Design and evaluation of motor inverter with current sensing and limiting circui

Irvine, D. B.

English

Performance tests and torque-speed graphs for motor ring-counter inverter syste

NASA Technical Reports Server

* :  
* . *  , m 
REPORT NO.: 2L94 - .. 
v;. 
, ;* '- ,fp' 4 '''CONTRACT NO. : NaS8-20832 
DATE: APRIL  3,  1968 
A/bB-236~)3 
-eR- L7175EY 
THIRD QUARTERLY PROGRESS REPORT 
(PERIOD ENDING MARCH 2 5 ,  1 9 6 8 )  
FOR 
APPLIED RESEARCH AND FEASIBILITY STUD- 
I E S ,  EXPERIMENTAL INVESTIGATIONS AND 
CONCEPTUAL OR PRELIMINARY DESIGN ENG- 
INEERING APPLICABLE TO INVERTERS FOR 
MOTORS PROGRAM. 
PREPARED BY 
GULTON INDUSTRIES, INC . 
E n g i n e e r e d  Magnetics D i v i s i o n  
NATIONAL 
13041 C e r i s e  A v e n u e  
Hawthorne, C a l i f o r n i a  
FOR 
AERONAUTICS AND SPACE ADMINISTRATION 
MARSXALL SPACE FLIGHT CENTER 
HUNTSVILLE, ALABAMA 
Gulton Industrbs, Inc. 
ENGINEERED MAGNETICS DIVISION 13041 CERISE AVE., HAWTHORNE, CALIF. 
https://ntrs.nasa.gov/search.jsp?R=19680014134 2020-03-12T10:37:53+00:00Z
REPORT NO. : 2194 
CONTRACT NO.: NAS8-20832 
DATE: A P R I L  3, 1968 
THIRD QUARTERLY PROGRESS REPORT 
(PERIOD ENDING MARCH 25, 1 9 6 8 )  
FOR 
APPLIED RESEARCH AND F E A S I B I L I T Y  STUD- 
I E S ,  EXPERIMENTAL INVESTIGATIONS AND 
CONCEPTUAL OR PRELIMINARY DESIGN ENG- 
INEERING APPLICABLE TO INVERTERS FOR 
MOTORS PROGRAM. 
SUBMITTED BY: 
D. B. I rv ine  
REVIEWED BY: 
APPROVED BY: A,g fwl, (“xr, l* - 
B. 3 .  McComb 
V i c e  President  
E n g i n e e r e d  Magnetics 
D i v i s i o n  
PREPARED BY 
GULTON INDUSTRIES, INC . 
E n g i n e e r e d  netics D i v i s i o n  
13041 ise A v e n u e  
H a w t h o r n e ,  C a l i f o r n i a  
FOR 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
MARSHALL SPACE FLIGHT CENTER 
HUNTSVILLE, ALABAMA 
TABLE OF CONTENTS 
ABSTRACT, 
PREFACE, 
I .  INTRODUCTION. 
11, WORK ACCOMPLISHED: THIS  REPORT PERIOD. 
111. WORK PLANNED: NEXT MONTHLY REPORTING PERIOD. 
APPENDIX I .  QUARTERLY REPORT DISTRIBUTION L I S T ,  
PAGE NO. 
iii 
1 
2 
3 
20 
ii 
ABSTRACT 
This is the Third Quarterly Progress Report for Engineered 
Magnetics' Applied Research and Feasibility Studies, Ex- 
perimental Investigations, And Conceptual Or Preliminary 
Design Engineering Applicable To Inverters For Motors. This 
report describes the accomplishments achieved during the 
period from December 26, 1967 to March 25, 1968. This report 
presents information pertaining to Inverter/motor system tests. 
iii 
PREFACE 
The National  Aeronautics and Space Administration Cont rac t  
Number NAS8-20832, Applied Research and F e a s i b i l i t y  S tudies ,  
Experimental Inves t iga t ions  and Conceptual or Prel iminary 
Design Engineering Applicable To I n v e r t e r s  For Motors 
Program, w a s  awarded t o  t h e  Engineered Magnetics Divis ion 
of Gulton I n d u s t r i e s ,  Inc. ,  on June 22 ,  1967, 
T h i s  is t h e  Third Q u a r t e r l y  Progress  Report pe r t a in ing  t o  
t h e  Engineered Magnetics Applied Research and F e a s i b i l i t y  
s t u d i e s  of I n v e r t e r s  f o r  Motors Program, present ing  t h e  
progress  of t h e  program from D e c e m b e r  26, 1967 t o  March 25, 
1968. This r e p o r t  con ta ins  a review of t h e  t e c h n i c a l  in- 
formation which has  guided t h e  dec i s ions  and accomplish- 
ments fo r  t h i s  per iod,  
-1- 
I. INTRODUCTION 
Thie is the Third Quarterly Progress Report for 
Engineered MagnetiCo' Applied Research And Fea- 
sibility Studies, Experimental Investigation., 
And Conceptual Or Preliminary Design Engineering 
Applicable To Invertera For Motors. 
During this report period, two new motors were received 
and a 6 phase ring-counter inverter waa fabricated. 
Several tests w e r e  c o n d u c t e d  u s i n g  v a r i o u s  motor 
input configurationo to obtain comparison curves of 
motor torque vs speed. The results of these teats 
are preoented in this report. 
