Internati
o
nal
Journal of Ele
c
trical
and Computer
Engineering
(IJE
CE)
V
o
l.
5, N
o
. 2
,
A
p
r
il
201
5, p
p
.
23
1
~
24
2
I
S
SN
: 208
8-8
7
0
8
2
31
Jo
urn
a
l
h
o
me
pa
ge
: h
ttp
://iaesjo
u
r
na
l.com/
o
n
lin
e/ind
e
x.ph
p
/
IJECE
DC UPS for Criti
c
al
Load
s
Gane
sh S,
Chi
r
anjit Ghosh
T, Kokilasree
R, Nandhakumar M,
Md Haroon Alim T
Dept. of
EEE, S
a
veetha School
of Engin
eerin
g,
Saveeth
a
Univ
er
sity
, Ch
e
nnai, Tamilnadu,
India
Article Info
A
B
STRAC
T
Article histo
r
y:
Received Dec 10, 2010
Rev
i
sed
Jan 23, 201
5
Accepte
d
Fe
b 5, 2015
The usual way
to avoid a computer s
hutdown during a mains f
a
ilur
e
is to
connect an
uninterruptible po
wer
supply
s
y
s
t
em (UPS), which can b
e
suitably
modified and fitted inside
the comp
uter cabinet b
y
the use of
proposed methodolog
y
known as a dc
UPS. Conventional desk top UPS
s
y
s
t
em
s
s
t
ore el
ectr
i
ci
t
y
in form
of chem
ic
al en
erg
y
in ba
tte
ries
and when
ever m
a
ins
fai
l
t
h
e batt
eri
e
s
provide DC power which is
then
con
v
erter
to ac
b
y
inverter and
then fed to the computer
in order to save critical data. Thus
power from mains or from UPS is fed
to switch
e
d mode power supply
unit
which conver
t
s it to dc to suppl
y the com
puter m
o
therboard
and a
ccessories
.
Leav
ing th
e case of the computer
power
ed b
y
mains, during power
failur
e
the
dc power is un
necessarily
conv
erted
to
a
c
and
then to d
c
ag
ai
n in S
M
P
S
hence high switching losses and heat is produced there b
y
making the entir
e
s
y
stem ver
y
low
efficient. In this work
it is proposed to directly
feed th
e dc
power from
the
bat
t
er
y
to
the
com
put
er SMPS s
y
stem b
y
building a UPS
arrangem
e
nt
wit
h
in the
com
pute
r
s
y
s
t
em
.
This
not onl
y s
a
v
e
s
s
p
ace,
it
is
highly
efficien
t compared to the convention
a
l up
s sy
stem, eas
y
to carr
y
, lo
w
cos
t
and
re
liab
l
e s
i
nc
e
there
is
no
ch
ange over operation
is r
e
quired
.
A
complete design
of an
ac to d
c
power
supply
with an
intern
al dc UPS is
presented in
this
paper. A prototy
p
e h
a
s been fully
d
e
velop
e
d an
d tested as
a
PC power supply
.
Keyword:
Co
m
p
u
t
er
power
su
pp
ly
SMPS
Swi
t
c
he
d m
o
d
e
p
o
we
r s
u
ppl
i
e
s
Un
i
n
terrup
tib
l
e
po
wer system
UPS
Copyright ©
201
5 Institut
e
o
f
Ad
vanced
Engin
eer
ing and S
c
i
e
nce.
All rights re
se
rve
d
.
Co
rresp
ond
i
ng
Autho
r
:
Gane
sh
S,
Dept. of E
EE,
Saveet
ha
Sc
ho
ol
o
f
E
n
gi
nee
r
i
n
g
,
Sa
veet
ha
U
n
i
v
e
r
si
t
y
, C
h
e
n
nai
,
Tam
i
l
n
adu
,
I
n
di
a
1.
INTRODUCTION
There a
r
e m
a
ny indust
r
ial applications in
which if
m
a
ins falls can cause
critical dam
a
ge, not
only to
t
h
e pr
ocess i
n
vol
ved
,
b
u
t
al
so t
o
the equipment. A comm
on case is in
fo
rm
ati
on l
o
ss
caused
by
t
h
e sud
d
e
n
sh
u
t
do
wn
in
PCs. Cu
rren
tly, n
e
w co
m
p
an
y ed
ifices usu
a
ll
y h
a
v
e
an
un
interrup
tib
le
p
o
wer system
(UPS) t
h
at
feeds t
h
e equipm
ent of the whole bu
ilding. However, i
n
m
a
ny other cas
es, each i
ndi
vidual use
r
has to
connect a personal UPS to the com
puter in order
t
o
a
voi
d an
une
x
p
ect
ed s
hut
do
wn
. The
r
e are
m
a
ny
co
mmercial p
r
o
d
u
c
ts of th
is typ
e
b
u
t
g
e
nerally, all
are
ac UPSs—t
hei
r
output volta
ge is an ac voltage
(sinu
s
o
i
d
a
l, squ
a
re, trap
ezo
i
dal, etc.) th
at su
b
s
titu
tes
th
e
main
s vo
ltag
e
. Ho
wev
e
r, th
e pro
b
l
em
can
b
e
so
lved
i
n
ot
he
r way
s
,
i
.
e., by
su
p
p
l
y
i
ng t
h
e dc
out
p
u
t
v
o
l
t
a
ge o
f
t
h
e po
wer s
u
ppl
y
di
rect
l
y
from
the bat
t
e
ry
(
d
c
UPS
)
.
Thi
s
ap
pr
oac
h
i
s
al
so vi
abl
e
,
especi
al
l
y
i
f
t
h
ere i
s
o
n
l
y
one
dc o
u
t
p
ut
. M
o
reo
v
er
, i
f
t
h
e
n
o
m
i
nal
i
nput
v
o
l
t
a
ge
is sim
i
lar to the battery volta
ge, the
s
o
lution can
be very
sim
p
le because
the sam
e
converter can
be
us
ed and
onl
y
som
e
ki
n
d
o
f
swi
t
c
h s
h
oul
d be i
m
pl
em
ent
e
d i
n
o
r
de
r t
o
fee
d
t
h
e c
o
n
v
e
r
t
e
r f
r
om
t
h
e m
a
i
n
s or f
r
o
m
t
h
e
bat
t
e
ry
. O
n
t
h
e ot
her
han
d
,
a po
wer c
o
n
v
e
r
si
o
n
sh
o
u
l
d
b
e
do
ne i
f
t
h
e
bat
t
e
ry
vol
t
a
ge
i
s
di
ffere
nt
fr
om
t
h
e
nom
i
n
al
i
nput
vol
t
a
ge
, an
d t
h
e com
m
on way
i
s
t
o
use a
not
h
e
r dc
–
d
c co
n
v
e
r
t
e
r t
o
t
r
a
n
s
f
o
r
m
t
h
e bat
t
e
ry
v
o
l
t
a
ge
i
n
t
o
one si
m
i
lar t
o
t
h
e
n
o
m
i
nal
i
n
put
vol
t
a
ge.
Of c
o
urse
,
t
h
e ot
her
o
p
t
i
on i
s
t
o
obt
ai
n t
h
e
o
u
t
p
ut
v
o
l
t
a
ge
d
i
rectly fro
m
t
h
is au
x
iliary co
nv
erter.
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISS
N
:
2088-8708
DC UPS fo
r Critica
l
Loa
d
s
(
G
a
n
es
h S)
23
2
Fi
gu
re
1.
