SBIR Phase I: Robust Adaptive Levitation Control Technologies for High Speed, High Power Energy Storage Flywheels

This Small Business Innovation Research Phase I research project will develop advanced control techniques that will enable high-speed, high-efficiency operation of large-scale energy storage flywheels. A novel flywheel concept ? the ?Power Ring'' ? based on a hub-less rotor levitated and controlled by a hybrid magnetic bearing has been developed. The design and zero-speed levitation of the Power Ring have been demonstrated. Idle or ?spinning? losses are a key specification as they directly influence operational cost of the unit. Bearing losses are predicted to be 20% of the idle loss in the system. An advanced control system can reduce these losses by precisely monitoring and modifying the rotor vibrational modes as they sweep across the frequency band with changing machine speed. Modal control of the energy in individual vibration modes will give a highly efficient system that removes energy only from those modes that limit the machine operation. Advanced control will allow multi-megawatt devices with idle losses reduced by at least a factor of 2. A new control topology for the magnetic bearing that integrates robust control theory, modulated frequency control, on-line system identification, and adaptive control to create a reliable energy efficient levitation system will be developed. Electrical power quality problems have enormous economic impact. The Electric Power Research Institute estimates that power fluctuation and blackout losses exceed $100 billion/year. The majority of these problems are outages, surges, and sags lasting only a few seconds. The Power Ring flywheel is a cost effective method of maintaining power system stability by injecting stored energy back into the grid to carry the system through the disturbance. It can serve as a rapid-response energy storage device, allowing control of grid power flows and frequency, and enhancing grid stability and power quality/reliability. Flywheels are more efficient and less polluting than the current method of using idling power stations (typically coal-fired) to provide reserve for frequency regulation applications. Flywheels have a longer life, lower maintenance cost, and do not contain toxic chemicals as do battery storage systems for power quality applications. The high power density and cycle life of flywheels makes them an enabling technology for regenerative transportation applications. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).