| Internal combustion (IC) engines are optimized to meet exhaust emission requirements with the best fuel economy. Closed loop combustion control is a key technology that is used to optimize the engine combustion process to achieve this goal. In order to conduct research in the area of closed loop combustion control, a control oriented cycle-to-cycle engine model, containing engine combustion information for each individual engine cycle as a function of engine crank angle, is a necessity. In this research, the in-cylinder pressure of an IC engine is modeled using the mass fraction burned (MFB), which is represented by the Wiebe function. Using MFB, along with other engine control inputs, an engine in-cylinder pressure signal can be constructed as a function of crank angle over an engine operational map.;Air-to-fuel (A/F) ratio is the mass ratio of air to fuel trapped inside a cylinder before combustion begins, and it affects engine emissions, fuel economy, and other performances. In this research, a multi-input-multi-output sliding mode control scheme is used to simultaneously control the mass flow rate of both port fuel injection (PFI) and direct injection (DI) systems to regulate the A/F ratio and fuel ratio of PFI to DI to desired levels. The control target is to maintain the A/F ratio at stoichiometry and the fuel ratio to a desired value between zero and one. The performance of the sliding mode controller is compared with that of a baseline proportional, integral, and derivative (PID) controller. |