-2- 
11. WORK ACCOMPLISHED: THIS REPORT PERIOD. 
1. TEST MOTORS. 
The t w o  motors mentioned i n  previous r e p o r t s  as being 
ordered for t h i s  p r o j e c t ,  a r r i v e d  a t  Engineered Magnetics. 
The manufacturers '  ope ra t ing  curves f o r  t h e  motors are 
presented on Figures  1 and 2 .  
except for d i f f e r e n c e s  i n  s t a t o r  material. The s ta tor  
of Motor No .  1 ( 8 5 8 0 - C 9 3 4 5 )  con ta ins  type M 1 9  s i l i c o n  
steel, and t h e  stator of Motor No.  2 ( 8 5 8 0 - C 9 3 4 6 )  con ta ins  
type Allegheny Ludlum 4 7 5 0  s t a i n l e s s  steel .  
The t w o  motors are i d e n t i c a l  
The motor opera t ion  curves,  Figures  1 and 2 i n d i c a t e  a 
f u l l  load e f f i c i e n c y  of 87% f o r  Motor N o .  1 and 80% f o r  
Motor No .  2 ,  The reason f o r  the  extremely high e f f i c i e n c y  
of t h e  t w o  motors is apparent ly  a r e s u l t  of t h e  u s e  of 
overs ize  cons t ruc t ion  i n  r e l a t i o n  t o  t h e  requi red  power 
and frequency r a t i n g ,  which permits t h e  u s e  of l a r g e  
w i r e  size, and apparent ly  low magnetic s a t u r a t i o n .  When 
t h e  curves of Figures  1 and 2 are compared wi th  t h e  
curves f o r  motor 8081-C8785 (See EM Report N o .  2068) t h e  
inc rease  i n  e f f i c i e n c i e s  becomes very d i s t i n c t  (68% vs  
87% a t  f u l l  l oad ) .  The new motors have e x t e r n a l  diameters 
(excluding r a d i a t i n g  f i n s )  of 3-1/2 inches opposed t o  t h e  
2-1/2 inches e x t e r n a l  diameter (excluding r a d i a t i n g  f i n s )  
of t h e  o r i g i n a l  motor. 
2 ,  INVERTER BREADBOARD DESIGN.  
A s ix  phase ring-counter w a s  f a b r i c a t e d  t o  opera te  t h e  
motor. The engineers  sketch,  Figure 3 ,  presents  t h e  
latest  I n v e r t e r  c i r c u i t  design.  The  l o g i c  funct ions des- 
cribed i n  t h e  second Q u a r t e r l y  Progress  Report (EM 
Report N o .  2161) w e r e  no t  used as t h e  c i r c u i t  descr ibed  
i n  t h a t  r e p o r t  d i d  not  produce t h e  d e s i r e d  waveforms. 
c i r c u i t  shown on Figure 3 funct ions wi th  cons tan t  s l i p  frequency 
opera t ion .  
The 
-3- 



3 ,  INVERTER/MOTOR SYSTEM TESTS. 
Motor No, 1 w a s  subjected t o  Inverter/Motor system tests, 
The tests w e r e  conducted wi th  f i x e d  motor i n p u t  frequency 
and va r i ed  inpu t  vo l t age  conf igu ra t ions  t o  e s t a b l i s h  
system e f f i c i e n c y .  The system tests included 6 phase 
quasi-square wave motor inpu t  and 6 phase s q u a r e  wave 
motor i npu t  (each motor inpu t  conf igu ra t ion  w a s  app l i ed  
wi th  and wi thout  i n t e rphase  t ransformers)  as shown on 
Figure 4. Figures  4 and 5 i l l u s t r a t e  t h e  test  se tup ,  
Figure 6 d e p i c t s  system e f f i c i e n c y  during t h e  above 
tests. I n v e r t e r  No. 2 ,  t h e  I n v e r t e r  developed by EM 
f o r  t h e  previous NASA I n v e r t e r s  f o r  Motors Study 
Program (NASA Contract  No.  NAS8-18013), w a s  used  i n  
t h e  s e t u p  (see Figure 5 ) .  With no power app l i ed  t o  t h e  
test  motor, I n v e r t e r  No. 2 and t h e  load motor w e r e  
ad jus t ed  f o r  a nominal s h a f t  speed of 7600 RPM. Therefore,  
when input  power w a s  appl ied  t o  t h e  t es t  motor t h e  system 
increased i n  speed t o  a po in t  where t h e  load motor absorbed 
t h e  power de l ive red  by t h e  t e s t  motor. E f f i c i ency  w a s  
c a l c u l a t e d  by d iv id ing  t h e  load motor s h a f t  output  power 
( W a t t s  Power = 0.00074 X R P M  X 02 - I N  TORQUE) by system 
inpu t  power (P = I E ) .  T e s t  measurements obtained a t  
s e v e r a l  i npu t  power l e v e l s  are presented on Figure 6 ,  
These measurements i n d i c a t e  t h e  following: 
A, Maximum e f f i c i e n c y  is obtained w i t h  a s l i p  of 3 t o  5%. 
B. Quasi-square wave motor input  r e s u l t s  i n  more e f f i c i e n t  
opera t ion  than does a square wave motor input .  
C. The in te rphase  t ransformer improves t h e  e f f i c i e n c y  of 
quasi-square wave motor i n p u t  opera t ion  approximately 
2%, and improves s q u a r e  wave motor i n p u t  ope ra t ion  
8 t o  10%. 
