Abstract: A control system for a self-excited alternator which includes an auxiliary winding adapted to supply excitation to the alternator field winding incorporates a circuit for supplementing field excitation when the available energy from the auxiliary winding is less than the desired magnitude of field excitation. The self-exciting a-c current from the auxiliary winding is coupled through a phase-controlled rectifier circuit to the alternator field winding. A secondary excitation source such as a battery is coupled to the alternator field winding through a chopper circuit. A regulating circuit is responsive to a field current reference signal for controlling the conduction of the phase controlled rectifier circuit and the chopper circuit in a manner to regulate the alternator field excitation to the desired value.