Controlling the Power Output and Combustion Phasing in an HCCI Engine

Abstract

In development of Homogeneous Charge Compression Ignition (HCCI) engines, simultaneous control of combustion phasing and power output has been a major challenge. In this study, a new strategy is developed to control the engine power output and combustion phasing at any desired operating condition. A single zone thermodynamic model coupled to a full kinetic mechanism of Primary Reference Fuels (PRFs) is developed to predict characteristic parameters such as; Start of Combustion (SOC) and Indicated Mean Effective Pressure (IMEP) and also thermodynamic constant parameters for processes through an HCCI engine cycle. A dynamic interactive control model has been developed for the entire cycle of a HCCI engine to predict combustion phasing and IMEP.The results derived from the developed model are validated against experimental data for a single cylinder Ricardo engine. A two input - two output controller is then designed to track crank angle at which 50% of in cylinder fuel mass is burned (CA50) and IMEP by adjusting the input data. In this study two control models are presented; open loop and closed loop. Performance of the controller is tested on a physical HCCI engine model to evaluate the tracking performance and disturbance rejection properties. Results indicate that the designed controller is capable to accurately track both CA50 and IMEP while can reject the disturbances from variations in the engine speed and the intake manifold temperature.