Hardware-in-the-Loop Based Virtual Emission Calibration for a Gasoline Engine

In the field of gasoline powertrain calibration, the challenges are growing due to ever shorter time-to-market requirements and a simultaneous increase in powertrain complexity. In addition, the great variety of vehicle variants requires an increasing number of prototypes for calibration and validation tasks within the framework of the current Real Driving Emissions (RDE) regulations and the expected Post Euro 6 emission standards. Hardware-in-the-Loop (HiL) simulations have been introduced successfully to support the calibration tasks in parallel to the conventional vehicle development activities. The HiL approach enables a more reliable compliance with emission limits and improves the quality of calibrations, while reducing the number of prototype vehicles, test resources and thus overall development costs.

This paper introduces a novel Engine Control Unit (ECU) HiL simulation platform with a GT-Power based crank-angle resolved real-time engine model as well as a GT-Suite based real-time engine-out emission and exhaust after treatment system (EATS) models. To develop the new method, the basic GT simulation models were extensively used during the concept phase of a new powertrain and then further re-fined during the vehicle development process to allow virtual calibration. The coupling of the respective models and the hardware ECU is realized via a real-time workstation with a co-simulation platform (xMOD) and a HiL-simulator with the necessary I/O boards (dSPACE). In order to prove the emission calibration capability of the new HiL platform, the ECU function responsible for catalyst purging was exemplarily calibrated on the HiL test bench and compared with the final calibration of the real vehicle. Catalyst purging functionalities have a significant emission impact and their calibration is a cost and time intensive task. The maximum deviation between the simulated tailpipe emissions and the vehicle measurements during drive cycle operation is found to be within +/- 10%. By shifting the respective calibration task to the HiL platform, a total of 20 % of the development costs could be saved and only 50 % of the chassis dynamometer resources were required compared to a conventional approach.