A method and apparatus for operating a polyphase dc motor selectively in dual-coil or uni-coil commutation modes. The motor has a plurality of "Y" connected driving coils connected together at a center tap. Each driving coil has an input node at an end opposite the center tap, and is driven by a switch...http://www.google.com/patents/US5455885?utm_source=gb-gplus-sharePatent US5455885 - Method and apparatus for starting a sensorless polyphase DC motor in dual-coil mode and switching to single coil mode at speed
