Semi-active Control Of High-speed EMUs And Time Delay Analysis Based On Magnetorheological Damper

At present, high-speed Electric Multiple Units (EMUs) technology is one of the most quickly developed leading techniques. The great success of high-speed EMUs is achieved in China, and high-speed EMUs have put the new vigor into railway transportation industry. With increasing of running speed of EMUs, a lot of important research subjects have been proposed.On the one hand, due to the characteristics of high-speed EMUs, high speed, decentralized motors and groupage system, traditional study methods of locomotives and vehicles are no longer effective for high-speed EMUs. Numerical simulations and experimental results show that the vehicles in a same train have different dynamic performances due to intercoupling effect. Thus, it is necessary to build a whole train model for studying the dynamic performance of the high-speed EMUs.On the other hand, since the intercoupling effect of vehicles and that of wheel/rail increase sharply with the increase of the speed, ride index and safety of high-speed EMUs become worse gradually. In order to reduce vibrations of car body and improve system performance, semi-active control is adopted in the view of improving performance and saving consumed energy. The performance of semi-active control is close to active control, but its consumed energy is significantly less. In many kinds of dampers, Magnetorheological (MR) damper is one of the best actuators for its large damping force, wide workspace, responding quickly and so on.This work deals with building high-speed EMUs model, identifying parameters of MR damper model, designing of semi-active control strategies, analyzing the effect of time delay on semi-active control performance and so on. The main work and innovative contributions of this dissertation are as follows:(1) On the basis of mechanical characteristic experiment of MR damper, the parameters of MR damper models are identified. A new method, Independently Parameter Adjust Method (IPAM), is proposed to make the choice of damping force adjustment parameters well-founded. The error due to traditional identification method, which relies on experience and try-error method, is reduced greatly, and the effect of coupling among parameters is avoided by using IPAM. And the parameters of Bouc-Wen model and Bouc-Wen modified model are identified successfully.(2) A 300 km/h high-speed EMUs model with six motor and two trailer vehicles is built using a multi-body dynamic software ADAMS/Rail in this study. In order to approach actual case, the EMUs model includes a lot of elements, which involve 224 movable parts and 466 degrees of freedom. And the nonlinear effects of many elements are also considered.(3) Numerical simulations of high-speed EMUs model with single vehicle and that with a train model are performed, whose dynamic performances, such as stability, ride comfort, safety and curve passing, are evaluated under various conditions such as running speed, railway line conditions and track spectrum. Then, the influence of the number of vehicles in the train model on the dynamic performance of the system is investigated.(4) Inspired by Sky-Hook (SH) damping control and Acceleration Driven Damping (ADD) control, a modified semi-active control strategy, SH-ADD control, is proposed and applicable to high-speed EMUs. The semi-active control system consisting of semi-active controller, inverse model, forward model of MR damper and low-pass-filter is established in order to investigate the effect of several control strategies on the dynamic performances of high-speed EMUs. Using ADAMS-Matlab co-simulation, semi-active control performances such as lateral ride index, derailment quotient, unloading rate and wheel/rail forces are evaluated. The simulation shows that the performance of SH-ADD control is better than SH control and ADD control in ride comfort and safety.(5) Time delay in semi-active control system is divided into two kinds of cases, acquisition time delay and actuation time delay, according to the mechanism of time delay occurrence. A new method is proposed to analyze the two kinds of time delays. By using this method, the effective region of semi-active control is obtained according to the effects of two kinds of time delays on the semi-active control performance. When the time delays are within this effective region, the performance of semi-active control works well. Otherwise, the semi-active control fails. The results show that the effective region of semi-active control is shrank with the increase of running speed of high-speed EMUs. The performance of SH-ADD control is better than other controls when considering the effects of time delays. Thus, it is a great benefit to use MR damper with less time delay and better semi-active control strategy in high-speed EMUs.