基于dSPACE的单燃料CNG发动机电控单元设计

发布时间：2018-03-29 05:02

本文选题：空燃比　切入点：点火提前角　出处：《合肥工业大学》2015年硕士论文

【摘要】：作为一种新型的清洁能源,天然气已经在各个行业被广泛使用,尤其是汽车行业。天然气发动机类型主要有两种,即单燃料天然气发动机和两用燃料天然气发动机。随着现代控制技术的发展,发动机的空燃比和排放等控制需求也越来越严格,因此,开发具有市场竞争力的CNG发动机电子控制单元成为了当前的一大热点。’ 面对越来越复杂的电控单元系统,传统的ECU开发方式存在着周期长,成本高,压力大的缺点,尤其对于高度复杂的、非线性的发动机控制单元设计而言,不论是软件开发还是测试都变得愈加困难。本文使用MATLAB/Simulink软件与dSPACE系统的RTI模块相结合,建立单燃料CNG发动机快速控制原型,以模块框图化的形式实现了CNG发动机的控制算法设计。主要设计了：针对天然气发动机空燃比控制的,基于宽域氧传感器的闭环和自学习控制策略；基于转速反馈的点火提前角自动标定系统；CNG发动机恒转控制算法；针对不同负荷下转速与节气门的关系进行了传递函数的辨识,并且进行了反馈PID仿真控制研究。在对博世LSU4.2宽域氧传感器工作原理分析的基础上,设计的基于宽域氧反馈的空燃比PID闭环和自学习控制策略,实现对空燃比的有效控制,并且帮助喷气MAP的标定,标定者不需要对每一个工况点进行非常精确的标定,在发动机工作时依靠闭环和自学习就可以将喷气脉宽调整到合适的值,节省喷气MAP标定时间,同时也可以弥补发动机磨损老化造成的空燃比偏移；基于转速反馈的点火提前角标定系统可以帮助点火MAP的标定；发动机恒转控制系统是为扩大控制系统的适用性,采用PID控制策略通过实时调整节气门开度使转速始终稳定在设定目标值附近；基于模型的节气门和转速反馈PID控制仿真研究是预先辨识出不同负荷下的转速与节气门的传递函数,然后建立反馈PID控制模型,这样就可以方便的进行PID参数的整定。
[Abstract]:As a new type of clean energy, natural gas has been widely used in various industries, especially in automobile industry. There are two main types of natural gas engines. With the development of modern control technology, the control requirements such as air-fuel ratio and emissions are becoming more and more stringent. Developing Electronic Control Unit of CNG engine with Market Competitiveness has become a Hot spot at present. In the face of more and more complex electronic control unit (ECU) system, the traditional ECU development method has the disadvantages of long period, high cost and high pressure, especially for the highly complex, nonlinear engine control unit design. Both software development and testing are becoming increasingly difficult. In this paper, the rapid control prototype of single-fuel CNG engine is established by combining MATLAB/Simulink software with RTI module of dSPACE system, and the control algorithm of CNG engine is realized in the form of block diagram. For the air-fuel ratio control of natural gas engine, the closed-loop and self-learning control strategy based on wide range oxygen sensor, the automatic calibration system of ignition advance angle based on speed feedback, and the constant rotation control algorithm of CNG engine are proposed. The transfer function is identified for the relationship between rotational speed and throttle under different loads, and the feedback PID simulation control is studied. On the basis of analyzing the working principle of Bosch LSU4.2 wide range oxygen sensor, the closed loop and self learning control strategy of air fuel ratio (PID) based on wide domain oxygen feedback is designed to realize the effective control of air fuel ratio and help the calibration of jet MAP. The calibrator does not need to calibrate each operating point very accurately. The jet pulse width can be adjusted to a suitable value by means of closed-loop and self-learning while the engine is working, thus saving the calibration time of the jet MAP. At the same time, it can make up the air-fuel ratio offset caused by the aging of engine wear; the calibration system of ignition advance angle based on speed feedback can help the calibration of ignition MAP; the engine constant rotation control system is to expand the applicability of the control system. The PID control strategy is used to adjust the throttle opening in real time so that the rotational speed is always stable near the set target value. The simulation research of throttle and speed feedback PID control based on the model is to identify the transfer function of speed and throttle under different loads in advance, and then establish the feedback PID control model, so that the parameters of PID can be adjusted conveniently.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK402

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