Method and device for servo-controlling DC motor

• US 6,608,459 B2
• Filed: 12/10/2001
• Issued: 08/19/2003
• Est. Priority Date: 12/11/2000
• Status: Active Grant

• Current Assignee: Daihen Corporation
• Original Assignee: Daihen Corporation
• Inventors: Kasagami, Fumio, Noda, Toshikazu
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US10/016,553
• Publication Number:
  US 20020177920A1
• Time in Patent Office: 617 Days
• Field of Search: 318/560, 318/561, 318/802, 388/804, 388/811
• US Class Current: 318/560
• CPC Class Codes: H02P 6/085 in a bridge configuration

Abstract

PWM controlling means (4) for inputting PWM signals corresponding to PWM target values to electric power supplier (3) in order to servo-controlling DC motor (2) comprises synchronizing control part (41), PWM computing part (50), selecting part of PWM target value (45) and PWM commanding part (46). The synchronizing control part (41) instructs the commencement of the PWM computation, selection of PWM target value and PWM command allotted to some of the infinitesimal intervals obtained by dividing processing term, on which PWM signals regulating the electric power supplied to the motor (2) are allotted, into n equal parts, and terminates one cycle for a series of the process and/or computation predetermined within one processing term. PWM target values corresponding to plural control target values (DP₀, DV₀, DT₀) are computed in parallel so that the servo-control of motor can be operated in quick response to the change of control mode.

Claims

1. Method for servo-controlling DC motor, controlling the electric power supplied to the motor according to PWM signals corresponding to PWM target values computed on the basis of both the motor information detected at the present time and the control input information including control target values, comprising;

to compute PWM target value corresponding to the control mode designated by said control input information without lapping the computation of PWM target values corresponding to other control modes, spending one or plural infinitesimal intervals obtained by dividing a processing term of period T, when PWM signals regulating the electric power supplied to the motor are allotted, into n equal parts,

to select one PWM target value according to the control mode designated by said control input information from among PWM target values computed every control mode during the present processing term,

to output PWM signals corresponding to PWM selection values, which are selected at the processing term shortly previous to the present term, every infinitesimal interval of the present processing term, and

to carry out the process and/or computation allotted every infinitesimal interval in the timing scheduled in one processing term and to terminate the process and/or computation within the present processing term.

2. Method for servo-controlling DC motor according to claim 1, wherein:

said PWM selection value is replaced with one of the PWM value for other control modes, which is less than PWM maximum allowable value under said other control modes, in the case that the PWM target value for the control mode designated by the control input information is more than FWM maximum allowable value corresponding to the maximum allowable current for the motor when PWM selection value is selected from among PWM target values.

3. Method for servo-controlling DC motor according to claim 1, wherein:

PWM gradual values for gradually getting close to a new PWM selection value by spending the succeeding several processing terms are computed in the case that said new PWM selection value is different from the previous PWM selection value, and PWM signals corresponding to said PWM gradual values are output so as not to shock the motor.

4. Method for servo-controlling DC motor according to claim 1, wherein:

said control target values are at least two chosen among three targets for controlling position, velocity and torque.

5. Method for servo-controlling DC motor according to claim 1, wherein:

all the control target values to be computed and a control mode to be designated are assigned to temporary values before carrying out the process and/or computation on the initial processing term of servo-control of motor, and the process and/or computation on the initial processing term are carried out after the predetermined lapse from the commencement of the servo-control.

6. Method for servo-controlling DC motor according to claim 1, wherein:

the positional information of a motor is generated by adding the increment or decrement obtained by cumulating the positional signals of motor output shaft, which are detected during n infinitesimal intervals shortly previous to the infinitesimal interval computing the present position of output shaft, to the positional information obtained in the infinitesimal interval of T in time before.

7. Method for servo-controlling DC motor according to claim 1, wherein:

the positional information of a motor is generated by adding the increment or the decrement obtained by cumulating the positional signals of motor output shaft, which are detected during all of infinitesimal intervals of the processing term shortly previous to the present term, to the positional information obtained on the processing term of 2 periods before.