B
l
oc
k
di
ag
ram
of t
h
e co
nve
nt
i
o
nal
and
p
r
op
ose
d
s
y
st
em
Howev
e
r, if th
e p
o
wer supp
ly h
a
s
m
u
ltip
le
o
u
t
pu
ts (as in a PC p
o
w
er su
pp
ly) and
all
o
f
th
em
are
com
p
letely regulated, t
h
e s
o
lution is
not s
o
sim
p
le becaus
e
the
out
put
vo
ltages ca
nnot
be
directly obtained
from
the batte
ry unless t
h
e
whole power
stage is re
p
licated
, th
at is—to
h
a
v
e
two
co
m
p
letely
d
i
fferen
t
con
v
e
r
t
e
rs—
o
ne
o
p
erat
i
n
g
f
r
om
t
h
e m
a
i
n
s an
d a
n
ot
he
r
one
ope
rat
i
n
g
fr
om
t
h
ebat
t
e
r
y
, an
d
b
o
t
h
o
f
t
h
em
o
b
t
ain
i
n
g
all th
e ou
tpu
t
v
o
l
t
a
g
e
s. App
a
ren
t
ly, th
e size
an
d
co
st of th
e syste
m
will als
o
b
e
dup
licated
.Th
i
s
p
a
p
e
r
d
eals with
th
e d
e
sign o
f
a power
su
pp
ly with
a
n
internal
dc
UPS t
h
at m
e
e
t
s all the Advanced
Tech
nol
ogy
ex
t
e
nde
d (
A
T
X
)
speci
fi
cat
i
o
ns i
n
o
r
de
r t
o
be
used as a PC power s
u
pply
. There are six
different
out
put
v
o
l
t
a
ge
s f
r
om
t
h
e
AT
X, a
n
d al
l
of
t
h
em
sho
u
l
d
be
t
i
ght
l
y
re
g
u
l
a
t
e
d as
s
h
o
w
n T
a
bl
e
1.
It
s
h
ou
l
d
be
note
d
that the
size specifications
are als
o
the sam
e
, so th
at th
is m
o
d
e
l cou
l
d
fit in
to
th
e
stan
d
a
rd ch
assis o
f
a
PC po
w
e
r
supp
ly. Th
e
g
o
a
l i
s
no
t to
i
n
cr
ease th
e co
st in ord
e
r to
o
f
f
e
r a
new
featu
r
e (5–1
0 m
i
n
au
to
nomy)
a
t
a slightly hi
gher cost tha
n
the stan
d
a
r
d
PC
po
we
r
s
u
p
p
l
y
cost
.
T
h
i
s
feat
ure
c
o
ul
d be d
e
m
onst
r
at
ed
i
f
t
h
e
P
C
whe
r
e
placed in the
area
where expe
rie
n
ces
freque
nt m
a
ins failures
.
Table 1
.
Vo
ltag
e
To
leran
ces
Rail Voltage
Tolerance
+5 VDC
± 5 %
-5 VDC
± 5 %
+12 VDC
± 5 %
-
12 VDC
± 5 %
+3
.3
VDC
± 4
%
+5 VSB
± 5 %
Fi
gu
re 2.
DC
UPS
base
d o
n
a
hi
g
h
-
v
o
l
t
a
ge bat
t
e
ry
From
t
h
e i
n
d
u
s
t
r
i
a
l
poi
nt
of
vi
ew, i
t
c
oul
d
be i
n
t
e
rest
i
ng t
o
de
si
g
n
a m
odul
a
r
p
o
w
er s
u
ppl
y
w
h
i
c
h
coul
d be
used
fo
r ot
h
e
r t
y
pes
of ap
pl
i
cat
i
o
n
s
and
not
onl
y
fo
r a PC
, w
h
i
c
h i
s
a very
spe
c
i
f
i
c
use. M
a
n
y
ot
he
r
in
du
strial equ
i
p
m
en
t n
eed
mu
lti-ou
tpu
t
power sup
p
lies
bu
t th
e vo
ltag
e
v
a
lu
es can
b
e
v
e
ry
d
i
fferen
t
.
So
, t
h
e
m
a
nufact
ure
r
c
oul
d
use t
h
e sa
m
e
pr
od
uct
f
o
r
di
f
f
ere
n
t
c
u
st
o
m
ers i
f
t
h
e
o
u
t
put
v
o
l
t
a
ges a
n
d
po
we
r rat
i
n
g
s
can
h
a
v
e
so
m
e
adju
stm
e
n
t
cap
abilit
y.Th
e topo
lo
g
y
u
s
ed
in th
is p
a
p
e
r is
based
o
n
th
e i
d
ea
o
f
a m
u
lt
i-in
pu
t
co
nv
erter—o
n
e in
pu
t
b
e
ing
t
h
e ac m
a
in
s and
th
e o
t
h
e
r inpu
t b
e
i
n
g th
e b
a
ttery. In prev
iou
s
cases th
is co
n
c
ept
w
a
s
u
s
ed
w
ith th
e
f
l
yba
c
k
co
nv
er
te
r
an
d th
e
for
w
ar
d conve
rter a
n
d ea
ch indivi
dual i
n
put
had a s
p
ecific
cont
rol
ci
rc
ui
t
wi
t
h
a speci
fi
c
pul
se-
w
i
d
t
h
-m
od
ul
at
i
on
(P
W
M
) IC
. The t
o
pol
ogy
p
r
ese
n
t
e
d he
re i
s
base
d o
n
a
h
a
lf-bridg
e con
v
e
rter and
the b
a
ttery in
p
u
t is
in
teg
r
ated with the seconda
r
y
wi
ndi
n
g
. Th
us
, t
h
ere
i
s
no
ad
d
ition
a
l sp
ecific wind
ing
in
th
e tran
sfo
r
mer to
con
n
e
ct th
e b
a
ttery.
Lik
e
wise, t
h
ere is o
n
l
y on
e
co
n
t
rol
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 2, A
p
ri
l
20
15
:
23
1 – 2
4
2
2
33
circu
it fo
r
bo
th
inpu
ts and
on
ly on
e PWM
IC is u
s
ed
. A
si
m
p
le lo
g
i
c ci
rcu
it sen
d
s
th
e PW
M
pu
lses
to
on
e
in
pu
t
o
r
t
h
e
o
t
h
e
r,
d
e
p
e
nd
ing on
t
h
e
v
o
ltag
e
of th
e ac m
a
in
s. If th
e m
a
in
s fail, t
h
e l
o
g
i
c circu
it
will sen
d
th
e
PW
M
p
u
l
s
e
s
to
t
h
e b
a
t
t
e
r
y
in
p
u
t
in
s
t
e
a
d
o
f
th
e
a
c
in
p
u
t
.
Fi
gu
re
3.
Sy
nc
hr
o
n
o
u
s
b
u
ck
c
o
n
v
e
r
t
e
r
use
d
a
s
a
post
-re
gul
at
or
2.
TOPOLOGY SELECTION
Th
e
o
b
j
ectiv
e i
s
to
d
e
sign
a
20
0-W
pow
er
su
pp
ly
outputs t
h
at can
operat
e
either from
the ac m
a
ins
or
fr
om
a 12
-V
bat
t
e
ry
.
