TELKOM
NIKA Indonesia
n
Journal of
Electrical En
gineering
Vol. 16, No. 3, Dece
mbe
r
2
015, pp. 473
~ 479
DOI: 10.115
9
1
/telkomni
ka.
v
16i3.924
3
473
Re
cei
v
ed Au
gust 3, 201
5; Re
vised O
c
to
ber 23, 20
15;
Accept
ed No
vem
ber 1
6
, 2015
A Cascade Multilevel Z
-
Source Inverter for Photovoltaic
System
Thirumalini P, R. Arulmoz
h
i
y
al,
M Murali*
Dep
a
rtment of Electrical & El
e
c
tronics So
n
a
Coll
eg
e of T
e
chno
log
y
, Sa
le
m, India
*Corres
p
o
ndi
n
g
author, e-ma
i
l
: tirumalin
i@g
m
ail.com, aru
l
mozhi
y
a
l
@
g
mail.com,
muralim
unr
aji
@
gmai
l.com
A
b
st
r
a
ct
T
h
is pap
er de
scribes a
mult
ileve
l Z
-
source
inve
rter for solar ph
otovo
l
taic ap
plic
ation
s
. T
h
e
conve
n
tio
nal
p
o
w
e
r conv
ersi
o
n
top
o
l
ogy
perf
o
rms
e
i
ther
bu
ck or
bo
ost the
in
put v
o
ltag
e f
o
r n
o
n
li
near
l
o
ad
dep
en
din
g
u
p
o
n
d
u
ty ratio
an
d
mod
u
l
a
tion
in
dex i
n
a
multi
p
l
e
stag
e co
nver
sion w
i
th th
e
h
e
lp
of i
m
p
e
d
a
n
c
e
source p
a
ssive
netw
o
rk (L and C), w
h
ich is
usua
lly k
now
n
as Z
-
Source, w
h
ich coup
les
the n leve
l sou
r
ce
w
i
th input to
th
e pow
er s
ourc
e
an
d i
n
cre
a
se
the p
o
w
e
r effi
ciency. The
multilev
e
l
z
netw
o
rk cap
a
b
iliti
e
s
of
inverter
are
op
erated
in t
he s
hoot thr
oug
h st
ate of d
u
ty cyc
le a
nd
it acts a
s
a filter to
red
u
ces th
e l
e
vel
o
f
har
mo
nics, sta
b
ili
z
e
p
o
w
e
r factor and to
inc
r
ease th
e
out
p
u
t AC volta
ge
rang
e of inv
e
rter. T
o
overco
me
further h
a
r
m
on
ics, multil
evel
level
o
perati
o
n
z
sour
c
e
inv
e
rter co
mpens
ates the
fun
d
a
menta
l
l
e
vel
of
har
mo
nic i
n
r
enew
ab
le. Pro
pose
d
w
o
rk a
s
a w
hol
e i
n
v
o
lves th
e si
mulati
on
part to
desi
gn
multil
ev
e
l
inverter. T
he o
u
tput of the si
mu
lati
on is
obt
ain
ed by Si
mu
li
nk mo
de
l usin
g
MAT
L
AB.
Ke
y
w
ords
:
Z source inverter, Photo voltaic syst
em
, total harm
onic dist
ortion (THD)
Copy
right
©
2015 In
stitu
t
e o
f
Ad
van
ced
En
g
i
n
eerin
g and
Scien
ce. All
rig
h
t
s reser
ve
d
.
