Research On Suspension Control Of Low-speed Maglev Train Running On Step Railway

Due to machining error, installation error and roadbed sedimentation, rail-joints are prone to become railway step. Experiments show that if the suspension system does not adopt effective control methods, the train will vibrate severely and even become unstable when running across railway step in different speeds. Therefore, it is important to simulate the actual suspension control process when the train runs across railway step with different heights at different speeds. Correspondingly the suspension control algorithm for restraining the disturbance from railway step to improve the running quality of low-speed maglev train. Here, the main work of the paper can be organized as below.Firstly, by adopting state feedback control method, a two-point suspension model for electro magnetic module of low-speed maglev train is built. Then a two-point suspension control algorithm is designed, and the suspension characteristic of maglev train running on smooth railway is simulated and analyzed. Simulation results show that the two-point model can validate the dynamical behavior of suspension control system effectively.Secondly, when the train runs across railway step, according to suspension gap measured by sensors and the real-time geometry relation between magnet and railway, equivalent clearance which can reflect the real air-gap of magnet is calculated. The analysis and simulation results show that when the train runs across the railway with the same height and length of sustain orbit, the vibration is most obvious at the speed of 50km/h. At a fixed speed, the higher the rail step is, the much violent the vibration will be. These results accord with the real facts of the experiments entiretly.Thirdly, comparing the two vibration facts from external disturbance and running across railway step, it can be found that the trend of clearance and vertical velocity signals measured by sensors are very different. Three rules are proposed to identify what time railway step occurs and what the height of step is. With the information obtained by the rules, a control algorithm of scheduled clearance compensation is presented by compensating the scheduled clearance of suspension system real-time and changing the suspension equilibrium quickly. Furthermore, in order to reduce the impact of changing the scheduled clearance on suspension system, a reasonable transient process is arranged for changing the scheduled clearance with arranging transient process theory. Simulation results show that, by adopting the control algorithm, the fluctuation of suspension clearance and acceleration is reduced to 1/3 and 1/10 respectively. Thus, the capacity of control system for restraining the disturbance of railway step is improved evidently.In a word, the simulation results in the paper are consistent with the test phenomena when the train running across railway step, and the proposed control algorithm can also restrain the disturbance from railway step effectively. The new control algorithm should be validated on test line for a long time in the future.