Research On Control Strategr Of Diesel Engine Air System Based On Mean Value Model

Exhaust gas recirculation(EGR)and variable geometry turbocharger(VGT)are main measures to reduce diesel emission from the inside of the engine However,with the enactment of the emission limit of the bare engine in the CHINA VI emission regulations,it is difficult to meet the emission requirements simply by controlling the EGR and VGT.Therefore,the intake throttle must be added,it can provide higher EGR rate and a certain air combustion ratio to meet the CHINA VI emission regulations.At present,there are few researches on the coupling control of the throttle,EGR and VGT,the existing strategy is controlling only by the calibration and simple PID control,it is necessary to design a nonlinear coordination controller for throttle,EGR and VGT.The research content of this paper is divided into four parts:1)We have built a four cylinder diesel engine model with throttle,EGR and VGT based on GT-POWER,then analyzing the effect of valve on emission and validating the model in steady and transient state.The results show that the GT-POWER model we built can accurately simulate the real engine and the emission of PM can be reduced after the intake throttle is added.2)The four-order mean value model of a four cylinder diesel engine is established based on the data provided by the GT-POWER model,and validating the model in steady and transient state.The results show that the mean value model has high precision.3)Based on the mean value model of building,this article designed the model predictive controller and the sliding mode controller,The control objective is to make the intake pressure and the intake air flow rate to track the target value.And then verified the robustness of the controller.The results show that the sliding mode controller has higher control precision and robustness.4)Based on the four-order mean value model of building,this article built a five-order mean value model of a two-stage supercharging diesel engine with EGR,VGT and throttle and designed a sliding mode controller.The results show that the sliding mode controller has good control effect.