# US 7,466,109 B1 · Systems and methods involving variable speed generators > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,466,109 B1 - Document ID: US7466109B1 - Status: Granted - Kind: B1 - Application number: 12/098,585 - Filed: 2008-04-07 - Granted: 2008-12-16 - Earliest claimed: 2008-04-07 - Assignees: General Electric Company - Inventors: Einar Vaughn Larsen; James Michael Fogarty; Cyrus David Harbourt - Web page: https://patentgrep.com/patent/US7466109B1 ## CPC - H02P 9/007: {Control circuits for doubly fed generators} - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract An electrical generation system comprising a generator. The generator including, a stator portion, and a rotor portion, and a variable frequency generator (VFG) exciter. The VFG exciter including, a first converter, operative to convert DC current to AC current connected to a DC link and a second converter, operative to convert DC current to AC current connected to the DC link. The system including a first switch operative, when closed, to connect the first converter to the stator portion while the generator is operating in a starting condition, wherein the first switch is open while the generator is operating in a running condition. The system including second switch operative, when closed, to connect the first converter and the second converter in parallel to the rotor portion while the generator is operating in a running condition, wherein the second switch is open while the generator is operating in the starting condition. ## Claims ### Claim 1 An electrical generation system comprising: a generator, wherein the generator includes: a stator portion; and a rotor portion; a variable frequency generator (VFG) exciter, wherein the VFG exciter includes: a first converter, operative to convert DC current to AC current connected to a DC link; and a second converter, operative to convert DC current to AC current connected to the DC link; a first switch operative, when closed, to connect the first converter to the stator portion while the generator is operating in a starting condition, wherein the first switch is open while the generator is operating in a running condition; and a second switch operative, when closed, to connect the first converter and the second converter in parallel, to the rotor portion while the generator is operating in the running condition, wherein the second switch is open while the generator is operating in the starting condition. ### Claim 2 (depends on 1) The electrical generation system of claim 1, wherein the VFG exciter further comprises a third converter operative receive an AC current from an AC source, convert the AC to a DC current, and send the DC current to the DC link. ### Claim 3 (depends on 2) The electrical generation system of claim 2, wherein the third converter is further operative to transform a first AC voltage from the AC source to a second AC voltage. ### Claim 4 (depends on 1) The electrical generation system of claim 1, wherein the VFG exciter further comprises: a dynamic brake and a dynamic brake resistor, operative to protect the exciter during a grid fault. ### Claim 5 (depends on 1) The electrical generation system of claim 1, wherein the first switch and the second switch are located in the VFG exciter. ### Claim 6 (depends on 1) The electrical generation system of claim 1, further comprising harmonic filters connected to the rotor. ### Claim 7 (depends on 1) The electrical generation system of claim 1, further comprising a tertiary winding on a generator step up portion, wherein the tertiary winding is operative to receive an output power from the stator portion, transform the output power voltage, and send the output power to a power grid. ### Claim 8 (depends on 7) The electrical generation system of claim 7, wherein the tertiary winding is further operative to send a second output power to a second voltage output. ### Claim 9 (depends on 8) The electrical generation system of claim 8, further comprising harmonic filters connected to the second voltage output. ### Claim 10 (depends on 2) The electrical generation system of claim 2, wherein the AC source is a second voltage output. ### Claim 11 (depends on 2) The electrical generation system of claim 2, wherein the AC source is a power grid. ### Claim 12 (depends on 1) The electrical generation system of claim 1, further comprising a gas turbine generator. ### Claim 13 A variable frequency generator (VFG) exciter comprising: a first converter, operative to convert DC current to AC current connected to a DC link; and a second converter, operative to convert DC current to AC current connected to the DC link, wherein the second converter is electrically connected to a generator rotor; a first switch operative, when closed, to connect the first converter to a stator portion while a generator is operating in a starting condition, wherein the first switch is open while the generator is operating in a running condition; and a second switch operative, when closed, to connect the first converter and the second converter in parallel, to the rotor portion while the generator is operating in a running condition, wherein the second switch is open while the generator is operating in the starting condition. ### Claim 14 A method for starting and operating a VFG system, the method comprising: closing a first switch, wherein the closed first switch is operative to connect a first converter to a stator of a generator; starting the first converter, wherein the first converter is operative to convert DC power to AC power and control the stator; starting a second converter, wherein the second converter is electrically connected to a rotor, and is operative to convert DC power to AC power and control the rotor; starting a generator; opening the first switch, thereby disconnected the first converter from the stator; closing a second switch, wherein closing the second switch connects the first converter and the second converter in parallel; and controlling the first converter and the second converter to operate in parallel to send power to the rotor.