Several of the issues of the workshop are addressed from the perspective of a potential Space Station developer and energy wheel user. Systems' considerations are emphasized rather than component technology. The potential of energy storage wheel (ESW) concept is discussed. The current status of the technology base is described. Justification for advanced technology development is also discussed. The study concludes that energy storage in wheels is an attractive concept for immediate technology development and future Space Station application

Oglevie, R. E.

English

NASA Technical Reports Server

I_85
PERSPECTIVES ON ENERGY STORAGE WHEELS
FOR SPACE STATION APPLICATION
13860
D_io
Rouald E. OElevie
Rockwell International
Shuttle InteEration &
Satellite Systems Division
Downey, California
117
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https://ntrs.nasa.gov/search.jsp?R=19850005551 2020-03-22T17:36:35+00:00Z
OVERVI_
The purpose of this paper is to address several of the issues of the workshop
from the perspective of a potential Space Station developer and energy wheel user.
Systems' considerations are emphasized rather than component technology. The
issues of concern are: What is the potential of energy storage wheel (ESW) con-
cepts? What is the current status of the technology Base? Does justification
exist for advanced technology development? How should such a technology program
be defined? .... etc.
Fig. 1 illustrates the logic flow of the presentation. The study concludes
that energy storage in wheels is an attractive concert for immediate technology
development and future Space Station application.
• THE IPACS LEGACY
• TECHNOLOGY ADVANCE IN LAST DECADE
• HOW DO ESWs STACK UP FOR SPACE STATION?
• A SYSTEMS POINT OF VIEW
• TECHNOLOGY ISSUES
'_ CONCLUSIONS & RECOMMENDATIONS
Figure 1
118
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SUMMARY OF XPACS FEASIBILITY WORK (1970)
The Integrated Power and Attitude Control System (IPACS) work was performed
by the NASA Langley Research Center and its contractor, Rockwell International
(see refs. i, 2, and 3). This effort provides a valuable legacy of information
for several reasons. In terns of scope, it is the most comprehensive treatment
of the application of ESW's to spacecraft at this time despite being approxi-
mately i0 years old. It treats syst_ns as wel! as cumponent-level issues on a
rational and consistent basis.
A brief sugary of the work and the related conclusions are given in Fig. 2.
A much more Comprehensive su_ma_] is given in ref. i. In general, the majo: con-
clusions of the study are still valid _oday.
• ROTATING ASSEMBLY EMPLOYING TITANIUM ROTOR DEVELOPED &
SUCCESSFULLY TESTED
• MODIFIED CONSTANT STRESS ROTOR SHAPE UTILIZED
• TECHNICAL FEASIBILITY, PERFORMANCE & COST ADVANTAGES ESTABLISHED• MOST APPLICABLE TO SPACECRAFT WITH LARGER ENERGY & MOMENTUMSTORAGE REQUIREMENTS & LONG LIFE
• DESIGN CONCEPTS DEVELOPED FOR A VARIETY OF SPACE APPLICATIONS
• (MODULAR SPACE STATION, TDRS, EARTH OBSERVATION SPACECRAFT, RESEARCH &
APPLICATIONS MODULE, ll_JS PLANETARY SPACECRAFT, & EXTENDED-OURATION
ORBITER)
• COST & WEIGHT ADVANTAGES FOR MOST MISSIONS
• TYPICAL ENERGY DENSITIES APPROXIMATELY TWICE THAT OF NiCd
BATTERIES
• ADVANTAGES INCREASE WITH NUMBER OF CHARGE/DISCHARGE CYCLES
• READILY ADAPTABLE TO GIMBALED & NONGIMBALED APPLICATIONS
• SUBSTANTIAL PERFORMANCE IMPROVEMENT SHOWN WITH CONSERVATIVE
TECHNOtOGY ADVANCES
• DYNAMIC SIMULATION OF SIMULTANEOUS ENERGY MANAGEMENT & ATTITUDE
CONTROL, NO SIGNIFICANT PERFORMANCE OR DYNAMIC INTERACTION
PROBLEMS
• DETAILED DESIGN APPROACH ESTABLISHED
_m
Figure 2
119
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I'PACS DESIGN CONCEPT
(RA_ 1970's TECHNOLOGY)
Fig. 3 illustrates the _PACS design concept considered to be state-of-the-art
technology in the early 1970's. The laboratory tpst model employed a high-strenEth-
to-weigh_ titanitm alloy rotor and ball bea_ings with thln-film lubrication for low
losses. The rotor design was a modified constant stress shape. Other parameters
include :
• Component weight: 173 ib
• Rated angular momentum: 1075 ft-lb-sec
• Rated power dellve.--y : 2.5 kW
• Rat:ed energy storage: I.i kWh
• Operating speed range: 17,500 to 35,000 rpm
¢Ir " _.
