Patent ID: 8294429

Claim:
A voltage control system comprising: a digital voltage regulator enabled and configured to produce a digital gating signal to modulate a field current; an analog voltage regulator, pre-set disabled and configured to produce an analog modulating signal to modulate the field current; a selector switch coupled between the digital voltage regulator and the analog voltage regulator, wherein the selector switch is configured to cease a transmission of the digital gating signal from the digital voltage regulator upon detection of an upsetting event in the digital voltage regulator and further configured to enable transmission of the analog modulating signal from the analog voltage regulator to a field current switch modulating the field current; a gate driver connected to the selector switch, wherein the gate driver is configured to transmit the digital gating signal to the field current switch under uninterrupted operating conditions and to transmit the analog modulating signal to the field current switch during the detection of the upsetting event; and a driver module connected to the analog voltage regulator configured to send a command to the selector switch to close a line contact to the analog voltage regulator during the detection of the upsetting event.