1. Introduc
tion
Ren
e
wable e
nergy
sou
r
ce
s natu
r
ally av
ailable,
such
as
wind, ph
otovoltaic (PV
)
and fuel
cell a
r
e b
e
c
omin
g mo
re nee
ds fo
r indu
strial
and resi
dent
ial appli
c
atio
ns. Nowada
ys,
Photovoltaic
cell
s are u
s
e
d
in wide
sev
e
ral a
r
ea
s
du
e to it’s very often mainten
ance, free fro
m
pollution an
d
zero fuel
co
st. In prese
n
t
scen
a
rio th
e energy ge
neratio
n thro
ugh PV cell has
gro
w
n ra
pidly
from 40% to
45% per an
n
u
m over t
he past 20 yea
r
s that is mostly becau
se of the
co
sts in PV
cell
s than
ks
nano
-technol
ogy field
whi
c
h h
a
s
re
du
ced PV pan
el
s a
s
for
co
st
and
area
st
ru
cture is con
c
e
r
n [
1
-2]. Th
e
con
v
erter
and
in
verter are
oth
e
r promi
nent area
whe
r
e h
a
s
sola
r
and
win
d
en
ergy
ge
n
e
ration
is b
e
i
ng p
r
o
c
e
s
sed
used
by u
s
e
r
s commu
nity. Due
to
re
ce
nt
developm
ent
s in
po
we
r el
ectro
n
ics te
chnolo
g
y inverter a
nd
conv
erter g
r
ows leap
s a
nd
bo
und
s
in term
s of ef
ficien
cy. Z so
urce type of i
n
verter
pe
rforms effici
ent p
o
we
r tra
n
sfe
r
betwe
en d
c
t
o
ac. In a
conv
entional Z
so
urce inve
rter t
he two
switch
es of the
sa
m
e
-ph
a
se leg
a
r
e be
trigg
e
re
d
at
the same
time
be
ca
use this cau
s
e
a sho
r
t
ci
rcuit whi
c
h woul
d destroy
the switch
es
life
ti
me
[3].
In the centra
lized configu
r
ation, a num
ber
of PV module
s
are conne
cted Z
sou
r
ce
inverter
usi
n
g
indu
ctan
ce
a
nd capa
citan
c
e valu
es [4-5]. The Z
so
u
r
ce
inverte
r
solution e
m
plo
y
s
the oppo
site
approa
ch by usin
g a sm
all inverter
for i
ndividual MP
P tracki
ng of each PV mod
u
le,
maximizin
g
p
o
ssible e
nerg
y
harvesting.
Therefore,
re
duci
ng or eve
n
losin
g
the o
u
tput of a sin
g
le
z
sou
r
ce inve
rter
ha
s a
mi
nimal im
pa
ct
on the
ov
e
r
a
l
l s
y
s
t
em pe
r
f
or
ma
nc
e
.
H
o
we
ve
r
,
th
e ma
in
drawback
of t
he inverter
c
o
nc
ept is
a
higher in
itial
equipment
c
o
s
t
per peak watt. In PV s
y
s
t
ems
,
su
ch
as re
si
dential
appli
c
ations, th
e i
n
verter pr
i
c
e
ha
s le
ss eff
e
ct o
n
the
o
v
erall
co
st, a
n
d
therefo
r
e, Z
source
inverte
r
s are th
e p
r
e
f
erre
d
so
lutio
n
. As th
e
pri
c
e of Z
sou
r
ce
inverte
r
com
e
s
down, this technolo
g
y will be more a
ttractive in other application
s
[6].
In addition, the relia
bility of the inverter is
for effecti
v
e solar p
o
wer gen
eration
due to
sho
o
t throu
g
h
state cau
s
ed in Z sou
r
ce pa
ram
e
ters by Electro
Magneti
c
Interferen
ce (E
MI)
noise
can
d
e
stroy
the
ci
rcuit
for lon
g
e
r
peri
o
d
s
[7
]. The a
p
p
r
o
p
riate
switchi
ng p
e
rmit
s t
h
e
addition
of ca
pacito
r
voltag
es o
r
ind
u
cto
r
in t
he outp
u
t port. Thi
s
to
pology results in hi
gh volt
age
gene
ration
wi
thout stre
ssin
g the se
mi
co
ndu
ctors co
m
pone
nts. Z so
ur
ce inverte
r
has a
d
vantag
es
in multi-levels has the follo
wing me
rit: (i) sinu
soidal
o
u
t
put waveform, (ii) a efficient filter size
and
(iii) a minimi
zed EMI.
