An investigation into the use of electrodynamic wheels for high-speed ground transportation
Abstract
The goal of this thesis has been to investigate whether a very low cost and efficient form of high-speed maglev (magnetic levitation) ground transportation is feasible. The thesis has focused on studying an integrated method of creating the maglev forces using a Halbach magnet rotor, termed an electrodynamic wheel. When magnets are electromechanically rotated over a conductive, non-magnetic, guideway currents are induced that can simultaneously create lift and thrust forces. By using a flat split-sheet guideway topology additional lateral re-centering forces can also be created. The use of magnets circumvents any low power factor issues and enables a relatively high lift-to-weight ratio to be attained in comparison to using windings. An equivalent 2D finite element current sheet model was developed that enabled both the high-speed rotational and translational motion of a Halbach rotor to be simulated in steady-state. Using this model, a 2D analysis of the parameters that influence the performance of the electrodynamic wheel, when using a flat sheet guideway, was conducted. In particular, it was shown that increasing the number of rotor poles and using multiple electrodynamic wheels in series can improve the thrust efficiency. Two 3D finite element models were developed in order to determine the 3D characteristics of the electrodynamic wheel when rotated over a split-sheet guideway. The first models the rotating Halbach rotor fields using a fictitious complex magnetic charge boundary condition. While the second analytically models the Halbach rotor fields and couples their effect on the moving conductive guideway via boundary conditions. The conductive and non-conductive regions were formulated using the magnetic vector and scalar potential respectively. Using these models it is shown that the wheel width has an important influence on the lift-to-weight ratio and that actively turning the wheel about the vertical axis can increase the lateral restorative forces. The numerical models were experimentally verified by measuring the forces created when a 0.1m diameter Halbach rotor was rotated over a 1.2m diameter split-sheet guideway wheel. The simultaneously created lift, thrust and lateral forces were measured using 10 load cells. Good agreement between the experimental and calculated forces has been obtained.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- December 2007
- Bibcode:
- 2007PhDT........87B