Master's Thesis Justus Voigt
Development of a Hardware-in-the-Loop Test Bench for Model Based Evaluation of Thermal Comfort in an Electric VehicleCopyright: EBC
Due to the progressive electrification of motor vehicle drive train systems, the efficiency of air conditioning plays a decisive role due to the lower amount of energy carried along. With increasing efficiency, there should be no reduction in the thermal comfort of the occupants in the vehicle at the same time.
In order to develop new control concepts and test modified hardware for electric vehicles, a Hardware-in-the-loop test bench is developed and validated by the author. The test bench consists of an existing climatic chamber and a vehicle cabin with an integrated HVAC unit. The originally battery-powered electric supply is realized via a controllable power supply unit, so that eventually different usage cycles can be mapped. The investigation focuses on the recording and evaluation of comfort relevant parameters in the interior of the vehicle cabin. With these parameters, thermal sensation and thermal comfort can be determined using various comfort models. In particular, this work focuses on the implementation of the programmable logic controller (PLC) and the coupling to a suitable comfort model for the real-time assessment of thermal comfort and the selection, and installation of required sensors. The PLC transfers the comfort relevant environmental parameters in the interior in real time to the comfort model. The model calculates the thermal sensation and thermal comfort locally resolved and emits and records them via the PLC.
Since, in contrast to buildings, strongly asymmetric climate conditions occur locally in the vehicle and also show temporal changes, especially at the beginning of the journey.
The selected comfort model is validated in the second part of the work in the context of test person examinations in connection with the developed test bench. A suitable test scenario for a battery-powered delivery vehicle will be developed and executed with test persons and depict the investigation objects’ asymmetry, transience, and cold temperature performance. The results show that the simulation accurately reflects the test persons’ evaluations for thermal sensation e.g. for the head and back. For other body parts, (e.g. lower legs and feet) there are major deviations between simulation and subject valuation. In order to explain the reasons for the deviations, the heat flow on the skin surface is analysed. Based on the results, suggestions for optimization are discussed.