System and method for over-Voltage protection of a photovoltaic string with distributed maximum power point tracking

• US 20100288327A1
• Filed: 05/13/2009
• Published: 11/18/2010
• Est. Priority Date: 05/13/2009
• Status: Abandoned Application

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Lisi, Gianpaolo, Djabbari, Ali, Zhang, Jianhui
• Application Number:
  US12/454,136
• Publication Number:
  US 20100288327A1
• Time in Patent Office: Days
• US Class Current: 136/244
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02H 7/1222 responsive to abnormalities in the input circuit, e.g. transients in the DC input
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A string over-voltage protection system and method for arrays of photovoltaic panels. The system and method includes a device for use in a photovoltaic array power system. The device includes a voltage converter. The voltage converter is adapted to be coupled to a photovoltaic panel in a string of photovoltaic panels. The device also includes a string over-voltage protection circuit. The string over-voltage protection circuit is coupled to the voltage converter. The string over-voltage protection circuit senses a string voltage and determines if a string over-voltage condition exists. Additionally, the string over-voltage protection circuit is configured to disable the voltage converter in the event of a string over-voltage condition.

Claims

1. A solar panel array for use in a solar cell power system, the solar panel array comprising:

a number of strings of solar panels;

a number of voltage converters, wherein each of the voltage converters is coupled to a corresponding solar panel in the string of solar panels; and

a number of over-voltage protection circuits, wherein each of the over-voltage protection circuits is coupled to a corresponding voltage converter, each of the over-voltage protection circuits configured to control an operation of the voltage converter in response to a string over-voltage condition.

2. The solar panel array as set forth in claim 1, wherein each of the number of over-voltage protection circuits is configured to sense a voltage corresponding to a string voltage.

3. The solar panel array as set forth in claim 2, the voltage corresponding to the string voltage is a voltage between a positive output terminal and a housing of the voltage converter.

4. The solar panel array as set forth in claim 2, the voltage corresponding to the string voltage is a voltage between a positive output terminal of a first voltage converter and a negative output terminal of a second voltage converter.

5. The solar panel array as set forth in claim 1, wherein each of the number of over-voltage protection circuits includes at least one of a static threshold voltage value and dynamic threshold voltage value.

6. The solar panel array as set forth in claim 5, wherein at least one of the number of over-voltage protection circuits disables the voltage converter when a string voltage exceeds the threshold voltage.

7. The solar panel array as set forth in claim 1, wherein at least one of the number of over-voltage protection circuits controls operation of the voltage converter by at least one of:

switching OFF elements in the voltage converter;

limiting the output voltage of the voltage converter to a predetermined or calculated value; and

bypassing circuitry within the voltage converter.

8. A device for use in a solar cell power system, the device comprising:

a voltage converter, wherein the voltage converter is adapted to be coupled to a solar panel in a string of solar panels; and

an over-voltage protection circuit coupled to the voltage converter, the over-voltage protection circuit configured to control an operation of the voltage converter in response to a string over-voltage condition.

9. The device as set forth in claim 8, wherein the over-voltage protection circuit is configured to sense a voltage corresponding to a string voltage.

10. The device as set forth in claim 9, the voltage corresponding to the string voltage is a voltage between a positive output terminal and a housing of the voltage converter.

11. The device as set forth in claim 9, the voltage corresponding to the string voltage is a voltage between a positive output terminal of a first voltage converter and a negative output terminal of a second voltage converter.

12. The device as set forth in claim 8, wherein the over-voltage protection circuit includes at least one of a static threshold voltage value and dynamic threshold voltage value.

13. The device as set forth in claim 12, wherein the over-voltage protection circuit disables the voltage converter when a string voltage exceeds the threshold voltage.

14. The device as set forth in claim 8, wherein the over-voltage protection circuit controls operation of the voltage converter by at least one of:

switching OFF elements in the voltage converter;

limiting the output voltage of the voltage converter to a predetermined or calculated value; and

bypassing circuitry within the voltage converter.

15. A method for over-voltage protection in a photovoltaic array, the method comprising:

sensing a string voltage at a solar panel in a string of solar panels;

determining if the string voltage exceeds a threshold voltage; and

controlling and operation of a voltage converter coupled to the solar panel.

16. The method set forth in claim 15, wherein controlling disabling the voltage converter when the string voltage exceeds the threshold voltage.

17. The method as set forth in claim 16, wherein disabling further comprises at least one of:

switching OFF elements in the voltage converter;

limiting the voltage of the voltage converter to a predetermined or calculated value; and

bypassing circuitry within the voltage converter.

18. The method as set forth in claim 15, further comprising storing the threshold value in a memory.

19. The method as set forth in claim 15, wherein sensing further comprises sensing a voltage between a positive output terminal of the voltage converter and a housing of the voltage converter.

20. The method as set forth in claim 15, wherein sensing further comprises sensing a voltage between a positive output terminal of the voltage converter and a negative output terminal of a last voltage converter coupled to a last solar panel in the string of solar panels.