Model-based Feedback Control for an Automated Transfer out of Si Operation during Si to Hcci Transitions in Gasoline Engines

This paper takes a first step towards model-based feedback control for the transition between spark ignition (SI) and homogeneous charge compression ignition (HCCI) combustion modes by approaching the transfer out of SI operation during the SI into HCCI transition in a closed-loop control framework. The combustion mode switch is taken to be directly from SI to HCCI without an intermediate combustion mode between the two, and the HCCI phase of the transition is not addressed. The transfer out of SI operation is formulated as a multi-input, multi-output control problem with input and output constraints. A baseline feedback controller for the transfer is designed using linear quadratic regulator methods, and is tested in simulation on a nonlinear mean value engine model. A simple open-loop transition based on look-up table set points is included as well for comparison. The feedback controller shows the ability to complete the SI phase of the transition in a short number of cycles, while maintaining a minimal disturbance to the engine torque in comparison to the open-loop controller.