High performance and long life uninterruptible power source using a flywheel energy storage unit

The development of a flywheel uninterruptible power supply incorporating electrolytic capacitorless inverters and converters, optocouplerless power device drive circuits, loss reduction of high-frequency insulated-gate bipolar transistor (IGBT) inverters, and high-response regeneration control of the induction motor is described. Results from experiments performed on a three-phase, 5 kVA uninterruptible power source show that the system provides over 15 years of life, 100% input power factor, a 1% output voltage distortion, and a 93.4% efficiency.<>