Study On Robust Control For Suspension System In Midium Speed Maglev Train

In order to adapt to the new urbanization and regional economic integration,provide a convenient way of rail transit between satellite cities and filling the space of the maglev transportation speed spectrum,the medium-speed maglev train with 200km/h adopts permanent magnet-electromagnetic hybrid suspension(PEMS)is raised in the recent years.Compared with the traditional electromagnetic suspension system,the PEMS can reduce the power consumption of suspension and reduce the heating of electromagnet.However,with the increase in speed and the introduction of permanent magnets,not only bring a significant increase in external disturbance,but also bring the control difficulty and so on.In this paper,a hybrid suspension system of medium speed is developed.And the flux density is taken as the control output.The robust control of hybrid suspension system is studied.Firstly,the uncertainty model of PEMS system is established.By using the suspension module as the control object and the flux density as the control quantity,the model of the system structure uncertainty based on the module mass,moment of inertia and force-magnetic flux density coefficient is established.The factors neglected in the modeling process are unified as the external force disturbance for the next modeling.The range of uncertainty is discussed with the consideration of the actual working environment.Secondly,the disturbance boundary of the suspension system is determined.According to the characteristics of different force disturbances,the corresponding treatment scheme is proposed.The loss of the levitation force due to track eddy currents and electromagnet misalignment does not exceed 10% and is taken into account as part of the uncertainty modeling of flux density.For the force disturbance caused by vehicle load change,the force mainly affects the force-flux density coefficient of the model,and its load range is equivalent to the model parameter uncertainty range.The cross-wind lift force and the coupling force between the modules are transferred from the air spring to the module,so,the boundary range of such interference forces is determined from the deformation and equivalent model of the air spring when the train is running.For the force disturbance caused by the anti-roll beam,the elastic boom connected with the elastic suspension is equivalent to the spring model,and the range of the force disturbance is determined according to the suspension gap.Thirdly,the flux density observer is designed.The magnetic flux density has the natural advantage as the control quantity of the hybrid suspension compared with the current control.In this paper,the deficiencies of two existing flux density observers are pointed out,and an integrated magnetic flux density observer based on on-line resistance identification is designed.Experimental results show that the observer can meet the control requirements of hybrid suspension system.Fourthly,the saturation requirements of the controller and the output performance of the system are also discussed.From the aspects of magnetic material and the controller hardware limitation,the parameter range of the flux density variation and flux density change rate of the two controller output limit is determined.In order to minimize the fluctuation of the average gap of the floating point when the track is staggered,the bandwidth requirement of the suspension system is determined.Finally,a robust controller for PEMS system is designed based on the μ method.Based on the above research,the robust controller is designed.After Hankel reduction of the model,the controller is realized digitally in the suspension controller based on digital signal processor(DSP).The experiments are carried on medium-speed hybrid suspension bogies.By discussing the range of uncertainty and designing the robust controller,the system has raised the ability of resisting environment disturbance and tracking the guideway.