Ad ances in Elec ical and Elec onic Enginee ing
86
SINGLE PHASE CURRENT-SOURCE ACTIVE RECTIFIER FOR TRACTION:
CONTROL SYSTEM DESIGN AND PRACTICAL PROBLEMS
J. Michalik, J. Molna , Z. Pe ou ka
Uni e si y o Wes Bohemia, Facul y o Elec ical Enginee ing, Depa men o Elec omechanics and Powe elec onics,
Plzen, Czech Republic
e-mail:jmichali@ke .zcu.cz, [email p o ec ed].cz, pe ou [email protected] g
Summa y
This esea ch has been mo i a ed by indus ial demand o single phase cu en -sou ce ac i e ec i ie dedica ed
o econs uc ion o olde ypes o dc machine locomo i es. This pape p esen s con e e s con ol s uc u e design and
simula ions. The p oposed con e e con ol is based on he ma hema ical model and due o possible in e ac ion wi h ailway
signaling and equi ed low swi ching equency employs synch onous PWM. The simula ion esul s a e e i ied by
expe imen al es s pe o med on designed labo a o y p o o ype o powe o 7kVA.
1. INTRODUCTION
This esea ch has been mo i a ed by indus ial
demand o design o single phase cu en -sou ce
ac i e ec i ie (CSAR) dedica ed o econs uc ion
o olde ypes o dc machine locomo i es. Con e e
mus be able o ope a e on bo h olley ol ages:
25kV/50 Hz and 15kV/16  Hz. The goal o ou
esea ch is he ealiza ion o he low powe (7 kVA)
labo a o y p o o ype o his con e e .
De elopmen was di ided in o h ee s ages:
con ol s uc u e simula ion, ec i ie building and i s
ac ua ing. Pa i ion o his pape was made in wo
ways – con ol s uc u e simula ion and con ol
s uc u e ac ua ing. Applied ec i ie ’s con ol
s uc u e is based upon he ma hema ical model
de i ed om ec o diag am (Fig.
1
) and is
desc ibed in he pa ag aph 2. The main goal o his
pape is o show and desc ibe p ac ical p oblems
which appea ed du ing con ol s uc u e ac ua ing.
Topic o CSAR is no e y common and he
published pape s mos ly deal wi h he h ee phase
e sion. Publica ions a e a he heo e ical,
esea ches go in o he p oblems connec ed wi h
con ol in pa icula using hys e esis con ol o
PWM modula ion (e.g. [1] - [3]). Un o una ely, we
did no ind any complex pape dealing wi h single
phase e sion o ac ion applica ions.
2. RECTIFIER’S CONTROL POSSIBILITIES
AND SIMULATIONS
Func ion o ec i ie ’s con ol is o main ain g id
( olley) cu en cu e (i) in ha monic shape and in
phase wi h powe g id ol age (u). We can gene ally
use wo con ol me hods: hys e esis cu en con ol
me hod ( o he cu en consumed om he powe
g id), o he me hod using PWM modula ion wi h
cons an swi ching equency. The second me hod
(PWM) is used in he design o CSAR model
dedica ed o labo a o y measu emen . This me hod
has been chosen ega ding possible in e ac ion wi h
ailway signaling, because dis u bance p oduced by
cons an swi ching equency is much easie o
elimina e han in case o hys e esis con ol.
Mo eo e , he PWM con ol makes possible o
employ shi ed ca ie s, which is eligible o high
powe sys ems wi h low swi ching equency. In
consequence o conside ed low swi ching equency,
he synch onous PWM has been implemen ed.
The powe ci cui con igu a ion and ec o
diag am o designed CSAR is shown in Fig. 1. The
p oposed con e e con ol is displayed in Fig. 2.
This s uc u e includes cu en con ol loop which
independen ly on phase shi be ween powe g id
ol age (U) and g id cu en (I
(1)
) ensu es demanded
load cu en (I
d
). The ou pu o load cu en
con olle is demanded g id cu en ampli ude (I
m
*).
Cos ϕ = 1 (ze o phase shi be ween U and I
(1)
) is
being eached by con ol o bo h angle  and he
ampli ude o I
V(1).