It
i
s
cl
ear t
h
at
,
fr
om
the
poi
nt
o
f
vi
ew
of t
h
e t
o
p
o
l
ogy
,
i
t
w
oul
d
b
e
easi
e
r t
o
m
a
ke t
h
e
p
o
wer sup
p
l
y o
p
e
rate fro
m
a
h
i
gh
vo
ltag
e
battery th
an
from a
lo
w v
o
ltage so
urce. In
actu
a
l fact, if th
e b
a
ttery
vol
t
a
ge
i
s
hi
g
h
en
ou
g
h
(ar
o
u
n
d
t
h
e
pea
k
va
l
u
e
of t
h
e ac
i
n
put
v
o
l
t
a
ge)
,
w
e
co
ul
d
us
e t
h
e
sam
e
con
v
ert
e
r
but
fed i
n
t
h
i
s
case
fr
om
a dc v
o
l
t
a
ge. T
h
e
o
n
l
y
new
el
em
ent
that
sh
o
u
l
d
be
adde
d
w
oul
d b
e
a co
nt
r
o
l
l
e
d
swi
t
c
h
to select the i
n
put
powe
r s
o
urce.
Howev
e
r, from th
e safety (an
d
t
h
e reliabilit
y) p
o
i
n
t
of v
i
ew, th
is
o
p
tio
n
is h
i
gh
ly in
adv
i
sab
l
e.
M
o
re
ove
r,
hi
g
h
v
o
l
t
a
ge
bat
t
e
ri
es are m
u
ch m
o
re expen
s
i
v
e than low voltage batteries.
There
f
ore, t
h
e
selected
v
o
ltag
e
is 12
V, m
a
in
ly
d
u
e
to
th
e ex
trem
el
y lo
w co
st o
f
t
h
is typ
e
o
f
b
a
tt
ery. On
th
e o
t
her h
a
n
d
, th
is vo
ltag
e
value com
p
licates the im
ple
m
entation of the UPS cons
idera
b
ly becaus
e
the power
s
u
pply should
ope
rate
fr
om
t
w
o very
di
ffe
re
nt
i
n
p
u
t
vol
t
a
ges:
t
h
e
m
a
i
n
s ac vol
t
a
ge (
1
90
–
2
6
5
V rm
s) an
d t
h
e 12
-
V
bat
t
e
ry
dc
voltage
. T
h
e option
of usi
ng
a very wi
de
input voltage ra
nge
converter has
not e
v
e
n
be
en consi
d
ere
d
because
of t
h
e pe
rf
o
r
m
a
nce of t
h
e
s
e con
v
e
r
t
e
rs.
A
not
her i
m
port
a
nt
issu
e in
th
is d
e
sig
n
is th
e
m
o
du
larity o
f
th
e syste
m
.
Alth
oug
h
t
h
e
o
b
j
ectiv
e is to
co
m
p
ly with
th
e ATX sp
ecifi
cations,
partic
ularly as far
as
size is conce
r
ned, it
wo
ul
d
be
v
e
ry
fasci
n
at
i
n
g i
f
we c
oul
d sel
e
c
t
t
h
e
val
u
e
o
f
t
h
e
out
put
v
o
l
t
a
ges i
n
or
der
t
o
use
t
h
e
sam
e
po
we
r
sup
p
l
y
f
o
r
di
f
f
e
rent
a
ppl
i
cat
i
ons
. S
o
fo
r t
h
i
s
reas
on
, t
h
e
ou
tpu
t
of th
e ac
to
d
c
con
v
erter is a 12
-V
o
u
t
pu
t th
at
can
dri
v
e t
h
e
t
o
t
a
l
rat
e
d
p
o
w
er (
2
00
W).
Th
e ot
he
r
o
u
t
p
ut
s are t
h
en
p
o
st
r
e
gul
at
ed
f
r
om
t
h
i
s
m
a
i
n
one
(
i
n o
u
r
case, the dc t
o
dc converter i
s
a half-bri
dge
c
onve
rte
r)
by means of
buck converte
rs. So, any com
b
ination
of
vol
t
a
ge
ca
n
be
obt
ai
ne
d
by
sel
ect
i
ng t
h
e a
p
p
r
op
ri
at
e p
o
st
re
gul
at
o
r
s.
Taki
n
g
i
n
t
o
c
o
nsi
d
e
r
at
i
on t
h
a
t
a PC
needs qui
t
e
l
o
w
vol
t
a
ges t
o
o
p
erat
e (5 an
d 3.
3
V), t
h
e
buc
k
con
v
e
r
t
e
r desi
gne
d f
o
r t
h
i
s
p
u
r
p
ose was a s
y
nch
r
o
n
ous
b
u
c
k co
n
v
ert
e
r i
n
or
der t
o
i
m
prove t
h
e effi
ci
e
n
cy
as
m
u
ch
as po
ssib
le. Th
oug
h
th
e use
o
f
a
syn
c
hr
ono
us
MO
SFET is
m
o
r
e
ex
p
e
n
s
i
v
e th
an th
e
use of
a
con
v
e
n
t
i
onal
S
c
hot
t
k
y
d
i
o
de, t
h
e cost
of t
h
e
heat
si
nk
ne
e
d
ed can
be re
duced by in
c
r
easi
ng t
h
e efficiency and
en
larg
es th
e auto
no
m
y
o
f
th
e
UPS.
M
o
re
ove
r, as
t
h
e i
n
p
u
t
vol
t
a
ge
o
f
t
h
e
buc
k c
o
nve
rt
er
i
s
n
o
t
t
o
o
hi
g
h
(
1
2
V), t
h
e c
o
st
o
f
t
h
e co
nt
r
o
l
an
d
dri
v
e ci
rcui
t
c
a
n be
f
u
rt
he
r r
e
duce
d
.
A s
p
e
c
i
a
l
effo
rt
m
a
d
e
t
o
desi
gn a si
m
p
l
e
,
cost
effect
i
v
e
,
and di
sc
ret
e
dri
v
e ci
rc
ui
t
avoi
di
ng t
h
e
use of ei
t
h
e
r
p
u
l
s
e t
r
ans
f
orm
e
rs or ex
pen
s
i
v
e
co
mmercial d
r
iv
ers. It
shou
ld
b
e
m
e
n
tio
n
e
d
t
h
at th
e
bu
ck
ou
tpu
t
vo
ltag
e
is tr
immab
l
e fr
o
m
ar
oun
d 9–3
V.
Two of t
h
ese
post
re
gulators
can
be i
n
corporate
d
int
o
th
e m
a
in
bo
ard
an
d, th
er
efor
e, t
h
e
p
o
w
e
r su
pply can
h
a
v
e
up
t
o
three d
i
fferen
t
p
o
wer rails—t
wo of th
em
with
a selectab
le ou
tput v
o
ltag
e
.
It
al
so
ha
ve t
w
o m
o
re o
u
t
p
ut
s (
−
12 V
a
n
d
−
5
V) a
r
e als
o
obtaine
d
from
the m
a
in converter.
In this
case, due to their low power
ratings
, the
−
1
2
V
out
put
i
s
o
b
t
a
i
n
ed
fr
om
the m
a
i
n
t
r
ansf
orm
e
r and r
e
g
u
l
at
ed by
mean
s o
f
cr
oss-
r
e
gu
latio
n
meth
od
s coup
ling
bo
th
ou
tpu
t
in
du
ctor
s in
t
h
e sam
e
co
r
e
. Th
e
−
5
V
out
put
i
s
obt
ai
ne
d f
r
o
m
t
h
e
−
12
V
out
put
by
m
eans of a l
i
n
ea
r re
g
u
l
a
t
o
r
c
o
nnect
ed in casca
de. Howe
ver, t
h
e
m
a
in
featu
r
e of t
h
is
p
o
wer su
pp
ly is th
at th
e UPS
sh
ou
l
d
fit
int
o
t
h
e
ATX chassis. As
has
been
mentioned, the
r
e are
sev
e
ral
op
tio
ns to
in
teg
r
ate t
h
e UPS in
t
o
th
e
p
o
wer so
ur
ce.Th
e
first
o
p
tion
is t
o
pu
t t
h
e
b
a
ttery on
t
h
e
p
r
im
ary
winding and to use a c
o
nverte
r to c
h
arge the
bul
k capacit
o
r
d
i
rectly fro
m
t
h
e b
a
ttery.
