Supplying a synchronous machine with an excitation current

A method for supplying at least one excitation winding of a rotor of a synchronous machine with an excitation current, the method comprising:

• generating a constant excitation three-phase voltage by a main excitation machine, a rotor of which is connected in a rotationally fixed manner to the rotor of the synchronous machine;
• generating the excitation current by rectifying the constant excitation three-phase voltage by an adjusting unit that is connected in a rotationally fixed manner to the rotor of the synchronous machine;
• and
• regulating a current intensity of the excitation current by the adjusting unit,
• wherein the constant excitation three-phase voltage is generated by regulating a supply of the main excitation machine with a rectified auxiliary excitation three-phase current generated by an auxiliary excitation machine by sensing an intensity of a magnetic flux generated between the rotor and a stator of the main excitation machine and controlling the rectified auxiliary excitation three-phase current in response to the sensed intensity of the magnetic flux such that the magnetic flux is held constant.

An improvement for a brushless excitation system of a generator, the brushless excitation system including a main excitation machine providing an excitation current to a rotor of the generator and an auxiliary excitation machine providing an excitation current to the main excitation machine, the improvement comprising:

• a means for measuring an intensity of a magnetic flux generated between a stator and a rotor of the main excitation machine;
• and
• a means for controlling the intensity of the magnetic flux responsive to an output of the means for measuring;
• wherein the means for measuring the intensity of the magnetic flux further comprises a flux sensing device disposed in the main excitation machine;
• and
• further comprising:
• a regulating unit connected to receive a signal from the flux sensing device and operable to control an auxiliary excitation direct current supplied by the auxiliary excitation machine to the main excitation machine in a manner responsive to the signal such that the intensity of the magnetic flux generated between the stator and the rotor of the main excitation machine remains constant.