Power converting apparatus, control method therefor, and power generation system

• US 6,678,174 B2
• Filed: 11/27/2001
• Issued: 01/13/2004
• Est. Priority Date: 11/27/2000
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Suzui, Masaki, Takehara, Nobuyoshi, Manabe, Naoki, Kurokami, Seiji
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US09/993,655
• Publication Number:
  US 20020085397A1
• Time in Patent Office: 777 Days
• Field of Search: 363/34, 363/35, 363/37, 363/55, 363/56.1, 363/56.05, 363/56.12
• US Class Current: 363/55
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

In a solar power generation system having an inverter, if a smoothing capacitor in the inverter degrades, the operation of the inverter is interrupted, and a loss in the amount of power generation occurs inevitably. To prevent this loss, a degradation determination section (211) and output suppressing section (212) are provided in an inverter (2). If the degradation determination section (211) determines a degradation in capacitor (24), the operation of the inverter (2) is continued while suppressing the output current of the inverter (2) by the output suppressing section (212). In addition, a warning section (213) warns the user about the degradation in capacitor (24). With this arrangement, a solar power generation system capable of detecting a degradation in smoothing capacitor in the inverter (2) and appropriately operating the inverter (2) can be provided.

Claims

1. A power converting apparatus having a capacitor, comprising:

a degradation determination section arranged to determine a degradation in the capacitor; and

an output suppressing section arranged to, while said degradation determination section determines the degradation in the capacitor, repeat a decrease of a maximum output value from the power converting apparatus in units of predetermined suppression amounts.

2. The apparatus according to claim 1, wherein said output suppressing section repeats the decrease of the maximum output value in units of predetermined suppression amounts until the maximum output value becomes not more than a predetermined value.

3. The apparatus according to claim 2, wherein when a sum of suppression amounts of the maximum output value exceeds a predetermined value, said output suppressing section stops output of the power converting apparatus.

4. The apparatus according to claim 3, wherein when a sum of suppression amounts of the maximum output value exceeds a predetermined ratio of the maximum output value before suppression, said output suppressing section stops output of the power converting apparatus.

5. The apparatus according to claim 4, wherein the predetermined ratio is 30%.

6. The apparatus according to claim 2, wherein the unit of the suppression amount is 1% of the maximum output value before suppression.

7. The apparatus according to claim 1, wherein the capacitor comprises a smoothing capacitor arranged at an input section of the power converting apparatus.

8. The apparatus according to claim 7, wherein said degradation determination section determines the degradation on the basis of a ripple component of a voltage across terminals of the capacitor.

9. The apparatus according to claim 7, wherein said degradation determination section determines the degradation on the basis of a ripple component of a DC current of the capacitor.

10. The apparatus according to claim 7, wherein said degradation determination section determines the degradation on the basis of an increase in temperature of the capacitor.

11. The apparatus according to claim 1, further comprising warning section arranged to warn a user about the degradation in capacitor when said degradation determination section determines the degradation in the capacitor.

12. The apparatus according to claim 3, further comprising warning section arranged to warn a user about the degradation in the capacitor when said degradation determination section determines the degradation in capacitor, and warning that a service life of the capacitor is going to expire when the sum of the suppression amounts in said output suppressing means exceeds the predetermined value.

13. A power generation system comprising a DC power supply, a power converting apparatus for converting DC power output from said DC power supply into AC power, and a load operated by the AC power, wherein the power converting apparatus comprises the power converting apparatus of claim 1.

14. The system according to claim 13, wherein said DC power supply comprises a solar battery.

15. A control method for a power converting apparatus having a capacitor, comprising:

a degradation determination step of determining a degradation in the capacitor; and

an output suppressing step of, while the degradation in the capacitor is determined in the degradation determination step, repeating a decrease of a maximum output value from the power converting apparatus in units of predetermined suppression amounts.

16. The method according to claim 15, wherein in the output suppressing step, the decrease of the maximum output value is repeated in units of predetermined suppression amounts until the maximum output value becomes not more than a predetermined value.

17. The method according to claim 16, wherein in the output suppressing step, when a sum of suppression amounts of the maximum output value exceeds a predetermined value, output of the power converting apparatus is stopped.

18. A program which is executed by a computer to realize the power converting apparatus control method of claim 15.

19. A recording medium which stores the program of claim 18.