Selectively lowering resistance of a constantly used portion of motor windings in an electric motor

• US 8,994,307 B2
• Filed: 03/01/2013
• Issued: 03/31/2015
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Bates, Allen K., Bui, Nhan X., Hancock, Reed A., Winarski, Daniel J.
• Primary Examiner(s): Chan, Kawing
• Assistant Examiner(s): Carrasquillo, Jorge L
• Application Number:
  US13/782,452
• Publication Number:
  US 20130229136A1
• Time in Patent Office: 760 Days
• Field of Search: 318/7, 318/400.09, 318/771, 318/495, 318/497, 318/496, 318/400.41, 318/376, 360/73.06, 360/73.01, 310/179, 310/184, 310/198
• US Class Current: 318/432
• CPC Class Codes: H02P 1/04 Means for controlling progress of starting sequence in dependence upon time or upon current, speed, or other motor parameter
• CPC Class Codes: H02P 25/18 with arrangements for switching the windings, e.g. with mechanical switches or relays
• CPC Class Codes: H02P 3/12 by short-circuit or resistive braking

Abstract

Dynamic reconfiguration-switching of motor windings in a motor is optimized between winding-configurations by selectively lowering resistance of a constantly used portion of one of the motor windings. Acceleration is traded off in favor of higher velocity upon detecting the electric motor in the electric vehicle is at an optimal angular-velocity for switching to an optimal lower torque constant and voltage constant. The total back electromotive force (BEMF) is prohibited from inhibiting further acceleration to a higher angular-velocity.

Claims

1. A method for switching motor windings within a motor using a processor device, the method comprising:

optimizing a dynamic reconfiguration-switching of a plurality of motor windings between a plurality of winding-configurations by selectively lowering resistance of a constantly used portion of one of the plurality of motor windings for trading off acceleration in favor of higher velocity upon detecting the motor is at an optimal angular-velocity for switching to an optimal lower torque constant and voltage constant thereby preventing a total back electromotive force (BE MF) from inhibiting further acceleration to a higher angular-velocity; and

using m simultaneous-linear equations, having m number of unknown variables, for determining a plurality of voltage constants, the optimal time, and the optimal angular-velocity for performing the dynamic reconfiguration-switching between each of the plurality of winding-configurations, wherein a number of the m simultaneous-linear equations increases, starting with one equation for a three-winding- configuration of the motor and adding an additional simultaneous equation for each additional one of the plurality of winding-configurations, and a number of the plurality of voltage constants equal to the correlating one of the plurality of winding-configurations.

2. The method of claim 1, further including performing the dynamic reconfiguration-switching between the plurality of motor windings using one of a wye connection and a delta connection system for the motor.

3. The method of claim 1, further including performing the dynamic reconfiguration-switching between the plurality of winding-configurations in a successive order when a velocity sensor detects the motor is at the optimal angular-velocity for switching the torque constant and the voltage constant.

4. The method of claim 1, further including trading off angular-acceleration for a greater angular-velocity as speed of the motor is increased whereby the torque constant, the voltage constant, and the angular-acceleration correspondingly decrease.

5. The method of claim 1, further including performing the dynamic reconfiguration-switching using a higher angular-acceleration at a lower angular-velocity upon slowing down the motor.

6. The method of claim 1 further including organizing the m simultaneous-linear equations, having the m number of unknown variables, into a tridiagonal system of linear equations, a coefficient matrix of the tridiagonal system of linear equations having 2'"'"'s along an entire main diagonal of the coefficient matrix, and negative 1'"'"'s along diagonals immediately adjacent to the main diagonal, and all other entries of the coefficient matrix being zero, and a right-hand-side vector comprising a first entry of 1, a last entry of N, denoting N times a maximum allowable angular-velocity V of the motor at a one hundred percent torque constant, and all other entries of the right-hand-side vector being zero.

