Multivariable Control Of Residual-affected HCCI Engines Based On Model Predictive Control

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.