Research On Control Of Semi-Active Suspension Of High Speed Railway Vehicles

Semi-active suspension system is consist of the traditional springs and controllable dampers,which has lower cost compared to the actuator in active suspension system,with suitable damping control strategy. It can attain to the performances which is nearly to active suspension system,with little consume of energy,this is the reason that the semi-active suspension system has attraction. But the application of semi-active suspension system is determined by two factors,one is the proper strategy of damping control,another is the practical controllable damper. This is the important content of this paper.The damping control rules have two forms,one is the on/off damping control,another is continuous damping control. The skyhook damper,which is more effective in active suspension system,is firstly researched in the paper. The on/off control performances of the skyhook damper in semi-active suspension system,the occur of chatter and its avoiding are analysis. The continuous damping rules are derived according to the feature of damping curve given by the controller in active control system.The continuous damping control rule using adaptive controller based on artificial neuro network(ANN) is researched. This rule has no strict demand for the bandwidth of the damper,the cost of damper is low,the practicality is good.This continuous rule can put the suspension system in the optimal damping state. The skyhook principle can be combined in this control rule,which can further attenuate the vibration of the car-body in lower frequency range,but the acceleration response in higher frequency range tend to be larger.It is also analyzed that the time delay of the control system has different influences on both active and semi-active suspension systems. Analysis and the simulation show that the time delay in semi-active system can not influence the stability of the system,but has influences on the response performances of the system. Too large system time delay will enlarge the acceleration response,the ride corfortabilty will be lower,but it can not make the system unsteady. The results of simulation has proved this conclusion.For the research of the damping control strategy one type of controllabledamper,magnetico-rheological(MR) damper,was constructed and tested,the damping force and displacement characteristic curves,the damping force and velocity characteristic curves are obtained,so that the damping force and voltage(current) model,or the damping coefficient and voltage(current) model can be further obtained. Damping force can be controlled in one of the two ways,open loop control or force feedback control.During research,in this paper,both damping control strategy and the damper modeling are combined in the same system model,and the simulation model. During the simulation of the secondary lateral suspensions for the high speed passenger vehicle with no-bolster bogie,the effective using semi-active control to improve the ride comfort are studied. The results of simulation show that,compared to the passive suspension system with optimal damping,using continuous damping control rules,the RMS values of lateral response acceleration car body can be reduced 20% to 25%,maximum values( 3er ) of lateral acceleration can be reduced 40% to 50%,the ride comfort index can be reduced 10% to 15%.The research in this paper has proved that,it is effective using semi-active damping control to improve the ride comfort for the high speed passenger vehicle . It is feasible using adaptive controller to output the continuous damping. Because of the speciality of the controlling force of semi-active suspension system,the system time delay has no influences on the system stability. The MR-damper is good on the principle,on control effect,on response characteristics,etc.,after further improvements it can be used as a selectable controllable damper for semi-active suspension system.