VSCF starter generator

Use of the same electrical machine for both starting an engine and then supplying electrical power is an old concept. The VSCF starter generator system is a modern mechanization of this idea. It is an all AC conversion system plus a wound rotor salient pole machine. During the start, the system functions as a brushless DC machine with 400 Hz supplied to it. After the start is completed, the output of the machine, now operating as a synchronous generator driven at variable speed, is converted to constant frequency (VSCF) 400 Hz power. No major power circuit changes are required to change mode.