induced current in the guideway loop or sheet is opposite in direction
to the current in the superconducting magnet on the vehicle, producing
a magnetic levitation force. As the next vehicle magnet passes over
the loop or sheet, the direction of the induced current changes
in accordance with the change in magnet polarity. However, the magnetic
force remains in the upwards direction, and continues to levitate
The frequency of the alternating magnetic flux wave is determined
by the vehicle speed. At normal operating speed, the frequency is
high enough that the induced currents in the guideway loops do not
significantly decay due to their electrical resistance.
In the Null Flux suspension, the guideway loops are wound in a
configuration that reduces their induced current to a much smaller
value than is possible for the sheet or simple loop configuration.
Because the induced current is much less, the resistance losses
are very low, making the magnetic drag force on the vehicle very