An Energy Storage Flywheel Supported by Hybrid Bearings

Energy storage flywheels are important for energy recycling applications such as cranes, subway trains. In a petroleum field, a drilling platform runs with big load variation. A vertical flywheel energy storage system had been tested to stabilize the load fluctuation and proved its effectiveness. To improve bearing life and reliability, a new flywheel bearing system was designed. The key was the use of hybrid bearings including an axial permanent magnetic bearing (PMB), a lower end ball bearing and an upper end active magnetic bearing (AMB). The design effectively combined advantages of the different bearings. The original upper ball bearing was replaced with the AMB to avoid the use of a lubrication system for it and improve the damping ability for the rotor vibration modes. The vibration mode and the harmonic response were provided in the rotor dynamic analysis for the new flywheel rotor. The analysis results proved that the new rotor structure and the AMB design were appropriate.