Methods of torque estimation and compensation and systems thereof

Patent metadata

Field	Value
Publication number	US-9442029-B2
Application number	US-201314141709-A
Country	US
Kind code	B2
Filing date	Dec 27, 2013
Priority date	Dec 27, 2013
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

At least one example embodiment discloses a method including measuring phase currents associated with one or more stator windings of the machine, estimating terminal voltage values based on the measured phase currents representations of the machine and based on at least one of a duty cycle and a dead time ratio of the machine, transforming the terminal voltage values to derive direct and quadrature voltage representations consistent with the measured phase currents, determining a terminal power of one or more terminals of the machine, the terminal power directly based on one of the estimated terminal voltage values and direct and quadrature voltage representations of the machine and current command values and determining an estimated shaft torque of the machine based on the terminal power in accordance with at least one efficiency value based on machine parameters from a characterization of the machine.

First claim

What is claimed is:

1. A method of estimating shaft torque of an alternating current machine, the method comprising:
determining phase current command values;
estimating terminal voltage values based on actual phase current values and based on at least one of a duty cycle and a dead time ratio of the machine;
transforming the terminal voltage values to derive direct and quadrature voltage representations consistent with the current command values;
determining a terminal power of one or more terminals of the machine, the terminal power directly based on the direct and quadrature voltage representations of the machine and the current command values;
determining an estimated shaft torque of the machine based on the terminal power in accordance with at least one efficiency value based on machine parameters from a characterization of the machine; and
adjusting a torque command applied to the machine based on the estimated shaft torque.

2. The method according to claim 1 , wherein the adjusting adjusts the torque command applied to the machine such that the estimated shaft torque substantially equals a torque command for a sampling interval.

3. The method according to claim 2 , wherein the efficiency value varies with at least one of the torque command and a voltage over speed ratio.

4. The method of claim 2 , wherein the adjusting the torque command includes,
determining an error between the torque command and the estimated shaft torque,
generating a saturated torque value based on the error, and
generating the adjusted torque command based on the saturated torque value.

5. The method of claim 2 , wherein the adjusting the torque command includes,
generating the adjusted torque command based on a proportional integral (PI) function.

6. The method of claim 1 , further comprising:
determining an operating mode, the operating mode being one of a braking mode and a motoring mode; and
obtaining an efficiency table associated with the operating mode, the efficiency table including efficiency values corresponding to torque command percentages and voltage-speed ratios, respectively, the efficiency table being stored in a storage device and the efficiency table including the at least one efficiency value.

7. The method of claim 6 , further comprising:
receiving an input torque command percentage and an input voltage-speed ratio; and
determining an estimated shaft power based on the terminal power and the efficiency value corresponding to the input torque command percentage and the input voltage-speed ratio.

8. The method of claim 7 , wherein the determining the estimated shaft torque includes,
determining a shaft torque based on the estimated shaft power and speed of the shaft, and
determining the estimated shaft torque by filtering the shaft torque.

9. A method of estimating shaft torque of an alternating current machine, the method comprising:
measuring phase currents associated with one or more stator windings of the machine;
estimating terminal voltage values based on the measured phase currents representations of the machine and based on at least one of a duty cycle and a dead time ratio of the machine;
transforming the terminal voltage values to derive direct and quadrature voltage representations consistent with the measured phase currents;
determining a terminal power of one or more terminals of the machine, the terminal power directly based on one of the estimated terminal voltage values and direct and quadrature voltage representations of the machine and current command values; and
determining an estimated shaft torque of the machine based on the terminal power in accordance with at least one efficiency value based on machine parameters from a characterization of the machine.

10. The method according to claim 9 , further comprising:
adjusting a torque command applied to the machine such that the estimated shaft torque substantially equals a torque command for a sampling interval.

11. The method according to claim 10 , wherein the efficiency value varies with at least one of the torque command and a voltage over speed ratio.

12. The method of claim 10 , wherein the adjusting the torque command includes,
determining an error between the torque command and the estimated shaft torque,
generating a saturated torque value based on the error, and
generating the adjusted torque command based on the saturated torque value.

13. The method of claim 10 , wherein the adjusting the torque command includes,
generating the adjusted torque command based on a proportional integral (PI) function.

14. The method of claim 9 , further comprising:
determining an operating mode, the operating mode being one of a braking mode and a motoring mode; and
obtaining an efficiency table associated with the operating mode, the efficiency table including efficiency values corresponding to torque command percentages and voltage-speed ratios, respectively, the efficiency table being stored in a storage device and the efficiency table including the at least one efficiency value.

15. The method of claim 14 , further comprising:
receiving an input torque command percentage and an input voltage-speed ratio; and
determining an estimated shaft power based on the terminal power and the efficiency value corresponding to the input torque command percentage and the input voltage-speed ratio.

16. The method of claim 15 , wherein the determining the estimated shaft torque includes,
determining a shaft torque based on the estimated shaft power and speed of the shaft, and
determining the estimated shaft torque by filtering the shaft torque.

17. A system comprising:
a processor configured to,
determine phase current command values associated with an alternating current machine;
estimate terminal voltage values based on actual phase current values and based on at least one of a duty cycle and a dead time ratio of the alternating current machine;
transform the terminal voltage values to derive direct and quadrature voltage representations consistent with the current command values;
determine a terminal power of one or more terminals of the machine, the terminal power directly based on the direct and quadrature voltage representations of the machine and the current command values;
determine an estimated shaft torque of the machine based on the terminal power in accordance with at least one efficiency value based on machine parameters from a characterization of the machine; and
adjust a torque command applied to the machine based on the estimated shaft torque.

18. The system according to claim 17 , wherein the processor is configured to,
adjust the torque command applied to the machine such that the estimated shaft torque substantially equals a torque command for a sampling interval.

19. The system according to claim 18 , wherein the efficiency value varies with at least one of the torque command and a voltage over speed ratio.

20. The system of claim 18 , wherein the processor is configured to,
determine an error between the torque command and the estimated shaft torque,
generate a saturated torque value based on the error, and
generate the adjusted torque command based on the saturated torque value.

21. The system of claim 18 , wherein the processor is configured to,
generate the adjusted torque command based on a proportional integral (PI) function.

22. The system of claim 17 , wherein the processor is configured to,
determine an operating mode, the oper

Assignees

• Wu Long
• Zhao Yue
• Weber Anthony
• Deere & Co

Inventors

• Wu Long
• Zhao Yue
• Weber Anthony

Classifications

• G01L3/10

  involving electric or magnetic means for indicating · CPC title

• B62D6/10

  characterised by means for sensing {or determining} torque · CPC title

• G01L25/003

  for measuring torque · CPC title

• G01L3/26 Primary

  Devices for measuring efficiency, i.e. the ratio of power output to power input · CPC title

• H02P21/20 Primary

  Estimation of torque · CPC title