Electricity: motive power systems – Positional servo systems
Reexamination Certificate
1999-09-03
2001-11-27
Ip, Paul (Department: 2837)
Electricity: motive power systems
Positional servo systems
C318S601000, C318S618000, C318S611000, C318S621000
Reexamination Certificate
active
06323614
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to the field of control systems and more particularly to a system and method for controlling suspension using a magnetic field.
BACKGROUND OF THE INVENTION
Flywheels are energy storage devices competitive with electrochemical batteries. Their advantage is greatly increased when they are suspended magnetically without physical contact with machinery housing, as is typical with rolling element or fluid film bearings. Magnetic suspension greatly decreases power losses due to bearing drag torque in comparison with rolling element or fluid film bearings. Many applications of flywheels require compact size and low weight, while maintaining a high level of stored energy. One difficulty experienced with employing magnetic suspension with flywheels, as well as many other applications, is the instability of a control system when confronted with a member or shaft that rotates at high speeds.
In addition to the particular application of flywheels, there is a need for stable magnetic suspension systems in many applications utilizing high speed rotating shafts or other members. For example, momentum wheels are an important and effective means of controlling the attitude of orbital satellites. Similar problems are also experienced with turbo compressors for air conditioning units utilized on aircraft and in other high performance vehicles. Turbomolecular vacuum pumps are another example of an application that would benefit from a stable magnetic suspension system for high speed rotating shafts. Many other applications may also benefit from the development of a stable magnetic suspension system that may be used to control rotating machinery for industrial and military applications. The instability of such magnetic suspension systems for high speed applications inherently limit such development.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system and method for controlling suspension using a magnetic field are disclosed that address disadvantages and problems associated with previous control methods and systems.
In one embodiment of the present invention, a system for controlling the position of a rotating member suspended using a magnetic field includes at least one sensor that is operable to detect the position of the rotating member. The sensor is further operable to generate a position reference signal in response to the detected position. The system also includes a controller in communication with the at least one sensor. The controller is also operable to generate an actuator control signal in response to receiving the position reference signal. The controller is further operable to introduce a phase lead in the actuator control signal in response to a rotational speed of the rotating member. The system further includes at least one actuator in communication with the controller. The actuator is operable to adjust the position of the rotating member in response to the actuator control signal by modifying characteristics of the magnetic field.
In another embodiment of the present invention, a method of controlling the position of a rotating member suspended using a magnetic field includes generating a position reference signal in response to a detected position of the rotating member. The method also determines an actuator control signal in response to the position reference signal. The actuator control signal includes a phase lead introduced in response to a rotational speed of the rotating member. The method adjusts the position of the rotating member in response to the actuator control signal by modifying characteristics of the magnetic field.
In yet another embodiment of the present invention, a system for controlling the position of a rotating member suspended using a magnetic field includes at least one sensor that is operable to detect the position of the rotating member. The sensor is further operable to generate a position reference signal in response to the detected position. The system also includes a summer in communication with the at least one sensor and being operable to compare the position reference signal to a targeted position value. The system further includes control logic in communication with the summer. The control logic is operable to generate a control output signal in response to the compared position reference signal and targeted position value. The system also includes at least one gain compensator in communication with the control logic. The gain compensator is operable to introduce gain in the control output signal. The system additionally includes at least one lead compensator in communication with the gain compensator. The lead compensator is operable to introduce phase lead in the control output signal. The system further includes at least one actuator responsive to the lead compensator that is operable to adjust the position of the rotating member in response to the control output signal by modifying characteristics of the magnetic field.
REFERENCES:
patent: 3974699 (1976-08-01), Morris et al.
patent: 4228396 (1980-10-01), Palombo et al.
patent: 4295171 (1981-10-01), Hirota et al.
patent: 4575666 (1986-03-01), Nakashima et al.
patent: 4633423 (1986-12-01), Bailey
patent: 4686404 (1987-08-01), Nakazeki et al.
patent: 4712853 (1987-12-01), Howard
patent: 4999534 (1991-03-01), Andrianos
patent: 5107192 (1992-04-01), Kirchberg et al.
patent: 5126641 (1992-06-01), Putman et al.
patent: 5256952 (1993-10-01), Yoneyama et al.
patent: 5304907 (1994-04-01), Abe et al.
patent: 5329216 (1994-07-01), Hasegawa et al.
patent: 5708312 (1998-01-01), Rosen et al.
patent: 5736802 (1998-04-01), Ueyama et al.
patent: 5783924 (1998-07-01), Kahlman
patent: 5838123 (1998-11-01), Zhao
patent: 5998899 (1999-12-01), Rosen et al.
patent: 59-151619 (1984-08-01), None
Kirk, J., et al; “Performance of a Magnetically Suspended Flywheel Energy Storage System;”, Dec. 1995.
Okada, Y., et al.; “Cross Feedback Stablization of the Digitally Controlled Magnetic Bearing;” Journal of Vibration and Acoustics, vol. 114, pp. 54-59, Jan. 1992.
Bichler, U. J.; “A Low Noise Magnetic Bearing Wheel for Space Application;” 2ndInternational Symposium on Magnetic Bearings, Tokyo, Japan; pp. 1-8, Jul. 12-14, 1990.
Cheol-Soon Kim, et al.; “In-situ Runout Indentification in Active Magnetic Bearing System by Extended Influence Coefficient Method;” Fifth International Symposium on Magnetic Bearings; all, Aug. 1996.
Kondoleon, A. S., et al.; “Magnetic Bearings at Draper Laboratory ,” Proceedings of MAG '95, Technomic Pub.,; pp. 197-206.
Pang, D.-C.; “Power Losses in Magnetic Bearing System for Flywheel Energy Storage;” Proceedings of MAG '95; Technomic Pub., pp. 353-362.
Abrens, M., et al.; “Cross Feedback Control of a Magnetic Bearing System;” pp. 177-191, No Date.
Ahrens, M., et al.; “Performance of a Magnetically Suspended Flywheel Energy Storage Device;” IEEE Transactions on Control Systems Technology, vol. 4; pp. 494-502, Sep. 1996.
Ahrens, M., et al.; “Design of a Magnetically Suspended Flywheel Energy Storage Device;” Fourth International Symposium on Magnetic Bearings, pp. 553-558, Aug. 1994.
Murakami, C.; “A Design Method of a Dynamic Compensator of Conical Modes For Magnetic Bearings of a Rigid Spinning Rotor,” 2ndInternational Symposium on Magnetic Bearings, Tokyo, Japan; pp. 307-310, Jul. 12-14, 1990.
Bornemann, H., et al.; “A Flywheel for Energy Storage With Frictionless High Temperature Superconductor Bearings;” Fourth International Symposium on Magnetic Bearings, ETH Zurich, pp. 543-545, Aug. 1994.
Jayaraman, C. P., et al; “Rotor Dynamics of Flywheel Energy Storage Systems;” Journal of Solar Energy Engineering, vol. 113, pp. 11-18, Feb. 1991.
Wells, S., et al.; “Manufacturing and Testing of a Magnetically Suspended Composite Flywheel Energy Storage System;” Third International Conference on Magnetic Suspension System, pp. 543-550, No Date.
Ahrens, M., et al.; “Field Experiences With a Highly Unbalanced Magnetically Suspended Flywheel Rotor,” 5th International Symposium on Magnetic Bearings, Japa
Li Mu
Na Uhn Joo
Palazzolo Alan
Thomas Erwin
Baker & Botts L.L.P.
Ip Paul
The Texas A&M University System
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