Virtual Exhaust-Gas Aftertreatment Test Bench - A Contribution to Model-Based Development and Calibration of Engine Control Algorithmsa 2012-01-0897

Introducing new exhaust-gas aftertreatment concepts at mass production level places exacting demands on the overall development process - from defining process engineering to developing and calibrating appropriate control-unit algorithms. Strategies for operating and controlling exhaust-gas aftertreatment components, such as oxidation and selective catalytic reduction catalysts (DOC and SCR), diesel particulate filters (DPF) and SCR on DPF systems (SCR/DPF), have a major influence on meeting statutory exhaust-emission standards. Therefore it is not only necessary to consider the physical behavior of individual components in the powertrain but also the way in which they interact as the basis for ensuring efficient operation of the overall system.

The following considerations aim to develop and calibrate simulation methods for exhaust-gas aftertreatment systems using IAV ANBsim with a focus on analyzing strategies for operating and controlling exhaust-gas aftertreatment systems on the basis of production control-unit algorithms implemented in a Rapid Prototyping environment. This approach enables the evaluation of operating and control strategies early on in the development process, supporting algorithm development.

For this purpose, real-time numerical models are generated for simulating the physical and chemical processes taking place in exhaust-gas catalytic converters or diesel particulate filters and integrated as system models in a HiL simulator (“hardware in the loop”) with control unit and production algorithm. This virtual test bench provides the capability of automatically simulating driving cycles, such as FTP75 and NEDC, while taking into account different calibrations. It also permits the analysis of the operating and control strategy impact on the tailpipe emissions. The effects of new algorithms can be studied directly.

By way of example, capabilities of the virtual test bench are discussed on the basis of an ammonia-metering strategy used by SCR catalyst and SCR/DPF systems. Analysis covers differently calibrated control parameters, providing a route to necessary extensions of the control-unit algorithms.