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C. Schmiderer:
"Modellierung und Optimierung fluider Kühlverfahren für eine bestehende elektrische Maschine";
Supervisor: B. Geringer, W. Weissel; E 315 Institut für Fahrzeugantriebe und Automobiltechnik, 2011; final examination: 2011-01-27.

The global trend to improve the efficiency of a vehicle by electrifying the drive train is not limited to road cars any longer. The present thesis deals with the optimization of the cooling system for the electrical machines of the hybrid module in the GT3 R Hybrid racing car by Porsche.
In the theoretical part of this thesis the specific requirements for a hybrid system in a motorsport application as well as the functions and possibilities which can be put into realization with such a system are pointed out. The technical data of the vehicle is described, the layout and the components of the hybrid system are explained closely. Furthermore an overview of electrical machines for automotive applications and the mechanisms of heat transfer are given. Different cooling systems for such machines are presented and the most effective variant is selected on the basis of relevant criteria for the usage in the GT3 R Hybrid. In addition there is a survey of the existing possibilities for calculating and simulating the heat transfer inside electrical machines. In this context the software Motor-CAD is acknowledged as the most appropriate one for the analysis of the existing electrical machine.
The quality of the heat transfers of different cooling liquids on the basis of the calculated heat transfer coefficient between the fluid and the electrical machine is determined in the practical part of the thesis. Based on these results as well as further important aspects taken into account, the most efficient cooling liquid is selected. For the prediction of the temperatures inside the real machine, representative duty cycles are defined for the simulation model which was established for this thesis. On top of that, the necessary preconditions and assumptions to obtain proper results are stated. As a last step parameter variations are carried out on the established simulation model in order to identify the most influential physical and geometric parameters on the thermal behaviour of the machine. On the basis of these results recommendations for the ideal size of the examined parameters are given and options to improve the congruence between the simulation model and the actual machine are proposed.