M _ U_RU P XVACOUM PU P /\ X_/
VALVE %. HOUSING _ V
120
Figure 3
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• Q
TECHNOLOGY ADVANCES SUPPORTING _ACE APPLICATXONS OF ESW's
(LAST DECADE)
During the last decade, appreciable advances have occurred in the three basic
technology areas which form the constituent parts of an advanced ESW Syst_,
(Fig. 4). Tmprovements in permaneut magnets, design of the magnetic elements, and
advancements in power processing and control circuitry have given rise to improved
energy recovery efficlencles. These have gone from the 60Z range to a potential
value over 90Z under certain ideal conditions. Ref. 4 presents favorable test
data approaching this range.
The ma&uetic bearing technology has seen many more laboratory and operational
system developments and tests. Although the specific magnetic bearing design con-
cept most appropriate to ESW application may not have been selected yet, the
general technology is sufficient for incorporation in ESW space applications. The
potential merits of very low friction, controlled rotor dynamics, and a maintenance-
free, lonE-llfe rotor system are sufficient to suggest leap-frogging past the use
of ball-bearlng technology along with the attendant lifetime and maintenance con-
cerns. The magnetic bearings are the Crucial element in achieving a 20-year
lifetime without rotor servicing and maintenance. The long-llfe potential of
ESW's may well prove to he their single biggest cost advantage relative to regen-
erative fuel cell and battery systems which require much more frequent chanEeout
(order of five years) and even more frequent servicing.
The composite rotor technolo@y is the key to achievins higher energy densi-
ties, and the recent DOE energy wheel development testinS progr =m (see ref. 5)
provides a valuable legacy in this area. If historical precedent has meaning,
the advances in composite system stress-hearln E properties are increasing at a
rate that exceeds the energy density improv_-ents seen _n secondary battery sys-
t_as over the last 15 years. Extrapolation suggests that future improvement in
composite rotor eQergy density will advance faster than that of batteries.
There are many agencies and firms beyond those named in figure 4 who have
provided strong contributions to the ES_ technology base, and the author apolo-
gizes for these omissions.
It is concluded that the three basic technology building blocks in figure 4
are adequately developed to support the ESW technology advancement. The next most
importan£ technology prosram step is to define how best to integrate these three
areas into a highly efficient ESW System ann provide laboratory verification of
the performance. Improvements in the three technology areas should also be
supported since further advances seem quite feaslhle.
121
.TECHNOLOGY ITEM
I CONCLUSIONS
FACTOR ADVANCEMENTS
HIGH CHARGE/
DISCHARGE
CYCLE
EFFICIENCY
• IMPRQVIE9PERMANENTMAGNETS
• MOSFIETCIRCUITRY
• IMPROVEDMAGNETICDESIGN
• VERYLOWFRICTION
• VIBRATION
ISOLATION
• RELIABILITY
• RUSSIANS HAVEFLOWNTHEM
(CLASSIFIED PROGRAM)
AFML REACTIONWHEELTESTS
NASA LaRCTESTS OF AMCD
EUROPEANDEVELOPMENTS
• MANY OTHERS
I
• HIGHERENERGY I
DENSITIES I* SAFETY
• DOEPROGIIAM(S)
• CHARGE/DISCHARGE EFFICIENCY MUCH IMPROVED -- (0.66 TO 0.85+)
• lAB VERIFICATION OF THREE BASIC TECHNOLOGY AREAS
Figure 4
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122
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ELECTRICAL POWER SYST_4 MASS FOE VARIOUS
STORAGE COMPONENT EFFICIENCIES & ENERGY DENSITIES
The curves and data points shown in FiE. 5 present estimates of the electrical
power system (EPS) mass for several parameter variations and for three potential
energy storage component types. The data show a distinct advantage for the ES_
System. Of course, it is recognized that relatively few test data exist for this
type of system, and its predicted performance is more uncertain.
