Externally modulated independent speed variable frequency generator

• US 10,498,273 B2
• Filed: 04/23/2018
• Issued: 12/03/2019
• Est. Priority Date: 04/23/2018
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Gao, Lijun, Solodovnik, Eugene, Liu, Shengyi
• Primary Examiner(s): Gonzalez, Julio C.
• Application Number:
  US15/959,507
• Publication Number:
  US 20190326839A1
• Time in Patent Office: 589 Days
• Field of Search: 322 44, 322 28, 322 89
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: H02P 9/08 Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation
• CPC Class Codes: H02P 9/302 Brushless excitation
• CPC Class Codes: H02P 9/42 to obtain desired frequency without varying speed of the generator

Abstract

Described is an independent speed variable frequency generator system that may include a rotor and a stator. The system may further include a pilot generator stage including a magnetic field source positioned on the rotor and a set of pilot multiphase windings positioned on the stator. The system may also include a high frequency transformer stage including a first set of high frequency transformer multiphase windings positioned on the stator and a second set of high frequency transformer multiphase windings positioned on the rotor. The system may also include a main machine stage including a set of main field multiphase windings positioned on the rotor and a set of main armature multiphase windings positioned on the stator, where the second set of high frequency transformer multiphase windings are coupled directly to the set of main field multiphase windings. The system may include a generator control unit.

Claims

1. An independent speed variable frequency generator system comprising:

a rotor;

a stator;

a pilot generator stage including a magnetic field source positioned on the rotor and a set of pilot multiphase windings positioned on the stator;

a high frequency transformer stage including a first set of high frequency transformer multiphase windings positioned on the stator and a second set of high frequency transformer multiphase windings positioned on the rotor;

a main machine stage including a set of main field multiphase windings positioned on the rotor and a set of main armature multiphase windings positioned on the stator, wherein the second set of high frequency transformer multiphase windings are coupled directly to the set of main field multiphase windings;

a generator control unit;

a motor start driver; and

a switching circuit configured to open and close a connection between the set of main armature multiphase windings and a power distribution bus and to open and close a connection between the set of main armature multiphase windings and the motor start driver.

2. The system of claim 1, wherein the generator control unit comprises:

a multiphase inverter having a plurality of switching circuits; and

a controller circuit, an input of each of the plurality of switching circuits coupled to the controller circuit.

3. The system of claim 2, wherein, in a motor state, the controller circuit is configured to open each of the plurality of switching circuits to prevent output at the multiphase inverter.

4. The system of claim 2, wherein, in a power generation state, the controller circuit is configured to open and close the plurality of switching circuits in a pattern that generates a high frequency modulated multiphase power signal that includes a main field multiphase power signal component that is usable to drive the set of main field multiphase windings to create a rotating magnetic flux that rotates relative to the rotor.

5. The system of claim 4, further comprising:

a frequency sensor connected to an output of the multiphase inverter, wherein the controller circuit is configured to adjust a frequency of the main field multiphase power signal component based on a difference between a reference frequency and a main field frequency measured by the frequency sensor.

6. The system of claim 4, further comprising:

a voltage sensor connected to an output of the set of main armature multiphase windings, wherein the controller circuit is configured to adjust a voltage of the main field multiphase power signal component based on a difference between a reference voltage and an output voltage measured by the voltage sensor.

7. The system of claim 4, further comprising:

an encoder configured to detect a rotational frequency of the rotor, wherein the controller circuit is configured to adjust a frequency of the main field multiphase power signal component based on a difference between a reference frequency and a rotor frequency measured by the encoder.

8. The system of claim 1, further comprising:

an external power source; and

another switching circuit configured to open and close a connection between the pilot generator stage and the generator control unit and to open and close a connection between the external power source and the generator control unit.

