Inductrack (or Inductrak) was invented by a team of scientists at Lawrence Livermore National Laboratory in California, headed by physicist Richard F. Post, for use in maglev trains, based on technology used to levitate flywheels.
[1][2][3] At constant velocity, power is required only to push the train forward against air and electromagnetic drag.
Above a minimum speed, as the velocity of the train increases, the levitation gap, lift force and power used are largely constant.
As a Halbach magnet array passes over the loops of wire, the sinusoidal variations in the field induce a voltage in the track coils.
This occurs because the inductive impedance increases proportionately with speed which compensates for the faster rate of change of the field seen by the coils, thus giving a constant current flow and power consumption for the levitation.
The Inductrack II has more capabilities of levitation at relatively low speed for use in individual (PRT) or urban transport and uses a cantilevered track.
Tests have shown that low-frequency oscillations (1 Hz) occur and a US patent for mechanically damping the track itself (on Inductrack II) was issued (7478598).