Railway switch mechanism

Abstract

A linear induction rail switch mechanism having at least one linear induction motor (LIM) for transversely thrusting a switch track from a first position to a second position. To reduce the frictional forces during transverse movement, the switch mechanism can be levitated from the underlying structures. The switch can have at least one controllable power supply which may supply electric power to an individual LIM or groups of LIMs, which may be three-phase motors. The switch may include a vital controller which is connected to at least one controllable power supply. The vital controller responds to at least one of a feedback signal from a controllable power supply, a feedback signal from a LIM, a feedback signal from a switch track, and a remote signal. The LIM may include a primary inductor which is affixed substantially rigidly to the ground and a secondary which is affixed to the switch track. In some embodiments, the secondary may be a ladder secondary. When the LIM is energized, the ladder secondary becomes magnetically attractable to the primary inductor, and thus the ladder secondary becomes movable responsive to the magnetic field generated by the primary inductor. The controllable power supply used with the switch can include a solid state power converter having a controlled output voltage, which may employ a pulse-width-modulation scheme. The solid state power converter may be a variable-voltage, variable-frequency converter, although a variable-voltage fixed-frequency converter also may be employed.