Con ol o angle  is based upon
he ma hema ical model de i ed om ec o
diag am (see Fig. 1) and is e alua ed om known
pa ame e s. I s alue also has o sa is y he alue o
equi ed I
d
.
Fig. 1. Powe ci cui con igu a ion (simula ion wi ing)
and ec o diag am o
ϕ
=0
U
I
I
U
ε
δ
θ
I
(1)
.X
σ
C(1)
V(1)
I
(1)
C
Single phase cu en -sou ce ac i e ec i ie o ac ion…
87
Fig. 2. Designed CSAR con ol ci cui
I he load cu en is su icien ly high, he designed
con ol wo ks p ope ly and ensu es bo h he equi ed
load cu en and he phase shi ϕ=0. Howe e , i
demanded load cu en is lowe han ce ain le el
(I
dmin
), he con ol is no able o ensu e he ze o phase
shi (ϕ=0) be ween powe g id ol age and g id
cu en . When ϕ=0, he lowes possible I
V(1)
cu en
alue is I
V(1)min
=I
C(1)
. The e o e, he minimum I
dmin
is
de e mined by I
(1)min
. In his case, he con e e
con ol s uc u e con ols only I
d
cu en alue by
means o du y cycle (z), while angle  is pe manen ly
se o ze o. This solu ion was de i ed om he
p inciple o con ol s uc u e and he ac ha wi h
 = 0, he load cu en ipple is minimal. This esul
has been con i med by simula ions. In his case angle
ϕ is no con olled and depends only on he load
pa ame e s.
The solu ion o he abo e desc ibed p oblem wi h
con ollabili y o  (and o cou se ϕ) is o choose he
lowes possible capaci ance o he inpu il e
capaci o (C). On he o he hand, he capaci ance
mus also sa is y he condi ion o accep able u
C
ol age ipple and mus espec he equi ed il e
esonan equency.
F om his is e iden big disad an age o his
model-based con ol s uc u e (Fig. 2), which
equi es knowledge o R, Lσ, C and ω (powe g id
equency). The con ol equi es measu emen o I
d
,
U, U
ou
. Du y cycle (z) is being de i ed om he load
cu en con olle ou pu (I
m*
) by means o low-pass
il e . Supply ol age (powe g id ol age)
measu emen is also impo an due o ime
synch oniza ion o con ol algo i hm wi h his
ol age and powe componen s swi ching logic.
Simula ions we e made in p og amming language
PASCAL wi h he main emphases on he con ol
p inciple e i ica ion. I was made wi h espec o
se ial diodes e e se pa ame e s, swi ching
componen s (IGBTs) we e conside ed ideal.
Examples o simula ion esul s a e shown on Fig. 3 -
Fig. 5.
I is clea ha i is necessa y o bewa e o he inpu
il e (L
σ
C) esonan equency. Swi ching (ca ie )
equency chosen nea his esonan equency causes
ib a ion o his ci cui . To each he minimal
dis o ion o g id cu en he smoo hing induc o (L)
should be app oxima ely 3 imes highe hen in
common ec i ie .
