, magnetizations in superconductors are tried to control using static-field on superconductor surfaces. That is, magnetic flux density distributions are successfully forced to change to initial flux density distributions.

Dynamic Characteristics of the Manned Hybrid Maglev Vehicle Employing Permanent Magnetic Levitation (PML) and Superconducting Magnetic Levitation (SML)

A manned hybrid maglev vehicle employing permanent magnetic levitation (PML) and superconducting magnetic levitation (SML) was developed. It is mainly composed of a PML part, an SML part, and a maglev frame. The PML part with a repulsive force is designed to support the main load and the SML part with pinning forces is used to guarantee the lateral stability. The maglev frame is designed to support the vehicle body and connect the two maglev components. In previous studies, the sufficient levitation and guidance forces have been verified. In actual operation process, the dynamic characteristics are closely related to the stationarity, the comfortability, and the security of the maglev vehicle. Hence, the research on the dynamic characteristics of the maglev vehicle above the magnetic rails is required to ensure its safe operation. Measurements on vibration acceleration of the hybrid vehicle were conducted under different conditions, including different loads and different pulse excitations. Experimental results show that the dynamic behaviors are quite different between the vertical and lateral directions. In the vertical direction, by using linear bearings, the SML part and PML part are independent with two different natural frequencies and express passive stable characteristic on vibration acceleration curves. While in the lateral direction, the hybrid maglev vehicle has only one natural frequency, which decreases as the load onboard increases due to the decreasing levitation height of the PML part. These results help us to have an insight into the hybrid maglev vehicle employed SML and PML, and prove evidence for the following promotion and optimization.

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.

Mathematical model of levitating cart of magnetic UAV catapult

The article presents the steps of modeling of the dynamics of a levitating cart of an unmanned aerial vehicle (UAV) magnetic catapult. The presented in the article innovative catapult is based on the Meissner effect occurring between high-temperature superconductors (HTS) and a magnetic field source. The catapult suspension system consists of two elements: fixed to the ground base with magnetic rails and a moving cart. Generating magnetic field rails are made of neodymium magnets. Levitation of the launcher cart is caused by sixteen superconductors YBCO, placed in the cart frame supports. Described in the article model contains the system of Cartesian reference frames, kinematic constrains, equations of motion and description of forces acting on the cart as well as exemplary numerical simulation results.

New magnetic rails with double-layer Halbach structure by employing NdFeB and ferrite magnets for HTS maglev

In the high temperature superconducting (HTS) maglev system, the magnetic rail as an essential infrastructure is needed all along the route to carry passengers and goods to the destinations. Thus, large amount of rare earth magnetic materials are required in the magnetic rail construction. In order to decrease the dependence of magnetic rails on rare earth elements, the ferrite magnet is employed to replace part of the NdFeB magnets containing rare earth elements. Consequently, a new type rail with double-layer Halbach structure is presented, which is consisted of NdFeB and ferrite magnets. In this paper, we designed and fabricated the proposed rail, and further measured its magnetic flux density distribution and electromagnetic force interacting with HTS bulks. Experimental results indicate that, this new type rail, in double-layer Halbach structure, can achieve an equivalent distribution of magnetic flux density and levitation performance as the pure NdFeB Halbach rail, while a 10% reduction in NdFeB magnet consumption can be realized at the same time. In addition this work explores another magnetic material selection for HTS maglev applications. The dependence on rare earth element and the cost of magnetic rails can be further reduced, as the coercive force of ferrite magnets improved.

Field homogeneity improvement of maglev NdFeB magnetic rails from joints.

An ideal magnetic rail should provide a homogeneous magnetic field along the longitudinal direction to guarantee the reliable friction-free operation of high temperature superconducting (HTS) maglev vehicles. But in reality, magnetic field inhomogeneity may occur due to lots of reasons; the joint gap is the most direct one. Joint gaps inevitably exist between adjacent segments and influence the longitudinal magnetic field homogeneity above the rail since any magnetic rails are consisting of many permanent magnet segments. To improve the running performance of maglev systems, two new rail joints are proposed based on the normal rail joint, which are named as mitered rail joint and overlapped rail joint. It is found that the overlapped rail joint has a better effect to provide a competitive homogeneous magnetic field. And the further structure optimization has been done to ensure maglev vehicle operation as stable as possible when passing through those joint gaps. The results show that the overlapped rail joint with optimal parameters can significantly reduce the magnetic field inhomogeneity comparing with the other two rail joints. In addition, an appropriate gap was suggested when balancing the thermal expansion of magnets and homogenous magnetic field, which is considered valuable references for the future design of the magnetic rails.

