V ol. 15
N o. 3
A ugust 2002
CHIN ES E J OU RN A L O F A ER O N A U T ICS
Implementation and Study of a Novel Doubly Salient
Structure Starter / Generator System
L IU Chuang , ZHOU Bo, YAN Yang -guang
( A ero-p ow er S ci-tech Center , N anj i ng University of A eronautics and A str onaut ics,
N anj ing 210016, China )
Abstract:
A new t ype of double salient start er/ gener ator is presented, which can be used in air-
cra ft L ow V oltag e D ir ect Curr ent ( L VD C) , V ariable Speed Constant Fr equency ( V SCF) and Hig h
V o ltag e Dir ect Curr ent ( HV DC ) sy stems . T he o per ational theo ry o f the moto r and gener ator is
analyzed, and cor responding co ntro l str ategies ar e g iv en. A n 18kW pro to type has been implemented to ver ify the sy stem per for mance . I t is show n that the D SM S / G system po ssesses simple str uctur e, hig h efficiency and flex ible co ntro l . It is a ppro pria te to be used fo r aircr aft application .
Key words : double salient mo tor ; star ter / g ener ato r ; fielding w inding ; per manent magnetic
一种新型的双 凸 极起 动/ 发 电 机的 研究 及 实践. 刘 闯, 周 波, 严仰 光. 中 国航 空学 报 ( 英 文 版) ,
2002, 15( 3) : 150- 155.
摘
要: 介绍 一种可以适应于航 空低压直流、变速恒频、高压直流电气系 统的新型双 凸极起动/ 发
电 机系统, 并对其电 动及发电 机理进行了 理论研究, 给出起 动/ 发电 机的相应控 制策略, 在此基 础
上 研制了 18kW 样机并进行了原理 试验研究, 试 验结果表明: 双凸极电机起动/ 发电系统的 方案具
有 结构简单、
可靠及控制方便等优点, 适合作航空用起动/ 发电机 。
关 键词: 双凸极电机; 起动/ 发电; 电磁式; 永磁式
文 章编号: 1000-9361( 2002) 03-0150-05
中图分类号: T M 352
文献标识码: A
T he aircr aft int egral st art er / gener at or system
oper at es no t only as a st art er but also as a g enera-
T radit ionally , t he mot ors used as a st art er /
g enerat or include Brush DC M ot or ( BDCM ) , Per-
to r acco rding to t he reversible operatio n of elect ric
machines. W hen operat ing as an eng ine st ar ter,
m anent M agnet Sy nchr ono us M ot or ( P MSM ) , Induct io n\ M ot or ( IM ) , Sw it ched Rel uctance M ot or
( SRM ) and so on . With f ast developm ent of pow er
t he mot or produces a t orque t o spin the engine up
t o its lig ht -o ff speed. F ollo wing t he lig ht -of f
speed , it continues t o produce t he to rque and assist s t he eng ine in accelerat ing t o t he idle speed.
When t he eng ine is running , t he elect ric machine
oper at es as a g enerat or to supply vehicle loads. In
shor t, the st art er / generat or system l essens a special st art er and results in a low er syst em w eight
and higher sy st em reliability , and it is a key t echno logy in t he M ore Elect ric Aircraft ( M EA ) f or
pr oviding t he eng ine st art , and po w er t o elect ric
dr iv en pum p and ot her elect rical loads and act uato rs . T heref ore , it is a subst ant ial aspect o f ad[ 1-3]
vance in t he aircraf t po wer supply pr ogress .
