Abstract: An improved flywheel system for storing energy and providing the stored energy includes a rotor on a centrally located shaft. The shaft is positioned through support bearings. A magnetic off-loader provides a magnetic force to move the shaft axially in regard to the bearings. A feedback control system, provided to reduce bearing loads on the bearing, comprises a sensor mounted in a bearing housing positioned to measure the distance of a gap between a top end of the shaft and a lower surface of the sensor. In response to changes in the distance the sensor sends an electrical signal to a controller which in turn provides variable electric current to the magnetic off-loader which then provides a magnetic lifting force to the rotor on the shaft to minimize bearing load.

Abstract: An electric machine comprises a rotor assembly and a stator assembly adjacent the rotor assembly. The stator assembly includes windings disposed around a plurality of teeth, with each phase of the winding including at least one pair of coils wrapped in opposite directions around adjacent teeth to induce mutual inductance between the coils when electrical current flows through the phase of the winding. The coils of different phases are be arranged to cancel magnetic coupling between the different phases. The winding arrangement provides a way to accomplish multiple, redundant, magnetically and electrically isolated windings with current limiting means in a single stator of an electric machine. The winding arrangements inherently provide an increase in mutual inductance and, therefore, an increase in impedance over that possible with prior art winding arrangements to limit the maximum short circuit current in the windings.