Nine-phase transformer

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

• a. providing an autotransformer having 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 ninth 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 40 degrees and the voltage magnitudes at the output nodes are essentially identical;
• b. linking the first, second and third supply lines to a first input set including first, second and third input nodes between adjacent windings, respectively, the input nodes separated by 120 degrees and having essentially identical voltage magnitudes, each of the first, second and third input node voltage magnitudes less than each output node voltage magnitudes;
• c. linking the first through ninth output lines to the first through ninth output nodes, respectively;
• and
• d. providing the three-phase AC power to the first through third input nodes such that the autotransformer operates as step-up transformer.

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

• a. 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;
• b. a step-up input set including first, second and third input nodes between adjacent windings and separated by 120 degrees, the first, second and third input nodes linkable to the first, second and third supply lines, respectively;
• c. a unity gain input set including fourth, fifth and sixth input nodes between adjacent windings and separated by 120 degrees, the fourth, fifth and sixth input nodes linkable to the first, second and third supply lines, respectively;
• d. first through ninth output nodes between adjacent windings which are linkable to the first through ninth output lines, respectively;
• e. wherein, the voltage magnitude at each of the 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 40 degrees, the voltage magnitudes at each of the output nodes are essentially identical, the voltage magnitudes at each of the step-up input set nodes are essentially identical and each step-up input node voltage magnitude is less than each output node voltage magnitude such that when the supply lines are linked to the step-up input set the transformer can be used as a step-up transformer and the voltage magnitude at each of the unity gain input set nodes are essentially identical and each unity gain input node voltage magnitude is essentially identical to each output node voltage magnitude such that when the supply lines are linked to the unity gain input set the transformer can be used as a unity gain transformer.

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

• a. a primary including first, second and third primary coils configured so as to be separated by 120 degrees phase shift and forming first, second and third input nodes, the first, second and third input nodes linkable to the first, second and third supply lines, respectively;
• b. a secondary including:
• (i) first, second and third secondary coils arranged such that there is 120 degree phase shift between coils, each coil including a plurality of serial windings linked together at secondary nodes to form a polygon, the first second and third secondary coils in phase with the first, second and third primary coils, respectively;
• and
• (ii) first through ninth output nodes between adjacent windings which are linkable to the first through ninth output lines, respectively;
• c. wherein, the voltage magnitude at each of the 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 40 degrees, the voltage magnitudes at each of the output nodes are essentially identical and at least a sub-set of the secondary nodes have magnitudes less than the output node magnitudes.

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

• a. providing a transformer having a primary and a secondary, the primary including first, second and third primary coils linked together to form three input nodes and so that the coils are 120 degrees out of phase, the secondary including first, second and third secondary coils that are in phase with the first, second and third primary coils, respectively, each secondary coil having a plurality of serial windings linked together to form a polygon having secondary nodes between adjacent windings, the nodes including at least first through ninth 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 40 degrees, the voltage magnitudes at the output nodes are essentially identical and the voltage magnitudes of at least a sub-set of the secondary nodes are less than the output node magnitudes;
• b. linking the first, second and third supply lines to the first, second and third input nodes, respectively;
• c. linking the first through ninth output lines to the first through ninth output nodes, respectively;
• and
• c. providing the three-phase AC power to the first through third input nodes such that the transformer transforms the three phase input voltage to nine phase output voltage.