Repulsive Magnetic Levitation System Research Articles

Stabilization of a Magnetic Repulsive Levitation Flywheel System Using a High-Efficiency Superconducting Magnetic Bearing

In this study, we developed a superconducting magnetic bearing using a permanent repulsive magnet. A repulsive magnetic levitation system with a permanent magnet can generate a strong levitation force in the absence of a power supply. However, it is unstable, except in the direction of repulsion. In contrast, superconducting magnetic bearings can generate a restoring force in all directions by utilizing the magnetic flux pinning property of the superconductors. Therefore, we constructed a superconducting magnetic bearing (SMB), which is stable along all axes without control, and has a strong axial levitation force, by combining a repulsive-type magnetic levitation system and a superconducting magnetic levitation system. We also reduced the amount of HTS used for the SMB and proposed an efficient method of using HTS. Furthermore, a driving test of the flywheel incorporating the SMB was conducted to verify the characteristics of the SMB. The experiment confirmed that the flywheel could overcome the resonance and drive the flywheel. In the drive experiment, the flywheel was driven up to 10,000 rpm.

Adaptive Control of Repulsive Magnetic Levitation System

Adaptive Control of Repulsive Magnetic Levitation System

Control conmutado para un sistema de levitación magnética con atascamiento-deslizamiento

Magnetic levitation systems can be used in many applications such as precise positioning. Repulsive configurations are open-loop stable and offer other interesting characteristics. However, these applications may present stick-slip effects due to the friction forces. The combination of the highly non-linear magnetic forces and the stick-slip effects result in a complex control problem. This article presents the identification, model analysis and control system design for an experimental repulsive magnetic levitation system. The design is based on the principles of state feedback linearization. In previous reports it was shown that the performance of feedback linearization control of similar devices is degraded by the parameter uncertainty introduced by the friction. In this work, the performance of the feedback linearization control is improved by adding an outer-loop linear controller with integral action. This controller was designed according to classical frequency analysis. Experimental results show better transient responses and low steady state errors. Nevertheless, the integral action and the friction force increase the stick-slip oscillations. Stick-slip motion is eliminated through a switching control strategy based on the experimental characterization of the stick-slip sliding surface. The resulting control scheme allows preserving the low steady state error of the integral control law and eliminates the stick-slip motion. This is accomplished through a relatively simple controller when compared with previous reports. Experimental results show the effectiveness of the proposed scheme.

504 反発型磁気浮上装置のセルフパワード・アクティブ振動制御

磁気浮上系は非接触なため、摩擦、磨耗、騒音の心配がない利点を持ち、磁気軸受け、クリーン性を要する環境の搬送装置、高速の磁気浮上車などに適用されている.反発型の磁気浮上系は静的には安定であるが、十分な散逸エネルギが得られないため、動的な安定性はあまり期待できない.コイルをアクチュエータとして扱うアクティブ制御は、パッシブより良好な制振特性を示すが、アクティブ制御は外部エネルギを消費する欠点がある.また、アクティブ制御を行う際に、エネルギを回生し、その回生したエネルギを用いて制御を行う、セルフパワード・アクティブ制御が提案されている.本研究では永久磁石反発型の一自由度系モデルの装置を用い、アクティブ制御の外部エネルギに代わり、アクチュエータから電磁気的に回生した振動エネルギを使用する. 実験装置には、リニアガイドに沿って上下運動をすることができる浮上体に、コイルが取り付けてある.そのコイルがアクティブ制御を行うアクチュエータとエネルギ回生を行うジェネレータの役割をする.制御系設計では、最適制御理論を用いた.浮上体の振動を抑えるために浮上体の速度に重みをかけ、地面との接触を避けるために相対変位に重みをかけた評価関数を用いた.セルフパワード・アクティブ制御において、コイルに流れる電流を目標電流に近づけるため、モードを切り替えている.各モードには、エネルギ回生モード、ブレーキモード、力行モードがある.図A1のコイルオープンとセルフパワード・アクティブ制御の浮上体絶対変位のパワースペクトル密度を比較すると、セルフパワード・アクティブ制御を行ったときの浮上体絶対変位が抑えられていることがわかる.また、図A2のコイルオープン、アクティブ制御、セルフパワード・アクティブ制御の浮上体絶対変位のRMS値からも、同様に、セルフパワード・アクティブ制御時に抑えられていることがわかる.永久磁石反発型磁気浮上装置を用い、ランダム波を外乱として加えたときのセルフパワード・アクティブ振動制御を行った結果、セルフパワード・アクティブ制御の動的安定性をコイルオープン時より向上させることができた.さらに外部からのエネルギの供給をせずに、アクティブ制御に近い制振特性も得られることを示すことができた.

