Model of the Electromagnetic Levitation Device

1. Introduction From the principal point of view, the magnetic levitation is a method which is used for suspending an object in the air, without any physical contact. There are few main types of the magnetic levitation – electromagnetic, electrodynamic, transformation, superconductive and diamagnetic. All these are usually based on the force interaction between magnetic field and gravitation field. The magnetic levitation is especially used in some hi-tech devices (e.g. MagLev trains, frictionless bearings etc). The transformation levitation system is used for positioning of electrically conductive materials by electromagnetic forces. This type of levitation is usually utilized by metallurgists and material scientists and the most important practical application is a melting of metals. The electrodynamic levitation system (EDS) uses the moving of magnets to induce currents in an electrically conductive matrix. The induced currents produce a repulsive levitation force. This system is mostly used in the transportation. The diamagnetic levitation system is realized by situating a diamagnetic material close to a material producing magnetic field. The both materials will repulse each other. Disadvantage of the diamagnetic levitation is very low repulsive levitation force. The superconductive levitation system uses the superconductive materials and the source of the magnetic field – the permanent magnet. The external magnetic field is fixated in the superconductor and thereby the place stabilization of the superconductor and permanent magnet is held. At the present time, high temperature superconductors are mostly used. Our paper is focused on the electromagnetic levitation system (EMS). Its basic operating principles are described in the following text. A ferromagnetic object is suspended in the magnetic field of an electromagnet. It is obvious a feedback control circuit is necessary to ensure a stable position of the levitating object. A control unit adjusts the current in the elec-tromagnet. The position is tracked by a sensor; usually photo sensor, Hall Effect sensor etc. are used. According to the signal of the sensor the electromagnet is driven up or down. If the ferromagnetic object is above the desired position, the controller reduces the current in the electromagnet and the magnetic force as well. If the object is below the desired position, the current in the electromagnet increases. The most usual applications of the electromagnetic levitation are the transportation (MagLev trains) and magnetic bearings. Maglev train has always been considered to be the high speed passenger transportation between the major population centers. It is often viewed as a …