Those motors are more like a 3 phase motor than a 3 phase stepping motor. Step sequence would look like this = Windings A B & C - A+ BC-, AB+ C-, B+ AC-, BC+ A-, C+ AB-, AC+ B-, back to A+ BC-, Would require 6 transistors, 3 high side, and 3 Low Side. (actually 9 tansistors, 3 for current, and 3 to drive the power transistors). A 3Phase Bridge.