Use of a high performance Lithium iron phosphate battery in the fuel cell range extender vehicle concept

Kurzfassung

Electric vehicles are emission free due to independence from fossil fuels and it has great advantage of environmental sustainability. Under the pressure of stringent emissions legislation in the future, electrification of the drive train is an option in order to meet the emission standards law. Even though the battery technology has advanced greatly during the past decade, it still has some limitations. One limitation is the range, which would make only possible to use an electric vehicle in the urban traffic. An owner of a conventional vehicle is usually not having different vehicles for various applications such as driving to work, shopping, holidays, etc. In the case of the fuel cell range extender concept, as shown in figure 1, is an attractive way, which combine both technologies either permanently or on demand and also promotes the introduction of e-mobility as a sustainable vehicle concept. The on-board fuel cell charging system could also carry the tasks of heat management and the air conditioning, which requires new and innovative concepts, so that the range of the electric vehicle could be increased. In this mentioned range extender vehicle concept, the powertrain is driven mainly by the high performance Li-ion battery. In this project, the variant of lithium iron phosphate Li-FePO4 battery has been used. The on-board fuel cell range extender in this case serves as an additional source of energy unit, which charge the high-performance battery in a low SOC and therefore extend the range. The design of such a vehicle concept is nowadays trend of technology therefore a simulation tool plays a very important role, which allows the prediction of the design. The role of the battery as opposed to the conventional vehicle acts here as the main energy storage, and therefore a study of the essential behavior of the battery must be done. The modeling of the battery was performed partially map-based, which enables a simpler parameterization. Besides the energetic behavior, the thermal behavior also would be described in the model, which is completed by the measurement of the temperature dependent charge and discharge behavior. A comprehensive survey of the behavior of the battery could be done by the integration to the full vehicle model, which are included an on-board fuel cell range extender, power electronics, electric motor, drive train, chassis, and controller cycles. The simulation results could be used as a tool for optimum design for range extender vehicle concepts as shown in the figure 1. A final validation of the complete vehicle model would be done by comparison between the simulation results of the full vehicle model and the results of the driving behavior of the real prototype vehicle on chassis dynamometer.