Anthemios Philemon Petridis

Residual Gas Fraction Measurement and Estimation on a Homogeneous Charge Compression Ignition Engine Utilizing the Negative Valve Overlap Strategy

This paper is concerned with the Residual Gas Fraction measurement and estimation on a Homogeneous Charge Compression Ignition (HCCI) engine. A novel incylinder gas sampling technique was employed to obtain cyclic dynamic measurements of CO2 concentration in the compression stroke and in combination with CO2 concentration measurements in the exhaust stroke, cyclic Residual Gas Fraction was measured. The measurements were compared to estimations from a physical, 4-cylinder, single-zone model of the HCCI cycle and good agreement was found in steady engine running conditions. Some form of oscillating behaviour that HCCI exhibits because of exhaust gas coupling was studied and the model was modified to simulate this behaviour.

Nonlinear M.I.S.O. direct-inverse compensation for robust performance speed control of an S.I. engine

Nonlinear inverse compensation is developed for an SI engine MISO system from an identified plant model. The proposed application of the inverse is similar to the use of inverse SISO systems in one of Horowitz’s nonlinear QFT methods. For robust control the nonlinearity is characterised as an unstructured uncertainty. The objective of the inverse system is linearisation to reduce the size of the uncertainty necessary to account for the system nonlinearity. An increase in achievable robust performance with any linear robust performance control design technique may then be obtained. The novel feature of the MISO strategies proposed is that they provide additional design control over the control efforts. The method is experimentally validated by application to the automotive SI engine idle speed control problem using an electric dynamometer.