7. The method of claim 6, further including, for a WCth-winding-configuration of the motor, performs each of:

increasing to an angular-velocity N times a capability of the motor with the one hundred percent torque constant and the voltage constant,

calculating an optional time for performing the dynamic reconfiguration-switching by first finding a total time for acceleration to an angular-velocity of NV and differentiating the total time with respect to vector of unknowns X and then setting each first derivatives to zero to find an optimal value of the vector of unknowns X to minimize the total time, and

taking a second derivative of the total time with respect to the vector of unknowns X, wherein a positive-second derivative indicates a value of the vector of unknowns X that minimizes and optimizes the total time for performing the dynamic reconfiguration-switching, where X is an unknown used for subdividing the one hundred percent torque constant of the motor into smaller units of the torque constant which allows the motor to go faster than V angular-velocity and up to the angular-velocity of NV where V is a maximum angular-velocity achieved with the one hundred percent torque constant, and N is an arbitrary value greater than 1, where WC is the a number of possible winding-configurations of the motor.

8. The method of claim 7, further including using the constantly used portion of one of the plurality of motor windings for the WCth-winding-configuration while accelerating up to the angular-velocity of NV, where V is a maximum angular-velocity achieved with the one hundred percent torque constant, and N is an arbitrary value greater than 1, where WC is a number of possible winding-configurations of the motor.

9. The method of claim 1, further including increasing a total angular velocity and decreasing the torque constant, the voltage constant, and angular-acceleration as a number of the plurality of motor windings of the motor increases.

10. The method of claim 1, further including activating a plurality of switches to connect the plurality of motor windings in a parallel configuration to reduce the total back-EMF from the plurality of motor windings and allow for greater angular-velocity of the motor.

11. The method of claim 1, further including activating a plurality of switches to bypass an electrical connection to at least one of the plurality of motor windings to provide a minimum back-EMF and allow for greater angular-velocity of the motor.

12. The method of claim 1, further including activating a plurality of switches to connect the plurality of motor windings in a serial configuration to maximize torque on the motor.

13. The method of claim 1, further including selectively activating the plurality of motor windings for each electrical phase of the motor to provide for multiple velocities.

14. The method of claim 1, further including activating a plurality of switches to disconnect the plurality of motor windings in a serial configuration to maximize torque on the motor.

15. The method of claim 1, wherein the dynamic reconfiguration-switching occurs between each of the plurality of winding-configurations at an optimal time for allowing a dynamic trade-off between the angular-velocity and angular-acceleration.

16. The method of claim 1, wherein the motor is at least one of an electric motor, a tape drive motor, and a brushless DC motor.

17. The method of claim 1, further including using the constantly used portion of one of the plurality of motor windings for each of a plurality of winding-configurations while accelerating up to the optimal angular-velocity.

18. The method of claim 1, further including using the constantly used portion of one of the plurality of motor windings while power is supplied to the motor.

19. The method of claim 18, further including applying the dynamic reconfiguration-switching of a plurality of motor windings between a plurality of winding-configurations to only those remaining portions of the plurality of motor windings for trading off acceleration in favor of higher velocity upon detecting the motor is at the optimal angular-velocity for switching to an optimal lower torque constant and voltage constant.

20. The method of claim 1, further including using square-cross-section wire for the constantly used portion of one of the plurality of motor windings, wherein the higher cross-sectional area of the square-cross-section wire of side “

D”

has a lower electrical resistance thereby consuming less power than traditional circular-cross-sectional wire of diameter “

D”

.

21. The method of claim 20, further including using a material for the square-cross-section wire having a resistivity equal to or less than copper.

22. A system for switching motor windings within a motor, the system comprising:

a motor having a plurality of motor windings,

a plurality of switches for controlling a current through the plurality of motor windings of the motor, and

a processor device in communication with the plurality of switches, wherein the processor device;

optimizes a dynamic reconfiguration-switching of a plurality of motor windings between a plurality of winding-configurations by selectively lowering resistance of a constantly used portion of one of the plurality of motor windings for trading off acceleration in favor of higher velocity upon detecting the motor is at an optimal angular-velocity for switching to an optimal lower torque constant and voltage constant thereby preventing a total back electromotive force (BEMF) from inhibiting further acceleration to a higher angular-velocity, and

uses m simultaneous-linear equations, having m number of unknown variables, for determining a plurality of voltage constants, the optimal time, and the optimal angular-velocity for performing the dynamic reconfiguration-switching between each of the plurality of winding-configurations, wherein a number of the m simultaneous-linear equations increases, starting with one equation for a three-winding-configuration of the motor and adding an additional simultaneous equation for each additional one of the plurality of winding-configurations, and a number of the plurality of voltage constants equal to the correlating one of the plurality of winding-configurations.

