A control apparatus (202) for a starter/generator (110) of an aircraft electrical power system is provided. During a start mode of operation, AC power is provided by the control apparatus (202) to an exciter stator (114) of the starter/generator (110) which is combined with controlled AC power supplied by a start converter (106) to a main stator (116) of the starter/generator (110) to rotate and start an aircraft engine. Alternatively, during a generate mode of operation after engine start, the control apparatus (202) provides DC power to the starter/generator (110) to produce a regulated voltage output from the starter/generator (110).