Model Predictive Controller with Average Emissions Constraints for Diesel Airpath

TL;DR

This paper introduces a model predictive control approach for diesel engines that optimizes fuel efficiency while satisfying average emissions constraints over a drive cycle, improving upon instantaneous constraint methods.

Contribution

It formulates an MPC that considers average emissions constraints, enabling better trade-offs between emissions and fuel economy in diesel airpath control.

Findings

Effective tracking of boost pressure and EGR rate.

Successful adherence to average emissions constraints.

Improved fuel efficiency demonstrated experimentally.

Abstract

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.