Analysis of the Low-Frequency Vibration of EMS Maglev Vehicles

The stability of suspension control of an EMS Maglev vehicle is an important aspect to be concerned when the vehicle is traveling. The PID controller is usually regarded as a simple and effective way in levitation control, but using PID controller, a kind of low-frequency vibration of the electro-magnet sometimes may occur during levitation. This kind of vibration greatly affects the dynamic performance of the levitation and decreases the ride comfort, which needs to be suppressed. To this point, a model of single electro-magnet levitation system using PD controller is established in this paper; and based on this model, several reasons of the vibration, including inappropriate parameters of the controller, improper use of filters, and time delay of signals from sensors, are discussed; at the end of this paper, several ways to reduce or eliminate the vibration are brought forward. Simulations and experiments carried out in a bogie prove the conclusions obtained in this paper.