A t  t h e  conclusion of t h e  above tests, t h e  I n v e r t e r  and motor 
wi r ing  conf igu ra t ion  were r ev i sed  t o  permit opera t ing  t h e  
-7-,  
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motor as a Wye connected motor w i t h  a 3 phase q u a s i -  
square wave input .  The b i f i l a r  motor windings,  connected 
i n  p a r a l l e l ,  and t h e  I n v e r t e r  ou tput  s e c t i o n  conf igu ra t ion  
are shown on Figure 7. 
System tests w e r e  conducted using s e v e r a l  d i f f e r e n t  
nominal motor i npu t  f requencies  and vol tages  as shown 
on Figures  8 through 11. The frequencies  recorded on 
t h e  graphs r ep resen t  nominal osc i l la tor  frequencies  
(6 X fout).  As a r e s u l t  of t h e s e  tests t h e  following 
information w a s  obtained.  
A .  Figure 9 i n d i c a t e s  t h e  s l i p  frequency i n  Hz must  
be cons tan t  t o  ob ta in  m a x i m u m  e f f i c i e n c y  wi th  cons tan t  
l e v e l  i npu t  vo l tage .  
B, The 400 Hz i npu t  (2400 Hz curves) ob ta ins  m a x i m u m  
e f f i c i e n c y  a t  4% s l i p  (16 Hz); t h e  300 Hz input  
(1800 Hz curves) ob ta ins  m a x i m u m  e f f i c i e n c y  a t  5% 
s l i p  (15 Hz); t h e  200 Hz i npu t  (1200 Hz curves) 
ob ta ins  m a x i m u m  e f f i c i e n c y  a t  7.5% s l i p  (15 H z ) .  
The inpu t  is 24 v o l t s .  (See Figure 9.) Figures  8, 
10, and 11 show a g r e a t e r  percentage of s l i p .  T e s t s  
conducted a t  lower motor inpu t  f requencies  wi th  
h igher  input  vo l tage  d i d  not  r e s u l t  i n  any meaningful 
information due t o  excessive s a t u r a t i o n  affects.  
By comparing t h e  d a t a  f o r  each cons tan t  vo l tage  and 
cons t an t  frequency and then comparing t h e  d a t a  of t h e  
curves f o r  2400 Hz a t  24 v o l t s ,  1800 Hz a t  18 v o l t s ,  and 
1200 Hz a t  12 v o l t s ,  optimum s l i p  is e s t ab l i shed  t o  be 
4% (16 ( H z ) ,  5% (15 H z ) ,  and 6% ( 1 2  H z )  r e spec t ive ly .  
A l s o  noted as a r e s u l t  of t h e  system tests w a s  t h a t  t h e  
e f f i c i e n c y  is  s l i g h t l y  higher  w i th  the conventional 3 phase 
quasi-square wave motor input  shown on Figures  8-11 than 
wi th  either 6 phase motor input  shown on Figure 6 .  
-11- 
I, 
f 
m 
-12- 
-13- 
- 7  4- (%) A3N3131dJ3 
tn 
‘1 
\ 
-. 
1 
-16- (%) A 3 N B I  31 683 
4 .  INVERTER BRmDBOARD TEST. 
The six phase r i n g  - counter  (quasi-square wave) i n v e r t e r  
c u r r e n t  and vo l t age  waveform photographs shown o n  F igu res  1 2  
and 13 a r e  for Motor No, 1 opora t ion .  The locked rotor current 
res.mbloa a sin. wave, b u t  t h o  normal load c u r r e n t  presents 
sharp  d iocon t inu i t ioa .  During t h o  t o a t  it w a s  no t i ced  t h a t  
d i o i k  c u r r o n t  flowod back i n t o  t h e  powor source and appeared 
whon t h e  oppooed b i f i l a r  winding curront  waa switched off. 
The six phase ring-countor logic (rof Figuro 3)  oporates as 
f o l l o w s .  (&tor Tl10 curvos roproeont  optimum operation.) 
1
Count FF1 FF2 FF3 
1 1 0  0 
2 1 1  
3 1 1  
4 0 1  
5 0 0  
6 0 0  
1 1 0  
-
C o u n t  1 2 3 4 5 6  1 2 3  
- 
With t h e  b i f i l a r  winding reprosentod  an $A, t h e  phase c u r r e n t s  
with a r e s i s t i v o  load w o u l d  be a s  fol lows:  
Count 1 2 3 4 5 h l  
$A-a 0 --.I 
- I-.- 
+ 
1 I 
-17- 
TYPICAL WAVEFORMS 
MOTOR CURRENT. 
PHASE A WINDING CURRENT. 
VERT: 10A/DIV, 
GATE OUTPUT 
VERT , : 5V/DIV. 
OUTPUT TRANSISTOR. 
COLLECTOR VOLTAGE 
VERT. : 2OV/DIV. 
GATE OUTPUT, 
VERT.: 5V/DIV 
PHASE A CURRENT DIODE. 
DIODE CURRENT 
VERT. : 10A/DIV. 
GATE OUTPUT 
VERT.: 5V/DIV 
HORIZ : 100pSEC/DIV (ALL WAVEFORMS) 
INPUT FREQ.: 400Hz (ALL WAVEFORMS) 
FIGURE 12 .  MOTOR NO.l/INVERTER TEST RESULTS. 
-18- 
LOCKED ROTOR 
PHASE A - PHASE a 
CURRENT 
VERT, : 10A/DIV. 
