VOLUME XX, 2017 1
Da e o publica ion xxxx 00, 0000, da e o cu en e sion xxxx 00, 0000.
Digi al Objec Iden i ie 10.1109/ACCESS.2024.Doi Numbe
A No el Uni ied Single-Phase Ac i e Rec i ie
Topology wi h Ad anced Ope a ing Modes o
Sma G ids
Vi o Mon ei o1, (Senio Membe , IEEE), Filipe Cos a1, Se gio Coelho1, (S uden Membe ,
IEEE) and Joao L. A onso1, (Senio Membe , IEEE)
1 Cen o ALGORITMI / LASI, Uni e si y o Minho, Po ugal
Co esponding au ho : Vi o Mon ei o (e-mail: mon ei [email protected] )
This pa ag aph o he i s oo no e will con ain suppo in o ma ion, including sponso and inancial suppo acknowledgmen . Fo example,
“This wo k was suppo ed in pa by he U.S. Depa men o Comme ce unde G an BS123456.”
ABSTRACT Ac i e ec i ie s a e o pa amoun impo ance o gua an eeing powe quali y in sma g ids,
due o hei cha ac e is ics o sinusoidal cu en consump ion and uni a y powe ac o ope a ion. In his
pape , a no el uni ied single-phase (USP) on -end con e e is p oposed o ac i e ec i ie applica ions in
sma g ids, o e ing addi ional ad an ages and a se o ele an ea u es besides he con en ional ac i e
ec i ica ion. Wi h he p oposed USP on -end con e e , he ollowing independen ope a ion modes a e
a ailable: (i) ope a ion as a adi ional ac i e ec i ie , ensu ing sinusoidal AC g id cu en (wi h e y low
o al ha monic dis o ion), uni a y powe ac o , and con olled DC link ol age; (ii) ope a ion as a shun
ac i e powe il e , p oducing a cu en wi h con olled ha monic con en and phase angle a he undamen al
equency, in o de o ensu e almos sinusoidal cu en and a uni a y powe ac o a he AC powe g id; (iii)
combined ope a ion as an ac i e ec i ie and as a shun ac i e powe il e , p o iding powe o he DC load,
while simul aneously p oducing a cu en wa e o m wi h educed ha monic con en and con olled powe
ac o . By con olling hese indi idual ope a ion modes, elec ical appliances in sma g ids can ope a e
dynamically and collabo a i ely, imp o ing powe quali y. In addi ion, he p oposed USP on end con e e
may ope a e as a single-phase diode ec i ie in case o con ol sys em ailu e o damage o he con olled
swi ching de ices. This si ua ion is pa icula ly ele an since i allows o supply he DC load e en unde
such un o una e ci cums ances. Along wi h he pape , he opology o he p oposed USP on end con e e ,
i s p inciple o ope a ion, and he con ol s a egies o each ope a ion mode, a e sepa a ely explained. A 3.6
kW, 230 V – 50 Hz labo a o ial p o o ype o he p oposed USP on end con e e is p esen ed, and he
expe imen al alida ion is ca ied ou o all ope a ion modes.
INDEX TERMS Ac i e Rec i ie , Ac i e Powe Fil e , Powe Quali y, Single-Phase, Sma G id
I. INTRODUCTION
The pionee ing model o sma g ids is indispu ably
in luenced by he exis ence o new ound echnologies, e.g.,
elec ic mobili y and enewables, aiming o add ess
en i onmen al and sus ainable ma e s, bu a he same ime,
hey also in oduce an unp edic able beha io [1], [2], and
pose signi ican challenges, such as cybe secu i y isks [3]. In
addi ion, as an impe a i e ea u e gi en hei powe p o ile,
such echnologies mus no nega i ely impac he powe
quali y [4], [5], e en when ope a ing in a mul i unc ional
coope a ion [6], o wi h on-boa d/o -boa d EV cha ge s [7],
[8]. Thus, a cus oma y con ibu ion o diminish he poo powe
quali y ega ding eac i e powe and cu en ha monics,
consis s in he subs i u ion o he old passi e AC-DC ec i ie s
by ac i e ec i ie s [9], [10]. As he name implies, ac i e
ec i ie s o e con ollabili y ega ding he AC cu en ,
d i ing he ope a ion wi h sinusoidal cu en and uni a y
powe ac o . This is easible o each by employing dis inc
opologies o powe con e e s, whe e he mos widesp ead
and simple o con ol is he boos con igu a ion [11], [12],
howe e new opologies a e iden i ied [13], [14]. Al hough
classi ied as a on -end con e e , i is ca ego ized by he
in e nal cons i u ion o wo powe s ages: a passi e AC-DC
ec i ie and a con olled DC-DC con e e . Consequen ly, all
8 VOLUME XX, 2017
he powe deli e ed o he DC load is p ocessed by hese wo
powe s ages. Oppo unely, o he opologies can be used,
namely he b idgeless opologies, which a e ca ego ized by he
absence o he AC-DC passi e ec i ie [15], [16]. Despi e he
indubi able bene i s o he ac i e ec i ie s, hey a e solely
used o ensu ing sinusoidal cu en and uni a y powe ac o
on he AC side and con olled DC-link ol age on he DC side.