In addition to EPS mass, the storage component energy recovery efficiency has
a significant impact on other subsystems, such as the extra thermal control systM
capacity needed to reject the heat dissipated in the storage element, and propel-
lant required to overcome the drag due to solar array size increases. The ESW
System has a clear-cut advantage in these two areas. Of course, the most notable
mass saving is in the attitude control system. The control moment gyro mass sav-
ings, by integratin E the attitude control function with the ESW System, is in
excess of 1.8 megaEr_-ns for a typical Space Station.
Over the 20-year Space Station life cycle, relatively large mass saviags also
accrue for the ESW System due to its potential 20-year llfe. The competing systems
typically require changeout at much more frequent intervals as previously noted.
It is concluded that appreciable system mass savings beyond the energy stor-
age element itself can result from its higher energy recovery efficiency. Although
formal costing has not been done, these results tend to indicate a possible cost
saving.
• 75 kVJCONnl4UOUSBUSP0VER
• EFRCIIUiT(I_GH If0LTAllk')TRRMSMI,S_d0NSYSTEM
• SOLARItqllA¥ P0WB 01EN$1TY--41WlkO
(6aks. LOWC0NCBrmAI10NMTI0)
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0.5 11'.6 8.7 $.8 0'A !.0
STORAGEC01m'911BTIMBSY I_COTBY
Figure 5
12:)
-. ._
MOMENTUM BUILDUP FEQM VARIOUS SOURCES
Fig. 6 provides data for typical sfz_E of Space Station control moment gyros
(CMG's) and for a varlery of conditions and s_tuatlons. Normal CHG sizing of
about 20,000 ft-lb-sec (approximateiy 4000 ib weight) is possible. This is
achieved by flying in constrained (low disturbance torque) ,zlentat£ons and by
performing the infrequent operations requirlnE large angular moment_ _rlth reac-
tion control thrusters. Use of the Integrated Power and Attitude Control Syste_
(IPACS) approach can save most of this _G weight and cost. _n addition, the ESW's
produce an excess of angular moment,-, which w_ll enable more robust operation than
is possible with Q4G's. Ref. 6 presents additional data and rationale as to why
the _IG sizing can become much larger in the absence of prudent attitude constraints,
payload operations _ and momenta management techniques.
ITEM
GRAV GRAD
TORQUE:
• LVLH
AI_'ITUDE
• LVLH
ATTITUDE
• LVLH
ATTITUDE
• INERTIAL
AI"I'ITUDE
AERODYNAMIC
TORQUE
DYNAMIC
PAYLOAD
OPERATIONS
ATTITUDE
MANEUVERING
CREW
DISTURBANCE
DOCKING
DISTURBANCE
BASIS
PRINCIPAL AXES _. lO
FROM LVLH
BODY AXES ALIGNED
TO LVLH
WORST CASE PRINCIPAL
AXES ORIENTATION
PRINCIPAL AXIS _ lO
FROM POP
90-day ORBIT DECAY,
CP.CG = 10 ft
LARGE PAYLOAD
MOVED WITHIN
1 ORBIT PERIOD
MINIMUM SLEW RATE =
4olmin (90 ° IN
QUARTER ORBIT)
200 lb PUSHOFF IN
WORST LOCATION
CLOSURE VELOCITY =
0.5 fllse¢
MOMENTUM BUILDUP" (lt-lb-sec)
WITH ORBITER wITHouT ORBITER
8,470 2,250
200,000 12,000
243,000 64,500
18,800 5,120
-- 10,700
2,0O0 2,OO0
22,6OO
64,900
4,000
8,000
81,110
"MOMENTUM STORAGE CAPACITY REQUIRED IF CONTROLLED WITH
MOMENTUM STORAGE DEVICES, SECULAR COMPONENTS BASED ON
BUILDUP OVER ONE ORBIT
I 124
v
Figure 6
SOME ENERGY STORAGE WHEEL (ESW) SYSTEM DESIGN ISSUES
FIg. 7 presents a series of design issues related co the Space Station appli-
cation and should be siren conslderatlo_ In ESW technology development programs.
Many of the earlier design concepts from previous studies and other ESW appllca-
tious may no longer be appropriate due to the unique requirements of Space Station
and due to the availability of new desiEn concepts. A merhodlcol search for the
best design approaches and riEorous enEineerlnE is necessary to avoid time-
consuming and costly correction of design problems. It is concluded that the
cost-effective development of the ESW technology and systems presents an achievable
design challenge.
