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Analysis and Research on Automotive Engine Air-Fuel Ratio Control Strategy

Author: QuLing
Tutor: PeiRun
School: Harbin Institute of Technology
Course: Control Science and Engineering
Keywords: Engine air-fuel ratio Mean model PID controller Sliding mode controller
CLC: U464.17
Type: Master's thesis
Year: 2009
Downloads: 239
Quote: 3
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Abstract

The engine air-fuel ratio control is an important part of the automotive electronic control systems, thus gaining wide attention from scholars at home and abroad, because of its power, fuel economy and exhaust emissions performance of the car has a huge impact. The content of this study is the automotive engine air-fuel ratio control to the desired air-fuel ratio in the machine outside purification device catalytic converters to achieve the best efficiency (14.7), so that the fuel injection system of the engine to the most reasonable amount of fuel injection, to the engine system to achieve the best state power, fuel economy and exhaust emissions. The control system according to the operating state of the engine in real time, as a feedback signal to the output of the air-fuel ratio of the system to calculate the optimum amount of fuel injection. Conduct air-fuel ratio control we must first understand the physical model of the engine air-fuel ratio, engine air-fuel ratio system modeling become a very important part of the controller design. The research on the analysis of dynamic characteristics of the engine control object, and the subsequent development of the air-fuel ratio control system and controller design has important significance. This article describes the structure of the engine system, to the engine air-fuel ratio of the model-based control design ideas, by analysis of the data on the physical model of the engine and the pulse spectrum, the establishment of a nonlinear model of the engine air-fuel ratio, and in the model on the basis of fully consider the uncertainties of the model parameters, analysis of model characteristics, simplified control model, en-DYNA simulation platform to verify the accuracy of the model. Non-linear air-fuel ratio of the model of linear time-domain system of linear model, based on the air-fuel ratio and apply the Matlab Simulink optimization module (SRO), the design of the engine air-fuel ratio of the PID controller. Concentration of the mixture for the actual engine air-fuel ratio can not be measured directly, this paper presents a sliding mode observer to make estimates. Finally, the PID controller is applied to real-time simulation system of the engine to verify that the control effect of en-DYNA. Subsequently, the engine air-fuel ratio of the sliding mode controller is designed based on the nonlinear model of the engine air-fuel ratio. And apply it to real-time simulation system of the engine. Under steady state operating conditions of the engine and two cases of transient operating conditions, the control effect of the sliding mode controller with PID controller to compare. Simulation results, the conventional PID controller is designed to be simple, but the system disturbance rejection capability is weak, robustness. This article sliding mode controller is designed based on the nonlinear model the impact of interference in the system is not sensitive to the sliding system into the sliding mode, the motion of the system will not be further affected, with a strong robustness.

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