SBIR Phase I: Semi-active magnetic bearing for flywheel energy storage systems

The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project is to implement a high-efficiency, low-power magnetic bearing that will enable the successful development of high-speed flywheel energy storage systems (FESS) both for space and terrestrial applications. FESS are mechanical batteries that overcome some of the limitations of lithium-ion batteries, such as the loss of energy capacity over time and the need for stringent temperature control. In space, FESS could reduce the overall mass associated with the battery pack and extend the mission life of Low Earth Orbit (LEO) satellites. On earth, FESS can take over some of the applications that are required to deliver high power for a short amount of time, such as electric vehicle charging stations or hospital back-up power units. Ultimately, FESS will help alleviate the demand for lithium-ion batteries while providing reliable, long-lasting energy storage. This Small Business Innovation Research (SBIR) Phase I project will demonstrate the feasibility of integrating the proposed magnetic bearing into a carbon-fiber flywheel. The complexity of this task comes from having the three main parts of the flywheel (composite rim, metal core, and magnets) created using different manufacturing processes. The magnetic materials need to be protected as they will not withstand the high speeds of FESS. De-risking this manufacturing process is crucial in continuing the development of this technology and in scaling up. Another challenge is that the high speeds of FESS are expected to cause high gyroscopic torques during satellite maneuvers. Therefore, investigating ways to increase bearing stiffness (e.g., by changing magnet size and position, or modifying coil shape), while assessing the effect of gyroscopic torques through numerical models, will be paramount. Finally, the magnetic bearing has the distinctive feature of being able to tilt the flywheel (within its gap tolerances), without requiring an external gimbal actuator. This feature could possibly allow the technology to be used for dual purposes, and its implications will be investigated at a system level. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.