A novel uninterruptible power supply using flywheel energy storage unit

A novel uninterruptible power supply (UPS) with a flywheel energy storage unit is presented. The UPS is composed of an AC/DC rectifier, a DC/AC inverter, a permanent magnet brushless DC motor, a motor converter and a flywheel energy storage unit. Firstly, main power circuit of the UPS and its flywheel energy storage unit are introduced. Then the control strategies of the flywheel charging/discharging and DC/AC converter are discussed in detail. In charging mode, the AC/DC rectifier and motor converter are used for brushless DC motor driver. In discharging mode, motor converter is for boosting the DC link voltage. In both modes, UPS can work in on-line or off-line mode. The flywheel energy storage unit, which takes place of the conventional chemical battery unit, has the advantages of free maintenance, long life and no pollution. Finally the experiment results testify the novel UPS has better character and dynamical response.