Cycle-to-Cycle Control of a Dual-Fuel HCCI Engine

A known problem of the HCCI engine is its lack of direct control andits requirements of feedback control. Today there exists severaldifferent means to control an HCCI engine, such as dual fuels,variable valve actuation, inlet temperature and compression ratio.Independent of actuation method a sensor is needed. In this paper weperform closed-loop control based on two different sensors, pressureand ion current sensor. Results showing that they give similar controlperformance within their operating range are presented.Also a comparison of two methods of designing HCCI timing controller,manual tuning and model based design is presented. A PIDcontroller is used as an example of a manually tuned controller. ALinear Quadratic Gaussian controller exemplifies model basedcontroller design. The models used in the design were estimated usingsystem identification methods.The system used in this paper performs control on cycle-to-cyclebasis. This leads to fast and robust control. Dual fuels withdifferent octane numbers were used to control the combustion timing.The engine was a 12 liter 6 cylinder heavy-duty diesel engine modifiedwith a port fuel injection system which has dual fuels connected.