8. A method for servo-controlling DC motor according to claim 6, wherein:

the velocity information of a motor is assigned to the increment or the decrement of the positional signals of motor output shaft.

9. Method for servo-controlling DC motor according to claim 1, wherein:

said every infinitesimal interval is charged with at least both detecting positional signals of motor output shaft and outputtting PWM signals.

10. Method for servo-controlling DC motor according to claim 9, wherein:

either detection of positional signals of motor output shaft or output of PWM signals is carried out at the beginning of the infinitesimal interval, and the rest is done just after the termination of the preceded.

11. Method for servo-controlling DC motor according to claim 7, wherein:

the velocity information of a motor is assigned to the increment or the decrement of the positional signals of motor output shaft.

12. Method for servo-controlling DC motor, controlling the electric power supplied to the motor according to PWM signals corresponding to PWM target values computed on the basis of both the motor information detected at the present time and the control input information including control target values, comprising;

to keep one or plural infinitesimal intervals obtained by dividing the processing term of period T, when PWM signals regulating the electric power supplied to the motor are allotted, into n equal parts in order to enable to individually compute plural PWM target values,

to compute PWM target value according to the control mode only designated by said control input information for the present processing term,

to output PWM signals corresponding to PWM target values, which are computed on the processing term shortly previous to the present term, every infinitesimal interval of the present processing term, and

to carry out the process and/or computation allotted every infinitesimal interval in the timing scheduled in one processing term and to terminate the process and/or computation for getting PWM target values according to control mode designated within the processing term.

13. Method for servo-controlling DC motor according to claim 12, wherein:

PWM gradual values for gradually getting close to a new PWM target value by spending the succeeding several processing terms are computed in the case that said new PWM target value is different from the previous PWM target value, and PWM signals corresponding to said PWM gradual values are output so as not to shock the motor.

14. Method for servo-controlling DC motor according to claim 12, wherein:

said control target values are at least two chosen among three targets for controlling position, velocity and torque.

15. Method for servo-controlling DC motor according to claim 12, wherein:

all of control target values to be computed and a control mode to be designated are assigned to temporary values before carrying out the process and/or computation on the initial processing term of servo-control of motor, and the process and/or computation on the initial processing term are carried out after the predetermined lapse from the commencement of the servo-control.

16. Method for servo-controlling DC motor according to claim 12, wherein:

the positional information of a motor is generated by adding the increment or decrement obtained by cumulating the positional signals of motor output shaft, which are detected during n infinitesimal intervals shortly previous to the infinitesimal interval computing the present position of output shaft, to the positional information obtained in the infinitesimal interval of T in time before.

17. Method for servo-controlling DC motor according to claim 12, wherein:

the positional information of a motor is generated by adding the increment or the decrement obtained by cumulating the positional signals of motor output shaft, which are detected during all of infinitesimal intervals of the processing term shortly previous to the present term, to the positional information obtained on the processing term of 2 periods before.

18. Method for servo-controlling DC motor according to claim 12, wherein:

said every infinitesimal interval is charged with at least both detecting positional signals of motor output shaft and outputtting PWM signals.

19. Device for servo-controlling DC motor, equipping PWM controlling means 4 which computes PWM target values on the basis of both the present information detected by a motor information detector and the control input information, including control target values, commanded by a superior controller 7, and outputs PWM signals corresponding to said PWM target values to electric power supplier 3, said PWM control means 4, comprising;

synchronizing control part 41 for instructing the commencement of the process and/or computation allotted to some of the infinitesimal intervals obtained by dividing processing term of period T, when FWM signals regulating the electric power supplied to the motor are allotted, into n equal parts, and for terminating one cycle for a series of the process and/or computation predetermined within said one processing term,

selecting part of PWM target value 45 for selecting one PWM target value among the PWM target values computed every control mode within the present processing term, and

PWM commanding part 46 for receiving PWM selection value selected on the processing term shortly previous to the present term as a PWM commanding value, and for outputting the PWM signals corresponding to said PWM commanding value every infinitesimal interval of present processing term.

