First principle based control oriented model of a gasoline engine including multi-cylinder dynamics

Abstract

The growing complexity of vehicle powertrain systems and stringent emissions requirements placed on these systems has necessitated the introduction of accurate and generalizable engine models that will be suitable for control and diagnostics. A first principle based control oriented model of a multi-cylinder gasoline engine is developed and shown to be also suitable for fault diagnosis. This model takes into cylinder-to-cylinder behavior and spatial orientation while maintaining a simple structure suitable for real time control. A model of the torque production mechanism is coupled with an analytical cylinder pressure model to capture the engine torque. The model of the torque production mechanism is derived using the Constrained Lagrangian Equation of Motion and simplified to a form suitable for integration in an overall engine model. The analytical cylinder pressure model is taken from literature and extended to a four cylinder engine. While it is common to model torque production subsystem as a continuously operating volumetric pump, the methods used in this work allow details including angular speed fluctuations of the crankshaft to be captured. In addition, the engine model is able to describe the dynamics of the system under faultless as well as faulty conditions, which is demonstrated for misfire. The proposed model is also leveraged for a novel fault tolerant control framework and is tuned and successfully validated for a 1.3L four cylinder gasoline engine.