Internati
o
nal
Journal of P
o
wer Elect
roni
cs an
d
Drive
S
y
ste
m
(I
JPE
D
S)
Vol.
4, No. 4, Decem
ber
2014, pp. 578~
586
I
S
SN
: 208
8-8
6
9
4
5
78
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
/
IJPEDS
Prop
os
ed Volt
age Vect
or to Opti
mize Eff
i
ciency of Di
rect
Torqu
e
Cont
rol
Goh Wee
Yen
*
, Ali
Monadi
*,
Nik
Rumz
i Nik Idris
*
, Au
z
a
ni
Jidin
**,
Tole Su
tikn
o
**
*Department of Electrical
Power
Engi
n
eering
,
U
n
iversiti Teknologi Malay
s
ia (UTM), Johor B
a
hr
u, Malay
s
ia
**
Departm
e
nt
o
f
Power El
ec
tron
ics and
Drives,
Universiti
Tekn
i
k
al Ma
la
ysia
Me
laka
(UTeM),
M
a
la
cca
, M
a
la
ysi
a
*** Departmen
t
of Electr
i
cal
Eng
i
neer
ing, Univer
sitas Ahmad Dahlan (UAD), Yo
g
y
ak
arta, Indonesia
Article Info
A
B
STRAC
T
Article histo
r
y:
Received Aug 22, 2014
Rev
i
sed
O
c
t 26
, 20
14
Accepte
d Nov 6, 2014
Com
p
ared to f
i
eld-ori
e
nted
co
ntrol (F
OC) s
y
s
t
em
, dire
ct
tor
que con
t
rol
(DTC) s
y
s
t
em
has
gained attr
ac
ti
venes
s
in control
drive s
y
s
t
em
becaus
e
of its
simpler control structur
e and faster d
y
namic control. Howe
ver, supply
i
ng the
drive s
y
st
em
with rated flux at
li
ght
load will de
crease th
e powe
r
factor and
effic
i
enc
y
of th
e s
y
s
t
em
. Thus
,
an
optimal flu
x
has been applied durin
g
s
t
ead
y-s
t
a
t
e
in o
r
der to
m
a
xim
i
z
e
th
e eff
i
c
i
enc
y
of drive
s
y
s
t
em
.
But when
a
torque is suddenl
y
ne
eded
, for exam
ple during acce
ler
a
tion
,
the d
y
nam
i
c
of
the torque resp
onse would be degraded
and
it is not suitable for electric
vehic
l
e (
E
V) ap
plic
ations
.
Th
ere
f
ore,
a
modification to
the
voltag
e
vector
as
well
as look-up
table has b
een
pr
oposed in ord
e
r
to improve
the p
e
rformance
of torque respon
se.
Keyword:
Di
rect
t
o
rq
ue c
ont
rol
I
ndu
ctio
n m
a
c
h
in
e
Pro
p
o
se
d vol
t
a
ge vect
o
r
Searc
h
c
ontroll
er
To
rqu
e
r
e
sponse
Copyright ©
201
4 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
:
Nik R
u
m
z
i Nik
Id
ris,
Depa
rt
m
e
nt
of
El
ect
ri
cal
Po
w
e
r E
ngi
neeri
n
g
,
Un
i
v
ersiti Tekn
o
l
o
g
i
Malaysia (UTM),
8
131
0 UTM Sk
ud
ai,
Joho
r
,
Malaysia.
Em
a
il:
nikrumz
i
@fke.u
tm.m
y
1.
INTRODUCTION
A si
m
p
l
e
cont
rol
st
ruct
ure
of
DTC
t
h
at
has
b
een p
r
o
p
o
se
d b
y
Takahas
h
i
[
1
]
has gai
n
e
d
p
o
pul
a
r
i
t
y
i
n
in
du
strial m
o
to
r driv
e ap
p
licat
io
n
s
. Du
e to
it
s si
m
p
ler
co
nt
r
o
l
st
ruct
ure a
n
d fast
e
r
dy
nam
i
c cont
r
o
l
com
p
are
d
to
FOC system
,
th
e p
opu
larity o
f
DTC sy
ste
m
is in
creas
ed ra
pi
dl
y
i
n
t
h
e pa
st
deca
de
s [1
-3]
.
In
FO
C
,
t
h
e
t
o
r
que a
nd
fl
u
x
are co
nt
r
o
l
l
e
d base
d o
n
st
a
t
or cu
rre
nt
co
m
ponent
s w
h
e
r
eas i
n
DTC
,
t
h
e t
o
r
q
ue an
d fl
u
x
are
cont
rol
l
e
d
di
re
ct
l
y
and i
n
de
pe
nde
nt
l
y
vi
a a
n
opt
i
m
i
zed sel
ect
i
on
of
v
o
l
t
a
g
e
vect
o
r
s
usi
n
g
l
o
o
k
-
u
p
t
a
bl
e.
