Suppression of the Maglev Vehicle-Track Coupled Self-Excited Vibration Using Two Gap Sensors

Due to the flexibility of the steel track, self-excited vibration between the electromagnet and the track may occur when the EMS (electromagnetic suspension) urban maglev train is suspending above the track in a standstill. The self-excited vibration produces annoying high frequency noise, decreases the ride comfort of the maglev vehicle, and may cause fatigues to track structures. Therefore, in a commercial maglev line, the track induced high frequency self-excited vibration must be eliminated. In this paper, a new configuration of the gap sensors for the suspension system is proposed. In this configuration, two gap sensors are employed to measure the suspension gaps at different locations of the electromagnet, which is different from the conventional configuration of the urban maglev system in which only one gap sensor is used at the terminal of the electromagnet. Using two gap sensors, the deformations of the track can be measured at different locations, and by appropriate selection of the distance between these two sensors, the vibratory components of the track deformation included in the measured gap signals may be greatly cancelled by adding them together, leading to possible elimination of the self-excited vibration. The modeling of the multi-span maglev track and the principle of the proposed scheme are both investigated through theoretical analysis; a simulation is further undertaken to validate the effectiveness of this scheme. The configuration proposed in this paper is easy to realize in the urban maglev vehicle, and it is also benefit for decreasing the vibration of the suspension system in the presence of track irregularities when the train is traveling.