http://redlib.catsarch.i2p/user/Why-R-People-So-Dumb
You need at least 3 lines to produce multiple phases because it's the only way you can have multiple pairings AB, BC, or CA, even if you only have two windings in the transformer - i.e. AB and BA are the same phase, just measured backwards. Windings and position of the winding have nothing to do with discrete phases, it's simply how many connection points you have back to the supply, which relates to the windings on the stator.