A Compact HTS 5 kWh/250 kW Flywheel Energy Storage System

• Published in: IEEE transactions on applied superconductivity Vol. 17; no. 2; pp. 2138 - 2141
• Main Authors: Werfel, F.N., Floegel-Delor, U., Riedel, T., Rothfeld, R., Wippich, D., Goebel, B., Reiner, G., Wehlau, N.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Bearings; Damping; Design engineering; Design optimization; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Energy accumulation; Energy storage; Exact sciences and technology; flywheel; Flywheels; Generators; Heart; High temperature superconductors; HTS bearing; losses; Magnetic levitation; Miscellaneous; Motors; Operation. Load control. Reliability; Power networks and lines; Power quality; Rotors; stiffness; Uninterruptible power supply; Uninterruptible power systems; Various equipment and components; Damping; Prototype; Flywheel; Power supply; Energy storage system; losses; Optimization; Graphite fiber; Shaft; Energy quality; Electric motor; HTS bearing; High temperature superconductor; Electric generator; Permanent magnet generators; Permanent magnet motors; Compact design; Power electronics; stiffness; Rotor; High power; Friction; Magnetic bearing; Uninterruptible power supply; Dynamic stability; Eddy current; Service quality
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2007.899252

Flywheel energy storage systems (FESS) are expected to contribute to uninterruptible power supplies (UPS) and power quality tasks significantly. We present design and the component results of a compact 5 kWh/250 kW HTS flywheel whereby the rotor will be totally magnetically stabilized. The design is optimized for highly integrated functionality of rotor body, generator/motor and bearings. The heart of the FESS is an ironless high power PM generator/motor delivering 250 kW. An advanced flywheel body manufactured from graphite fiber is stabilized by two magnetic bearings. A prototype 200 mm HTS bearing has been constructed and tested up to a load of 1 ton axially and 0.47 ton radially capable to carry the rotor weight of about 0.5 t. With a coefficient of friction (COF) of about 10 -6 the rotational drag was low. A passive PM bearing giving 80 N/mm radial stiffness/per pole was studied. HTS-PM damping response dependent on the temperature shows Lehr factors of 5-10% damping between 50 and 80 K. Eddy current dampers could support rotor dynamic stability.