System and method for power conversion

• US 8,310,102 B2
• Filed: 03/30/2011
• Issued: 11/13/2012
• Est. Priority Date: 03/30/2011
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Raju, Ravisekhar Nadimpalli
• Primary Examiner(s): Barnie, Rexford N
• Assistant Examiner(s): Fauth, Justen
• Application Number:
  US13/075,224
• Publication Number:
  US 20110221195A1
• Time in Patent Office: 594 Days
• Field of Search: None
• US Class Current: 307/82
• 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 7/49 Combination of the output voltage waveforms of a plurality of converters
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

A multilevel inverter is provided. The multilevel inverter includes a plurality of bridges, each bridge configured to receive a respective portion of an input DC power and convert the respective portion to a respective converted AC power. The multilevel inverter also includes at least one bridge controller for operating at least one of the plurality of bridges in a square waveform mode. The multilevel inverter further includes a plurality of transformers, each transformer coupled to a respective bridge and configured to increase a voltage level of the respective portion of converted AC power. The plurality of transformers further includes secondary windings coupled in series with the other secondary windings to combine the respective increased voltage level portions of the converted AC power. The multilevel inverter also includes a grid converter configured to provide output power for a power grid.

Claims

1. A multilevel inverter comprising;

a plurality of bridges, each bridge configured to receive a respective portion of an input DC power and convert the respective portion of the input DC power to a respective portion of converted AC power;

at least one bridge controller for operating at least one of the plurality of bridges in a square waveform mode;

a plurality of transformers, each transformer coupled to one of the respective bridge and configured to increase a voltage level of the respective portion of converted AC power of the respective bridge, wherein each of the plurality of transformers comprises a primary winding coupled to the respective bridge and a secondary winding paired with the primary winding and coupled in series with the other secondary windings to combine the respective increased voltage level portions of the converted AC power;

a grid converter electrically coupled to the series connected secondary windings of the plurality of transformers and configured to provide output power for a power grid; and

a grid controller configured to control operation of the grid converter, wherein the grid converter comprises an AC to AC converter and the grid controller is configured for providing control signals to control the frequency of the output power.

2. The multilevel inverter of claim 1, wherein the bridge controller is configured to provide control signals to operate at least one of the bridges at least partially in a duty cycle mode and to operate at least some of the remaining bridges in square waveform modes.

3. The multilevel inverter of claim 1, wherein the bridge controller is configured to provide control signals to operate one of the bridges at least partially in a duty cycle mode and to operate the remaining bridges entirely in square waveform modes.

4. The multilevel inverter of claim 1, wherein the bridge controller is configured to provide control signals to operate all of the bridges entirely in square waveform modes.

5. The multilevel inverter of claim 1, wherein the grid converter comprises a plurality of diodes and a plurality of semiconductor switches.

6. The multilevel inverter of claim 1, wherein at least one of the plurality of transformers comprises a different turns ratio of the primary winding and the respective secondary winding than another of the plurality of transformers.

7. The multilevel inverter of claim 6, wherein the different turns ratio generates a multilevel net output voltage.

8. A multilevel inverter comprising;

a plurality of bridges, each bridge configured to receive a respective portion of an input DC power and convert the respective portion of the input DC power to a respective portion of converted AC power;

at least one bridge controller for operating at least one of the plurality of bridges in a square waveform mode;

a plurality of transformers, each transformer coupled to one of the respective bridge and configured to increase a voltage level of the respective portion of converted AC power of the respective bridge, wherein each of the plurality of transformers comprises a primary winding coupled to the respective bridge and a secondary winding paired with the primary winding and coupled in series with the other secondary windings to combine the respective increased voltage level portions of the converted AC power;

a grid converter electrically coupled to the series connected secondary windings of the plurality of transformers and configured to provide output power for a power grid; and

a grid controller configured to control operation of the grid converter, wherein the grid converter comprises an AC to DC converter and the grid controller is configured for providing control signals to enable power supply from the power grid to a power source through the multilevel inverter.

9. The multilevel inverter of claim 8, wherein the bridge controller is configured to provide control signals to operate at least one of the bridges at least partially in a duty cycle mode and to operate at least some of the remaining bridges in square waveform modes.

10. The multilevel inverter of claim 8, wherein the bridge controller is configured to provide control signals to operate one of the bridges at least partially in a duty cycle mode and to operate the remaining bridges entirely in square waveform modes.

11. The multilevel inverter of claim 8, wherein the bridge controller is configured to provide control signals to operate all of the bridges entirely in square waveform modes.

12. The multilevel inverter of claim 8, wherein the grid converter comprises a plurality of diodes.

13. The multilevel inverter of claim 8, wherein the grid converter comprises a plurality of diodes and a plurality of semiconductor switches.

14. The multilevel inverter of claim 8, wherein at least one of the plurality of transformers comprises a different turns ratio of the primary winding and the respective secondary winding than another of the plurality of transformers.

15. The multilevel inverter of claim 14, wherein the different turns ratio generates a multilevel net output voltage.