Enhanced Systems and Methods for Using a Power Converter for Balancing Modules in Single-String and Multi-String Configurations

• US 20120255591A1
• Filed: 11/04/2009
• Published: 10/11/2012
• Est. Priority Date: 03/25/2009
• Status: Active Grant

• Current Assignee: Tigo Energy, Inc
• Original Assignee: Tigo Energy, Inc
• Inventors: Arditi, Shmuel, Makhota, Maxym
• Granted Patent: US 9,401,439 B2
• 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: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• 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 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

Apparatuses and methods include a solar array having one or more string buses of series-connected solar modules. The current outputs from the solar modules on each string bus can be balanced along with the voltage output from the string buses. Local management units coupled between the solar modules and the string buses are configured to control the voltage output from each solar module. When the solar modules on each string are balanced, and when the string buses are balanced (or before the solar modules and string buses are balanced), an inverter or other device connected to the solar array can find the array'"'"'s maximum power point via a maximum power point tracking algorithm.

Claims

1. A solar array comprising:

one or more string buses of series-connected solar modules, wherein

each solar module produces a current; and

each string bus produces a voltage; and

a controller configured to;

balance currents produced by the solar modules in each string bus; and

balance voltages produced by the one or more string buses in the solar array.

2. The solar array of claim 1, further comprising local management units each coupled between at least one of the solar modules and one of the string buses.

3. The solar array of claim 2, wherein the local management units are configured to decrease voltages produced by the solar modules.

4. The solar array of claim 3, wherein the local management units are only coupled between weak solar modules and the string buses.

5. The solar array of claim 2, wherein the number of solar modules exceeds the number of local management units.

6. The solar array of claim 2, wherein the controller is part of one of the local management units.

7. The solar array of claim 1, wherein operation of the controller is based on historical current and voltage data.

8. The solar array of claim 1, wherein the controller is configured to:

decrease a voltage output from weak solar modules in each string bus; and

decrease the voltage output from all solar modules on each weak string bus.

14. The method of claim 8, further comprising identifying each string bus as a strong string bus or a weak string bus.

15. The method of claim 14, wherein the identifying comprises:

varying an impedance seen by the one or more string buses;

monitoring changes in the current produced by each string bus; and

comparing the changes in current.

16. The method of claim 14, wherein the second balancing includes causing the voltage produced by the one or more string buses to converge on an average voltage produced by weak string buses.

17. The method of claim 8, further comprising applying a maximum power point tracking algorithm to the solar array.

9. A computer-implemented method comprising:

balancing, via a computing device, currents produced by solar modules in each of one or more string buses of a solar array; and

balancing, via the computing device, voltages produced by the one or more string buses of the solar array.

10. The method of claim 9, wherein the solar modules are connected in series.

11. The method of claim 9, further comprising identifying each solar module of the solar modules as a strong solar module or a weak solar module.

12. The method of claim 11, wherein the identifying comprises:

varying an impedance seen by the one or more string buses;

monitoring changes in voltage produced by each solar module; and

comparing the changes in voltage.

13. The method of claim 11, wherein the first balancing includes causing the current produced by the solar modules to converge on an average current produced by strong solar modules.

18. A solar array comprising:

a string bus of series-connected solar modules, wherein each solar module produces a current; and

a controller configured to balance currents produced by the solar modules.

19. The solar array of claim 18, further comprising local management units each coupled between at least one of the solar modules and the string bus.

20. The solar array of 19, wherein the local management units control voltage outputs from the solar modules.