Selective handling of droplets in a microfluidic device using magnetic rails

Droplet microfluidics is currently undergoing an explosive development due to its ability to compartmentalize samples in picolitre to nanolitre volumes, transport them without dispersion and perform high-throughput analysis. The precise manipulation of single droplets, however, still requires complex chips, such as microelectrode arrays, or equipment, such as laser-based sorting. We report here a very simple proof of concept of an innovative and active technology which allows the individual manipulation of single droplets. This technology combines ferromagnetic rails and magnetic nanolitre droplets. Ferromagnetic rails are used to locally create magnetic potential wells. When the field is turned OFF, the hydrodynamic drag force transports the magnetic droplets according to the flow velocity profile. By switching ON the magnetic field, droplets experience a magnetic force that affects their trajectory when passing over the magnetized rail. The combination of the drag force exerted by the oil flow and the magnetic force resulting from the magnetized rail leads to a deflection force that guides the droplet along the rail, thus imposing a deterministic trajectory. The magnetic rails networks offer a spatially and temporally addressable guidance and sorting of individual magnetic droplets by synchronizing field activation and droplets positions. Numerical simulations were performed to evaluate spatial distribution of both drag and magnetic forces within the microdevice. The influence of different parameters such as magnetic flux density magnitude, flow rate and orientation of the rail has been investigated. Finally, selective droplet sorting, parking and merging were demonstrated and the monitoring of parallelized enzymatic reactions was performed.

Trial Application of Pulse-Field Magnetization to Magnetically Levitated Conveyor System

Magnetically levitated conveyor system using superconductors is discussed. The system is composed of a levitated conveyor, magnetic rails, a linear induction motor, and some power supplies. In the paper, pulse-field magnetization is applied to the system. Then, the levitation height and the dynamics of the conveyor are controlled. The static and dynamic characteristics of the levitated conveyor are discussed.

A Superconducting Levitation Transport Model System for Dynamical and Didactical Studies

Abstract Superconducting levitation transport systems might become very attractive in the near future due to various reasons. The realisation of contactless systems allows e.g. extended maintenance-free operation with high efficiency since such a system only needs energy for cooling and propulsion. We established a small superconducting levitation transport model system called “SupraTrans Min” consisting of permanent magnetic rails and a levitated vehicle including four YBCO-bulk samples in a cryostat. The rail system consists of an oval shaped loop (2.90 m x 1.44 m), which was build up from individual linear and curved track modules. Inside the vehicle position variations of the superconductors are possible. By means of velocity, acceleration and temperature measurements different dynamical aspects of our complex levitation system can be investigated. We also show the broad applicability of the experimental setup for didactical studies in physics.

Optimization of a Linear Superconducting 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.

Basic Study on Magnetically Levitated Conveyor System Using Field-Cooling Magnetization and Pulse-Field Magnetization

Magnetically levitated conveyor system using superconductors is discussed. The system is composed of a levitated conveyor, magnetic rails, a linear induction motor (LIM) and some power supplies. In the paper, pulse-field magnetization is applied to the system from the upper superconductor surface. Then, the levitation height and the dynamics of the conveyor are controlled when the conveyor stops. The static and dynamic characteristics of the levitated conveyor are improved by using pulse-field magnetization.

Experiments in a real scale maglev vehicle prototype

A Brazilian real scale magnetically levitated transport system prototype is under development at the Federal University of Rio de Janeiro. To test this system a 180 m long line has been projected and it will be concluded by the end of 2010. A superconducting linear bearing (SLB) is used to replace the wheels of a conventional train. High temperature superconductor bulks placed inside cryostats attached to the vehicle and a magnetic rail composes the SLB. To choose the magnetic rail for the test line three different rails, selected in a previous simulation work, were built and tested. They are composed by Nd-Fe-B and steel, arranged in a flux concentrator topology. The magnetic flux density for those magnetic rails was mapped. Also, the levitation force between those rails and the superconductor cryostat, for several cooling gaps, were measured to select the best rail geometry to be used in the real scale line. The SLB allows building a light vehicle with distributed load, silent and high energy efficient. The proposed vehicle is composed of four modules with just 1.5 m of length each one and it can transport up to 24 passengers. The test line having two curves with 45 m radius and a 15% acclivity ramp is also presented.

連結式容器交換ロボットの開発

We have developed an autonomous robot carrying a heavy medicine container, to be used in the medicine factory. In this environment, its workspace is narrow and the robot has to negotiate between existing machines and instruments. It is also necessary for the robot to comply with strict GMP standards defined by Ministry of Health, Labour and Welfare, Japan for medicine production. The robot tows an empty container to the throw-in platform according to the instruction given by the process controller system via infrared communication. Once loaded, the container is again towed by the robot and stored at a designated position in the stowage area. The robot runs on magnetic rails autonomously and is able to tow a container weighing 200[kg], or heavier, and precisely position the container at the specified location with less than 10[mm] of error. The container is rigidly held by a specifically designed gripper on the robot during transportation to maintain precise motion and positioning of the container. Three robots have worked in a medicine factory for more than two years without causing a single interruption in the manufacturing process, achieving improved production efficiency, lowered production costs, with fewer workers attending the production line than before.

