Health monitoring for power converter capacitors

• US 20090072982A1
• Filed: 09/14/2007
• Published: 03/19/2009
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Astec International Limited (Emerson Electric Company)
• Original Assignee: Astec International Limited (Emerson Electric Company)
• Inventors: Wang, Zhe, Wang, Lin Guo, Jiang, Huai Gang, Cheng, Wing Ling
• Granted Patent: US 7,830,269 B2
• Time in Patent Office: Days
• US Class Current: 340/635
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G01R 31/64 Testing of capacitors

Abstract

A method for detecting a performance degradation of a capacitor in a power converter is disclosed. The method includes monitoring a voltage across the capacitor, detecting the performance degradation of the capacitor based on the monitored voltage, and generating a warning signal after detecting the performance degradation of the capacitor. A power converter is including at least one capacitor and a processor operably coupled to the at least one capacitor for monitoring a voltage across the at least one capacitor is also disclosed. The processor is configured for detecting a performance degradation of the capacitor based, at least in part, on the monitored voltage, and for generating a warning signal after detecting the performance degradation of the at least one capacitor.

Claims

1. A method for detecting a performance degradation of a capacitor in a power converter, the method comprising:

monitoring a voltage across the capacitor;

detecting the performance degradation of the capacitor based on the monitored voltage; and

generating a warning signal after detecting the performance degradation of the capacitor.

2. The method of claim 1 wherein the capacitor is an electrolytic capacitor.

3. The method of claim 2 wherein the capacitor is a bulk capacitor.

4. The method of claim 2 wherein the capacitor is an output capacitor.

5. The method of claim 1 further comprising activating an alarm in response to the generated warning signal.

6. The method of claim 1 further comprising providing the generated warning signal to a system hosting the power converter.

7. The method of claim 1 wherein monitoring includes monitoring a ripple voltage across the capacitor.

8. The method of claim 7 wherein monitoring includes converting the ripple voltage to a PWM signal.

9. The method of claim 7 wherein monitoring includes converting the ripple voltage to an rms signal.

10. The method of claim 7 wherein detecting includes detecting when the monitored ripple voltage exceeds a predetermined value.

11. The method of claim 1 further comprising replacing the capacitor in response to the generated warning signal.

12. A power converter comprising at least one capacitor and a processor operably coupled to the at least one capacitor for monitoring a voltage across the at least one capacitor, the processor configured for detecting a performance degradation of the capacitor based, at least in part, on the monitored voltage, and for generating a warning signal after detecting the performance degradation of the at least one capacitor.

13. The power converter of claim 12 wherein the processor is configured for generating the warning signal when the detected performance degradation of the at least one capacitor exceeds a threshold level.

14. The power converter of claim 12 wherein the warning signal activates an alarm.

15. The power converter of claim 14 wherein the alarm is a visible alarm.

16. The power converter of claim 12 further comprising at least one LED, the processor configured for changing a state of the LED after detecting the performance degradation of the at least one capacitor.

17. The power converter of claim 12 wherein the at least one capacitor is an output capacitor.

18. The power converter of claim 17 wherein the monitored voltage is a ripple voltage.

19. The power converter of claim 18 further comprising a ripple sampling circuit operably connected between the output capacitor and the processor, the ripple sampling circuit operable to provide a signal representative of a magnitude of the ripple voltage to the processor.

20. The power converter of claim 19 further comprising a current sampling circuit operably connected between the processor and an output stage of the power converter, the current sampling circuit operable to provide a signal representative of an output current to the processor.

21. The power converter of claim 20 wherein the processor is configured for comparing the ripple voltage and output current signals with stored data to detect the performance degradation of the output capacitor.

22. The power converter of claim 19 wherein the signal representative of the magnitude of the ripple voltage is an RMS voltage.

23. The power converter of claim 12 wherein the at least one capacitor is a bulk capacitor.

24. The power converter of claim 23 wherein the monitored voltage is a ripple voltage.

25. The power converter of claim 24 further comprising a ripple sampling circuit operably connected between the bulk capacitor and the processor, the ripple sampling circuit operable to provide a signal representative of a magnitude of the ripple voltage to the processor.

26. The power converter of claim 25 wherein the signal provided by the ripple sampling circuit is a PWM signal.

27. The power converter of claim 25 further comprising a current sampling circuit operably connected between the processor and an output stage of the power converter, the current sampling circuit operable to provide a signal representative of an output current to the processor.

28. The power converter of claim 27 wherein the processor is configured for comparing the ripple voltage and output current signals with stored data to detect the performance degradation of the bulk capacitor.