Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1990-12-06
1992-10-13
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
318629, H02K 709, F16C 3906
Patent
active
051554020
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a bearing for the radial and axial support of a rotor having large radial dimensions about a stator.
DE-OS 3,243,641 discloses that mechanical bearings, and electrodynamic magnetic bearings can be employed for rotors having large radial dimensions.
This publication also discloses the control of the tilt axes of a rotor having large radial dimensions in order to, on the one hand, effectively counteract interfering moments and natural frequencies and, on the other hand, generate certain moments which, in the manner of gyroscopic moments, cause the system to swing horizontally.
DE-OS 3,240,809 discloses a magnetic bearing in which the diameter of the air gap is large compared to the axial length of the bearing. The rotor is radially passively mounted by means of permanent magnets at least on the side of the rotor, while the axial position of the rotor is actively regulated by a control device. In order to determine the axial position of the rotor, several sensor arrangements are employed as well as control amplifiers and coils which exert forces on the rotor. Four sensor arrangements are arranged in pairs diametrally to the axis of rotation on mutually perpendicular axes which are also perpendicular to the axis of rotation. Three control amplifiers are provided of which the first and second control amplifier each receive the difference between the sensor signals of diametrally opposite sensor arrangements and the third control amplifier receives the sum of all sensor output signals. The outputs of the control amplifiers are connected with windings in such a manner that actuation of the first and second amplifier causes restoring moments to act on the rotor about the axis perpendicular to the axis on which the associated sensor arrangements are disposed and actuation of the third amplifier causes an axial restoring force to act on the rotor.
Additionally the '809 reference discloses that the input signals of the first and second control amplifier are cross-coupled, that is, part of the input signal of the one amplifier is superposed on the input signal of the other amplifier.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a control method and a magnetic bearing for the radial and axial support of rotors having large radial dimensions and operating over a broad range of revolutions while also being usable without problems for so-called "micro-g" environments.
This is accomplished by the the bearing for stabilizing a rotor about tilt axes of a stator according to the invention. This bearing includes sensing means, associated with the X and Y axes of the stator, for determining angles of tilt of the rotor with respect to the stator's axes and for outputting signals representing the determined tilt angles; control coils disposed on the stator and associated with the X and Y axes of the stator; and control means, connected to the outputs of the sensing means, for generating control currents in the control coils so a to generate, in connection with magnets disposed on the rotor, moments which act on the rotor influencing the determined tilt angles. The control means of the invention employs controllers which receive the determined tilt angles, and and alternating coupling means connected to the output of the controllers for cancelling the coupling of the X and Y tilt axes of the rotor caused by gyroscopic effects. The alternating coupling means has integral characteristics with time constants which are inversely proportional to the number of revolutions of the rotor.
Advantages of this invention reside in the possibility of actively and horizontally swinging the tilt axes in order to generate, without further expense, torques in the second tilt axis. The second tilt axis is perpendicular to the axis of rotation and to the actively pivoted tilt axis. The torques are generated simply by the control principle employed. Another advantage is in the use of the bearing for rotors having a low height.
Other aspects of the invention in connection
REFERENCES:
patent: 3955858 (1976-05-01), Poubeau
patent: 4040508 (1977-08-01), Sunada et al.
patent: 4121143 (1978-10-01), Habermann et al.
patent: 4143312 (1979-03-01), Duckworth et al.
patent: 4294493 (1981-10-01), Sindlinger et al.
patent: 4392693 (1983-07-01), Habermann et al.
patent: 4839550 (1989-06-01), Mizuno et al.
Klimek, Deutsche Luft-und Raumfahrt, Inst. fur Flugfuhrung, Mar. 1972, 141 pp. + appendises: "Ein Beitrag Zur messtechischen Anwendung der aktiven elektromagnetischen Lagerung".
Rebsch D. L.
Stephan Steven L.
Teldix GmbH
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