In the VSS-120 flywheel power system, high-speed rotation is attributed to Pentadyne’s use of a 12-in. wide high-speed carbon composite flywheel. The flywheel is suspended within the module by five-axis active-magnetic bearings (see the figure).
The motor and bearing controller module senses the position of the flywheel and adjusts the fields on the magnetic bearings to ensure that the flywheel is fully levitated at all times. This action essentially eliminates friction losses while allowing for the extremely fast spin. The control electronics, which are critical to this effort, take advantage of computational processing power that was previously unattainable.
Another key to the flywheel’s performance, an integrated vacuum system, eliminates the need for a noisy external pump. The system is essentially silent except for periods when it’s delivering power. During those periods, users will hear some microphonics associated with the 15-kHz switching performed by the systems’ power-conversion circuitry. Elimination of a vacuum pump saves maintenance. At the same time, there are no bearings to replace.
The VSS-120’s unique failsafe mechanism dissipates failure energy internally within a liquid coolant. So unlike other flywheel power systems, the VSS-120 can be rolled into place and secured with small bolts or screws. This makes installation easier and lowers its cost.