Two-Terminal M2LC Subsystem and M2LC System Including Same

• US 20120068756A1
• Filed: 09/21/2011
• Published: 03/22/2012
• Est. Priority Date: 09/21/2010
• Status: Active Grant

• Current Assignee: Benshaw, Inc. (Regal Rexnord Corp.)
• Original Assignee: Curtiss-Wright Electro-Mechanical Corporation (Curtiss-Wright Corporation)
• Inventors: AIELLO, Marc Francis, Kramer, Dustin Matthew, Berton, Kenneth Stephen
• Granted Patent: US 8,649,187 B2
• Time in Patent Office: Days
• US Class Current: 327/333
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 1/0095 Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H02M 7/4837 Flying capacitor converters
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters

Abstract

A two-level two-terminal modular multilevel converter subsystem. The subsystem includes a first capacitor and a second capacitor. The modular multilevel converter subsystem is configured to selectively place the first capacitor in series with the second capacitor. The modular multilevel converter subsystem is also configured to selectively place the first capacitor in parallel with the second capacitor relative to first and second output terminals of the modular multilevel converter subsystem.

Claims

1. A two-level two-terminal modular multilevel converter subsystem, comprising:

a first capacitor; and

a second capacitor, wherein the modular multilevel converter subsystem is configured to;

selectively place the first capacitor in series with the second capacitor; and

selectively place the first capacitor in parallel with the second capacitor relative to first and second output terminals of the modular multilevel converter subsystem.

2. The modular multilevel converter subsystem of claim 1, wherein the first and second capacitors share an output current of the modular multilevel converter subsystem substantially equally if the first and second capacitors are placed in parallel relative to the first and second output terminals.

3. The modular multilevel converter subsystem of claim 1, wherein the first and second capacitors are sized the same.

4. The modular multilevel converter subsystem of claim 1, further comprising:

a first switching device;

a second switching device; and

a third switching device, wherein;

a zero voltage is present between the first and second output terminals of the modular multilevel converter subsystem if;

the second switching device is on; and

the first and third switching devices are off; and

a non-zero voltage is present between the first and second output terminals of the modular multilevel converter subsystem if;

the second switching device is off; and

the first and third switching devices are on.

5. The modular multilevel converter subsystem of claim 4, wherein at least one of the following is an insulated gate bipolar transistor:

the first switching device;

the second switching device; and

the third switching device.

6. A three-level two-terminal modular multilevel converter subsystem, comprising:

a storage capacitor; and

a flying capacitor.

7. The modular multilevel converter subsystem of claim 6, wherein:

the storage capacitor conducts a fundamental output current of the modular multilevel converter subsystem; and

the flying capacitor only conducts harmonic currents.

8. The modular multilevel converter subsystem of claim 6, wherein the flying capacitor is sized smaller than the storage capacitor.

9. The modular multilevel converter subsystem of claim 6, further comprising:

a first switching device;

a second switching device;

a third switching device; and

a fourth switching device, wherein the switching devices are configured to selectively generate a first voltage in two different ways.

10. The modular multilevel converter subsystem of claim 9, wherein at least one of the following is an insulated gate bipolar transistor:

the first switching device;

the second switching device;

the third switching device; and

the fourth switching device.

11. A modular multilevel converter system, comprising:

a plurality of series-connected two-terminal modular multilevel converter subsystems, wherein at least one of the subsystems comprises a first capacitor and a second capacitor, and wherein the at least one of the subsystems is configured to;

selectively place the first capacitor in series with the second capacitor; and

selectively place the first capacitor in parallel with the second capacitor relative to first and second output terminals of the at least one of the subsystems.

12. The modular multilevel converter system of claim 11, wherein the first and second capacitors share an output current of the at least one of the subsystems substantially equally if the first and second capacitors are placed in parallel relative to the first and second output terminals of the at least one of the subsystems.

13. The modular multilevel converter system of claim 11, wherein the first and second capacitors are sized the same.

14. The modular multilevel converter system of claim 11, wherein the at least one of the subsystems further comprises:

a first switching device;

a second switching device; and

a third switching device, wherein;

a zero voltage is present between the first and second output terminals of the at least one of the subsystems if;

the second switching device is on; and

the first and third switching devices are off; and

a non-zero voltage is present between the first and second output terminals of the at least one of the subsystems if;

the second switching device is off; and

the first and third switching devices are on.

15. The modular multilevel converter system of claim 14, wherein at least one of the following is an insulated gate bipolar transistor:

the first switching device;

the second switching device; and

the third switching device.

16. A modular multilevel converter system, comprising:

a plurality of series-connected two-terminal modular multilevel converter subsystems, wherein at least one of the subsystems comprises;

a storage capacitor; and

a flying capacitor.

17. The modular multilevel converter system of claim 16, wherein:

the storage capacitor of the at least one of the subsystems conducts a fundamental output current of the at least one of the subsystems; and

the flying capacitor of the at least one of the subsystems only conducts harmonic currents.

18. The modular multilevel converter system of claim 16, wherein the flying capacitor is sized smaller than the storage capacitor.

19. The modular multilevel converter system of claim 16, wherein the at least one of the subsystems further comprises:

a first switching device;

a second switching device;

a third switching device; and

a fourth switching device, wherein the switching devices are configured to selectively generate a first voltage in two different ways.

20. The modular multilevel converter system of claim 19, wherein at least one of the following is an insulated gate bipolar transistor:

the first switching device;

the second switching device;

the third switching device; and

the fourth switching device.