PHASE A - PHASE a 
VOLTAGE 
VERT. : lOV/DIV. 
NORMAL LOAD 
PHASE A - PHASE a 
CURRENT 
VERT , : 10A/DIV. 
PHASE A - PHASE a 
VOLTAGE 
VERT. : 2OV/DIV. 
HORIZ: 100pSEC/DIV (ALL WAVE FORMS) 
INPUT FREQ.: 400 Hz (ALL WAVE FORMS) 
FIGURE 13 .  MOTOR NO.l/INVERTER TEST RESULTS (CONT'D) . 
-19- 
111. WORK PLANNED: NEXT REPORTING PERIOD. 
Inverter/motor tests w i l l  be conducted to obtain curves 
for further evaluation of system operation. 
-20- 
APPENDIX I 
QUARTERLY REPORT D I S T R I B U T I O N  LIST 
ADDRESSEE NUMBER OF COPIES 
National Aeronautics and Space Administration 
Electronics Research Center 
Cambridge, Ma8srChUsettS 02139 
ATTN: Dr. Francis C. Schwarz 
National Aeronautics and Space Administration 
Atnos Resoarch Center 
Moffatt Field, California 94035 
ATTN: Jams Swain 
Jet Propulsion Laboratory 
4800 Oak Grove Drive 
Pasadena, California 91103 
A m :  Paul Goldsmith 
Alden Schloss 
Kirk M. Dawson 
Naval Research Labor8tory 
Departmont of tha Navy 
Washington, D. C. 20390 
AT!PNl B. J. Wilson (Cod. 5230) 
Naval Air Sya tams Command 
Department of the Navy 
Washington, D. C. 20360 
ATTN: Milton Knight (Code AIR-340C) 
U. S. Air Force Aeropropulsion Laboratory 
Wright Patterson AFB 
Dayton, Ohio 45433 
ATTN: APIE-3 
U. S. Army Engineer R and D Laboratory 
Energy Conversion Branch 
Ft. Belvoir, Virginia 22060 
AWN: Ralph E. Hopkins 
U. S. Army R and D Laboratory 
Energy Conversion Branch 
Ft. Monmouth, New Jersey 07703 
A m :  H. J. Byrnes 
Pcmor Information Center 
Moor. School Building 
200 South 33rd Street 
Philadalphia, Pennsylvania 19104 
1 
1 
1 
1 
1 
1 
1 
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This report w a s  distributed to the follawing addresses: 
ADDRESSEE NUMBER OF COPIES 
National Aeronautics and space Administration 
Scientific and Technical Information Facility 
College Park, Maryland 20740 
ATTN: NASA Representative 3 
(+ 1 Reproducible) 
Nation81 Aeronautics and Space Administration 
Washington, D. C. 20546 
A m :  Preston T. Maxwell (RNW) 
James J. Lynch (RNP) 
A. M. Greg Andrus (ST) 
National Aeronautics and Space Administration 
Manned Spacecraft Center 
Houston, Texas 77058 
A"N: W. E. Rice 
F. E. Eastman 
National Aeronautics and Space Administration 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
ATTN: William R. Cherry 
Fred C. Yagerhofer 
Charles M. Mackenzie 
E. R. Pasciutti 
National Asronautica and Space Administration 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
A m :  Richard Boohme (R-ASTR-E) 
Roy Lanier, Jr. (R-ASTR-EX) 
National Aeronautics and Space Administration 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
ATTN: Hcrward Shumaker 
Charles Corcoran 
National Aeronautics and Space Administration 
Langley Research Center 
Instrumant Research Division 
Hampton, Virginia 23365 
ATTNr John L. Patterson, MS-234 
1 
1 
1 
1 
1 
1 
1 
1 
1 
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1 
1 
1 
ADDRESSEE 
Duko University 
Collego of Engineering 
Deprrtmont of El8CtriCal Engineering 
Durham, North Carolina 27706  
A!PXW: Professor T. G .  Wilson 
U. S .  Army Electronics command 
Fort Monmouth, Now Jorsoy 07703 
A m :  M r .  W .  L .  Dudley 
AblSEL-KL-PE 
National Aoronauties and Space Administration 
Marshall Space F l i g h t  Center 
Huntsville,  Alabama 35812 
ATTN: PR-RC 
MS-IL 
MS-T 
MS-I 
R-ASTR-Z 
NUMBER OF COPIES 
1 
1 
(+ 1 Reproducible) 


Applied research and feasibility studies, experimental investigations and conceptual or preliminary design engineering applicable to inverters for motors program  Quarterly progress report, period ending Mar. 25, 1968

Applied research and feasibility studies, experimental investigations and conceptual or preliminary design engineering applicable to inverters for motors program  Quarterly progress report, period ending Jun. 25, 1968

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REPORT NO.: 2090 
CONTRACT NO.: NAS8-20832 
DATE: OCTOBER 5, 1967 
F I R S T  QUARTERLY PROGRESS REPORT 
(PEEUOD ENDING SEPT-ER 25, 1967) 
FOR 
APPLIED RESEARCH AND F E A S I B I L I T Y  STUD- 
I E S ,  EXPERIMENTAL INVESTIGATIONS AND 
CONCEPTUAL OR PRELIMINARY DESIGN ENG- 
INEERING APPLICABLE TO INVERTERS FOR 
MOTORS PROGRAM. 
