DC-TO-AC POWER CONVERSION SYSTEM AND METHOD

• US 20100141041A1
• Filed: 05/29/2009
• Published: 06/10/2010
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: GE Grid Solutions LLC (GE Aerospace)
• Original Assignee: General Electric Company
• Inventors: Bose, Sumit, Teichmann, Ralph, O'Brien, Kathleen Ann
• Granted Patent: US 8,427,010 B2
• Time in Patent Office: Days
• US Class Current: 307/82
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• 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

A system, in one embodiment, includes a photovoltaic power converter. The photovoltaic power converter includes one or more photovoltaic arrays configured convert solar energy into a DC signal and two or more N-level converters coupled to a common DC bus (N being an integer greater than 2).

Claims

1. A system comprising:

a photovoltaic power converter comprising;

one or more photovoltaic arrays configured convert solar energy into a DC signal; and

two or more N-level converters coupled to a common DC bus, wherein N is an integer greater than 2.

2. The system of claim 1, wherein the photovoltaic power converter comprises a single stage power converter, wherein the two or more N-level converters comprise:

a first DC-to-AC N-level converter; and

a second DC-to-AC N-level converter;

wherein the first and second DC-to-AC N-level converters are each configured to receive the DC signal via the common DC bus and to convert the DC signal into an AC signal, and wherein the first DC-to-AC N-level converter and the second DC-to-AC N-level converter are coupled to the common DC bus in parallel.

3. The system of claim 2, comprising a two-winding transformer coupled downstream from the two or more DC-to-AC N-level inverters.

4. The system of claim 3, wherein a first output of the first DC-to-AC N-level converter is coupled to a second output of the second DC-to-AC N-level converter at a common node, wherein the common node is coupled to a first winding of the two-winding transformer.

5. The system of claim 4, comprising a controller configured to phase-shift a first output of the first DC-to-AC N-level converter by 180 degrees relative to a second output of the second DC-to-AC N-level converter.

6. The system of claim 3, wherein a first output of the first DC-to-AC N-level converter and a second output of the second DC-to-AC N-level converter are each coupled to an open winding of the two-winding transformer.

7. The system of claim 1, wherein the photovoltaic power converter comprises a multi-stage power converter, wherein the two or more N-level converters comprise a DC-to-DC N-level converter and a DC-to-AC N-level converter;

wherein the DC-to-DC N-level converter is configured to step up the DC signal from the one or more photovoltaic arrays from a first DC voltage to a second DC voltage, and to transmit the second DC voltage to the DC-to-AC N-level converter via the common DC bus;

wherein the DC-to-AC N-level converter is configured to convert the second DC voltage into an AC signal.

8. The system of claim 7, comprising a first controller configured to control the DC-to-DC N-level converter and a second controller configured to control the DC-to-AC N-level converter.

9. The system of claim 7, wherein the two or more N-level converters comprises another DC-to-DC N-level converter coupled to the common DC bus and to an energy storage device, wherein the energy storage device is configured to store or output power depending at least partially upon the power demand of a load coupled to the DC-to-AC N-level converter.

10. The system of claim 8, wherein at least one of the first controller or the second controller comprises a maximum power point tracking (MPPT) control algorithm.

11. A system, comprising:

a photovoltaic power converter comprising;

two or more photovoltaic arrays coupled in series and configured to convert solar energy into a DC signal, wherein the two or more photovoltaic arrays comprise a first photovoltaic array and a second photovoltaic array;

a grounding point coupled between the first and second photovoltaic arrays; and

at least one N-level converter coupled downstream from the two or more photovoltaic arrays and configured to receive the DC signal on a DC bus, wherein N is an integer greater than 2.

12. The system of claim 11, wherein the grounding point is coupled to a negative side of the first photovoltaic array and a positive side of the second photovoltaic array.

13. The system of claim 11, wherein each of the first and second photovoltaic arrays are configured to provide a DC output signal corresponding to a first voltage level.

14. The system of claim 13, wherein a differential open-load voltage of the photovoltaic power converter is twice the first voltage level.

15. The system of claim 11, wherein the at least one N-level converter is configured to convert the DC signal into an AC signal.

16. The system of claim 11, wherein the at least one N-level converter comprises a neutral-point-clamped converter, a flying capacitor converter, a single-leg clamped converter, or a cascaded converters, or some combination thereof.

17. A system comprising:

a power converter comprising;

at least one DC power source configured to output a DC signal;

two or more N-level converters coupled to a common DC bus, wherein N is an integer greater than 2; and

a three-winding transformer coupled downstream from the two or more N-level converters.

18. The system of claim 17, wherein the two or more N-level converters comprise a first N-level converter and a second N-level converter, each being configured to receive the DC signal via the common DC bus and to convert the DC signal into an AC signal, and to output the AC signal via a respective output terminal.

19. The system of claim 18, wherein the three-winding transformer comprises:

a first primary winding coupled to the output terminal of the first N-level converter;

a second primary winding coupled to the output terminal of the second N-level converter; and

a secondary winding coupled to a power grid.

20. The system of claim 17, wherein the DC power source comprises a photovoltaic array, a fuel cell, or some combination thereof.