Howe e , by conside ing he eal con ex o sma g ids, i can
be aluable o add addi ional ea u es o he ac i e ec i ie s,
wi hou jeopa dizing i s main p inciple o ope a ion, bu
p o iding bene i s o he sma g id.
Thus, aligned wi h his hema ic, his pape p oposes a no el
uni ied single-phase (USP) on -end con e e designed o
ope a e in mul iple modes: (i) as a adi ional ac i e ec i ie ;
(ii) as a shun ac i e powe il e ; and (iii) in combined
ope a ion, as an ac i e ec i ie and as a shun ac i e powe
il e . The con ex and he opology o he p oposed USP
on -end con e e is shown in FIGURE 1, which is
composed by wo main pa s, namely a diode ull-b idge
con e e ( o med by he diodes d1 o d4), named as ull-wa e
ec i ie (FWR), and by a ull-con olled ull-b idge con e e
( o med by he IGBTs g1 o g4), named as bidi ec ional ac i e
ec i ie (BAR). The BAR has an in e media y DC-link (C1),
while he FWR con ains a DC-link in e ace (C2) o a DC-DC
back-end con e e o o a di ec connec ion wi h a DC load.
A common-mode induc i e il e is used o couple he USP
on -end con e e wi h he AC powe g id.
The possibili y o combining di e en ea u es and
echnologies, ei he h ough se e al powe con e e s o by
in eg a ing hem in o a single-s age solu ion, has al eady been
iden i ied and alida ed in he li e a u e. Fo ins ance, a
single-phase in e ace be ween dis ibu ed gene a ion and a
shun ac i e powe il e is p esen ed in [17]. Al hough i elies
on wo dis inc powe con e e s, i s main con ibu ion is he
implemen a ion o a neu al con ol s a egy. A combined
h ee-phase se ies-shun ac i e powe il e wi h a powe
con e e connec ed in he DC-link o in e ace a sola
pho o ol aic sys em is p esen ed in [18], pe mi ing he
ope a ion wi h ac i e/ eac i e powe con ol h ough he shun
il e . None heless, he solu ion equi es h ee dis inc powe
con e e s and does no p o ide a DC in e ace. A simila
s uc u e is p oposed in [19], bu wi hou a powe con e e o
in e ace he sola pho o ol aic sys em. This educes ha dwa e
complexi y bu limi s he sys em’s ope a ional lexibili y. In
con as , a hyb id DC in e ace combining ba e y s o age and
sola pho o ol aic sys ems is p esen ed in [20], enabling
ac i e/ eac i e powe con ol h ough he shun con e e .
Howe e , his app oach equi es addi ional con e e s and
lacks edundancy. An analogous design is p oposed in [21] o
h ee-phase applica ions, bu i s main d awback lies in he
impossibili y o con olling he ou pu DC-link ol age. In
addi ion, simila s uc u es can be implemen ed aiming o he
imp o emen o powe quali y, while also o e ing he
possibili y o ope a ing wi h bidi ec ional ac i e powe .
The e o e, bo h single-phase and h ee-phase sys ems a e
iden i ied, a ge ing he compensa ion o a enua ion o cu en
ha monics, he combined mi iga ion o ol age and cu en ,
and in some cases, eac i e powe compensa ion. No mally,
hese solu ions employ ull-b idge opologies, cascade
a angemen s, o o he inno a i e powe con e e s uc u es,
as p esen ed in [22]-[29]. Thus, i is ecognized he possibili y
o combining ea u es o ac i e ec i ie s wi h ac i e powe
il e s, which is o u mos impo ance. A comp ehensi e
compa ison is p esen ed in TABLE I, co e ing he p e iously
discussed app oaches. I includes he di e en ypes o
applica ion conside ed, he opology o powe elec onics
con e e s used, hei in eg a ion con ex , and he
co esponding compensa ion capabili ies. Suppo ed by he
analysis o he iden i ied bene i s and d awbacks, he
dis inguished ea u es o he p oposed USP on -end
con e e a e desc ibed as ollows:
1. Ope a ion in h ee dis inc modes, allowing o espond o
he powe needs o he DC side, as well as o p o ide
add- alue unc ions o he sma g id, namely: (a) ope a ion as
a adi ional ac i e ec i ie , ecei ing powe om he g id and
ensu ing sinusoidal AC cu en and uni a y powe ac o ;
(b) ope a ion as a shun ac i e powe il e , jus p oducing
eac i e powe and cu en ha monics o he powe g id o
ensu ing sinusoidal cu en and uni a y powe ac o in he
common coupling poin ; (c) combined ope a ion o bo h
p e ious cases, p o iding powe o he DC side, while
ope a ing as a shun ac i e powe il e , compensa ing cu en
FIGURE 1. P oposed uni ied single-phase (USP) on -end con e e .
