Permanent Magnetic Levitation Research Articles

Automated people mover: a comparison between conventional and permanent magnets MAGLEV systems

An automated people mover (APM) is a system used in urban/suburban areas to transport passengers point to point with a high frequency and a reliable service. Although conventional wheel-on-rail/route systems are commonly used in APMs, the application of the magnetic levitation (MAGLEV) technology in this field sounds promising. Since this technology replaces the wheels by electromagnetic systems, there is no contact between the levitating vehicle and the guideway. This implies zero wear, reduced maintenance and virtually no noise and vibrations. Efficiency, lightweight and cheapness represent expected additional benefits. The aim of thisstudy is to show, through a theoretical analysis based on a real APM and on a simulated automated MAGLEV people mover (AMPM), how the low-speed MAGLEV applications can compete with conventional wheel/rail technology. The levitation and guiding forces in a permanent magnets-based AMPM have been obtained by using an FEM code. Then, a simulation tool, based on Modelica language, has been developed to perform a comparison between a conventional APM and an AMPM, in terms of power and energy requirements engaged in urban routes. Finally, a brief preliminary estimation of costs for the major AMPM subsystems has been presented.

Design and fabrication of a hybrid maglev model employing PML and SML

A hybrid maglev model combining permanent magnet levitation (PML) and superconducting magnetic levitation (SML) was designed and fabricated to explore a heavy-load levitation system advancing in passive stability and simple structure. In this system, the PML was designed to levitate the load, and the SML was introduced to guarantee the stability. In order to realize different working gaps of the two maglev components, linear bearings were applied to connect the PML layer (for load) and the SML layer (for stability) of the hybrid maglev model. Experimental results indicate that the hybrid maglev model possesses excellent advantages of heavy-load ability and passive stability at the same time. This work presents a possible way to realize a heavy-load passive maglev concept.

PERMANENT MAGNET LEVITATION IN A REGION WITH DIAMAGNETIC BOUNDARIES WITH A VERTICAL AND HORIZONTAL ORIENTATION OF A MAGNETIC FIELD

Permanent magnet levitation in a region with diamagnetic boundaries with a vertical and horizontal orientation of a magnetic field

Eddy damping effect of additional conductors in superconducting levitation systems

Abstract Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC–PM levitation system, the HTSC with higher critical current density J c can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC–PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c , damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c / V Cu , in which V Cu is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.

Study of the load reduction for hydro-generator bearing by hybrid magnetic levitation

To solve the problem of heat and friction existing in weight bearing of the hydraulic generator, a new type of magnetic levitation devices is proposed. The devices consist of electromagnetic and permanent magnetic levitation, which share together most of the hydraulic generator rotor weight to reduce axial load on thrust bearing. The permanent magnetic levitation is performed by new repulsive ring Halbach arrays. The new Halbach arrays are analyzed by using magnetic potential equations and superposition principle, and the magnetic flux density formulas are obtained. The formula results are verified by FEM. By further study of 3D model simulation analysis, it is confirmed that the new repulsive ring Halbach arrays can reach the design goal on actual working conditions.

Numerical study of the relation between the thermal effect and the stability of the levitation system excited by an external source

In this paper we present a numerical analysis of dynamic features of the levitation system generated by an interaction between a levitated permanent magnet (PM) and a high-Tc superconductor (HTSC) excited by an oscillatory external source where the thermal effect inside the superconductor is taken into account in a macro-model of superconductivity. The comportment is comprehensively displayed by comparing the dynamic responses of such systems in which the thermal effect in superconductor is and is not taken into account. The obtained results show that the thermal effect is related to the stability of the levitation system. This effect appears significantly in the case of unstable levitation systems. The results obtained show that the thermal effect and the stability of the levitation system depend mainly on some parameters related to the external source, such as the frequency and the amplitude of the applied external source. In this paper, the numerical problem is solved by using the control volume method (CVM) and the electromagnetic and thermal coupling is ensured by an alternate algorithm.

A Hybrid High-<i>T<sub>c</sub> </i>Superconducting Magnetic Levitation Sculpture Model

Different from other applications, this paper explores how to use the stable high-Tc superconducting (HTS) magnetic levitation (maglev) to lift the sculpture art to a high levitation position for satisfying the artists requirement for the light artistic concept. With a combination of the permanent magnet (PM) levitation and HTS maglev technologies, a sculpture model was built to sustain a stable levitation with a levitation height of over 80 mm. In this hybrid HTS maglev sculpture model, three PM rings are arranged as upper, middle, and bottom as a double-layer axial levitation structure; six rectangular YBaCuO bulks are fixed along the side of the PM rings upper-layer as a stabilizer component along the radial direction. When the bottom PM ring was driven up by the lifting bolt, the upper PM ring, which was fixed with the art, can be lifted much higher. Then the required artistic effect will be enhanced. After the model was designed and optimized by finite element method, it was experimentally validated by the HTS maglev measurement system. This levitation design is helpful to the realization of a real-scale levitation sculpture art, and can also provide references to superconducting radial magnetic bearing systems.