Thus, th
e m
a
in
d
c
to
dc
co
nv
erter will always h
a
v
e
a si
m
i
lar d
c
in
pu
t v
o
ltag
e
.
W
i
th
th
is o
p
tion
,
th
e v
o
ltag
e
d
i
fferen
ce b
e
tween
th
e
input and the output will be
quite large (10–14
V to 300–400
V), and
it will be necessary to design a specific
conve
r
ter (c
ontrol syste
m
, specific tran
s
f
o
r
m
e
r, etc.,) fo
r this p
u
r
p
o
s
e
.
It
is i
m
p
o
r
tan
t
to
no
te th
at th
is
conve
r
ter would only operat
e for a fe
w minutes in case
o
f
a m
a
in
s failu
re; th
erefore, its co
st sh
ould
b
e
min
i
mized
, alth
oug
h
t
h
is conv
erter
wo
u
l
d
hav
e
to
d
r
i
v
e the rated
p
o
wer
(2
00
W).
In
th
is case, th
e best o
p
tion
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
DC UPS fo
r Critica
l
Loa
d
s
(
G
a
n
es
h S)
23
4
would
probabl
y
be a flyback converter
bec
a
use of its
si
m
p
l
i
city, ev
en
th
o
ugh
th
e size of the trans
f
orm
e
r
wo
ul
d
be
l
a
r
g
e
.
Fi
gu
re
4.
(a
)
U
PS sy
st
em
wi
th
bat
t
e
ry
o
n
pri
m
ary
si
de (
b
)
DC
U
PS
wi
t
h
bat
t
e
ry
o
n
sec
o
nda
ry
si
de
Fig
u
re
5
.
AC/
D
Conv
erter
with
a
UPS plac
ed on
the seconda
ry
Ano
t
h
e
r ch
o
i
ce is to
pu
t th
e battery o
n
t
h
e seco
nd
ar
y wind
i
n
g.
At first si
gh
t, it seem
s easier to
o
b
t
ain
a closely regul
ated 12-V
out
put from
a sim
i
lar input voltage. Howe
ver, this
is not obvi
ous at all because the
b
a
tter
y
v
o
ltag
e
can
ch
ang
e
f
r
o
m
ar
o
u
n
d
10
.5
–13
.6
V
and
as a co
n
s
equ
e
nce, th
e co
nv
er
t
e
r
n
eed
ed
should
b
e
abl
e
t
o
st
ep
-u
p
an
d st
e
p
-
d
ow
n t
h
e
out
put
v
o
l
t
a
ge de
pe
ndi
n
g
on
t
h
e
i
n
put
vol
t
a
ge
. T
h
e
s
o
l
u
t
i
o
n m
a
y
be t
o
use
abuc
k
–
b
o
o
st
con
v
e
r
t
e
r.
A bet
t
e
r opt
i
on m
i
ght
be t
o
m
a
ke pro
p
er
use o
f
t
h
e
m
a
i
n
t
r
ansfo
r
m
e
r and t
r
y
t
o
dri
v
e
th
e p
o
wer from th
e b
a
ttery t
o
th
e 12
-V ou
t
p
u
t
b
y
m
ean
s o
f
an
aux
iliary win
d
i
n
g
.
W
e
sh
ou
l
d
rem
e
mb
er th
at
t
h
e
m
a
i
n
conve
rt
er i
s
a hal
f
br
i
dge;
t
h
ere
f
o
r
e,
i
f
t
h
e sam
e
t
r
ansf
orm
e
r i
s
used, t
h
e wi
n
d
i
n
g
sho
u
l
d
be dri
v
en i
n
a sim
ilar way (a flyback c
o
nverter could
not be connect
ed
to this windi
ng because t
h
e transform
e
r would be
separate
d). For suc
h
case, t
h
e best c
hoice
see
m
s to
be to place the a
uxiliary
windi
ng
on the sec
o
nda
r
y
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 2, A
p
ri
l
20
15
:
23
1 – 2
4
2
2
35
wi
n
d
i
n
g.
As t
h
e i
n
p
u
t
an
d
out
put
vol
t
a
ge val
u
es ar
e si
m
i
l
a
r, t
h
e
best
sol
u
t
i
on i
s
t
o
use
a
pus
h
–
p
u
l
l
co
n
v
ert
e
r
because both s
w
itches are c
o
nnecte
d
to
ground and the tra
n
sform
e
r is dri
v
en
symm
e
t
rically as
in the case of a
hal
f
-
b
ri
d
g
e co
nve
rt
er. M
o
re
ove
r, t
h
e p
u
s
h
–p
ul
l
wi
n
d
i
n
g
can be i
n
tegrated in the
ha
lf- bridge sec
o
nda
r
y
win
d
in
g.
Th
e m
a
in
co
nv
erter i
n
pu
t
v
o
ltag
e
rang
e is
1
90–
265
V
rms. Thu
s
, th
e inp
u
t
d
c
vo
ltag
e
rang
es
fro
m
26
5 •
√
2 =
37
5 V
d
ct
o
19
0 •
√
2
−
20%
= 220 Vdc (
−
20%
represents the
ripple acr
oss t
h
e bulk ca
pacitor).
If
t
h
e m
a
xim
u
m
dut
y
cy
cl
e i
s
s
e
t
aro
u
n
d
0
.
4
2
i
n
o
r
der
t
o
ha
v
e
som
e
m
a
rgi
n
f
o
r
dy
nam
i
c regul
at
i
o
n
p
u
r
p
oses a
t
lo
w lin
e co
nd
it
io
n
s
, th
e
m
a
in
tran
sform
e
r tu
rn
s ratio
shou
ld b
e
n
= 8
.
Th
us, th
e
m
a
x
i
m
u
m d
u
t
y cycle
i
s
0
.
43
,
the m
i
nim
u
m
duty cycle is
0.25, a
n
d the
nominal duty cy
cle is ar
oun
d 0.3
2
.
N
o
w
,
if
a
m
a
ins failure
o
ccurs
,
th
e p
u
sh–p
u
ll co
nv
erter will start o
p
e
ratin
g. If th
is con
v
e
rt
er is d
e
sign
ed
to
o
p
e
rate with th
e sa
m
e
d
u
t
y cycle
range as t
h
e half-bridge c
o
nverter, the t
r
ansition bet
w
een bot
h m
odes
of operati
on
will be ve
ry fast
because
the regulator
will not ha
ve
to accomm
odate its voltage
levels too much.In a hal
f
-bri
dge c
o
nve
r
ter, the
r
e
latio
n
s
h
i
p b
e
tw
een
t
h
e inputan
d
t
h
e
o
u
t
pu
t vo
ltag
e
is
Fi
gu
re
6.