Received date: 2001-10-24; Revision recei ved dat e: 2002-4-18
Foundati on it em: Q in glan En gineer Fou ndat ion of Jiangs u Province
A rt icl e U R L: ht t p: / / ww w . hk xb. net. cn/ cja/ 2002/ 03/ 0150/
elect ro nics and m icro elect ro nics, t he double salient
m ot or ( DSM ) is a novel t ype AC driver w hich w as
f irst put f orw ard by T . A . L ipo in 1990' s. A lot of
l it erat ure on DSM and it s cont ro l syst em ar e report ed in Am erica, Europe and China. T he m ajor
advant ages of DSM ar e sum marized as hig h ef ficiency , hig h densit y, high to rque/ current rat io ,
[ 4～6]
. According to dif ferf lexible cont ro l and so on
ent ex cit at ion pat t erns it can be divided int o t hr ee
t y pes: permanent , f ielding w indings and hybrid
m ot ors . It po ssesses sim ple , rugg ed st ruct ur e and
is used in hig h temperature, high speed o ccasions
due t o no w indings and per manent magnet on t he
Implemen tat ion and St udy of a N ovel Doubl y S al ient
S tru ct ure S tart er / G enerat or S yst em
A ugus t 2002
rot or . DSM has t he po tent ial in aer ospace applicatio ns .
T his paper present s a new t ype st art er/ gener ato r sy st em —— Doubl e Salient St art er / Generat or
( DSS / G ) , and analyzes it s double -f unct ion operatio nal t heory , sy st em design , contr ol st rateg ies
and ex periment al results.
1
DS Start er / Generator Operational T heory
Fig . 1 show s the cross sect ion of a t hree-
phase, 6/ 4-po le DSP M. It can be not ed t hat t he
st ruct ure of DSPM is similar to t hat of SRM ; tw o
pieces of P M are buried in t he stat or , and int ro duced int o t he main fl ux path o f the stat or w inding s. T he stat or pole arc is set t o be / 6 mechanical radians. As config ured , the airg ap reluct ance
seen by the PM ex cit ation is invariant o f t he rot or
· 151·
T he f lux linkag e
is composed of the PM
f lux linkage m and t he arm ature react ion f lux
l inkage ( L i) . T he elect rical pow er entering any of
t he w inding s is, neglecting ohmic and iron losses,
Pe =
d
dt
1 2
Li +
2
1 2 L
i r+ i
2
m
r
!r ( 2)
Hence, t he to rque can be w ritt en as t he sum
[ 5, 6]
.
o f t wo component s
1 2 L
T = 2i r + i
m
r
= Tr + T m
( 3)
T he f ollo wing f eat ures o f t he DSPM are revealed t hrough f rontal analysis: T he ar mat ure reaction f ield energy W f , which is to be recovered
dur ing current co mmut atio n, is very small because
o f t he small value of t he st at or induct ance . T heref ore , the energy co nv ersion rat io is v ery hig h . T he
t ot al t orque of the mot or co nsist s of tw o component s, the react ion to rque T m and t he reluctance
t or que T r according t o Eq. ( 3) . Because of t he t riangular-shaped variat io n o f the st at or w inding induct ance, T r has a zero average value if t he current
am plit ude is kept const ant during one st ro ke as
show n in t he m iddl e of F ig . 2. on , off ar e t urning o n and t urning -o ff angles of pow er sw itches re-
Fig. 1 T he cr oss sect ion o f a three -phase,
6/ 4-pole DSPM
po sit ion if f ring ing is neg ligibl e. T heref ore, t here
is essent ially no cogg ing t orque produced at no load . A linear v ar iat ion of the phase fl ux linkag e
and the inductance is induced in each o f t he stat or
w inding s as show n in t he upper o f F ig. 2. Homo plastically, the phase w indings f lux of double
salient elect ric mot or ( DSEM ) is provided by f ielding w indings in t he st at or inst ead o f t w o pieces of
PM . T he t orque ex pression derived below is based
on a sim plif ied linear m odel f or the purpose of il lust rat io n. T he v ariat ion o f w inding induct ance
and flux linkag e of an act ive phase are assum ed t o
be piece-w ise l inear and spat ial ly dependent only.
