Switching methodology for ground referenced voltage controlled electric machine

• US 20030062868A1
• Filed: 10/01/2001
• Published: 04/03/2003
• Est. Priority Date: 10/01/2001
• Status: Abandoned Application

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Mir, Sayeed A., Skellenger, Dennis B.
• Application Number:
  US09/968,252
• Publication Number:
  US 20030062868A1
• Time in Patent Office: Days
• US Class Current: 318/599
• CPC Class Codes: H02P 6/14 Electronic commutators

Abstract

Disclosed is a system for dead time switching in a sinusoidally excited PM electric machine. The system comprises: a PM electric machine; a position sensor configured to measure a position of the electric machine and transmit a position signal; and a controller, where the controller receives the position signal. The controller executes a method comprising: obtaining a duty cycle command; generating a first control command signal to an upper switching device and a second control command signal to a lower switching device configured to drive the electric machine in response to the duty cycle command; and applying a dead time to the first control command signal to ensure that the upper switching device and the lower switching device are not conducting simultaneously; and wherein the dead time comprises a turn on delay and an advance turn off.

Claims

1. A method for ground referenced switching for a sinusoidally excited PM electric machine, the method comprising:

obtaining a duty cycle command;

generating a first control command signal to an upper switching device and a second control command signal to a lower switching device of an inverter configured to drive said electric machine in response to said duty cycle command;

applying a dead time to said first control command signal to ensure that said upper switching device and said lower switching device are not conducting simultaneously; and

wherein said dead time comprises a turn on delay and an advance turn off.

2. The method of claim 1 wherein said duty cycle command is responsive to at least one of a position signal, a torque command signal and a phase advance value.

3. The method of claim 1 wherein said turn on delay comprises a selected delay of the commanded turn on of said upper switching device relative to said duty cycle command.

4. The method of claim 3 wherein said advance turn off comprises a selected advance of the commanded turn off of said upper switching device relative to said duty cycle command.

5. The method of claim 1 wherein said turn off delay comprises a selected advance of the commanded turn off of said upper switching device relative to said duty cycle command.

6. The method of claim 1 wherein said dead time is configured to reduce torque ripple of said electric machine.

7. The method of claim 1 wherein said dead time is configured to reduce electromagnetic interference of said electric machine.

8. The method of claim 1 wherein said turn on delay is selected to exceed a propagation delay in operation of said upper switching device.

9. The method of claim 8 wherein said turn on delay is 400 nanoseconds.

10. The method of claim 8 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

11. The method of claim 10 wherein said advance turn off delay is 400 nanoseconds.

12. The method of claim 1 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

13. The method of claim 12 wherein said advance turn off is 400 nanoseconds.

14. The method of claim 1 wherein said duty cycle command is responsive to a linearization process responsive to a magnitude command.

15. The method of claim 14 wherein linearization process includes scheduling said magnitude command to generate a linearization offset.

16. The method of claim 15 wherein said scheduling is a look up table responsive to said magnitude command.

17. The method of claim 15 wherein linearization process includes scheduling said magnitude command to generate an adjusted magnitude command.

18. The method of claim 17 wherein said scheduling is a look up table responsive to said magnitude command.

19. The method of claim 14 wherein linearization process includes scheduling said magnitude command to generate an adjusted magnitude command.

20. The method of claim 19 wherein said scheduling is a look up table responsive to said magnitude command.

21. The method of claim 14 wherein linearization process includes combining a linearization offset and an adjusted magnitude command.

22. The method of claim 14 wherein said linearization process is configured to reduce torque ripple of said electric machine.

23. The method of claim 22 wherein said linearization process is configured to minimize torque ripple of said electric machine.

24. The method of claim 2 wherein said turn on delay comprises a selected delay of the commanded turn on of said upper switching device relative to said duty cycle command.

25. The method of claim 24 wherein said advance turn off comprises a selected advance of the commanded turn off of said upper switching device relative to said duty cycle command.

26. The method of claim 25 wherein said dead time is configured to reduce torque ripple of said electric machine.

27. The method of claim 26 wherein said dead time is configured to reduce electromagnetic interference of said electric machine.

28. The method of claim 27 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

29. The method of claim 28 wherein said turn on delay is 400 nanoseconds.

30. The method of claim 28 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

31. The method of claim 30 wherein said advance turn off is 400 nanoseconds.

32. The method of claim 31 wherein said duty cycle command is responsive to a linearization process responsive to a magnitude command.

33. The method of claim 32 wherein said linearization process is configured to reduce torque ripple of said electric machine.

34. The method of claim 32 wherein linearization process includes scheduling said magnitude command to generate a linearization offset.

35. The method of claim 34 wherein linearization process includes scheduling said magnitude command to generate an adjusted magnitude command.

36. The method of claim 35 wherein linearization process includes combining a linearization offset and an adjusted magnitude command.

37. A system for dead time switching in a sinusoidally excited PM electric machine, the system comprising:

a PM electric machine;

a position sensor configured to measure a rotor position of said electric machine and transmit a position signal;

a controller, said controller receiving said position signal, and

said controller executing a process comprising

obtaining a duty cycle command;

generating a first control command signal to an upper switching device and a second control command signal to a lower switching device configured to drive said electric machine in response to said duty cycle command;

applying a dead time to said first control command signal to ensure that said upper switching device and said lower switching device are not conducting simultaneously; and

wherein said dead time comprises a turn on delay and an advance turn off.