(a
) T
r
ans
f
orm
e
r wi
n
d
i
n
gs a
n
d t
h
ei
r
n
u
m
b
er o
f
tu
r
n
s
fo
r t
h
e
basic sol
u
tion
,
(
b
)
H
a
lf-b
rid
g
e c
o
nv
erter
with
a
pu
sh
–pull co
up
led
on
t
h
e sam
e
tran
sfo
r
m
e
r, (c
) Rearrangem
ent of t
h
e
windings t
o
eliminate the
speci
fi
c
pu
sh
–
pul
l
wi
n
d
i
n
gs,
(d
)
Hal
f
-
b
ri
d
g
e
co
nve
rt
er
wi
t
h
a p
u
s
h
–p
ul
l
i
n
t
e
grat
ed
o
n
t
h
e
sam
e
seconda
r
y
win
d
in
gs
0
n1
(1
)
Wh
ere
Vin1
is th
e inpu
t voltag
e
of th
e con
v
e
rt
er and n1
isthe
tra
n
s
f
orme
r tu
rn
s
ratio b
e
tween th
e
hal
f
-
b
ri
d
g
e p
r
i
m
ary
wi
ndi
ng
and t
h
e sec
o
n
d
a
ry
wi
n
d
i
n
g.
I
n
a p
u
s
h
–p
ul
l
con
v
e
r
t
e
r, t
h
e
rel
a
t
i
ons
hi
p
be
t
w
een
t
h
e i
n
put
a
n
d t
h
e
out
put
v
o
l
t
a
ge i
s
0
2.
Vin2
n2
(2
)
W
h
er
e
V
i
n2
is
th
e inpu
t vo
ltag
e
o
f
th
e conver
t
er
and
n
2
is th
e t
r
an
sfo
r
mer
tur
n
s
r
a
tio
betw
een th
e
pu
sh
–pu
ll
pri
m
ary
wi
ndi
ng a
nd t
h
e sec
o
n
d
a
r
y
wi
ndi
n
g
.
If t
h
e sam
e
o
u
t
p
ut
vol
t
a
ge i
s
t
o
be obt
ai
ne
d wi
t
h
t
h
e sam
e
dut
y
cycle, the following e
x
pressi
on
ca
n be obt
ai
n
e
d fr
om
(1)
a
n
d (2
)
1
1
2.
2
2
(3
)
Let u
s
assu
m
e
th
at th
e av
erage vo
ltag
e
across th
e
bu
lk
cap
a
cito
r is
3
0
0
V i
n
n
o
m
in
al cond
itio
n
s
, th
e
b
a
ttery vo
ltag
e
is 12
V, and
th
e turns ratio of th
e
h
a
lf-b
ri
d
g
e
co
nve
rt
er i
s
n =
8.
Fr
om
(3
), t
h
e
nece
ssar
y
t
u
r
n
s
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
DC UPS fo
r Critica
l
Loa
d
s
(
G
a
n
es
h S)
23
6
ratio
for th
e
pu
sh–p
u
ll con
v
erter is
n
2
=
0
.
6
an
d th
e cl
o
s
est
feasib
le tu
rn
s
rati
o
is n
2
= 0
.
5
.
6
T
hu
s,
t
h
e
wi
n
d
i
n
g st
r
u
ct
ure
of t
h
e t
r
ansf
o
r
m
e
r wi
ll
be:
pri
m
ary wi
n
d
i
n
g 1
6
t
u
r
n
s, eac
h h
a
l
f-b
ri
d
g
e sec
o
n
d
a
r
y
wi
n
d
i
n
g—t
w
o
t
u
r
n
s, a
n
d
f
o
re
ach
pus
h
–
p
u
l
l
pri
m
ary
wi
ndi
ng
o
n
e t
u
rn
[F
i
g
u
r
e 6
(
a)]
.
O
bvi
ou
sl
y
,
d
u
e t
o
t
h
e
di
ffe
re
nce bet
w
een
b
o
t
h
i
n
p
u
t
v
o
l
t
a
ge ra
ng
es (3
7
5
/
2
20 =
1.
7 o
n
t
h
e m
a
ins an
d
13
.6/
1
0
= 1.3
6
on t
h
e bat
t
e
ry
)
,
it is n
o
t
po
ssib
l
e to
o
p
tim
ize t
h
is feat
u
r
e fo
r
th
e who
l
e range bu
t ju
st
for
no
m
i
n
a
l co
n
d
iti
o
n
s
.Fu
r
t
h
erm
o
re, t
h
e
sm
al
l
-
si
gnal
t
r
ansfe
r
fu
nct
i
o
n
o
f
bot
h c
o
n
v
e
r
t
e
rs i
s
very
si
m
i
l
a
r beca
use i
n
bot
h cases
, t
h
e
dy
nam
i
c beha
vi
o
u
r
is do
m
i
n
a
ted
by th
e ou
tpu
t
LC filter. Th
e tran
sfer
fun
c
tion of th
e h
a
lf-b
ri
d
g
e
conv
erter i
s
g
i
v
e
n as
1
ˆ
0
ˆ
1
1
1
(4
)
And t
h
e tra
n
s
f
er function of t
h
e
pu
sh
–
pul
l
c
o
n
v
e
r
t
e
r i
s
gi
v
e
n as
1
ˆ
0
ˆ
1
1
1
(5
)
Whe
r
e L is the induct
o
r of out
put filter,
C is
th
e capac
itor of
out
put filter, vˆ0 is a s
m
all signal
p
e
rt
u
r
b
a
tio
n of th
e ou
tpu
t
vo
l
t
ag
e, an
d
d
ˆ
is
a sm
a
ll sig
n
a
l p
e
rt
u
r
b
a
tio
n of th
e du
ty cycle.As t
h
e ou
tpu
t
filter
is th
e sam
e
an
d
th
e turn
s rat
i
o
s
o
f
bo
th
con
v
e
rters h
a
v
e
b
een d
e
sign
ed in
su
ch
a
way th
at th
e
ratio
(3) i
s
si
m
ilar, b
o
t
h
tran
sfer fun
c
tio
ns will b
e
practically id
en
tical. Th
us, th
e sam
e
v
o
ltag
e
reg
u
l
ato
r
can
b
e
u
s
ed
if
t
h
e co
n
v
ert
e
r
i
s
p
o
we
red
ei
t
h
er
by
t
h
e
hal
f
-
b
ri
dge
o
r
by
t
h
e
pu
sh
–
pul
l
.
H
o
weve
r,
t
h
i
s
st
ruct
ure
ca
n
be
rearrang
ed
in ord
e
r to in
tegrat
e th
e
p
u
sh–p
u
l
l
wi
nd
ing
s
in
to
th
e h
a
l
f
-b
ri
d
g
e
second
ary
wind
ing
s
.
As
we
kn
o
w
, t
h
e
vol
t
a
ge
wa
v
e
fo
rm
s on t
h
e
t
r
ans
-
fo
rm
er are similar in a half-bridge a
n
d
in a
pus
h–
pul
l
.
The
sec
o
nda
ry
wi
n
d
i
n
g
o
f
t
h
e
hal
f
-
b
r
i
dge t
r
ans
f
orm
e
r ca
n t
h
e
n
be
al
so
use
d
as
a p
u
s
h
–
p
u
l
l
p
r
im
ar
y
winding. T
h
us, as the battery
is placed in t
h
e seconda
ry
of the power s
upply and no isol
ation is nee
d
e
d
, the
trans
f
orm
e
r ca
n be use
d
as a
n
autot
r
ans
f
ormer and
sha
r
e
the sa
m
e
winding for the s
econda
r
y and
for the
pri
m
ary
of t
h
e
p
u
s
h
–
p
u
l
l
co
n
v
ert
e
r
.
