Impact of the Magnet Span on the Forces of Electrodynamic Suspensions with an Alternate Permanent Magnet Arrangement

Permanent magnet (PM) electrodynamic suspensions offer a simple and robust solution to assure the magnetic levitation of high-speed transportation systems. Halbach arrays (HAs), which are the PM magnetic field sources with the best performance, are more complex to implement than alternate poles configurations. Therefore, starting from a topology optimization, this paper studies the impact of geometrical parameters, and mainly the magnet span, on the alternate PM structure with the aim of improving its performance. It is shown that the lift-to-weight ratio can increase by 11% when changing the span of the permanent magnets for specific magnet dimensions, closing the difference with the Halbach array to only 2%. When considering the edge effects in 3-D, the alternate PM configuration even outperforms the HA. However, even though the span has also a positive impact on the lift-to-drag ratio, this last metric is not in the favour of the alternate PM arrangement.