ABSTRACT
Repulsive forces (RFLS) occur between two current carrying conductors of positive and negative polarity or between a moving current carrying coil and a short-circuited fix electric circuit (conducting sheet or shorted coil) and also between a moving permanent magnet (PM) and a fix short-circuited electric circuit or between two PMs of opposite polarity. The repulsive (electrodynamic) force, in contrast to attraction force (Chapter 20), is such that it repels the other side and thus tends to be statically stable. Not so dynamically, but the damping of the motion oscillations is simpler than for ALSs. Also, the distance (gap) between the mover and the guideway can be 10 times larger than in ALSs for the same speed (for MAGLEVs, U max > 100 m/s). But to obtain high levitation force RFLS per weight for a net mechanical airgap of around 100 mm, superconducting dc electromagnets on board of vehicle are required. A row of such superconducting magnets of opposite polarity on board of MAGLEVs interacts through motion-induced currents within an aluminum sheet or ladder secondary to levitate the vehicle. Strong PMs may be used instead (at room temperature), once their remanence flux density would go hopefully, in the near future, above 2 T or so. The interaction of levitation, guidance, and propulsion in RFLS–MAGLEVs has been introduced to save energy and reduce initial system cost.
