Enhanced systems and methods for using a power converter for balancing modules in single-string and multi-string configurations

• US 9,401,439 B2
• Filed: 11/04/2009
• Issued: 07/26/2016
• Est. Priority Date: 03/25/2009
• Status: Active Grant

• Current Assignee: Tigo Energy, Inc
• Original Assignee: Tigo Energy, Inc
• Inventors: Arditi, Shmuel, Makhota, Maxym
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US12/612,641
• Publication Number:
  US 20120255591A1
• Time in Patent Office: 2,456 Days
• Field of Search: 307/43, 307 51- 52, 307/63, 307 71- 72, 307/75, 307/82, 307/151
• US Class Current: 1/1
• 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:

a plurality of string buses connected in parallel in the solar array;

a plurality of solar modules, wherein

each respective solar module of the solar modules has a local management unit configured to provide, to one of the string buses, electrical power generated by the respective solar module, and

each respective string bus of the string buses connects in series electrical power provided by local management units of a subset of the solar modules in the respective string bus;

a controller configured to communicate with local management units of the solar modules to;

adjust current-voltage output characteristics of at least one solar module in the respective string bus to cause the at least one solar module to have a maximum module current output that matches with maximum module current outputs of the other solar modules in the respective string bus; and

adjust current-voltage output characteristics of at least one string bus to cause the at least one string bus to have a maximum string voltage output that matches with maximum string voltage outputs of the other string buses connected in parallel in the solar array; and

a maximum power point tracker coupled with the string buses to receive electrical power from the string buses in parallel, the maximum power point tracker configured to track a maximum power point of the plurality of string buses by varying a current passing through the maximum power point tracker at a time when the solar modules in the respective string bus are configured via the local management units to have the maximum module current output in current-voltage output characteristics and the string buses in the solar array are configured via the local management units to have the maximum string voltage output in current-voltage output characteristics.

2. The solar array of claim 1, wherein the controller is part of one of the local management units of the solar modules.

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

4. The solar array of claim 1, wherein the respective solar module of the solar modules provides, via the local management unit, the electrical power generated by the respective solar module solely to the respective string bus.

5. A method of operating a plurality of solar modules, the method comprising:

communicating, by a controller, with local management units of the plurality of solar modules in a plurality of string buses, the string buses connected in parallel in a solar array, wherein

each respective solar module of the solar modules has a local management unit configured to provide, to one of the plurality of string buses, electrical power generated by the respective solar module,

each respective string bus of the string buses connects in series electrical power provided by local management units of a subset of the solar modules in the respective string bus, and

a maximum power point tracker is coupled with the string buses to receive electrical power from the plurality of string buses in parallel, the maximum power point tracker configured to track a maximum power point of the plurality of string buses;

wherein the communicating includes;

communicating with the local management units of the solar modules to adjust current-voltage output characteristics of at least one solar module in the respective string bus to cause the at least one solar module to have a maximum module current output that matches with maximum module current outputs of the other solar modules in the respective string bus; and

communicating with the local management units of the solar modules to adjust current-voltage output characteristics of at least one string bus to cause the at least one string bus to have a maximum string voltage output that matches with maximum string voltage outputs of the other string buses connected in parallel in the solar array;

wherein the maximum power point tracker tracks the maximum power point of the plurality of string buses by varying a current passing through the maximum power point tracker at a time when the solar modules in the respective string bus are configured via the local management units to have the maximum module current output in current-voltage output characteristics and the string buses in the solar array are configured via the local management units to have the maximum string voltage output in current-voltage output characteristics.

6. The method of claim 5, further comprising applying by the maximum power point tracker, a maximum power point tracking algorithm to the plurality of string buses as a whole.

7. The method of claim 5, wherein the respective solar module of the solar modules provides, via the local management unit, the electrical power generated by the respective solar module solely to the respective string bus.

8. A method of operating a plurality of solar modules, the method comprising:

communicating, by a controller, with local management units of the plurality of solar modules connected in a string bus, wherein

each respective solar module of the solar modules has a local management unit configured to provide electrical power generated by the respective solar module to the string bus,

the string bus connects in series electrical power provided by local management units in the string bus, and

a maximum power point tracker is coupled with the string bus to receive electrical power from the string bus, the maximum power point tracker configured to track a maximum power point of a solar array including the string bus;

wherein the communicating includes;

communicating with the local management units of the solar modules to adjust current-voltage output characteristics of at least one of the solar modules in the string bus to cause the at least one solar module to have a maximum module current output that matches with maximum module current outputs of the other solar modules connected in the string bus;

wherein the maximum power point tracker tracks the maximum power point of a solar array including the string bus by varying a current passing through the maximum power point tracker at a time when the solar modules in the string bus are configured via the local management units to have the maximum module current output in current-voltage output characteristics.

9. The method of claim 8, wherein the respective solar module of the solar modules provide via the local management unit, the electrical power generated by the respective solar module solely to the string bus.

10. A solar array comprising:

a plurality of solar modules, each of the solar modules having a local management unit;

a string bus configured to receive electrical power generated by the solar modules via series-connected local management units of the solar modules; and

a controller configured to communicate with the local management units of the solar modules to balance currents produced by the solar modules via adjusting current-voltage output characteristics of at least one of the solar modules in the string bus to have a matching maximum module current output with the other solar modules connected in the string bus;

wherein each of the solar modules provides electrical energy only to the string bus via a corresponding one of the series-connected local management units.

11. The solar array of claim 10, wherein the local management units control voltage outputs from the solar modules.

12. A solar array system having a plurality of solar modules, the system comprising:

a plurality of string buses, each respective string bus of the plurality of string buses configured to receive electrical power from at least one solar module, wherein each respective solar module of the plurality of solar modules includes a local management unit configured to provide electrical power generated by the respective solar module to the respective string bus;

a maximum power point tracker coupled with the plurality of string buses to receive electrical power from the string buses in parallel; and

a controller configured to communicate with local management units of the solar modules to adjust current-voltage output characteristics of at least one of the string buses to have a matching maximum string voltage output with the other string buses in the plurality of string buses.

13. The solar array system of claim 12, wherein the respective solar module of the plurality of solar modules provides, via the local management unit, the electrical power generated by the respective solar module solely to the respective string bus.