In-cylinder oxygen mass fraction cycle-by-cycle estimation via a lyapunov-based observer design

This paper presents a nonlinear observer design for cycle-by-cycle estimation of the in-cylinder oxygen mass fraction at the intake valve closing (IVC) for Diesel engines equipped with exhaust gas recirculation (EGR) systems. Such an observer can provide critical in-cylinder condition information for control of combustion, particularly advanced combustion modes on a cycle-by-cycle basis. The stability of the observer was shown through a Lyapunov analysis based on a mean-value model. Simulations based on a high-fidelity, computational, GT-Power engine model exhibited that the observer can effectively estimate the in-cylinder oxygen mass fraction at IVC on a cycle-by-cycle basis at both steady-state and transient operating conditions.