SYSTEM LEVEL
• ENERGY STORAGE ONLY vs
INTEGRATED WITH ATTITUDE
CONTROL?
• BEST WHEEL ARRAY
CONFIGURATION?
• GIMBALI_ vs NONGIMBALED?
• COUNTER-ROTATING PAIRS _s SKEWED
ARRAYS. err.,.?
• REDUNDANCY & RELIABILITY?
• THERMAL CONTROL?
• ACCOMMODATION OF STATION
GROWTH?
& TECHNOLOGY UPGRADING
ELEMENT LEVEL
• BEARINGS -- BALL vs MAGNETIC?
• MAGNETIC BEARING DESIGN
APPROACH?
• BEST ROTOR SHAPE?, HOOP vs HUB,
etc.?
• MOTOR/GENERATOR TYPE & DESIGN?
• CIRCUITRY?
• COMPOSITE ROTOR DESIGN?
• SAFETY APPROACH?
DESIGN OF ESW SYSTEMS FOR SPACE STATION REPRESENTS A
FORMIDABLE, BUT ACHIEVABLE, DESIGN CHALLENGE
Fisuze 7
6
q
125
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CONCLUSIONS AND RE_ATIONS
_tany supporti_ conclusions are drawn in the text, and the major ones are
s_u_arized in Fig. 8. The F_ concept is found to be a very attractive option
for Space Station (as It was a decade ago). The prompt initiation of a well-
conceived technology development program, includln E laboratory testlnE, is
necessary in order to meet a technology readiness need date that is consistent
with the Space Statlon development goals established by the President. The
destiny of such a technology develcpment progrmnmay well rest on the action of
this workshop.
• THE THREE BASIC TECHNOLOGY BUILDING BLOCKS (MOTOR/GENERATOR/
CIRCUITRY, COMPOSITE ROTORS, & MAGNETIC BEARINGS) ARE ADEQUATELY
DEVELOPED TO PROCEED WITH ESW TECHNOLOGY DEVELOPMENT
• THE MOST IMMEDIATE TECHNOLOGY NEED IS DEFINING HOW TO INTEGRATE
THESE BUILDING BLOCKS INTO A WELL ENGINEERED ESW SYSTEM &
VAODATING ITS PERFORMANCE. LABORATORY PERFORMANCE VERIFICATION
IS MANDATORY
• ADVANCES IN THE THREE BASIC TECHNOLOGY AREAS ARE DESIRABLE & WILL
FURTHER ENHANCE THE APPLICABILITY OF THE CONCEPT
• DEVELOPMENT OF THE ESW TECHNOLOGY & SYSTEMS FOR SPACE STATION
PRESENTS AN ACHIEVABLE, ENGINEERING CHALLENGE
Figure 8
126
IREFERENCES
11 Keckler, C. R.; Rodrlguez, G. E.; and Groom, Nelson 7.
Technology--1983. NASA CT-2290, 1983, p. 5.
i'._tegrate_ Y]-:-_e_,l
Notti, J. E.; Cormack, A., III; Schmill, W. C.; and Klein, l!. ,;.: int=grat_d
Power/Attitude Control System (IPACS) Study, Vol. I--Feasibility Sludies, and
Vol. II--Conceptual Designs. NASA CR-2383, April 1974.
3. Notti, J. E.; and Cormack, A., llI: Design and Testing of an EnerK> Flywheel
for an Integrated Power/Attitude Control System (IPACS). AIAA P_Li;cr 75-]]07,
August 1975.
4. Jarvinen, Philip D.: Advanced Flywheel Storage System. DOE/ET 20279-157,
presented at'Mechanical, Magnetic, and Undergroun_ Energy Storage Contrac_,r_
Review, 1981.
5o
6.
Kulkarni, Satish V.: Flywheel Rotor and Contalament Technology Oevelopmen_
Program of the U.S. Dep_r_ment of Energy. Presented at the Third International
Conference on Composite Materlals, 1980.
Oglevie, R. E.: Space Station Attitude Control--Cila!leuges aud Options.
AAS Paper 83-06"_ presented at the AAS Annual Rocky Mou_tain (;uidance and
Control ConfereLLce, Feb. 5-7, 1983.
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Perspectives on energy storage wheels for space station application

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