ELECTRIC MOTOR CONTROL

• US 20100194325A1
• Filed: 06/30/2008
• Published: 08/05/2010
• Est. Priority Date: 07/07/2007
• Status: Active Grant

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Dixon, Christopher David, Roberts, Christopher Digby
• Granted Patent: US 8,847,529 B2
• Time in Patent Office: Days
• US Class Current: 318/490
• CPC Class Codes: H02P 21/18 Estimation of position or speed
• CPC Class Codes: H02P 2203/09 Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage

Abstract

A control system for an electric motor comprises processing means arranged to perform a control process which includes monitoring electrical voltages applied to the motor and electrical currents in the motor, and determining from them the rotational position of the motor. The system is further arranged to monitor at least one parameter of the control process thereby to detect a stall condition of the motor.

Claims

1. A control system, for an electric motor arranged to have electrical voltages applied to it to generate electrical currents in it, the control system comprising a processor arranged to perform a control process which defines at least one parameter and includes monitoring the electrical voltages applied to the motor and the electrical currents generated in the motor, and determining from them a rotational position of the motor, the control system being further arranged to monitor the at least one parameter of the control process thereby to detect a stall condition of the motor.

2. The control system according to claim 1 wherein the at least one parameter includes an estimated acceleration of the motor.

3. The control system according to claim 2 arranged to define a predetermined value of the estimated acceleration and to detect the stall condition if the estimated acceleration is above the predetermined value of the estimated acceleration.

4. The control system according to claim 1 wherein the at least one parameter includes an estimated speed of the motor.

5. The control system according to claim 4 arranged to define a predetermined value of the estimated speed and to detect the stall condition if the estimated speed is below the predetermined value of the estimated speed.

6. The control system according to claim 1 wherein the at least one parameter includes a demanded current.

7. The control system according to claim 6 arranged to define a predetermined value of the demanded current and to detect the stall condition if the demanded current exceeds the predetermined value of the demanded current.

8. The control system according to claim 1 arranged to monitor repeatedly for detection of the stall condition, and to determine that a stall has occurred only if the stall condition occurs a predetermined number of times within a predetermined period of time.

9. The control system according to claim 1 arranged to perform a stall response action in response to detection of the stall condition.

10. The control system according to claim 9 wherein the stall response action includes providing a warning.

11. The control system according to claim 9 wherein the stall response action includes generating a control input.

12. The control system according to claim 11 wherein the control input is a current demand.

13. The control system according to claim 11 wherein the control input is a speed demand.

14. The control system according to claim 11 wherein the control input is a position signal.

16. The control system according to claim 3 also arranged to define a predetermined value of the estimated speed, with the control system being further arranged to detect the stall condition if both of the following conditions are met:

(a) the estimated acceleration is above the predetermined value of the estimated acceleration; and

(b) the estimated speed is below the predetermined value of the estimated speed.

17. The control system according to claim 16 arranged to monitor repeatedly for detection of the stall condition, and to determine that a stall has occurred only if the stall condition occurs a predetermined number of times within a predetermined period of time.

18. The control system according to claim 16 also arranged to define a predetermined value of the demanded current and to detect a stall condition if the demanded current exceeds the predetermined value of the demanded current, with the control system being further arranged to detect the stall condition if all of the following conditions are met:

(a) the estimated acceleration is above the predetermined value of the estimated acceleration;

(b) the estimated speed is below the predetermined value of the estimated speed; and

(c) the demanded current exceeds the predetermined value of the demanded current.

19. The control system according to claim 18 arranged to monitor repeatedly for detection of the stall condition, and to determine that a stall has occurred only if the stall condition occurs a predetermined number of times within a predetermined period of time.

20. The control system according to claim 3 arranged to monitor repeatedly for detection of the stall condition, and to determine that a stall has occurred only if the stall condition occurs a predetermined number of times within a predetermined period of time.

21. The control system according to claim 5 arranged to monitor repeatedly for detection of the stall condition, and to determine that a stall has occurred only if the stall condition occurs a predetermined number of times within a predetermined period of time.

15. (canceled)