Control basics of a flywheel-powered uninterruptible motor drive

Uninterruptible motor drives (UMDs) are essential in critical applications, such as pumping stations, conveyor systems, medical apparatus, etc. Thanks to their good specific power characteristics, flywheels as energy storage mediums can be used as short-term energy storage not only in uninterruptible power supplies (UPSs)and UMDs, but in many other applications, vehicular storage and power management in smart grids. Like double-layer capacitors, the flywheels help avoid over-sizing of conventional battery packs and have much better life expectancy. This paper describes energy exchange processes between the storage and an induction motor in a UMD system and addresses control strategies of generic flywheel storage unit connected to a DC link. Finally, simulation results are analyzed.