Passive Magnetic Levitation Research Articles

Hyperloop New Mode of Transportation

Today conventional mode of transportation is rail, road, water, and air. These modes of transport are relatively slow and expensive or a combination of relatively slow and expensive. Hyper loop is latest mode of transportation which is fast and inexpensive to change the pattern of transportation. Similar to Linux, hyper loop is also open and unique design concept. By bringing this concept to reality, it will help people to travel from one city to another city in a very small time and also at a low cost. The hyper loop capsule would accelerate with the help of linear electric motor and traverse through the tube at a high speed. By using passive magnetic levitation or air bearing, capsule will run above their track. Hyper loop consists of a low-pressure tube with capsules that are travelled at low and high speed throughout the length of the tube. The capsules are supported with the help of cushion of air. To accelerate the capsules the magnetic linear accelerator is fitted at various stations on the hyperloop tube. To enter and exit the passengers the passage may be left either at the end of the tube or branches along the tube length. Let's see how the hyperloop change mode of transportation.

Modeling and experimental validation of electrodynamic maglev systems

The pursuit of novel, environmentally friendly solutions for mobility and transportation has been a relevant area of technical and scientific progress in recent years. In this regard, the Hyperloop concept is a novel solution for sustainable transportation of people and goods at high speed. The electrodynamic levitation system in Hyperloop represents a key enabling technology. Nevertheless, its unstable nature is crucial and requires proper analysis and understanding. This paper proposes the experimental stabilization of electrodynamic maglev systems by means of passive components. A downscaled test setup is used to validate the numerical models that govern passive maglev systems. Setups for quasi-static and dynamic testing are proposed. The former experiments lead to model parameter tuning. The latter reproduce unstable behavior and assist in testing a stabilization method. Results in the time and frequency domains are used to analyze the system response and validate the proposed approach.

Combined Propulsion and Levitation Control for Maglev/Hyperloop Systems Utilizing Asymmetric Double-Sided Linear Induction Motors

This article presents a new method for combined levitation and propulsion control in maglev/Hyperloop systems by selectively applying AC and DC modes of operation to a group of asymmetric double-sided linear induction motors (ADSLIMs). Although adjusting the AC current magnitude of lower and upper primary windings in ADSLIMs allows simultaneous control of thrust and lift forces, the limitation of this current balancing technique prohibits them from producing a high lift force while operating with low thrust force. To overcome this limitation and to simultaneously control the thrust and lift forces of the ADSLIMs with high efficiency under different operating conditions, a combination of AC and DC modes of operation is proposed. AC mode of operation consists of feeding different AC current amplitudes to the upper and lower ADSLIM primary windings to produce and control the required thrust and lift forces. The DC mode of operation consists of controlling one or several ADSLIMs to operate with DC excitation to realize the desired lift force at lower thrusts which otherwise cannot be achieved by operating in AC mode alone. The concept of the new combined control strategy is studied using two-dimensional finite element (FE) electromagnetic simulations and compared with an Inductrack permanent magnet (PM) based passive magnetic levitation system.

Analysis and Design of a Novel Magnetic Levitation Gravity Compensator With Low Passive Force Variation in a Large Vertical Displacement

This paper presents a novel magnetic levitation gravity compensator and its design philosophy by which the nearly constant levitation force performance within a relatively large vertical displacement can be easily obtained. Generally, the absolute levitation is desired in many ultraprecision positioning systems, because the vibration disturbance can be effectively isolated. However, it is very difficult to obtain the low stiffness performance due to the serious nonlinearity of the passive force between two permanent magnets. The proposed magnetic levitation gravity compensator is combined with two passive magnetic levitation units owning the opposite levitation force characteristics. Based on the design principle of stiffness counteraction, the two levitation forces from the two units are superimposed but the resultant levitation force variation is very low. The stiffness counteraction effect is finally verified by experiments. The prototype testing data shows that the maximum levitation force variation of the proposed magnetic levitation gravity compensator within ±5 mm is only 0.72 N, which is 2.4% of the rated passive levitation force 30 N.

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.

Research on typical topologies of a tubular horizontal-gap passive magnetic levitation vibration isolator

Magnetic levitation vibration isolators have attracted more and more attention in the field of high-precision measuring and machining equipment. In this paper, we describe a tubular horizontal-gap passive magnetic levitation vibration isolator. Four typical topologies of the tubular horizontal-gap passive magnetic levitation vibration isolator are proposed. The analytical expression of magnetic force is derived. The relationship between levitation force, force density, force ripple and major structural parameters are analysed by finite element method, which is conductive to the design and optimization of the tubular horizontal-gap passive magnetic levitation vibration isolator. The force characteristics of different topologies of the tubular horizontal-gap passive magnetic levitation vibration isolator are compared and evaluated from the aspect of force density, force ripple and manufacturability. In comparison with conventional passive magnetic levitation vibration isolators, the proposed tubular horizontal-gap passive magnetic levitation vibration isolator shows advantage in higher force density.

