Drive circuit for brushless DC motors

• US 6,384,554 B1
• Filed: 02/10/1998
• Issued: 05/07/2002
• Est. Priority Date: 10/03/1991
• Status: Expired due to Fees

• Current Assignee: Papst Licensing GmbH & Company Kg
• Original Assignee: Papst Licensing GmbH & Company Kg
• Inventors: Moini, Mojtaba, Karwath, Arno, Wünsch, Eberhard
• Primary Examiner(s): Fletcher, Marlon T.
• Assistant Examiner(s): Duda, Rina I.
• Application Number:
  US09/021,207
• Time in Patent Office: 1,547 Days
• Field of Search: 318/138, 318/439, 318/254
• 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 including a rotor and a stator with at least one stator coil includes a commutation device which supplied commutation pulses of drive current to the state 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 circuits according to predetermined functions. The shifting of commutation currents is occasioned by shifting either or both of ignition part of a commutation pulse and the extinction part of such pulse.

Claims

1. An assembly comprising:

a load member; and

a brushless DC motor, comprising;

a rotor coupled to said load member;

a stator housing at least one stator coil; and

a drive circuit comprising;

a rotor position measurement circuit for measuring angular position of the rotor relative to the stator and for determining motor speed;

a commutator circuit 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. The assembly of claim 1, wherein the commutation shifting apparatus, responsive to initial start-up, pre-displaces the moments of commutation by a specified, first electrical preignition angle with respect to the rotational position of the rotor.

3. The assembly of claim 1, wherein the commutation shifting apparatus pre-displaced the moments of commutation increasingly toward the rotational position of the rotor after a specified motor speed has been exceeded.

4. The assembly of claim 1, wherein the commutation shifting apparatus shifts the moment for turn-on of a motor current that is allocated to one commutation phase.

5. The assembly of claim 1, wherein the commutation shifting apparatus shifts the moment for turn-on of a motor current that is allocated to one commutation phase.

6. The assembly of claim 1, wherein the drive circuit further comprises a microprocessor controller.

7. The assembly of claim 1, wherein the drive circuit further comprises a speed control circuit.

8. The assembly of claim 1, wherein the rotor position measuring circuit comprises a circuit for measuring motor speed and wherein the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of measured motor speed.

9. The assembly of claim 8, wherein the commutation shifting apparatus pre-displaces the moments of commutation relative to the rotational position of the rotor, as a function of an estimated motor speed.

10. The assembly of claim 1, wherein the rotor position measuring circuit comprises a circuit 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. An assembly comprising:

a load member; and

a brushless DC motor, comprising;

a rotor coupled to said load member;

a stator housing at least one stator coil; and

a drive circuit comprising;

a rotor position measurement circuit for measuring angular position of the rotor relative to the stator and for determining motor speed;

a commutator circuit 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. The assembly of claim 11, wherein the commutation shifting apparatus, responsive to initial start-up, pre-displaces the moments of a commutation by a specified, first electrical preignition angle with respect to the rotational position of the rotor.

13. The assembly of claim 11, wherein the commutation shifting apparatus pre-displaced the moments of commutation increasingly toward the rotational position of the rotor after a specified motor speed has been exceeded.

14. The assembly of 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. The assembly of 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. The assembly of claim 11, wherein the drive circuit further comprises a microprocessor controller.

17. The assembly of claim 11, wherein the drive circuit further comprises a speed control circuit.

18. The assembly of claim 12, wherein the first apparatus comprises a circuit for measuring motor speed and wherein the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of measured motor speed.

19. The assembly of claim 18, wherein the commutation shifting apparatus pre-displaces the moments of commutation relative to the rotational position of the rotor, as a function of an estimated motor speed.

20. The assembly of claim 11, wherein the rotor position measuring circuit comprises a circuit 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. An assembly comprising:

a load member; and

a brushless DC motor, comprising;

a rotor coupled to said load member;

a stator housing at least one stator coil; and

a drive circuit comprising;

a rotor position measuring circuit for measuring angular position of the rotor relative to the stator and for determining motor speed;

a commutator circuit 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. The assembly of claim 21, wherein the commutation shifting apparatus, responsive to initial start-up, pre-displaces the moments of commutation by a specified, first electrical preignition angle with respect to the rotational position of the rotor.

23. The assembly of claim 21, 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.

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

25. The assembly of 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. The assembly of claim 21, wherein the drive circuit further comprises a microprocessor controller.

27. The assembly of claim 21, wherein the drive circuit further comprises a speed control circuit.

28. The assembly of claim 21, wherein the first apparatus comprises a circuit for measuring motor speed and wherein the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of measured motor speed.

29. The assembly of claim 28, wherein the commutation shifting apparatus pre-displaces the moments of commutation relative to the rotational position of the rotor, as a function of an estimated motor speed.

30. The assembly of claim 21, wherein the rotor position measuring circuit comprises a circuit for estimating motor speed and the amount of commutation moment shifting by the commutation shifting apparatus is a predetermined function of estimated motor speed.

31. A drive circuit for a brushless direct- current motor having a rotor and a stator, the stator having a stator winding, comprising:

a commutation device that delivers or interrupts current to a stator winding in a positive or negative direction depending upon a rotor rotation angle; and

a circuit for measuring motor speed, the motor speed measuring circuit providing for a revolution-dependent forward displacement of switching off of the current, for a commutation phase.