NASA Technical Memorandum 100866

Power Components for the l a

20-kHz Power Distribution (NA S A-TH- 1 008 66 ) POW ER CON PONE NT S

Space Station System PO& T H E N 88- 2 1 374

SPACE STATION 20-kHz POMEB D I S T B I B U T I G N SYS7.!l3# (NASA) 10 p csiz 0C)c

Unclas G 3 / 3 1 0 140265

David D. Rem Lewis Research Center Clevelund, Ohio

Prepared for the 23rd Intersociety Energy Conversion Engineering Conference cosponsored by the ASME, AIAA, ANS, SAE, IEEE, ACS, and AIChE Denver, Colorado, July 31-August 5, 1988

https://ntrs.nasa.gov/search.jsp?R=19880011990 2020-05-06T00:17:00+00:00Z

POWER COMPONENTS FOR THE SPACE STATION 20-kHZ POWER DISTRIBUTION SYSTEM

D a v i d D. Renz N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n

L e w i s Research C e n t e r C l e v e l a n d , O h i o 44135

ABSTRACT

S i n c e 1984, NASA L e w i s Research C e n t e r has been d e v e l o p i n g h i g h power , h i g h f r e q u e n c y space power com- p o n e n t s as p a r t of The Space S t a t i o n Advanced Deve lop - ment p r o g r a m . The p u r p o s e o f The Advanced Deve lopmen t

N p r o g r a m was to a c c e l e r a t e e x i s t i n g component p rog rams o t o e n s u r e t h e i r a v a i l a b i l i t y f o r use on t h e Space S t a -

I t i o n . These components i n c l u d e a r o t a r y power t r a n s - f e r d e v i c e , remote power c o n t r o l l e r s , r e m o t e bus i s o l a t o r s , h i g h power s e m i c o n d u c t o r , a h i g h power semi- c o n d u c t o r package , h i g h f r e q u e n c y - h i g h power c a b l e , h i g h f r e q u e n c y - h i g h power c o n n e c t o r s , and h i g h f r e q u e n c y - h i g h pcwer t r a n s f o r m e r s . A l l t h e components have been d e v e l o p e d t o t h e p r o t o t y p e l e v e l and w i l l be i n s t a l l e d i n t h e NASA L e w i s Space S t a t i o n power sys tem t e s t b e d .

OI

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INTRODUCTION

I n t h e l a t e s i x t i e s and e a r l y s e v e n t i e s i t became a p p a r e n t t h a t t h e power r e q u i r e m e n t s o f f u t u r e space- c r a f t w o u l d r i s e from t h e p r e s e n t k i l o w a t t l e v e l t o t h e hundreds o f k i l o w a t t l e v e l b y t h e y e a r 2000. The i n i t i a l space s t a t i o n w h i c h i s p l a n n e d f o r t h e m i d d l e n i n e t i e s has a p r o j e c t e d power l e v e l o f 7 5 kW w i t h a g r o w t h p o t e n t i a l o f 300 kW.

A low v o l t a g e dc d i s t r i b u t i o n s y s t e m w i l l not be s u i t a b l e due t o t h e l a r g e c o n d u c t o r w e i g h t r e q u i r e d t o c a r r y t h e c u r r e n t s . An o b v i o u s so lu t ion to r e d u c i n g c o n d u c t o r w e i g h t i s t o r a i s e t h e o p e r a t i n g v o l t a g e . A n o t h e r way t o r e d u c e w e i g h t i s t o use a h i g h f r e - quency a t sys tem w h i c h d e c r e a s e s b o t h w e i g h t and s i z e o f m a g n e t i c d e v i c e s such as t r a n s f o r m e r s .

A t t h e b e g i n i i n g o f t h e Space S t a t i o n P rog ram, NASA p e r f o r m e d an e x t e n s i v e power s y s t e m t r a d e s t u d y c o m p a r i n g 150 V dc , 440 V-400 H z , and 440 V-20 kHz . The c o n c l u s i o n o f t h i s t r a d e s t u d y was t h a t t h e 440 V-20 kHz power s y s t e m was t h e mos t e f f i c i e n t , l i g h t e s t , and l o w e s t i n - c o s t . The s t u d y a l s o showed t h a t t h e 440 V-20 kHz power s y s t e m h a d no t e c h n i c a l show s t o p p e r s b u t t h a t t h e 20 kHz component t e c h n o l o g y was n o t as f u l l y d e v e l o p e d as t h a t o f t h e o t h e r power s y s terns.