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 16, No. 3, Dece
mb
er 201
5 : 473 – 479
474
The m
a
in
a
d
vantage
of
usin
g Z
source i
n
verte
r
i
s
to
re
du
ce
the T
o
tal
Harmo
n
ic
Disto
r
tion
(T
HD) from
so
urce e
s
p
e
ci
al
ly like th
i
r
d a
n
d
seventh
o
r
de
r ha
rmo
n
i
c
s in the
out
put
voltage b
e
ca
use
of multi
p
le voltag
e l
e
vels
sw
itchi
ng semi
con
d
u
ctor
redu
ce
s stre
ss
on
the
swit
chin
g dev
ice
s
[8]. Multi gene
ration
PWM
strat
egy is
a widely
a
d
opted
in mod
u
lating strate
gy
for inverter. It is like the si
nusoi
dal PWM strategy [9
]. Multicarrie
r
PWM is on
e in whi
c
h, sev
e
ral
cycle
of
tria
n
gular ca
rrie
r
sign
als
a
r
e compa
r
ed wi
th
one cy
cle of
sinu
soid
al m
odulatin
g
sig
n
al.
The nu
mbe
r
of ca
rrie
r
s
are ne
ce
ssary to pro
d
u
c
e
m
-level output i
s
(
m
-1
). All c
a
rri
er
s hav
e
t
h
e
simila
r pea
k to pea
k amplit
ude Ac an
d freque
ncy fc [1
0].
The mai
n
obj
ective of this pape
r is to i
m
pl
eme
n
t multilevel z-so
urce invert
er
with the
grid interfa
c
i
ng sola
r po
wer gen
eratio
n
system
as b
l
ocks sho
w
n
in Figure 1. The functio
n
of
multilevel z-source inve
rte
r
is to
synthe
sis
a de
cid
e
d
output a
c
vol
t
age from
sev
e
ral level
s
of
dc
input voltage
with minim
u
m harm
oni
c disto
r
tion.
The mag
n
itu
de of output
ac voltage
o
f
conve
n
tional
inverter i
s
limited to dc so
u
r
ce volt
ag
e a
nd with mo
re
harmo
n
ic di
stortion and th
is
limitation can
be
re
solved
by ca
scad
ed
multilevel
z-source i
n
verte
r
. The
propo
sed multilevel
z-
sou
r
ce invert
er shoot
s through to bo
ost dc link volta
g
e. A compa
r
ison a
nalysi
s
has b
een m
a
de
with conventi
onal
z-sou
r
ce
and mu
ltilev
e
l
z-so
urce n
e
twork
in mat
l
ab
sim
u
lin
k environ
m
ent and
its perfo
rman
ce ha
s be
en
analysed u
s
in
g real time co
ntrolle
r.
Figure 1. Block di
agram of
propo
se
d sy
stem
2. Photov
oltaic
Cell
The equival
e
nt model of a photovoltaic
cell can be repre
s
e
n
ted b
y
Figure 2 a
s
sho
w
n
belo
w
. To obt
ain maximum
powe
r
from
sola
r are con
n
ecte
d in seri
es o
r
in pa
rall
el, which forms
a mod
u
le. Ag
ain, the
s
e typ
e
s
of mod
u
le
s a
r
e
co
nne
cted in p
a
rall
el
or i
n
seri
es t
o
get
req
u
ire
d
voltage an
d
curre
n
t. The
cha
r
a
c
teri
stics of PV
cell
can
be
de
rived u
s
ing
the
equ
ation giv
e
n
belo
w
.
I
Ip
v
Ioe
1
(1)
W
h
er
e I
pv
= photo voltai
c cu
rrent, I
0
= Nil
or saturation
c
u
rrent, V
t
= N
s
k
T
/q, array thermal
voltage, N
s
=
pv cell co
nn
ected in
se
ri
es, T = PV panel di
ode t
e
mpe
r
ature, k = con
s
tant
o
f
Boltzman
n, q = elect
r
on
charg
e
, R
s
= e
quivalent re
si
stan
ce of the
seri
es
con
n
e
cted a
r
ray, R
p
=
equivalent
l
resi
stan
ce of parall
e
l con
n
e
cted
array,
a = ide
a
lity consta
nt of di
o
de. Th
e resi
st
ance
c
o
nn
ec
te
d
in s
e
r
i
es
(R
s)
can be re
gulat
ed from the value of shu
n
t resi
stan
ce R
p
either high
or
low when
co
mpared to the value of series re
si
stan
ce
R
s
.
