Method and system for determinging a washing machine load unbalance

• US 20040211009A1
• Filed: 09/04/2003
• Published: 10/28/2004
• Est. Priority Date: 04/28/2003
• Status: Active Grant

• Current Assignee: Nidec Motor Corporation (Nidec Corporation)
• Original Assignee: Emerson Electric Company
• Inventors: Henderson, Michael I., Sadasivam, Vinodkumar, Marcinkiewicz, Joseph G., Marcetic, Darko, Rajarathnam, Anandan Velayutham, Murray, Peter
• Granted Patent: US 7,905,122 B2
• Time in Patent Office: Days
• US Class Current: 8/159
• CPC Class Codes: D06F 2103/24 Spin speed; Drum movements
• CPC Class Codes: D06F 2103/26 Imbalance; Noise level
• CPC Class Codes: D06F 2103/46 of the motor driving the drum
• CPC Class Codes: D06F 34/16 Imbalance

Abstract

A clothes washing machine system including a method of detecting a load unbalance. The washing machine system includes a cabinet having a drum rotatably mounted therein. A motor is coupled to the drum for rotating the drum within the cabinet. A memory device is accessible by a processor, such as a digital signal processor (DSP). The memory contains program code for implementing a method that includes determining the motor torque ripple, determining the motor speed, and determining the load unbalance mass based on the motor torque and speed.

Claims

1. A method of determining a load unbalance mass contained in a spinning washing machine drum driven by a motor, the method comprising:

determining the motor torque ripple;

determining the motor speed; and

determining the load unbalance mass based on the motor torque and speed.

2. The method of claim 1, wherein determining the motor torque ripple includes measuring the motor voltage and current.

3. The method of claim 1, further comprising constructing a mathematical model of the washing machine drum load describing the relationship between motor torque and the unbalance mass.

4. The method of claim 3, further comprising determining coefficients of the mathematical model using a parameter estimator.

5. The method of claim 4, wherein the parameter estimator is a recursive least squares estimator.

6. The method of claim 1, further comprising determining the combined inertia of the washing machine drum and the unbalance mass.

7. The method of claim 6, wherein the motor torque is compensated for the combined inertia.

8. The method of claim 6, wherein determining the combined inertia includes running the motor through a predetermined speed profile.

9. The method of claim 6, wherein determining the combined inertia includes running the motor at a first predetermined speed, and accelerating the motor to a second predetermined speed.

10. The method of claim 9, wherein the motor is accelerated substantially linearly from the first predetermined speed to the second predetermined speed.

11. The method of claim 6, wherein determining the combined inertia includes fluctuating the motor speed about a predetermined speed value.

12. The method of claim 11, wherein fluctuating the motor speed includes applying a speed demand signal to a speed controller, and applying a dither signal to the speed demand signal.

13. The method of claim 1, wherein determining the unbalance mass includes running the motor at a predetermined speed for a predetermined time period.

14. The method of claim 1, wherein determining the motor torque ripple includes determining the motor torque and speed are determined at a plurality of sample points.

15. The method of claim 1, further comprising determining the motor acceleration.

16. The method of claim 15, wherein the motor acceleration is calculated based on the motor speed.

17. The method of claim 1, further comprising determining the washing machine drum angular position.

18. The method of claim 17, wherein the washing machine drum angular position is calculated based on the motor speed.

19. A clothes washing machine system, comprising:

a cabinet;

a drum rotatably mounted within the cabinet;

a motor operably coupled to the drum for rotating the drum within the cabinet;

a processor connected to the motor; and

a memory device accessible by the processor and storing program code implementing a method comprising determining the motor torque ripple, determining the motor speed, and determining a load unbalance mass based on the motor torque and speed.

20. The clothes washing machine system of claim 19, further comprising a device for measuring the drum rotation speed.

21. The clothes washing machine system of claim 19, wherein the processor receives indications of the motor current and voltage, and wherein the method implemented by the program code includes determining the position of the rotor based on the motor current and voltage.

22. The clothes washing machine system of claim 19, wherein the method implemented by the program code includes determining the combined inertia of the washing machine drum and the unbalance mass.

23. The clothes washing machine system of claim 21, wherein the method implemented by the program code includes compensating the determined motor torque for the combined inertia.

24. A clothes washing machine system, comprising:

a cabinet;

a drum rotatably mounted within the cabinet;

a sensorless motor operably coupled to the drum for rotating the drum within the cabinet;

a processor connected to the motor, the processor receiving indications of the motor current and voltage; and

a memory device accessible by the processor, and storing program code implementing a method of determining a load unbalance mass based on the indications of the motor current and voltage.

25. The clothes washing machine system of claim 24, wherein the method implemented by the program code includes determining the motor torque ripple, determining the motor speed, and determining a load unbalance mass based on the motor torque and speed.

26. The clothes washing machine system of claim 25, wherein the method implemented by the program code includes compensating the determined motor torque for for the combined inertia.

27. A system for determining a load unbalance mass contained in a spinning washing machine drum driven by a motor, comprising:

a processor; and

a memory device accessible by the processor, and storing program code implementing a method comprising determining the motor torque ripple, determining the motor speed, and determining the load unbalance mass based on the motor torque and speed.

28. A program storage device storing program code implementing a method of determining a load unbalance mass contained in a spinning washing machine drum driven by a motor, the method comprising:

determining the motor torque ripple;

determining the motor speed; and

determining the load unbalance mass based on the motor torque and speed.

29. The program storage device of claim 28, wherein determining the motor torque ripple includes measuring the motor voltage and current.

30. The program storage device of claim 28, further storing a model of the washing machine drum load describing the relationship between motor torque and the unbalance mass.

31. The program storage device of claim 28, wherein the method further comprises determining the combined inertia of the washing machine drum and the unbalance mass.

32. The program storage device of claim 31, wherein the motor torque is compensated for the combined inertia.

33. The program storage device of claim 31, wherein determining the combined inertia includes running the motor through a predetermined speed profile.

34. The program storage device of claim 31, wherein determining the combined inertia includes running the motor at a first predetermined speed, and accelerating the motor to a second predetermined speed.

35. The program storage device of claim 31, wherein the motor is accelerated substantially linearly from the first predetermined speed to the second predetermined speed.

36. The program storage device of claim 31, wherein determining the unbalance mass includes running the motor at a predetermined speed for a predetermined time period.

37. The program storage device of claim 31, wherein determining the combined inertia includes fluctuating the motor speed about a predetermined speed value.

38. The program storage device of claim 37, wherein fluctuating the motor speed includes applying a speed demand signal to a speed controller, and applying a dither signal to the speed demand signal.

39. The program storage device of claim 28, wherein determining the motor torque ripple includes determining the motor torque and speed at a plurality of sample points.

40. The program storage device of claim 28, further comprising determining the motor acceleration.

41. The program storage device of claim 40, further comprising determining the washing machine drum angular position.