Towards High Capacity HTS Flywheel Systems

Frank N. Werfel, Uta Floegel - Delor, Thomas Riedel,
Rolf Rothfeld, Dieter Wippich, Bernd Goebel, Gerhard Reiner (1), Niels Wehlau (1)

Abstract - ATZ and L-3 MM are currently mounting a compact designed flywheel energy storage system (FESS) with total magnetic bearing support. Final assembling and test operation is scheduled to be in autumn 2008. After calculations and experiments we decide to improve rotor stabilization by a stiffer geometry. In addition, two dynamical emergency bearings contribute to robust and safe flywheel operation in critical rpm situations. The planned energy capacity of 5 kWh is now obtained at about 8000 rpm while an increased capacity of 10 kWh will be stored at a speed of 10,000 rpm. The total weight of the flywheel unit is about 1200 kg plus power electronics and cooling system. The heavier 600 kg rotor causes new design and construction work in mechanical elements, magnetic support bearings, cooling and power electronics. Due to the here reported construction changes and increased rotor speed scaling even larger energy storage performance of 15 – 20 kWh seems achievable. ATZ and L-3 MM obtained a corresponding order to develop and deliver a 15 kWh / 400 kW HTS FESS for a Korean local grid UPS application.

Index Terms – Flywheel, energy storage, rotor dynamics

Manuscript received August, 19, 2008.Chicago, USA. The work was supported by the German VDI / BMBF under the contract number 13N 8737 and 13N8738 .
F. N. Werfel , U. Floegel - Delor, T. Riedel, R. Rothfeld, D. Wippich, and B. Goebel are with the Adelwitz Technologiezentrum GmbH (ATZ), Adelwitz, Germany, Phone +49 34222 45200, e-mail: werfel@t-online.de;
G. Reiner (1), N. Wehlau (1) are with the L-3 Communications Magnet-Motor GmbH, Petersbrunner Straße 2, 82319 Starnberg, Germany, Phone +49 8151 262 133, e-mail: gerhard.reiner@l-3com.com ; niels.wehlau@l-3com..com

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