Fig. 3. Simula ion esul : Id* < Idmin (con olled only
du y cycle z,  = 0)
Fig. 4. Simula ion esul : Id* > Idmin , close o Idmin
Fig. 5. Simula ion esul : 4c Id* > Idmin
3. SYNCHRONIZATION PROBLEMS
In o de o keep p ope unc ion o CSAR, i is
necessa y o synch onize he con ol s uc u e wi h
powe g id ol age cu e. Modula ion cu e
equency mus be coinciden al wi h powe g id
equency wi h espec o ol age pola i y. This
in o ma ion can be ob ained by di e en ways
depending on how much in o ma ion we ha e o
know abou he ol age cu e. When supposing
( )
(
)








⋅⋅
−−⋅⋅⋅+⋅⋅
−=
*
V
*
2
*
V
2
*
2
*2
2
II2
IIICLCU
a ccos
U
IRU
II
dou
*
d
*
⋅+
⋅=
2
I
zI
*
d
*
⋅=
-500
-400
-300
-200
-100
0
100
200
300
400
500
4,00E-01 4,05E-01 4,10E-01 4,15E-01 4,20E-01 4,25E-01 4,30E-01 4,35E-01 4,40E-01
(10x) i
u
ud
(10x) id
-500
-400
-300
-200
-100
0
100
200
300
400
500
4,00E-01 4,05E-01 4,10E-01 4,15E-01 4,20E-01 4,25E-01 4,30E-01 4,35E-01 4,40E-01
(10x) id
(10x) i
u
ud
-500
-400
-300
-200
-100
0
100
200
300
400
500
4,00E-01 4,05E-01 4,10E-01 4,15E-01 4,20E-01 4,25E-01 4,30E-01 4,35E-01 4,40E-01
(10x) Id
ud
u
(10x) i
Ad ances in Elec ical and Elec onic Enginee ing
88
pu ely sinusoidal ol age cu e, we do no need o
obse e i s shape. In his case we only need o know
he momen s when he ol age cu e c osses he ze o
axes (momen s o pola i y change) and he ol age
pola i y in e e y hal -pe iod. The easies way o
ollow his condi ion (which is also used in ou
applica ion), is o con e sinusoidal cu e (powe
g id ol age) in o he squa e shape wi h logical le els
o 0 and 3V, o he wise log. 0 and log.1 as well. Log.
0 co esponds o nega i e hal -wa e, log. 1 o
posi i e. Signal edges indica e he ze o c ossings.
Fig. 6. Failu e s a e o pe iod measu ing
Fig. 7. G id cu en esonan glimme
Fig. 8. Faul y esponse o g id equency s ep change
Fig. 9. Ze o ec o inse ion – p ope esponse o g id
equency s ep change
Fig. 10. P ope esponse o g id equency s ep change:
inc eased equency
P ocesso e alua es hese ze o c ossings by means
o ex e nal in e up ; pola i y is e alua ed om he
ze o c ossing di ec ion - ising o alling edge.
This easy p inciple app o ed i sel du ing es ing
despi e a ew limi a ions. Sinusoidal / squa e
con e e is ealized ou side he DSP, whe e ol age
ansduce signal dis u bance appea ed due o powe
ansis o s swi ching. Con e e e alua ed hese
glimme s like a mul iple pola i y change, which also
caused he glimme s o squa e synch oniza ion
edges. F equency measu ing has been ealized by
ime measu ing be ween wo ollowing edges and
his ime was consequen ly used o ollowing hal -
pe iod. Because o glimme s in synch oniza ion,
p ocesso e alua ed he ime be ween wo ollowing
glimme s like a hal -pe iod ime ollowed by aul
s a e which caused high swi ching equency du ing
he ollowing hal -pe iod o abou 20 kHz (
Fig. 6
) –
he swi ching equency inc eased due o employed
synch onous PWM.
The solu ion o his p oblem was so wa e
implemen a ion o glimme s insensibili y. I s
p inciple is o accep only he i s coming edge and
igno ing he es du ing he p ese ime ha is o
cou se sho e han he ime o longe hal -pe iod o
be expec ed. Ano he alid edge is he ollowing ze o
c ossing.
i
d
i
u
u
c
i
i
d
u
ou
i
d
synch oniza ion
u
c
i
synch oniza ion
i
i
d
synch oniza ion
i
i
d
Single phase cu en -sou ce ac i e ec i ie o ac ion…
89
Fig. 11. Final CSAR p o o ype: Id, I, U a UC in s eady
s a e
Fig. 12. De ail o wa e o ms om Fig. 11
Ano he complica ion o his synch oniza ion
me hod is he du y cycle accu acy. As al eady
men ioned, DSP measu ed he i s ol age hal -
pe iod ime which was hen used o se ing o
ollowing hal -pe iod modula ion cu e. This way
has an ad an age in as e esponse on equency
change, bu has also g ea e demand on du y cycle
accu acy. I he i s hal -pe iod is sho e han he
ollowing one, in he second hal -pe iod he
modula ion cu e comes in o ze o ea lie hen
ol age cu e and a gap in he g id cu en appea . I
he si ua ion is opposi e, which means he i s hal -
pe iod is longe hen he ollowing one, he o e lay
o modula ing cu e o e he eal one happen. When
he pola i y o g id cu en du ing swi ching-o e is
no in ze o ye , esonan glimme o g id cu en
appea ed and equency o glimme s is gi en by
inpu LC il e . This si ua ion is shown in Fig. 7. The
solu ion was o al e na e be ween measu ing o he
i s hal -pe iod and he ollowing one and se he
modula ion cu e pe iod acco ding o hese
al e na ing alues. This way elimina ed g id cu en
glimme s du ing ze o c ossing.
