ELECTRIC MACHINE ASSEMBLY WITH FAIL-SAFE ARRANGEMENT

• US 20120275069A1
• Filed: 04/29/2011
• Published: 11/01/2012
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Dooley, Kevin Allan
• Granted Patent: US 8,878,468 B2
• Time in Patent Office: Days
• US Class Current: 361/31
• CPC Class Codes: H02H 7/06 for dynamo-electric generators; for synchronous capacitors
• CPC Class Codes: H02H 7/08 for dynamo-electric motors

Abstract

An electric machine assembly with fail-safe arrangement is described. The assembly comprises a stator including a plurality of windings and a cooperating rotor including at least one permanent magnet; a detector configured to detect DC current in at least one of the windings of the stator; and a bypass circuit configured to be activated upon detection of the DC current by the detector and to prevent at least some of the DC current from flowing into the at least one of the windings of the stator.

Claims

1. An electric machine assembly with fail-safe arrangement, the assembly comprising:

a stator including a plurality of windings and a cooperating rotor including at least one permanent magnet;

a detector configured to detect DC current in at least one of the windings of the stator; and

a bypass circuit configured to be activated upon detection of the DC current by the detector and configured to prevent at least some of the DC current from flowing into the at least one of the windings of the stator.

2. The assembly as defined in claim 1, wherein the bypass circuit is configured to short-circuit line connections of the windings of the stator.

3. The assembly as defined in claim 1, wherein the bypass circuit comprises a normally-open contactor.

4. The assembly as defined in claim 1, wherein the bypass circuit includes a plurality of normally-open contactors configured to short-circuit line connections of the windings of the stator upon closing of the normally-open contactors.

5. The assembly as defined in claim 4, wherein the normally-open contactors are configured to be closed by a common switching device.

6. The assembly as defined in claim 5, wherein the common switching device is configured to open a normally-closed contactor associated with at least one of a rectified output of the machine assembly and an input current to the machine assembly.

7. The assembly as defined in claim 5, wherein the common switching device is configured to open a normally-closed contactor associated with a control coil of the stator.

8. The assembly as defined in claim 4, wherein the normally-open contactors are configured to be closed simultaneously by a single action.

9. The assembly as defined in claim 1, wherein the stator includes three windings and the bypass circuit includes a corresponding number of normally-open contactors configured to short-circuit line connections of the windings to each other.

10. An electric machine assembly for use with a gas turbine engine, the assembly comprising:

a stator including a plurality of phase windings and a cooperating rotor including at least one permanent magnet;

a detector configured to detect a failure of a bridge connected to the phase windings via line connections; and

a normally open circuit configured to short-circuit the line connections upon detection of the failure by the detector.

11. The assembly as defined in claim 10, wherein the normally-open circuit comprises a plurality of normally-open contactors.

12. The assembly as defined in claim 11, wherein the normally-open contactors are configured to be closed by a common switching device.

13. The assembly as defined in claim 12, comprising a normally-closed contactor configured to be opened by the common switching device wherein the normally-closed contactor is associated with a control coil of the stator.

14. The assembly as defined in claim 10, wherein the failure of a bridge comprises DC current flowing in a line connection of one of the phase windings.

15. A method for controlling a permanent magnet machine in the event of a failure of a bridge associated with the machine, wherein the machine comprises a stator including a plurality of phase windings and a cooperating rotor including at least one permanent magnet, the method comprising:

detecting the failure of the bridge; and

establishing a short circuit between line connections of the phase windings.

16. The method as defined in claim 15, wherein establishing a short circuit comprises closing a normally-open contactor.

17. The method as defined in claim 15, wherein establishing a short circuit comprises closing a plurality of normally-open contactors using a single mechanical action.

18. The method as defined in claim 17, comprising opening a normally-closed contactor using the single mechanical action wherein the normally-closed contactor is associated with a control coil of the stator.

19. The method as defined in claim 17, comprising opening a normally-closed contactor using the single mechanical action wherein the normally-closed contactor is associated with at least one of a rectified output of the machine assembly and an input current to the machine assembly.

20. The method as defined in claim 15, wherein detection of the failure comprises the detection of DC current in one of the line connections of the phase windings.