As illu
strated
i
n
Figu
re
1
,
t
h
e
si
m
p
le co
n
t
ro
l stru
cture
o
f
DTC co
n
s
ists
o
f
th
ree-ph
ase
v
o
ltag
e
sou
r
ce
inve
rter (VSI), hysteresis com
p
arator
s, stat
o
r
flux
and
torq
u
e
esti
m
a
to
rs, as well as lo
ok
-up
tab
l
e. By u
s
ing
two-lev
e
l an
d th
ree-lev
e
l
h
y
st
eresis c
o
m
p
arators, the
stator
flux a
n
d
el
ect
r
o
m
a
gnet
i
c
t
o
r
q
ue ca
n
be c
ont
r
o
l
l
e
d
in
d
e
p
e
nd
en
tly. Based
on
l
o
ok-
up
tab
l
e, an
ap
pro
p
r
i
ate vo
lta
g
e
v
ect
o
r
is selected
to
satisfy its flu
x
and
to
rq
ue
requ
irem
en
t. Th
e selected
vo
ltag
e
v
ect
o
r
is t
h
en
app
lied
to activ
ate th
e VSI in
wh
ich
it
will in
tu
rn
o
p
erate
th
e ind
u
c
ti
o
n
mach
in
e.
A fa
st
i
n
st
a
n
t
a
neo
u
s
co
nt
r
o
l
of t
o
r
q
ue a
n
d
f
l
ux
occ
u
rs
bec
a
use
of
de
-c
ou
pl
ed c
o
nt
r
o
l
o
f
t
o
r
q
ue a
n
d
flux
, in
wh
ich
it lead
s to
th
e faster d
y
n
a
m
i
c
co
n
t
ro
l of DTC syste
m
co
mp
ared
to
th
e FOC syste
m
. To
ach
iev
e
m
o
re accurate
flux estim
ation, the
curre
nt model is
ap
plied duri
ng low s
p
eed
operations
whe
r
eas t
h
e
voltage
m
o
d
e
l is e
m
p
l
o
y
ed
in
h
i
gh
sp
eed
op
erations. On
ly stato
r
resistan
ce and ter
m
in
al q
u
a
ntities su
ch
as stato
r
v
o
ltag
e
s an
d cu
rren
ts are
requ
ired
in th
e esti
m
a
t
i
o
n
o
f
vo
ltag
e
m
o
d
e
l.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
Proposed Volt
age
Vector
to
Optimize
Efficiency
of Direct
Torque
Control (Goh Wee
Ye
n)
57
9
Fi
gu
re
1.
Si
m
p
l
e
C
ont
r
o
l
St
ru
ct
ure
of
D
T
C
In
o
r
d
e
r to
fully u
tilized
th
e p
o
wer and
l
e
n
g
t
h
e
n
t
h
e life sp
an
o
f
i
n
du
ctio
n
m
o
to
r,
an
op
tim
a
l
efficiency
of t
h
e drive
system is
an im
po
rt
ant
fact
or t
o
be i
m
pl
em
en
t
e
d i
n
E
V
a
p
pl
i
cat
i
ons.
Us
ual
l
y
,
in
du
ctio
n m
o
t
o
rs are
o
p
e
rated
at lig
h
t
l
o
ad
an
d
t
h
u
s
,
sup
p
lyin
g
th
e m
o
to
r at its rated
flu
x
will d
e
crease the
powe
r factor a
nd e
fficiency
of the
drive [4]. The
r
efore,
researc
h
ers ha
ve bee
n
worki
ng
on the effi
ciency
o
p
tim
izat
io
n
of
d
r
iv
e system
in
recen
t
years
b
u
t
t
h
ere is still n
o
suitab
l
e m
e
th
o
d
to
ach
i
ev
e th
e
fast
instantane
ous t
o
rque re
sponse
of DTC
drive
.
Tw
o m
a
i
n
m
e
t
h
o
d
s h
a
ve
be
en p
r
o
p
o
se
d t
o
m
a
xi
mize e
fficiency in
DTC dri
v
e syste
m
. These
m
e
t
hods a
r
e k
n
o
w
n as fl
u
x
search c
o
nt
r
o
l
l
e
r (SC
)
[
4
-
12]
and l
o
ss m
odel
cont
r
o
l
l
e
r (
L
M
C
) [1
3
-
1
6
]
.
Th
e
form
er
m
e
thod m
easures input power
or stator c
u
rrent
of the system
wh
ile d
e
creasing
th
e
flux
v
a
l
u
e in
a
co
nsecu
tiv
e step
.
When th
e in
pu
t
p
o
wer
o
r
stato
r
curren
t
is at its mi
n
i
mized
v
a
lu
e, th
e
o
p
tim
al f
l
u
x
i
s
obt
ai
ne
d.
