Abstract: A novel energy storage flywheel system is proposed, which utilizes high-temperature superconducting (HTS) electromagnets and zero-flux coils.
flywheel energy storage system typically works by combining a high-strength, high-momentum rotor with a shaft-mounted motor/generator. This assembly is contained inside a vacuum / containment vessel and operates normally in a non-contact fashion with magnetic bearings acting as a suspension system.
The basic concept of a flywheel electrical system is noted in figure 1. Other common power electronic circuits invert power from the motor/generator to line voltages and frequencies. 1 Funded in part by the Energy Storage Systems Program of the U.S. Department Of Energy (DOE/ESS) through Sandia National Laboratories (SNL).
With the high energy requirement for the flywheel system, the bearing loss can be great enough to significantly reducing the overall system efficiency. The 5 kWh / 100 kW FESS utilizes the hybrid HTS magnetic bearings .
Recharging can be done with essentially the same power switching electronics that are used for the discharge, except that the timing of currents in the motor/generator stator windings is adjusted to push the flywheel back up to high speeds. Once at high speed, the flywheel system can idle thus storing energy and acting as a battery.
Boeing's efforts in flywheels have been partially supported by the U.S. Department of Energy, Offices of Energy Efficiency and Renewable Energy under the Cooperative Agreement DE-FC36-99G010825, Contract W-31-109-Eng-38, and Sandia National Laboratories Energy Storage Program Contract 24412.