System Identification of Homogeneous Charge Compression Ignition (HCCI) Engine Dynamics

Homogeneous Charge Compression Ignition (HCCI) combustion lacks direct ignition timing control, instead the auto ignition depends on the operating condition. Since auto ignition of a homogeneous mixture is very sensitive to operating condition a fast combustion timing control is necessary for reliable operation, the ignition timing control design requiring appropriate models and system output variables for its feedback design. This paper demonstrates the use of system modeling and identification as a means to find models relevant to the engine control. The identification methods used were various subspace-based methods. An LQG controller was designed based on the estimated models and tested on a six-cylinder heavy duty engine running in HCCI operation