Semiconductor Power Converterless Voltage Sag Compensator and UPS Using a Flywheel Induction Motor and an Engine Generator

Flywheel energy storage systems are focused as uninterruptible power supplies (UPS) from the viewpoint of environmental friendliness and high durability performance. Using a low-speed, heavy, simple flywheel, and a low-cost squirrel-cage induction motor/generator, this paper proposes two applications as follows; 1) 11-kW voltage sag compensator using a capacitor self-excited induction generator without semiconductor converters; 2) UPS composed of the flywheel system and an engine generator. From some experimental results, an ideal voltage sag compensator and UPS are realized by the low-technology flywheel system.