피치 운동을 고려한 자기부상 수동형 이송자 제어

피치 운동을 고려한 자기부상 수동형 이송자 제어

Electromagnetic and Mechanical Characteristics Analysis of a Flat-Type Vertical-Gap Passive Magnetic Levitation Vibration Isolator

In this paper, we describe a flat-type vertical-gap passive magnetic levitation vibration isolator (FVPMLVI) for active vibration isolation system (AVIS). A dual-stator scheme and a special stator magnet array are adopted in the proposed FVPMLVI, which has the effect of decreasing its natural frequency, and this enhances the vibration isolation capability of the FVPMLVI. The structure, operating principle, analytical model, and electromagnetic and mechanical characteristics of the FVPMLVI are investigated. The relationship between the force characteristics (levitation force, horizontal force, force ripple, and force density) and major structural parameters (width and thickness of stator and mover magnets) is analyzed by finite element method. The experiment result is in good agreement with the theoretical analysis.

과구동 자기부상 무전원 트레이의 부상제어 전략 및 자세제어 알고리즘

과구동 자기부상 무전원 트레이의 부상제어 전략 및 자세제어 알고리즘

Design and control of a passive magnetic levitation carrier system

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.

Research on a Low Stiffness Passive Magnetic Levitation Gravity Compensation System with Opposite Stiffness Cancellation

In the nanopositioning system, such as the wafer stage in a lithography machine, vibration isolation is applied to decrease the influence of the lower basic frame on the upper positioning system. At present, the combination of passive gravity compensation with magnetic force and active stabilization control using linear actuators is a potential solution for vibration isolation. In this paper, an opposite stiffness cancellation method which can be used to decrease the vertical stiffness of a passive gravity compensation system is proposed. By comparison, the new passive gravity compensation system has less stiffness than that of the conventional structure. Lastly, a prototype is manufactured and tested.

Controller design with high fidelity model for a passive maglev tray system

Usually, in controller design for maglev systems, only the dynamics of the magnet and the levitating object are modeled. However, reference frames, such as rails for maglev trains or magnet frames for a maglev tray system, are assumed as rigid bodies even though they have compliances. This is because the modeling of reference frames based on their design is not simple as the modeling of magnets or levitating objects. Therefore, the compliances of the reference frames are implicitly considered during the controller tuning process. Undoubtedly, controllers designed with better fidelity of system model will show better performance. This study presents an experimental way of achieving a model of a reference frame through impact tests and discusses the benefits of having a higher fidelity model in control design. The exemplary system is a passive maglev tray. Least Quadratic Regulator (LQR) control design is used to show the benefits of having a higher fidelity model. To verify the controllers in several conditions, the passive maglev tray system is designed and manufactured. Through several tests with several conditions, we will provide some suggestions for controller design of maglev systems.

Comparisons of Hydraulic Performance in Permanent Maglev Pump for Water-Jet Propulsion

The operation of water-jet propulsion can generate nonuniform inflow that may be detrimental to the performance of the water-jets. To reduce disadvantages of the nonuniform inflow, a rim-driven water-jet propulsion was designed depending on the technology of passive magnetic levitation. Insufficient understanding of large performance deviations between the normal water-jets (shaft) and permanent maglev water-jets (shaftless) is a major problem in this paper. CFD was directly adopted in the feasibility and superiority of permanent maglev water-jets. Comparison and discussion of the hydraulic performance were carried out. The shaftless duct firstly has a drop in hydraulic losses ( K1), since it effectively avoids the formation and evolution of the instability secondary vortex by the normalized helicity analysis. Then, the shaftless intake duct improves the inflow field of the water-jet pump, with consequencing the drop in the backflow and blocking on the blade shroud. So that the shaftless water-jet pump delivers higher flow rate and head to the propulsion than the shaft. Eventually, not only can the shaftless model increase the thrust and efficiency, but it has the ability to extend the working range and broaden the high efficiency region as well.

Dynamics and stability of rigid rotors levitated by passive cylinder-magnet bearings and driven/supported axially by pointwise contact clutch

A stable rotor—supported laterally by passive magnetic bearings and longitudinally by magnetic forces and a clutch—loses suddenly its contact to the clutch and executes abruptly longitudinal movements away from its original equilibrium position as a result of small increases in angular velocity. Such an abrupt unstable behaviour and its reasons are thoroughly theoretically as well as experimentally investigated in this work. In this context, this paper gives theoretical as well as experimental contributions to the problem of two dimensional passive magnetic levitation and one dimensional pointwise contact stability dictated by mechanical–magnetic interaction. Load capacity and stiffness of passive multicylinder magnetic bearings (MCMB) are thoroughly investigated using two theoretical approaches followed by experimental validation. The contact dynamics between the clutch and the rotor supported by MCMB using several configurations of magnet distribution are described based on an accurate nonlinear model able to reliably reproduce the rotor-bearing dynamic behaviour. Such investigations lead to: (a) clear physical explanation about the reasons for the rotor's unstable behaviour, losing its contact to the clutch and (b) an accurate prediction of the threshold of stability based on the nonlinear rotor-bearing model, i.e. maximum angular velocity before the rotor misses its contact to the clutch as a function of rotor, bearing and clutch design parameters.

