Modeling and validation of a boost pressure actuation system,for a series sequentially turbocharged SI engine

An actuation system for flexible control of an advanced turbocharging system is studied. It incorporates a vacuum pump and tank that are connected to pulse width modulation controlled vacuum valves. A methodology for modeling the entire boost pressure actuation system is developed. Emphasis is placed on developing component models that are easily identified from measured data, without the need for expensive measurements.The models have physical interpretations that enable handling of varying surrounding conditions.The component models and integrated system are evaluated on a two stage series sequential turbo system with three actuators having different characteristics.Several applications of the developed system model are presented, including a nonlinear compensator for voltage disturbance rejection where the performance of the compensator is demonstrated on an engine in a test cell. The applicability of the complete system model for control and diagnosis of the vacuum system is also discussed.