Figure 2. Photo Voltaic
cell
equivalent ci
rcuit
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
A Cascad
e M
u
ltilevel Z
-
So
urce Inve
rter
fo
r Photovoltaic System
(Thirum
a
lini P)
475
The
saturation current
g
enerated
by the light i
s
linea
rly dep
end
s up
on t
he sola
r
irra
diation f
r
o
m
su
n a
nd te
mperature
which, infl
u
e
n
c
e the g
ene
rat
i
on of p
hotov
oltaic
cu
rre
nt in
the sola
r cell
whi
c
h is d
e
riv
ed by the followin
g
equati
on.
Ip
v
Ip
v,
n
K
I
∆T
(2)
Whe
r
e I
pv
= curre
nt gene
rati
on of photo voltaic
cell at the nomin
al condition (25
ᵒ
C and W/m
2
),
∆
T
= T –
Tn, T
= temp
eratu
r
e in
actu
al condition [K], T
n
= n
o
minal
temperature
[K], K
I
= cu
rre
nt
coeffici
ents of
PV cell, G = irra
di
ation of the device su
rface [W/m
2
], G
n
= nomin
al irra
diation.
2.1. DC – DC Boos
t Conv
erter
The po
wer g
e
nerate
d
by the PV panel fed in to
converter for dome
s
tic use
r
appli
c
ations.
The po
we
r o
b
tained from
PV source i
s
unre
gulat
e
d
and requi
red
to maintain o
p
timum outp
u
ts
from the converter. T
he
energy
will fed to the load
with the du
al stage
power el
ectroni
c system
comp
ri
sing
a
s
conve
r
ting
medium
to b
oost
po
wer a
s
type
of
DC-DC converte
r and
inve
rter.
In
orde
r to
mai
n
tain a
co
nst
ant voltage t
o
the lo
ad, a
DC-DC ste
p
up
conve
r
ter is int
r
od
uce
d
in
pro
c
e
ss
of powe
r
gen
eration. T
he Phot
ovoltaic a
rray
and the inve
rter ne
ed
s m
a
intain con
s
tant
power o
u
tput
to dome
s
tic
con
s
um
ers.
The c
ond
ucti
on mod
e
of the DC-DC converte
r can
be
given by the followin
g
equ
a
t
ion.
(3)
W
h
er
e
D
=
du
ty c
y
c
l
e
,
The value of
the duty cycl
e D will al
wa
ys bet
we
en 0
and 1 an
d h
ence it is imp
o
rtant to
maintain the
output voltag
e highe
r
than
the input voltage in mag
n
itude
3. Z-Sourc
e
Inv
e
rter
An Imped
an
ce inve
rter is terme
d
a
s
Z-source
inverte
r
a
nd th
ro
ugh
its
co
ntrol
m
e
thod to
impleme
n
t op
eration of d
c
-to-ac
po
wer
conversion. Th
e Z-sou
r
ce in
verter is a
uni
que resi
stan
ce
cap
a
cita
nce
and in
du
ctan
ce n
e
two
r
k t
o
deliver
ma
ximum po
wer form solar
module
s
a
n
d
an
inverter
circui
t, the convent
ional Z
sou
r
ce inverte
r
ha
s dra
w
ba
cks o
f
more h
a
rm
o
n
ic di
stortio
n
in
power o
u
tput
s voltage
sag
and swell. T
hus, to ov
ercome drawba
cks in
co
nvent
ional Z sou
r
ce
inverter a mo
dified multilevel conve
r
ter i
s
pro
p
o
s
ed in
this topic.
The tra
d
ition
a
l co
nverte
r failed to h
a
ve
filter circuit
s
to red
u
ce ha
rmonics di
sto
r
tion. The
Z-source i
n
verter ove
r
co
mes the the
o
retical and
hypothetical barriers an
d
rest
rictio
ns o
f
the
traditional vsi
and csi inve
rters as it provides
efficie
n
t powe
r
co
n
v
ersio
n
tech
n
i
que
s. The Z-
sou
r
ce co
nce
p
t is also a bi
dire
ctional
ca
pability in
verting circuit app
lied to all dc-t
o-a
c
, ac-to
-
d
c
,
ac-to
-
a
c
, and
dc-to
-
d
c
po
wer
co
nversi
on with le
s
s
quality is
sues
. Z-s
o
ur
ce inver
t
er
for
dc
-
a
c
power conve
r
sion i
s
efficie
n
t applicatio
n
s
in fuel cell p
o
we
r gen
eration.