T he term inal volt age equat ion f or a phase w inding
is then
d m
d
di
dL
u = Ri + dt = L dt + i dt + dt
( 1)
Fig. 2 Illustr ation of o per ating pr inciples o f DSPM
spect ively. T he react ion t or que T m , w hich is t he
dominant t orque com ponent , can be produced by
apply ing eit her a posit ive current t o a phase w inding w hen its f lux l inkage is incr easing ( em > 0) o r a
negat ive current w hen t he f lux linkage is decreasing ( em < 0) . It can output mechanical energy at
t w o quadrant s of t he m agnet izat ion curv e, w hich
m akes t he volume o f t he mo to r sm aller. T he v alue
LIU C huang , ZHO U Bo , Y A N Yang -guang
· 152·
of t he t orque is adjust ed t o the t hr esho ld o f t he
CJA
phase current and ot her param et ers such as t urning -on angle and t urning -off ang le. It is also real -
f iel ding w inding flo w current t o pro vide f ielding
ener gy . T hree EM F are ex por ted fr om t hree phase
f lux linkage varying w it h r ot ating of t he ro to r, and
ized by one-beating or tw o -beating in each cycl e.
DC volt age is produced t hrough diode rect ifier.
T hen o perat io nal mo des bet w een mot oring and re-
Regulation of DC vo ltag e is realized thro ug h regu-
generat ing brakes are alt er ed t hrough v ar ying t he
direct ion of t he phase current . Fo ur quadrant s op-
lat ing f ielding winding cur rent by generat or contr ol
unit ( GCU ) .
er at ion is readily achieved by changing the sequence of co nduct io n and t he polarit y of t he stat or
currents.
T he do uble salient st ar ter/ g enerat or is constr uct ed in t w o cascades , an excit er , main st art er /
g enerat or and ot her accessor ies are packaged in
T he to rque of Do uble Salient Elect ric M ot or
( DSEM ) is co nt rol led thro ug h not only regulat ing
config urat ion o f DSS/ G. It is sho wn in F ig . 4.
M ain mot or is a 12/ 8-po le DSEM , t he st ruct ures
t he phase current but also v arying t he int ensity of
fielding f lux linkage. T heref ore, DSEM has a f ea-
o f it s st at or and rot or are salient poles . Co ncent rat ed phase and f iel ding w inding s are co iled in t he
ture o f flex ible contr ol and oper at ion o ver a w ide
speed range .
st ato r. Each t w o f aced winding o f f our st at or t eet h
is linked in series; t hr ee phase w inding s ar e con-
2
T he Configurat ion of DS
St art er / Generat or
nect ed w ith star -shape. T he cr oss sect ion of t he
m ain generat or is show n as F ig. 5. T he pole ar c is
a half of t he stat or pole int erv al ; t he st at o r pole
DSM st art er / generat or sy st em co nsist s of a
st art er / gener at or , pow er co nv ert er , digit al contr oller , g enerat or cont ro l unit ( GCU ) and ot her
adjuvant par ts such as curr ent sensor and po sit ion
sensor , as sho wn in F ig. 3.
F ig . 4 Co nfigur atio n of DS Star ter / G ener ato r
F ig . 3 Schematic diag r am of DS
St arter / G enerat or System
During t he st art ing process, the sto rage bat tery po w ers up f ielding w inding s and est ablishes
fielding magnet energy . T he diff er ent sw it ches of
t he pow er convert er are turned o n or of f according
arc is set t o be / 12 mechanical radians. T heref ore, t he gap r eluct ance, seen by fielding excit a-
t o t he posit ion sig nal, and t he current f low s in cor -
t ion, is const ant if f ringing is neg ligible. A phase
responding phase windings, and the st ar ter pro -
arm ature inductance varies w it h t he overlop bet w een the st at or and rot or , and t he r ot or pole ar c
duces a f ixed direct t orque and spins t he eng ine up
t o w ork. All sw it ches of t he pow er convert er are
t urned of f dur ing t he g enerat ing process. Engine
revolv es the st art er / generat or in hig h speed , then
Fig. 5 T he cr oss sect ion o f main S/ G moto r
is select ed to be slight ly great er t han t he st at or
pole arc t o allow for curr ent reversal .
