Method for detecting a locked axle on a locomotive AC traction motor

• US 6,532,405 B1
• Filed: 08/09/2000
• Issued: 03/11/2003
• Est. Priority Date: 08/09/2000
• Status: Expired due to Term

• Current Assignee: GE Global Sourcing LLC (Westinghouse Air Brake Technologies Corporation)
• Original Assignee: General Electric Company
• Inventors: Daigle, Jeffrey Louis, Kumar, Ajith Kuttannair
• Primary Examiner(s): Louis-Jacques, Jacques H.
• Assistant Examiner(s): Broadhead, Brian J.
• Application Number:
  US09/634,192
• Time in Patent Office: 944 Days
• Field of Search: 361/31, 361/57, 361/87, 361/93.1, 361/94, 701/19, 701/22, 701/20, 701/81, 318/71, 318/782, 318/798, 318/825, 318/826, 318/268, 318/455, 318/474, 318/476, 318/490, 318/459, 288/909, 288/903, 288/904, 104/288, 324/522, 324/772, 324/177, 105/61
• US Class Current: 701/19
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 3/00 Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption methods or circuit arrangements for monitoring or controlling batteries or fuel cells B60L58/00

Abstract

An exemplary embodiment of the invention is a method for detecting a potentially locked axle on a vehicle propelled by an AC motor. The method includes conducting a speed test by estimating axle speed and comparing estimated axle speed to measured vehicle speed. The existence of a potential locked axle condition is determined based on the comparing of estimated axle speed to measured vehicle speed. Additional tests are disclosed for determining a potential locked axle condition and a sensor fault condition.

Claims

1. A method for detecting a potentially locked axle on a vehicle propelled by an AC motor, comprising:

conducting a speed test by estimating axle speed utilizing at least one of a torque and a current of said AC motor and comparing the estimated axle speed to measured vehicle speed;

determining the existence of a potential locked axle condition based on the comparing of estimated axle speed to measured vehicle speed; and

wherein said conducting is executed while said AC motor is providing tractive power.

2. A method as claimed in claim 1 further comprising:

conducting a short circuit test by determining a maximum motor current threshold based upon a phase to neutral short circuit model for an AC induction motor and comparing the maximum motor current threshold with measured motor current;

determining the existence of a potential locked axle condition based on the comparing of maximum motor current threshold with measured motor current.

3. A method as claimed in claim 2 wherein the result of said short circuit test is logged in a short circuit fault counter such that measured motor current in excess of the maximum current threshold increments the counter and measured motor current less than the maximum current threshold decrements the counter.

4. A method as claimed in claim 3 wherein the value of said short circuit fault counter is compared to a predetermined limit value.

5. A method as claimed in claim 4 wherein the predetermined limit value of said short circuit fault counter is established to identify a fault condition of a potential locked axle.

6. A method as claimed in claim 1 further comprising:

conducting a high current test by determining an expected high command motor current based upon torque and flux relationships and comparing the expected high command motor current to measured motor current;

determining the existence of a potential locked axle condition based on the comparing of expected high command motor current to measured motor current.

7. A method as claimed in claim 6 wherein the result of the high current test is logged in a high current fault counter such that measured motor current in excess of the expected high current threshold increments the counter and measured motor current less than the high current threshold decrements the counter.

8. A method as claimed in claim 7 wherein the value of said high current fault counter is compared to a predetermined limit value.

9. A method as claimed in claim 8 wherein the predetermined limit value of said high current fault counter is established to identify a fault condition of a potential locked axle.

10. A method as claimed in claim 1 further comprising:

conducting an open circuit test by determining a minimum motor current threshold based upon a phase to nuetral open circuit model for an AC induction motor and comparing the minimum motor current threshold with measurement motor current;

determining the existence of a potienal locked axle condition based on the comparing of minimum motor current threshold with measured motor current.

11. A method as claimed in claim 10 wherein the result of said open circuit test is logged in an open circuit fault counter such that measured motor current less than the minimum current threshold increments the counter and measured motor current in excess of the minimum current threshold decrements the counter.

12. A method as claimed in claimed in claim 11 wherein the value of said open circuit fault counter is compared to a predetermined limit value.

13. A method as claimed in claim 12 wherein the predetermined limit value of said speed fault counter is established to identify a sensor fault condition.

