Prof. Hausberger (TU Graz) presented working paper HDH-09-06. He started with a summary of the conclusions from the 8th HDH meeting.

On page 5, he gave an overview of the different options for the determination of the HILS engine cycle on the basis of a simple serial hybrid. Option A corresponds to the Japanese method by using the vehicle cycle WHVC and generic vehicle data as input signals. Option B1 uses system power and engine rpm at the wheel hub as input signals while option B2 uses system power and engine rpm at the shaft as input signals. Both options are based on the engine cycle WHTC resulting in the World Heavy Duty Hybrid Cycle (WHDHC). Option B1 had already been presented in detail at the 8th meeting. Prof. Hausberger expressed some preference for option B2.

When using the WHDHC approach, it is required to normalize the negative (braking) power.

First, it was concluded that there is a good correlation between negative power and engine rated power (page 9). This was confirmed by Mr. Andreae. However, negative power is influenced by the vehicle category, which requires a correction factor (shown on page 11).

The complete normalization procedure is outlined on page 12.

Pages 14 to 18 show the comparison between the WHVC and WHDHC approach for a conventional powertrain. Three different vehicle categories of the Japanese regulation (T4, T6 and T7) were evaluated each with different power packs (240 kW, 3 different shapes of full load curve). The WHVC approach leads to engine loads and speed/load distributions that are quite different from the WHTC approach. Contrary to the WHTC approach, high powered vehicles virtually do not have high engine loads in a power pack cycle resulting from WHVC.

Options B1 (wheel hub cycle) and B2 (shaft cycle) are comparable, whereby option B2 seems to be the simpler method that also matches the WHTC for conventional engines. The advantages and disadvantages of the three options are summarized on page 19. A yet unresolved issue is the definition of the full load power curve for a hybrid powertrain.

As regards the evaluation of WHVC weighting factors, Prof. Hausberger reported that the definition of vehicle classes and CO2 test cycles within the EU CO2 program has not yet been finalized. Therefore, the evaluation is currently limited to city buses, as already presented at the 8th meeting and shown again on page 33. The final report will only include these results and the calculation method. The results with the other vehicle classes and cycles will be delivered to the HDH group later without additional cost.

The simulation of an air conditioning system of a city bus with respect to PTO load is shown on pages 36 to 41. It is concluded that influence of this PTO load on brake specific criteria pollutant emissions is low and should therefore not be added. PTO loads may be included in the CO2 test procedures. For a detailed AC simulation, an additional component “electric consumer” would have to be established within the HILS method. For other PTOs, “hydraulic consumer” and “mechanic consumer” might be added, accordingly.

Apart from the final evaluation of WHVC weighting factors, the program is on schedule.

Japan asked for clarification on the CO2 mandate. Harmonized CO2 test procedures for conventional vehicles should be first discussed at GRPE level. The Chairman responded that CO2 is within the mandate for hybrids, and that need to be taken into account when establishing general CO2 test procedures within GRPE, in the future.