23. The system of claim 22, wherein the processor device performs the dynamic reconfiguration-switching between the plurality of motor windings using one of a wye connection and a delta connection system for the motor.

24. The system of claim 22, wherein the processor device performs the dynamic reconfiguration-switching between the plurality of winding-configurations in a successive order when a velocity sensor detects the motor is at the optimal angular-velocity for switching the torque constant and the voltage constant.

25. The system of claim 22, wherein the processor device trades off angular-acceleration for a greater angular-velocity as speed of the motor is increased whereby the torque constant, the voltage constant, and the angular-acceleration correspondingly decrease.

26. The system of claim 22, wherein the processor device performs the dynamic reconfiguration-switching using a higher angular-acceleration at a lower angular-velocity upon slowing down the motor.

27. The system of claim 22, wherein the processor device organizes the m simultaneous-linear equations, having the m number of unknown variables, into a tridiagonal system of linear equations, a coefficient matrix of the tridiagonal system of linear equations having 2'"'"'s along an entire main diagonal of the coefficient matrix, and negative 1'"'"'s along diagonals immediately adjacent to the main diagonal, and all other entries of the coefficient matrix being zero, and a right-hand-side vector comprising a first entry of 1, a last entry of N, denoting N times a maximum allowable angular-velocity V of the motor at a one hundred percent torque constant, and all other entries of the right-hand-side vector being zero.

28. The system of claim 27, wherein the processor device, for a WCth-winding-configuration of the motor, performs each of:

increasing to an angular-velocity N times a capability of the motor with the one hundred percent torque constant and the voltage constant,

calculating an optional time for performing the dynamic reconfiguration-switching by first finding a total time for acceleration to an angular-velocity of NV and differentiating the total time with respect to vector of unknowns X and then setting each first derivatives to zero to find an optimal value of the vector of unknowns X to minimize the total time, and

taking a second derivative of the total time with respect to the vector of unknowns X, wherein a positive-second derivative indicates a value of the vector of unknowns X that minimizes and optimizes the total time for performing the dynamic reconfiguration-switching, where X is an unknown used for subdividing the one hundred percent torque constant of the motor into smaller units of the torque constant which allows the motor to go faster than V angular-velocity and up to the angular-velocity of NV where V is a maximum angular-velocity achieved with the one hundred percent torque constant, and N is an arbitrary value greater than 1, where WC is the a number of possible winding-configurations of the motor.

29. The system of claim 28, wherein the processor device uses the constantly used portion of one of the plurality of motor windings for the WCth-winding-configuration while accelerating up to the angular-velocity of NV, where V is a maximum angular-velocity achieved with the one hundred percent torque constant, and N is an arbitrary value greater than 1, where WC is a number of possible winding-configurations of the motor.

30. The system of claim 28, wherein the processor device increases a total angular velocity and decreasing the torque constant, the voltage constant, and angular-acceleration as a number of the plurality of motor windings of the motor increases.

31. The system of claim 30, wherein the processor device activates the plurality of switches to connect the plurality of motor windings in a parallel configuration to reduce the total back-EMF from the plurality of motor windings and allow for greater angular-velocity of the motor.

32. The system of claim 22, wherein the processor device activates the plurality of switches to bypass an electrical connection to at least one of the plurality of motor windings to provide a minimum back-EMF and allow for greater angular-velocity of the motor.

33. The system of claim 22, wherein the processor device activates the plurality of switches to connect the plurality of motor windings in a serial configuration to maximize torque on the motor.