38. The system of claim 37 wherein said duty cycle command is responsive to at least one of a position signal, a torque command signal and a phase advance value.

39. The system of claim 37 wherein said turn on delay comprises a selected delay of the commanded turn on of said upper switching device relative to said duty cycle command.

40. The system of claim 39 wherein said advance turn off comprises a selected advance of the commanded turn off of said upper switching device relative to said duty cycle command.

41. The system of claim 37 wherein said turn off delay comprises a selected advance of the commanded turn off of said upper switching device relative to said duty cycle command.

42. The system of claim 37 wherein said dead time is configured to reduce torque ripple of said electric machine.

43. The system of claim 37 wherein said dead time is configured to reduce electromagnetic interference of said electric machine.

44. The system of claim 37 wherein said turn on delay is selected to exceed a propagation delay in operation of said upper switching device.

45. The system of claim 44 wherein said turn on delay is 400 nanoseconds.

46. The system of claim 44 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

47. The system of claim 46 wherein said advance turn off is 400 nanoseconds.

48. The system of claim 37 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

49. The system of claim 48 wherein said advance turn off is 400 nanoseconds.

50. The system of claim 37 wherein said controller includes an inverter comprised of said upper switching device and said lower switching device.

51. The system of claim 37 wherein said duty cycle command is responsive to a linearization process responsive to a magnitude command.

52. The system of claim 50 wherein linearization process includes scheduling said magnitude command to generate a linearization offset.

53. The system of claim 52 wherein said scheduling is a look up table responsive to said magnitude command.

54. The system of claim 52 wherein linearization process includes scheduling said magnitude command to generate an adjusted magnitude command.

55. The system of claim 54 wherein said scheduling is a look up table responsive to said magnitude command.

56. The system of claim 51 wherein linearization process includes scheduling said magnitude command to generate an adjusted magnitude command.

57. The system of claim 56 wherein said scheduling is a look up table responsive to said magnitude command.

58. The system of claim 51 wherein linearization process includes combining a linearization offset and an adjusted magnitude command.

59. The system of claim 51 wherein said linearization process is configured to reduce torque ripple of said electric machine.

60. The system of claim 59 wherein said linearization process is configured to minimize torque ripple of said electric machine.

61. The system of claim 38 wherein said turn on delay comprises a selected delay of the commanded turn on of said upper switching device relative to said duty cycle command.

62. The system of claim 61 wherein said advance turn off comprises a selected advance of the commanded turn off of said upper switching device relative to said duty cycle command.

63. The system of claim 62 wherein said dead time is configured to reduce torque ripple of said electric machine.

64. The system of claim 63 wherein said dead time is configured to reduce electromagnetic interference of said electric machine.

65. The system of claim 64 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

66. The system of claim 65 wherein said turn on delay is 400 nanoseconds.

67. The system of claim 65 wherein said advance turn off is selected to exceed a propagation delay in operation of said upper switching device.

68. The system of claim 67 wherein said advance turn off is 400 nanoseconds.

69. The system of claim 68 wherein said duty cycle command is responsive to a linearization process responsive to a magnitude command.

70. The system of claim 69 wherein said linearization process is configured to reduce torque ripple of said electric machine.

71. The system of claim 69 wherein linearization process includes scheduling said magnitude command to generate a linearization offset.

72. The system of claim 71 wherein linearization process includes scheduling said magnitude command to generate an adjusted magnitude command.

73. The system of claim 72 wherein linearization process includes combining a linearization offset and an adjusted magnitude command.

74. A method for ground referenced switching for reduced torque ripple in PM electric machine of an electric power steering system, the method comprising:

obtaining a duty cycle command;

generating a first control command signal to an upper switching device and a second control command signal to a lower switching device of an inverter configured to drive said electric machine in response to said duty cycle command;

applying a dead time to said first control command signal to ensure that said upper switching device and said lower switching device are not conducting simultaneously; and

wherein said dead time comprises a turn on delay and an advance turn off.

75. A storage medium encoded with a machine-readable computer program code for ground referenced switching for a sinusoidally excited PM electric machine, said storage medium including instructions for causing controller to implement a method comprising:

obtaining a duty cycle command;

generating a first control command signal to an upper switching device and a second control command signal to a lower switching device of an inverter configured to drive said electric machine in response to said duty cycle command;

applying a dead time to said first control command signal to ensure that said upper switching device and said lower switching device are not conducting simultaneously; and

wherein said dead time comprises a turn on delay and an advance turn off.

76. A computer data signal embodied in a carrier wave for ground referenced switching for a sinusoidally excited PM electric machine, said data signal comprising code configured to cause a controller to implement a method comprising:

obtaining a duty cycle command;

generating a first control command signal to an upper switching device and a second control command signal to a lower switching device of an inverter configured to drive said electric machine in response to said duty cycle command;

applying a dead time to said first control command signal to ensure that sat upper switching device and said lower switching device are not conducting simultaneously; and

wherein said dead time comprises a turn on delay and an advance turn off.