Cycle-to-cycle modeling and sliding mode control of blended-fuel HCCI engine

•Presents the first physics-based control model for “PRF blended-fuel” HCCI engines.•Provides a control model that can be utilized for real-time HCCI control.•Validates the new model with different transient fueling experimental data.•Illustrates the first application of Discrete Sliding Mode Control for HCCI engines.•Provides a HCCI combustion controller with strong disturbance rejection properties.

Fast and robust control of combustion phasing is an important challenge for real-time model-based control of Homogenous Charge Compression Ignition (HCCI). In this paper a new discrete Control Oriented Model (COM) for predicting HCCI combustion phasing on a cycle-to-cycle basis is outlined and validated against experimental data from a single cylinder Ricardo engine. The COM has sufficient accuracy for real-time HCCI control and can be implemented in real-time.A Discrete Sliding Mode Controller (DSMC) coupled with a Kalman filter is designed to control combustion phasing by adjusting the ratio of two Primary Reference Fuels (PRFs). The results indicate the DSMC maintains the stability of the engine operation in a wide range of loads and speeds. The DSMC is compared with an empirical Proportional Integral (PI) controller. The results show the SMC outperforms a PI controller particularly in rejecting disturbances while maintaining HCCI combustion phasing in its desired range.