Model Predictive Control of a two-stage turbocharged Diesel engine air-path system for rapid catalyst warm-up

This paper presents the design of a model predictive controller for Diesel engine air-path system that coordinates the actuators of a two-stage turbocharger to reduce the aftertreatment warm-up time, optimizing the boost pressure and maintaining the desired EGR ratio. Starting from a control-oriented model of the engine air-path system, a bypass valve thermal model is derived to predict the temperature at the inlet of the Diesel Oxidation Catalyst. Then, a discrete-time piecewise affine system is obtained by combining the linearized model at different operating points. The rapid warm-up control problem is formulated as a tracking problem and solved by applying Model Predictive Control. The effects of different weights in cost function are evaluated to elucidate the trade-off between boost pressure and warm-up performance. Finally, a heuristic control for rapid warm-up is developed from the analysis of the simulation results with MPC.