14. A method as claimed in claim 1 further comprising:

conducting a low current test by determining expected low command current based upon torque and flux relationships and comparing the low command current to measured motor current; and

determining the existence of a potential locked axle condition based on the comparing the low command current to measured motor current.

15. A method as claimed in claim 14 wherein the result of the low current test is logged in a low current fault counter such that measured motor current less than the expected low current threshold increments the counter and measured motor current excess of the low current threshold decrements the counter.

16. A method as claimed in claim 15 wherein the value of said low current fault counter is compared to a predetermined limit value.

17. A method as claimed in claim 16 wherein the predetermined limit value of said low current fault counter is established to identify a sensor fault condition.

18. A method as claimed in claim 1 wherein the result of the speed test is logged in a speed fault counter such that estimated axle speed less than the calculated axle speed threshold increments the counter and estimated axle speed in excess of the minimum calculated axle threshold decrements the counter.

19. A method as claimed in claim 18 wherein the value of said speed fault counter is compared to a predetermined limit value.

20. A method as claimed in claim 19 wherein the predetermined limit value of said speed fault counter is established to identify a sensor fault condition.

21. A method as claimed in claim 1 wherein said estimating is executed without an axle speed sensor.

22. A method for detecting a potentially locked axle on a vehicle propelled by an AC motor, comprising:

conducting a speed test by estimating axle speed utilizing at least one of a torque and a current of said AC motor and comparing estimated axle speed to measured vehicle speed;

conducting a short circuit test by determining a maximum motor current threshold based upon a phase to neutral short circuit model for an AC induction motor and comparing the maximum motor current threshold to measured motor current;

conducting a high current test by determining an expected high command motor current based upon torque and flux relationships and comparing the high command motor current to measured motor current;

conducting an open circuit test by determining a minimum motor current threshold based upon a phase to neutral open circuit model for an AC induction motor and comparing the minimum motor current threshold with measured motor current;

conducting a low current test by determining an expected low command current based upon torque and flux relationships and comparing the low command current to measured motor current; and

determining the existence of a potential locked axle condition based on the results of one or more of the speed test, short circuit test, high current test, open circuit test and low current test; and

wherein said conducting is executed while said AC motor is providing tractive power.

23. A method as claimed in claim 22 wherein the result of the speed test is logged in a speed fault counter such that estimated axle speed less than the calculated axle speed threshold increments the counter and estimated axle speed in excess of the minimum calculated axle threshold decrements the counter.

24. A method as claimed in claim 23 wherein the value of said speed fault counter is compared to a predetermined limit value.

25. A method as claimed in claim 24 wherein the predetermined limit value of said speed fault counter is established to identify a sensor fault condition.

26. A method of claim 22 wherein the result of said short circuit test is logged in a short circuit fault counter such that measured motor current in excess of the maximum current threshold increments the counter and measured motor current less than the maximum current threshold decrements the counter.

27. A method as claimed in claim 26 wherein the value of said short circuit fault counter is compared to a predetermined limit value.

28. A method as claimed in claim 27 wherein the predetermined limit value of said short circuit fault counter is established to identify a fault condition of a potential locked axle.

29. A method as claimed in claim 22 wherein the result of the high current test is logged in a high current fault counter such that measured motor current in excess of the expected high current threshold increments the counter and measured motor current less than the high current threshold decrements the counter.

30. A method as claimed in claim 29 wherein the value of said high current fault counter is compared to a predetermined limit value.

31. A method as claimed in claim 30 wherein the predetermined limit value of said high current fault counter is established to identify a fault condition of a potential locked axle.

32. A method as claimed in claim 22 wherein the result of said open circuit test is logged in an open circuit fault counter such that measured motor current less than the minimum current threshold increments the counter and measured motor current in excess of the minimum current threshold decrements the counter.

33. A method as claimed in claim 32 wherein the value of said open circuit fault counter is compared to a predetermined limit value.

34. A method as claimed in claim 33 wherein the predetermined limit value of said open circuit fault counter is established to identify a sensor fault.

35. A method as claimed in claim 22 wherein the result of the low current test is logged in a low current fault counter such that measured motor current less than the expected low current threshold increments the counter and measured motor current in excess of the low current threshold decrements the counter.

36. A method as claimed in claim 35 wherein the value of said low current fault counter is compared to a predetermined limit value.

37. A method as claimed in claim 36 wherein the predetermined limit value of said low current fault counter is established to identify a sensor fault condition.