Excitation control system for rotating electrical apparatus

An excitation control system for a rotating electrical apparatus, said rotating electrical apparatus including an output having a plurality of alternating current phases and an input having an excitation voltage, said output for providing power to a power circuit, said excitation control system comprising:

• a transformer including a plurality of primary windings interconnected with said alternating current phases and also including a plurality of secondary windings having a plurality of alternating current phases each of which has a positive polarity and a negative polarity;
• at least one controlled rectifier bridge each of which includes .an input interconnected with the alternating current phases of the secondary windings of said transformer, an output interconnected with the input of said rotating electrical apparatus in order to provide said excitation voltage thereto, and a segment for each of said positive and negative polarities of the alternating current phases of the secondary windings, each of said segments having an element responsive to a control signal in order to control current conduction within said segment between the input and the output of said controlled rectifier bridge;
• means for regulating the output of said rotating electrical apparatus, said means for regulating including an output having a signal which requests a maximum value of said excitation voltage for said rotating electrical apparatus;
• means for connecting and disconnecting the output of said rotating electrical apparatus to said power circuit, said means for connecting and disconnecting including an output having a signal which indicates that said rotating electrical apparatus is connected to said power circuit;
• means for providing an error signal from the alternating current phases of the secondary windings of said transformer;
• and
• means for outputting the control signals to said segments in order to control current conduction within said segments, said means for outputting including means for repetitively and simultaneously outputting the control signals to each of said segments in response to:
• (a) said error signal exceeding a predetermined value, (b) the output of said means for regulating having the signal which requests the maximum value of said excitation voltage for said rotating electrical apparatus, and (c) the output of said means for connecting and disconnecting having the signal which indicates that said rotating electrical apparatus is connected to said power circuit, in order that said controlled rectifier bridge emulates a diode bridge.