UPS FREQUENCY CONVERTER AND LINE CONDITIONER

• US 20090237963A1
• Filed: 03/24/2008
• Published: 09/24/2009
• Est. Priority Date: 03/24/2008
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Klikic, Damir, Prasad, Pyboyina, Ghosh, Rajesh
• Granted Patent: US 7,881,079 B2
• Time in Patent Office: Days
• US Class Current: 363/40
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Systems and methods disclosed herein monitor and control input to a converter in one or more of a UPS, a frequency converter, or a line conditioner. Distortion due at least in part to ripple voltage can be removed from a control signal that controls input current to the converter. The systems and methods described herein afford a simple and effective way to reduce or eliminate one or more of subharmonic oscillation and total harmonic distortion from a converter input current during synchronous and asynchronous modes of operation. The converter may include one or more of a rectifier and an inverter.

Claims

1. A method for controlling a converter, comprising:

receiving a voltage signal including a ripple voltage;

determining a control signal based in part on the voltage signal by comparing the voltage signal with a reference signal, the control signal including distortion associated with the ripple voltage;

producing an average control signal by filtering at least a portion of the ripple voltage from the control signal;

generating a reference current value based at least in part on the average control signal; and

driving an input current of the converter toward the reference current value.

2. The method of claim 1, wherein driving an input current includes providing power factor correction for the input current of the converter.

3. The method of claim 1, comprising:

shifting a phase of the average control signal.

4. The method of claim 1, comprising:

providing an output current from the converter to a load, wherein the output current has a frequency that is synchronous with a frequency of the input current.

5. The method of claim 1, comprising:

providing an output current from the converter to a load, wherein the output current has a frequency that is asynchronous with a frequency of the input current.

6. The method of claim 1, comprising:

filtering the ripple voltage from the voltage signal; and

driving the voltage signal toward a reference voltage value.

7. The method of claim 6, comprising:

applying the voltage signal to an inverter associated with the converter.

8. The method of claim 1, wherein generating the reference current value comprises:

receiving a root mean squared input signal from the converter.

9. The method of claim 1, wherein driving the input current comprises:

adjusting a duty cycle of a pulse width modulation control signal associated with the input current.

10. The method of claim 1, wherein the ripple voltage includes a rectifier ripple voltage and an inverter ripple voltage.

11. The method of claim 1, comprising:

controlling the converter to operate in one of a synchronous mode of operation and an asynchronous mode of operation.

12. The method of claim 1, wherein the converter comprises at least one of an uninterruptable power supply, a frequency converter, and a line conditioner.

13. The method of claim 1, wherein producing the average control signal comprises:

sampling the control signal at a plurality of time instances of a time period of the voltage signal.

14. The method of claim 1, wherein receiving the voltage signal, determining the control signal, producing the average control signal, generating the reference current value, and driving the input current of the converter toward the reference current value are performed at least in part by a processor, and wherein the method is implemented at least in part by a program stored in a computer readable medium and executed by the processor.

15. A converter, comprising:

an input configured to receive input current;

an output configured to provide output current;

a control module including a filter;

the filter adapted to receive a control signal having distortion associated with a ripple voltage and to produce an average control signal substantially free of the ripple voltage;

the control module adapted to generate a reference current value based at least in part on the average control signal; and

the control module adapted to drive the input current of the converter toward the reference current value.

16. The converter of claim 15, comprising:

a rectifier adapted to receive the input current.

17. The converter of claim 16, comprising:

an inverter associated with the rectifier wherein the input current is in phase with an inverter output current.

18. The converter of claim 16, comprising:

an inverter; and

the filter adapted to remove at least part of a subharmonic oscillation signal from the input current.

19. The converter of claim 16, wherein the ripple voltage includes at least one of a rectifier ripple voltage and an inverter ripple voltage.

20. The converter of claim 16, comprising:

a lead-lag compensator adapted to adjust a phase of the average control signal.

21. The converter of claim 16, comprising:

the rectifier associated with an inverter; and

the filter adapted to remove at least a portion of harmonic distortion from the input current.

22. The converter of claim 21, wherein harmonic distortion is less than or equal to 3.5% of the input current.

23. The converter of claim 16, wherein the control module is adapted to adjust the control signal to drive a rectifier voltage toward a reference voltage value.

24. The converter of claim 23, wherein the control module is adapted to generate the reference current value based at least on part on a root mean squared value of the rectifier voltage.

25. The converter of claim 15, wherein the filter is adapted to remove at least a portion of harmonic distortion from the input current.

26. The converter of claim 15, comprising:

a control signal generator associated with the control module, the control signal generator adapted to adjust a duty cycle of a pulse width modulation control signal to drive the input current of the converter toward the reference current value.

27. The converter of claim 15, comprising at least one of an AC-DC pulse width modulation converter having a rectifier, and an AC-DC-AC pulse width modulation converter having the rectifier and an inverter.

28. The converter of claim 15, comprising at least one of an uninterruptable power supply, a frequency converter, and a line conditioner.

29. The converter of claim 15, comprising:

a converter output current having a frequency of between 55 Hz and 65 Hz.

30. The converter of claim 29, wherein the input current includes a frequency of between 45 Hz and 55 Hz.

31. A system for controlling an uninterruptable power supply, comprising:

means for filtering a control signal having distortion associated with a ripple voltage to produce an average control signal substantially free of distortion;

a control module associated with the uninterruptable power supply and adapted to generate a reference current value based at least in part on the average control signal; and

the control module adapted to drive an input current of the uninterruptable power supply toward the reference current value.

32. The system of claim 31, wherein the uninterruptable power supply includes at least one of a frequency converter and a line conditioner.

33. A computer readable medium having stored thereon sequences of instructions including instructions that will cause a processor to control a converter to:

receive information related to a voltage signal including a ripple voltage;

produce an average control signal by filtering at least a portion of the ripple voltage from a control signal;

determine the control signal based in part on the voltage signal by comparing the voltage signal with a reference signal, the control signal including distortion associated with the ripple voltage;

generate a reference current value based at least in part on the average control signal;

drive an input current of the converter toward the reference current value; and

apply the input current to a rectifier associated with at least one of an uninterruptable power supply, a frequency converter, and a line conditioner.