M
e
a
n
w
h
i
l
e
,
by
a
p
pl
y
i
ng
l
o
ss
m
odel
eq
uat
i
o
ns
, t
h
e
o
p
t
i
m
al
fl
ux
o
f
l
a
t
t
e
r
m
e
t
hod
i
s
det
e
rm
i
n
ed.
Wh
en
co
pp
er
lo
sses are approx
im
ate
l
y eq
u
a
l to
iro
n
l
o
sses, the
opti
m
ize efficiency of drive sys
t
e
m
is
achi
e
ve
d.
Inst
ea
d of
ju
st
conce
n
t
r
at
e
d
o
n
searc
h
i
n
g fo
r
t
h
e opt
i
m
al
flux
, im
pro
v
i
n
g t
h
e dy
nam
i
c
t
o
rq
ue i
s
al
so
an
essen
tial facto
r
t
o
b
e
co
nsid
ered
in order to
op
timize
the e
fficiency
of DTC system
. This is be
cause
su
pp
lying
th
e
d
r
i
v
e system
a
t
its o
p
tim
u
m
flux
will cau
se th
e t
o
rq
u
e
resp
on
se to
b
e
d
e
g
r
ad
ed
wh
en
a rated
t
o
r
que i
s
s
u
dd
enl
y
neede
d
.
There
f
ore, a
m
odi
fi
cat
i
on t
o
l
o
ok
-
up t
a
bl
e as wel
l
as D
T
C
al
go
ri
t
h
m
has
be
e
n
do
ne
so
t
h
at
t
h
e dy
nam
i
c t
o
rq
ue i
s
ac
hi
eve
d
du
ri
n
g
t
r
a
n
si
e
n
t
st
at
e.
2.
EFFECTS OF
VOLT
AGE VECTO
R
The ef
fect
of
vol
t
a
ge vect
or o
n
t
o
rq
ue
resp
onse
has
been st
u
d
i
e
d
i
n
or
der t
o
im
pro
v
e t
h
e
per
f
o
r
m
a
nce o
f
t
o
rq
ue
res
p
o
n
s
e, as s
h
ow
n i
n
Fi
g
u
re
2
.
B
a
se
d
on
Fi
g
u
r
e
2 (
b
)
,
i
n
sect
o
r
4,
t
h
e v
o
l
t
a
ge
vec
t
ors
,
v
s,5
and
v
s,6
, are applied to increase and dec
r
ease the stat
or
flux
, res
p
ectiv
ely
.
In Fig
u
re
2 (a)
,
v
s,5
is activated
to increase the
stator flux and at th
e sam
e
tim
e, it is capable to incr
ease
t
h
e out
put
t
o
r
que
dy
nam
i
call
y
. B
u
t
activ
atin
g
v
s,6
t
o
dec
r
ease t
h
e fl
u
x
ca
uses t
h
e
out
put
t
o
r
q
ue t
o
i
n
crea
se
sl
i
ght
l
y
, an
d
t
hus
, i
t
de
gra
d
ed t
h
e
to
rq
u
e
p
e
rforman
ce. Th
is case is
worsen
in
g wh
en
t
h
e
flux is set
to its optimized val
u
e
for e
f
ficiency
pu
r
poses
.
In sector
4,
v
s,
5
is conside
r
ed as the m
o
st opti
m
i
zed volta
ge
vector c
o
mpare
d
t
o
v
s,6
because it
has
larg
er tang
en
tial to
th
e stato
r
flux
an
d
co
n
s
eq
u
e
n
tly, it can
p
r
od
u
ce d
y
n
a
micall
y
to
rqu
e
. No
te th
at, at t
h
e v
e
ry
begi
nni
ng
of
s
ect
or
4,
t
h
e
res
p
o
n
se
o
f
t
o
r
q
u
e
i
s
m
o
re dy
na
m
i
c whe
n
v
s,5
i
s
activated for
a longe
r tim
e because
th
is vo
ltag
e
v
e
cto
r
is tang
en
t
i
al to
stato
r
fl
u
x
. Th
erefo
r
e, th
e
vo
ltag
e
vecto
r
t
h
at is ap
p
lied to d
e
crease th
e
st
at
or fl
u
x
has
t
o
be m
odi
fi
ed so t
h
at
t
h
e pro
pos
ed v
o
ltage
vector can produce larg
er tang
en
tial to
stato
r
fl
ux
i
n
o
r
der t
o
i
m
pro
v
e t
o
r
que
pe
r
f
o
r
m
a
nce.
Flux and T
o
r
que E
s
tim
a
tor
s
(
i
.
e
. only
using the voltage
m
odel)
Switching
Tab
l
e
VSI
Sector
T
e
T
e, ref
IM
S
a
, S
b
, S
c
Ψ
s
,
ref
Ψ
s
i
a
, i
b
, i
c
v
a
, v
b
, v
c
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
014
:
57
8 – 586
5
80
(a)
(b
)
Fi
gu
re
2.
