Patent ID: 8242649
Filing Date: 2012-08-14
Classification: F16C,H02K,Y02E

Abstract:
1. A flywheel battery, for storing electric power from a DC power bus as kinetic energy and regenerating electric power with minimal losses, comprising: motor/generator means in a flywheel assembly, including poly-phase stator windings for conducting poly-phase sinusoidal currents, the windings formed from multi-strand insulated conductors for eddy blocking and bucking, cooperative with a juxtaposed alternated-pole permanent-magnet array affixed to rotor iron for providing radial flux that interacts with said currents, and rotor angle sensors each aligned with a respective stator winding phase, for providing poly-phase feedback signals that vary essentially sinusoidally with rotor angle; power interface electronics, with H-bridges connected to the DC power bus and to the poly-phase stator windings of the motor/generator, said electronics responsive to the rotor angle sensors and to the DC bus voltage, for controlling by pulse-width-modulation poly-phase current through the stator windings so its resultant magnetic field rotates synchronously with the rotor; a flywheel rotor having a vertical spin axis, supported by bearing means comprised of repelling annular axial-field magnets centered by two ceramic ball bearings, including axial preload springs that augment the axial support of said axial-field magnets, the rotor including rotary inertia for storing kinetic energy, plus rotor elements of the motor/generator; a vacuum enclosure, containing mounting therein for the flywheel assembly, and hermetic connections to the power interface electronics outside the enclosure; and a housing and support structure, for the vacuum enclosure and flywheel assembly therein; wherein said bearing means further comprises: a stationary annular permanent-magnet, affixed to a cylindrical support that maintains precise centering around a center shaft, within and supported by the vacuum enclosure, to provide an axial magnetic field uniform with rotor angle, beneath the rotor assembly; a like rotatable annular permanent-magnet, affixed to the rotor assembly and precisely centered around said center shaft by upper and lower ball bearings, this permanent-magnet juxtaposed above said stationary annular permanent-magnet, and having an opposing axial magnetic field so that the two magnets repel each other, to provide a stable axial lift force for supporting the flywheel assembly weight; a first ceramic ball bearing near the top of the rotor assembly, having a slip fit around the center shaft and its inner race, and a slip fit around its outer race with an axial restraint, so that the ball bearing can slide axially with the rotor while it maintains precise rotor centering and augments the rotor axial support; a first axially compressed annular spring to provide axial lift force to the first ball bearing inner race, for providing consistent axial preload and also for providing flexible rotor lift; a second like ceramic ball bearing near the bottom of the rotor assembly, having a slip fit around the center shaft and its inner race, and a slip fit around its outer race with an axial restraint, so that the bearing can slide axially with the rotor while it maintains precise rotor centering and augments the rotor axial support; and a second like annular spring to provide axial lift force to the second ball bearing inner race, for providing consistent axial preload and also for providing flexible rotor lift.