CHOKE FOR INTERLEAVED SWITCHING

• US 20170229937A1
• Filed: 09/03/2015
• Published: 08/10/2017
• Est. Priority Date: 09/12/2014
• Status: Active Grant

• Current Assignee: Vestas Wind Systems A/S
• Original Assignee: Vestas Wind Systems A/S
• Inventors: PEDERSEN, Tune
• Granted Patent: US 10,447,114 B2
• Time in Patent Office: Days
• CPC Class Codes: H01F 27/28 Coils; Windings; Conductive connections
• CPC Class Codes: H01F 38/00 Adaptations of transformers or inductances for specific applications or functions
• CPC Class Codes: H02K 7/183 wherein the turbine is a wind turbine adaptation of a wind turbine to an electric generator F03D9/25
• CPC Class Codes: H02M 1/0043 Converters switched with a phase shift, i.e. interleaved non-isolated DC/DC converters H02M3/1586
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/493 the static converters being arranged for operation in parallel

Abstract

When performing interleaved switching, a power generation system may include chokes for filtering out a high-frequency ripple. However, because the chokes are interconnected, a common mode current can flow between the different parallel converters. Instead of connecting all the outputs of a parallel converter to the same choke, the same phase of each of the parallel converters is sent to one of the chokes. For example, the first phase signals are sent to a first choke, the second phase signals are sent to a second choke, and so forth. By doing so, air gaps in the chokes can be manipulated in order to provide a different inductance for the common mode current than a grid current. For example, the air gaps may be arranged such that the inductance corresponding to the common mode current is greater than the inductance corresponding to the grid current.

Claims

1. A power generation system, comprising:

a generator configured to output a multi-phase power signal;

a power converter system comprising a plurality of parallel converter paths, each converter path is coupled to the generator to receive the multi-phase power signal; and

at least one electrical choke comprising a plurality of windings, wherein a first winding of the plurality of windings is coupled to a first output of a first path of the plurality of converter paths and a second winding of the plurality of windings is coupled to a first output of a second path of the plurality of converter paths, wherein the first output of the first path and first output of the second path correspond to a same phase of the multi-phase power signal.

2. The power generation system of claim 1, further comprising:

a second electrical choke coupled to a second output of the first path and a second output of the second path, wherein both the second output of the first path and the second output of the second path correspond to a different phase of the multi-phase power signal than the same phase.

3. The power generation system of claim 2, wherein the at least one electrical choke is configured to output a first phase of a power signal and the second electrical choke is configured to output a second phase of the power signal.

4. The power generation system of claim 1, wherein the multi-phase power signal comprises a three-phase power signal, wherein the same phase is a first phase of the three-phase power signal, and wherein the system further comprises:

a second electrical choke coupled to each of the plurality of converter paths and configured to output a second phase of the three-phase power signal;

a third electrical choke coupled to each of the plurality of converter paths and configured to output a third phase of the three-phase power signal.

5. The power generation system of claim 4, wherein the at least one electrical choke is configured to receive a first plurality of outputs from the plurality of converter paths that corresponds to only the first phase, the second electrical choke is configured to receive a second plurality of outputs from the plurality of converter paths that corresponds to only the second phase, and the third electrical choke is configured to receive a third plurality of outputs from each of the plurality of converter paths that corresponds to only the third phase.

6. The power generation system of claim 1, wherein the at least one electrical choke comprises a first air gap configured to affect an inductance of a grid current flowing through the at least one electrical choke from the power converter system to a load but not affect an inductance of a common mode current flowing between at least two of the plurality of parallel converter paths.

7. The power generation system of claim 6, wherein the at least one electrical choke comprises a second air gap configured to affect both the inductance of the grid current and the inductance of the common mode current.

8. The power generation system of claim 1, wherein a third winding of the plurality of windings is coupled to a second output of the first path and a fourth winding of the plurality of windings is coupled to a second output of the second path, wherein the second output of the first path and the second output of the second path correspond to different phases of the multi-phase power signal

9. A wind turbine, comprising:

a generator configured to output a multi-phase power signal;

a power converter system comprising a plurality of parallel converter paths, each converter path is coupled to the generator to receive the multi-phase power signal; and

at least one electrical choke comprising a plurality of windings, wherein a first winding of the plurality of windings is coupled to a first output of a first path of the plurality of converter paths and a second winding of the plurality of windings is coupled to a first output of a second path of the plurality of converter paths, wherein the first output of the first path and first output of the second path correspond to a same phase of the multi-phase power signal.

10. The wind turbine of claim 9, wherein the at least one electrical choke comprises a first air gap configured to affect an inductance of a grid current flowing through the at least one electrical choke from the power converter system to a load but not affect an inductance of a common mode current flowing between at least two of the plurality of parallel converter paths.

11. An electrical choke, comprising:

a core comprising;

a top portion and a bottom portion both extending in a common direction;

a first leg comprising a first end coupled to the top portion and a second end coupled to the bottom portion;

a second leg comprising a third end coupled to the top portion and a fourth end coupled to the bottom portion;

a winding wrapping around a portion of the first leg, wherein the second leg is not enclosed by any winding; and

a first inductance control element in the second leg, wherein a size of the first inductance control element is larger than a size of a second inductance control element in the core.

12. The electrical choke of claim 11, wherein the core further comprises a third leg with a fifth end coupled to the top portion and a second end coupled to the bottom portion, wherein the second leg is between the first and third legs.

13. The electrical choke of claim 12, further comprising a different winding wrapping around a portion of the third leg.

14. The electrical choke of claim 11, wherein first and second inductance control elements comprise one of a material with a lower magnetic permeability than a material of the core and an air gap.

15. The electrical choke of claim 11, wherein the first inductance control element is configured to affect an inductance of a grid current flowing through the winding but not affect an inductance of a common mode current flowing through the winding.