V
o
l
t
a
ge
Vect
o
r
(a
) E
ffect
s
o
n
T
o
r
q
ue R
e
s
p
o
n
se
, a
n
d
(
b
)
C
o
nt
r
o
l
l
i
ng
St
at
or
Fl
u
x
3.
R
E
SEARC
H M
ETHOD
A pr
o
pos
ed v
o
l
t
a
ge vect
o
r
i
s
pro
d
u
ced b
e
t
w
een t
w
o con
v
e
n
t
i
onal
v
o
l
t
a
ge vect
o
r
s
by
appl
y
i
n
g
vect
o
r’s
paral
l
e
l
o
g
r
am
l
a
w. C
o
m
p
ared t
o
t
h
e co
nve
nt
i
o
n
a
l
vol
t
a
ge vect
or
, t
h
e pr
o
pos
ed v
o
l
t
a
ge vec
t
or ha
s
l
o
n
g
er am
pl
i
t
ude an
d a
n
an
gl
e of
30
° ad
jac
e
nt
t
o
t
h
e c
o
n
v
ent
i
o
nal
v
o
l
t
a
ge vect
or
. Fo
r
i
n
st
ance, a
d
di
t
i
on
o
f
v
s,5
to
v
s,6
will
o
b
t
ain
v
s,5-6
, as
sho
w
n i
n
Fi
gu
r
e
3,
an
d t
h
ei
r
r
e
sp
ective e
q
uations
are calc
u
l
a
ted in
(1).
,
,
,
,
,
,
1
Fi
gu
re
3.
Vect
or
’s Pa
ral
l
e
l
o
g
r
am
Law
In Fi
gure 4, the red line indicates
t
h
e pr
op
os
ed v
o
l
t
a
ge vec
t
or w
h
er
ea
s the black line re
prese
n
ts the
co
nv
en
tio
n
a
l
vo
ltag
e
v
ect
o
r
. In
pr
opo
sed
m
e
th
od
,
v
s,5-6
is activated instead
of
v
s,6
when t
h
e flux is re
quired to
b
e
redu
ced. Th
e
p
r
o
p
o
s
ed
vo
ltag
e
v
ector
h
a
s a larg
er tan
g
e
n
tial to
stato
r
flux
in
which
it is b
e
liev
e
d to
im
pro
v
e t
h
e t
o
rq
ue
per
f
o
r
m
a
nce w
h
e
n
decr
easi
ng t
h
e fl
u
x
.
In c
o
nve
nt
i
onal
DTC
sy
st
em
, t
h
e swi
t
c
h
i
ng
of
vol
t
a
ge
vect
o
r
i
s
m
o
re reg
u
l
a
r i
n
t
h
e m
i
ddl
e of a s
ector
com
p
ared to t
h
e be
ginning
and e
n
d of a
sector.
C
onse
q
uent
l
y
,
act
i
v
at
i
ng t
h
e
pr
o
pose
d
v
o
l
t
a
ge
vect
o
r
al
so
red
u
ces t
h
e s
w
i
t
c
hi
ng
o
f
v
o
l
t
a
ge
vect
o
r
w
h
en i
t
i
s
in the m
i
ddle
of a sect
or and t
hus
, it inc
r
ease
s
the t
o
rque
dy
nam
i
cally.
30
°
v
s,5
v
s,6
v
s,5-6
Sector
1
Sector
2
Sector
3
Sector
4
Sector
5
Sector
6
Ψ
s
δ
sr
Ψ
r
v
s,6
v
s,5
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S
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208
8-8
6
9
4
Proposed Volt
age
Vector
to
Optimize
Efficiency
of Direct
Torque
Control (Goh Wee
Ye
n)
58
1
Figure 4
Propose
d Volt
age Vector
By ap
p
l
ying
t
h
e pr
opo
sed m
e
th
od
, t
h
e am
p
litu
d
e
o
f
pro
posed
vo
ltag
e
v
e
cto
r
is alm
o
st t
w
ice
o
f
t
h
e
a
m
p
litu
d
e
o
f
co
nv
en
tio
n
a
l meth
od
. Th
e in
creasing
am
p
l
i
t
u
d
e
o
f
vo
ltag
e
v
ector will cau
se th
e v
a
lu
e of stato
r
fl
u
x
an
d
o
u
t
p
u
t
t
o
rq
ue t
o
be
i
n
crease
d
as
w
e
l
l
.