NASA L e w i s has been d e v e l o p i n g power components for some t i m e t h a t t a k e a d v a n t a g e o f b o t h h i g h v o l t - age and h i g h f r e q u e n c y ( 1 ) . The Space S t a t i o n Advanced Deve lopmen t p r o g r a m augmented t h e s e e x i s t i n g p rog rams and s t a r t e d new ones on a n a c c e l e r a t e d sched- u l e t o e n s u r e t h a t t h e components w o u l d be a v a i l a b l e f o r use i n t h e Space S t a t i o n Power Sys tem. The o b j e c - t i v e o f t h i s p a p e r i s t o summar ize t h e Space S t a t i o n Advanced Deve lopmen t P rog ram for space power compo- n e n t s and p r o v i d e a comprehens ive r e p o r t .

ROTARY POWER TRANSFER DEVICE

I n t h e e a r l y e i g h t i e s , S p e r r y F l i g h t Sys tems deve- l o p e d f o r NASA Lew is a m u l t i h u n d r e d k i l o w a t t Rol l R i n g assemb ly ( 2 ) . The Rol l R i n g i s a d e v i c e t h a t t r a n s - f e r s e l e c t r i c a l power a c r o s s a r o t a t i n g j o i n t through r o t a t i n g f l e x u r e s compressed be tween c o n c e n t r i c con- d u c t o r s ( F i g . 1 ) . The a d v a n t a g e s o f t h e Ro l l R i n g o v e r t h e s l i p r i n g a r e t h e e l i m i n a t i o n o f s l i d i n g f r i c t i o n and t h e low t o r q u e needed t o r o t a t e t h e d e v i c e . The Ro l l R i n g c a n t r a n s f e r b o t h a c and d c power and has a measured e f f i c i e n c y o f 0 .9998 ( 3 ) . There a r e e i g h t c i r c u i t s i n t h e assemb ly ( F i g . 2 ) each c a p a b l e of c o n d u c t i n g 200 A a t 500 V d c . T h i s Ro l l R i n g assemb ly won a 1985 IR-100 award f o r one of t h e b e s t new p r o d u c t s o f t h a t y e a r .

A second Rol l R i n g assemb ly was b u i l t for NASA L e w i s w i t h f o u r c i r c u i t s ( t h e f i r s t a s s e m b l y h a d e i g h t c i r c u i t s ) ( F i g . 3 ) . The Space S t a t i o n Advanced D e v e l - opment p r o g r a m r e d e s i g n e d t h e 4 - c i r c u i t Roll R i n g assemb ly a f t e r e v a l u a t i o n t e s t i n g (3) t o d e c r e a s e t h e o u t g a s s i n g t i m e o f t h e assemb ly and t o e l i m i n a t e pos - s i b l e c o r o n a p r o b l e m s . P r e s e n t l y , t h e Ro l l R i n g i s b a s e l i n e d as t h e Space S t a t i o n a l p h a - j o i n t power t r a n s f e r d e v i c e . The four c i r c u i t Roll R i n g assemb ly i s s t i l l u n d e r g o i n g 440 V-20 kHz vacuum t e s t i n g a t NASA L e w i s ( F i g . 4 ) . The Rol l R i n g assemb ly i s c o r o n a checked e v e r y f e w months d u r i n g t h e vacuum l i f e t e s t . B o t h a s s e m b l i e s have a c c u m u l a t e d i n excess o f 60 Space S t a t i o n y e a r s of r o l l i n g t i m e ( 8 - c i r c u i t Ro l l R i n g assemb ly - 6 4 y e a r s , 4 - c i r c u i t Roll R i n g assemb ly - 114 y e a r ) a t 100 A or g r e a t e r ( 3 ) . Thus f a r t h e Ro l l R i n g a s s e m b l i e s have met or exceeded a l l s p e c i f i - c a t i o n s o f t h e o r i g i n a l c o n t r a c t .

