Device for distributed maximum power tracking for solar arrays

• US 8,093,757 B2
• Filed: 11/23/2010
• Issued: 01/10/2012
• Est. Priority Date: 07/13/2004
• Status: Active Grant

• Current Assignee: Tigo Energy, Inc
• Original Assignee: Tigo Energy, Inc
• Inventors: Wolfs, Peter
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US12/953,337
• Publication Number:
  US 20110062784A1
• Time in Patent Office: 413 Days
• Field of Search: 323/299, 323/284, 323/906, 323/285, 307/75, 307/84
• US Class Current: 307/75
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: G05F 5/00 Systems for regulating electric variables by detecting deviations in the electric input to the system and thereby controlling a device within the system to obtain a regulated output
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 323/906 Solar cell systems

Abstract

The present invention is a system for providing power from solar cells whereby each cell or cell array is allowed to produce its maximum available power and converted by an operatively connected DC/DC converter. Each cell or cell array has its own DC/DC converter. In one form the system for providing power from solar cells includes one or more solar generators wherein each of said solar generators has one to nine solar cells; a maximum power tracker operatively associated with each solar generator, each of said maximum power tracker includes a buck type DC/DC converter without an output inductor, each of said maximum power trackers are operatively connected in series with each other; an inductor operatively connected to the series connected maximum power trackers; and means for providing electrical power from the inductor to load means, wherein each of said maximum power trackers is controlled so that the operatively associated solar generator operates at its maximum power point to extract maximum available power.

Claims

1. A system for providing electrical power from solar cells, the system comprising:

a plurality of solar units, each of the solar units having only one pair of output connections to provide output, each of the solar units comprising;

a solar generator having at least one solar cell, and

a DC/DC converter coupled to the solar generator to receive electricity provided by the solar generator in entirety, wherein the DC/DC converter is controlled to operate the solar generator at a maximum power point;

wherein the output connections of the plurality of solar units are connected in series.

2. The system of claim 1, wherein the DC/DC converter has a switch and an energy storage capacitor coupled between the solar generator and the switch.

3. The system of claim 1, wherein the DC/DC converter is a buck-type converter without an output inductor.

4. The system of claim 1, wherein switching operations of DC/DC converters of the solar units are synchronized in frequency via a synchronizing signal.

5. A system, comprising:

a plurality of solar units, each of the solar units comprising

a solar generator having at least one solar cell to generate electrical power, and

a maximum power tracker coupled with the solar generator to operate the solar generator at a maximum power point, the maximum power tracker having a DC/DC converter without an output inductor, wherein all outputs of the maximum power trackers are connected to each other in series;

an inductor coupled with the plurality of solar units in series to provide the electrical power to a load.

6. The system of claim 5, wherein the maximum power tracker has an energy storage capacitor and a controller to adjust the duty cycle of the DC/DC converter to operate the solar generator at the maximum power point.

7. The system of claim 6, wherein the controller is to adjust a duty cycle of the DC/DC converter to extract maximum power from the solar generator based on a voltage of the solar generator, a voltage of the energy storage capacitor, and a duration of switch off time of the DC/DC converter.

8. The system of claim 5, wherein the DC/DC converter comprises a step down converter.

9. The system of claim 8, wherein the inductor is a single inductor shared by the step down converters of the solar units connected in series.

10. The system of claim 5, wherein the load includes devices that use or store the electrical power.

11. The system of claim 5, wherein switching operations of the DC/DC converters of the maximum power trackers are synchronized in frequency but have offsets in phase.

12. An apparatus, comprising:

a solar generator to generate electricity; and

a converter coupled between the solar generator and a series connection of solar generators, the converter having at least a first switch, the solar generator to generate a first current to provide electricity to the series connection of solar generators via the first switch of the converter, the converter to allow a second current larger than the first current to flow through the series connection of solar generators.

13. The apparatus of claim 12, wherein the solar generator is at least one solar cell of a solar panel;

and the converter has no inductor.

14. The apparatus of claim 12, wherein the converter is a buck-type converter without an output inductor.

15. The apparatus of claim 12, wherein the converter further comprises an energy storage unit connected to the solar generator;

wherein, when the first switch is turned on, the solar generator provides the first current to the series connection of solar generators, the energy storage unit provides a third current, and the second current is equal to or larger than a sum of the first current and the third current; and

wherein, when the first switch is turned off, the solar generator and the energy storage unit are electronically disconnected from the series connection of solar generators, and the converter provides at least one path for the series connection of solar generators.

16. The apparatus of claim 15, wherein the energy storage unit comprises a capacitor coupled in parallel with the solar generator;

and when the first switch is turned on, an output voltage of the converter is substantially equal to an output voltage of the solar generator.

17. The apparatus of claim 16, wherein the at least one path includes at least one of:

a diode,

a second switch, wherein the converter turns off the second switch when the first switch is turned on, and

a synchronous rectifier.

18. The apparatus of claim 12, wherein the converter further comprises a controller to control the first switch according to a duty cycle.

19. The apparatus of claim 18, wherein the controller is to further control the first switch according to at least one of:

a phase shift, and a synchronizing signal.

20. The apparatus of claim 12, wherein the converter is a first converter and the solar generator is a first solar generator;

and the apparatus further comprises;

a second converter and a second solar generator, the second converter connected to the first converter in series, the second converter having at least a second switch, the second solar generator to provide electricity to the series connection of solar generators via the second switch of the second converter, the second converter to allow the second current, larger than a current from the second solar generator, to flow through the series connection of solar generators.