視覚によるライン・トレースと磁気タグの併用による走行制御を用いた搬送ロボットの開発

We have developed an autonomous robot carrying heavy product containers, to be used in the medicine factory. In this environment, its workspace is narrow and the robot has to negotiate between existing machines and instruments. It is also necessary for the robot to comply with strict GMP standards defined by Ministry of Health, Labor and Welfare, Japan for medicine production. The paper proposes a new navigation method using both vision and magnetic tags, rather than conventional magnetic rails on the floor. The robot tows product containers on a cart, and transfers them between a packer and a palettizer for wrapping, according to the instruction given by the process controller system via infrared communication. The robot runs on defined paths by detecting either a tape on the ceiling by vision, or magnetic field generated by small magnetic tags buried on the floor. The proposed method can achieve precision equivalent to the conventional method with magnetic tapes, and requires less initial installation costs. Three robots have worked in a medicine factory for more than a year without causing a single interruption in the manufacturing process, achieving improved production efficiency, lowered production costs, with fewer workers attending the production line than before.

Study on Magnetically Levitated Conveying System Using Hybrid-Magnetized High $T{\rm c}$ Superconductors

As an application of superconductors, we propose a magnetically levitated conveying system for clean rooms or vacuum chambers of semiconductor manufacturing industry. By using the pinning effect of superconductors, it is possible to make a stable levitation system without any mechanical contacts. This system consists of a levitated conveyer and a pair of magnetic rails. Considering a practical use of magnetically levitated conveying system, it is necessary to change levitation forces and stiffness. In this paper, we tried to apply pulsed-field magnetization (PFM) to improve the system. Moreover, dynamic characteristics of the levitated system are discussed to verify the effect of PFM for the system.

A Self-Tuning Regulator for the High-Precision Position Control of a Linear Switched Reluctance Motor

In the high-technology mass manufacturing industry, high-speed and high-precision motion is an indispensable element in the automated production machines. In recent years, there has been a growing tendency to employ direct drive permanent magnet linear synchronous motors in demanding motion applications. Although the overall performance is good, its implementation cost remains high. This is mostly due to the cost of the Neodymium-Boron magnets, the manufacturing of the magnetic rails, and the precision of the overall mechanics. In this paper, a much cheaper alternative is proposed-to use a low-cost linear switched reluctance motor (LSRM) and an adaptive control strategy to overcome the tolerances and difficult control characteristics inherent in the motor. The LSRM has simple and robust structure, and it does not contain any magnets. However, its force is solely drawn from the reluctance change between the coil and the steel plates. Variations on the behavior of these two elements due to different operating conditions will change the motion behavior of the motor. Also, to keep the overall cost low, the LSRM sets a marginal mechanical tolerance during its mass production. This leads to characteristic variations in the final product. Finally, since the LSRM is a direct drive motor, any variations on the motor characteristics will directly reflect on the control system and the motion output. In this paper, a self-tuning regulator (STR) is proposed to combat the difficulties and uncertain control behaviors of the LSRM. This paper first introduces the motor winding excitation scheme, the model of the LSRM, and the current control method. The LSRM system is modeled as a single-input single-output discrete model with its parameters estimated by the recursive least square (RLS) algorithm. Then, an STR based on the pole placement algorithm is applied to the LSRM for high- performance position tracking. Both the simulation investigation and the experimental verification were conducted. In both cases, the results verified that the proposed RLS algorithm can estimate the parameters with fast convergence. The STR can provide quick response and high precision which is robust to the change of system parameters. Combined with STR control, the LSRM is a low-cost solution to fast, accurate, and reliable position tracking for many demanding motion control applications.

Magnetic Drag Force due to Iron Losses in Magnetic Rail of Magnetically Levitated Train.

Large eddy current is induced at high speed in a slub type rail of a electromagnetically levitated train. The eddy current causes magnetic drag force and decreases attracting force between the magnet and the rail.In this paper, magnetic drag force in a system, which has magnetic rails made of laminated iron sheets, was studied theoretically and experimentally, and the following results were obtained:(1) Magnetic drag force in a system with a laminated iron rail was measured using a rotary disc type apparatus. Calculated values were simulated with 2-dimensional finite element method. The calculated values of magnetic drag force were approximately equal to the measured values, and the difference between the calculated and the measured values was within 10%. This result shows that the theory is reasonable.(2) The ratio of magnetic drag force to magnetic attracting force of a slub type rail is about a few %. It was confirmed that the ratio of a laminated rail in this paper was less than 0.3% and that adoption of laminated rails is effective.(3) The magnetic flux density in the air gap between the magnet and the laminated iron rail does not decrease at high speed of 170km/h. This indicates that the attracting force is constant even at high speed and therefore stable levitation charcteristics will be obtained.

A demonstration of the linear Meissner effect using high-temperature superconductances

The use of toys made from high-temperature superconductors in demonstrations of magnetic levitation and the linear Meissner effect is discussed. The construction of some small toys and a magnetic rail that allows students to magnetically levitate a toy train which can be made to follow a roller-coaster-like track are described. The magnetic rails may include straight lines, curves, spirals, and Y junctions. The toys are launched by letting them float down a small incline and smoothly along the rails. The approach provides an interesting way for students to learn about superconductors and magnetic levitation. An extension of this approach could provide a basis for serious calculations of lifting power, drag, etc. >

Analysis of magnetic drag of electromagnetic levitation system with magnetic rails unified for both levitation and propulsion

Analysis of magnetic drag of electromagnetic levitation system with magnetic rails unified for both levitation and propulsion