# US 10,320,314 B2 · Systems and methods for reducing effects of torsional oscillation for electrical power generation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,320,314 B2 - Document ID: US10320314B2 - Status: Granted - Kind: B2 - Application number: 15/582,421 - Filed: 2017-04-28 - Published: 2018-11-01 - Granted: 2019-06-11 - Earliest claimed: 2017-04-28 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Michael T. Fox; Kamiar J. Karimi; Sheau-Wei J. Fu; Eugene V. Solodovnik; Paul A. Mezs; Jerry E. Farstad - Web page: https://patentgrep.com/patent/US10320314B2 ## CPC - H02P 9/10: Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load - B64D 41/00: Power installations for auxiliary purposes - H02P 9/105: {for increasing the stability} - H03B 1/04: Reducing undesired oscillations, e.g. harmonics - B64D 2221/00: Electric power distribution systems onboard aircraft - G01H 1/10: of torsional vibrations - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H) - G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES ## Abstract Systems and methods are provided for an aircraft propulsor configured to generate electrical power through a variable frequency generator in response to rotation of a gear train. The aircraft propulsor includes compensation circuitry. The aircraft propulsor further includes exciter circuitry that, when powered by an excitation signal, generates a magnetic field that interacts with a rotating variable frequency generator to generate electrical power. The exciter circuitry may be powered by at least a portion of the power generated by the variable frequency generator. The compensation circuitry may adjust the excitation signal to reduce the effect of torsional oscillation of the gear train and/or the variable frequency generator on the quality of power produced by the variable frequency generator. ## Claims ### Claim 1 An aircraft propulsor comprising: a variable frequency generator coupled to a gear train, wherein the gear train has an associated torsional oscillation frequency; exciter circuitry to induce a magnetic field in the variable frequency generator in response to an excitation signal to generate electrical power by the variable frequency generator in response to rotation of the gear train; and compensation circuitry electrically coupled to the exciter circuitry, wherein the compensation circuitry comprises a controller that adjusts, independent of movement of the variable frequency generator and based on one or more characteristics of the gear train, the excitation signal in accordance with a predetermined frequency range to filter effects of the torsional oscillation frequency of the gear train in the electrical power provided by the variable frequency generator; wherein the one or more characteristics are stored in a memory of the compensation circuitry, and wherein at least one of the characteristics is associated with the torsional oscillation frequency. ### Claim 2 (depends on 1) The aircraft propulsor of claim 1, wherein an adjusted magnetic field induced in the variable frequency generator in response to the adjusted excitation signal performs notch filtering on the electrical power generated in response to the rotation of the gear train. ### Claim 3 (depends on 1) The aircraft propulsor of claim 1, wherein the effects of the torsional oscillation frequency comprise sub-synchronous oscillations of the gear train. ### Claim 4 (depends on 1) The aircraft propulsor of claim 1, wherein the controller is configured to perform a bench testing operation to determine the one or more characteristics by operating the exciter circuitry to selectively filter the electrical power over a plurality of possible torsional oscillation frequencies to identify the torsional oscillation frequency associated with the gear train. ### Claim 5 (depends on 1) The aircraft propulsor of claim 1, wherein the associated torsional oscillation frequency comprises a natural frequency of the gear train. ### Claim 6 (depends on 1) The aircraft propulsor of claim 1, wherein the exciter circuitry comprises an exciter electrically coupled to a field coil to provide current to the field coil in response to the excitation signal to induce the magnetic field. ### Claim 7 (depends on 1) The aircraft propulsor of claim 1, further comprising: a power unit; and the gear train coupling the power unit to the variable frequency generator, wherein the gear train is a direct drive gear train. ### Claim 8 A method of operating a power unit of an aircraft propulsor, the method comprising: rotating a variable frequency generator with a gear train, wherein the gear train has an associated torsional oscillation frequency; inducing a magnetic field in the variable frequency generator with exciter circuitry in response to an excitation signal; generating electrical power with the variable frequency generator and receiving the electrical power with compensation circuitry; adjusting, independent of movement of the variable frequency generator and based on one or more stored characteristics of the gear train, the excitation signal with compensation circuitry in accordance with a predetermined frequency range, wherein at least one of the characteristics is associated with the torsional oscillation frequency; and applying the adjusted excitation signal to the exciter circuitry to filter effects of the torsional oscillation frequency of the gear train in the electrical power provided by the variable frequency generator. ### Claim 9 (depends on 8) The method of claim 8, wherein an adjusted magnetic field induced in the variable frequency generator in response to the adjusted excitation signal performs notch filtering on the electrical power generated in response to the rotation of the gear train. ### Claim 10 (depends on 8) The method of claim 8, wherein the effects of the torsional oscillation frequency comprise sub-synchronous oscillations of the gear train. ### Claim 11 (depends on 8) The method of claim 8, further comprising performing a bench testing operation to determine the one or more characteristics by operating the exciter circuitry to selectively filter the electrical power over a plurality of possible torsional oscillation frequencies to identify the torsional oscillation frequency associated with the gear train. ### Claim 12 (depends on 8) The method of claim 8, wherein the associated torsional oscillation frequency comprises a natural frequency of the gear train. ### Claim 13 (depends on 8) The method of claim 8, wherein the exciter circuitry comprises an exciter electrically coupled to a field coil to provide current to the field coil in response to the excitation signal to induce the magnetic field. ### Claim 14 (depends on 8) The method of claim 8, wherein a power unit rotates the gear train to rotate the variable frequency generator, and wherein the gear train is a direct drive gear train. ### Claim 15 An aircraft comprising: a fuselage; a wing; and an aircraft propulsor coupled to the fuselage and/or the wing, the aircraft propulsor comprising: a power unit, a gear train coupled to the power unit, wherein the gear train has an associated torsional oscillation frequency, a variable frequency generator coupled to the gear train, exciter circuitry to induce a magnetic field in the variable frequency generator in response to an excitation signal to generate electrical power by the variable frequency generator in response to rotation of the gear train, and compensation circuitry electrically coupled to the exciter circuitry, wherein the compensation circuitry comprises a controller that adjusts, independent of movement of the variable frequency generator and based on one or more characteristics of the gear train, the excitation signal in accordance with a predetermined frequency range to filter effects of the torsional oscillation frequency of the gear train in the electrical power provided by the variable frequency generator, wherein the one or more characteristics are stored in a memory of the compensation circuitry, and wherein at least one of the characteristics is associated with the torsional oscillation frequency. ### Claim 16 (depends on 15) The aircraft of claim 15, wherein an adjusted magnetic field induced in the variable frequency generator in response to the adjusted excitation signal performs notch filtering on the electrical power generated in response to the rotation of the gear train.