Optimal Peak Pressure and Exhaust Temperature Tracking Control for a Two-Zone HCCI Engine Model with Mean Burn Duration

Combustion in HCCI engines depends on several parameters such as temperature, pressure, thermochemistry of the cylinder gases, etc. These variables affect the two significant combustion parameters: ignition timing and combustion duration. Controlling ignition timing and burn rate in such engines over a range of engine speeds and loads is an inherently challenging task. Existing single-zone HCCI engine-control models fail to accurately estimate the combustion parameters. Moreover, such models lacked the absolute dynamic control of all the valves. Although certain CFD based multi-zone models have been reported in literature, they are quite unwieldy for the development of fast and efficient HCCI-engine controllers. This paper outlines a physics-based two-zone model of an HCCI engine with an empirical mean burn duration model in order to better predict combustion parameters and facilitate controller development. The discrete nonlinear model is linearized about an operating point and the resulting linearized model is used to create an effective LQR-based tracking controller for peak pressure and exhaust gas temperature.