Abstract: The rise and fall of the rotating speed of the flywheel realize the storage and release of the electrical energy in a flywheel energy storage system. The rotor dynamics problems such as the natural whirl frequencies and the critical speeds and the rotor balancing are dealt with. The low cost hybrid support composed of the permanent magnetic bearing and the spiral groove hydrodynamic bearing is employed in the experiments which are proceeded to test the rotor strength and the characteristics of the charging and discharging of the flywheel energy storage system. The damping of the lower support is adjusted, the flywheel is balanced and the energy loss and the generating of the electricity are tested in the experiments. The flywheel reaches its deigned rotating speed of 42.0 kr/min and stores energy of 497 W·h. The usable electricity arrives at 290 W·h when the flywheel falls from 42.0 kr/min down to 13.8 kr/min.

Key words: Flywheel energy storage system, Rotor dynamics, Failure behavior, Fracture analysis, Process research, Self-piercing riveting, TA1 titanium alloy