Air Path Estimation for a Turbocharged SI Engine with Variable Valve Timing

In the context of increasingly stringent pollution standards, engine pollutant emission reduction is a great challenge for spark ignition (SI) engines. The very narrow operating zone of the three-way catalyst necessitates a good control of the air/fuel equivalence ratio and therefore a good estimation of the aspirated air mass. We consider in this study a turbocharged SI engine equipped with variable valve timing actuators (VVT). This device acts as a disturbance by impacting on the air mass flow through the inlet valves. This impact can be estimated from real-time measurement. Two observers of the aspirated air mass are then proposed in this paper. After proving convergence in the two cases, we carry out comparisons based on simulation results.