34. The system of claim 22, wherein the processor device selectively activates the plurality of motor windings for each electrical phase of the motor to provide for multiple velocities.

35. The system of claim 22, wherein the processor device activates the plurality of switches to disconnect the plurality of motor windings in a serial configuration to maximize torque on the motor.

36. The system of claim 22, wherein the dynamic reconfiguration-switching occurs between each of the plurality of winding-configurations at an optimal time for allowing a dynamic trade-off between the angular-velocity and angular-acceleration.

37. The system of claim 22, wherein the motor is at least one of an electric motor, a tape drive motor, and a brushless DC motor.

38. The system of claim 22, wherein the processor device uses the constantly used portion of one of the plurality of motor windings for each of a plurality of winding-configurations while accelerating up to the optimal angular-velocity.

39. The system of claim 22, wherein the processor device uses the constantly used portion of one of the plurality of motor windings while power is supplied to the motor.

40. The system of claim 39, wherein the processor device applies the dynamic reconfiguration-switching of a plurality of motor windings between a plurality of winding-configurations to only those remaining portions of the plurality of motor windings for trading off acceleration in favor of higher velocity upon detecting the motor is at the optimal angular-velocity for switching to an optimal lower torque constant and voltage constant.

41. The system of claim 22, wherein the processor device uses square-cross-section wire for the constantly used portion of one of the plurality of motor windings, wherein the higher cross-sectional area of the square-cross-section wire of side “

D”

has a lower electrical resistance thereby consuming less power than traditional circular-cross-sectional wire of diameter “

D”

.

42. The system of claim 41, wherein the processor device uses a material for the square-cross-section wire having a resistivity equal to or less than copper.

43. A computer program product for switching motor windings within a motor using a processor device, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

a first executable portion that optimizes a dynamic reconfiguration-switching of a plurality of motor windings between a plurality of winding-configurations by selectively lowering resistance of a constantly used portion of one of the plurality of motor windings for trading off acceleration in favor of higher velocity upon detecting the motor is at an optimal angular-velocity for switching to an optimal lower torque constant and voltage constant thereby preventing a total back electromotive force (BEMF) from inhibiting further acceleration to a higher angular-velocity; and

a second executable portion that uses m simultaneous-linear equations, having m number of unknown variables, for determining a plurality of voltage constants, the optimal time, and the optimal angular-velocity for performing the dynamic reconfiguration-switching between each of the plurality of winding-configurations, wherein a number of the m simultaneous-linear equations increases, starting with one equation for a three-winding-configuration of the motor and adding an additional simultaneous equation for each additional one of the plurality of winding-configurations, and a number of the plurality of voltage constants equal to the correlating one of the plurality of winding-configurations.

44. The computer program product of claim 43, further including a second executable portion that performs the dynamic reconfiguration-switching between the plurality of motor windings using one of a wye connection and a delta connection system for the motor.

45. The computer program product of claim 43, further including a second executable portion that performs the dynamic reconfiguration-switching between the plurality of winding-configurations in a successive order when a velocity sensor detects the motor is at the optimal angular-velocity for switching the torque constant and the voltage constant.

46. The computer program product of claim 43, further including a second executable portion that trades off angular-acceleration for a greater angular-velocity as speed of the motor is increased whereby the torque constant, the voltage constant, and the angular-acceleration correspondingly decrease.

47. The computer program product of claim 43, further including a second executable portion that performs the dynamic reconfiguration-switching using a higher angular-acceleration at a lower angular-velocity upon slowing down the motor.

48. The computer program product of claim 43, further including a third executable portion that organizes the m simultaneous-linear equations, having the m number of unknown variables, into a tridiagonal system of linear equations, a coefficient matrix of the tridiagonal system of linear equations having 2'"'"'s along an entire main diagonal of the coefficient matrix, and negative 1'"'"'s along diagonals immediately adjacent to the main diagonal, and all other entries of the coefficient matrix being zero, and a right-hand-side vector comprising a first entry of 1, a last entry of N, denoting N times a maximum allowable angular-velocity V of the motor at a one hundred percent torque constant, and all other entries of the right-hand-side vector being zero.

