A. Amini, M. Mirzaei, R. Khoshbakhti Saray,
Volume 3, Issue 4 (12-2013)
Abstract
In spark ignition (SI) engines, the accurate control of air fuel ratio (AFR) in the stoichiometric value is
required to reduce emission and fuel consumption. The wide operating range, the inherent nonlinearities
and the modeling uncertainties of the engine system are the main difficulties arising in the design of AFR
controller. In this paper, an optimization-based nonlinear control law is analytically developed for the
injected fuel mass flow using the prediction of air fuel ratio response from a mean value engine model. The
controller accuracy is more increased without chattering by appending the integral feedback technique to
the design method. The simulation studies are carried out by applying severe changes in the throttle body
angle to evaluate the performance of the proposed controller with and without integral feedback. The
results show that the proposed controller is more effective than the conventional sliding mode controller in
regulating the AFR without chattering.