ONGINAD PAGE IS OF POOR QUALITY

HIGH POWER SEMICONDUCTOR

General Electric Company is presently under con- tract with NASA Lewis to produce a high voltage MCT (Mos Controlled Thyristor) (4). The MCT under devel- opment for NASA Lewis is a 1200 V, 40 A device with a switching time of one microsecond and forward drop of 1 v. turn-off. thyristor, and MCT representative schematics (5). The MCT is planned to be used on the Space Station in remote power controllers, main inverters, frequency changers, charge/di;cnarge converters and motor con- trollers. The MCT with a 1000 V to 40 A rating will be commercially avaiiable in the fall of 1988.

The MCT also requires low gate drive power for Figure 5 shows the transistor equivalent,

allow for system failure analysis. Figure 10 shows a 100-A RBI without a control card.

HIGH POWER SEMICONDUCTCR PACKAGE

Power Technology Components developed a high power semiconductor package for NASA Lewis (6). This pack- age has low inductance due to the lead configuration and electrically isoidtes the power chip from the case. The package I ; hermetically sealed and has an internal coating of pdrylene (Union Carbide Corp. Trademark) which provides voltage breakdown protec- tion in case the hermetic seal fails (Figs. 6 and 7 ) .

The MCT chip will be mounted in this package and then tested in the various Space Station test bed cir- cuits. Power Technology Components has a commercial version without the parylene coating marketed as their "power mode" series.

REMOTE POWER CONTROLLERS AND REMOTE BUS ISOLATERS

Leach Corporation i s developing for NASA Lewis a family o f 208 V rms - 20 kHz remote power controllers (RPC's) (5, 10, 25 A) and a family of 440 V rms - 20 kHz remote bus isolators (RBI's) (25, 50, 100 A) ( 7 ) . The RPC's are current limiting switches that isolate the power distribution system from load faults ( 8 ) . If a load faults, the RPC switches in a current limiting reactance within 2 ps, limits the fault to 300 percent of the RPC rating and removes the load at the end of this first half cycle of operation (25 psec) The RPC's will accept on and off commands and current trip point commands. The RPC will supply to the data system the status (on or off), load current, load volt- age, sign o f the volt-ampere product and the last cur- rent reading before tripping. This last current read- ing will allow time for system failure analysis while protecting the system from overload. The Leach RPC uses parallel FET's for the switching function and has a metal contact relay in series for dead heading the switch. Figure 8 shows an 8-A FET power hybrid module and Fig. 9 shows a 25-A RPC which mounts four hybrid modules on the control card. In the next generation design the Mos Controlled Thyristor (MCT) will replace the FET's.

The remote bus isolators (RBI's) are metal contac- tors that are used for power bus reconfiguration ( 7 ) . Under normal operating conditions, they will not be switched under load. Testing at NASA Lewis has shown that they may be switched when current is flowing but this is not desirable. The RBI's will only accept on and off commands. The RBI's will supply to the data system the status (on/off), bus current, bus voltage, sign of the volt-ampere product and the last current reading when power is removed from the bus. This last current reading plus the volt-ampere product will

POWER CABLE AND CONNECTORS

In 1980, Induction General, Inc. developed for NASA a high power, low inductance, 20 kHz cable (9). The main reason for the low inductance was to reduce the external magnetic field of the cable, it also improved the cable voltage drop and minimized the cross ralk between the loads. The cable was constructed as a double sided strip line using straps made o f Lit2 wire (Fig. 1 1 ) . The Litz wire cable was designed to deliver 25 kW with a 2 percent real loss over 50 m . The Induction General cable parameters were: resist- ance: 0 . 8 3 m - Q / m , inductance: 0.035 micro-H/m, capacitance: 0.00137 micro-F/m, and weight: 1 kg/m.

onstrate that a low inductance cable was possible. The Litz wire cable showed some problems, such as: very long out gassing times due to gasses trapped in the Litz wire, holding cable configuration constant during the manufacturing process (caused field induct- ance to increase), not very flexible and fairly heavy. A second generation cable is being made for NASA Lewis by W.L. Gore and Associates, Inc. (10). This cable design uses solid flat foil conductors instead of the Litz wire braid. The foil conductors also were covered with a solid dielectric coating and outgassing will be achieved by using a gas permable dielectric for a filler and outer jacket material. This cable will have approximately the same electrical parameters as the Li tz cable, better uniformity duriog the manufacturing process, but will weigh less and have greater flexi- bility (Fig. 1 1 ) .

