Electrodynamic Suspension System (EDS)
The electrodynamic system, also known as the Linear express, was developed in Japan. The electrodynamic system is based on three basic principles, Lenz's law (motional emf), moving current creates a magnetic field, and that like poles of a magnetic field repel while opposite poles attract.
Superconducting wires are used in a basically solenoid shape to create the electromagnets on the train with a linear synchronous motor that provides the alternating current. These electromagnets can be placed on the train in a variety of designs, one with only two large electromagnets at the front and back of each car. Unlike a traditional train track, the "maglev" (magnetically levitating) train track is dug into the ground, covered with metal sheets, and has special coils on the sides to allow the train to move and levitate. Since the train does not initially levitate, there must be wheels to allow the train to reach a speed where levitation occurs.
The three forces allowing the train to move and hover over the track are propulsion, levitation, and guidance.
(For simplification, the assumption will be made that the outside environment does not affect these three systems.)
(pictures from http://www.rtri.or.jp/rtri/future_E.html)
Linear Express train, model MLX01-901 Track of Linear Express train in a tunnel