Hardware-In-the-Loop (HIL) Modeling and Simulation for Diesel Aftertreatment Controls Devlopment

Lean NOx Trap (LNT) based aftertreatment system is an efficient way to reduce NOx emission from diesel engines. From control system perspective, the main challenge in aftertreatment system is to predict temperature at various locations and estimate the stored NOx in LNT. Accurate estimation of temperatures and NOx stored in the LNT will result in an efficient system control with less fuel penalty while still maintaining the emission requirements. The optimization of the controls will prolong the lifespan of the system by avoiding overheating the catalysts, and slow the progressive process of component aging.

Under real world conditions, it is quite difficult and costly to test the performance of a such complex controller by using only vehicle tests and engine cells. Hardware In the Loop Simulation (HILS) becomes very important and convenient in such cases to test the Electronic Control Unit (ECU), to develop algorithms and even tune the controller. The HILS can serve as a virtual engine cell to validate various diagnostics/control algorithms to the extreme conditions during the development phase. It can also be used to test software and hardware (ECU) both on components and system levels, pre-calibrate controls parameters etc. In general HILS testing saves lots of time & costs during the development of complex controllers.

In this paper, we discuss the modeling approaches as well as simulation procedures used for the aftertreatment project, the system model includes engine, doser, reformer, Lean NOx trap (LNT), Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR). We will also share some of the validation and testing results as well as how the HILS is used in aftertreatment controls development.