Transformerless multi-level power converter

• US 20060044857A1
• Filed: 08/25/2004
• Published: 03/02/2006
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Curtiss-Wright Electro-Mechanical Corporation (Curtiss-Wright Corporation)
• Original Assignee: Curtiss-Wright Electro-Mechanical Corporation (Curtiss-Wright Corporation)
• Inventors: Lemak, Thomas A.
• Granted Patent: US 7,219,673 B2
• Time in Patent Office: Days
• US Class Current: 363/132
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/4837 Flying capacitor converters
• 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

Abstract

The cascaded, multi-level inverter can be found in a variety of applications and in a variety of industries. The inverter is typically used as a motor drive to provide variable voltage and variable frequency to a propulsion motor or other loads requiring variable frequency and voltage. In the present invention, the transformer is eliminated and its function included in an existing generator by adding a plurality of secondary windings to supply the isolated voltages needed by the multi-level power converter. Two specific examples of the present invention include a cascaded, multi-level inverter, or a variant referred to as the multi-source, flying source inverter, whose ac input voltage is derived from an electromagnetic generatorator.

Claims

1. A multi-level power converter system, comprising:

an ac generator;

a plurality of secondary windings electrically connected to said generator; and

a semiconductor switching network including an output terminal attached to said plurality of secondary windings, such that the plurality of secondary windings provide dc voltage source(s) to the switching network to produce a time varying ac voltage at the output terminal.

2. The system of claim 1, wherein said system operates as a cascaded, multi-level, voltage clamped inverter.

3. The system of claim 1, wherein said system operates as a multi-source, flying source inverter.

4. The system of claim 1, wherein said system is used for maritime propulsion.

5. The system of claim 1, wherein said semiconductor switching network comprises Insulated Gate Bi-polar Transistors or other self-commutating semiconductor switching devices.

6. The system of claim 1, wherein said provided dc voltage source(s) are exactly one dc voltage source.

7. The system of claim 1, wherein said provided dc voltage source(s) are more than one dc voltage source.

8. The system of claim 1, wherein more than one time varying ac voltage is provided at said output terminal.

9. A maritime propulsion power system, comprising:

an ac generator;

a plurality of secondary windings electrically connected to said generator;

a semiconductor switching network including an output terminal attached to said plurality of secondary windings, such that the plurality of secondary windings provide dc voltage source(s) to the switching network to produce a time varying ac voltage at the output terminal; and

a means for propulsion deriving its ac power from said output terminal.

10. The system of claim 9, wherein said system operates as a cascaded, multi-level, voltage clamped inverter.

11. The system of claim 9, wherein said system operates as a multi-source, flying source inverter.

12. The system of claim 9, wherein said system is used for maritime propulsion.

13. The system of claim 9, wherein said semiconductor switching network comprises Insulated Gate Bi-polar Transistors or other self-commutating semiconductor switching devices.

14. The system of claim 9, wherein said provided dc voltage source(s) are exactly one dc voltage source.

15. The system of claim 9, wherein said provided dc voltage source(s) are more than one dc voltage source.

16. The system of claim 9, wherein more than one time varying ac voltage is provided at said output terminal.

17. The system of claim 9, wherein said propulsion means is a ship motor.

18. The system of claim 9, wherein said propulsion means drives a submarine.