Current diversion for power-providing systems

Patent metadata

Field	Value
Publication number	US-9685789-B2
Application number	US-201414209882-A
Country	US
Kind code	B2
Filing date	Mar 13, 2014
Priority date	Mar 14, 2013
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

Various example embodiments are directed to methods and apparatuses for diverting current from a Photovoltaic (PV) module. In particular embodiments, the PV module can be part of a series connection (or string) of PV modules. The series connection provides a primary current path through which generated current flows. Current diversion circuit(s) can be used in connection with one or more PV modules. The current diversion circuit detects when the current through the primary current path is less than the desired current level for a corresponding PV module (e.g., the maximum power point). In response to this detection, the current diversion circuit can provide an alternate pathway for current from the corresponding PV module. This results in an overall increase in the current from the PV module and a corresponding increase in efficiency.

First claim

What is claimed is:

1. A photovoltaic power generation device comprising:
a plurality of photovoltaic modules configured and arranged in a series connection to provide a primary current path;
a secondary current path circuit;
an output circuit configured and arranged to receive power from the primary current path and the secondary current path circuit;
one or more current-diversion circuits configured and arranged to provide an adjustable amount of current from respectively corresponding ones of the plurality of photovoltaic modules to the secondary current path circuit; and
control logic, including circuitry, configured and arranged to adjust an amount of current provided by the current-diversion circuits in response to an algorithm that selectively controls current provided from the plurality of photovoltaic modules to the output circuit by limiting amounts of power lost through the one or more current diversion circuits, while diverting excess current potential that would otherwise remain unused by the plurality of photovoltaic modules, wherein the control logic is configured to selectively control current provided from the plurality of photovoltaic modules to the output circuit and therein avoid interference resulting from adjustments between multiple current-diversion circuits by coordinating different times for adjustments of different current-diversion circuits.

2. The device of claim 1 , wherein the algorithm favors providing current through the primary current path over current through the secondary current path circuit, and wherein the control logic is further configured and arranged to adjust the amount of current provided by the current-diversion circuits in response to the algorithm.

3. The device of claim 2 , wherein the algorithm is configured and arranged to adjust the amount of current provided by each of the one or more current-diversion circuits in a direction that increases a total amount of power provided by each of the plurality photovoltaic modules.

4. The device of claim 2 , wherein the algorithm is configured and arranged to determine, for each of the plurality photovoltaic modules, an amount of power that is provided through the primary current path and through the secondary current path circuit; to weight the amounts of power to favor more power being provided through the primary current path relative to power being provided through the secondary current path circuit; and to adjust the amount of current provided by the one or more current-diversion circuits in response to a figure of merit determined from the weighted amounts of power.

5. The device of claim 2 , wherein the control logic includes multiple circuits that are distributed across the one or more current-diversion circuits and wherein each of the multiple circuits is configured and arranged to apply the algorithm using inputs from a corresponding, local current-diversion circuit.

6. The device of claim 2 , wherein the algorithm is a greedy algorithm that is configured and arranged to operate independently for each of the one or more current-diversion circuits.

7. The device of claim 2 , wherein the algorithm is configured and arranged to perform a hill climbing routine using an amount of power provided by a corresponding and respective photovoltaic cell to calculate a figure of merit.

8. The device of claim 7 , wherein the algorithm is configured and arranged to avoid local maximums for the figure of merit by at least one of restarts of the hill climbing routine at different locations, changes to a step size for the hill climbing routine, and detecting that the figure of merit is below a calculated threshold value.

9. The device of claim 2 , wherein the control logic is configured and arranged to remove or bypass, in response to an overall current provided from the photovoltaic module being less than a threshold value, a selected photovoltaic module from the primary current path.

10. The device of claim 2 , wherein the algorithm is responsive to maximum power point tracking for the series connection of the plurality photovoltaic modules.

11. The device of claim 2 , wherein the algorithm further controls the amount of current provided by the current-diversion circuits in response to a desired voltage level across the series connection of the plurality photovoltaic modules.

12. The device of claim 1 , wherein the secondary current path circuit includes a voltage bus connected to both ends of the series connection of photovoltaic modules.

13. The device of claim 1 , wherein the one or more current-diversion circuits are DC-to-DC converters.

14. The device of claim 13 , wherein the one or more current-diversion circuits are configured and arranged to provide galvanic isolation between an input and output of the DC-to-DC converter.

15. The device of claim 1 , wherein the one or more current-diversion circuits are flyback converters.

16. The device of claim 1 , wherein the one or more current-diversion circuits are diagonal half-bridge flyback converters.

17. The device of claim 1 , further including a primary inverter circuit configured and arranged to convert power received from both the primary current path and the secondary current path circuit to alternating current (AC).

18. The device of claim 1 , further including additional photovoltaic modules configured and arranged in series to provide the primary current path, wherein the additional photovoltaic modules do not have corresponding and respective current-diversion circuits.

19. A photovoltaic power generation device comprising:
a plurality of photovoltaic modules configured and arranged in a series connection to provide a primary current path;
a secondary current path circuit;
an output circuit configured and arranged to receive power from the primary current path and the secondary current path circuit;
one or more current-diversion circuits configured and arranged to provide an adjustable amount of current from respectively corresponding ones of the plurality of photovoltaic modules to the secondary current path circuit; and
control logic, including circuitry, configured and arranged to adjust an amount of current provided by the current-diversion circuits in response to an algorithm that favors providing current through the primary current path over current through the secondary current path circuit, and configured and arranged to avoid interference resulting from adjustments between multiple current-diversion circuits by randomizing times at which adjustments are made to different current-diversion circuits.

20. A photovoltaic power generation device comprising:
a plurality of photovoltaic modules configured and arranged in a series connection to provide a primary current path;
a secondary current path circuit;
an output circuit configured and arranged to receive power from the primary current path and the secondary current path circuit;
one or more current-diversion circuits configured and arranged to provide an adjustable amount of current from respectively corresponding ones of the plurality of photovoltaic modules to the secondary current path circuit; and
control logic, including circuitry, configured and arranged to adjust an amount of current provided by the current-diversion circuits in response to an algorithm that favors providing current through the primary current path over current through the secondary current path circuit, and configured and arranged to avoid interference resulting from adjustments between multiple current-diversion circuits by coordinating

Assignees

• Univ Leland Stanford Junior

Inventors

• Dally William J
• Hau Darren
• Choksi Vivek
• Ponec Andrew J
• Ling Christopher

Classifications

• H02M3/3353

  having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter · CPC title

• H02J2101/25

  involving maximum power point tracking control for photovoltaic sources · CPC title

• H02J2101/24

  Photovoltaics · CPC title

• Y10T307/707

  Cross-Sectional Technologies · mapped topic

• Y10T307/691

  Cross-Sectional Technologies · mapped topic