L
g
a
g1
g2
b
g3
g4
C1
dc1
d1
d2
d3
d4
C2
dc2
iBAR
iFWR
igild
iUSP
idc
AC/DC Uni ied Single-Phase (USP)
AC
DC
DC
DC
iUSP
Loads
Powe
G id
8 VOLUME XX, 2017
ha monics and eac i e powe o he non-linea loads in he
same ins alla ion. 2. E en in he case o a ailu e o he BAR,
i is possible o p o ide powe o he DC side h ough he
FWR, which is an in e media e and p e e able comp omise
solu ion han no eeding he DC side, as happens in a
adi ional con e e . 3. Con olled cu en on he AC powe
g id, bu wi h in e nal cu en sepa a ion, i.e., he AC cu en
(iUSP) om he AC powe g id is di ided in o wo pa cels, he
FWR cu en (iFWR) and he BAR cu en (iBAR), allowing o
educe swi ching losses. 4. Con olled DC-link ol age in all
ope a ion modes, like a adi ional ac i e ec i ie on -end
con e e and whe e i can be connec ed a DC-DC back-end
con e e o a DC load. 5. Expe imen al alida ion o all he
p e ious cases, bo h in s eady-s a e and ansien -s a e, wi h a
ull de eloped labo a o y p o o ype, speci ically designed o
such pu pose, and es ed di ec ly plugged-in in o he 230 V
AC powe g id wi hou any con olled powe sou ce.
The cha ac e iza ion o he p oposed USP on -end
con e e amed wi h i s ad anced ope a ion modes in sma
g ids is in oduced in sec ion II. An explana ion o he
p oposed con ol algo i hm o he dis inc ope a ions is
p esen ed in sec ion III. The expe imen al se up and espec i e
alida ion o he e e ed ope a ion modes a e exposed in
sec ion IV. Finally, conclusions a e gi en in sec ion V.
II. PROPOSED UNIFIED FRONT-END CONVERTER:
PRINCIPLE OF OPERATION
A de ailed desc ip ion o he p oposed USP on -end
con e e is p esen ed in his sec ion, highligh ing he
di e en and independen ope a ion modes. FIGURE 2
isually explains he ope a ion o he USP on -end
con e e ac oss he h ee di e en ope a ing modes.
FIGURE 2(a) illus a es he ope a ion as a adi ional ac i e
ec i ie , ensu ing sinusoidal AC g id cu en (wi h e y
low o al ha monic dis o ion), uni a y powe ac o , and
con olled DC link ol age. FIGURE 2(b) illus a es he
ope a ion as a shun ac i e powe il e , p oducing a cu en
wi h con olled ha monic con en and phase angle a he
undamen al equency, o ensu e almos sinusoidal cu en
and a uni a y powe ac o a he AC powe g id. Finally,
FIGURE 2(c) illus a es he combined ope a ion as an
ac i e ec i ie and as a shun ac i e powe il e , p o iding
powe o he DC load, while simul aneously p oducing a
TABLE I. Comp ehensi e compa ison, including he di e en ypes o applica ion, he opology o
powe elec onics con e e s used and espec i e con ex ualiza ion o in eg a ion, as well as he compensa ion ope a ion.
Applica ion
Topology
Compensa ion
[17]
Dis ibu ed gene a ion in e acing
enewables h ough he dc-link
Single-phase ull-b idge in a
shun powe il e
Cu en ha monics
and eac i e powe
[18]
In e acing sola PV in he DC-link
wi hou addi ional con e e s
Th ee-phase ull-b idge in a
uni ied powe quali y condi ione
Cu en ha monics
and eac i e powe
[19]
In e acing sola PV in he DC-link
wi h addi ional DC-DC con e e
Th ee-phase ull-b idge in a
uni ied powe quali y condi ione
Cu en ha monics
and eac i e powe
[20]
In e acing ba e y s o age and sola PV
in he DC-link wi hou addi ional con e e s
Th ee-phase ull-b idge in a
uni ied powe quali y condi ione
Cu en ha monics
and eac i e powe
[21]
EV ba e y cha ge s, including an
addi ional DC-DC powe con e e
Th ee-phase swiss ec i ie in a
shun powe il e
Cu en ha monics
and eac i e powe
[22]
In e acing ba e y s o age and sola PV
in he DC-link wi h addi ional con e e s
Th ee-phase ull-b idge in a
uni ied powe quali y condi ione
Cu en ha monics
and eac i e powe
[23]
In e acing ba e y s o age and sola PV
in he DC-link wi h addi ional con e e s
Th ee-phase ull-b idge in a
uni e sal ac i e powe il e
Cu en ha monics
and eac i e powe
[24]
In e acing sola PV in he DC-link
wi h addi ional DC-DC con e e
Th ee-phase ull-b idge in a
uni e sal ac i e powe il e
Cu en ha monics
and eac i e powe
[25]
In e acing sola PV in he DC-link
wi hou addi ional DC-DC con e e
Th ee-phase ull-b idge in a
shun powe il e
Pa ial cu en ha monic
compensa ion
[26]
In e acing sola PV in he DC-link
wi hou addi ional DC-DC con e e
Single-phase ull b idge in a
se ies/shun powe il e
Cu en ha monics
and eac i e powe
[27]
In e acing EV wi h addi ional
DC-DC con e e
Single-phase o em-pole boos
powe ac o co ec ion
Cu en ha monics
educ ion
[28]
In e acing EV and sola PV
in he DC-link wi h addi ional con e e s
Th ee-phase ull-b idge in a
shun powe il e
Reac i e powe
compensa ion
[29]
In e acing EV, ba e y s o age and sola PV
in he DC-link wi h addi ional con e e s
Th ee-phase Cascade ull-b idge in a
shun ac i e powe il e
Cu en ha monics
and eac i e powe
8 VOLUME XX, 2017
cu en wa e o m wi h educed ha monic con en and
con olled powe ac o .
