Patent ID: 7750782

Claim:
An autotransformer for converting three-phase AC power to nine-phase AC power comprising: a first coil, a second coil and a third coil; each of said first, second and third coil containing serial windings and isolated windings; said serial windings and isolated windings being magnetically coupled; said serial and isolated windings on said first coil second coil and third coil containing a start end and a finish end such that current entering the start end produces a magnetic flux in one direction whereas a current entering the finish end produces a magnetic flux in the opposite direction; the finish end of a serial winding on the first coil being connected to the finish end of an isolated winding on the third coil with the start end of said isolated winding being connected to a series connection of three other isolated windings; the three other isolated windings being selected from the first coil, the second coil and the third coil and being arranged in a sequence of; first coil, second coil, third coil, or first coil, third coil, second coil, or second coil, first coil, third coil, or second coil, third coil, first coil, the end of the series connection of said three other isolated windings being connected to the start end of a serial winding on the second coil; said interconnections of windings being repeated sequentially for all three coils until all windings are interconnected to form a multi-sided polygon; said multiple interconnections of windings forming multiple multi-sided polygons; said multiple polygon topologies including symmetrically disposed nodes; wherein symmetrically disposed nodes provide points for applying three-phase AC input voltage and extracting AC output voltages of predetermined amplitude and phase.