Three plus three phase flywheel power supply

A flywheel power supply comprising:

• a synchronous reluctance motor-generator including a rotor and a stator;
• a flywheel mass located within an evacuated containment;
• the flywheel mass coupled to and constrained to rotate in synchrony with the rotor;
• the flywheel mass bi-directionally exchanging mechanical power with the motor-generator;
• a plurality of windings on the stator forming six electrical phases A, B, C, D, E and F;
• one or more stator windings bi-directionally exchanging electric power with one or more AC to DC converters;
• and,
• one of the AC to DC converters coupled to an electrical network for providing backup power to the electrical network.