A circuit is provided for use in a synchronous generator excitation system. The circuit comprises a three-phase bridge having six legs. The bridge is connected with an AC power supply. A thyristor is provided in each of the six legs, wherein the thyristors provide a path for a device current. A free wheeling diode functions as a de-excitation means connected in parallel with the three-phase bridge. The free wheeling diode provides a discharge path for a field current.
An exciter system for the field of a synchronous generator excitation is provided. The exciter system includes an AC power source; a three-phase thyristor bridge having six legs, the three-phase bridge being connectable with the AC power source, and being adapted to provide a variable DC voltage output; a thyristor in each of the six legs of the three-phase bridge, wherein the thyristors provide a path for a device current; and a three-phase AC line filter series, including series resistive and capacitive elements across each phase of the AC power source and a plurality of bleed resistors, wherein at least one bleed resistor is connected to each AC input connection of the filter.
