Wear-balanced electromagnetic motor control switching

Patent metadata

Field	Value
Publication number	US-10141143-B2
Application number	US-201514832885-A
Country	US
Kind code	B2
Filing date	Aug 21, 2015
Priority date	Nov 6, 2014
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

One embodiment describes a method that includes in a first switching operation of an electrical power switching system including three separately controllable single pole, single current-carrying path switching devices that provide three-phase power to a load, and control circuitry coupled to the switching devices to control closing and opening of the current-carrying paths, commanding at least one of the switching devices to open or close in advance of at least one other of the switching devices based upon a current zero-crossing or a predicted current zero-crossing of input three-phase power; and in subsequent switching operations alternating which of the three switching devices is closed or opened in advance of another of the switching devices.

First claim

The invention claimed is:

1. A method comprising:
in a first switching operation of an electrical power switching system comprising three separately controllable single pole, single current-carrying path switching devices configured to provide three-phase power to a load, and control circuitry coupled to the switching devices to control closing and opening of the current-carrying paths, commanding at least one of the switching devices to open or close in advance of at least one other of the switching devices based upon a current zero-crossing or a predicted current zero-crossing of input three-phase power; and
in subsequent switching operations alternating which of the three switching devices is closed or opened in advance of another of the switching devices.

2. The method of claim 1 , comprising determining the predicted current zero-crossing of at least one phase of the input three-phase power, and closing one of the switching devices at or within a desired time before the predicted current zero-crossing, and closing the remaining switching devices thereafter.

3. The method of claim 1 , wherein the switching device that is closed in advance of the at least one other switching device is changed every subsequent switching operation.

4. The method of claim 1 , comprising monitoring operation of the switching devices and alternating which of the three switching devices is closed or opened in advance of another of the switching devices based upon the monitored operation.

5. The method of claim 4 , wherein which of the three switching devices is closed or opened in advance of the other switching devices is selected based upon a wear indication of the switching devices.

6. The method of claim 5 , wherein selection of which of the three switching devices is closed or opened in advance of the other switching devices is based upon providing generally equal wear to all of the switching devices.

7. The method of claim 1 , wherein the switching devices are substantially identical.

8. An electrical power switching system, comprising:
a first switching device configured to selectively connect or disconnect phase A of three-phase electric power from a power source to a load;
a second switching device configured to selectively connect or disconnect phase B of the three-phase electric power from the power source to the load; and
a third switching device configured to selectively connect or disconnect phase C of the three-phase electric power from the source to the load; and
control circuitry configured to control operation of the first switching device, the second switching device, and the third switching device by:
instructing the first switching device to open or close before the second switching device and the third switching device during a first switching operation;
instructing the second switching device to open or close before the first switching device and the third switching device during a second switching operation; and
instructing the third switching device to open or close before the first switching device and the second switching device during a third switching operation.

9. The electrical switching system of claim 8 , wherein the control circuit is configured to:
instruct the first switching device to open based at least in part on when current conducted by the first switching device is zero; and
instruct the first switching device to close based at least in part on when voltage supplied to the first switching device from the power supply is zero.

10. The electrical switching system of claim 8 , the control circuitry is configured to instruct the electrical switching system to rotate between performing the first switching operation, the second switching operation, and the third switching operating.

11. The electrical switching system of claim 8 , wherein the first switching device, the second switching device, and the third switching device each comprises a single pole, single current-carrying path switching device.

12. The electrical switching system of claim 8 , wherein the control circuitry is configured to:
instruct the second switching device and the third switching device to open or close at substantially the same time during the first switching operation;
instruct the first switching device and the third switching device to open or close at substantially the same time during the second switching operation; and
instruct the first switching device and the second switching device to open or close at substantially the same time during the third switching operation.

13. A tangible, non-transitory computer-readable medium configured to store instructions executable by a processor, wherein the instructions comprise instructions to:
instruct, using the processor, an electrical power switching system to perform a first switching operation by:
opening or closing a first single pole, single current-carrying path switching device; and
subsequently opening or closing a second single pole, single current-carrying path switching device; and
instruct, using the processor, the electrical power switching system to perform a second switching operation by:
opening or closing the second single pole, single current-carrying path switching device; and
subsequently opening or closing the first single pole, single current-carrying path switching device.

14. The computer-readable medium of claim 13 , wherein:
the instructions to instruct the electrical power switching system to perform the first switching operation comprises instructions to open or close a third single pole, single-current carrying path switching device:
substantially simultaneously with the second single pole, single current-carrying path switching device;
substantially simultaneously with the first single pole, single current-carrying path switching device; or
after opening or closing the second single pole, single current-carrying path switching device.

15. The computer-readable medium of claim 13 , comprising instruction to instruct, using the processor, the electrical power switching system to perform a third switching operation by:
opening a third single pole, single current-carrying path switching device; and
subsequently opening the first single pole, single current-carrying path switching device and the second single pole, single current-carrying path switching device.

16. The computer-readable medium of claim 13 , comprising instructions to determine, using the processor, whether to perform the first switching operation or the second switching operation based at least in part on a wear indication of the first single pole, single current-carrying path switching device and a wear indication of the second single-pole, single current-carrying path switching device.

17. The computer-readable medium of claim 13 , comprising instructions to determine, using the processor, whether to perform the first switching operation or the second switching operation is based at least in part on providing generally equal wear to the first single pole, single current carrying path switching device and the second single pole, single current carrying path switching device.

18. The computer-readable medium of claim 13 , wherein the instructions to perform the first switching operation comprise instructions to:
open the first single pole, single current-carrying path switching device based at least in part on a first current zero-crossing; and
open the second single pole, single current-carrying path switching device based at least in part on a second current zero-crossing.

Assignees

• Rockwell Automation Tech Inc

Inventors

• Bock Christopher H
• Wieloch Christopher J
• Kinsella James J
• Dziekonski Stefan T
• Miller James P

Classifications

• H02P25/184

  wherein the motor speed is changed by switching from a delta to a star, e.g. wye, connection of its windings, or vice versa · CPC title

• H01H50/002 Primary

  particular to three-phase electromagnetic relays (synchronous switching H01H9/563) · CPC title

• H01H9/563 Primary

  for multipolar switches, e.g. different timing for different phases, selecting phase with first zero-crossing · CPC title

• H01H50/86

  Means for introducing a predetermined time delay between the initiation of the switching operation and the opening or closing of the contacts (circuit arrangements for introducing delay H01H47/18; short-circuited conducting sleeves, bands, or discs H01H50/46) · CPC title

• H02P1/32

  by star/delta switching · CPC title