440 V - 20 kHz - 30 kVA connector for terminating the 20 kHz flat foil cable being developed by GORE (11). The connector being designed for NASA Lewis has a voltage drop of 0.375 V at rated current (68 A) and will weigh approximately 1 lb. It is also being de- signed for handling with space suit type gloves (Fig. 12).

The Induction General cable was developed to dem-

G&H Technology, Inc. is developing for NASA a

TRANSFORMERS

TRW is developing for NASA Lewis a 440/220, 2 0 kHz, 25 kVA transformer (12). The wiring schematic of this transformer is shown in Fig. 13. The measured leakage inductance is 1.6 micro-H, which exceeds the specifi- cation limit o f 3 . 0 micro-H. The measured efficiency of 99.36 percent exceeds the design goal of 98 percent and the unit weighs approximately 10 lbs. unpotted (Fig. 14). Figure 14 shows the unpotted transformer along with one seven turn secondary. This transformer will be installed in the NASA Lewis Space Station power system test bed for evaluation and system tests.

REFERENCES

I . Renz. D . D . , 1984, "High Voltage - High Power Components for Large Space Power Distribution Sys terns ," NASA TM-83648.

2. Jacobson, P.E., 1985, "Multi-Hundred Kilowatt Rol 1 Ring Assembly," NASA CR-174832.

3. Renz, D.D., 1988, "Multi-Hundred Kilowatt Roll Ring Evaluation Results," NASA TM-100865.

ORIGINAL PAGE IS OF POOR QILTALITY

2

4 . Renz, D . D . , Project Manager, 1988, "Development o f Fas t S w i t c h i n g - H igh Power Semiconductors , " General E l e c t r i c Co., Schenectady, NY, NASA C o n t r a c t NAS3-24898.

5. TemDle. V . A . K . . 1987. "MOS C o n t r o l l e d T h y r i s t o r s i n Energy Convers ion Systems," Enerqy - New F r o n t i e r s (22nd IECEC). A I A A , New York.

6. B a l o d i s , V . , Berman, A . , Devance, D . . Ludlow, G . . and Wagner, L . , 1987, "Space S t a t i o n Power S e m i - conductor Package," NASA CR-180829.

7 . Renz, D.D., Project Manager, "Remote Power Con- t r o l l e r and Bus I s o l a t e r , " Leach C o r p o r a t i o n , NASA C o n t r a c t NAS3-24660.

8 . T o f i q h . F., 1987. "208VAC. 20 kHz H y b r l d Remote Powet C o n t r o l l e r , " Energy - New F r o n t i e r s (22nd I E C E C ) , A I A A . New York .

9 . 1986, "H igh Frequency Power D i s t r i b u t i o n System." NASA CR-175071.

10. Renz, D.D., P r o j e c t Manager, 1988, "H igh Power Connector Development, Task 5,'' TRW Space Technology Labs, NASA C o n t r a c t NAS3-24667.

1 1 . Renz, D . D . , P r o j e c t Manager, 1988, "H igh Power Connector Development, Task 7," TRW Space Technology Labs, NASA C o n t r a c t NAS3-24667.

o f 20 kHz - 2 5 kVA Trans former for Space S t a t i o n , Task 4 , " TRW Space Technology Labs, NASA C o n t r a c t

12. Gourash, F., P r o j e c t Manager, 1988, "Development

NAS3-24667.

FIGURE 1. - SINGLE ROLL RING CIRCUIT.

3

r OUTPUT TERM1 NAL I

FIGURE 2. - CROSS SECTION OF THE 8 - C I R C U I T ROLL R I N G EVALUATION U N I T .