There
f
ore,
t
h
e am
pl
i
t
ude of
p
r
o
p
o
sed
v
o
l
t
a
ge
vect
o
r
c
a
n
be
red
u
ce
d
by
est
i
m
at
i
ng a rat
i
o
bet
w
ee
n
pr
o
p
o
s
ed a
n
d c
o
n
v
e
n
t
i
onal
v
o
l
t
a
ge
vect
o
r
,
as
fol
l
ows:
,
,
2
whe
r
e V
s,k-k
i
s
t
h
e am
pl
i
t
ude of
p
r
o
p
o
se
d
v
o
l
t
a
ge
vect
o
r
a
n
d
V
s,k
is t
h
e
a
m
p
litu
d
e
of co
nv
en
tio
n
a
l
voltag
e
vector.
After in
t
r
odu
cin
g
th
e estim
at
ed
ratio
, it can b
e
seen
th
at th
e d
-
q
ax
is
o
f
p
r
op
o
s
ed
vo
ltag
e
v
ector is
excha
n
ged
wi
t
h
t
h
e d
-
q a
x
i
s
of co
n
v
ent
i
o
n
a
l
vol
t
a
ge vec
t
or. T
h
ere
f
ore,
t
h
e d-
q axi
s
of
pr
op
ose
d
v
o
l
t
a
g
e
vect
o
r
i
s
gi
ve
n
i
n
(
3
)
an
d
(
4
):
,
2
3
0.866
0
.866
3
,
2
3
0
.
5
0
.
5
4
The s
w
i
t
c
hi
ng
st
at
e of
VS
I ca
n
be i
m
pl
em
ent
e
d i
n
t
h
e l
o
o
k
-
u
p
t
a
bl
e wi
t
h
m
odi
fi
ed D
T
C
al
go
ri
t
h
m
si
nce d-
q axi
s
of p
r
op
ose
d
v
o
l
t
a
ge vect
o
r
i
s
excha
nge
d
wi
t
h
d-
q axi
s
of co
n
v
ent
i
ona
l
vol
t
a
ge vect
or
. The
pr
o
pose
d
l
o
ok
-
up t
a
bl
e wi
t
h
m
odi
fi
ed DTC
al
gori
t
h
m
i
s
sho
w
n i
n
Tabl
e
1. In
or
der t
o
im
pro
v
e t
h
e d
y
n
am
ic
o
f
ou
tpu
t
torque, th
e m
o
d
i
fied lo
ok
-up
tab
l
e
with
DT
C algorith
m
is i
m
p
l
e
m
en
ted
on
ly du
ri
n
g
t
r
an
sien
t
state.
Mean
wh
ile, the con
v
e
n
tion
a
l
lo
ok
-up
tab
l
e i
s
app
lied
du
ring
stead
y
-state.
Tabl
e
1
M
odi
fi
e
d
L
o
ok
-U
p Ta
bl
e
Stator Flux
Error Status,
Ψ
s
+
Torque
Error
Sta
t
us,
T
stat
S
ector
1
S
ector
2
S
ector
3
S
ector
4
S
ector
5
S
ector
6
1
1
v
s
,
2
v
s
,
3
v
s
,
4
v
s
,5
v
s
,
6
v
s
,
1
0
v
s
,
0
v
s
,
7
v
s
,
0
v
s
,
7
v
s
,
0
v
s
,
7
-1
v
s
,5
-6
(
v
s
,
6
)
v
s
,
1-6
(
v
s
,5
)
v
s
,
1-2
(
v
s
,4
)
v
s
,
2-3
(
v
s
,
3
)
v
s
,
3-
4
(
v
s
,
2
)
v
s
,4
-
5
(
v
s
,
1
)
0
1
v
s
,
2-3
(
v
s
,
3
)
v
s
,
3-
4
(
v
s
,
2
)
v
s
,4
-
5
(
v
s
,
1
)
v
s
,5
-6
(
v
s
,
6
)
v
s
,
1-6
(
v
s
,5
)
v
s
,
1-2
(
v
s
,4
)
0
v
s
,
7
v
s
,
0
v
s
,
7
v
s
,
0
v
s
,
7
v
s
,
0
-1
v
s
,
5
v
s
,
6
v
s
,
1
v
s
,
2
v
s
,
3
v
s
,
4
Sector IV
v
s,5
v
s,6
v
s,5-6
Hysteresis Ba
nd
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I
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I
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S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
014
:
57
8 – 586
5
82
As sh
o
w
n i
n
Tabl
e 1, t
h
e
r
e
spect
i
v
e p
r
op
ose
d
v
o
ltage vector can
be obta
in
ed
wh
en
th
e
v
o
ltag
e
vector in bracket is act
i
v
at
ed. In ot
her wo
r
d
s,
t
h
e
vol
t
a
ge ve
ct
or
i
n
brac
ket indicates the s
w
itching state of the
respect
i
v
e
pr
o
pos
ed
vol
t
a
ge
vect
o
r
. F
o
r e
x
am
pl
e, i
n
sect
or
1,
v
s,2
is ap
p
lied
to
in
crease th
e flux
and
v
s,2-3
is
activated to de
crease the flux.