Repulsive Magnetic Levitation Systems Using Motion Control of Magnets.

Repulsive Magnetic Levitation Systems Using Motion Control of Magnets.

Study on the Dynamic Stability of Repulsive Magnetic Levitation Systems (Optimal Control of Active Secondary Suspension).

Repulsive magnetic levitation systems for vehicle suspensions are statically stable but dynamically of zero or low damping characteristics. In paticular, it is reported that electrodynamic suspensions have negative damping in some operating conditions. In this paper, an active suspension is applied to the secondary suspension of the zero-damping magnetic levitation system in order to improve the dynamic stability of both the car body and truck. The active suspension with a pneumatic actuator is designed by optimal regulator theory. The kinetic energy and the potential energy of both the car body and truck are evaluated according to an evaluation criterion. The two-degrees-of-freedom suspension model of this MAGLEV system is analyzed theoretically and compared with the experimental results. The theoretical analysis and experimental results show that the dynamic stability is much improved by the active secondary suspension.

Study on Dynamic Stability of Repulsive Magnetic Levitation System. 2nd Report. Vibration Control Effect of Active Secondary Suspension.

For high speed magnetically levitated (MAGLEV) vehicle systems significant attention must be given to the secondary suspension as it determines the ride comfort and has great influence on the vehicle stabilty. This paper analyzes theoretically and experimentally the performance of an active secondary suspension on the ride quality and running stability of repulsive MAGLEV vehicles. The suspension is equipped with a microcomputer controlled pneumatic actuator and it is governed by an optimal control approach. Two measures of performance have been analyzed: car body vertical acceleration (ride comfort) and truck-guideway gap variations (running stability). The experimental results show the performance improvement obtainable with an active secondary suspension and sufficiently agree with the theoretical simulation.

Dynamic Stability of Repulsive Magnetic Levitation System. 3rd Report. Optimal Control of Active Primary Suspension.

Magnetically levitated (MAGLEV) vehicle systems have been studied as the future high-speed transportation. It is especially important to investigate the dynamic characteristics for running stability, safety and ride quality at high speeds. This paper deals with the vibration control problem of a two-degree-of-freedom vehicle-suspension model of repulsive MAGLEV systems; Although the repulsive MAGLEV system is inherently stable, the damping force is not large enough to suppress the vibration excited by guideway irregularity. In order to improve the vibration characteristics, there are two approaches; one 6f them is through secondary suspension design and the other, primary suspension design. The first approach gives a limit of vibration control because of the existence of an invariant point in the frequency response of car-body acceleration. This paper investigates the second approach, that is, direct magnetic force control of the MAGLEV systems. For this purpose the primary suspension is designed as a hybrid magnet configuration of a permanent magnet and an additional electromagnet of which the current is optimally controlled by LQG theory. The experimental and theoretical results show that the car body and levitation gap vibrations are significantly improved with the additional control circuit.

Study on dynamic stability of repulsive magnetic levitation system. 1st Report. Optimal control of active secondary suspension.

Repulsive magnetic levitation systems for vehicle suspensions are statically stable but dynamically of zero-or low-damping characteristics. Especially it is reported that electrodynamic suspensions have negative damping in some operating condition. In this paper, an active suspension is applied to the secondary suspension of the zero-damping magnetic levitation system in order to improve the dynamic stability of both the car body and the truck. The active suspension with a pneumatic actuator is designed by optimal regulator theory. The kinetic energy and the potential energy of both the car body and the truck are evaluated in an evaluation criterion. The two degress of freedom suspension model of this maglev system is analyzed theoretically and compared with the experimental results. The theoretical analysis and experimental results show that the dynamic stability is much improved by the active secondary suspension.