FIGURE 2. Ope a ion o he USP on -end con e e ac oss he h ee
di e en ope a ing modes: (a) Ope a ion as a adi ional ac i e ec i ie ;
(b) Ope a ion as a shun ac i e powe il e ; (c) Combined ope a ion as
an ac i e ec i ie and as a shun ac i e powe il e .
A. Ope a ion Mode: Ac i e Rec i ie
The main pu pose o an ac i e ec i ie is ela ed o he
AC side, o cing he ope a ion wi h sinusoidal cu en and
uni a y powe ac o . In his mode, he powe is p o ided
by he AC powe g id o he DC side h ough he USP
on -end con e e , which also con ols he DC-link
ol age, so ha he back-end con e e can p ope ly con ol
he ol age and cu en le els o he DC load. In his
ope a ion mode, he USP on -end con e e ope a es wi h
sinusoidal cu en and uni a y powe ac o , howe e , since
non-linea loads a e connec ed in he same elec ical
ins alla ion, he main cu en in he powe g id, which is he
sum o he cu en s, p esen ha monic con en , and he
powe g id exchanges eac i e powe . This si ua ion is
illus a ed in FIGURE 3.
Any opology o ac i e ec i ie needs o es ablish a
p ope synch oniza ion wi h AC ol age o con ol he
desi ed cu en . Consequen ly, a phase-locked loop (PLL)
algo i hm is used o ex ac he undamen al componen o
he AC ol age [30]. This algo i hm is no only used o
achie e synch oniza ion bu also o accomplish he
gene a ion o a sinusoidal AC e e ence cu en in he
p esence o a non-sinusoidal AC ol age. In ac , his
co esponds o he ac ual si ua ion o he AC ol age
nowadays, which p esen s ha monic dis o ion. By using
he undamen al componen o he AC ol age ins ead o i s
o al alue, i.e., no including he ha monic con en , i is
possible o achie e a sinusoidal AC cu en , he eby he
USP on -end con e e only ope a es jus wi h ac i e
powe . O he wise, he ha monic con en o he AC cu en
would be he same as he ha monic con en o he AC
ol age, which would cause he con e e o ope a e wi h
ha monic powe .
FIGURE 3. Ope a ion mode o he USP on -end con e e as ac i e
ec i ie , whe e i ope a es wi h sinusoidal cu en and uni a y powe
ac o (iUSP), bu due o he non-linea loads in he same elec ical
ins alla ion (ild), he cu en in he powe g id (ig) has ha monic con en .
8 VOLUME XX, 2017
To con ol he AC cu en , a e e ence cu en gene a ion
algo i hm based on he F yze Buchholz Depenb ock (FBD)
heo y was used [31], [32], which is a sui able con ol
heo y o single-phase g id connec ed powe con e e s. In
his heo y, he con e e is modeled by a conduc ance,
consuming a sinusoidal cu en in phase wi h he AC
ol age. The ampli ude o he AC e e ence cu en depends
upon he ope a ing powe , which con ains wo main
componen s: he powe needed o he DC load (pdc) (which
can be a di ec DC load o h ough a DC-DC back-end), and
he powe equi ed o egula e bo h DC-link ol age (p eg),
whe e a p opo ional-in eg al (PI) con olle is used. To
a oid an oscilla ion wi h wice he AC ol age equency,
which is in insic o single-phase g id- ollowing powe
con e e s, he a e age alues o ol age and cu en we e
used o he calcula ion o he equi ed powe . The alue o
pdc is ob ained by he p oduc o he a e age alues o he
DC-link ol age ( dc2) wi h he inpu cu en o he DC
load (idc) (o DC-DC back-end con e e ). The e o e, he
AC e e ence cu en (iUSP*) is ob ained acco ding o:
𝑖𝑈𝑆𝑃∗(𝑡)= −2 𝑣𝑝𝑙𝑙(𝑡) 𝑝𝑟𝑒𝑔(𝑡)+ 𝑝𝑑𝑐(𝑡)
𝑉𝑝𝑘𝑝𝑙𝑙(𝑡) ,
(1)
whe e pll and Vpkpll co espond, espec i ely, o he
undamen al componen and o he peak alue o he AC
ol age. As p e iously men ioned, he USP on -end
con e e has as ele an ea u e he in e nal di ision o
cu en s. Thus, FIGURE 4 depic s he inne cu en
sepa a ion o he p oposed USP on -end con e e when
ope a ing jus as an ac i e ec i ie . As expec ed, iUSP is
sinusoidal, co esponding o he sum o iBAR wi h iFWR (i.e.,
iFWR(d1) when iUSP is posi i e and iFWR(d2) when iUSP is
nega i e). As he connec ion o bo h in e nal pa s is
pe o med downs eam o he AC coupling induc o , hese
inne cu en s a e swi ched a high equency, i.e., he
cu en o he FWR is pulsed wi h he esul ing swi ching
equency o he BAR. This app oach allows o
subs an ially educe he RMS alue o he FWR inpu
cu en , which con ibu es o educe he powe losses.