Bo
th
o
f
th
ese v
o
ltag
e
v
ect
ors are capable to increas
e t
h
e
out
put
t
o
r
q
ue.
B
u
t
i
n
order to acti
v
ate
v
s,2-3
, the s
w
itching state
of
v
s,3
h
a
s to be imp
l
em
en
ted
.
4.
R
E
SU
LTS AN
D ANA
LY
SIS
The si
m
u
l
a
t
i
on of D
T
C
dri
v
e sy
st
em
has been co
nst
r
uct
e
d
u
s
i
ng M
A
TLA
B
’
s SIM
U
LI
N
K
bl
oc
ks
, as
sho
w
n i
n
Fi
gu
re 5. T
h
e s
p
eci
fi
cat
i
ons a
nd
p
a
ram
e
t
e
rs of i
n
duct
i
o
n m
achi
n
e use
d
i
n
t
h
e sim
u
l
a
t
i
on are
gi
ve
n
in
Tab
l
e 2. The m
o
d
i
fied
look
-up
tab
l
e
with DTC al
g
o
rithm
h
a
s b
een attach
ed in
p
a
rallel to
th
e conv
en
tio
n
a
l
lo
ok
-up
tab
l
e
with
DTC al
go
rith
m
.
Th
e mo
d
i
fied
l
o
ok-
up
tab
l
e with
DTC algo
rith
m
h
a
s
b
e
en
activated
for
5
m
s o
n
l
y du
r
i
n
g
tr
ansien
t st
ate w
h
er
eas
du
r
i
n
g
stead
y-
state, th
e conven
tio
n
a
l l
o
ok-u
p
tab
l
e
w
ith D
T
C
al
go
ri
t
h
m
has
been
i
m
pl
em
en
t
e
d.
Fi
gu
re 5.
Si
m
u
l
a
t
i
on
o
f
DTC
Dri
v
e
Sy
st
em
Tab
l
e
2
Sp
ecification
s
an
d Param
e
ters
of Ind
u
c
tion
Mo
to
r
Param
e
ters
Values
DC vo
ltag
e
3
40V
Stator resistanc
e
,
R
s
0.
25
Ω
Rotor resista
n
c
e
, R
r
0.
2
Ω
Stator i
n
ductance, L
s
0.
09
7
1
H
Ro
to
r ind
u
c
tance, L
r
0.
09
7
1
H
Mutual inductance,
L
m
0.
09
5
5
H
Fre
que
ncy
,
f
50
Hz
In
ertia m
o
to
r, J
0.
04
6
kgm
2
Po
le p
a
irs,
p
2
Sam
p
lin
g
ti
m
e
50µs
Rated
f
l
ux
1.
04
Wb
Rated
to
rqu
e
1
50N
m
In o
r
der t
o
o
p
t
i
m
i
ze t
h
e effi
ci
ency
of d
r
i
v
e
sy
st
em
, t
h
e SC
m
e
t
hod has b
een im
pl
em
ent
e
d i
n
DTC
d
r
i
v
e system
. Th
e
SC is acti
v
ated at t=1
s
w
ith
step
f
l
ux
o
f
0.043W
b
,
sa
m
p
le ti
m
e
o
f
0
.
1
s
and at its r
a
ted
spee
d. Basically, the rate
d
flux is a
pplie
d to
the system
and after t
h
e syst
e
m
has reache
d
its steady-state, the
corres
ponding current val
u
e is
m
easur
ed. Then, the flux is decrease
d
wi
th step flux and the corres
pondi
ng
current value is
m
easured a
g
ain.
Whe
n
the new stator current (I
s, k
) is s
m
aller th
an
th
e pr
evi
ous stator
current
(I
s, k-1
), th
e flux
v
a
lu
e is
d
e
creased wit
h
st
ep
flux
,
and
vice-v
e
rsa.
Th
e SC m
e
th
o
d
is con
tinu
i
ng
un
til it
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I
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S
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:
208
8-8
6
9
4
Proposed Volt
age
Vector
to
Optimize
Efficiency
of Direct
Torque
Control (Goh Wee
Ye
n)
58
3
reaches its opt
i
m
u
m
flux val
u
e. From
Figure
6, the
opti
m
al flux is obtained after
0.3s with
flux value of
0.
89
Wb
.
Fi
gu
re 6.
Fl
u
x
Searc
h
C
o
nt
r
o
l
l
er
3.
1.
V
o
l
t
a
g
e Vect
or
As di
sc
usse
d e
a
rl
i
e
r, t
h
e c
o
n
v
e
nt
i
onal
a
nd
p
r
op
ose
d
v
o
l
t
a
ge
vect
o
r
has
bee
n
p
r
o
v
e
n
i
n
Fi
gu
re
7. T
h
e
bl
ue l
i
n
e i
n
di
c
a
t
e
s t
h
e con
v
e
n
t
i
onal
vol
t
a
ge
vect
or
w
h
erea
s t
h
e red l
i
n
e
d
e
not
es t
h
e
pr
o
pos
ed
vol
t
a
ge
vect
o
r
.