Thick Rectangular Guideway Interactions in Electrodynamic Repulsive Magnetic Levitation Systems

The electrodynamic interaction of a superconducting magnet, moving over a thick continuous rectangular conducting guideway, is analyzed as an E.M.-field, boundary-value problem. The guideway eddy-current is assumed to be the sum of weighted eigen-functions of Bullard's equation. The magnetic field intensity of the eddy-current is synthesized by superposition of known Laplace's solutions associated with planar slices of the eddy-current. Electrodynamic coupling between the superconducting magnet and the guideway is established by insisting that the Laplace's solutions must be annulled inside the guideway, as only Bullard's solutions are admissible.

Thick Rectangular Guideway Interactions in Electrodynamic Repulsive Magnetic Levitation Systems

Thick Rectangular Guideway Interactions in Electrodynamic Repulsive Magnetic Levitation Systems

Dynamic circuit and Fourier series methods for moment calculation in electrodynamic repulsive magnetic levitation systems

A general theory of moments for electrodynamic magnetic levitation systems has been developed using double Fourier series and dynamic circuit principles. Both employ Parseval's theorem using either wave constant derivatives or the polar waveconstant principle of the Fourier-Bessel/double Fourier series equivalence. A method for calculating angular derivatives of moments and forces is explained, and for all of these methods comparisons are made with experimental results obtained for single and split rail configurations. Extensions of dynamic circuit theory for tilted nonflat and circular magnets are also explained.

STATIC AND DYNAMIC PERFORMANCE OF ELECTRODYNAMIC (REPULSION) LEVITATION SYSTEMS (EDS)

ABSTRACT Based on a new simplified approach this paper shows theoretically that the sheet secondary is net inferior to discrete secondary in repulsive magnetic levitation systems. The dynamic behavior is then explored and the control coil data are obtained. Numerical example of practical interest are also provided to get a feeling of magnitudes.

Force Transients at Guideway Butt Joints in Repulsive Magnetic Levitation System

To provide for thermal expansion, the guideway for the repulsive levitation of high-speed ground transport would be jointed. The effect of butt joints on the force components is analysed by the dynamic circuit theory. Predicted results show very good agreement with measurements.

Passive and active damper winding for the repulsive magnetic levitation system

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.

A dynamic circuit theory of the repulsive magnetic levitation system

A generalized machine theory formulation is derived for the repulsive magnetic levitation system consisting of flat superconducting magnets interacting with flat finite width strip conducting guideways. Experimental verifications are presented.

Electromechanical stiffness and damping coefficients in the repulsive magnetic levitation system

The electromechanical stiffness and damping coefficient matrices for three translational degrees of freedom are derived for the repulsive levitation system consisting of a single superconducting magnet interacting with a finite width sheet guideway. The persistent node (constant flux linkage) is assumed. The results of this study provide the data for stability and ride quality analysis. The methodology can be extended to multi-magnet systems including active damping coils.

Transients and oscillations in the repulsive magnetic levitation system

A repulsive levitation system consisting of a finite number of vehicle coils and an infinite number of short circuited coils on the ground is treated with two degrees of freedom. All self- and mutual inductances are calculated three-dimensionally. A set of seven simultanious differential- and integral equations is obtained, which is solved numerically. As an example, a nullflux system for a high speed train with 150 and 500 km/h has been investigated. At the steady state, the losses, lift- and traction forces and their pulsations have been calculated. Transients due to sudden wind forces or track irregularities are also dealt with. The damping of the vehicle oscillations due to disturbances becomes poorer with increasing vehicle speed.

Electromechanical dynamics in superconducting levitation systems

The theoretical analyses of the repulsive magnetic levitation system for high-speed ground transport have so far treated only steady-state equilibrium conditions. This paper presents an experimentally verified dynamic circuit theory formulation which can cope will electromechanical time transients as well.