Control magnetic bearing

• US 6,215,218 B1
• Filed: 04/08/1999
• Issued: 04/10/2001
• Est. Priority Date: 04/09/1998
• Status: Expired due to Fees

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Inventors: Ueyama, Hirochika
• Primary Examiner(s): TAMAI, KARL I
• Application Number:
  US09/288,039
• Time in Patent Office: 733 Days
• Field of Search: 310/90.5, 700/28, 700/30, 700/31, 700/32, 700/52
• US Class Current: 310/90.5
• CPC Class Codes: F16C 2231/00 Running-in; Initial operation
• CPC Class Codes: F16C 2360/45 Turbo-molecular pumps in general F04D19/04
• CPC Class Codes: F16C 32/0442 with devices affected by abnormal, undesired or non-standard conditions such as shock-load, power outage, start-up or touchdown
• CPC Class Codes: F16C 32/0455 including digital signal processing [DSP] and analog/digital conversion [A/D, D/A]
• CPC Class Codes: F16C 32/0489 with active support of five degrees of freedom, e.g. two radial magnetic bearings combined with an axial bearing

Abstract

A control magnetic bearing includes a mechanical main unit and a controller for controlling an excitation current supplied to electromagnets. The mechanical main unit comprises displacement sensors and magnetic bearing sets for supporting a rotor in a non-contacting manner. The controller is provided with a digital signal processor (DSP) which outputs a digital control signal for controlling the excitation current on the basis of a digital displacement signal. The DSP includes identification unit for identifying the type of the mechanical main unit. The identification unit identifies the type of the mechanical main unit on the basis of the response by the rotator.

Claims

1. A control magnetic bearing comprising:

a mechanical main unit;

a rotator coupled to said mechanical main unit;

a plurality of displacement sensors within said mechanical main unit for detecting displacement of said rotator;

a plurality of sets of magnetic bearings for supporting the rotator in a predetermined target position in a non-contacting manner using attractive magnetic forces generated by pairs of electromagnets, each pair of the electromagnets forming each set of the magnetic bearings; and

a controller having electromagnet control means for controlling an excitation current supplied to the electromagnets on the basis of signals output from the displacement sensors,

wherein the electromagnet control means has digital processing means which is programmable by software and outputs a digital control signal for controlling the excitation current on the basis of the digital displacement signal that is calculated from the signals output from the displacement sensors and that represents the displacement of the rotator, and

wherein the digital processing means has identification means for identifying the type of the mechanical main unit based on a response by said rotator.

2. The control magnetic bearing as defined in claim 1, wherein the identification means changes the target position after the rotator has been supported in the target position in a non-contacting manner, and, on the basis of the response by the rotator to the change in target position, the identification means identifiers the type of the mechanical main unit.

3. The control magnetic bearing as defined in claim 1, wherein the identification means changes the target position of the rotator by addition of a predetermined digital identification signal to the digital displacement signal, and calculates from the digital displacement signal the response by the rotator upon changing of the target position.

4. The control magnetic bearing as defined in claim 3, wherein the digital identification signal is a step waveform signal.

5. The control magnetic bearing as defined in claim 3, wherein the digital identification signal is a sinusoidal signal of constant frequency.

6. The control magnetic bearing as defined in claim 3, wherein the digital identification signal is a sinusoidal signal of variable frequency.

7. The control magnetic bearing as defined in claim 1, wherein after having supported the rotator in a predetermined target position in a non-contacting manner, the identification means excites the rotator and identifies the type of the mechanical main unit on the basis of the response by the rotator upon excitation.

8. The control magnetic bearing as defined in claim 7, wherein the identification means excites the rotator by addition of a predetermined digital identification signal to the digital control signal, and calculates from the digital displacement signal the response by the rotator upon excitation.

9. The control magnetic bearing as defined in claim 8, wherein the digital identification signal is a sinusoidal signal of constant frequency.

10. The control magnetic bearing as defined in claim 8, wherein the digital identification signal is a sinusoidal signal of variable frequency.

