Study On Control Method Of Electronic Throttle In Gasoline Engine

Environment and energy issues have been widely concerned around the world. The increasingly stringent emission standards and fuel consumption standards formulated by each country put forward higher requirements for power, economy and emission performance of automotive engine. As one of the important components of the electronic fuel injection system, electronic throttle controls air intake precisely according to vehicle torque requirements, which has important influence on the performance of the engine. In terms of electronic throttle, the key is the control technology which has high requirements for real-time, stability and reliability. The relevant technology are not yet mastered by China. A large number of experimental calibration is used in foreign countries, while this method has problems of high cost and long development cycle. Therefore, it has important practical significance to study the control technology of the electronic throttle.Operating principle and system characteristics of electronic throttle are analyzed in this thesis. The mathematical model and simulation model of electronic throttle control system are established through dynamic analysis. To evaluate the air quality, an improved method for evaluating the ordered uniformity of the air flow is adopted. And then, the indexes of the ordered uniformity of the air flow and the flow coefficient are used to evaluate the air flow characteristics. To determine the target opening angle, the air flow characteristics are analyzed under two conditions, which are the original state of the inlet and the improved state of the inlet(in the case of the installation of flow vane).The correction method of target opening angle for throttle is studied on the improved state of the inlet, which establishes the foundation for the determination of target opening angle on the improved state of the inlet. In terms of the control method of throttle control, the characteristics of PID control, fuzzy control and other control methods are analyzed, a staged composite control method is used. The control process is divided into different stages according to error between actual opening angle and the target opening of the throttle in the control process. If the deviation exceeds a certain threshold value, the method of seeking table is used, else classic PID control method is used.The control effect of staged composite control strategy is simulated and verified through software modeling. Based on that, the hardware experiment platform is set up with the DSPIC30F4012 microcontroller as main control chip, and corresponding software system is designed. Using the German imported electronic throttle Bosch(model of 0280750232) as experimental control object, the experimental verification of staged composite control method is carried out.Simulation and experimental results show that the staged composite control method used in this thesis can effectively alleviate the contradiction between overshoot and rise time. This method is simple, reliable and has good real-time performance. It can achieve the desired control effect.