Passive Magnetic Levitation of Rotors on Axial Electrodynamic Bearings

The present paper presents a new modeling approach for null flux axial electrodynamic bearings. Such approach allows defining stability bounds for rotors supported with this type of passive magnetic suspension. The linearized models are developed using the bond graph methodology to better understand the multiphysics nature of the magnetic suspension. The adoption of complex variables together with the bond graph formalism is introduced in order to reduce the complexity of the system's equations. Rules for the use of this approach are established and demonstrated.

Development of Magnetic Bearing System for a New Third-Generation Blood Pump

A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38 mm, thickness of 0.88 mm, and resolution of 5 µm. The BLDC motor compartment was designed to have an outer diameter of 20 mm, length of 28.75 mm, and power of 4.5 W. It exhibited a torque of 8.6 mNm at 5000 rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22 mm and a length of 97 mm. The prototype exhibited sufficient levitation performance in the stop state and the rotation state with a gap of 0.2 mm between the rotor and the stator. The system had a steady position error of 0.01 µm in the stop state and a position error of 0.02 µm at a rotational speed of 5000 rpm; the current consumption rates were 0.15 A and 0.17 A in the stop state and the rotation state, respectively. In summary, we developed and evaluated a unique magnetic bearing system with an integrated motor. We believe that our design will be an important basis for the further development of the design of an entire third-generation blood pump system.

Applications of Permanent Maglev Bearing in Heart Pumps and Turbine Machine

Earnshaw's theorem (1839) stated that no stationary object made of magnets in a fixed configuration can be held in stable equilibrium by any combination of static magnetic or gravitational forces. What will happen by a moving body like a rotating passive magnetic levitator? Nobody has given an answer until now. The author applied a self-made passive magnetic bearing to radial pump and turbine machine and found that if the rotating speed could be higher than a critical value, 3250 rpm for a pump and 1800 rpm for a turbine, the rotors would be disaffiliated from stators and keep the rotation stable. It seems that the fast rotating levitator has a so-called “Gyroeffect” which makes the passive maglev rotator stable. These results have extended Earnshaw's theorem from static to dynamic equilibrium. In static state or by a speed lower than critical value, the passive maglev rotator cannot keep rotation stable; if the rotating speed is higher than critical speed, the passive magnetic levitator will have Gyroeffect and thereby stabilize its rotation.

A passive Maglev vehicle with self-regulating aerostatic-aerodynamic pads

The levitation of an operating Maglev is obtained with electromagnets EMS or superconducting materials SMS. In 2003, we designed a simpler Maglev PMS, which is levitated by permanent-magnet-aluminium circuits to remove the lateral instability of permanent magnets. In this paper, we show how to increase the side stability of this Maglev using lateral aerostatic-aerodynamic pivoted pads, arranged in the gap slide-guide. The air impacts the head of the pads giving a high aerostatic lift, which is added to the aerodynamic lift. The pads self-regulate their slope, thus increasing their lift as external forces increase.

Contact-free Two Dimensional Micro-displacement Actuation by Using Diamagnetic Graphite

Diamagnetic graphite (Pyrolytic graphite: PG) plate carries out passive magnetic levitation above high magnetic field without cooling down. By applying this phenomenon, the authors designed a contact-free two dimensional micro positioning model using PG plate and two dimensional (2D) Halbach permanent magnet (PM) array. In this model, the PG plate motion is performed with change in the surrounding magnetic field, which is provided by approaching a small PM piece. And as far as its keeping position, it does not require supplying electrical power. Recently, precise micro motion control of PG plate above 2D Halbach PM array was realized. For nano-scale precise motion control, currently, improving magnetic stiffness of PG plate has performed. This paper presents the result of improvement of magnetic stiffness and more precise motion of PG plate.

A New Passive Maglev System Based on Eddy Current Stabilization

In this paper, a new passive maglev system is presented that is capable to levitate at a short distance from a dedicated guide. The magnetic suspension is assured by the repulsion of proper shaped permanent magnets that are present both on the fixed guide and on the moving suspended part. The presence of a conductive (aluminum) sheet that surrounds the magnets on the guide allows to overcome the intrinsic instability of the system when the suspended part is in relative motion with respect to the guide. The motional induced electric currents on the sheet interact with the magnets of the mover producing a stabilizing force. The detailed structure of the proposed system is described and the main results of the simulations by means of a hybrid electromagnetic FEM-MOM code coupled with the equation of motion of the rigid body are shown and commented.