Model Predictive Controller with Average Emissions Constraints for Diesel Airpath
For diesel engine control engineers, this work addresses the practical need to comply with legislated emissions standards that are averaged over a drive cycle, potentially improving fuel efficiency.
This paper proposes a model predictive controller for diesel airpath that enforces average emissions constraints over a drive cycle rather than instantaneous limits, enabling better fuel economy while meeting emissions standards. Experimental results on the new European drive cycle demonstrate tracking performance and constraint satisfaction.
Diesel airpath controllers are required to deliver good tracking performance whilst satisfying operational constraints and physical limitations of the actuators. Due to explicit constraint handling capabilities, model predictive controllers (MPC) have been successfully deployed in diesel airpath applications. Previous MPC implementations have considered instantaneous constraints on engine-out emissions in order to meet legislated emissions regulations. However, the emissions standards are specified over a drive cycle, and hence, can be satisfied on average rather than just instantaneously, potentially allowing the controller to exploit the trade-off between emissions and fuel economy. In this work, an MPC is formulated to maximise the fuel efficiency whilst tracking boost pressure and exhaust gas recirculation (EGR) rate references, and in the face of uncertainties, adhering to the input, safety constraints and constraints on emissions averaged over some finite time period. The tracking performance and satisfaction of average emissions constraints using the proposed controller are demonstrated through an experimental study considering the new European drive cycle.