This paper deals with levitation control for a doublesided bearingless linear-motor system. Analytical design rules for a state-feedback gain and a state observer are derived. To decouple the production of forces in thrust-and normal-force directions, feedback-linearizing control based on the magnetic model is proposed. The proposed control design is tested in an experimental system consisting of four individually supplied linear-motor units in a double-sided configuration. The results from time-domain simulations and experimental tests suggest that the proposed control design can successfully provide smooth transition to contactless operation and retain the stable levitation during the movement in the thrust-force direction.

Abstract-This paper deals with a model-based state-space flux-linkage control of a dual three-phase-winding bearingless synchronous reluctance motor. Analytical tuning rules for the state feedback, integral action, and reference feedforward gains are derived in the continuous-time domain. The proposed method is easy to apply: the desired closed-loop bandwidth together with the estimated magnetic-model of the motor are required. Furthermore, the proposed method automatically takes into account the mutual coupling between the two windings. A simple digital implementation is provided and the robustness of the proposed control method against the system parameter inaccuracies and eccentric rotor positions is analyzed. The proposed controller design is evaluated by means of simulations by keeping in mind the most important aspects related to an experimental evaluation.

This paper deals with dynamic modeling of a bearingless flux-switching permanent-magnet (FSPM) linear machine. Based on equivalent magnetic models, an analytical model is derived, taking into account airgap variation and magnetic saturation. The effects of these phenomena are analyzed using finite-element method (FEM) simulations of a test motor. The proposed model can be fitted to the FEM data or measured data. The model can be applied in real-time control of a magnetically levitating motor drive as well as in time-domain simulations. Experimental results are used to validate the proposed model.

This paper deals with dynamic models for threephase bearingless flux-switching permanent-magnet (FSPM) linear machines. This machine type can be used to build a magnetically levitating long-range linear drive system, whose rail does not need any active materials apart from iron. A dynamic machine model is developed by means of equivalent magnetic models, taking into account air-gap variation and magnetic saturation. The effects of these phenomena are analyzed using finite-element method (FEM) simulations of a test machine. The parameters of the proposed model can be identified using the FEM or measured data. The model can be applied to real-time control and time-domain simulations. The model is validated by means of experiments.

This paper presents a novel analytical method for electro-mechanical design of a high speed long-term flywheel energy storage system and thermal evaluation of possible operating modes of the system. Flywheel's composite shell rotor along with the motor/generator unit are assumed to be placed into a sealed vacuum chamber, which presents a challenge of heat transfer, produced by rotor losses. Developed method takes into account thermal radiation properties of the rotor and is realised using Mathcad software, which allows for quick investigation of any flywheel configuration. The method involves calculations for preliminary rotor sizing and determining achievable operation modes, while keeping the rotor under a specified temperature limit. Results of using this method for studying dependencies of thermal performance on initial system parameters are presented and conclusions are drawn. Based on the conducted study, recommendations on system design considerations are given.