Figure 3. Z source Inverte
r
Circuit confi
guratio
n
The Z
sou
r
ce
-re
si
stan
ce-capa
citan
c
e-i
n
ducta
nce n
e
twork i
s
to
cou
p
le the
invert
er
circuit
topology in
multiple ca
scaded
config
u
r
ation
s
to
the
link with po
wer
sou
r
ce a
nd thus p
r
ovi
d
ing
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 16, No. 3, Dece
mb
er 201
5 : 473 – 479
476
uniqu
e con
c
e
p
t ca
scade
d
multilevel fea
t
ure a
s
sho
w
n in Figu
re
3
.
The control
strate
gies
wi
th
the inse
rtion
of shoot
-thro
ugh state
s
in
Z-so
urce inv
e
rter
with LC
filter is analy
z
ed. Th
ere
were
exists two co
nventional in
verter
s, voltage-sou
r
ce inv
e
rter
(VSI
) a
nd current-so
u
rce convert
e
rs
(CSI), to
pe
rform
either re
ctifying or in
vert
ing o
p
e
r
a
t
ion de
pendi
ng o
n
po
we
r flow
dire
ctio
ns.
There are
so
me limitation
s
in the qualit
y of power
o
u
tput with hig
her Total
Ha
rmonic
Disto
r
ti
on
(TH
D
).
Total ha
rmo
n
i
cs di
stortion
affects
overal
l output
of sy
stem. In
spe
c
ific third di
st
ortion i
s
stand
ard
freq
uen
cy of ha
rmonics
which is
gen
erates th
ree
times
of funda
mental frequ
ency
harm
oni
cs in
the sy
stem it
more
severe
than to
creat
e EMI p
r
oble
m
s in
switchi
ng p
a
ttern
s; f
i
ve
times the fu
ndame
n
tal is fifth harmon
i
c lead
s
ove
r
heating
with
sag a
nd
swell issue
s
. T
he
harm
oni
cs in
a system
can
be defined g
ener
ally usin
g from the Eq
uation (4
).
(4)
Whe
r
e
fh i
s
the n
u
mb
er of ha
rmo
n
i
c
s an
d fa
c i
s
the
fre
que
ncy of
fund
amental
sy
stem
harm
oni
cs. In dome
s
tic i
n
terface po
wer line
s
high
er orde
r harmonics a
r
e
not given m
u
ch
importa
nce
which
do
es cre
a
te ha
rm to
system.
The
i
m
porta
nt an
d
harm
creatin
g ha
rmo
n
ics i
n
system
are
3
rd
, 5th, 7th,
9th,11
th
an
d
13
th
. The harmonics wavefor
m
s in
g
ene
r
a
l is g
i
ve
n in
Equation (5).
sin
n
ω
t
(5)
Whe
r
e, Vrn i
s
the voltage in rms of pa
rti
c
ula
r
ha
rmoni
c frequ
en
cy (harm
oni
c or p
o
we
r line
)
.
3.1. Opera
t
ion of Z Sourc
e
In
v
e
rter
The Z-so
urce netwo
rk o
perate
s
in “shoot-th
r
ou
gh
zero state” which is po
ssi
ble to
provide th
e u
n
ique b
o
o
s
t-buck op
erat
ion in the aspe
ct of inverter
[6]. The Z-so
urce inverte
r
is
operated in two mod
e
s
wh
ich are bri
e
fe
d belo
w
.
