Maximized power in a photovoltaic distributed power system

• US 9,853,565 B2
• Filed: 05/09/2016
• Issued: 12/26/2017
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Yoscovich, Ilan, Bieber, Ofir, Glovinsky, Tzachi
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): Ly, Xuan
• Application Number:
  US15/149,353
• Publication Number:
  US 20160254672A1
• Time in Patent Office: 596 Days
• Field of Search: 307 45
• 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 3/38 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 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02M 3/04 by static converters
• CPC Class Codes: H02M 7/44 by static converters
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A power harvesting system including multiple parallel-connected photovoltaic strings, each photovoltaic string includes a series-connection of photovoltaic panels. Multiple voltage-compensation circuits may be connected in series respectively with the photovoltaic strings. The voltage-compensation circuits may be configured to provide respective compensation voltages to the photovoltaic strings to maximize power harvested from the photovoltaic strings. The voltage-compensation circuits may be include respective inputs which may be connected to a source of power and respective outputs which may be connected in series with the photovoltaic strings.

Claims

1. A method comprising:

coupling inputs of a power converter across a string of photovoltaic modules;

directly connecting a first input of the inputs of the power converter to an output of the power converter via a direct bypass link; and

dividing a current output by the string of photovoltaic modules into;

a first current that flows from the first input of the power converter to the output of the power converter via the power converter, and

a second current that flows directly from the first input of the power converter to the output of the power converter via the direct bypass link,

wherein the second current is greater than the first current.

2. The method of claim 1, further comprising configuring the power converter to draw power output by the string of photovoltaic modules and to output a voltage to control an operating point of the string of photovoltaic modules.

3. The method of claim 1, wherein coupling inputs of the power converter comprises coupling inputs of a DC/DC power converter that comprises inputs and outputs, wherein the inputs of the DC/DC power converter are electrically isolated from the outputs of the DC/DC power converter.

4. The method of claim 1, wherein the power converter is configured to adjust a polarity of a voltage output from the power converter.

11. The method of claim 1, further comprising:

adding to or subtracting from a voltage of the string of photovoltaic modules by switching a polarity of the output of the power converter.

5. A system comprising:

a plurality of parallel-connected photovoltaic strings, a first photovoltaic string of the plurality of parallel-connected photovoltaic strings comprising;

a series-connection of photovoltaic cells; and

a voltage-compensation circuit comprising output terminals and input terminals, the output terminals connected in series with the series-connection of photovoltaic cells, and the input terminals connected across the first photovoltaic string, wherein the voltage-compensation circuit is configured to output an adjustable compensation voltage, and wherein a first current from the first photovoltaic string flows from a first input terminal of the of the voltage-compensation circuit to a first output terminal of the of the voltage-compensation circuit via the voltage-compensation circuit; and

a direct bypass link directly connecting the first input terminal of the voltage-compensation circuit and the first output terminal of the voltage-compensation circuit, wherein a second current from the first photovoltaic string flows from the first input terminal of the voltage-compensation circuit to the first output terminal of the voltage-compensation circuit via the direct bypass link, the second current greater than the first current.

6. The system of claim 5, wherein the voltage-compensation circuit is configured to convert the first

current into the adjustable compensation voltage at the output terminals.

7. The system of claim 5, wherein the input terminals are connected across a source of power separate from a power provided by the system.

8. The system of claim 6, further comprising a power device connected to the plurality of parallel-connected photovoltaic strings, wherein the power device is configured to determine an optimal power level, and wherein each of the plurality of parallel-connected photovoltaic strings is configurable to supply power at different levels based on the optimal power level.

9. The system of claim 6, wherein the voltage compensation circuit is configured add the adjustable compensation voltage to or subtract the adjustable compensation voltage from a voltage of the first photovoltaic string connected to the voltage compensation circuit.

10. The system of claim 8, wherein the voltage-compensation circuit is configured to adjust the adjustable compensation voltage based on the optimal power level.

12. The system of claim 10, the plurality of parallel-connected photovoltaic strings comprising a second photovoltaic string, the second photovoltaic string comprising:

a second series-connection of photovoltaic cells; and

a second voltage-compensation circuit comprising second output terminals and second input terminals and configured to output a second adjustable compensation voltage, the second output terminals connected in series with the second series-connection of photovoltaic cells, and the second input terminals connected across the second photovoltaic string.

13. The system of claim 12, wherein the second voltage-compensation circuit is configured to adjust the second adjustable compensation voltage based on the optimal power level.

14. The system of claim 13, wherein the adjustable compensation voltage is at a different level from the second adjustable compensation voltage.

15. A system comprising:

a photovoltaic string comprising;

a series-connection of photovoltaic cells;

a power device comprising output terminals and input terminals and configured to regulate a voltage drawn from the photovoltaic string, the output terminals connected to the series-connection of photovoltaic cells, and the input terminals connected across the photovoltaic string, wherein the power device is configured to direct a first current flow from a first input terminal of the input terminals to a first output terminal of the output terminals via the power device; and

a direct bypass link directly connecting the first input terminal and the first output terminal, wherein the power device is configured to direct a second current flow from the first input terminal to the first output terminal via the direct bypass link, the second current flow being greater than the first current flow.

16. The system of claim 15, further comprising:

a second photovoltaic string connected in parallel with the photovoltaic string, the second photovoltaic string comprising;

a second series-connection of photovoltaic cells;

a second power device comprising second output terminals and second input terminals and configured to regulate a second voltage drawn from the second photovoltaic string, the second output terminals connected to the second series-connection of photovoltaic cells, and the second input terminals connected across the second photovoltaic string, wherein the second power device is configured to direct a third current flow from a second input terminal of the second input terminals to a second output terminal of the second output terminals via the second power device; and

a second direct bypass link directly connecting the second input terminal and the second output terminal, wherein the second power device is configured to direct a fourth current flow from the second input terminal to the second output terminal via the second direct bypass link, the fourth current flow being greater than the third current flow.

17. The system of claim 16, further comprising:

a system power device connected to the power device and the second power device.

18. The system of claim 17, the system power device comprising an inverter configured to convert a DC input to an AC output.

19. The system of claim 17, the power device comprising a polarity adjustment circuit configured to convert a DC input to an AC output.

20. The system of claim 16, the power device comprising:

a converter configured to convert power received at the input terminals to an output DC voltage; and

a polarity adjustment circuit connected between the converter and the output terminals, the polarity adjustment circuit configured to adjust a polarity of the output DC voltage.