SYSTEM AND METHOD FOR OVER-VOLTAGE PROTECTION OF A PHOTOVOLTAIC SYSTEM WITH DISTRIBUTED MAXIMUM POWER POINT TRACKING

• US 20100327659A1
• Filed: 04/16/2010
• Published: 12/30/2010
• Est. Priority Date: 04/17/2009
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Chemistruck, Andrew Ronald, Socci, Gerand, Lisi, Gianpaolo, Djabbari, Ali, Subramoniam, Rajaram, Mahmodieh, Kosha, Zhang, Jianhui
• Granted Patent: US 8,810,068 B2
• Time in Patent Office: Days
• US Class Current: 307/82
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• 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: 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: H02S 50/00 Monitoring or testing of PV systems, e.g. load balancing or fault identification
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A solar panel array for use in a solar cell power system is provided. The solar panel array includes a string of solar panels and multiple voltage converters. Each voltage converter is coupled to a corresponding solar panel in the string of solar panels. The solar panel array also includes multiple maximum power point tracking (MPPT) controllers. Each MPPT controller is coupled to a corresponding solar panel in the string of solar panels. Each MPPT controller is configured to sense an instantaneous power unbalance between the corresponding solar panel and an inverter.

Claims

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

a string of solar panels;

multiple voltage converters, each voltage converter coupled to a corresponding solar panel in the string of solar panels; and

multiple maximum power point tracking (MPPT) controllers, each MPPT controller coupled to a corresponding solar panel in the string of solar panels, each MPPT controller configured to sense an instantaneous power unbalance between the corresponding solar panel and an inverter.

2. The solar panel array as set forth in claim 1, wherein at least one of the MPPT controllers is configured to limit a duty cycle of at least one of the voltage converters.

3. The solar panel array as set forth in claim 2, wherein at least of the MPPT controllers is configured to limit a conversion ratio of at least one of the voltage converters to a specified value.

4. The solar panel array as set forth in claim 2, wherein at least one of the MPPT controllers is configured to reduce the duty cycle to a fixed quantity.

5. The solar panel array as set forth in claim 2, wherein at least one of the MPPT controls is configured to reduce the duty cycle by an amount proportional to an output value.

6. The solar panel array as set forth in claim 1, wherein at least one of the MPPT controllers is configured to regulate a voltage of at least one of the voltage converters if an output current of the at least one voltage converter is less than a threshold current.

7. The solar panel array as set forth in claim 1, wherein at least one of the MPPT controllers is configured to estimate at least one variable based on a sensed value.

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

a voltage converter adapted to be coupled to a solar panel in a string of solar panels; and

a maximum power point tracking (MPPT) controller coupled to the voltage converter, the MPPT controller configured to sense an instantaneous power unbalance between the solar panel and an inverter.

9. The device as set forth in claim 8, wherein the MPPT controller is configured to limit a duty cycle of the voltage converter.

10. The device as set forth in claim 9, wherein the MPPT controller is configured to limit a conversion ratio of the voltage converter to a specified value.

11. The device as set forth in claim 9, wherein the MPPT controller is configured to reduce the duty cycle of the voltage converter to a fixed quantity.

12. The device as set forth in claim 9, wherein the MPPT control is configured to reduce the duty cycle of the voltage converter by an amount proportional to an output value.

13. The device as set forth in claim 8, wherein the MPPT controller is configured to regulate a conversion ratio of the voltage converter if an output current of the voltage converter is less than a threshold current.

14. The device as set forth in claim 8, wherein the MPPT controller is configured to estimate at least one variable based on a sensed value.

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

sensing at least one of multiple power variables;

detecting a power unbalance between a solar panel in a string of solar panels and an inverter coupled to a solar panel array;

regulating an output of a voltage converter.

16. The method set forth in claim 15, wherein regulating the output of the voltage converter comprises limiting a duty cycle of the voltage converter.

17. The method as set forth in claim 16, wherein limiting the duty cycle of the voltage converter comprises limiting a conversion ratio of the voltage converter to a specified value.

18. The method as set forth in claim 16, wherein the duty cycle of the voltage converter comprises at least one of:

reducing the duty cycle to a fixed quantity, reducing the duty cycle by an amount proportional to an output voltage, and reducing the duty cycle by an amount proportional to the output voltage slew-rate.

19. The method as set forth in claim 16, further comprising:

regulating a conversion ratio of the voltage converter if an output current of the voltage converter is less than a threshold current.

20. The method as set forth in claim 15, further comprising:

estimating at least one power variable based on a sensed value.