1) Sh
oot thro
ugh m
ode: In
the shoot
-through
st
ate,
switch
S7 i
s
tri
ggered
and
d
i
ode
Da
is off
state. T
he e
quivale
nt ci
rcuit of
sho
w
s
the sh
oot-throug
h state
with
co
rresp
ondin
g
O
N
a
nd
OFF switch
es is sho
w
n in F
i
gure 4. Th
e operational a
nalysi
s
is exp
r
esse
d as:
V
L
=V
C
(6)
V
dc
=V
L
-V
C
(7)
Figure 4. Circuit of shoot throug
h mod
e
2) Non
sho
o
t throug
h mo
d
e
: In non-sh
o
o
t-thro
ugh m
ode
swit
ch S
7
is trig
ge
red
and a
s
with
cap
a
cita
nce
an
d ind
u
c
tan
c
e i
n
pa
rallel a
s
sho
w
n in Fi
gure 5
.
Output of
L
C
filter
netwo
rk
and ind
u
cto
r
voltage ca
n b
e
cal
c
ulate
d
as:
Vin =
Vc
-V
L
(
8
)
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
A Cascad
e M
u
ltilevel Z
-
So
urce Inve
rter
fo
r Photovoltaic System
(Thirum
a
lini P)
477
The boo
st co
efficient facto
r
B
is determ
i
ned by the Modulatio
n Index (MI). Th
e sho
o
t-
throug
h ze
ro
state is affect
s PWM control of the
inverter. As it ge
nerate
s
eq
uivalently the ze
ro
voltage to th
e loa
d
termi
nal a
nd the
cre
a
tes a
sh
oot- th
rou
gh
perio
d varyin
g by mo
dulat
ion
index.
Figure 5. Circuit of shoot throug
h mod
e
In Z-so
urce in
verter is
ca
scaded in to two le
vels to de
sign a m
u
ltilevel-Z-sou
r
ce i
n
verter.
Advantage
s o
f
multi level Z Source Inverter are: (i
) eit
her in
crea
se
or de
crea
se i
n
the voltage
for
PV energy p
r
ocess to the load, (ii) a
s
it elim
inate
s
ord
e
r h
a
rmonics lea
d
s to reduces
the
mismat
ch
of swit
chin
g pat
terns an
d E
M
I disto
r
ti
on
s, (iii
) p
r
ovid
es
ride
-throu
gh du
rin
g
po
wer
quality issu
e
s
like voltage
sags and
swell with
o
u
t need for ad
d
i
tional circuit
s
, (iv) improv
ed
dome
s
tic u
s
e
r
po
we
r facto
r
(PF
C
), (v
) redu
c
ed harm
onic cu
rrent and
di
st
ortio
n
, (vi) redu
ced
comm
on-mod
e
voltage, (vii) ch
eape
r in i
m
pleme
n
ta
tio
n
, (viii) impro
v
es relia
bility and (ix) hig
h
l
y
efficient for cascad
ed stru
cture [7].
4. Simulation
Results
The casca
d
ed sta
ge
multilevel Z
sou
r
ce i
n
verter
wa
s simulate
d
using
MATLAB/SIMULINK to
ol.
The PV
cell
wa
s
de
sign
ed a
nd
sim
u
lated
with t
he h
e
lp
of i
t
s
equivalent
circuit. Temp
erature a
nd irra
diation we
re con
s
id
ere
d
a
s
the chan
gin
g
paramete
r
s to
cha
nge the o
u
tput of the solar cell. Two
PV cells
of 12V and 24V
were ta
ken
as inp
u
t for the
multilevel Z source inverter c
onfigu
r
ation
as per Fi
gure 2.
Figure 6. MATLAB circuit for multilevel
Z sou
r
ce inve
rter
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 16, No. 3, Dece
mb
er 201
5 : 473 – 479
478
The switchi
n
g circuit co
nsists of reve
rse
blocking
switche
s
usi
ng
MOSFETs a
n
d
diode
s
whi
c
h a
r
e ta
ken from
sim
u
l
i
nk lib
ra
ry. A two wi
ndin
g
1
2
V/230V is
u
s
ed to
co
nne
ct the multile
vel
Z source
inv
e
rter to th
e l
oad
sid
e
.
