Converters for wind turbine generators

A system for converting an alternating current (AC) output from a generator of a wind turbine, the system comprising:

• a first rectifier and a second rectifier of the wind turbine, each rectifier connected to the AC output of the generator and arranged to generate a respective direct current (DC) output, wherein:
• a positive DC level output from the first rectifier is applied to a first, positive DC conductor;
• a negative DC level output from the first rectifier is connected together with a positive DC level output from the second rectifier and applied to a second, neutral DC conductor;
• and
• a negative DC level output from the second rectifier is applied to a third, negative DC conductor, the first, second, and third DC conductors being arranged to transmit the resulting DC voltages;
• a first inverter configured to convert the DC output of the first rectifier to a first AC output having a predetermined frequency and voltage;
• a second inverter configured to convert the DC output of the second rectifier to a second AC output having a predetermined frequency and voltage, wherein the first AC output is configured to supply power to auxiliary circuits of the wind turbine such that the power available for delivery from the first AC output to an electrical grid is less than the power available for delivery from the second AC output;
• and
• a controller configured to, responsive to a measurement of the power supplied to the auxiliary circuits, control at least one of the first rectifier, the second rectifier, the first inverter, and the second inverter to improve a balance of AC power levels supplied to the electrical grid from the first AC output and the second AC output.

A system for converting an alternating current (AC) output from a generator of a wind turbine, the system comprising:

• a first rectifier and a second rectifier of the wind turbine, each rectifier connected to the AC output of the generator and arranged to generate a respective direct current (DC) output, wherein:
• a positive DC level output from the first rectifier is applied to a first, positive DC conductor;
• a negative DC level output from the first rectifier is connected together with a positive DC level output from the second rectifier and applied to a second, neutral DC conductor;
• and
• a negative DC level output from the second rectifier is applied to a third, negative DC conductor, the first, second, and third DC conductors being arranged to transmit the resulting DC voltages;
• a first inverter configured to convert the DC output of the first rectifier to a first AC output having a predetermined frequency and voltage;
• and
• a second inverter configured to convert the DC output of the second rectifier to a second AC output having a predetermined frequency and voltage,
• wherein a respective switched resistance is provided across DC terminals of each of the first rectifier, the second rectifier, the first inverter, and the second inverter, wherein magnitudes of the switched resistances of the first inverter and the second inverter are substantially greater than magnitudes of the switched resistances of the first rectifier and the second rectifier.