I
n
st
ead
of
wi
ndi
ng
eac
h
half-bridge s
econda
r
y a
lto
geth
er (2
turn
s),
each
t
u
r
n
was w
o
un
d sepa
rat
e
l
y
i
n
orde
r t
o
ha
ve
t
h
e
m
i
ddl
e poi
nt
avai
l
a
bl
e o
n
a pi
n of t
h
e c
o
i
l
form
er (p
oi
nt
s D
an
d E), as show
n in
Figu
r
e
6(
c)
.
Thu
s
, in
ord
e
r to
i
m
p
l
e
m
en
t
t
h
e pu
sh–p
u
ll co
nv
erter, th
e battery o
n
l
y n
eed
s to
b
e
conn
ected
to
the
cent
r
e
poi
nt
o
f
t
h
e w
hol
e
hal
f
-b
ri
d
g
e sec
o
n
d
a
ry
wi
n
d
i
n
g (
p
oi
nt
B
)
a
nd
ea
ch M
O
S
F
ET t
o
t
h
e m
i
ddl
e p
o
i
n
t
o
f
each le
g
(point
s D and E). T
h
is way, each push–pull
prim
a
r
y ha
s
one
turn and t
h
e sec
ondary
has
two t
u
rns
as
i
n
t
h
e
p
r
e
v
i
o
us
arr
a
n
g
em
ent
(
t
he
di
o
d
es
of
t
h
e sec
o
nda
ry a
r
e c
o
nnected t
o
poi
nts
A a
nd B)
[Figure
6(c) a
nd
(d)].
As
we can
see,
o
n
e
turn
is
u
s
ed
bo
th fo
r th
e
pr
im
a
r
y and
t
h
e seco
nd
ar
y.W
h
en
t
h
e
p
o
w
e
r
supp
ly is
o
p
e
rating
no
rmall
y
u
s
in
g
the
m
a
in
s as th
e in
pu
t v
o
ltag
e
, S1
and
S2
are d
r
iv
en
as in a co
nv
en
tio
n
a
l h
a
lf-
bri
dge
co
n
v
ert
e
r.
O
n
t
h
e
ot
her
ha
n
d
,
b
o
t
h
S
3
an
d
S4
are
o
ff.
T
h
e
n
, t
h
e c
o
nve
rt
er i
s
o
p
erat
i
n
g as
a
co
nv
en
tio
n
a
l half
-
b
r
i
dg
e
co
nv
er
ter
[
F
i
g
ur
e 7
(
a)
].
Th
e
t
u
rn ratio
b
e
t
w
een
th
e prim
ary an
d
th
e secon
d
a
ry is n
1
= 16/2. T
hus
, t
h
e
voltage
acro
ss each one
-
turn
winding is
V
1
T =
(
V
C / (2
.2
.n
1)
)
(
6
)
Th
e
who
l
e h
a
l
f
-b
ri
d
g
e
second
ary will h
a
v
e
twice th
is
vo
ltag
e
acro
ss it an
d, h
e
n
ce,
(1
)
can
b
e
u
s
ed
j
u
st tak
i
ng
in
t
o
accoun
t th
at
th
e inp
u
t
v
o
l
tag
e
is th
e
v
o
ltag
e
across th
e bu
lk cap
acito
r VC.In
nomin
al
co
nd
itio
ns, t
h
e bo
d
y
d
i
od
es
S3
an
d S4
d
o
no
tcon
du
ct
b
ecau
s
e t
h
e
b
a
ttery vo
ltag
e
is
h
i
gh
er th
an
th
e vo
ltag
e
acro
s
s th
e on
e-tu
rn
wind
ing
an
d they a
r
e re
verse
biased
(
V
C /
(2
.2
.n
1)
) < V
B
A
T
T
(
7
)
Onl
y
w
h
en t
h
e
i
nput
v
o
l
t
a
ge i
s
hi
gh
er t
h
a
n
2
45
V an
d t
h
e b
a
t
t
e
ry
vol
t
a
ge i
s
near 1
0
V ca
n t
h
e b
o
d
y
d
i
od
es b
e
co
m
e
fo
rward
b
i
ased
.In
th
at
case,
th
e b
a
ttery
will b
e
in p
a
rallel with
t
h
e secon
d
a
ry
wind
ings and
a
high current can
flow through the battery and dam
a
ge it. To avoid
t
h
is, a
diode has been
placed in series with
th
e b
a
ttery
[Fi
g
ure
7
(
b
)
]. If
th
e m
a
in
s fail, S1
and
S2
ar
e tur
n
ed
O
FF and
S3
a
n
d
S4 a
r
e
dri
v
en as a
co
nv
en
tio
n
a
l
pu
sh–p
u
ll con
v
e
rter an
d th
e
energ
y
is
ob
tain
e
d
from
the battery.
As
we ca
n see, t
h
e tra
n
sform
e
r
is always d
r
i
v
en
symmetricall
y
an
d
th
e
secon
d
a
ry will al
ways h
a
v
e
a similar v
o
ltag
e
wav
e
fo
rm
[Figu
r
e 7
(
b
)
].
In t
h
is case, t
h
e voltage across each
one-t
u
rn winding will
be
the battery
voltage
(VBATT), a
n
d he
nce, the
v
o
ltag
e
acro
ss th
e who
l
e seco
nd
ary will b
e
twice th
is
v
a
lu
e.Thu
s
, th
e vo
ltag
e
at th
e in
pu
t of th
eLC
filter
(VLC
) is ve
ry sim
ilar in both cases (Figure 7(a
)
and
(b)) because, as
has bee
n
m
e
ntione
d, n1
and n2 ha
ve
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 2, A
p
ri
l
20
15
:
23
1 – 2
4
2
2
37
been
designe
d
i
n
suc
h
a way that the
du
ty cycles are m
o
re o
r
less th
e sam
e
.Mo
r
eov
e
r, in th
is o
p
e
ration
m
o
d
e
,
although the
prim
ary MOSFE
Ts are
off,
t
h
ere is som
e
power flow
from
th
e seconda
ry to
th
e pr
im
ar
y th
r
o
ugh
th
e bo
d
y
d
i
od
es o
f
S1
an
d
S2. As a co
n
s
equen
ce, th
e
bu
lk
cap
acito
r
will still b
e
ch
arg
e
d
.
Th
e vo
ltag
e
acro
ss
it will b
e
VC= V
BATT
x
16
x
2
(
8
)
Fig
u
r
e
7
.
(
a
)
Pro
p
o
s
ed
t
o
po
logy o
p
e
r
a
ting
as
a con
v
e
n
tion
a
l
h
a
lf
-br
i
dg
e co
nv
er
ter and
its
main
w
a
v
e
fo
rm
s
(b
) P
r
o
p
o
se
d t
o
p
o
l
o
gy
ope
rat
i
ng a
s
a
p
u
sh
–
pul
l
c
o
n
v
e
r
t
e
r
usi
n
g a
n
a
u
t
o
t
r
ansf
o
r
m
e
r
Fi
gu
re
8.
M
e
t
h
od
us
ed
t
o
dri
v
e t
h
e
gat
e
pul
s
e
s t
o
t
h
e
hal
f
-
b
ri
d
g
e
or t
o
t
h
e
pus
h
–
p
u
l
l
As th
e
b
a
ttery v
o
ltag
e
can
ch
ang
e
fro
m
1
0
to
13
.6
V, t
h
e v
o
ltag
e
across th
e bu
lk
cap
acito
r
will
chan
ge
fr
om
320
–
4
3
0
V
whe
n
t
h
e c
o
nv
ert
e
r i
s
o
p
e
r
at
i
n
g
i
n
t
h
e
UP
S m
ode.