Re
sistive
l
oad
wa
s
con
s
id
ered fo
r the
si
mulation
and
the
swit
chin
g
seq
uen
ce
we
re
provide
d
a
ccordin
g to th
e
ope
ration
de
scribe
d a
bov
e. A 50
Hz,
2
0
V
pea
k voltage
waveform
wa
s o
b
tained
at
inverte
r
outp
u
t. The
simul
a
tion dia
g
ram
of multilevel
Z
sou
r
ce inve
rt
er i
s
sh
own i
n
Fig
u
re
6
an
d the
output
waveforms are sho
w
n i
n
Fi
gure
7
& 8. T
h
e
output wavef
o
rm rep
r
e
s
en
ts
le
ss disto
r
t
i
on comp
ar
ed w
i
th
Z so
u
r
ce
in
ve
r
t
er
and
e
ffe
c
t
ive
TH
D
is mea
s
u
r
ed i
n
Table1
Figure 8. Output curre
n
t of multilevel z-sou
r
ce
inverter
Figure 9. Output voltage
of multilevel z-source
inverter
Table 1. THD analysi
s
of Z-source inve
rters
S.NO INVERTER
THD
%
(VOL
T
A
G
E
)
THD
%
(CUR
RENT
)
1. Z-phase
inverte
r
18.59%
18.80%
2.
Multilevel
z –source inverter
10.89%
4.88%
The voltag
e a
nd current h
a
r
moni
cs rang
e in three p
h
a
se i
n
verte
r
i
s
18.5
9
% an
d
18.80%
respe
c
tively.
Similarly the voltage and
curre
n
t harm
onics ra
nge i
n
z-sou
r
ce in
verter is 1
0
.8
9%
and 10.8
5
% respe
c
tively. By this, the multi z-sou
r
ce inverter fin
d
s to be m
o
re efficient when
comp
ared wit
h
singl
e stag
e z so
urce in
verter.
0
0.01
0.02
0.03
0.
0
4
0.05
0.06
-3
0
-2
0
-1
0
0
10
20
30
ti
m
e
(
s
ec)
i
n
v
e
r
t
e
r
o
/
p
v
o
l
t
ag
e(
V
)
0
0.01
0.02
0.03
0.04
0.05
0.06
-300
-200
-100
0
100
200
300
ti
m
e
(s
ec)
t
r
an
s
f
or
m
e
r
o/
p
v
o
l
t
age(
V
)
85.
3
5
85.
36
85.
37
85.
38
85.
39
85.
4
85.
41
85.
42
85.
43
85
.
4
4
-1
0
-5
0
5
S
e
l
e
c
t
ed s
i
gnal
:
4272
cycl
e
s
. F
F
T
w
i
n
d
o
w
(
i
n
r
e
d
)
: 3
cycl
e
s
Ti
m
e
(
s
)
0
100
200
300
400
500
600
700
800
900
1000
0
1
2
3
4
5
6
7
8
F
r
equenc
y
(H
z
)
F
undam
ent
al
(50H
z
)
=
9.
747
,
T
H
D
=
10.
83%
M
a
g (
%
o
f
F
u
n
dam
e
n
t
a
l
)
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
A Cascad
e M
u
ltilevel Z
-
So
urce Inve
rter
fo
r Photovoltaic System
(Thirum
a
lini P)
479
5. Conclu
sion
A multilevel Z source inverter for PV syst
ems was
sim
u
lated usi
ng
MATLAB/SIMULINK
tool. Thi
s
mul
t
i-rated
sou
r
ce inve
rter
ca
n
have
an
arbi
trary n
u
mb
er
of PV source
s a
nd i
s
able
to
obtain the
m
a
ximum po
ssible po
we
r of
each delive
r
y indep
end
entl
y
. The PV so
urces can b
e
o
f
different
el
ectrical parame
t
ers and
working co
ndi
tions. The mult
ilevel Z
source inverter i
s
respon
sibl
e f
o
r
boo
sting
the voltag
e to
re
quired
out
put level. Z
n
e
twork capa
citors an
d in
du
ctor
on p
r
ima
r
y
side
in inve
rter reali
z
e
soft-switchin
g
ope
ration.
The
cont
rol
scheme
an
d
the
swit
chin
g alg
o
rithm of the prop
osed inv
e
rter
were
de
scribe
d. The
output of inverter is valid
ated
with THD u
s
i
ng MATLAB FFT analy
s
is.
