Adaptive control of homogeneous charge compression ignition (HCCI) engines

This paper presents an adaptive controller which maintains consistent ignition timing control of a gasoline homogeneous charge compression ignition (HCCI) engine with high dilution in the presence of uncertainty or unknown variation in plant parameters such as exhaust runner wall temperature and cylinder charge properties. The control of the combustion timing is based on manipulating the charge temperature through internal dilution, which is achieved by controlling the lift of a secondary opening of the exhaust valve, also known as the rebreathing lift. The adaptive controller is designed based on a simplified bilinear parametric model which contains only the cycle-to-cycle combustion timing dynamics. Implementation of the designed adaptive controller requires feedforward information of the injected fuel and feedback information of the combustion timings when 50% and 90% of energy is released. It is shown through convergence analysis and closed-loop simulation of a full-order engine model that the adaptive controller is able to drive the combustion timing CA₅₀ to desired set-points by stabilizing the bilinear dynamics when plant parameters are changing.