An optimization method of LNT aftertreatment system based on discrete approximation

Abstract

This paper presents an optimal control design approach for LNT aftertreatment system in diesel engines. First, based on the observation of physics of the system, a dynamical model is constructed to represent the NOx reduction behavior under the air-fuel ratio changes. Then, the optimal control problem is formulated as a nonlinear dynamics-constrained optimization problem with a cost function that targets the NOx reduction with trade-off between fuel consumption and emission reduction. A numerical approximation algorithm is proposed to solve the optimization problem. Finally, the validation results with the simulation model with the identified physical parameters are illustrated to compare with the conventional rule-based approach.

Keywords

• automobile
• internal combustion engine
• modeling
• optimal control
• numerical calculation