D. B. I rvine 
P r o  j ect ,mineer  
REVIEWED BY: i 
J.;Ff. B a t e s  
P r 4 d u c  t Manager 
h 
APPROVED BY: 
McCo 
V i c e  President 
Engineered Magnetics 
D i v i s i o n  
PREPARED BY 
GULTON INDUSTRIES, INC. 
E n g i n e e r e d  Magnetics D i v  is ion  
13041 Cerise A v e n u e  
H a w t h o r n e ,  C a l i f o r n i a  
FOR 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
MARSHALL SPACE FLIGHT CENTER 
HUNTSVILLE, ALABAMA 
https://ntrs.nasa.gov/search.jsp?R=19680012350 2020-03-12T09:07:13+00:00Z
TABLE OF C 0 N " S  
PAGE NO. 
ABSTRACT 
PREFACE 
I .  INTRODUCTION. 
11. WORK ACCOMPLISHED: THIS REPORT PERIOD. 
iii 
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3 
111. WORK PLANNED: NEXT MONTHLY REPORTING PERIOD. 19 
ii 
1. ' 
ABSTRACT 
This is  t h e  F i r s t  Q u a r t e r l y  Progress  Report f o r  Engineered 
Magnetics '  Applied Research and F e a s i b i l i t y  s t u d i e s ,  Ex- 
per imenta l  I n v e s t i g a t i o n s ,  And Conceptual O r  Prel iminary 
Design Engineering Applicable To I n v e r t e r s  For Motors. This 
r e p o r t  d e s c r i b e s  t h e  accomplishments achieved during t h e  
per iod  from June 2 2 ,  1 9 6 7  t o  September 25 ,  1967.  Information 
concerning motor s p e c i f i c a t i o n ,  motor c o n t r o l ,  I n v e r t e r  
breadboard des ign ,  and Inve r t e r  breadboard f a b r i c a t i o n  and 
t e s t i n g  is  presented  here in .  
8 iii 
PREFACE 
The National Aeronautics and space Administration Contract 
Number NAS8-20832, Applied Research and Feasibility Studies, 
Experimental Investigations and Conceptual or Preliminary 
Design Engineering Applicable To Inverters For Motors 
Program, was awarded to the Engineered Magnetics Division 
of Gulton Industries, Inc., on June 2 2 ,  1967. 
This is the First Quarterly Progress Report pertaining to 
the Engineered Magnetics Applied Research and Feasibility 
Studies of Inverters fo r  Motors Program, presenting the 
progress of the program from June 22, 1967 to September 25, 
1967. This report contains a review of t h e  technical in- 
formation which has guided the decisions and accomplish- 
ments for this period. 
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I. INTRODUCTION 
This  is t h e  F i r s t  Q u a r t e r l y  Progress  Report f o r  
Engineered Magnetics' Applied Research And Fea- 
s i b i l i t y  S tud ie s ,  Experimental I n v e s t i g a t i o n s ,  
And Conceptual O r  Prel iminary Design Engineering 
Applicable  To I n v e r t e r s  For Motors. ( h e r e i n  
a f t e r  r e f e r r e d  t o  i n  t h e  report body a s  Applied 
Research And F e a s i b i l i t y  S tudies  O f  I n v e r t e r s  For 
Motors Program.) 
The a u t h o r i t y  t o  proceed f o r  t h i s  s tudy  program 
i s  contained i n  NASA Cont rac t  No. NAS8-20832, 
da t ed  June 2 2 ,  1967. 
The s t u d y  program o b j e c t i v e s  are t o  advance i n  t h e  
areas of des ign ,  e f f i c i e n c y ,  l i f e  expectancy, re- 
l i a b i l i t y ,  and m o t o r  performance c h a r a c t e r i s t i c s  of 
i n v e r t e r s  f o r  space v e h i c l e  a p p l i c a t i o n .  
This  s tudy  program s h a l l  endeavor t o  advance tech- 
nology i n  t h e  f i e l d  of power condi t ion ing  w i t h  
improved design concepts and techniques .  
The Applied Research And F e a s i b i l i t y  S tud ie s  Of 
I n v e r t e r s  For Motors Program w i l l  be based on in- 
formation obtained from Engineered Magnetics 
I n v e r t e r s  For Motors Study Program conducted per  
NASA Cont rac t  No. NAS8-18013. 
-2- 
11. WORK ACCOMPLISHED: rFHIS REPORT PERIOD 
A. MOTOR SPECIFICATION. 
A procurement s p e c i f i c a t i o n  f o r  a 3 phase induc t ion  
motor w a s  prepared. A 3 phase induct ion  motor w a s  
ordered t o  t h i s  s p e c i f i c a t i o n .  The motor has  a 
r a t i n g  of 100 watts output  a d  opera t e s  on an i n p u t  
of 400 H z .  The motor is  designed w i t h  b i f i l a r  
windings t o  permit  ope ra t ion  w i t h  t h e  s i x  phase,  
h a l f  wave I n v e r t e r  shown i n  Figure 1. An addi-  
t i o n a l  motor f i e l d  housing ( s t a t o r )  assembly w a s  
a lso ordered.  One s ta tor  c o n s i s t s  of convent iona l  
i r o n  (14 m i l  M - 1 9  s i l i c o n  s t e e l ) ,  t h e  o t h e r  s ta tor  
u t i l i z e s  a high n icke l  material (Allegheney Ludlum 
4750, 7 m i l  l amina t ion) .  Motor operq t ion  w i t h  each 
s ta tor  w i l l  be ana l ized  t o  determine, emper ica l ly  
what improvement may be  obtained when a material 
w i t h  lower co re  loss i s  used .  The motor assemblies 
are scheduled t o  be d e l i v e r e d  a t  Engineered Magnetics 
i n  December, 1967. 