THD of t
he
output wavef
o
rm was
red
u
ce
d to 10.8
5
%
usin
g filter circuits.
Referen
ces
[1]
F
ang Z
hen
g P
eng. Z
-
Source
Inverter.
IEEE
Transactio
n
s On Industry App
l
icatio
ns.
200
3; 39(2).
[2]
T
he Renianss
a
nce of Solar P
o
w
e
r Pa
nels E
nerg
y
B
y
Olatu
n
ji. Adetu
n
ji.
[3]
Sudh
ir Ra
nja
n
,
Sushma Gu
pta, Ganga A
gni
hotri.
Intern
ation
a
l Jo
urn
a
l
of Chem T
e
ch Rese
arc
h
CODEN (USA)
. 2013; 5(2): 99
3-10
02.
[4]
Suresh L, GR
S Naga Kum
a
r, MV Sudarsan, K
Rajes
h
. Departme
n
t of Electrical & Electroni
c
s
Engi
neer
in
g. Vigna
n’s L
a
ra In
stitute of
T
e
chnol
og
y & Scie
n
c
e. Vadlam
udi,
India.
[5]
Muhamm
ad
H
Ras
h
id. P
o
w
e
r El
ectronics
Circuits
Devic
e
s a
nd A
p
p
lic
ations.
2
nd
Edn
.
En
gl
e
w
ood
Cliffs, N.J: Pre
n
tice Ha
ll. 199
3.
[6]
Umesh S
i
n
ha.
Net
w
ork
An
al
ysis
an
d S
y
nt
h
e
sis. Sat
y
a
pr
akasa
n
. 5
th
Ed
n. Ne
w
De
lh
i: Incorpor
atin
g
T
e
ch India Pub
licatio
ns. 19
94.
[7]
Rob
e
rt L, Bo
y
l
estad Lo
uis N
a
she
l
sk
y
.
El
ectroni
cs D
e
vices
and Circ
u
it T
heor
y. Ne
w
D
e
lhi: Pre
n
ti
c
e
Hall of Ind
i
a. 2
000.
[8]
Sajith S
haik, I
Ragh
ave
n
d
a
r. Po
w
e
r Qua
lit
y Im
prov
eme
n
t
of
T
h
ree Ph
ase F
our W
i
re
Distributi
o
n
S
y
stem
Usi
ng
VSC W
i
th
a Z
i
g-Z
ag T
r
ansfor
m
er.
Internati
o
nal
Jour
na
l of
Engi
neer
in
g R
e
searc
h
a
n
d
Appl
icatio
ns (IJERA)
. 2012; 2(
6).
[9]
Nisha K
CR, T
N
Basavar
a
j. Impleme
n
tatio
n
of Im
pedanc
e
Source Invert
er S
y
stem for
Photovo
l
tai
c
Appl
icatio
ns. E
l
ectrical
& E
l
ec
tronics D
e
p
a
rtment, Sa
th
ya
b
a
ma U
n
iv
ersit
y
, Che
nna
i, Ind
i
a. Electro
n
ics
& Commun
i
cati
on De
partment
, Ne
w
H
o
riz
on
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eg
e Of Engine
erin
g, Bang
alor
e, India.
[10] Po
w
e
r F
a
ctor
Correctio
n of
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on-
Lin
ear
Lo
ads Emp
l
o
y
i
n
g
a Sin
g
l
e
Ph
as
e Active P
o
w
e
r
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ilter: Contro
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Strateg
y
, D
e
si
gn Metho
dol
og
y an
d Experim
entatio
n. F
abia
na Pottker and
Ivo Barbi F
ederal Un
iversi
t
y
of Sant
a C
a
tar
i
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a
rtme
nt of El
ectrica
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i
n
eeri
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w
e
r
Electro
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ics Institute.
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l
orian
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p
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[11]
Kanch
an
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aturved
i
, Dr Ami
t
a Mah
o
r, Anu
r
ag
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har
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w
iv
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e
Po
w
e
r F
ilter T
e
chni
ques
f
o
r
Harmon
i
cs S
u
ppress
i
on
in
N
on
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ear
Lo
a
d
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par
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ics
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Evaluation Warning : The document was created with Spire.PDF for Python.