20. Device for servo-controlling DC motor according to claim 19, wherein:

said selecting part of PWM target value 45 is a selecting part of target value for designated mode 451 for selecting PWM target value corresponding to the control mode designated in the control input information as a PWM selection value from among PWM target values individually computed based on each of control target values.

21. Device for servo-controlling DC motor according to claim 20, wherein:

all of the PWM target values input to selecting part of target value for designated mode 451 are limited to PWM maximum allowable value corresponding to the maximum allowable current of the motor or less.

22. Device for servo-controlling DC motor according to claim 19, wherein:

said selecting part of PWM target value 45 is a selecting part of target value for automatically changing control mode 451b for replacing the target value selected from among PWM target values computed based on each of control target values as a PWM target value for the control mode designated by the control input information with one of the PWM target values for other control modes, which is less than PWM maximum allowable value under said other control modes, in the case that said target value selected from among PWM target values is more than PWM maximum allowable value corresponding to the maximum allowable current for the motor for getting PWM selection value.

23. Device for servo-controlling DC motor according to claim 22, wherein:

PWM target value computed in association with at least torque out of PWM target values input to selecting part of target value for automatically changing control mode 451b is limited to PWM maximum allowable value corresponding to the maximum allowable current of the motor under the torque control or less.

24. Device for servo-controlling DC motor according to claim 19, wherein:

calculating part of PWM gradual values 452 for computing PWM gradual values for gradually getting close to a new PWM selection value by spending the succeeding several processing terms in the case that said new PWM selection value is different from the previous PWM selection value, and for outputting said PWM gradual values to PWM commanding part 46 as a PWM commanding value Pr<sub>−

Sm</sub> is provided between said selecting part of PWM target value 45 and PWM commanding part 46 so as to output PWM signals which does not shock the motor.

25. Device for servo-controlling DC motor according to claim 19, wherein:

said PWM computing part 50 is provided with at least two computing parts out of computing part of PWM target value for position 441P, computing part of PWM target value for velocity 442V and computing part of PWM target for torque 443T.

26. Device for servo-controlling DC motor according to claim 25, wherein:

said computing part of PWM target value for position 441P comprises position calculating part 421, which calculates the present position of motor output shaft based on the information measured by positional signal detector 42, and computing part for controlling position 441, which computes the position to be achieved based on both information obtained by said position calculating part 421 and target value for controlling position DP₀ and computes PWM target value corresponding to said position to be achieved.

27. Device for servo-controlling DC motor according to claim 25, wherein:

said computing part of PWM target value for velocity 442V comprises velocity calculating part 422, which calculates the present velocity of motor based on the information measured by positional signal detector 42, and computing part for controlling velocity 442, which computes the velocity to be achieved based on both information obtained by said velocity calculating part 422 and target value for controlling velocity DV₀ and computes PWM target value corresponding to said velocity to be achieved.

28. Device for servo-controlling DC motor according to claim 25, wherein:

said computing part of PWM target value for torque 443T comprises computing part for controlling torque 443, which computes the target to be achieved based on both information obtained by current detecting part 43 and target value for controlling torque DT₀ and computes PWM target value corresponding to said torque to be achieved.

29. Device for servo-controlling DC motor according to claim 19, wherein:

information input/output part 5 is provided for transmitting information between the PWM controlling means 4 and the superior controller 7, which has the receiving part 51 for receiving control input information including control target values and control modes from superior controller 7 in response to the instructions of said synchronizing control part 41 and for transferring said control input information to the proper storing part belong to said PWM computing Dart 50, individually.

30. Device for servo-controlling DC motor according to claim 19, wherein:

every information input/output part 5 having its own proper (ID) number 53 are connected by a serial communication line 61 with each other so that any of position, velocity or torque control for DC motor 2 equipped corresponding to individual information input/output part 5 may be instructed or charged (by said superior controller 7) through said serial communication line 61.

31. Device for servo-controlling DC motor according to claim 30, wherein:

said superior controller 7, PWM controlling means 4 and electric power supplier 3 are arranged near said DC motor 2, the mobile 75 providing with plural DC motors 2 and main controller 76 comprising said superior controller 7 are connected by a serial communication line 61 and power lines for servo motors 62.

