Force and Torque Model for a Novel Electrodynamic Suspension Reaction Sphere

What is it about?

This study presents a force and torque model utilising transfer-matrix theory for a novel electrodynamic suspension reaction sphere (EDSRS), which features a compact structure and low cost. A motor in the EDSRS is unfolded along the directions of the circumference and the arc of the stator iron core, then it can be regarded as a non-back-iron linear induction motor (NBILIM) with infinite length in the longitudinal direction. The NBILIM is simplified and extended by arranging infinite duplicates side by side along the transverse direction, constructing an extended simplified linear induction motor (ESLIM). Applying the transfer-matrix theory to each layer of the ESLIM, the relationship between the magnetic fields at two boundaries is obtained, and corresponding boundary conditions are presented. An analytical model is derived based on the magnetic field. Furthermore, the errors of this analytical model are analysed and modified coefficients are obtained from finite element method (FEM) simulation. A modified model of the EDSRS is developed according to the analytical model. Finally, the proposed model is verified by FEM simulations and experiments on a prototype, and a suspension and rotation experiment is conducted.

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Why is it important?

Summarising, the main contributions of this paper are: i. An accurate force and torque model for a novel EDSRS is developed for the first time. ii. The application range of the transfer-matrix theory is extended to the NBILIM, where new boundary conditions are developed in the modelling. iii. The errors caused by the assumptions in the transfer-matrix theory are analysed and the modified model is proposed.

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