Twelve-phase transformer configuration

A method for converting three-phase AC power provided on first, second and third supply lines to twelve-phase stepped down AC power on first through twelfth output lines, the method comprising the steps of:

• a. providing an autotransformer having only first, second and third coils, each coil having a plurality of serial windings linked together to form a polygon having nodes between adjacent windings, the nodes including at least first through twelfth output nodes, node voltage magnitudes measured by vectors between a neutral point and each node, the windings sized and arranged such that the phase shift between adjacent output nodes is essentially 30 degrees and the voltage magnitudes at the output nodes are essentially identical;
• b. linking the first, second and third supply lines to first, second and third input nodes between adjacent windings, respectively, the input nodes separated by 120 degrees and having essentially identical voltage magnitudes;
• c. linking the first through twelfth output lines to the first through twelfth output nodes, respectively;
• and
• d. providing the three-phase AC power to the first through third input nodes.

An isolation transformer for converting three-phase AC power provided on first, second and third supply lines to twelve-phase AC power on first through twelfth output lines, the autotransformer comprising:

• a. a primary including first, second and third primary coils configured so as to be separated by 120 degrees and forming first, second and third input nodes, the first, second and third input nodes linkable to first, second and third supply lines, respectively;
• b. a secondary including:
• (i) only first, second and third coils arranged such that there is 120 degree phase shift between coils, each coil including a plurality of serial windings linked together to form a polygon;
• and
• (ii) first through twelfth output nodes between adjacent windings which are linkable to the first through twelfth output lines, respectively;
• (iii) wherein, the voltage magnitude at each of the output nodes is measured by a vector between a neutral point and the node, the windings are sized and arranged such that the phase shift between adjacent output nodes is essentially 30 degrees and the voltage magnitudes at each of the output nodes are essentially identical.