Motor drive with synchronized timing

• US 7,148,635 B1
• Filed: 09/21/2005
• Issued: 12/12/2006
• Est. Priority Date: 09/21/2005
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Piefer, Richard W., Rehm, Thomas J., Matsuo, Takayoshi
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US11/231,628
• Time in Patent Office: 447 Days
• Field of Search: 318/85, 318/34, 318/41, 318/68, 318/52
• US Class Current: 318/85
• CPC Class Codes: B41F 13/0045 Electric driving devices
• CPC Class Codes: B65H 2403/943 Electronic shaft arrangement
• CPC Class Codes: B65H 45/00 Folding thin material specially adapted for the manufacture or treatment of particular products, see appropriate subclasses, e.g. D06F89/00
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/41381 Torque disturbance observer to estimate inertia
• CPC Class Codes: G05B 2219/43117 Torque compensation as function of position reference, feedback of speed and position
• CPC Class Codes: H04L 12/43 with synchronous transmission, e.g. time division multiplex [TDM], slotted rings

Abstract

A motor control system for controlling a motor includes control logic and a motor controller. The control logic is operable to generate a control signal at a first periodic time responsive to a synchronization signal. The motor controller is operable to generate a drive signal for the motor based on the reference signal at a second periodic time synchronized with respect to the first periodic time.

Claims

1. A motor control system for controlling a motor, comprising:

a first processor configured to generate a reference control signal at a first periodic time responsive to a synchronization signal;

a second processor configured to generate a drive signal for the motor based on the reference control signal at a second periodic time; and

wherein the second periodic time is delayed from the first periodic time by a first time interval associated with the time required for the first processor to generate the reference control signal and a predetermined delay interval selected to minimize a staleness of the reference control signal.

12. The system of claim 1, further comprising:

a synchronization unit operable to generate a synchronization signal;

wherein the first processor is part of a control logic of one of a plurality of drive units controlled in accordance with a common reference signal, wherein the control logic is operable to generate a torque reference signal that is part of the reference control signal at the first periodic time responsive to the synchronization signal, the torque reference signal being generated based on the common reference signal and at least one feedback signal; and

wherein the second processor is part of a motor controller operable to generate a drive signal for an associated motor based on the torque reference signal at the second periodic time.

13. The system of claim 1, wherein the reference control signal includes a torque reference signal and wherein the first time interval is selected to minimize a staleness of the torque reference signal.

2. An electronic line shaft, comprising:

a synchronization unit operable to generate a synchronization signal; and

a plurality of drive units controlled in accordance with a common reference signal, each drive unit including;

control logic operable to generate a torque reference signal at a first periodic time responsive to the synchronization signal, the torque reference signal being generated based on the common reference signal and at least one feedback signal; and

a motor controller operable to generate a drive signal for the motor based on the torque reference signal at a second periodic time, the second periodic time being delayed from the first periodic time by a first time interval associated with a time required for the control logic to generate the torque reference signal.

3. The electronic line shaft of claim 2, wherein the control logic is operable to generate the torque reference signal as a function of at least one of a velocity error signal, a position error signal, an inertia compensation signal, and an inertia adaption signal.

4. The electronic line shaft of claim 2, wherein the first time interval is selected to minimize a staleness of the torque reference signal.

5. The electronic line shaft of claim 2, wherein the control logic is operable to perform a velocity task and a position/reference task.

6. The electronic line shaft of claim 5, wherein the control logic is operable to perform the velocity task prior to the position reference task, and the position/reference task is operable to generate position/reference data for a subsequent iteration of the velocity task.

7. The electronic line shaft of claim 5, wherein the control logic is operable to execute the velocity task at a first frequency and the position/reference task at a second frequency less than the first frequency.

8. The electronic line shaft of claim 2, wherein the motor controller is operable to perform a pulse width modulation (PWM) task based on the torque reference signal to generate the drive signal.

9. The electronic line shaft of claim 8, wherein the control logic is operable to perform a system task to generate the torque reference signal at a first frequency, and the motor controller is operable to perform the PWM task at a second frequency greater than the first frequency.

10. The electronic line shaft of claim 9, wherein the second frequency is a function of the first periodic time and the first time interval.

11. The electronic line shaft of claim 2, wherein the control logic comprises a first processor operable to perform a system task, and the motor controller comprises a second processor operable to generate the drive signal.

14. A method for controlling multiple motors using a plurality of drive units controlled in accordance with a common reference signal, the method comprising:

generating a synchronization signal; and

responsive to the synchronization signal, generating a torque reference signal at a first periodic time;

generating a drive signal for each of the multiple motors based on the torque reference signal at a second periodic time, the second periodic time delayed from the first periodic time by at least a first time interval required to generate the torque reference signal.

15. The method of claim 14, wherein the at least one feedback signal includes at least one of a motor velocity feedback signal and a motor position feedback signal.

16. The method of claim 15, further comprising generating the torque reference signal as a function of at least one of a velocity error signal, a position error signal, an inertia compensation signal, and an inertia adaption signal.

17. The method of claim 14, wherein the second periodic time is delayed from the first periodic time by the first time interval plus a fixed delay time interval.

18. The method of claim 14, wherein the first time interval is selected to minimize a staleness of the torque reference signal.

19. The method of claim 14, further comprising executing a system task comprising a velocity task and a position/reference task to generate the torque reference signal and wherein the first time interval corresponds to at least a time required to complete the system task.

20. The method of claim 19, further comprising performing the velocity task prior to the position/reference task, and wherein the position/reference task is operable to generate position/reference data for a subsequent iteration of the velocity task.

21. The method of claim 20, further comprising executing the velocity task at a first frequency and the position/reference task at a second frequency less than the first frequency.

22. The method of claim 14, further comprising performing a pulse width modulation (PWM) task based on the torque reference signal to generate the drive signal.

23. The method of claim 22, further comprising performing a system task for generating the torque reference signal at a first frequency, and performing the PWM task at a second frequency greater than the first frequency.