The Influence of Excitation Frequency on Magnetic Levitation Systems with a High-T c Superconductor

In this paper we present a numerical analysis of dynamic features of the levitation system generated by an interaction between a levitated permanent magnet (PM) and a high-T c superconductor (HTSC) excited by an oscillatory external source. The obtained results show that the value of the frequency (f free) of the PM displacement in the case of the levitation system generated by an interaction between a levitated PM and a fixed HTSC is equal at the resonance frequency (f re) of the levitation system generated by an interaction between a levitated PM and HTS excited by an oscillatory external source and the resonance frequency (f re) is mainly dependent upon the cooling position (Z 0) and the mass of the PM. The numerical problem in this paper is solved by using the control volume method (CVM).

An Analytical 3-D Model for Calculating Eddy-Current Damping Force for a Magnetic Levitation System With Permanent Magnet

An analytical solution for obtaining steady-state eddy-current-based force on a levitated permanent magnet above a plate with linear conductivity in the field of an electromagnet having cylindrical symmetry is presented in this paper. In literature, the force due to eddy current in this levitation system have been used for high precision positioning of a levitated permanent magnet without providing an explicit analytical model. In this system, a change in the coil's current and also the motion of the levitated permanent magnet in 3-D space generate eddy current in the plate. A novel explicit solution for obtaining damping forces due to these eddy currents is obtained as a function of geometric and material properties of the system. The analytical solution is derived by solving the quasi-static Maxwell equations using separation of variables method. Comparisons show that the analytical solution closely matches with the results of the finite element analysis.

Basic Study on Superconducting Magnetic Bearing (SMB) With Superconducting Coil

Our group has developed a superconducting magnetic bearing (SMB) with superconducting coil for magnetically levitated conveyers used for clean environments. The SMB is composed of a levitated permanent magnet (PM) and a supporting superconductor with superconducting coil, a control coil and a Hall sensor. The damping for the SMB with superconducting coil is compared with the SMB without superconducting coil. PD control is applied to the SMB and the damping characteristics are also discussed.

Small-Sized Wind-Light Complementary Power Generation System with Permanent Magnetic Levitation Technique

In this paper, permanent magnetic levitation technique is studied in the research of small-sized wind-light complementary power generation system. Radial and axial permanent magnetic levitation technology has been studied, and the over design is done based on these two kinds of technologies, which make the wind power generation get breeze starting. It lays a solid foundation to achieve the breeze power generation. The overall design of the important parts of the power generation system has also been put forward in this paper.

Design and Research of Industrial Permanent Magnetic Bearing

Because of that the permanent magnetic bearing (PMB) has the advantage of no wear, low cost and simple structure, the industrial design concept of PMB has been put forward in this paper. Radial and axial permanent magnetic levitation technology has been studied, and the aforementioned design is done based on these two kinds of technologies. During the experiments on the mechanical characteristics of PMBs, the capacity and stiffness of the bearings are researched.

Study on improving levitation stability from high frequency vibration for the application of a seismic isolation device

The stability of superconductor levitation is depending on the pinning force. However, when an external force such as the earthquake with a high magnitude higher than the pinning force is exerted, the levitated permanent magnet (PM) can become unstable and destroyed. In order to improve the stability of the levitation, a copper plate was inserted in between the HTS (high temperature superconductor) bulk and the PM. And the more stabilized levitation can be achieved by applying eddy current that is caused by PM and the copper plate.In this study, various arrangements of PM, the thickness of copper plate, the area and gap length between PM and the copper plate were carried out. The eddy current was greater in the arrangement where polarity was changed with parallel to a moving shaker than the arrangement where polarity was not changed. And also, the eddy current became greater as the gap length between the PM and copper plate decreased. The highest value of the eddy current was measured at a copper plate thickness of 5mm and a size of 80mm×80mm. From the eddy current experiments, a copper plate (80mm×80mm×5mm) inserted between the 7mm gap length of the HTS bulk and the PM was resulted in a higher stiffness value of 65% compared to no copper plate stiffness value.

Dependence of equilibrium height of a magnet on initial magnetization process in a high T _c superconducting levitation system

The equilibrium height (EH) of a levitated permanent magnet (PM) is investigated in an oscillation system composed of the PM and a high temperature superconductor (HTS). Two kinds of initial quasi-static magnetization processes are performed respectively, and then the EH is achieved after a damped vibration of the PM. A peak value of the EH, associated with a transitional magnetization height (TMH), is found for the first initial process. When the magnetization height (MH) is less than the TMH, the EH increases with the increasing of the MH nonlinearly. Otherwise the EH decreases linearly with the MH. For the second initial magnetization process a minimum value of the EH is also presented. The magnetic energy of the system is believed to be responsible for these two different dependences.

