Effect of levitation gap feedback time delay on the EMS maglev vehicle system dynamic response

Abstract

EMS maglev train uses the active control system to maintain the levitation stability, time delay is widespread in control system. However, the existing maglev dynamics studies rarely consider the effect of time delay, so these analysis results cannot directly guide the engineering design. This paper starts from a theoretical analysis of the levitation stability of a single electromagnet levitation system to obtain the theoretical critical value for the time delay. Then the model is gradually extended to a complete vehicle model and a vehicle-girder coupling dynamics model to find the time delay engineering critical values for the complex coupling system. In order to seek ways to reduce the influence of time delay on the dynamic responses, this paper analyzes the influence regularities of the running speed and control parameters on the dynamic response under the effect of time delay. The result shows that the theoretical critical value of the time delay is equal to the ratio of the differential coefficient and proportional coefficient of the PID controller. For a complex maglev system, the engineering critical value is less than the theoretical critical value. Higher running speeds lead to time delay having a more obvious effect on the maglev system’s dynamic responses. Selecting the smaller proportional coefficient and appropriate differential coefficient for the levitation control system can expand the stability region and reduce the influence of time delay on the maglev system. This analysis is helpful and meaningful to the understanding of the EMS vehicle system stability, and helpful to explore the reason of violent coupled vibration in actual engineering.

A Review of Levitation Control Methods for Low- and Medium-Speed Maglev Systems

“…The time delay in the signal transmission can be introduced by adding a time-delay state function to the entire dynamic model [125]. The impact of time delay on the dynamic response under the influence of a PID controller has been analyzed, including an examination of the relationships between running speed, control parameters, and response regularities [126]. To deal with the factors illustrated above, observers, such as disturbance observers [52] and flux density observers [124], combined with adaptive algorithms are usually adopted.…”

PID Control of Magnetic Levitation (Maglev) System

“…This research discusses a magnetic levitation system, which will require many experiments. Maglev control will be decisive in conducting research related to this system [9][10]. In this system, a position control system of an elevated object will be designed at a certain height under an electromagnetic field generated from a voltage-fed coil [11].…”