INNER ,? OUTER

a, BARRIERS CONDUCTOR R I N G 7,

I CONDUCTOR ' R I N G I

INPUT , 1

TERN I NAL CD-84-14533

I I- OUTPUT

TERN I NAL

F IGURE 3. - FOUR C I R C U I T ROLL R I N G ASSEMBLY,

4 'ORIGINAL PAGE IS OB POOR QU-ALITY

A

FIGURE 4. - FOUR C I R C U I T ROLL RING ASSEMBLY IN VACUUM TESl

bC TRANSISTOR EQUIVALENT

FIGURE 5 .

d C

THYR I STOR

REPRESENTATIVE SEMICONDUCTOR

f A C

NOS CONTROLLER THYR I STOR

SCHEMATICS .

5

FIGURE 6. - POWER SEMICONDUCTOR PACKAGE

FIGURE 8. - FET POWER HYBRID ( 8 AMP) M0I)ULE.

J FIGURE 7 . - HERMETIC. HIGH POWER SEMICONDUCTOR PACKAGE.

C-88-03392

FIGURE 9. - 25 AMP REMOTE POWER CONTROLLER.

4 4 0 V - l O O A - I “ - --m

FIGURE 10. - 100 AMP REMOTE BUS ISOLATOR (NO CONTROL CARD).

F I G U R E 11. - TWO 20 KHZ CABLE C O N F I G U R A T I O N S .

7

F I G U R E 12. - 20 KHZ BUS CONNECTOR.

CORE

20 KHz

FIGURE 13. - 440/220, 25 KVA TRANSFORMER SCHEMATIC.

FIGURE 14. - 25 KFA-20 KILOHURTZ TRANSFORMER.

8 ORIGINAL PAGE IS OE POOR QUALITY

Nalmnal NASA Aeronautics and Report Documentation Page Space Admlntslral~on

1. Report No.

NASA TM-100866 2. Government Accession No.

7. Author@)

D a v i d D . Renz

7. Key Words (Suggested by Author@))

Space power components; Vacuum power components; Power d i s t r i b u t i o n components; H i g h f requency components

9. Performing Organization Name and Address

N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n Lewis Research Cen te r C l e v e l a n d , O h i o 44135-3191

18. Distribution Statement

U n c l a s s i f i e d - U n l i m i t e d S u b j e c t Ca tegory 31

~~~ ~~

12. Sponsoring Agency Name and Address

9. Security Classif. (of this report)

Unc 1 ass i f i e d

N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n Washington, D . C . 20546-0001

21. No of pages 22. Price' 20. Security Classif. (of this page)

U n c l a s s i f i e d 10 A02

15. Supplementary Notes

3. Recipient's Catalog No.

5. Report Date

6. Performing Organization Code

8. Performing Organization Report No.

E-4092

10. Work Unit No.

481 -54-32

11. Contract or Grant No.

13. Type of Report and Period Covered

T e c h n i c a l Memorandum

14. Sponsoring Agency Code

Prepared f o r t h e 2 3 r d I n t e r s o c i e t y Energy Convers ion E n g i n e e r i n g Conference cosponsored by t h e ASME, A I A A , ANS, SAE, I E E E , ACS, and AIChE, Denver , Co lo rado , J u l y 31 - August 5 , 1988.

16. Abstract

S i n c e 1984, NASA Lewis Research Cen te r has been d e v e l o p i n g h i g h power, h i g h f r e - quency space power components as p a r t o f The Space S t a t i o n Advanced Development program. e x i s t i n g component programs t o ensure t h e i r a v a i l a b i l i t y for use on t h e Space S t a t i o n . These components i n c l u d e a r o t a r y power t r a n s f e r d e v i c e , remote power c o n t r o l l e r s , remote bus i s o l a t o r s , h i g h power semiconduc to r , a h i g h power semi- c o n d u c t o r package, h i g h f requency -h igh power c a b l e , h i g h f r e q u e n c y - h i g h power c o n n e c t o r s , and h i g h f r e q u e n c y - h i g h power t r a n s f o r m e r s . A l l t h e components have been deve loped t o t h e p r o t o t y p e l e v e l and w i l l be i n s t a l l e d i n t h e Lewis Research Cen te r Space S t a t i o n power system t e s t bed.

The purpose o f The Advanced Development p rogram was t o a c c e l e r a t e