Aeronautics and astronautics – Spacecraft – With payload accommodation
Reexamination Certificate
1997-12-10
2001-05-22
Poon, Peter M. (Department: 3644)
Aeronautics and astronautics
Spacecraft
With payload accommodation
C244S165000, C244S158700
Reexamination Certificate
active
06234427
ABSTRACT:
BACKGROUND OF THE INVENTION
Satellites typically carry solar arrays that provide the power that the satellite requires to run its onboard systems. During eclipse periods however, the satellite draws energy from its batteries in order to provide power for the onboard systems. After the eclipse periods, when the solar array is once again exposed to light, the batteries are recharged using energy provided by the solar array. Thus, in the past, satellites have had to carry both solar arrays and batteries in order to provide energy to onboard systems.
The solar array and batteries also provide power to a mechanism which provides steering and pointing for the satellite. In the past, reaction wheels critically aligned with respect to three perpendicular axes have provided the steering and pointing functions. Rotating reaction wheels provide torques which depend in part on the speed and direction of rotation of the reaction wheel Known control laws are employed to adjust the reaction wheel speeds under the direction of, for example, a microprocessor, which is supplied power by the solar array and the batteries.
Batteries also require precise control over their charging profile in order to extend the battery life and thereby meet the satellite mission requirements. However, power generated by a solar array varies greatly from the beginning of life (BOL) of the solar array to the end of life (EOL) of the solar array. Because the batteries are charged with a fixed charge profile, power control circuitry must be included on each satellite to ensure that the power generated by the solar array is compatible with the charging voltage. For example, shunt regulators or series regulators are typically required to regulate power flow from the solar array and to provide the proper charging profile. In regulating the power flow from the solar array, shunt regulators simply dissipate excess current, typically through a resistor to ground. Therefore, although regulation is achieved, otherwise useful power is wasted. Series regulators, on the other hand, reduce available power to spacecraft loads due to internal losses in their circuitry.
Furthermore, reaction wheels, batteries, and the battery charge control circuitry take up a significant portion of the allocated satellite weight. Satellite batteries, in particular, are extremely heavy. As a result, a satellite cannot carry as much scientific, communications, or other equipment as it otherwise could. Furthermore, increased satellite weight also increases launch costs.
Therefore, a need remains for improved solar array regulation and satellite pointing which overcomes the disadvantages discussed above and previously experienced.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide solar array regulation and satellite pointing.
It is another object of the present invention to provide solar array regulation and satellite pointing that efficiently uses energy provided by a solar array.
Yet another object of the present invention is to provide energy storage, steering, and pointing for a satellite using flywheels.
Another object of the present invention is to substantially eliminate the batteries in a satellite.
Yet another object of the present invention is to reduce the size, weight, and cost of a satellite along with its associated launch costs.
Another object of the present invention is to reduce the size, weight, and cost of the energy storage and pointing systems of a satellite.
Another object of the present invention is to increase the amount of scientific, communications, and other equipment a satellite may carry.
The satellite power regulation and pointing system of the present invention includes a solar array connected to a power bus, at least first and second flywheels, and individual flywheel regulators connected to the first and second flywheels. The power bus carries the array voltage produced by the solar array. The first and second flywheels may be may be rotated at various speeds to increase or decrease the amount of kinetic rotational energy stored in the flywheels. In addition, the flywheel regulators include a power control circuit that determines when to store or to retrieve power from the flywheels. A flywheel motor/generator associated with each flywheel stores power in the rotating disk by a process that increases the rotational energy of the rotating disk and draws power from the rotating disk by a process that causes a reduction in the rotational energy of the rotating disk.
The flywheel regulator is connected to the power bus and to the flywheel motor/generator. As noted above, the flywheel regulator includes a power control circuit that allows power to flow to the flywheel motor/generator from the power bus, generally during energy storage periods and that allows power to flow to the power bus from the flywheel motor/generator, generally during energy drawing periods. The flywheel regulator further includes a feedback control loop connected to the power control circuitry and to the power bus. The feedback control loop determines the energy storage periods and the energy drawing periods by comparing a predetermined voltage reference with the power bus voltage. The energy storage periods generally correspond to periods of solar array light exposure, while the energy drawing periods generally correspond to periods of solar array eclipse conditions.
The flywheel regulator may also include a programmable voltage reference which substantially tracks the voltage produced by the solar array. Both the flywheel regulator and the loads may then operate on the appropriate solar array voltage from the beginning of life to the end of life of the solar array without wasting substantial amounts of power through a shunt regulator or series regulator.
REFERENCES:
patent: 4164018 (1979-08-01), Legrand
patent: 4188666 (1980-02-01), Legrand et al.
patent: 4272045 (1981-06-01), Phillips
patent: 4723735 (1988-02-01), Eisenhaure et al.
patent: 5261631 (1993-11-01), Bender et al.
patent: 5289998 (1994-03-01), Bingley et al.
patent: 5309082 (1994-05-01), Payne
patent: 5315158 (1994-05-01), Danielson
patent: 5500621 (1996-03-01), Katz et al.
patent: 5611505 (1997-03-01), Smay
patent: 0712781 (1996-05-01), None
patent: 712781 (1996-05-01), None
Pieronek, Thomas, J., Decker, D. Kent, Spector, Victor A.: “Spacecraft Flywheel Systems—Benefits and Issues,” Proceedings of the 1997 IEEE National Aerospace and Electronics Conference, vol. 2, Jul. 14-17, 1997, pp. 589-593, XP002096033, Dayton, OH, USA.
Ayer, Francois, Coco, Richard, Kelleher, William: “New Opportunities for Satellite Integrated Power and Attitude Control Systems,” Proceedings of the Annual Meeting—Institute of Navigation, Jun. 19-21, 1997, pp. 831-841, XP002096034, Cambridge, MA, USA.
Havenhill, Douglas D., Robinson, Wilf, Hanks, James, Gisler, Gary, Spina, Len, Ginter, Steve: “Spacecraft Energy Storage Systems,” Proceedings of the 1997 IEEE National Aerospace and Electronics Conference, vol. 2, Jul. 14-17, 1997, pp. 609-616, XP002096035.
Dinh Tien
Poon Peter M.
TRW Inc.
Yatsko Michael S.
LandOfFree
Solar array regulation and spacecraft pointing using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Solar array regulation and spacecraft pointing using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solar array regulation and spacecraft pointing using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2483450