Magnetically coupled flywheel

Abstract

A stabilization system for a rotating load, such as a flywheel, includes a mechanical bearing to continuously support a shaft of the rotating load so as to hold the shaft at a substantially fixed axis of rotation. A magnetic stabilization assembly includes a plurality of electromagnets arranged around the shaft. Control circuitry for controls a resultant magnetic field generated by the electromagnets such that the magnetic field acts on a ferromagnetic element of the shaft to reduce imbalance forces acting on the shaft.

1 . A flywheel energy storage system for storing electrical energy, the system comprising:
 a plurality of flywheels;   a plurality of motor/generator units, each motor/generator unit of the plurality of motor/generator units coupled to a flywheel of the plurality of flywheels;   a plurality of controller/inverters, each controller/inverter being electrically coupled to a motor/generator unit of the plurality of motor/generator units;   a direct current (DC) bus electrically coupled to the plurality of controller/inverters and to a main inverter; and   a central controller to control each controller/inverter of the plurality of controller/inverters so as to set a discharge rate for each of the flywheels when its motor/generator unit is operating in a discharge mode, and to increase a voltage level of a voltage signal generated by that motor/generator unit when operating in the discharge mode and fed into the DC bus.   
     
     
         2 . The system of  claim 1 , wherein a controller/inverter of said plurality of controller/inverter comprises a bridge circuit and a pulse-width modulation controller. 
     
     
         3 . The system of  claim 2 , wherein the pulse-width modulation controller comprises an H-bridge circuit and a pulse-width modulation circuit. 
     
     
         4 . The system of  claim 1 , wherein the central controller is configured to control a controller/inverter of said plurality of controller/inverters to operate in a discharge mode while concurrently controlling another controller/inverter of said plurality of controller/inverters to operate in a charge mode. 
     
     
         5 . The system of  claim 1 , wherein the main inverter is coupled to the DC bus and to an alternating current power grid. 
     
     
         6 . The system of  claim 1 , wherein the DC bus comprises a constant voltage DC bus. 
     
     
         7 . The system of  claim 1 , wherein the DC bus is a high voltage DC bus operating at a voltage of at least 400V. 
     
     
         8 . The system of  claim 7 , wherein an operating voltage of the high voltage DC bus is between 400V and 1000 V. 
     
     
         9 . The system of  claim 8 , wherein the source controller is in communication with the central controller.