There are two well known basic concepts for achieving magnetic levitation of vehicles: one is based on electromagnetic attraction (EMA); and the second method is based on electrodynamic repulsion (EDR). In turn, each of these concepts has at least two variations (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19)1
This paper presents a third form of levitation known in the Ukraine as the Magnetic Potential Well (MPW) developed by Kozoriz (20, 21, 22 and 23), and in the West as Laithwaite's Magnetic River (24)(25). The MPW concept, in effect, electrifies the passive sidewall levitation coils of the RTRI EDR (16) system to obtain levitation at zero vehicle velocity and during acceleration to cruising speed. This dc electrification of sidewall levitation coils eliminates the need for wheels during acceleration from standstill and deceleration in the station.
Specifically, MPW levitation force exhibits a stable positive slope as the levitation gap increases. However, it then passes through a maximum attraction force and changes to an unstable negative slope, as levitation gap increases further. One circuit must be superconductive (SC), and the second circuit can be dc electromagnetic or permanent magnetic. The guideway dc circuit can be: a two-wire dc line pair of infinite length, or discreet coils in a null flux circuit.