Adaptive Control of a Recompression Four-Cylinder HCCI Engine

An adaptive controller is presented for the control of combustion phasing in a multicylinder homogeneous charge compression ignition engine. Adaptive parameter estimation is used to modify a model-based feedforward controller for each cylinder´s start of injection (SOI) timing in an effort to mitigate model errors and increase the feedforward control accuracy. In-cylinder pressure measurements are used to calculate combustion phasing, which is compared with the prediction of an online nonlinear engine model to drive the parameter estimation that adapts the feedforward controller. It is demonstrated through experiments that the adaptive parameter can reduce the parameterization effort by allowing the model to adapt and match the response of each cylinder. It is also shown that the adaptive feedforward control is more accurate in the sense that load transitions can be achieved with less correction from the feedback controller. Overall, an average reduction of 41% in the absolute value of the SOI feedback component at steady state is achieved.