A novel permanent magnetic rail for HTS levitation propulsion system

The Halbach Array has a characteristic advantage that the spatial fundamental field is canceled on one side of the array while the field intensity on the other side is enhanced. So this array could be used in the design of high temperature superconducting permanent magnetic levitation rail to improve the surface magnetic field and levitation force. This paper compared the surface magnetic field of the Halbach Array rail and two conventional levitation rails at first. Then proposed the potential advantages of Halbach Array applied in permanent magnetic rail system. But the Halbach Array rail is mechanical instability. An novel improved Halbach Array rail is proposed in this paper. The new structure combined the advantages of traditional structure and Halbach Array structure, solved the problem of mechanical instability, and carried on the advantage of Halbach Array on the magnetic field distribution at the same time.

Numerical study of the influence of flux creep and of thermal effect on dynamic behaviour of magnetic levitation systems with a high-Tcsuperconductor using control volume method

This paper displays some simulation results of dynamic responses of the high-Tc superconductors (HTSC)-Permanent magnet (PM) levitation systems taking into account the influence of the flux creep phenomena and of the thermal effect. We focus on the establishment of a three-dimensional numerical code to solve the nonlinear and coupled equations. A new control volume method is proposed for the resolution of the partial derivative equations of the treaded physical phenomena. The influence is comprehensively displayed by comparing the predictions of dynamic responses of such systems in which the thermal effect in the superconductor is and is not taken into account. The electromagnetic and thermal coupling is ensured by an alternate algorithm. The thermal effect highlights the influence of the temperature on the value of the magnetic levitation force, levitation stabilization time and shows that the vibration center of levitated body had drifted downward.

Proposal of permanent magnet repulsive maglev transportation system: possibility of automobile with magnetic levitation

AbstractThis paper describes a maglev transportation system for automobiles. The track is an array of permanent magnet blocks, and the levitating body is the bedplate which consists of permanent magnet plates, propulsion coils, levitation coils, and guidance coils. The feature of this system is that an automobile equipped with the bedplate is free to approach into the track or to swerve from the track by using four wheels with the lift. The force acting on the levitating body is calculated on the assumption that each permanent magnet can be expressed as a surface current. From the calculation results, it is proven that an automobile of 4.35 m length, 1.8 m width, and 1700 kg weight can run at a speed of 500 km/h against the air resistance force of 3704 N on the condition that the battery has an output of 337.5 V and a capacity of 190 Ah. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 65– 76, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20491

The driving torque of a rotating levitated cylindrical permanent magnet above a superconductor

Due to the Meissner effect, a permanent magnet is levitated, when released above a high temperature superconductor. When there is an inhomogeneous temperature field around the magnet, the magnet might start to oscillate with increasing amplitude until it remains in a continuous rotation. A mathematical model for the described effect is presented which couples heat transfer and electromagnetic forces with the equation of motion, yielding to a multiphysics task. In a detailed analysis it is found, that the torque which drives the rotation of the magnet, is explicitly given in terms of Bessel functions and the Fourier coefficients of order zero and one of the temperature field of the surrounding air.

Proposal of Permanent Magnet Repulsive Maglev Transportation System-Possibility of Automobile with Magnetic Levitation-

This paper describes a maglev transportation system for automobile. The track is an array of permanent magnet blocks, and the levitating body is the bedplate which consists of permanent magnet plates, propulsion coils, levitation coils and guidance coils. The feature of this system is that the automobile equipped with the bedplate is free to approach into the track or to swerve from the track by using four wheels with the lift. The force acting on the levitating body is calculated on the assumption that each permanent magnet can be expressed as a surface current. From the calculation results, it is proven that the automobile of 4.35m length, 1.8m width and 1700kg weight can run at speed of 500km/h against the air resistance force of 3704N on the condition that the battery has an output of 337.5V and a capacity of 190Ah.

A novel permanent maglev impeller TAH: most requirements on blood pumps have been satisfied.

Based on the development of an impeller total artificial heart (TAH) (1987) and a permanent maglev (magnetic levitation) impeller pump (2002), as well as a patented magnetic bearing and magnetic spring (1996), a novel permanent maglev impeller TAH has been developed. The device consists of a rotor and a stator. The rotor is driven radially. Two impellers with different dimensions are fixed at both the ends of the rotor. The levitation of the rotor is achieved by using two permanent magnetic bearings, which have double function: radial bearing and axial spring. As the rotor rotates at a periodic changing speed, two pumps deliver the pulsatile flow synchronously. The volume balance between the two pumps is realized due to self-modulation property of the impeller pumps, without need for detection and control. Because the hemo-dynamic force acting on the left impeller is larger than that on the right impeller, and this force during systole is larger than that during diastole, the rotor reciprocates axially once a cycle. This is beneficial to prevent the thrombosis in the pump. Furthermore, a small flow via the gap between stator and rotor from left pump into right pump comes to a full washout in the motor and the pumps. Therefore, it seems neither mechanical wear nor thrombosis could occur. The previously developed prototype impeller TAH had demonstrated that it could operate in animal experiments indefinitely, if the bearing would not fail to work. Expectantly, this novel permanent magnetic levitation impeller TAH with simplicity, implantability, pulsatility, compatibility and durability has satisfied the most requirements on blood pumps and will have more extensive applications in experiments and clinics.