Development of a simple MAGLEV system for a low-speed wind tunnel

The present work seeks to develop a magnetic levitation (MAGLEV) system suitable for a low-speed wind tunnel, to support light-weight models through building-block design, development and experimentation. Design of an appropriate electrical circuit, design of components, results obtained by simulation (on ORCAD-PSPICE) and experimental results obtained through bench-tests are presented. A set of button-type permanent magnet (total weight = 4 gm.) was considered as the object to be levitated and a coil-wound electromagnet used to create a magnetic force which opposed the weight of the object. Distance between the object and the electromagnet was measured using locally available Hall effect sensors and the output amplified using a locally available differential amplifier. Pulse Width Modulation was used to control the current required to generate the required electromagnetic force. The results show that even though the electromagnet was capable of levitating the object, maintaining perfect alignment of the CG of the object with respect to the centre of the electromagnetic force is an important issue. It is therefore suggested that a bar-magnet for the object and a horseshoe magnet for generating the required electromagnetic force would provide a solution. Further, since the model of a prototype can experience aerodynamic forces and moments along three axes, a satisfactory MAGLEV system requires use of multiple horseshoe magnets which can provide vectored electromagnetic forces to keep the object in force as well as moment equilibrium.