A Disturbance Rejection-based Control Framework for SI-CAI Hybrid Combustion in Gasoline Engines

The SI-CAI (Spark ignited-controlled auto-ignition) hybrid combustion is promising in achieving smooth transition between SI and CAI combustion, but it is challenging to control due to its high sensitivity to boundary conditions. In this paper, a disturbance rejection-based control framework is proposed for the SI-CAI hybrid combustion. The complexity, nonlinearity and cross-coupling inside are stripped away by idealizing the combustion process into three decoupled integrators, for the combustion timing channel, the IMEP channel and λ channel respectively. All other dynamics that deviate from the integrators, internal and external, are lumped as "total disturbance" for each channel. With the total disturbances estimated and cancelled in real-time via three extended state observers, the enforced plant, i.e. the parallel integrators, is controlled by three proportional controllers. To further enhance the response and reject the time-varying uncertainties, a feedforward controller assisted by parameters on-line correction controller is added as a complementary. Simulation validation confirms the superiority of the proposed framework in terms of transient response, parameter tuning, robustness, and the adaptability.