32. Device for servo-controlling DC motor according to claim 19, wherein:

said PWM controlling means 4 and information input/output part 5 are assembled into one chip of MPU, to which both positional signal Ea, Eb output from an encoder 1 and current signals output from an ammeter 31 are directly input and from which PWM signals are directly output to electric power supplier 3, so that the chip can directly communicate with said superior controller 7.

33. Device for servo-controlling DC motor to claim 19, wherein:

said motor is a brushless-type DC motor 2N.

42. Device for servo-controlling DC motor according to claim 29, wherein:

said information input/output part 5 has the transmitting part 52 for replying the present data of position, velocity or torque inquired through said receiving part 51 to said superior controller 7 in response to the instructions of said synchronizing control part 41.

43. Device for servo-controlling DC motor according to claim 42, wherein:

transistors used in said electric power supplier 3 are fixed to the movable member of mobile 75 equipping with DC motor 2, being air-cooled due to the behavior of said movable member, thereby, promoting the heat-radiation of the transistors.

34. Device for servo-controlling DC motor, equipping PWM controlling means 4 which computes PWM target values on the basis of both the present information detected by a motor information detector and the control input information, including control target values, commanded by a superior controller 7, and outputs PWM signals corresponding to said PWM target values to electric power supplier 3, said PWM control means 4, comprising;

synchronizing control part 41 for instructing the commencement of the process and/or computation allotted to some of the infinitesimal intervals obtained by dividing processing term of period T, when PWM signals regulating the electric power supplied to the motor are allotted, into n equal parts, and for terminating one cycle for a series of the process and/or computation predetermined within said one processing term,

PWM computing part 50 for computing each of PWM target values independently spending one or plural infinitesimal intervals and for computing PWM target value only according to control mode designated by said control input information during the present processing term, and

PWM commanding part 46 for receiving PWM target value computed on the processing term shortly previous to the present term as a PWM commanding value, and for outputting the PWM signals corresponding to said PWM commanding value every infinitesimal interval of present processing term.

35. Device for servo-controlling DC motor according to claim 34, wherein:

PWM target values output from PWM computing part 50 are limited to PWM maximum allowable value corresponding to the maximum allowable current of the motor or less.

36. Device for servo-controlling DC motor according to claim 34, wherein:

calculating part of PWM gradual values 452 for computing PWM gradual values for gradually getting close to a new PWM selection value by spending the succeeding several processing terms in the case that said new PWM selection value is different from the previous PWM selection value, and for outputting said PWM gradual values to PWM commanding part 46 as a PWM commanding value Pr<sub>−

SM</sub> is provided between said PWM computing part 50 and PWM commanding part 46 so as to output PWM signals which does not shock the motor.

37. Device for servo-controlling DC motor according to claim 34, wherein:

said PWM computing part 50 is provided with at least two computing parts out of computing part of PWM target value for position 441P, computing part of PWIVI target value for velocity 442V and computing part of PWM target for torque 443T.

38. Device for servo-controlling DC motor according to claim 34, wherein:

information input/output part 5 is provided for transmitting information between the PWM controlling means 4 and the superior controller 7, which has the receiving part 51 for receiving control input information including control target values and control modes from superior controller 7 in response to the instructions of said synchronizing control part 41 and for transferring said control input information to the proper storing part belong to said PWM computing part 50, individually.

39. Device for servo-controlling DC motor according to claim 34, wherein:

every information input/output part 5 having its own proper (ID) number 53 are connected by a serial communication line 61 with each other so that any of position, velocity or torque control for DC motor 2 equipped corresponding to individual information input/output part 5 may be instructed or charged (by said superior controller 7) through said serial communication line 61.

40. Device for servo-controlling DC motor according to claim 34, wherein:

said PWM controlling means 4 and information input/output part 5 are assembled into one chip of MPU, to which both positional signal Ea, Eb output from an encoder 1 and current signals output from an ammeter 31 are directly input and from which PWM signals are directly output to electric power supplier 3, 50 that the chip can directly communicate with said superior controller 7.

41. Device for servo-controlling DC, motor to claim 34, wherein:

said motor is a brushless-type DC motor 2N.