The motors procured f o r  t h e  I n v e r t e r s  For Motors 
Study Program (NASA Con t rac t  N o .  NAS8-18013) w i l l  
be u t i l i z e d  u n t i l  t h e  3 phase induc t ion  motor is 
rece ived  a t  Engineered Magnetics.  
B, MOTOR VOLTAGE CONTROL 
Two methods of motor vo l t age  c o n t r o l  being cons idered  
are desc r ibed  below. 
1. Method 1. 
This method c o n s i s t s  of c o n t r o l l i n g  t h e  pulse-  
wjdth modulation of t h e  quasi-square wave v o l t a g e  
as it is appl ied  t o  t h e  motor. The fo l lowing  
vo l t age  wave-shape is  eva lua ted .  
-3- 
X 
H 
VI 
d 
w c: 
3 
0 
H 
r4 
The harmonic con ton t  of th l r  wavoshapo is  ova lua ted  by por- 
forming a Four i e r  Analys i r .  
wavo and aXi8 symmetry tho i n t o g r a t i o n  is porformod from Oo 
Sinco  tho wavoohapa ha8 half-  
t o  goo. 
7s0+ h 
, n=l,3,5--- Thoroforo, e ( t ) =  4v [ s i n  nx dx + 1 s i n  nx dx]  
4 5 O -  h 7 5 O - A  O C A  L 15O 
1 is a8 de f ined  i n  tho wav06hapa i l l u 6 t r a t i o n .  3 i e  tho 
on-to-of f t h o ,  
convont iona l  quaei-squaro wavo. 
Whon x=1So  tho wa~eshapo dogeneratus  i n t o  the 
Performing the  i n d i c a t e d  i n t o g r a t i o n  results i n  
2 L 
By uming tho i d o n t i t y  com (x f y)  - COB x COB y 7 s i n  x 6 i n  y, 
8 V  the  oxpromsion bocomos o n ( t ) = -  ( 6 i n  n 45O Bin n A +  e i n  n 75O s i n  n 
A ) , and substituting numeral 1,3,5, --- for n, r o s u l t s  i n  
= I 7  -@Y(.7071 s i n k +  -96593 s i n k ) =  4.26VminX. +l 
e = 0-  
e = 0 . 2 2 8 V  sin SA. 
a = 0.163 e i n  7A.  
3 
5 
7 
I- eV (min n 4 5 O  + sin n 75O) s i n  n k .  
On 77 
Tho60 curv.8 are shown in Figuro 2. 
The sam procoduro whon appl iod  t o  a t w o  pulmo por l 8 O o  wave- 
ahapo i 6  am shown below, 
-5- 
1. 
I 
I 
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0 
This  r e s u l t s  i n  en = 8v s i n  n 60 s i n  nX: then  by s u b s t i t u t i o n  
mr 
e 
e - 0.20 V s i n  11X. These cu rves  are shown i n  F igu re  3. 
F igu res  2 and 3 show t h a t  t h e  fundamental component (el curve)  
is approximately l i nea r  w i t h  the pulse-width,  and t h a t  t h e  number 
of pulses-per-cycle g r e a t l y  e f f e c t s  t h e  ampli tude of t h e  harmonics 
generated.  F igu re  2 has  fewer 5 t h  and 7 th  harmonics than  F igu re  3 ,  
b u t  i n  F igu re  2 t h e  h igher  harmonics have inc reased .  
= 2.205 V sinX, e5 = .442 V s i n  5 X ,  e7 = .316 V s i n  7 X ,  and 1 
11 - 
2. Method 2 .  
The o t h e r  method be ing  eva lua ted  f o r  c o n t r o l l i n g  t h e  v o l t a g e  t h a t  
is a p p l i e d  t o  t h e  motor, is  t o  i n s e r t  a swi tch ing  r e g u l a t o r  i n  t h e  
power l i n e  and t h u s  have direct  c o n t r o l  of t h e  a p p l i e d  vo l t age .  
The r e l a t i v e  advantages of  t h e  t w o  methods are determined by t h e  
e f f e c t  of  t h e  chopped wave on motor performance. 
3. Expanded Pu l se  Modulating Frequency. 
The F o u r i e r  Analys is  of 2 pulses per  180° (1/2 cyc le )  and 4 p u l s e s  
pe r  180 
procedure described above t h e  expres s ion  f o r  t h e  v a r i o u s  harnionics 
becomes 
0 
w a s  expended t o  inc lude  8 p u l s e s  per  180°. Using t h e  
e =  8 
nn 
( s i n  n 37.5' + s i n  n 52.5O + s i n  n 67.5O f n 
s i n  n 82.5O) s i n  nX. 
0 O ( h 5 7 . 5  . 
The cu rves  on F igu re  4 show t h e  v a r i a t i o n s  of harmonic ampli tude 
v e r s u s  lambda (I). As these curves  i n d i c a t e  t h e  p u l s e  modulating 
frequency should be a t  Least 24 t i m e s  t h e  l i n e  frequency.  
