【作者】 王迪；

【导师】 李顶根；

【作者基本信息】 华中科技大学 ， 动力机械及工程， 2013， 硕士

【摘要】 均质压燃（HCCI）是均质混合气在压缩作用下的一种自燃过程，它能够显著改善发动机的燃油经济性、大幅度降低NOx排放，但是同时存在着燃烧控制困难、负荷范围有限以及瞬态工况不易控制等问题。本文主要通过数值模拟仿真的方法，围绕着HCCI燃烧控制问题进行研究。为了控制均质压燃（HCCI）发动机的峰值压力及燃烧相位，本文建立了压力、燃烧相位的两输入两输出的物理模型。基于Shaver提出的废气循环HCCI发动机物理模型，该模型加入了适用于HCCI燃烧模式的定壁温传热模型，抓住了HCCI发动机的热力过程以及循环耦合特性，并且精度在可允许的区间内，验证了该控制模型对于发动机控制系统设计的实用性。加入简化的化学动力学机理文件，在GT-POWER中建立了HCCI单缸发动机模型，将化学动力学与一维发动机软件相结合，燃烧放热率由所选取的反应机理文件通过化学动力学计算预测得出。采用模型预测控制（MPC)理论，设计了峰值压力及燃烧相位的协同控制器，将GT-POWER与MATLAB/SIMULINK两个软件耦合，搭建联合仿真平台。以可变气门正时（VVT）为控制手段，进行了GT-POWER与MATLAB/SIMULINK联合仿真实验。仿真结果显示：本文的MPC有良好的受限优化功能，压力控制精度在±30kPa以内，燃烧相位CA (AOP)控制精度在±0.6°以内，响应时间约0.4s（6～7个发动机循环），减少了缸内循环变动，并且能够实现燃烧相位以及压力的独立以及协同控制。更多还原

【Abstract】 Homogeneous charge compression ignition (HCCI) is the process in which ahomogeneous mixture is auto-ignited through compression. This combustion processhas advantages of low fuel consumption and ultra low NOx emission. However, thechallenges from the auto-ignition control difficulty and narrow operation region limitthe practical application of this technology. This paper is mainly to study the controlstrategies of the HCCI combustion through the numerical simulation method.A two-input and two-output physical model for peak pressures and combustionphases was built to realize the coordinated control of the peak pressures andcombustion phases of homogeneous charge compression ignition (HCCI) engines.This model was based on the Shaver’ residual-affected HCCI engine model and addedwith the constant wall temperature heat transfer model suitable for HCCI combustion.The HCCI engine thermal process and cycle to cycle coupling characteristics havebeen captured. Meanwhile the accuracy of the model have been verified. Thepracticality of the control model for engine control system design have beenvalidated.Joined a simplified chemical kinetics mechanism files, a single cylinder HCCIengine model have been established in the GT–POWER. The combustion heatrelease rate can be predicted by the reaction mechanism file through the chemicaldynamics calculation. By using model predictive control theory, a cooperative controlsystem of pressure and combustion phase was designed. The corresponding controleffect was obtained by using the coordinated simulation experiment of GT-POWERand MATLAB/SIMULINK with variable valve timing (VVT) as control method.The result shows that the physical-based model can satisfy the engine controldemand. This control system can reduce the cylinder cycle variation with goodrestricted optimization function. At the same time the model predictive control (MPC)controller realized the independent and collaborative control of the pressure andcombustion phase with the control accuracy of±30kPa and±0.6°CA，response time of about6~7engine cycles.更多还原