Study On Air-Fuel Ratio Control Strategy Based On State Observer

As China began to enter the ‘Vehicle Society’, environmental pollution, energyscarcity and traffic congestion problems get more and more attention. Because of theincreasing quantity of population and automobile every year, it is important to controlthe pollutants of vehicle exhaust emission, to a certain extent, can also reduce theformation of haze. In order to control exhaust pollution of the environment, countriesalso continue to introduce new standards and control regulations strictly, the mosteffective and direct way is to combine EFI fuel and Three-way Catalyst (TWC)conversion technologies, the key is to achieve precise control of critical air-fuel ratio.It has important practical significance to study gasoline engine Air-Fuel Ratio (AFR)control, and it is one of the current hot topic.Firstly, this paper analyzes the three major sub-model mean Hendricks enginemodel, due to fuel film formation of a special phenomenon, so in-depth analysis ofthe dynamic process of re-evaporation of fuel into the cylinder to form a film and twoimportant parameters X and f, it is the key to feed-forward compensation control.Through analyzing the transmission characteristics of mixture AFR in the cylinder toobtain the transfer function of AFR between the in-cylinder and measured by UEGO,and then establish air-ARMA model to identification parameters and by themethod of least squares, and through en-DYNA real-time simulation platform toverify the correctness and reliability of the identification method.Because of sensor lags when some unexpected situations, so establishingobservation using the extended Kalman filter based on the intake manifold pressurestate to estimate the intake manifold air, and through en-DYNA real-time simulationplatform to verify the correctness and reliability.Finally, this paper designed fuel film feed-forward controller and PIDfeed-back controller, and addition fuel film dynamic model of the en-DYNAsimulation platform to control open-loop and closed-loop control of an engine controlstate simulation analysis: the results of the PID controller is ideal linear controlsystem, after the feed-forward PID controller and the amount of fuel feed-back control instruction quantity of fuel into the cylinders of the engine ECU emittedalmost equal to the theoretical air-fuel ratio is maintained at the value almost always.Perturbation is applied simultaneously to more fit the actual engine operatingenvironment for dynamic model of the engine fuel film applied white noise,re-simulation, and analyzing the results of a new group concluded: In the case ofnoise imposed after control, participating in the burning fuel into the cylinder massflow and fuel mass flow is basically the same command, you can also control theair-fuel ratio between0.95-1.05, visible control strategy of this study under theinfluence of the disturbance and noise, the effect of the air-fuel ratio control good.