T he exciter gener at or is also a 12/ 8-pole con-
Implemen tat ion and St udy of a N ovel Doubl y S al ient
S tru ct ure S tart er / G enerat or S yst em
A ugus t 2002
fig urat ion. F our Sm Co m agnet s are buried in t he
st at or inst ead of f ielding w indings . T he sizes of t he
excit er g enerato r are sim ilar to t hat o f t he main
mot o r. Fig . 6 show s t he cr oss sect ion of PM ex cit er g enerat or . T he excit er g enerat or pr ovides
elect ric ener gy f or fielding windings t o est ablish
mag net ic f ield w it ho ut bat t ery . T he st ruct ures of
t he main m ot or and ex cit er generat or are desig ned
by Finite Element Analysis m et hod . T he part paramet ers o f a 18kW pro to ty pe are prov ide in T able
1.
· 153·
t or speed, and t he phase current chopping t imes
are lessened because t he back EMF rest rains t he
phase current t o rise. T he value of the phase current co nt inuous is al most kept co nstant . When t he
back EM F of phase w inding is equal t o t he bat t er y
v olt age , t he chopping t im e is zero ; the phase current can not be enhanced sequent ial ly alt hough
pow er sw it ches are t urned on. T he st ar ter ent er s
t he const ant pow er start ing st ag e and t he average
t or que begins t o drop. Once t he engine reaches it s
idle speed, t he st art ing pro cess is over. Ot herw ise , t he fielding cur rent is l essened to improve
t he syst em speed unt il the engine reaches it s idle
speed.
F ig. 7 sho ws t he ex periment al phase current
w ave and cont rol sig nal of t he st art er at 500r / m in
speed w her e t he phase current is a 120°quasisquare w avefor m. At high speed, t he current can-
F ig . 6 T he cr oss sectio n o f PM excit er g ener ato r
Table 1 Basic size of main generator and exciter
not be m aint ained const ant due t o t he excessive
EM F . In this case, t he cur rent peaks in the f irst
A ir gap
Leng th
half st roke drop rapidly due t o a w ide speed range.
M
OD / mm ID/ mm O D / m m
1J21
180
116. 6
116
/ mm
0. 3
/m m
160
E
D41
0. 3
18
T he exper im ent al curr ent w ave is show n in Fig. 8.
So turning -on angl e on and t urning -o ff ang le off are
M at erial
St at or
146
St at or
99
R ot or
98
r equired to opt imize w it h variat io n of speed .
3
Control Strat egy of St arter/ Generat or
3. 1 Starting process
According t o engine operation, t he st art ing
pr ocess is divided into t hree stag es, sof t st art ing
st age , const ant t orque st art ing st age and const ant
po w er st art ing st ag e.
At init iative st ar ting st age, a small st art ing
t orque is requested t o eliminate the clearance of
gearbox , and l essen impact t o eng ine . T he t orque
is limit ed by chopping phase windings current under
Fig . 7 Ex per imental w ave o f lo w speed mo to ring
F ig. 9 show s t hat the curves of the start ing
t or que are t est ed bet ween the f ielding w inding cur-
constant f iel ding current . T he cho pping
t hr esho ld of an 18 kW st art er / generat or prot ot ype
is set 200A at t he so ft st art ing st ag e. T he t hresh-
rent and upper t hreshold of t he phase w inding current . T he magnetizat ion curv e is lo cat ed at satura-
old of the phase current is set 600A quickl y aft er eliminat ion of t he gearbox clearance, t he t orque is
st arting t orque by incr easing t he upper threshol d
o f the phase current inst ead of f ielding curr ent .
