Drive circuit for brushless DC motors

• US 5,717,297 A
• Filed: 06/05/1995
• Issued: 02/10/1998
• Est. Priority Date: 10/03/1991
• Status: Expired due to Term

• Current Assignee: Papst Licensing GmbH & Company Kg
• Original Assignee: Papst Licensing GmbH & Company Kg
• Inventors: Karwath, Arno, Wunsch, Eberhard, Moini, Mojtaba
• Primary Examiner(s): Masih, Karen
• Application Number:
  US08/465,138
• Time in Patent Office: 981 Days
• Field of Search: 318/254, 318/439, 318/138, 388/907.5
• US Class Current: 318/400.14
• CPC Class Codes: H02P 6/06 Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: H02P 6/17 and for generating speed information
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

A drive circuit for brushless DC motors comprising a rotor and a stator with at least one stator coil includes a commutation device which supplies commutation pulses of drive current to the stator coil(s). The commutation device senses the rotor position and calculates current rotor speed therefrom. The rotor speed is then used to shift the commutation currents according to predetermined functions. The shifting of commutation currents is occasioned by shifting either or both of the ignition part of a commutation pulse and the extinction part of such pulses.

Claims

1. A drive circuit for a brushless DC motor with a rotor and a stator housing at least one stator coil, said drive circuit comprising:

first apparatus for measuring angular position of the rotor relative to the stator and for determining motor speed;

commutator means for connecting and interrupting current to the stator coil at specified moments of commutation determined from the angular rotor position relative to the stator; and

a commutation shifting apparatus for shifting the specified moments of commutation, the amount of shifting being a predetermined function of motor speed.

2. A drive circuit according to claim 1, characterized in that the commutation shifting apparatus pre-displaces the moments of commutation by a specified, first electrical preignition angle with respect to the rotational position of the rotor, upon initial start-up of the rotor.

3. A drive circuit according to claim 1, characterized in that the commutation shifting apparatus pre-displaces the moments of commutation increasingly toward the rotational position or the rotor after a specified motor speed has been exceeded.

4. A drive circuit according to claim 1, characterized in that the commutation shifting apparatus shifts the moment for turn-on of a motor current that is allocated to one commutation phase.

5. A drive circuit according to claim 1, characterized in that the commutation shifting apparatus shifts the moment for turn-off of a motor current that is allocated to one commutation phase.

6. A drive circuit according to claim 1, characterized in that the drive circuit comprises a microprocessor controller.

7. A drive circuit according to claim 1, comprising a speed control device.

8. A drive circuit in accordance with claim 1 wherein the first apparatus comprises means for measuring motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of measured motor speed.

9. A drive circuit according to claim 8, characterized in that the commutation shifting apparatus pre-displaces the moments of commutation relative to the rotational position of the rotor, as a function of the estimated motor speed.

10. A drive circuit in accordance with claim 1 wherein the first apparatus comprises means for estimating motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of estimated motor speed.

11. A drive circuit for a brushless DC motor with a rotor and a stator housing at least one stator coil, said drive circuit comprising:

first apparatus for measuring angular position of the rotor relative to the stator and for determining motor speed;

commutator means for connecting and interrupting current to the stator coil at specified moments of commutation determined from the angular rotor position relative to the stator; and

a commutation shifting apparatus for shifting the specified moments of commutation, the amount of shifting being a predetermined function of motor speed, wherein the moments of commutation are shifted as a function of the motor speed according to an unsteady function.

12. A drive circuit according to claim 11, wherein the commutation shifting apparatus pre-displaces the moments of commutation by a specified, first electrical preignition angle with respect to the rotational position of the rotor, upon initial start-up of the rotor.

13. A drive circuit according to claim 11, wherein the commutation shifting apparatus pre-displaces the moments of commutation increasingly toward the rotational position of the rotor after a specified motor speed has been exceeded.

14. A drive circuit according to claim 11, wherein the commutation shifting apparatus shifts the moment for turn-on of a motor current that is allocated to one commutation phase.

15. A drive circuit according to claim 11, wherein the commutation shifting apparatus shifts the moment for turn-off of a motor current that is allocated to one commutation phase.

16. A drive circuit according to claim 11 wherein the drive circuit comprises a microprocessor controller.

17. A drive circuit according to claim 11 comprising a speed control device.

18. A drive circuit in accordance with claim 11, wherein the first apparatus comprises means for measuring motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of measured motor speed.

19. A drive circuit according to claim 11, wherein the commutation shifting apparatus pre-displaces the moments of commutation relative to the rotational position of the rotor, as a function of the estimated motor speed.

20. A drive circuit according to claim 11, wherein the first apparatus comprises means for estimating motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of estimated motor speed.

21. A drive circuit for a brushless DC motor with a rotor and a stator housing at least one stator coil, said drive circuit comprising:

first apparatus for measuring angular position of the rotor relative to the stator and for determining motor speed;

commutator means for connecting and interrupting current to the stator coil at specified moments of commutation determined from the angular rotor position relative to the stator; and

a commutation shifting apparatus for shifting the specified moments of commutation, the amount of shifting being a predetermined function of motor speed, wherein the moments of commutation are shifted as a function of the motor speed according to a piece-wise linear function.

22. A drive circuit according to claim 21, wherein the commutation shifting apparatus pre-displaces the moments of commutation by a specified, first electrical preignition angle with respect to the rotational position of the rotor, upon initial start-up of the rotor.

23. A drive circuit according to claim 21, wherein the commutation shifting apparatus pre-displaces the moments of commutation increasingly toward the rotational position or the rotor after a specified motor speed has been exceeded.

24. A drive circuit according to claim 21, wherein the commutation shifting apparatus shifts the moment for turn-on of a motor current that is allocated to one commutation phase.

25. A drive circuit according to claim 21, wherein the commutation shifting apparatus shifts the moment for turn-off of a motor current that is allocated to one commutation phase.

26. A drive circuit according to claim 21, wherein the drive circuit comprises a microprocessor controller.

27. A drive circuit according to claim 21, comprising a speed control device.

28. A drive circuit in accordance with claim 21, wherein the first apparatus comprises means for measuring motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of measured motor speed.

29. A drive circuit according to claim 21, wherein the commutation shifting apparatus pre-displaces the moments of commutation relative to the rotational position of the rotor, as a function of the estimated motor speed.

30. A drive circuit in accordance with claim 21, wherein the first apparatus comprises means for estimating motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of estimated motor speed.