Electric motor control device, method and program

• US 6,525,498 B2
• Filed: 03/29/2001
• Issued: 02/25/2003
• Est. Priority Date: 03/30/2000
• Status: Expired due to Fees

• Current Assignee: Establissements Andre Zalkin
• Original Assignee: Etablissements Andre Zalkin
• Inventors: Zalkin, Daniel, Ostrowski, Laurent, Matthys, Philippe
• Primary Examiner(s): Nappi, Robert E.
• Assistant Examiner(s): Duda, Rina I.
• Application Number:
  US09/819,685
• Publication Number:
  US 20010026135A1
• Time in Patent Office: 698 Days
• Field of Search: 318/432, 318/434, 533/17, 533/315, 534/90
• US Class Current: 318/432
• CPC Class Codes: B67B 3/208 Electrical means responsive to the torque applied and acting on motor control means, e.g. strain gauges or power measurement means B67B3/2093 takes precedence
• CPC Class Codes: H02P 5/74 controlling two or more ac dynamo-electric motors H02P5/46, H02P5/60 take precedence
• CPC Class Codes: H02P 6/04 Arrangements for controlling or regulating the speed or torque of more than one motor H02P6/10 takes precedence
• CPC Class Codes: H02P 6/34 Modelling or simulation for control purposes

Abstract

A device for controlling an electric motor measures the current I_m drawn by the motor and the torque C_m supplied by the motor. It includes a power supply 4 for the motor and an initialization unit 16 capable of generating a torque set point C_c and of receiving and processing information relating to the current I_m and the torque C_m to deduce therefrom a relationship between the set point C_c, the torque C_m and the current I_m in order to be able to determine the torque C_m from the set point C_c and the current I_m.

Claims

1. A device for controlling an electric motor, said device including means for measuring a current I_m drawn by said motor, means for measuring torque supplied by said motor, power supply means for said motor, and an initialization unit capable of generating a torque set point C_c and of receiving and processing information relating to said current I_m and a measured torque C_m to deduce therefrom a relationship between said set point C_c, the measured torque C_m and said current I_m in order to be able to determine an applied torque C_a from said set point C_c and said current I_m.

2. The device claimed in claim 1 wherein said means for measuring said torque C_m supplied by said motor are removable.

3. The device claimed in claim 1 further including a calculation unit associated with memory means and a user interface, a first data bus between said initialization unit and said power supply means of said motor, and a second data bus between said initialization unit and said calculation unit.

4. The device claimed in claim 1 wherein said means for measuring said torque C_m are provided with a removable calibrator.

5. The device according to claim 1, wherein said initialization unit is a central processing unit.

6. An electromechanical system including a device for controlling an electric motor, said device including means for measuring a current I_m drawn by said motor, means for measuring a torque supplied by said motor, power supply means for said motor, and an initialization unit capable of generating a torque set point C_c and of receiving and processing information relating to said current I_m and a measured torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine an applied torque C_a from said set point C_c and said current I_m.

7. The system claimed in claim 6 wherein said means for measuring said torque C_m supplied by said motor are removable.

8. The system claimed in claim 6 further including a calculation unit associated with memory means and a user interface, a first data bus between said initialization unit and said power supply means of said motor, and a second data bus between said initialization unit and said calculation unit.

9. The system claimed in claim 6 wherein said means for measuring said torque C_m are provided with a removable calibrator.

10. The system according to claim 6, wherein said initialization unit is a central processing unit.

11. A method of controlling an electric motor in which an initialization unit generates a torque set point C_c addressed to power supply means of said motor, current measuring means measure a current I_m drawn by said motor, torque measuring means measure a torque supplied by said motor, said initialization unit receives and processes information relating to said current I_m and a measured torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine an applied torque C_a from said set point C_c and said current I_m.

12. The method claimed in claim 11 wherein said torque measuring means are installed beforehand and then removed after measuring at least one value of said torque C_m.

13. The method claimed in claim 11 wherein said initialization unit generates three torque set point values C_c, said current measuring means measure n values of said current I_m drawn by said motor, where n is greater than 2, said torque measuring means measure n values of said torque C_m, and said initialization unit receives and processes n values relating to said current I_m and said torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine an applied torque C_a from only said set point C_c and said current I_m.

14. The method claimed in claim 13 wherein said initialization unit calculates three coefficients a, b, c of a second order equation relating to said set point C_c and said torque C_a and three coefficients a′

, b′

, c′

of a second order equation linking said current I_m and said torque C_m.

15. The method according to claim 11, wherein said initialization unit is a central processing unit.

16. A computer program including program code means for implementing the steps of a method of controlling an electric motor in which an initialization unit generates a torque set point C_c addressed to power supply means of said motor, current measuring means measure the current I_m drawn by said motor, torque measuring means measure a torque supplied by said motor, said initialization unit receives and processes information relating to said current I_m and a measured torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine an applied torque C_a from said set point C_c and said current I_m.

17. The program claimed in claim 16 wherein said torque measuring means are installed beforehand and then removed after measuring at least one value of said torque C_m.

18. The program claimed in claim 16 wherein said initialization unit generates three torque set point values C_c, said current measuring means measure n values of said current I_m drawn by said motor, where n is greater than 2, said torque measuring means measure n values of said torque C_m, and said initialization unit receives and processes n values relating to said current I_m and said torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine an applied torque C_a from only said set point C_c and said current I_m.

19. The program claimed in claim 18 wherein said initialization unit calculates three coefficients a, b, c of a second order equation relating to set point C_c and said torque C_m and three coefficients a′

, b′

, c′

of a second order equation linking said current I_m and said torque C_a.

20. A medium which can be read by a device for reading program code means stored therein and which are adapted to implement the steps of a method of controlling an electric motor in which an initialization unit generates a torque set point C_c addressed to power supply means of said motor, current measuring means measure the current I_m drawn by said motor, torque measuring means measure a torque supplied by said motor, said initialization unit receives and processes information relating to said current I_m and a measured torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine an applied torque C_a from said set point C_c and said current I_m.

21. The medium claimed in claim 20 wherein said torque measuring means are installed beforehand and then removed after measuring at least one value of said torque C_m.

22. The medium claimed in claim 20 wherein said initialization unit generates three torque set point values C_c, said current measuring means measure n values of said current I_m drawn by said motor, where n is greater than 2, said torque measuring means measure n values of said torque C_m, and said initialization unit receives and processes n values relating to said current I_m and said torque C_m to deduce therefrom a relationship between said set point C_c, said torque C_m and said current I_m in order to be able to determine said torque C_a from only said set point C_c and said current I_m.

23. The medium claimed in claim 22 wherein said initialization unit calculates three coefficients a, b, c of a second order equation relating to set point C_c and said torque C_a and three coefficients a′

, b′

, c′

of a second order equation linking said current I_m and said torque C_a.

24. A device for controlling an electric motor, said device including at least one current measuring module for measuring the current I_m drawn by said motor, a torque measuring system for measuring torque supplied by said motor, a power supply for said motor, and a central processing unit capable of generating torque set point C_c and of receiving and processing information relating to said current I_m and the measured torque C_m to deduce information therefrom a relationship between said set point torque C_c, the measured torque C_m, and said current I_m in order to be able to determine the applied torque C_a from said set point torque C_c and said current I_m.