Nonlinear MPC for Transient Charging Pressure and EGR Rate Control for a Turbocharged SI Engine

Innovative air path concepts utilizing exhaust gas recirculation (EGR) for turbocharged gasoline engines show promising results to lower the CO
₂
and pollutant emissions. However, the increased complexity of such systems poses high demands on the process control. With the upcoming real-driving emission (RDE) legislation, accurately managing transient operation will be one of the major challenges for the application of these systems, as rapid changes in engine speed have a considerable influence on the boost pressure buildup as well as on the obtained EGR rate. This paper focuses on the simultaneous control of boost pressure and EGR rate for a two-stage turbocharged gasoline engine with low pressure EGR during highly transient engine operation. When accelerating a vehicle in low gears, the engine speed gradient is at its maximum. This causes the highest difficulty in adjusting the respective setpoints. To tackle this challenge, a data-based nonlinear model predictive controller is presented which explicitly considers the actual engine speed and its predicted future trajectory. After implementation of the new control system into the ECU of a prototype test vehicle, the validation of the control algorithms is done by conducting real-driving experiments on a test track.