Nonlinear MPC for a two-stage turbocharged gasoline engine airpath

Innovative charging concepts such as two-stage turbocharging for gasoline engines, cause high demands on the process control due to the complex, nonlinear system behavior. For complex, nonlinear systems Nonlinear Model-based Predictive Controllers (NMPC) offer a high potential. They are capable of handling coupled multiple-input systems while achieving high control quality and respecting constraints of the system. In the case of turbocharging, considerations to protect components can introduce the necessity to constrain certain system values. This paper presents a two-stage turbocharged gasoline airpath modeling approach which is suited to be used in a NMPC implementation. The control implementation is based on direct optimal control using an online Sequential Quadratic Programming (SQP) type algorithm. For validating the control performance, simulations are conducted. The computation time of the algorithm is determined by implementation on a control prototyping platform for validation of the real-time capability.