A
very
i
m
port
a
nt
feat
u
r
e
of t
h
i
s
syste
m
is th
at t
h
e tran
sitio
n
between
the no
rmal o
p
e
ra
t
i
o
n
m
ode and t
h
e
UPS m
ode ca
n
be d
o
n
e real
l
y
fast
.A
s
men
tio
n
e
d earl
i
er, th
e
sm
al
l-sig
n
a
l tran
sfer
fu
n
c
tion
of bo
t
h
th
e m
a
in
h
a
lf-bridg
e co
nv
erter and
th
e pu
sh
–pu
ll
conve
r
ter are
quite sim
i
lar. Thus, the s
a
me PW
M cont
r
o
l
l
e
r and t
h
e sa
m
e
vol
t
a
ge re
gul
at
o
r
ci
rc
ui
t
can b
e
use
d
f
o
r
bot
h
con
v
e
r
t
e
rs t
o
d
r
i
v
e t
h
e
pul
ses
fr
om
one
co
n
v
ert
e
r
t
o
t
h
e
ot
her
(Fi
g
u
r
e
8
)
.
The
r
ef
o
r
e,
o
n
l
y
on
e
PW
M in
teg
r
at
ed
circu
it is u
s
ed
and
no
co
n
t
ro
l
o
r
protectio
n
circu
itry is du
p
licat
ed
. Th
e
on
ly ex
tra
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
DC UPS fo
r Critica
l
Loa
d
s
(
G
a
n
es
h S)
23
8
com
pone
nts are the MOSFE
Ts of the
pus
h–pull conve
r
ter no ad
ditional windings and
no a
dditional circuitry
are neede
d
.
Fi
gu
re
9.
Tra
n
s
i
t
i
on p
r
ocess
fr
om
t
h
e ope
rat
i
o
n
usi
n
g t
h
e
m
a
i
n
s t
o
t
h
e
o
p
er
at
i
on
usi
n
g t
h
e
bat
t
e
ry
Whe
n
a
m
a
i
n
s fai
l
u
re occ
u
rs
,
t
h
e i
nput
v
o
l
t
a
ge det
ect
o
r
ci
rcui
t
act
i
v
at
es a l
ogi
c ci
rcui
t
and
di
vert
s
th
e g
a
te pu
lses fro
m
th
e h
a
lf-b
ri
d
g
e
to
t
h
e
pu
sh–p
u
ll. Th
e t
r
an
sition
b
e
tween
b
o
t
h
m
o
d
e
s of
o
p
e
ration
can
b
e
done in one
high
fre
quency switching
cycle.As a c
ons
eque
nce, t
h
e capaci
tor
placed at the 12-V output
shoul
d
n
o
t
b
e
ov
erd
i
men
s
io
n
e
d
b
e
cau
s
e
it
can
n
o
lo
ng
er
stor
e any ad
d
ition
a
l energ
y
for t
h
e tran
sitio
n ti
m
e
. Th
ere
will n
o
t
b
e
an
y switch
i
ng
cycl
e with
n
o
en
erg
y
flow
fro
m
t
h
e inpu
t to
th
e
o
u
t
p
u
t
. In
fact, th
e ri
p
p
l
e
du
ri
n
g
th
e
tran
sitio
n
tim
e
will b
e
th
e same as in
a co
nv
en
tion
a
l sw
itch
i
ng
cycle. Th
e transitio
n
will b
e
v
e
ry fast
, ev
en
dy
nam
i
cal
ly
, due t
o
t
h
e
desi
g
n
of t
h
e t
r
a
n
sf
o
r
m
e
r’s n
u
m
b
er of
t
u
rns
-
as
wa
s ex
pl
ai
ne
d be
f
o
re
. D
u
ri
n
g
t
h
e
hal
f
-
b
r
i
d
g
e
op
erati
o
n, th
e conv
erter will h
a
v
e
a du
ty cycl
e (D1
)
. On
t
h
e
o
t
her hand
, t
h
e
pu
sh–p
u
ll
will o
p
e
rate
with
a si
m
ilar, alth
o
ugh
no
t eq
u
a
l,
du
ty cy
cle (D2) (F
i
g
ure 9
)
. Ho
wev
e
r, as th
e d
i
fferen
ce will b
e
small, th
e
d
y
n
a
m
i
c tran
sitio
n
will b
e
v
e
ry fast an
d al
m
o
st n
o
ov
ervo
ltag
e
wil
l
b
e
ob
serv
ed o
n
t
h
e 12
-V o
u
t
p
u
t
.
Furt
herm
ore,
a
s
t
h
e
ot
he
r
o
u
t
put
s a
r
e
po
st
reg
u
l
a
t
e
d,
n
o
ove
r
vol
t
a
ge
wi
l
l
be o
b
se
rv
ed
at
al
l
.
As t
h
e
i
n
p
u
t
vol
t
a
ge
gene
ra
l
l
y
ranges fr
o
m
190 t
o
2
65
V rm
s, t
h
e detec
t
i
on ci
rcui
t
m
u
st wai
t
m
o
re t
h
an 1
0
m
s
to det
ect
a
real m
a
in
s failu
re. If no
t, it ju
st cou
l
d
b
e
a sm
a
ll v
o
ltag
e
ch
ang
e
o
n
th
e
main
s b
u
t
n
o
t
a real failu
re.
Th
en
,
d
u
ring
th
at time th
e en
erg
y
sto
r
ed
on
th
e in
pu
t b
u
l
k
cap
acito
r m
u
st be ab
le to
k
e
ep th
e o
u
t
pu
t v
o
ltag
e
p
e
rfectly regu
l
a
ted
(Figu
r
e
9).
Howev
e
r, th
is cap
acito
r
will h
a
v
e
a
u
s
u
a
l valu
e for an
ac/d
c
conv
erter
with
th
e con
v
e
n
t
io
n
a
l ho
ld-u
p
t
i
m
e
speci
fi
cat
ions a
n
d i
t
do
es
not
need t
o
be
ove
r di
m
e
nsi
o
ned
.
I
n
o
u
r
cas
e, a 2
00 µ
F
(
4
5
0
V
rat
e
d
)
cap
aci
t
o
r
was
u
s
ed.
W
i
t
h
th
is so
lu
ti
o
n
, lo
w
vo
ltag
e
M
O
SFETs can
be u
s
ed
fo
r t
h
e
p
u
s
h–
pu
ll,
wh
i
c
h
is m
u
ch
op
ti
m
i
zed
.
Th
erefo
r
e, th
e
p
e
rform
a
n
ce o
f
th
is co
nv
erter will b
e
q
u
ite g
o
o
d
. No
te that th
e cu
rren
t
l
e
v
e
ls will b
e
really
high
because the full
200-W output powe
r will be
obtained from
th
e 12-V
battery and th
e
n
dri
v
en by
the
pus
h–pull.
Thi
s
is im
portant
because
the
be
tter the e
fficie
n
cy
of
the
UP
S is, the longe
r the autonom
y will
be.
