Model-Based Mode Transition Control Between SI and HCCI Combustion

While the homogeneous charge compression ignition (HCCI) combustion has its advantages of high thermal efficiency with low emissions, its operational range is limited in both engine speed and load. To utilize the advantage of the HCCI combustion an HCCI capable SI (spark ignition) engine needs to be developed. One of the key challenges of developing such an engine is how to achieve smooth mode transition between SI and HCCI combustion, where the in-cylinder thermal conditions are quite different due to the distinct combustion characteristics. In this paper, an SI-HCCI mode transition control strategy was developed for an HCCI capable SI engine equipped with electrical variable valve timing (EVVT) systems with two step-lift valves and electronic throttle control (ETC) system, and the developed strategy was validated in hardware-in-the-loop (HIL) simulations. During the mode transition, a MAP (manifold air pressure) controller was used to track the desired intake manifold pressure for charge air management, and a fuel management controller is used to provide the desired engine torque. HIL simulation results show that the developed controller is able to achieve smooth combustion mode transition under unmodeled dynamics and external disturbance.