Soft switching power electronic transformer

• US 8,446,743 B2
• Filed: 07/12/2010
• Issued: 05/21/2013
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Gupta, Ranjan Kumar, Mohapatra, Krushna Keshab, Mohan, Ned, Castelino, Gysler, Basu, Kaushik, Weise, Nathan
• Primary Examiner(s): Vu, Bao Q
• Application Number:
  US12/834,437
• Publication Number:
  US 20110007534A1
• Time in Patent Office: 1,044 Days
• Field of Search: 363/17, 363/34, 363/37, 363/95, 363/98, 363/131, 363/132
• US Class Current: 363/17
• CPC Class Codes: H02M 5/297 for conversion of frequency
• CPC Class Codes: H02M 7/217 using semiconductor devices only

Abstract

This patent document discloses power electronic transformers having a high-frequency link. An example apparatus include a transformer having a primary winding and a secondary winding, the transformer is configured to receive a primary power signal having a first frequency, a primary converter configured to selectively oscillate polarity of the primary windings with respect to the secondary windings at a second frequency, the second frequency substantially substantially higher than the first frequency, a secondary converter coupled to the secondary winding, the secondary converter configured to provide a load power signal using a high frequency power signal generated using the secondary winding. The secondary converter can be configured to reduce current flow in the primary winding when the polarity of the primary winding is switched, the reduced current follow is configured to reduce disturbances resulting from leakage inductance of the transformer.

Claims

1. An apparatus comprising:

a transformer having primary windings and secondary windings, the primary windings of the transformer configured to receive a first multi-phase power signal having a first frequency, wherein the primary windings include, for each phase of the multi-phase power signal, a first primary winding and a second primary winding magnetically coupled in direct phase opposition to the first primary winding;

a primary converter configured to generate a second multi-phase power signal having a second frequency at the secondary windings, the second frequency substantially higher than the first frequency, wherein the primary converter includes;

a first switch configured to couple together the first primary windings of each phase; and

a second switch configured to couple together the second primary windings of each phase;

a secondary converter coupled to the secondary windings, the secondary converter configured to provide a load power signal using the second multi-phase power signal; and

wherein the secondary converter is configured to reduce current flow in the primary windings at or near a switch event of at least one of the first and second switches of the primary converter, the reduced current flow configured to reduce disturbances from leakage inductance of the transformer.

2. The apparatus of claim 1, wherein the first switch and the second switch are two-quadrant switches.

3. The apparatus of claim 1, wherein the secondary converter is configured to couple to a direct current (DC) device.

4. The apparatus of claim 3, wherein the primary converter is configured to receive a three-phase power signal;

and the transformer is a three-phase transformer.

5. A method comprising:

receiving a first alternating current (AC) power signal having a first frequency at multiple first and second primary windings of a transformer;

selectively coupling together the first primary windings of the transformer to provide a second AC power signal having a second frequency using a first switch of a primary converter, wherein the second frequency is substantially higher than the first frequency;

selectively coupling together the second primary windings of the transformer to provide the second AC power signal using a second switch of the primary converter;

receiving the second AC power signal from a secondary winding of the transformer; and

modulating the second AC power signal using a secondary converter to generate an output power signal having third frequency.

6. The method of claim 5, wherein receiving the first AC power signal includes receiving a first three-phase AC power signal.

7. The method of claim 5, wherein receiving the second AC power signal includes receiving a second three-phase AC power signal from the secondary winding of the transformer.

8. The method of claim 5, wherein modulating the second AC power signal includes controlling the second converter to generate an average output power signal having a third frequency equal to substantially zero hertz.

9. The method of claim 5, wherein modulating the second AC power signal includes pulse width modulating the secondary power signal with a symmetric pulse.

10. The method of claim 5, wherein modulating the second AC power signal includes pulse width modulating the secondary power signal to provide a unity power factor at the primary converter.

11. A system comprising:

a power grid;

a high frequency link coupled to the power grid, wherein the high frequency link includes;

a transformer having primary windings and secondary windings, the primary windings of the transformer configured to receive a first multi-phase power signal having a first frequency, wherein the primary windings include, for each phase of the multi-phase power signal, a first primary winding and a second primary winding magnetically coupled in direct phase opposition to the first primary winding;

a primary converter configured to generate a second multi-phase power signal having a second frequency at the secondary windings, the second frequency substantially higher than the first frequency, wherein the primary converter includes;

a first switch configured to couple together the first primary windings of each phase; and

a second switch configured to couple together the second primary windings of each phase;

a secondary converter coupled to the secondary windings, the secondary converter configured to provide a load power signal using the second multi-phase power signal; and

wherein the secondary converter is configured to reduce current flow in the primary windings at or near a switch event of at least one of the first and second switches of the primary converter, the reduced current flow configured to reduce disturbances from leakage inductance of the transformer;

an electronic device coupled to the high frequency link, wherein the electronic device is at least one of a wind generator, a hybrid vehicle, a photovoltaic cell, or an energy storage device; and

wherein the high frequency link is configured to bi-directionally exchange energy between the power grid and the electronic device.