We present a two-dimensional complex steady-state finite-element method for calculating the lift and thrust or breaking forces created when a magnetic rotor is translationally moved and rotated over a conducting sheet. The method replaces the magnetic rotor with an equivalent current sheet by equating the current sheet's and magnet rotor's magnetic vector potentials. We validate the steady-state method by comparing the forces with transient finite-element models. The utility of this steady-state model is that it enables a study of the effects of parameter changes for such a machine to be undertaken rapidly.

Calculating the Forces Created by an Electrodynamic Wheel Using a 2-D Steady-State Finite-Element Method

General relations and limitations pertinent to the design of an inductive magnetic suspension system are derived. It is shown that in order to reduce magnetic drag we must increase the vehicle field and decrease the guideway currents. But this then produces a stiff suspension unless we are willing to increase guideway cost. Reasonable and consistent design objectives are shown to be: vehicle natural frequency for heave≃1 Hz without secondary suspension; suspension power lossessime;10 kW/ton (L/D=120 at 270 mi/h); aluminum requirements≃80 kg/m for a dual guideway. It was shown to be theoretically possible to operate at arbitrarily low speeds by using either a superconducting guideway or a feedback control system for short distances near terminals. Between terminals the guideway might resemble a parallel-wire transmission line with a thin conducting sheet between the wires. The design of an active-guideway linear synchronous motor is discussed and shown to be capable of supplying 5 MW of power at efficiencies of about 85 percent and a power factor of 0.5. For a dual guideway the armature windings require about 40 kg/m of aluminum, but no steel. The total cost of the maglev portion of a 120 m/s (268 mi/h) high-speed ground transportation system is estimated to be about 1 million dollars/km, with at least half of this related to propulsion and power distribution and control. If speed is reduced to 90 m/s (202 mi/h), substantial economies are possible.

Design principles for magnetic levitation

The braking forces acting on a thick conducting disc rotating in the field of rectangular electromagnets are examined. The analysis is based on the solution of quasi-one-dimensional vector potential in the plate and airgap regions of the device. Finite thickness of the plate is taken into account explicitly in deriving the general expression for the braking force. This expression is shown to reduce to the conventional induction motor characteristic in the thin plate limit and a simple original expression is presented for the calculation of braking forces in the skin-effect region.

Theory of eddy-current brakes with thick rotating disc

A status report on progress toward the development of a magnetic levitation and propulsion system for mass transportation is presented. It summarizes important results and provides a bibliography for further study. Emphasis is placed on various aspects of different magnetic structures which have been proposed for this application.

Magnetic levitation and propulsion, 1975

The linear travelling-wave induction problem

An approach to the analysis of linear motors, based on the Fitzgerald superpotential is outlined. The usefulness of the approach is demonstrated in calculations of the fields, the streamline pattern, and the performance characteristics of some versions of the linear motor. Analysis of the streamline pattern brings out, in turn, the influence of the end effects.

D. Schieber

Papers

Principles of operation of linear induction devices