Donald M. Rote

Review of dynamic stability of repulsive-force maglev suspension systems

Vehicle dynamics and the need to satisfy ride quality requirements have long been recognized as crucial to the commercial success of passenger-carrying transportation systems. Design concepts for maglev systems are no exception. Early maglev investigators and designers were well aware of the importance of ride quality and took care to ensure that their designs would meet acceptable ride quality standards. In contrast, the dynamic stability of electrodynamic suspension (EDS) systems, which has obvious implications for system safety and cost as well as for ride quality, has not received nearly as much attention. Because of the well-known under-damped nature of EDS suspension systems and the observation of instabilities in laboratory-scale model systems, it is prudent to develop a better understanding of vehicle stability characteristics. The work reported in this was undertaken with the intention of summarizing information that has been accumulated worldwide and that is relevant to dynamic stability of repulsive-force maglev suspension systems, assimilating that information, and gaining an understanding of the factors that influence that stability. Included in the paper is a discussion and comparison of results acquired from some representative tests of large-scale vehicles on linear test tracks, together with analytical and laboratory-scale investigations of stability and dynamics of EDS systems. This paper will also summarize the R and D activities at Argonne National Laboratory (ANL) since 1991 to study the nature of the forces that are operative in an EDS system and the dynamic stability of such systems.

Applications of the dynamic circuit theory to Maglev suspension systems

The applications of dynamic circuit theory to electrodynamic suspension (EDS) systems are discussed. Emphasis is placed on the loop-shaped coil and the figure-eight-shaped null-flux coil suspension systems. Mathematical models, including very general force expressions that can be used for the development of computer codes, are provided for each of these suspension systems. The general applications and advantages of the dynamic circuit model are summarized. The transient and dynamic analysis and computer simulation of Maglev systems are emphasized. The method can be applied to many EDS Maglev design concepts. It is also suited for the computation of the performance of Maglev propulsion systems. Numerical examples are presented to demonstrate the capability of the model. >

Analysis of the combined Maglev levitation, propulsion, and guidance system

An analysis of a Japanese Maglev system that uses only one set of coils in the guideway for combined levitation, propulsion, and guidance functions is presented. This preliminary study, using the dynamic circuit approach, indicates that the system is very promising. >

Investigation of the stability of AC repulsive-force levitation systems for low-speed maglev

Discusses the stability of an AC induction levitation system, focusing on the analysis and optimum design of the secondary conductor. Several improved secondary conductor geometries are considered. A theoretical model with numerical results, as well as experimental observations and data are presented. Theoretical and experimental results indicate that only marginal stability can be achieved with a single-plate secondary conductor. Modifications of the single plate can enhance its stability at rest, but this design suffers from longitudinal instabilities when propelled. It is concluded that a double-plate secondary conductor is stable in all six degrees of freedom. >

Magnetic Damping For Maglev

Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.

Double-row loop-coil configuration for EDS maglev suspension, guidance, and electromagnetic guideway directional switching

A new suspension and guidance configuration for a high speed, electrodynamic suspension (EDS) maglev system is discussed. The configuration can also be used to develop an electromagnetic guideway directional switch. The performance of the system is predicted using the dynamic circuit model. General expressions of the magnetic forces based on the harmonic approximation are obtained. The principle of the electromagnetic guideway directional switch for the EDS maglev system is discussed. >

Magnetohydrodynamic stability in the electromagnetic levitation of horizontal molten‐metal sheets

High‐frequency electromagnetic (EM) fields are investigated for the levitation of thin horizontal sheets of liquid metal. A magnetic configuration is analyzed in which inductance stabilization provides global stability and magnetic flux compression provides local stability. Stability analysis indicates that frequencies greater than about 24 kHz are desirable to stably levitate 6 mm thick steel. For stability in systems without active feedback, a conducting screen is required below the metal, with a gap between the screen and the molten metal of no more than twice the metal thickness. Experiments in which 10 kHz EM fields were used to statically levitate sheets of molten tin indicate that dominant magnetohydrodynamic instabilities are of the Rayleigh–Taylor type and correspond to theory.

Forces on a magnet moving past figure-eight coils

The lift, drag, and guidance forces acting on a permanent magnet are measured as different arrays of figure-eight (null-flux) coils pass under the magnet. The experimental results are in good agreement with the predictions of dynamic circuit theory, which can be used to investigate other coil arrays. >

Dynamic Stability of Maglev Systems

Because dynamic instability is not acceptable for any commercial maglev systems, it is important to consider this phenomenon in the development of all maglev systems. This study considers the stability of maglev systems based on experimental data, scoping calculations, and simple mathematical models. Divergence and flutter are obtained for coupled vibration of a three-degree-of-freedom maglev vehicle on a guideway consisting of double L-shaped aluminum segments attached to a rotating wheel. The theory and analysis developed in this study identifies basic stability characteristics and future research needs of maglev systems.

Survey of foreign maglev systems

Magnetic levitation (maglev) transportation systems represent an innovative technology that promises to provide pollution-free, contact-free, high-speed ground transportation for the twenty-first century. Great interest in maglev systems has been developing in the United States over the past two years under the auspices of the US National Maglev Initiative. The objective of the survey presented in this report is to provide the US maglev community with information on various maglev concepts that were developed in foreign countries over the past two decades. The main maglev systems included in the survey are the German Transrapid series and the M-Bahn, the Japanese HSST and MLU series, and the British Birmingham. Each maglev system is introduced and discussed according to its type, historical development, unique features, current status, and future prospects. Advantages and disadvantages of each system are briefly noted.