-7- 
1 
LITUDE VS L W m A  ( A )  9- FIGURE 4 .  HARMONIC 
C. INVERTER BREADBOARD. 
1. I n v e r t e r  Breadboard Design. 
An I n v e r t e r  breadboard w a s  fabricated t o  permit  
eva lua t ion  of motor-system performance a t  v a r i a b l e  
f r equenc ie s  and pulse wid ths .  
of t h i s  breadboard i s  t h a t  no t ransformers  are t o  be 
employed, either as ou tpu t  t ransformers  o r  d r i v e  
t ransformers .  The engineer ing  ske tch ,  F igu re  5,  
shows the I n v e r t e r  and i n v e r t e r  g a t i n g  of t he  r ing-  
t a i l e d  counter  f o r  gene ra t ing  the 3-phase s i g n a l s .  
Logic g a t i n g  f o r  motor r e v e r s a l  and pu l se  modulation 
i n p u t  is  also shown. This  power t r a n s i s t o r - d r i v e r  
arrangement w a s  u t i l i z e d  t o  d r i v e  the p r e s e n t l y  ’ 
a v a i l a b l e  3 phase motors wi thout  t h e  u s e  of d r i v e  
t ransformers .  
One of the requirements  
Since many d i f f e r e n t  i n p u t  v o l t a g e s  are requ i r ed  by 
the I n v e r t e r  breadboard, a s imple Converter  was b u i l t  
t o  gene ra t e  the +lo, t5,and +3 V o l t  inputs .  These 
c i r c u i t s  are a l l  referenced t o  ground. Addi t iona l  5 v o l t  
and 3 v o l t  ou tputs  a r e  genera ted  and r e fe renced  to the 
main I n v e r t e r  input  vol tage.  
shows t h e  conver te r  power supply that  w a s  b u i l t  
t o  f u r n i s h  the I n v e r t e r  i n p u t  vo l t ages .  N o t e  t h a t  
V3 and V4 are referenced  t o  V5. V5 is t h e  main power 
inpu t  t o  t h e  I n v e r t e r  
The diagram on Figure  6 
The c i r c u i t s  on F i g u r e  7 .are for s l i p  c o n t r o l  and pu l se  
w i d t h  c o n t r o l .  I n  t h i s  c i r c u i t  des ign  the two mono- 
s t a b l e  m i l t i - v i b r a t o r s  gene ra t e  pu l se s  of approximately 
150 microseconds. The diode  detectors w i t h  the  
o p e r a t i o n a l  ampl i f i e r  gene ra t e  a v o l t a g e  p ropor t iona l  
t o  the d i f f e r e n c e  of t h e  inpu t  f r equenc ie s .  A s  t h i s  is 
a c losed  loop feed-back arrangement,  motor s l i p  may be con- 
t r o l l e d  by the amplifier offset  c o n t r o l ,  The of fse t  c o n t r o l  
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8 
e 
e 
L 
r- 
d :p M c/) 
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I .  
I 
I 
8 
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J 
8 
8 
8 
8 
I 
8 
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8 
8 
L 
v o l t a g e  is appl ied  t o  t h e  d i f f e r e n t i a . 1  a m p l i f i e r  
(47, 48, and 49).  I n  t h i s  c i r c u i t  47 c o n t r o l s  t h e  
charging c u r r e n t  through C 1  and t h e  frequency of 
t h e  unijlunction oscillator 06. R3 sets t h e  minimum 
frequency of osci l la t ion (47 is  c u t  o f f ) ,  and R4 sets 
the maximum o s c i l l a t i n g  frequency (49 is  c u t  o f f ) .  
The t h r e e  b ina ry  d i v i d e r s  (FF3, 4, and 5) o p e r a t e  i n  
conjunct ion  wi th  the  p u l s e  width c o n t r o l  c i r c u i t  (FF6, 
410, and 011) t o  gene ra t e  t h e  p u l s e s  shown on Figure  4. 
When S3'(Figure 7) is  i n  the down p o s i t i o n  t h e  pu l se  
width modulation is n o t  synchronized t o  the motor 
frequency b u t  is approximately 8 . 5  KHz. 
The block diagram, F igu re  8, shows t h e  p r e s e n t  I n v e r t e r /  
motor system design. This system is designed f o r  
c o n s t a n t  s l i p - v a r i a b l e  power opera t ion .  The motor 
i n p u t  c u r r e n t  is set  by motor voltage c o n t r o l  Rg 
(Figure 7 ) .  When S2 and S3 are both  i n  the 'down' 
p o s i t i o n  t h e  motor w i l l  accelerate u n t i l  it is opera t ing  
a t  a f i x e d  s l ip .  I f  t h e  motor load  is i nc reased  t h e  
s l i p  detector c i r c u i t  w i l l  s ense  t h e  change i n  s l i p  and 
w i l l  decrease  t h e  o s c i l l a t o r  frequency. The osc i l l a to r  
frequency w i l l  be decreased u n t i l  the  motor is a g a i n  
running a t  a f ixed  s l i p  and the d e l i v e r e d  to rque  matches 
the load  requirement,  This system is the t y p e  r e q u i r e d  
fo r  t r a c t i o n  d r ive  a p p l i c a t i o n  w i t h  R5 func t ion ing  as 
the vehicle a c c e l e r a t o r  c o n t r o l ,  The speed and s l i p  
c o n t r o l  c i r c u i t s  can be used fo r  any system r e g a r d l e s s  
of s i ze ,  
des ign  change requi red  w i l l  be in the  I n v e r t e r  ou tpu t  
stages. 