Mo eo e , in his ope a ion mode he DC-link o he BAR
( dc1) supplies powe o he DC-link o he FWR ( dc2),
egula ing simul aneously he a e age alue o bo h
ol ages. Since he FWR is a unidi ec ional opology, he
espec i e DC-link can only p o ide powe o he DC load
o DC-DC back-end con e e .
Howe e , he a angemen o he BAR and he FWR
ca ies a sub le issue o he in eg i y o he USP on -end
con e e when powe is being ans e ed be ween bo h
DC-links. The ope a ion o he BAR connec s in pa allel C1
and C2, bu he exis ing dead- ime be ween he IGBTs o
he same leg causes he disconnec ion o he wo DC-links.
As he DC-links a e no longe connec ed in pa allel, hei
ol ages will no be balanced. The e o e, when he IGBT
swi ching es ablishes a new connec ion be ween C1 and C2,
high cu en spikes can low in he con e e due o he
pa allel connec ion o non-equal ol age capaci i e
elemen s, which may cause damage o he powe
semiconduc o s. This phenomenon occu s in a mo e in ense
way when using unipola pulse-wid h modula ion (PWM)
due o he ze o-le el o he p oduced ol age. To alle ia e
his p oblem, a low alue induc o can be connec ed o
in e ace bo h BAR and FWR, educing he cu en s ess
and allowing a p ope ope a ion o he BAR also wi h
unipola PWM swi ching scheme.
FIGURE 4. Cu en o he p oposed USP on -end con e e (iUSP) and
he in e nal cu en s in he BAR (iBAR) and in he FWR (iFWR).
B. Ope a ion Mode: Shun Ac i e Powe Fil e
In he p e ious sec ion, he adi ional ope a ion using he
p oposed USP on -end con e e as an ac i e ec i ie was
in oduced. Besides ha , as p esen ed be o e, one o he
main ad an ages o he p oposed USP on -end con e e
is he possibili y o ope a e as a shun ac i e powe il e .
This new ope a ion mode consis s in con olling he USP
on -end con e e o compensa ing cu en ha monics
and eac i e powe on he powe g id side. Consequen ly,
in his ope a ion mode, he exchange o ac i e powe
be ween he AC powe g id and he DC load is no equi ed,
ep esen ing an essen ial asse o suppo ing powe
quali y. The USP on -end con e e ope a es wi h
non-sinusoidal cu en o compensa e he cu en
ha monics o he non-linea loads connec ed in he same
elec ical ins alla ion, and consequen ly, he main cu en
in he powe g id is sinusoidal and he powe g id only
p o ides ac i e powe . This si ua ion is illus a ed in
FIGURE 5.
0 A
40 A
-40 A
0 A
40 A
-40 A
0 A
40 A
-40 A
0.00 s 0.01 s 0.02 s 0.03 s 0.04 s 0.05 s
20 A
21 A
19 A
0 A
40 A
-40 A
0 A
40 A
-40 A
0.02506 s 0.02496 s
iUSP
iBAR
iFWR (d1) iFWR (d2)
8 VOLUME XX, 2017
FIGURE 5. Ope a ion mode o he USP on -end con e e as shun
ac i e powe il e , whe e i ope a es wi h non-sinusoidal cu en (iUSP),
and due o i s ope a ion, compensa ing he cu en ha monic con en o
he non-linea loads (ild), he cu en in he powe g id (ig) becomes
sinusoidal.
The AC e e ence cu en o he USP on -end con e e
ope a ing as a shun ac i e powe il e is also ob ained wi h
he FBD powe heo y, which is a la gely applied con ol
heo y in ac i e powe il e s. Howe e , in his ope a ion
mode, he USP on -end con e e canno be modeled by a
conduc ance, since i mus supply he eac i e powe and
ha monic cu en s demanded by he AC loads connec ed o
he powe g id. Ins ead, he AC loads a e modeled by a
conduc ance (meaning he undamen al ac i e powe
abso bed) connec ed in pa allel wi h a ha monic cu en
sou ce (meaning he undamen al eac i e powe and he
ha monic cu en s abso bed by he AC loads). Hence, when
ope a ing as a shun ac i e powe il e , he USP on -end
con e e mus ope a e as a ha monic cu en sou ce, so he
AC powe g id is only able o p o ide undamen al ac i e
powe (i.e., he ha monic cu en and eac i e powe is
exchanged jus be ween he USP on -end con e e and
he AC loads). In his con ex , he equi alen conduc ance
is also calcula ed, bu since he USP on -end con e e
does no ope a e as an ac i e ec i ie , he powe componen
pdc is no used. In i s place, i is used he ac i e powe
consumed by he AC loads (pld), which is calcula ed by a
hal -cycle a e age o he ins an aneous load powe . I is
used only a hal -cycle o he AC ol age because i is
assumed ha he AC loads only abso b odd ha monic
cu en s, which makes he ins an aneous load powe o ha e
wice he powe g id equency. Besides, he u iliza ion o
he hal -cycle a e age ins ead o he ull-cycle e sion,
p o ides a as e ansien esponse owa ds AC load
changing. To gene a e he AC e e ence cu en when
ope a ing as a shun ac i e powe il e , he equi alen
conduc ance cu en should be sub ac ed om he loads
cu en (ild), which esul s in he ha monic cu en s and
eac i e powe abso bed by he loads and p o ided by he
USP on -end con e e , acco ding o:
𝑖𝑈𝑆𝑃∗(𝑡)= 𝑖𝑙𝑑(𝑡)− 2𝑝𝑟𝑒𝑔(𝑡) 𝑣𝑝𝑙𝑙(𝑡)
𝑉𝑝𝑘𝑝𝑙𝑙(𝑡) .
