Research Of The Self-adapeted Control Based On Model For Diesel Engine With Turbocharging System

The research on regulation law and control strategy of turbine bypass valve is of great significance for improving the adaptability of diesel engine to altitude.In this paper,based on the optimization algorithm of the previous dual-nozzle turbine flow characteristics model,a model of the waste gate turbocharging system and the regulated two-stage turbocharging system has been deduced respectively.The singular perturbation method is applied to simplify the model.The relationship among the opening of bypass valve,compression ratio and expansion ratio is obtained.Based on the derived model,the experimental data of diesel engine is applied to analyze the trajectory of turbocharging system.The equilibrium and stability of the turbocharger system are researched.The moving tendency of the equilibrium state under different conditions is investigated to determine the influencing factors of the system trajectory.Different control models are proposed for the two kinds of turbocharging systems respectively.For the waste gate turbocharging system,a feedforward control strategy based on model combined with the target compression ratio PI feedback control has been presented,motion planning and anti-windup function has also been designed.For the regulated two-stage turbocharging system,the control model applies feedforward control based on model and proportional feedback regulation method to avoid the excess of the high-pressure stage compression ratio and the overspeed of the high-pressure stage turbine.The use of Poincaré-Bendixon theorem shows that after the system is controlled,it can converge to the only stable equilibrium state,indicating that the control strategy is reasonable.Based on the OpenECU control system development platform,a control model of high-pressure stage turbine bypass valve for regulated two-stage turbocharging system is built,and the experiment at different altitudes is carried out.The control strategy based on model can directly calculate the feedforward of bypass valve and reduce the calibration effort.The maximum error between the actual turbocharging pressure and the target turbocharging pressure did not exceed 1.3%.The control system showed quick transient response,the settling time under acceleration condition and upload condition does not exceed 10 s,and 15 s respectively.