The s l i p  c o n t r o l  c i r c u i t  w a s  eva lua ted  by supplying 
a n  audio  frequency t o  t h e  base of 42 and t h e n  measuring 
the  osci l la tor  output  f requency.  The f r equenc ie s  
I f  a l a rge?  motor is t o  be u t i l i z e d ,  the only  
2 . I n v e r t e r  Breadboard Tests. 
-14- 
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1 
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I 
1 r - - - - - - - - - -  
t- u 
a 
-15- 
measured are 6 times the motor i n p u t  l i n e  f requencies  
as requi red  by t h e  r ing  counter.  
are t abu la t ed  as f o l l m s t  
The t e s t  r e s u l t s  
15 18 
1004 
500 
SLIP CONTROL EVALUATION 
1564 
1078 
606 
LNPUT I 
~ - __ 
509 
423 
339 
261 
180 
101 
bLIP (Hz) 
(400 H z  reference)  
7.3 
3.5 
4.65 
7.7 
12.3 
17.7 
The slip would remain at a more constant level if the 
DC loop gain were increased. 
When the motor is driven b y  a s i g n a l  s i m i l a r  t o  tha t  
shown i n  F igure  4 there is no torque  developed u n t i l  
the  waveform very  near ly  approaches a quasi-square 
wave. The vo l t age  c o n t r o l  appears  t o  be e f f e c t i v e  when 
a high pu l se  width frequency of approximately 8.5 KHz 
is u t i l i z e d .  This lack of t o r q u e  is apparent ly  caused 
by the r e s e t t i n g  of t he  motor co re  t o  zero during the  
Ilzero voltagell i n t e r v a l  which occurs  i n  t h e  per iod 
between pulses .  When t h e  f i e l d  c u r r e n t  drops t o  
zero ,  a negat ive  cu r ren t  pu l se  is  generated i n  the 
rotor c i r c u i t  r e s u l t i n g  i n  no n e t  r o t a t i o n a l  to rque  
t h a t  can be meaaured. 
-16- 
Figure  9 i l l u s t r a t e s  a t r a n s d u c t o r  voltage p u l s e  width 
c o n t r o l l e r  t h a t  func t ions  as a c u r r e n t  monitor  t o  
l i m i t  t h e  i n p u t  c u r r e n t  t o  a va lue  se t  by R2 ,  
( t h e  prev ious ly  designed Pu l se  Width Cont ro l  C i r c u i t  
is s h m n  as p a r t  of Figure  7.) 
veloped a c r o s s  R2 t h a t  is p r o p o r t i o n a l  t o  the  main 
i n p u t  c u r r e n t .  The 500 t u r n  windings of T 1  and T2 
suppor t  t h e  square  wave s i g n a l  s u p p l i e d  from a winding 
on t h e  conve r t e r  t ransformer.  
i n  t he  one t u r n  secondaries  w i l l  b i a s  t he  c o r e s  
so t h a t  t h e y  w i l l  s a t u r a t e  for  p a r t  of t h e  cyc le .  
DC v o l t a g e  developed across resistor R 1  is sampled 
and compared wi th  a r e f e r e n c e  v o l t a g e  by emitter- 
coupled d i f f e r e n t i a l  a m p l i f i e r  01 and Q2. WIWA ui 
conducts  03 w i l l  d e l i v e r  a charging c u r r e n t  t o  
un i junc t ion  o s c i l l a t o r  c a p a c i t o r  C 2 ,  and z a e  
osci l la tor  w i l l  opera te  a t  a frequency which will 
produce t h e  waveform shuwn i n  F igure  4. 
quasi-square wave, F igure  4,  duty c y c l e  (A )  w i l l  be 
so designed t h a t  m a x i m u m  c u r r e n t  drawn by the  I n v e r t e r  
motor combination w i l l  n o t  exceed the va lue  set  by 
c u r r e n t  c o n t r o l  r e s i s t o r  R2. A minimum Value  of 
5 amperes DC c u r r e n t  l i m i t i n g  can be s e l e c t e d  w i t h  
the p resen t  c i r c u i t  . 
A v o l t a g e  is de- 
A DC c u r r e n t  f luwing 
I. 
The s tepped 
Due t o  s e v e r a l  t r a n s i s t o r  f a i l u r e s  i n  t h e  I n v e r t e r  
s e c t i o n ,  t h e  output  t r a n s i s t o r s  were changed from 
2N3771 t o  RCA TA2669. The d r i v e r  t r a n s i s t o r s  were 
changed t o  a higher  v o l t a g e  type  (2N3585). Bread- 
board opera t ion  w i t h  these t r a n s i s t o r s  w i l l  be 
a n a l i z e d  and d iscussed  a t  a later d a t e .  
-17- 
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111. WORK PLANNED : NEXT REPORTING PERIOD. 
Inverter/motor t e s t s  w i l l  be conducted t o  obtain  
torque/speed curves showing the  effect of current  
l i m i t i n g .  Performance data  and t h e  torque/speed 
curves w i l l  be evaluated.  
-19- 


Applied research and feasibility studies, experimental investigations and conceptual or preliminary design engineering applicable to inverters for motors program  Quarterly progress report, 22 Jun. - 25 Sep. 1967

Applied research and feasibility studies, experimental investigations and conceptual or preliminary design engineering applicable to inverters for motors program Quarterly progress report, period ending Jun. 25, 1968

Abstract

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