Nonlinear internal model controller design for wastegate control of a turbocharged gasoline engine

This work investigates the design of nonlinear internal model control (IMC) for wastegate control of a turbocharged gasoline engine. We extend the inverse-based IMC design for linear time-invariant (LTI) systems to nonlinear systems. To leverage the available tools for LTI IMC deign, we have explored the quasi linear parameter varying (quasi-LPV) model. IMC design through transfer function inverse of the quasi-LPV model is ruled out due to parameter variability. A new approach for nonlinear inverse, referred to as the structured quasi-LPV model inverse, is developed and validated. A fourth-order nonlinear model which sufficiently describes the dynamic behavior of the turbocharged engine is implemented to serve as the model in the IMC structure. The controller based on structured quasi-LPV model inverse is designed to achieve boost pressure tracking. Finally, simulations on a validated high fidelity model are carried out to show the feasibility of the IMC. Its closed-loop performance and robustness are compared with a well-tuned PI controller with extensive feedforward and anti-windup built in.