APPARATUS HAVING A MOTOR, CONTROLLER FOR THE MOTOR, AND METHOD OF CONTROLLING THE MOTOR

• US 20060250102A1
• Filed: 05/03/2006
• Published: 11/09/2006
• Est. Priority Date: 05/04/2005
• Status: Active Grant

• Current Assignee: Wildeck, Inc. (Holden Industries Incorporated)
• Original Assignee: Wildeck, Inc. (Holden Industries Incorporated)
• Inventors: Payne, Stephen M.
• Granted Patent: US 7,408,317 B2
• Time in Patent Office: Days
• US Class Current: 318/569
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
• CPC Class Codes: G05B 2219/42288 Limit, stop drive current if axis obstructed, blocked, force against stop
• CPC Class Codes: G05B 2219/42289 Avoid overload servo motor, actuator limit servo torque

Abstract

A method, and a system of using the method, of controlling a motor having a rated capacity. The method includes determining the motor has been started, determining a plurality of operating parameters of the motor after the motor has started, determining a threshold from a portion of the operating parameters, comparing one of the determined operating parameters with the threshold, and operating the motor at a level corresponding to below the rated capacity when one of the determined operating parameters is greater than the threshold. When an electric motor having a control system according to the present invention lifts a load, drives a machine, or starts other motions, the control system automatically adjusts to a power level that corresponds to the load. In this way, the motor will not be allowed to exert any power or force to the load in excess of what is necessary. If the machine being driven becomes jammed, binds, or draws more power for some unexpected reason, the motor will be shut down to reduce or to limit damage to the load or the machine.

Claims

1. A method of controlling a motor having a rated capacity, the method comprising:

determining the motor has been started;

determining a plurality of operating parameters of the motor after the motor has started;

determining a threshold from a portion of the operating parameters;

comparing one of the determined operating parameters with the threshold; and

operating the motor at a level corresponding to below the rated capacity when one of the determined operating parameters is greater than the threshold.

2. The method of claim 1, wherein the operating parameters comprise one of current drawn by the motor, a speed exhibited by the motor, a temperature of the motor, a pressure exhibited by the motor, and a torque generated by the motor, and wherein determining the operating parameters further comprises sensing one of an amount of the current drawn by the motor, the speed exhibited by the motor, the temperature of the motor, the pressure exhibited by the motor, and an amount of the torque generated by the motor.

3. The method of claim 1, wherein determining the operating parameters of the motor comprises sensing the operating parameters of the motor when an amount of current drawn by the motor has started to decrease after the motor has started.

4. The method of claim 1, wherein determining the operating parameters of the motor comprises sensing the operating parameters of the motor after the motor has started for a period of time.

5. The method of claim 1, wherein determining the threshold from the portion of the operating parameters comprises:

determining a statistical value from one of an average, a mean, a variance, and a standard deviation with the portion of the operating parameters of the motor; and

determining a percentage of the statistical value.

6. The method of claim 5, wherein determining the threshold further comprises setting the threshold to a sum of the percentage and the statistical value.

7. The method of claim 1, wherein the level comprises one of a run level corresponding to a portion of the rated capacity, and a stop level corresponding to stopping the motor, and wherein operating the motor at the level comprises operating the motor at one of the run level and the stop level.

8. The method of claim 1, wherein operating the motor comprises operating the motor after the one of the determined operating parameter has been greater than the threshold for a period of time.

9. A method of controlling a motor having a rated capacity, the method comprising:

determining the motor has been started;

determining values of an initial set of operating parameters of the motor after the motor has started;

determining a statistical value of the values of the initial set of operating parameters;

adapting a set-point to the statistical value;

determining a value of a subsequent operating parameter of the motor after the values of the initial set of operating parameters have been determined;

determining a difference between the value of a subsequent operating parameter and the statistical value; and

stopping the motor when the difference is above an overload threshold for a period of time.

10. The method of claim 9, wherein the operating parameters comprise one of current drawn by the motor, a speed exhibited by the motor, a temperature of the motor, a pressure exhibited by the motor, and a torque generated by the motor, and wherein determining the values of the initial set of operating parameters comprises sensing one of an amount of the current drawn by the motor, the speed exhibited by the motor, a temperature of the motor, the pressure exhibited by the motor, and an amount of the torque generated by the motor.

11. The method of claim 9, wherein determining the values of the initial set of operating parameters comprises sensing the operating parameters of the motor when an amount of current drawn by the motor has started to decrease after the motor has started.

12. The method of claim 9, wherein determining the values of the initial set of operating parameters comprises sensing the operating parameters of the motor after the motor has started for a period of time.

13. The method of claim 9, wherein determining the statistical value comprises determining an average, a mean, a variance, and a standard deviation of the values of the operating parameters of the motor.

14. The method of claim 9, wherein adapting the set-point to the statistical value comprises setting the set-point to a value above the statistical value.

20. The system of claim 13, wherein the level comprises one of a run level corresponding to a portion of the rated capacity when the sensed operating parameter is greater than the operating threshold, and a stop level corresponding to stopping the motor when the sensed operating parameter is greater than the operating threshold.

15. A control system for a motor having a rated capacity, the system comprising:

a sensing module configured to determine a plurality of operating parameters of the motor after the motor has started; and

a controller configured to determine a threshold from a portion of the operating parameters, to compare one of the sensed operating parameters with the threshold, and to operate the motor at a level corresponding to below the rated capacity when one of the sensed operating parameters is greater than the threshold for a period of time.

16. The system of claim 15, wherein the operating parameters comprise one of an amount of current drawn by the motor, a speed exhibited by the motor, a temperature of the motor, a pressure exhibited by the motor, and a torque generated by the motor, and wherein the sensing module comprises one of a current sensor configured to sense the amount of current drawn by the motor, a speed sensor configured to sense the speed exhibited by the motor, a temperature sensor configured to sense a temperature of the motor, a pressure sensor configured to sense the pressure exhibited by the motor, and a torque sensor configured to sense a torque generated by the motor.

17. The system of claim 15, wherein the operating parameters comprise an amount of current drawn by the motor, wherein the controller comprises one of a timer is further configured to determine a period of time after which the controller starts to determine the threshold, and a comparator configured to compare the amount of current drawn with a current set-point above which the controller starts to determine the threshold.

18. The system of claim 15, wherein the controller is further configured to determine the threshold based on a statistical value comprising one of an average, a mean, a variance, and a standard deviation of the first and second operating parameters of the motor.

19. The system of claim 15, wherein the controller is further configured to set the threshold above the statistical value.