GENERATOR CONTROL CIRCUIT

• US 20090058373A1
• Filed: 08/30/2007
• Published: 03/05/2009
• Est. Priority Date: 08/30/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Graovac, Dusan, Auer, Frank
• Granted Patent: US 7,759,909 B2
• Time in Patent Office: Days
• US Class Current: 322/25
• CPC Class Codes: H02P 2101/30 for aircraft
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence

Abstract

A generator control circuit is disclosed. One embodiment provides a first active switching circuit configured to connect a first terminal of an excitation coil either to a first or to a second terminal of a voltage source, a second active switching circuit configured to connect a second terminal of the excitation coil either to the first or to the second terminal of the voltage source, and a generator controller to set the duty cycle of the active switching circuit to rapidly control the current through the excitation coil to an excitation coil current setpoint.

Claims

1. An control circuit comprising:

a first active switching circuit to connect a first terminal of an excitation coil either to a first or to a second terminal of a voltage source;

a second active switching circuit to connect a second terminal of the excitation coil either to the first or to the second terminal of the voltage source; and

a generator controller to set the duty cycle of the first and/or second active switching circuit to rapidly control the current through the excitation coil to an excitation coil current setpoint.

2. The control circuit of claim 1, wherein the first and/or second active switching circuit comprises a two quadrant chopping circuit.

3. The control circuit of claim 1, wherein the generator controller comprises a first control loop to control the excitation coil current.

4. The control circuit of claim 3, wherein the first control loop comprises:

a first current measuring device configured to measure the excitation coil current as input to a first signal conditioning device to generate a first feedback signal to be subtracted from the excitation coil current setpoint as input to a current controller to generate a pulse width modulation (PWM) control signal as input to a PWM generator to generate a driver control signal as input to a driver circuit coupled to the first and/or second active switching circuit to control the duty cycle of the first and/or second active switching circuit.

5. The control circuit of claim 3, wherein the generator controller further comprises a second control loop to control an rectified output voltage of the generator to a rectified generator output voltage setpoint.

6. The control circuit of claim 5, wherein the second control loop comprises:

a voltage measuring device configured to measure the rectified output voltage of the generator as input to a second signal conditioning device to generate a second feedback signal to be subtracted from the rectified generator output voltage setpoint as input to a voltage controller to generate the excitation coil current setpoint.

7. The control circuit of claim 6, wherein the second control loop further comprises a second current measuring device for measuring a rectified output current of the generator as further input to the second signal conditioning device.

8. The control circuit of claim 6, wherein the second control loop further comprises a frequency measuring device for measuring the frequency of an ac generator output voltage as further input to the second signal conditioning device.

9. The control circuit of claim 8, wherein the second signal conditioning device further generates a rate of change with time of the frequency of the ac generator output voltage as part of the second feedback signal.

10. The control circuit of claim 2, wherein the two quadrant chopping circuit comprises at least two N-Channel MOSFET transistors.

11. The control circuit of claim 2, wherein the two quadrant chopping circuit comprises at least two insulated-gate bipolar transistors (IGBTs).

12. A control circuit comprising:

a first active switching circuit which can be coupled between a first terminal of a voltage source and a first terminal of the excitation coil;

a second active switching circuit which can be coupled between a second terminal of the voltage source and a second terminal of the excitation coil;

a first freewheeling diode which can be coupled between the second terminal of the voltage source and the first terminal of the excitation coil;

a second freewheeling diode which can be coupled between the first terminal of the voltage source and the second terminal of the excitation coil; and

a generator controller coupled to the first and/or second active switching circuit and adapted to set the duty cycle of the first and/or second active switching circuit.

13. The control circuit of claim 12, wherein the first and/or second active switching circuit comprises at least two N-Channel MOSFET transistors.

14. The control circuit of claim 12, wherein the first and/or second active switching circuit comprises at least two insulated-gate bipolar transistors (IGBTs).

15. The control circuit of claim 12, wherein first active switching circuit comprises at least one P-Channel MOSFET.

16. The control circuit of claim 12, wherein the first control loop comprises:

a first current measuring circuit configured to measure the excitation coil current as input to a first signal conditioner to generate a first feedback signal to be subtracted from the excitation coil current setpoint as input to a current controller to generate a PWM control signal as input to a PWM generator to generate a driver control signal as input to a driver circuit coupled to the first and/or second active switching circuit to control the duty cycle of the first and/or second active switching circuit.

17. The control circuit of claim 12, wherein the generator controller further comprises a second control loop to control a rectified generator output voltage to a rectified generator output voltage setpoint.

18. The control circuit of claim 17, wherein the second control loop comprises:

a voltage measuring circuit configured to measure the rectified generator output voltage as input to a second signal conditioner to generate a second feedback signal to be subtracted from the rectified generator output voltage setpoint as input to a voltage controller to generate the excitation coil current setpoint.

19. The control circuit of claim 18, wherein the second control loop further comprises a second current measuring circuit for measuring a rectified generator output current as further input to the second signal conditioner.

20. The control circuit of claim 18, wherein the second control loop further comprises a frequency measuring circuit for measuring the number of revolutions of the generator or the frequency of an ac generator output voltage as further input to the second signal conditioner, and wherein the second signal conditioner further generates the rate of change with time of the frequency of the ac generator output voltage as part of the second feedback signal.

21. A generator assembly, comprising:

a two quadrant chopping circuit to connect a first and a second terminal of an excitation coil independently either to a first or to a second terminal of a voltage source; and

a generator controller to set the duty cycle of the two quadrant chopping circuit to control a current through the excitation coil to an excitation coil current setpoint to excite a generator to generate an ac generator output voltage as input to a rectifier to generate a rectified generator output voltage.

22. The generator assembly of claim 21, comprising:

a generator coupled to the generator controller.

23. The generator assembly of claim 21, wherein the generator controller comprises a first, inner control loop to control the excitation coil current and a second, outer control loop to control the rectified generator output voltage to a rectified generator output voltage setpoint, and wherein the first control loop comprises:

a first current measuring circuit configured to measure the excitation coil current as input to a first signal conditioner to generate a first feedback signal to be subtracted from the excitation coil current setpoint as input to a current controller to generate a PWM control signal as input to a PWM generator to generate a driver control signal as input to a driver circuit coupled to the first and/or second active switching circuit to control the duty cycle of the first and/or second active switching circuit.

24. A method for operating a generator including controlling a current through an excitation coil of the generator comprising:

switching a first terminal of an excitation coil either to a first or to a second terminal of a voltage source;

switching a second terminal of the excitation coil either to the first or to the second terminal of the voltage source; and

controlling the duty cycle of the switching to track an excitation coil current setpoint.

25. A method for operating a generator including reducing variations of an output voltage of the generator due to variations of a load of the generator comprising:

reversing a voltage across an excitation coil of the generator during at least one predetermined period of time; and

controlling the duration of the at least one predetermined period of time to track an excitation coil current setpoint.