(2)
Once again, he undamen al componen o he AC
ol age is used so, due o he ope a ion o he USP on -end
con e e as a shun ac i e powe il e , he g id cu en can
be sinusoidal wi h uni a y powe ac o . Con a ily o he
ope a ion jus as an ac i e ec i ie , when he USP on -end
con e e ope a es jus as a shun ac i e powe il e , he
FWR is no used, since i s DC-link ol age emains
cons an wi h a sligh ly highe alue han he DC-link o
he BAR, p o iding no cu en low in he FWR diodes.
Hence, he p oposed USP on -end con e e beha es as a
egula AC-DC con e e .
C. Ope a ion Mode: Combina ion o Ac i e Rec i ie
and Shun Ac i e Powe Fil e
The combined ope a ion as an ac i e ec i ie and as a
shun ac i e powe il e is a ele an ope a ion mode o
enhancing powe quali y in sma g ids. The ope a ion
mode p esen ed in his sec ion combines he ac i e ec i ie
p ocess wi h he shun ac i e powe il e ea u es, i.e., he
p oposed USP on -end con e e ope a es wi h a double
pu pose. In his ope a ion mode, he USP on -end
con e e ope a es wi h non-sinusoidal cu en o
compensa e he cu en ha monics o he non-linea loads
connec ed in he same elec ical ins alla ion. In addi ion o
he ha monic con en , i also p esen s cu en in he
undamen al equency o he powe g id (50 Hz), ensu ing
ha i ope a es also wi h ac i e powe . Consequen ly, he
main cu en in he powe g id becomes sinusoidal and he
powe g id only p o ides ac i e powe , o he loads and
o he USP on -end con e e . This si ua ion is illus a ed
in FIGURE 6.
To achie e he combined unc ionali ies, he FBD heo y
should be modi ied o encompass bo h powe componen s
pdc and pld. Like he shun ac i e powe il e ope a ion
mode, he USP on -end con e e abso bs cu en wi h he
ha monic con en and eac i e powe equi ed by he AC
loads connec ed o he AC powe g id. The only di e ence
lies in i s highe ampli ude in he combined ope a ion
modes, due o he addi ional powe componen equi ed,
p o ided by he USP on -end o he DC loads. Thus, he
AC e e ence cu en calcula ion is e y simila o he shun
ac i e powe il e case, which is gi en by:
𝑖𝑈𝑆𝑃∗(𝑡) = 𝑖𝑙𝑑(𝑡) − 2𝑣𝑝𝑙𝑙(𝑡)𝑝𝑟𝑒𝑔(𝑡)+ 𝑝𝑑𝑐(𝑡)+ 𝑝𝑙𝑑(𝑡)
𝑉𝑝𝑘𝑝𝑙𝑙(𝑡)
(3)
8 VOLUME XX, 2017
FIGURE 6. Ope a ion mode o he USP on -end con e e as a
combina ion o ac i e ec i ie and shun ac i e powe il e , whe e i
ope a es wi h non-sinusoidal cu en (iUSP), composed by he
undamen al equency o he powe g id cu en (50 Hz) ( esponsible
o ensu ing he ope a ion wi h ac i e powe ) and by he cu en
ha monics ( esponsible o compensa ing he cu en ha monic con en
o he non-linea loads (ild)), esul ing in a sinusoidal cu en in he
powe g id (ig).
III. PROPOSED DIGITAL CURRENT CONTROL
ALGORITHM
The p oposed con ol algo i hm, encompassing he
dis inc ope a ion modes o he p oposed USP on -end
con e e , is p esen ed in his sec ion. A lowcha o he
con ol algo i hm is shown in FIGURE 7. As can be seen,
he i s s ep consis s in eading he di e en analog o
digi al con e e (ADC) channels. A e ha , he
synch oniza ion wi h he AC ol age is pe o med by
means o he PLL algo i hm and he DC-link ol age is
con olled o he es ablished e e ence a e age alue.
Acco ding o he ope a ion mode selec ion (ac i e ec i ie ;
shun ac i e powe il e ; o combined ac i e ec i ie and
shun ac i e powe il e ), he AC e e ence cu en is
es ablished, and he cu en con ol is pe o med h ough a
PWM scheme wi h a ca ie equency o 20 kHz. The
ending p ocess is ollowed by he s a s age o accomplish
he selec ed sampling equency o 40 kHz.
