We are getting into complicated areas where the slightest imconsistent word usage can change the whole meaning of the discussion.
There are true 2-phase systems where the phases are 90 deg apart from each other. Motors on these systems can create a large amount of torque, similar to DC. A (2) transformer Scott-Tee connections is used to convert 3-phase to 2-phase and 2-phase to 3-phase.
There is also a standard Tee transformer connection which is used for normal 3-phase to 3-phase voltage conversion.
In your case you are describing using 2 hot lines of a 3-phase system (The engineering equivalent circuit of 2 hot lines is a 1-phase system). You need some type of phase convertor system to go from 1-phase to 2-phase and finally to 3-phase. A "static" system would contain 1-phase capacitors to create a 4-wire 2-phase system and then a Scott-Tee transformer arrangement to provide the 2-phase to 3-phase conversion.
This type of phase conversion has some definite drawbacks (including effciencyand regulation) but it is better than nothing.
Hope this helps.