49. The computer program product of claim 48, further including a fourth executable portion that, for a WCth-winding-configuration of the motor, performs each of:

increasing to an angular-velocity N times a capability of the motor with the one hundred percent torque constant and the voltage constant,

calculating an optional time for performing the dynamic reconfiguration-switching by first finding a total time for acceleration to an angular-velocity of NV and differentiating the total time with respect to vector of unknowns X and then setting each first derivatives to zero to find an optimal value of the vector of unknowns X to minimize the total time, and

taking a second derivative of the total time with respect to the vector of unknowns X, wherein a positive-second derivative indicates a value of the vector of unknowns X that minimizes and optimizes the total time for performing the dynamic reconfiguration-switching, where X is an unknown used for subdividing the one hundred percent torque constant of the motor into smaller units of the torque constant which allows the motor to go faster than V angular-velocity and up to the angular-velocity of NV where V is a maximum angular-velocity achieved with the one hundred percent torque constant, and N is an arbitrary value greater than 1, where WC is the a number of possible winding-configurations of the motor.

50. The computer program product of claim 49, further including a fifth executable portion that increases a total angular velocity and decreasing the torque constant, the voltage constant, and angular-acceleration as a number of the plurality of motor windings of the motor increases.

51. The computer program product of claim 50, further including a sixth executable portion that activates the plurality of switches to connect the plurality of motor windings in a parallel configuration to reduce the total back-EMF from the plurality of motor windings and allow for greater angular-velocity of the motor.

52. The computer program product of claim 49, further including a fifth executable portion that uses the constantly used portion of one of the plurality of motor windings for a WCth-winding-configuration while accelerating up to the angular-velocity of NV, where V is a maximum angular-velocity achieved with the one hundred percent torque constant, and N is an arbitrary value greater than 1, where WC is a number of possible winding-configurations of the motor.

53. The computer program product of claim 43, further including a second executable portion that activates the plurality of switches to bypass an electrical connection to at least one of the plurality of motor windings to provide a minimum back-EMF and allow for greater angular-velocity of the motor.

54. The computer program product of claim 43, further including a second executable portion that activates the plurality of switches to connect the plurality of motor windings in a serial configuration to maximize torque on the motor.

55. The computer program product of claim 43, further including a second executable portion that selectively activates the plurality of motor windings for each electrical phase of the motor to provide for multiple velocities.

56. The computer program product of claim 43, further including a second executable portion that activates the plurality of switches to disconnect the plurality of motor windings in a serial configuration to maximize torque on the motor.

57. The computer program product of claim 43, wherein the dynamic reconfiguration-switching occurs between each of the plurality of winding-configurations at an optimal time for allowing a dynamic trade-off between the angular-velocity and angular-acceleration.

58. The computer program product of claim 43, wherein the motor is at least one of an electric motor, a tape drive motor, and a brushless DC motor.

59. The computer program product of claim 43, further including a second executable portion that uses the constantly used portion of one of the plurality of motor windings for each of a plurality of winding-configurations while accelerating up to the optimal angular-velocity.

60. The computer program product of claim 43, further including a second executable portion that uses the constantly used portion of one of the plurality of motor windings while power is supplied to the motor.

61. The computer program product of claim 60, further including a third executable portion that applies the dynamic reconfiguration-switching of a plurality of motor windings between a plurality of winding-configurations to only those remaining portions of the plurality of motor windings for trading off acceleration in favor of higher velocity upon detecting the motor is at the optimal angular-velocity for switching to an optimal lower torque constant and voltage constant.

62. The computer program product of claim 43, further including a second executable portion that uses square-cross-section wire for the constantly used portion of one of the plurality of motor windings, wherein the higher cross-sectional area of the square-cross-section wire of side “

D”

has a lower electrical resistance thereby consuming less power than traditional circular-cross-sectional wire of diameter “

D”

.

63. The computer program product of claim 62, further including a third executable portion that uses a material for the square-cross-section wire having a resistivity equal to or less than copper.