increased quickly up to m ax imum t o accelerat e t he
eng ine, and t he start er ent ers the co nstant t orque
F ig. 10 sho w s t or que/ speed char act er ist ics of t he
st arting process wit h 5kg · m max im um t orque .
st art ing st ag e. T he back EMF o f phase w indings
T he out put t or que is almost const ant , w hich is
m aint ained by chopping dur ing 0 ～ 2000r/ m in
increases mo re and more w it h im pro vement of ro -
t ion w hen i f > 10A. It is ef fective to improv e t he
· 154·
LIU C huang , ZHO U Bo , Y A N Yang -guang
CJA
speed range. On t he ot her hand, t he out put t orque
cy t riang le wav ef orm . Regulat ion of field w inding
dr ops and o ut put pow er is nearly const ant dur ing
2000～4000r / min.
current if can be im plemented t hrough variat io n of
t he duty ratio . A st eady out put DC volt age is car r ied o ut a cco rdingly under differ ent speeds and loads. T he
dynamic per for mance
o f t he out put volt age w ill be
specially intr oduced in ano ther paper .
Fig. 8 Ex per imental w ave o f high speed mo tor ing
F ig . 11 Schematic diag ram o f gener ator system
F ig. 12 show s generat ing ex perimental w aves
o f three phases vol tag e, and AC vo lt ag es are rect i-
F ig . 9 T or que v ersus t hreshold o f phase curr ent and i f
Fig. 12
Exper imental wav e of thr ee phase v oltag e
f ied int o DC v olt age fo r load. Characterist ics of DC
v olt age/ speed ar e sho wn in F ig. 13 under the condit ion of I o = 0, 5, 10A ; a favo rable linear relation
Fig . 10 T or que/ speed char acteristic of star ting pro cess
3. 2 Generating process
Af ter t he st art ing pro cess , DSEM w orks as a
generat or . T hree AC elect ric ener gy f low s t hro ug h
t he rect if ier t o be convert ed int o DC elect ric ener gy . Generat or co nt rol relay ( GCR) is closed and
t he ex cit er g enerato r ex por ts elect ric energ y t o
fielding w inding of t he m ain g enerato r. Out put
volt ag e of the g ener ato r is reg ul at ed thro ug h chopping the f ielding cur rent by GCU .
Fig . 11 show s a block diag ram o f GCU , w hich
includes t he vol tag e senso r , f ielding cur rent sensor , pul sed widt h modulat ion ( P WM ) , pow er am plif ier and pro tection part s . T he bus volt age of
POR det ected by t he sensor is co mpared w ith t he
reference volt ag e. PWM signal is produced betw een a changing error sig nal and a fix ing f requen-
is obt ained bet w een t he output volt ag e and speed
because the back EM F is pro port ional t o t he variet y rat io of phase flux linkage . F ig . 14 show s t he
curves of the out put vo ltag e v ersus if under no
l oad. It is interest ing t o no tice t hat a lit t le eff ect
o n volt ag e is accom panied w ith saturat ion, w hen i f
is exceeding 6A . T he contr ol characterist ic of t he
g enerat or is show n in Fig . 15. Generat ing contr ol
perfo rmance at big f ielding curr ent is inf erior t o
t hat at sm al l f iel ding current , an 18kW rated o ut put po wer is obtained under condit ion o f 4200
r / min speed, if = 13A , and mor e generat ing pow er
is produced at high speed.
4
Conclus ions
T his paper has laid t he theoret ical and ex perim ent al f oundat ion f or a new ty pe double salient
Implemen tat ion and St udy of a N ovel Doubl y S al ient
S tru ct ure S tart er / G enerat or S yst em
A ugus t 2002
· 155·
GCU . Furt herm ore, pr ot ectio n f unction is carried
o ut t hrough cutt ing betw een ex cit er and f ielding
w indings. And t he system can realize self -generat ing operat ion w it ho ut ex t er nal po w er supply . Neit her po wer convert er no r po sit ion sensor is required in t he generat ing operat ion , w hich r esult s in
high rel iability .