The PLL algo i hm and he DC-link ol age egula ion
a e p ocessed independen ly o he selec ed ope a ion mode
o he USP on -end con e e , since hey ep esen i al
elemen s o he con ol sys em o any AC-DC con e e
connec ed o he AC powe g id. The essen ial di e ence
be ween he ope a ion modes consis s in he calcula ed
powe componen s used in he equi alen conduc ance
cu en calcula ion o he FBD powe heo y. He ea e , he
cu en con ol is p ocessed, so ha iUSP acks he a ained
AC e e ence p ope ly. Fo his pu pose, i was
implemen ed a p edic i e-based cu en con ol ha
calcula es he e e ence ol age ab* (be ween poin s a and
b iden i ied in FIGURE 1) ha is compa ed wi h he PWM
ca ie o ob ain he ga e-pulse o he IGBTs and,
consequen ly, o p oducing he cu en iUSP acco ding o i s
e e ence. Fo each gi en sampling ime ins an k, he
e e ence ol age ab* is gi en by:
𝑣𝑎𝑏∗[𝑘]= 𝑣𝑔[𝑘]+𝐿
𝑇𝑠(2𝑖𝑔∗[𝑘]− 𝑖𝑔∗[𝑘 − 1]+ 𝑖𝑔[𝑘]) ,
(4)
whe e g deno es he ins an aneous alue o he AC ol age,
L he induc ance alue o he g id connec ed coupled
induc o and Ts he sampling pe iod.
FIGURE 7. Flowcha o he de eloped con ol algo i hm o he
p oposed USP on -end con e e .
IV. EXPERIMENTAL SETUP AND VALIDATION
The iabili y o he p oposed USP on -end con e e
was e i ied wi h a labo a o ial p o o ype, especially
de eloped o such pu pose. A digi al signal p ocesso
(DSP), wi h he model TMS320F28335, manu ac u ed by
Texas Ins umen s, was used o digi al con ol
implemen a ion. In he concei ed powe con e e , IGBTs
wi h he model FGA25N120N, swi ched a 20 kHz, and
diodes wi h he model DUR6060W, we e used. The
DC-link (C2) is composed by a se o capaci o s pe o ming
a o al capaci ance o 1.12 mF (450 V), and he
in e media y DC-link (C1) is composed by a se o
capaci o s pe o ming a o al capaci ance o 2.8 mF
(450 V). Since he opology o he USP on -end con e e
allows a bidi ec ional powe low h ough he BAR and a
unidi ec ional low h ough he FWR, a g ea e capaci y
was ob ained in he in e media y DC-link (C1). Thus, o
he ope a ion mode as an ac i e ec i ie and o he
combined ope a ion as an ac i e ec i ie and as a shun
S a
Read ADC
PLL Synch oniza ion
P eg Calcula ion
Ac i e
Rec i ie ?
YY
P edic i e Con ol
PWM (20 kHz)
End
NN
Pld Calcula ionPDC Calcula ion
Re e ence
Calcula ion
Ac i e
Powe Fil e ?
Y
N
Ac i e
Rec i ie and Powe
Fil e ?
PDC, Pld Calcula ion
8 VOLUME XX, 2017
ac i e powe il e , he USP on -end con e e has a o al
DC-link capaci y esul ing om he sum o C1 and C2,
while in he ope a ion mode jus as a shun ac i e powe
il e , solely he capaci y o C1 is conside ed. The USP
on -end con e e is connec ed o he AC powe g id by
means o a coupled induc o wi h a o al alue o 2.2 mH.
The powe con e e o he USP on -end con e e has a
physical size o 17 cm x 17 cm. The digi al con ol sys em
is inco po a ed in o a 1U ack uni , which includes he DSP,
he signal condi ioning boa d wi h ex e nal ADC, he
ex e nal DAC, he con ol boa ds o he d i e s, and he
powe supply module (+15 V, GND, -15 V). The p o o ype
was de eloped o labo a o y alida ion and, he e o e, i
can be u he op imized om an indus ial pe spec i e.
The labo a o ial se up is shown in FIGURE 8. The
expe imen al esul s we e ob ained wi h a digi al
oscilloscope (Yokogawa model DL708E) and wi h a powe
quali y analyze (Fluke, model 435) o he h ee dis inc
ope a ion modes: (i) ac i e ec i ie ; (ii) shun ac i e powe
il e ; (iii) and ac i e ec i ie combined wi h he shun
ac i e powe il e ope a ion.
Al hough he p oposed USP on -end con e e was
speci ically designed o alida ion unde 230 V – 50 Hz
condi ions, and o a maximum powe o 3.6 kW, i has he
po en ial o be adap ed o o he ol age and powe a ings.