A
pa
rt
f
r
om
t
h
e m
a
i
n
powe
r
st
age, t
h
e
po
wer s
u
ppl
y
ha
s
anot
her i
nde
p
e
nde
nt
ac/
dc c
o
n
v
e
r
t
e
r t
o
o
b
t
a
i
n
t
h
e
+5
VSB
vol
t
a
g
e
. AT
X
speci
fi
cat
i
ons as
Ta
bl
e 2
defi
ne t
h
i
s
out
put
a
s
a st
a
n
d
by
v
o
l
t
a
ge t
h
at
m
a
y
be use
d
t
o
po
we
r ci
rc
ui
t
s
t
h
at
re
qui
r
e
po
wer
i
n
put
d
u
ri
ng
t
h
e
p
o
we
re
d-
d
o
w
n
st
at
e
o
f
t
h
e
p
o
w
er
rai
l
s
.
Tab
l
e 2
.
Vo
ltag
e
an
d
cur
r
e
n
t
r
a
tin
g
of
an
ATX
po
w
e
r
supp
ly.
Output
Voltage
Cu
rren
t
(a
m
p
s
)
12 V
6 A
5 V
16 A
3.
3 V
14 A
-
12 V
0.
3 A
-
5
V
0.
5 A
+5VSB 0.
8
A
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 2, A
p
ri
l
20
15
:
23
1 – 2
4
2
2
39
W
i
t
h
o
u
r c
o
n
f
i
g
u
r
at
i
o
n, i
t
i
s
not
p
o
ssi
bl
e t
o
po
wer
one
vo
l
t
a
ge rai
l
and
not
an
ot
h
e
r;
as
a conse
que
nc
e, an
in
d
e
p
e
nd
en
t
co
nv
er
ter
is n
e
ed
ed. I
n
ou
r
case,
a v
e
r
y
sim
p
le
f
l
y-
b
ack
co
nv
er
ter
w
a
s d
e
sign
ed
u
s
ing
a
top
switch
and
,
i
n
o
r
d
e
r to
m
a
k
e
g
ood
u
s
e
o
f
it, th
e au
x
iliary
v
o
ltag
e
fo
r th
e con
t
ro
l circu
i
t
r
y was also
obtain
e
d
fro
m
th
is co
nverter.
Fig
u
r
e
10
. Ef
f
i
cien
cy of
th
e syn
c
hr
ono
u
s
buck
co
nv
er
ter
(a) Ou
tpu
t
vo
ltag
e
:
5
V, (b) Ou
tpu
t
vo
ltag
e
: 3
.
3
V
Fig
u
r
e
11
. Ef
f
i
cien
cy of
th
e half
-
b
r
i
dg
e con
v
er
ter
an
d th
e syn
c
hro
nou
s
b
u
c
k
co
nv
er
ter
s
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
DC UPS fo
r Critica
l
Loa
d
s
(
G
a
n
es
h S)
24
0
Wh
en
t
h
ere is a m
a
in
s failure, t
h
e en
erg
y
is ob
ta
in
ed
fro
m
th
e b
a
ttery an
d hen
c
e,
th
is on
e is
di
scha
rge
d
.
E
v
i
d
ent
l
y
, a
bat
t
e
ry
cha
r
ge
r s
h
o
u
l
d
be i
m
pl
em
ent
e
d i
n
or
der
t
o
rec
o
v
e
r t
h
e
ener
gy
u
s
ed
an
d
get
t
h
e bat
t
e
ry
rea
d
y
f
o
r
t
h
e
ne
xt
fai
l
u
re
.T
he
ba
t
t
e
ry
char
ger
i
m
pl
em
ent
e
d i
n
t
h
e
pr
ot
ot
y
p
e
i
s
ve
ry
si
m
p
l
e
. A
no
n-
tig
h
tly regu
lat
e
d
d
c
vo
ltag
e
i
s
ob
tain
ed
from
a win
d
i
ng
co
up
led to th
e filter in
du
ctor.
Th
en
, a sim
p
le
lin
ear
cu
rren
t
regu
lat
o
r is im
p
l
e
m
en
ted
with
a b
i
po
lar tran
sistor
in
or-
d
e
r to
ch
arg
e
th
e b
a
ttery at con
s
tan
t
cu
rren
t
(220
m
A
). Fi
nally, wh
en
t
h
e b
a
ttery is ch
arg
e
d
,
a
h
y
st
eretic co
n
t
ro
l st
rateg
y
is used
to
k
e
ep th
e
b
a
tter
y
v
o
ltag
e
alw
a
ys b
e
tw
een
13
.6
–1
3.1 V.
3.
E
X
PERI
MEN
T
AL RES
U
L
T
S
A pr
ot
ot
y
p
e
h
a
s been f
u
l
l
y
devel
ope
d i
n
or
der t
o
c
h
eck
i
f
t
h
e powe
r
sup
p
l
i
e
s wi
t
h
t
h
e dc UP
S
(in
c
lud
i
ng
th
e 1
2
-V
b
a
ttery) co
u
l
d
fit in
to
an
ATX ch
a
ssis
.
The basic spe
c
ifications of the powe
r supply are
th
e fo
llowing
:
1)
I
n
put
v
o
l
t
a
ge:
1
9
0
–2
6
5
V.
2)
Di
ffe
rent
o
u
t
p
ut
v
o
l
t
a
ges
and
t
h
e m
a
xi
m
u
m
curre
nt
o
f
e
ach
out
put
a
r
e
sho
w
n i
n
Ta
bl
e II
.
3)
I
n
t
e
g
r
at
ed
d
c
UP
S:
7
-
m
i
n aut
o
nom
y
at
ful
l
po
we
r.
4)
M
a
xi
m
u
m
Si
ze:
14
5 ×
1
4
2
×
8
0
m
m
.
5)
O
v
e
r
cu
rre
n
t
and
o
v
e
r
v
o
l
t
a
ge
pr
ot
ect
i
o
n
s
on
al
l
o
u
t
p
ut
s,
PS-
ON
an
d
P
W
-
O
K
si
g
n
al
s.
6
)
Co
m
p
lian
c
e with
EN60
950
.
Fi
gu
re 1
2
. (a)
Ph
ot
o
g
ra
p
h
of t
h
e
DC
U
PS
sy
st
em
wi
t
h
bat
t
e
ry
Fi
gu
re 1
2
. (b
) Ph
ot
o
g
ra
p
h
of t
h
e
i
n
di
cat
or
s of
t
h
e DC
UPS
In
or
der t
o
gi
v
e
som
e
m
odul
ari
t
y
t
o
t
h
e sy
st
em
, t
h
e vol
t
a
ge val
u
e o
f
b
o
t
h +5
V an
d +
3
.3
V o
u
t
p
ut
s
can
be adjuste
d
from
3 to
9
V (80
W m
a
xim
u
m
each).
As m
e
ntioned ea
rlier, these
out
puts a
r
e
obtained from
t
w
o p
o
st
re
g
u
l
a
t
o
rs base
d on
sy
nch
r
on
o
u
s buc
k
c
o
nve
rt
er
s.
T
h
e
t
o
t
a
l
p
o
we
r of
b
o
t
h
out
put
s an
d
t
h
e
1
2
V
out
put
i
s
2
0
0
W.
In
or
der t
o
gi
v
e
som
e
m
odul
ari
t
y
t
o
t
h
e sy
st
em
, t
h
e vol
t
a
ge val
u
e o
f
b
o
t
h +5
V an
d +
3
.3
V o
u
t
p
ut
s
can
be adjuste
d
from
3 to
9
V (80
W m
a
xim
u
m
each).
As m
e
ntioned ea
rlier, these
out
puts a
r
e
obtained from
Evaluation Warning : The document was created with Spire.PDF for Python.