From 11000 km test experience with a 26 kW powered electric car of 13 kWh range, the Heilbronn University team is convinced that electric car operation in mixed urban - regional areas is feasible today especially for commuter traffic. However, range is and will be an issue for all battery electric vehicles. In this paper, a fly-wheel range-extending approach is investigated by theoretical, simulation and laboratory research. Therefore, two new basic operation strategies are proposed. A "preview range extending" strategy consumes the precharged flywheel energy content early at the beginning of a travel not only for traction but also for heating and cooling purposes. This strategy compensates the effects of flywheel energy losses due to friction. The "fast recharging" strategy holds if unexpected range extensions occur. Here, the flywheel capability of multiple fast charging without reduction of lifetime is utilized. During further initial work, two basic research tracks for the flywheel dynamics are revealed, the flywheel mobile platform interaction track and the flywheel drive dynamics research track. For investigation of the mobile platform interaction a flywheel camera stabilization device in combination with an articulated robot was utilized. It serves to validate a scalable simulation model now available for a flywheel system with multiple hinge and wheel configurations. For further conceptual work on the university vehicle with supplemented flywheel, typical vehicle motions like yaw and roll and its interaction can be investigated. A stationary 70 kWs flywheel prototype with 15 kW motor/generator and power electronics unit has been designed in the flywheel drive dynamics research track. In parallel, a simulation model was established and validated with flywheel experiments up to 40 000 1/min. This scalable simulation model is now available to transfer multiple flywheel and motor/generator parameters for electric car adaption. First simulations including a first scaling with a flywheel energy content of 1.5 kWh shows that approximately 15 % of the typical urbanregional test cycles can be powered by the flywheel system. Further perennial research work based on these results will be supported by the state of Baden-Württemberg. It will focus on the configuration of flywheel mass, speed, diameter and hinge configuration in electric vehicle application at minimum friction costs.
Electric car operation and flywheel energy storage
2012
12 Seiten, 11 Bilder, 12 Quellen
Conference paper
English
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