The rotation of a permanent magnetic multipole wheel near a conducting non-magnetic plate creates a time-varying magnetic field that can produce by induction both repulsive levitation and propulsion forces. We constructed such an electrodynamic wheel using a motorized bicycle wheel with a radius of 12 inches and 36 one-inch cube Nd magnets attached to the rim of the wheel. The radial magnetic field on the outer rim of the wheel was maximized by arranging the magnets into a series of Halbach arrays which amplify the field along the rim. When a conductive metal “track” is immersed in this area of strong reversing magnetic flux, the time-dependent flux produces eddy currents, generating both lift (levitation) and drag (propulsion) forces on the wheel’s magnets, measured with force gauges. Measurements were taken at a variety of wheel speeds, and the results were compared to the existing theoretical predictions. The results depend on the resistivity and thickness of the conducting plate and on the clearance between plate and magnets. Partial levitation was achieved with the current electrodynamic wheel. Lift force per unit magnet volume was found. In the future, the wheel will be upgraded by doubling the number of magnets. Increasing the density of the magnetic poles will double the frequency at which the magnetic field oscillates, and so the thrust/lift force at a given angular velocity, because the magnetic flux will reverse itself through the track at a faster rate. Electrodynamic wheels may have applications in the magnetic levitation based transportation, since multiple electrodynamic wheels could be used on a vehicle to produce by the same mechanism levitation, propulsion and guidance forces over a conductive track. Our configuration of a plate suspended above the rotating wheel can serve also as a model of noncontact conveyance of conductive plates in electrodynamic conveyor belts.
Gaul, N. G., & Majewski, W. (2017). Low-Density Self-Driven Electromagnetic Wheel: Comparison of Different Tracks. Exigence, 1 (1). Retrieved from https://commons.vccs.edu/exigence/vol1/iss1/9