Flywheel support system for mobile energy storage

Abstract

A flywheel support system isolates the flywheel and its motor-generator from the driving environment of an electrically powered motor vehicle. A suitable liquid, placed between the outer and vacuum housings of the flywheel assembly, provides buoyancy and damping to the vacuum housing, cooling of the motor-generator, and serves as one of the barriers to rotor energy and angular momentum transfer in the event of an accident or failure. During normal operation, a shearable mechanical gimbal system keeps the vacuum housing centered in the outer housing, reacts the spin moments generated by the motor-generator, and provides a path for the electrical leads into the vacuum housing. In the event of bearing seizure or rotor failure, the mechanical gimbal will shear and allow the vacuum housing to gradually spin down against the fluid. A system of both active and passive axial and radial magnetic bearings supports the rotating assembly including the rotor of the motor-generator. Rotor-stator gap proximity sensors, strategically placed along the axis, permit a minimum gap to be used in the motor-generator. The placement of the center of gravity of the vacuum housing and its contents below the center of buoyancy produces a vertical orientation of the housing in the absence of accelerations, thus minimizing the power consumed by the magnetic support system when the vehicle is parked.