B
a
sed
on t
h
i
s
f
i
gu
re, t
h
e
p
r
o
p
o
se
d v
o
l
t
a
ge
v
ect
or
has sam
e
am
pl
it
ude as t
h
e c
o
n
v
e
n
t
i
ona
l
vol
t
a
ge
vect
o
r
an
d
it is 3
0
° ad
j
acen
t
to
t
h
e con
v
e
n
tio
n
a
l
vo
ltag
e
v
ector.
Fi
gu
re 7.
V
o
l
t
a
ge Vect
o
r
3.
2.
T
o
r
que P
erform
a
nce
In o
r
der t
o
exa
m
i
n
e t
h
e effect
i
v
eness
of p
r
op
ose
d
vol
t
a
ge v
ect
or t
o
w
a
r
d
s t
h
e dy
nam
i
c t
o
rque at
l
i
ght
l
o
ad,
a st
e
p
fl
ux
an
d
t
o
r
q
ue
i
s
ap
pl
i
e
d
f
r
o
m
0.89
Wb
t
o
1.
04
Wb
a
n
d f
r
o
m
0Nm
t
o
1
5
0
N
m
respect
i
v
el
y
at
begi
nni
ng
, m
i
ddl
e a
nd e
nd
of a sect
o
r
, as
sho
w
n i
n
Fi
g
u
re
8. I
n
Fi
g
u
r
e 8 (a
) an
d (
b
)
,
t
h
e st
at
or f
l
ux o
f
propose
d
m
e
thod is i
n
crea
se
d bey
o
nd
rate
d fl
ux
for a
s
h
or
t duration
because d-a
x
is st
ator fl
ux is
slightly
decrease
d
a
n
d
q-a
x
i
s
st
at
o
r
fl
ux
i
s
sl
i
g
ht
l
y
i
n
crease
d
c
o
m
p
ared
t
o
c
o
nve
n
t
i
onal
m
e
t
hod.
Ho
we
ver
,
t
h
e
out
pu
t
to
rq
u
e
is
n
o
t
affected
b
y
th
e slig
h
tly
increas
ed
of stator fl
ux. Mea
n
while,
in
Figure
8
(a), th
e
ou
tpu
t
torq
u
e
is
decrease
d
t
o
120Nm
at t=0.505s
because
th
e flux is
dec
r
ea
sed t
o
its rate
d
value.
v
s,5-6
v
s,1-6
v
s,6
v
s,1
v
s,2-3
v
s,1-2
v
s,2
v
s,3
v
s,3-4
v
s,4
v
s,5
v
s,4-5
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S
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:
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94
I
J
PED
S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
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:
57
8 – 586
5
84
At
b
e
gi
nni
ng
of
a sect
or
, t
h
e
co
n
v
ent
i
o
nal
and
pr
op
ose
d
m
e
t
hod
achi
e
v
e
d t
h
e
rat
e
d t
o
rq
ue i
n
2m
s.
But when a st
ep torque is a
pplied at the
middle of
a s
ector, t
h
e conventional m
e
t
h
od
requ
ir
es
2.8
m
s to
achi
e
ve i
t
s
rat
e
d t
o
rq
ue
whe
r
eas t
h
e
pr
o
p
o
s
ed m
e
t
hod
ne
eds
2.
4m
s t
o
at
t
a
i
n
i
t
s
rat
e
d t
o
r
q
ue. T
h
e
pr
o
pos
ed
m
e
t
hod
has i
m
prove
d t
h
e
per
f
o
r
m
a
nce o
f
t
o
rq
ue
res
p
o
n
se
by
0
.
4m
s com
p
ared
t
o
con
v
e
n
t
i
onal
m
e
t
hod
.
Meanwhile, at
the e
n
d of a
se
ctor,
the
conve
n
tional
and
propos
ed m
e
thod
requires
3.5m
s and
3.
0m
s to reach
t
h
ei
r rat
e
d t
o
r
q
ue,
res
p
ect
i
v
el
y
.
B
y
im
pl
em
ent
i
n
g
t
h
e
p
r
o
p
o
se
d m
e
t
hod,
t
h
e t
o
r
que
res
p
ons
e ca
n be
i
m
pr
o
v
ed
by
0
.
5m
s.