This would equi e a e ision o eplacemen o he main
componen s o mee he speci ic applica ion equi emen s,
which includes he mig a ion o a h ee-phase e sion. In
such case, i can o e o he con ol ad an ages o he main
powe g id, such as he possibili y o ope a ing wi h
di e en alues o cu en ha monics and powe ac o
among he h ee phases. Rega dless o whe he a
single-phase o h ee-phase e sion is used, se e al USP
on -end con e e s can be combined wi hin he same
ins alla ion, enabling a modula and scalable solu ion. This
app oach can be ele an since i allows he es ablishmen
o a dynamic p oduc ion o selec ed cu en ha monics and
eac i e powe . The e o e, acco ding o he a ailabili y o
he indi idual USP on -end con e e s, each one o hem
can p oduce selec ed cu en ha monics and a speci ic alue
o eac i e powe , wi h he main goal o ensu ing sinusoidal
cu en in he powe g id and uni a y powe ac o (e.g., one
USP on -end con e e can p oduce 3 d o de cu en
ha monics and o he one can p oduce jus eac i e powe ).
This ep esen s an appealing con ibu ion o powe quali y
managemen in sma g ids.
In he pe spec i e o indus ializing he USP on -end
con e e , i is impo an he conside a ion o o he
componen s and ma e ials ensu ing high e iciency ac oss
a ying powe le els (e.g., by conside ing wide band gap
semiconduc o s and amo phous/nanoc ys alline co es o
he L coupling il e s). Among o he conside a ions, his
analysis mus be pe o med conside ing he equi emen s
o he inal applica ion, he ol age ange, and he
adap abili y o di e se ope a ing condi ions (e.g., o
he mal managemen ), in o de o s ablish a ade-o
be ween a ious powe le els and e iciency.
FIGURE 8. Labo a o ial se up used o ob ain expe imen al esul s.
A. Ope a ion Mode: Ac i e Rec i ie
FIGURE 9 shows he expe imen al esul s o he
p oposed USP on -end con e e , ob ained o he
ope a ion as an ac i e ec i ie o an ac i e powe o 1 kW.
Fo he AC side, he AC g id ol age ( g) and iUSP a e
isible, and o he DC side, his igu e shows bo h DC-link
ol ages ( dc1 and dc2) and he DC cu en (idc) (in he
expe imen al alida ion a esis i e load was conside ed).
As powe quali y is an impo an aspec o he AC powe
g id, du ing his ope a ion mode, he p oposed USP
on -end con e e ope a es wi h uni a y powe ac o and
a low o al ha monic dis o ion (THD% = 3.8%) in he
con olled iUSP. The THD and he spec al analysis o his
cu en a e shown in FIGURE 10. FIGURE 11 shows an
expe imen al esul du ing a ansien -s a e, highligh ing
he momen when he USP on -end begins i s ope a ion as
ac i e ec i ie . In he i s s age, i ope a es as a passi e
ec i ie (i.e., diode b idge) and in he second s age as an
ac i e ec i ie , whe e i is demons a ed ha he cu en
becomes sinusoidal in he second s age. In addi ion, due o
he ope a ion as ac i e ec i ie , he DC-link ol age VDC2
also inc eases.
The p oposed con ol s a egy o he USP on -end
con e e gua an ies ha he AC g id cu en is sinusoidal
independen ly o he ha monic dis o ion o he AC g id
ol age, exhibi ing a ele an cha ac e is ic o he p oposed
USP on -end con e e . As a o emen ioned, he cu en
sepa a ion be ween he FWR and he BAR is one o he
main ad an ages o he p oposed USP on -end con e e .
FIGURE 12 shows he expe imen al measu e o he iBAR
and he iUSP, whe e he BAR cu en ms alue is
subs an ially educed compa ed o he AC g id cu en .
8 VOLUME XX, 2017
FIGURE 9. Expe imen al esul s o he USP on -end con e e du ing
he ope a ion as ac i e ec i ie : G id ol age ( g); USP on -end
con e e cu en (iUSP); DC-link ol ages ( dc1 and dc2); DC cu en (idc).
FIGURE 10. Expe imen al esul s o he USP on -end con e e du ing
he ope a ion as ac i e ec i ie : THD and spec al analysis o he
cu en (iUSP).
FIGURE 11. Expe imen al esul s o he USP on -end con e e du ing
he ansien -s a e om he ope a ion as passi e ec i ie o he
ope a ion as ac i e ec i ie : G id ol age ( g); G id cu en (ig); DC-link
ol ages ( dc1 and dc2).
B. Ope a ion Mode: Shun Ac i e Powe Fil e
To alida e he p oposed USP on -end con e e o he
ope a ion as a shun ac i e powe il e , FIGURE 13 shows
he cu en consumed by a non-linea load connec ed o he
AC powe g id. The THD and he spec al analysis o he
ild a e shown in FIGURE 14.
FIGURE 12. Expe imen al esul s o he USP on -end con e e du ing
he ope a ion as ac i e ec i ie : De ail o he BAR cu en (iBAR) and USP
on -end con e e cu en (iUSP).
FIGURE 13. Expe imen al esul s o he USP on -end con e e du ing
he ope a ion as shun ac i e powe il e : G id ol age ( g); cu en
consumed by a non-linea load connec ed o he powe g id (ild); DC-link
ol age dc1.
FIGURE 14. Expe imen al esul s o he USP on -end con e e du ing
he ope a ion as shun ac i e powe il e : THD and spec al analysis o
he cu en consumed by a non-linea load connec ed o he powe g id
(ild).
g
iUSP
idc dc1 dc2
g
iUSP
iBAR
dc1 dc2
g
ild
dc1