Ano he p oblem appea ed du ing powe g id
ol age equency s ep change (Fig. 8). A e aul y
eac ion o hal -pe iod leng h change ea ly swi ch-
o e o swi ching ansis o s o posi i e and nega i e
powe g id ol age hal -pe iod. Consequen ly, he
CSAR ca ied on like a diode ec i ie which means
ha g id cu en inc eased apidly and was gi en
only by load pa ame e s. As a p ecau ion o his aul
we gained ze o ec o inse ing ( ealized as a load
sho ci cui ). I he modula ion cu e c osses ze o
axes ea lie hen powe g id ol age, ze o ec o
con inues un il he nex edge indica ing nex ol age
ze o c ossing occu (Fig. 9). This p ecau ion has one
mo e unc ion, because when ou age o powe g id
happen (e.g. olley bounce), load cu en I
d
dec eases con inuously o ze o. Opposi e si ua ion
happen when equency inc eases (Fig. 10).
Modula ion cu e can no inish he cycle and
swi ch-o e happen wi h nonze o cu en i. In his
case he con ol s uc u e is able o a oid he
o e cu en shown in Fig. 8.
Fig. 11 and Fig. 12 con i m he p ope beha iou
o he inal p o o ype employing all abo e desc ibed
imp o emen s o bo h con ol sys em and powe
ci cui .
4. CONCLUSION
The designed labo a o y p o o ype (7kVA) o
ac ion CSAR employs model-based con ol sys em
wi h synch onous PWM. This me hod has been
chosen ega ding possible in e ac ion wi h ailway
signaling, because dis u bance p oduced by cons an
swi ching equency (especially in case o
synch onous modula ion) is much easie o p edic
and, he e o e, elimina e han in case o hys e esis
con ol. Mo eo e , he PWM con ol makes possible
o employ shi ed ca ie s, which is eligible o high
powe sys ems wi h low swi ching equency. The
simula ion and expe imen al esul s con i m p ope
unc ion o designed con ol s uc u e unde bo h
s eady s a e and ansien condi ions. The
expe imen s also e i ied he co ec con e e
beha iou du ing he aul s. The bigges disad an age
o p oposed model-based con ol is necessi y o inpu
il e pa ame e s knowledge and he educed
obus ness agains pa ame e a ia ions. The ac ual
esea ch is ocused on he imp o emen o con e e
beha iou unde dis o ed powe g id ol age.
REFERENCES
[1] Wang, X.; Joos, G.: Ope a ing limi s o he
cu en - egula ed del a-modula ed cu en -
sou ce PWM ec i ie , Indus ial Elec onics,
IEEE T ansac ions on,Volume: 38, Issue: 4, 199
1,page 268 – 274
[2] Wang, X.; Ooi, B.: Uni y PF cu en -sou ce
ec i ie based on dynamic ilogic PWM, Powe
Elec onics, IEEE T ansac ions on, Volume:8,
Issue: 3 , 1993, pages 288–294
[3] Damec, V.: Se ial esonan in e e s o using
in AC elec ic mo o s, Ph.D. hesis, Os a a,
2003, 98 pages (in czech)
[4] Vond ášek, F.: Cu en -sou ce ac i e ec i ie s:
Na ional con e ence o elec ical machines
XXVII, 2001, 364 pages (in Czech)
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