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 is required. One of the key challenges of developing such an engine is to achieve smooth mode transition between SI and HCCI combustion, where the in-cylinder thermal and charge mixture properties are quite different due to the distinct combustion characteristics. In this research, mode transition between SI and HCCI combustion was investigated for an HCCI capable SI engine equipped with electrical variable valve timing (EVVT) systems, dual-lift valves and electronic throttle control (ETC) system. For the purpose of reducing research cost and development duration, one of the most efficient approaches is to develop and validate the control strategy using an HIL (hardware-in-the-loop) simulation environment, where the real engine is replaced by a control-oriented real-time engine model. This dissertation describes a two-zone HCCI combustion model, where the in-cylinder charge is divided into the well-mixed and unmixed zones as the result of charge mixing. Simplified fluid dynamics is used to predict the residual gas fraction before the combustion phase starts, which defines the mass of the unmixed zone, during real-time simulations. The unmixed zone size not only determines how well the in-cylinder charge is mixed, which affects the start of HCCI combustion, but also the resulting peak in-cylinder pressure and temperature during the combustion process. The developed model was validated in the HIL simulation and experiments.To achieve smooth combustion mode transition, the throttle position needs to be controlled accurately with fast response. In this dissertation, an electronic throttle control (ETC) system was modeled as an LPV (linear parameter varying) system in discrete-time domain, where the nonlinearities are modeled as varying parameter or compensated through feed-forward control. Mixed constrained H2/Hinf LPV controller was designed to achieve the best performance and also guarantee the system robustness. Then a model-based mode transition control strategy between SI and HCCI combustion was developed and experimentally validated for an HCCI capable SI engine equipped with electrical variable valve timing (EVVT) systems, dual-lift valves and ETC system. During the mode transition, a manifold air pressure controller was used to track the desired intake manifold pressure for managing the charge air; and an iterative learning fuel mass controller, combined with sensitivity-based compensation, was used to manage the engine torque in terms of net effective mean pressure, an indicator of engine output torque, at the desired level for smooth mode transition. Experiment results show that the developed controller is able to achieve smooth combustion mode transition with guaranteed robustness.
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