11. The control magnetic bearing as defined in claim 1, wherein the identification means identifies the type of the mechanical main unit on the basis of the response by the rotator when the rotator in a contact supported state—

in which the rotator is not supported by the magnetic bearing sets in a non-contacting manner—

is supported in a predetermined location by means of the magnetic bearing sets in a non-contacting manner.

12. The control magnetic bearing as defined in claim 11, wherein the identification means calculates the response by the rotator from the digital displacement signal when the rotator in the contact supported state is supported in a target position in a non-contacting manner.

13. The control magnetic bearing as defined in claim 1, wherein the identification means identifies the type of the mechanical main unit on the basis of an integral component of the digital control signal obtained when the rotator is supported in a target position by the magnetic bearing sets in a non-contacting manner.

14. A control magnetic bearing comprising:

a mechanical main unit;

a rotator coupled to said mechanical main unit;

a plurality of displacement sensors for detecting displacement of said rotator;

a plurality of sets of magnetic bearings for supporting the rotator in a predetermined target position in a non-contacting manner using attractive magnetic forces generated by pairs of electromagnets, each pair of the electromagnets forming each set of the magnetic bearings; and

a controller having electromagnet control means for controlling an excitation current supplied to the electromagnets on the basis of signals output from the displacement sensors,

wherein the electromagnet control means has a nonvolatile storage device and digital processing means which is programmable by software, and outputs a digital control signal for controlling the excitation current on the basis of the digital displacement signal that is calculated from the signals output from the displacement sensors and that represents the displacement of the rotator, the nonvolatile storage device stores control parameter for identification purposes and a plurality of sets of operation control parameters corresponding to the individual types of mechanical main units, and

wherein the digital processing means has identification means for identifying the type of the mechanical main unit and selecting the set of control parameters corresponding to the result of such identification from the nonvolatile storage device based on a response by said rotator.

15. The control magnetic bearing as defined in claim 14, wherein the identification means changes the target position through use of the control parameter sets for identification purposes after the rotator has been supported in the target position in a non-contacting manner, and, on the basis of the response by the rotator to the change in target position, the identification means identifies the type of the mechanical main unit.

16. The control magnetic bearing as defined in claim 15, wherein the identification means changes the target position of the rotator by addition of a predetermined digital identification signal to the digital displacement signal, and calculates from the digital displacement signal the response by the rotator upon changing of the target position.

17. The control magnetic bearing as defined in claim 16, wherein the digital identification signal is a step waveform signal.

18. The control magnetic bearing as defined in claim 16, wherein the digital identification signal is a sinusoidal signal of constant frequency.

19. The control magnetic bearing as defined in claim 16, wherein the digital identification signal is a sinusoidal signal of variable frequency.

20. The control magnetic bearing as defined in claim 14, wherein after having supported the rotator in a predetermined target position in a non-contacting manner through use of the control parameter set for identification purposes, the identification means excites the rotator and identifies the type of the mechanical main unit on the basis of the response by the rotator upon excitation.

21. The control magnetic bearing as defined in claim 20, wherein the identification means excites the rotator by addition of a predetermined digital identification signal to the digital control signal, and calculates from the digital displacement signal the response by the rotator upon excitation.

22. The control magnetic bearing as defined in claim 21, wherein the digital identification signal is a sinusoidal signal of constant frequency.

23. The control magnetic bearing as defined in claim 21, wherein the digital identification signal is a sinusoidal signal of variable frequency.

24. The control magnetic bearing as defined in claim 14, wherein the identification means identifies the type of the mechanical main unit on the basis of the response by the rotator when the rotator in a contact supported state—

in which the rotator is not supported by the magnetic bearing sets in a non-contacting manner—

is supported in a predetermined location through use of the control parameter set for identification purposes by means of the magnetic bearing sets in a non-contacting manner.

25. The control magnetic bearing as defined in claim 24, wherein the identification means calculates the response by the rotator from the digital displacement signal when the rotator in the contact supported state is supported in a target position in a non-contacting manner.

26. The control magnetic bearing as defined in claim 14, wherein the identification means identifies the type of the mechanical main unit on the basis of an integral component of the digital control signal obtained when the rotator is supported in a target position by the magnetic bearing sets in a non-contacting manner through use of the control parameter set for identification purposes.