9. A method for independent speed variable frequency power generation comprising:

generating a high frequency modulated multiphase power signal at a generator control unit positioned external to a rotor of an independent speed variable frequency generator, the high frequency modulated multiphase power signal including a main field multiphase power signal component, wherein generating the high frequency modulated multiphase power signal comprises opening and closing a plurality of switching circuits of a multiphase inverter in a pattern that generates the high frequency modulated multiphase power signal at a controller circuit of the generator control unit;

transmitting the high frequency multiphase power signal from a stator to the rotor of the independent speed variable frequency generator via a high frequency transformer stage;

generating an asynchronous rotating magnetic flux at a set of main field multiphase windings positioned on the rotor by applying the main field multiphase power signal component of the high frequency modulated multiphase power signal to the main field multiphase winding; and

converting the asynchronous rotating magnetic flux into a main machine multiphase power signal at a set of main armature multiphase windings positioned on the stator; and

before generating the high frequency modulated multiphase power signal;

connecting a motor start driver to the set of main armature multiphase windings;

opening the plurality of switching circuits to prevent output at the multiphase inverter; and

sending a current pattern from the motor start driver through the set of main armature multiphase windings to generate a rotating magnetic flux pattern that causes the rotor to turn, enabling startup of an engine.

10. The method of claim 9, further comprising:

connecting a set of pilot multiphase windings positioned on the stator to a multiphase rectifier of the generator control unit;

generating, at a magnetic field source positioned on the rotor, a synchronous rotating magnetic flux that rotates synchronously with the rotor;

converting the synchronous rotating magnetic flux into a pilot multiphase power signal using the set of pilot multiphase windings;

rectifying, at the generator control unit, the pilot multiphase power signal to generate a rectified power signal; and

using the rectified power signal to generate the high frequency modulated multiphase power signal.

11. The method of claim 9, further comprising:

connecting an external power source to the generator control unit; and

using a power signal from the external power source to generate the high frequency modulated multiphase power signal.

12. The method of claim 9, further comprising:

after startup of the engine, disconnecting the set of main armature multiphase windings from the motor start driver; and

connecting the set of main armature multiphase windings to a power distribution bus.

13. The method of claim 9, further comprising:

receiving a main field frequency signal;

receiving a reference frequency signal; and

adjusting a frequency of the main field multiphase power signal component of the high frequency modulated multiphase power signal based on a difference between the main field frequency signal and the reference frequency signal.

14. The method of claim 9, further comprising:

receiving an output voltage signal;

receiving a reference voltage signal; and

adjusting a voltage of the main field multiphase power signal component of the high frequency modulated multiphase power signal based on a difference between the reference voltage and the output voltage.

15. The method of claim 9, further comprising:

receiving a rotor frequency signal;

receiving a reference frequency signal; and

adjusting a frequency of the main field multiphase power signal component of the high frequency modulated multiphase power signal based on a difference between the rotor frequency signal and the reference frequency signal.

16. An independent speed variable frequency generator system comprising:

a rotor;

a stator;

a high frequency transformer stage including a first set of high frequency transformer multiphase windings positioned on the stator and a second set of high frequency transformer multiphase windings positioned on the rotor;

a main machine stage including a set of main field multiphase windings positioned on the rotor and a set of main armature multiphase windings positioned on the stator, wherein the second set of high frequency transformer multiphase windings is coupled directly to the set of main field multiphase windings;

a motor start driver; and

a switching circuit configured to open and close a connection between the set of main armature multiphase windings and a power distribution bus and to open and close a connection between the set of main armature multiphase windings and the motor start driver.

17. The system of claim 16, further comprising:

a generator control unit configured to generate a high frequency modulated multiphase power signal that includes a main field multiphase power signal component that is usable to drive the set of main field multiphase windings to create an asynchronous rotating magnetic flux that rotates relative to the rotor.

18. The system of claim 17, further comprising:

a pilot generator stage including a magnetic field source positioned on the rotor and a set of pilot multiphase windings positioned on the stator;

an external power source; and

another switching circuit configured to open and close a connection between the pilot generator stage and the generator control unit and to open and close a connection between the external power source and the generator control unit.

19. The system of claim 17, wherein the generator control unit comprises:

a multiphase inverter having a plurality of switching circuits; and

a controller circuit, an input of each of the plurality of switching circuits coupled to the controller circuit.

20. The system of claim 19, wherein, in a motor state, the controller circuit is configured to open each of the plurality of switching circuits to prevent output at the multiphase inverter.