Power system having a voltage regulator with a notch filter

• US 20070189045A1
• Filed: 02/13/2006
• Published: 08/16/2007
• Est. Priority Date: 02/13/2006
• Status: Active Grant

• Current Assignee: American Superconductor Corporation
• Original Assignee: American Superconductor Corporation
• Inventors: Gritter, David
• Granted Patent: US 7,778,053 B2
• Time in Patent Office: Days
• US Class Current: 363/40
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 7/53873 with digital control

Abstract

A control system for an AC line voltage distribution system includes a DC energy storage system and an inverter coupled to the DC energy storage system adapted for coupling to the AC line distribution system. A proportional-integral voltage regulator coupled to the DC energy storage system receives a voltage signal for the DC energy storage system and receives a voltage reference. In an exemplary embodiment, the voltage regulator includes a proportional path and an integral path to receive the DC voltage information and the voltage reference signal information, a filter to remove an AC component having a predetermined frequency contained in the DC voltage signal, and an output terminal to output a control signal with the AC component removed.

Claims

1. A voltage regulator device, comprising:

a first input terminal to receive a voltage signal for a DC bus and a second input terminal to receive a DC bus voltage reference signal;

a proportional path and an integral path to receive the DC bus voltage information and the voltage reference signal information;

a filter to remove an AC component having a predetermined frequency contained in the DC bus voltage signal; and

an output terminal to output a control signal with the AC component removed.

2. The device according to claim 1, wherein the filter is a notch filter tuned to about 120 Hz.

3. The device according to claim 2, wherein the notch filter is implemented as part of a phase locked loop.

4. The device according to claim 3, wherein a tuning parameter for the notch filter is derived from a frequency estimate of a phase locked loop locked to a positive sequence component of line voltage.

5. The device according to claim 1, wherein the notch filter includes a generalized integrator.

6. The device according to claim 1, further including a current regulator to receive the control signal.

7. The device according to claim 6, further including an inverter and a DC energy storage system coupled to the DC bus.

8. The device according to claim 7, further including a rectangular to polar converter and a space vector generator to generate gate signals to control the inverter.

9. A control system for an AC line voltage distribution system, comprising:

a DC energy storage system;

an inverter coupled to the DC energy storage system and adapted for coupling to the AC line distribution system;

a modulator to provide control signals to the inverter; and

a proportional-integral voltage regulator coupled to the DC energy storage system for receiving a voltage signal from the DC energy storage system and adapted for coupling to a voltage reference, the voltage regulator including;

a proportional path and an integral path to receive the DC voltage information and the voltage reference signal information;

a filter to remove an AC component having a predetermined frequency contained in the DC voltage signal; and

an output terminal to output a control signal with the AC component removed.

10. The system according to claim 9, wherein the filter is a notch filter tuned to about 120 Hz.

11. The system according to claim 9, wherein the notch filter is implemented as part of a phase locked loop.

12. The system according to claim 11, wherein a tuning parameter for the notch filter is derived from a frequency estimate of a phase locked loop locked to a positive sequence component of line voltage.

13. The system according to claim 9, wherein the notch filter includes a generalized integrator.

14. The system according to claim 9, further including a current regulator to receive the control signal.

15. A method, comprising:

receiving a voltage on a DC bus;

receiving a reference voltage;

processing the DC bus voltage and the reference voltage in a proportional path of a voltage regulator;

processing the DC bus voltage and the reference voltage in an integral path of the voltage regulator;

combining an output of the proportional path and an output of the integral path and removing an ac component having a certain frequency from the combined proportional path output and the integral path output; and

generating an output control signal with the ac component removed.

16. The method according to claim 15, further including removing the ac component with a notch filter in a phase locked loop.

17. The method according to claim 16, further including using a generalized integrator in the phase locked loop.

18. The method according to claim 15, further including providing the output control signal to a current regulator.

19. The method according to claim 15, further including using output control signal to generate gate signals for an inverter.

20. The method according to claim 19, further including using the inverter to enhance performance of an AC line distribution system.

21. The method according to claim 15, wherein the certain frequency of the ac component is about twice an estimated line frequency.

22. A regulator system, comprising:

a voltage regulator to receive a voltage signal from a DC bus and a DC bus reference signal and to output a control signal based upon the DC bus voltage signal and the DC bus reference signal;

a notch filter to receive the control signal and remove an AC component having a predetermined frequency contained in the DC bus voltage signal.

23. The system according to claim 22, wherein the notch filter is implemented as part of a phase locked loop.

24. The system according to claim 23, wherein a tuning parameter for the notch filter is derived from a frequency estimate of a phase locked loop locked to a positive sequence component of line voltage.

25. The system according to claim 22, wherein the AC component is due to an unbalanced line voltage in an AC line voltage distribution system.

26. The system according to claim 25, further including a current regulator to receive the filtered control signal and an inverter and a DC energy storage system coupled to the DC bus.