Mr. Schneeweiss presented the work program of the Institute for Powertrains & Automotive Engineering (IFA) at the TU Vienna. After a general introduction, he first focused on the interface model. The major task of the interface is connecting the simulation model and the hardware ECU (see slide 10). The interface model is manufacturer specific and remains confidential, but must be disclosed to the approval authority. In case of multiple ECUs, the most important functions of less important control units could be implemented via the interface model of the HILS system, which is a kind of simplified software-in-the-loop.

The Japanese simulation model is realized with Simulink, a well established programming language, which is based on physical models and lookup tables (see slide 15). The most important model is the powertrain model (see slide 16). In Japan, five different powertrain models exist, but for a worldwide regulation more powertrain models would likely have to be developed. In order to solve this problem, IFA is proposing a component library. Components are physical entities (e.g. engine, motor-generator, battery, clutch, gearbox etc.) that are combined to result in a special powertrain topology. IFA also suggests to develop temperature models to take into account hybrid control strategies for optimized engine warmup. Prof. Hausberger added that this would also be needed for the warm-up of any aftertreatment system. The Chairman recalled that the WHDC procedure includes a cold start and a hot start test, and this issue must be dealt with in a global regulation. It was agreed that this could finally result in two different engine cycles for cold start and hot start.

The Chairman then raised the question where the models would be defined. It was general understanding that the gtr could only include some base models, like in Japan. Furthermore, it will not be possible to amend the gtr every time a new model is proposed by a manufacturer. The Secretary proposed an approach of defining in the gtr general guidelines of model construction on the basis of the component library proposed by IFA. With this approach, verification of the models becomes more important.

IFA then introduced an alternative to the Japanese vehicle based approach for consideration of the group. This alternative uses the premise that engine work of a conventional powertrain (on the WHTC) and of a hybrid powertrain (from HILS) should be comparable. The simulation would be done using the engine WHTC torque from WHTC speed input signal at the gearbox, as illustrated in slide 26. The approach is elaborated in more detail in working paper HDH-07-05rev by TU Graz.

IFA is proposing to do the model verification by comparing simulation results to actual measured data from test track driving using a random driving cycle. This is due to problems, which might occur in chassis dyno testing (correct recuperation, high cost).

IFA concluded that the Japanese component testing provisions could basically be used for a global regulation. Component testing strongly depends on the modeling depth and on the desired accuracy. Under this aspect, Mr. Jackson asked how the durability of the hybrid systems would be taken into account. This is currently not included in the Japanese regulation, but the Chairman emphasized that at least some aspects like durability of the storage system should be covered by the gtr.

Finally, Mr. Schneeweiss indicated that the final report would be issued by the end of 2011.