Influence Of Levitation Control Algorithm And Feedback Gains On Coupled Vibration Between Medium-low Speed Maglev Vehicles And Steel Switch Girder

To support and guide the medium-low speed EMS maglev train,noncontact electromagnetic attraction force is proposed,while the active feedback control is used to maintain a levitation gap of about 8 mm between the maglev train and the track.To reduce the occupied area of land,maglev transportation is widely adopted elevated guideway.Therefore,the maglev vehicle-track-bridge dynamic interaction becomes a key concern for maglev transportation technology development.In fact,the strong coupling vibration between maglev train and switch girder appears in the medium-low speed maglev transportation engineering applications around the world.At present engineering practice,to reduce the negative effects mentioned above,the methods of increasing the rigidity of beam and adding TMD damper are adopted.However,these measures increase the construction cost of maglev tracks.To explore the low-cost and efficient method to suppress coupled vibration of maglev vehicle-switch girder system,this paper uses simulation analysis on coupled vibration between maglev vehicle and the steel switch girder under different levitation control algorithms and feedback gains.According to the extensive parameter research,the coupled vibration mechanism of the maglev vehicle-switch girder system is analyzed,some recommendations on levitation control algorithm and feedback gains are proposed.Firstly,this article uses the modeling and analysis of the electromagnetic levitation control system,and designs the position loop and current loop subsystems based on the hierarchical control idea.As for the position loop,this article considers the ProportionalIntegral-Derivative(PID)control algorithm,the feedback control algorithm based on the state observer and the PID control algorithm based on the notch filter respectively.While using the PID levitation control algorithm studied the influence of levitation control parameters on the frequency characteristics of single electromagnet levitation system as an example.Furthermore,this paper regards the Changsha maglev train and the 25m-span concrete track beam as the object,the coupled dynamic response analysis of the maglev train and the track using the PID control algorithm proposed.By comparing with the actual measurement results in the existing literatures the reliability of the dynamic modeling and simulation calculation method is verified.Secondly,this paper establishes the coupling dynamics model of the middle and low speed maglev vehicle-steel switch girder,and the maglev transportation system distributed collaborative simulation platform developed by the research group is used to calculate the coupling vibration response of maglev vehicle-switch girder under the PID control algorithm and the feedback control algorithm based on the state observer.Then this paper compares the response difference of the maglev vehicle-switch girder under these two levitation control algorithms.When the maglev train passes through the switch girder at low speed,the coupling between the maglev vehicle and the switch girder will vibrate strongly.To solve this problem,the simulation calculating the coupled vibration response of the maglev train and the switch girder using the PID control algorithm based on the notch filter.Then,the mechanism and effect of the notch filter to suppress the coupled vibration of the maglev vehicle-switch girder are analyzed.Finally,according to the PID levitation control algorithm used in the actual project,this paper takes the driving speed of 30 km/h and 100 km/h as examples,the coupled vibration response of the maglev vehicle-switch girder under the conditions of different gap feedback coefficients and speed feedback coefficients is analyzed,and the variation rule of the coupled vibration response of the maglev vehicle-switch girder with the gap feedback coefficient and the speed feedback coefficient is proposed.The research results demonstrate that to avoid excessive coupling vibration of the maglev vehicle-switch girder,the optimal range of the levitation controller’s gap feedback coefficient is 7000～9000,and the optimal range of speed feedback coefficient is 45～60.Combining with engineering practice,the recommended order of debugging the levitation control system parameters is as follow.Firstly,adjust the gap feedback coefficient according to the amplitude of the gap fluctuation.Then,adjust the speed feedback coefficient to reduce the coupled vibration acceleration response of the maglev vehicle-switch girder.