Design, Fabrication, and Test of a 5-kWh/100-kW Flywheel Energy Storage Utilizing a High-Temperature Superconducting Bearing

The Boeing team has designed, fabricated, and is currently testing a 5-kWh/100-kW flywheel energy-storage system (FESS) utilizing a high-temperature superconducting (HTS) bearing suspension/damping system. Primary design features include: a robust rotor design utilizing a composite rim combined with a metallic hub to create a 164-kg rotor assembly without critical resonances within the normal operating range, a closed-loop passive HTS bearing suspension/damping system, and a brushless 100-kW motor/generator. The Boeing FESS provides true isolation for the critical load as the 3-phase 480-V AC input power is converted to 600-V DC and re-inverted to clean, 3-phase 480-V AC output power by the inverter power electronics. When fully charged, the system is capable of responding within 4 ms for the uninterruptible protection of critical digital loads. Low losses and stable operation were demonstrated at rotational speeds exceeding 15,000 rpm.