F ig . 13 O ut put v oltag e ver sus speed
T he br ushl ess integ ral st art er/ generat or is designed f or L VDC syst em . Compared t o o ther t ypes
o f st arter / generat ors it is sho wn t hat it possesses
simpler st ruct ure and higher reliabilit y. And it
m ay be also used in hig h v olt age direct current
( HVDC ) and v ariable speed const ant frequency
( VSCF ) in t he f ut ure.
References
Fig . 14 O utput vo ltag e ver sus ex citing curr ent
[ 1]
R ich ter E, et al . Th e int egral st ar ter/ gen erat or development
progr ess [ J ] . IE EE A ES S yst em s M agazine, 1996, ( 10 ) : 17
I f under no lo ad
- 23.
[ 2]
M acM inn S R, Jones W D . A very high speed sw it ched relu ct an ce s t art er / generator f or aircraf t engine applicat ion
[ A ] . In: Proc N A EC ON ' 89[ C ] . 1989, 1759- 1764.
[ 3]
Ferreira C A , Jones S R , et al . D et ailed des ign of a 30-kW
s w itched reluctance st art er / gen erat or sys t em f or a gas t urbine engin e appli cat ion [ J] . IE EE IA , 1995, 31 ( 3 ) : 553 561.
[ 4]
Blaabjer g F.
N ew advanced cont rol met hods f or doub ly
s al ient perm anent m agn et m otor[ J ] . IEEE IA , 1995, 31( 2) :
Fig . 15 Output pow er v ersus exciting cur rent I f
mot o r start er/ g enerato r system . T he design and
222- 230.
[ 5]
m ot or f or adj ust ab le s peed driver [ J] . Elect ric M achines and
co nt rol str at egies o f t his system have also been im plemented alt hough m uch r esearch remains ahead
t o fully assess the po tential of such sy st ems . It is
evident t hat t his DS st ar ter/ g enerat or possesses
t he fol low ing adv ant ages:
T he main st art er / g enerato r
has simpl e,
rugg ed st ruct ur e and hig h speed capability o w ing
t o no permanent magnet s and no windings on t he
rot or .
T he st art er / g enerato r possesses pow er densit y
and high ef ficiency , making VA r at ing o f t he po w er co nv ert er smaller as well as the m ot or.
T he conf ig ur ation of the mot or is constructed
in t w o cascades. It is convenient t o achieve st art ing
and g enerating funct ions. T he excit er off ers electr ic ener gy for fielding windings of t he m ain gener ato r . T he qualit y of DC volt ag e is r eg ulat ed by
Y ue F, Lipo T A . A n ew doubl y salient permanen t magn et
Pow er Sys t ems , 1994, 22 ( 2) : 258- 270.
[ 6]
Y ue F, Liao F L, Li po T A .
A novel permanent magn et
m ot or w it h doubl y salien t st ruct ur e[ J] . IEEE Tr ans acti on s
on Indus tr y A ppl ication s, 1995, 31( 5) : 1069- 1078.
[ 7]
Ch eng M , Zh ou E. A nalysis and cont rol of novel s plit -w inding doubly s al ient permanen t mag net mot or f or adjus table
s peed drive[ J ] . Science in Ch ina ( s eries E ) , 2001, 44( 4) : 353
- 364.
Biography:
LIU Chuang Bor n in 1973, he r eceived
M . S. and Ph. D. fr om N anjing U niver sity of A er onautics and A str onautics in
1997 and 2000, respectively . N ow he is a
tea cher in the A uto mation Eng ineering
Co llege. His main resear ch int erests encompass po wer electr onic, electr ical machines contr ol aerial electr ical and indust rial contr ol system .
T el: ( 025) 4892056, 4891796, E-mail: l. chuang @ nuaa .
edu. cn