(a)
(b
)
(c)
Fi
gu
re
8
Tor
q
ue Pe
rf
o
r
m
a
nce o
n
(a) B
e
gi
n
n
i
n
g,
(
b
)
M
i
ddl
e, a
n
d (c
) E
n
d
,
of
a Sec
t
or
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
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:
208
8-8
6
9
4
Proposed Volt
age
Vector
to
Optimize
Efficiency
of Direct
Torque
Control (Goh Wee
Ye
n)
58
5
From
Fi
g
u
re
8
(a),
t
h
e
ap
pl
i
e
d
v
o
l
t
a
ge vect
or
i
s
act
i
v
at
ed f
o
r a l
onge
r peri
od si
nce t
h
e v
o
l
t
a
ge vect
o
r
is tan
g
e
n
tial with
resp
ect to
stato
r
fl
u
x
. As
men
tio
n
e
d ear
l
i
er, on
ly th
e
vo
ltag
e
v
ecto
r
that is use
d
to decrease
t
h
e st
at
or fl
ux
i
s
m
odi
fi
ed;
he
nce, t
h
e c
o
nve
nt
i
onal
a
nd
pr
op
ose
d
m
e
t
hod
appl
i
e
d t
h
e sa
m
e
vol
t
a
ge ve
ct
or t
o
increase
flux in which it caus
e
d the c
o
nve
n
tional a
nd
proposed m
e
thod to
reach
rated torque at the
sam
e
tim
e
.
B
a
sed o
n
Fi
gu
r
e
8 (b) a
nd (c
),
i
t
can be seen t
h
at
t
h
e t
o
rq
ue per
f
o
r
m
a
nce i
s
im
prove
d w
h
e
n
t
h
e v
o
l
t
a
ge v
ect
o
r
is activ
ated
fo
r a lo
ng
er p
e
riod
, in wh
ich
it
can
b
e
con
t
ro
lled
b
y
g
e
n
e
rati
n
g
a larger tang
en
tial to
th
e stato
r
fl
u
x
. B
e
si
des t
h
at
,
vol
t
a
ge
v
ect
or t
h
at
h
a
s
larg
er tang
en
ti
al resp
ectiv
e to
stator fl
ux
is ab
le to reduce th
e
swi
t
c
hi
n
g
of
v
o
l
t
a
ge
vect
o
r
.
C
onse
q
uent
l
y
,
i
t
i
s
necessary
t
o
m
odi
fy
t
h
e
an
gl
e o
f
vol
t
a
ge
vect
o
r
s
o
t
h
at
a
d
y
n
a
m
i
c to
r
que can
b
e
pr
oduced
during tra
n
sient state.
5.
CO
NCL
USI
O
N
During
stead
y
-state, th
e fl
ux
h
a
s t
o
b
e
set to an
op
ti
m
u
m
v
a
lu
e in
ord
e
r t
o
op
ti
m
i
ze th
e efficien
cy
o
f
DTC
d
r
i
v
e sy
s
t
em
. Howe
ver
,
t
h
e dy
nam
i
c
of
out
put
t
o
rq
ue w
oul
d be
d
e
gra
d
e
d
w
h
en
a t
o
rq
ue i
s
su
d
d
enl
y
n
eed
ed
and
it is no
t su
itab
l
e t
o
b
e
im
p
l
e
m
en
ted
in
EV
app
lic
a
tio
n
s
.
Th
er
ef
or
e
,
an
adj
u
s
t
me
n
t
to
th
e
loo
k
-up
t
a
bl
e as wel
l
as
DTC
al
g
o
ri
t
h
m
has bee
n
co
nst
r
uct
e
d
by
m
odi
fy
i
ng t
h
e an
gl
e o
f
v
o
l
t
a
ge
vect
o
r
so t
h
at
a
l
a
rge
r
tan
g
e
n
tial with resp
ect to
th
e flux
is yield
e
d
.
Based
o
n
t
h
e resu
lts, it can
b
e
con
c
lud
e
d
th
at th
e prop
o
s
ed
vol
t
a
ge
vect
or
im
pro
v
es t
h
e
p
e
rf
orm
a
nce o
f
t
o
r
que
res
p
ons
e duri
ng t
r
ansient state. T
h
erefore, t
h
is m
e
thod i
s
believed t
o
optimize the efficiency
of
DT
C
dri
v
e sy
st
e
m
and at
t
h
e sam
e
t
i
m
e
, t
h
e dy
nam
i
c of t
o
r
que
r
e
spon
se is imp
r
ov
ed.
ACKNOWLE
DGE
M
ENTS
Th
e au
tho
r
s
wo
u
l
d
lik
e to
exp
r
ess t
h
eir ap
precia
tio
n
to
Un
iv
ersiti Tek
n
o
l
og
i Malaysia
(UTM
) for
pr
o
v
i
d
i
n
g Zam
a
l
a
h’s Sc
hol
a
r
s
h
i
p
an
d M
i
ni
st
ry
of E
ducat
i
o
n f
o
r f
u
nd
rese
arch
gra
n
t
(R
.J
13
0
0
0
0
.
7
82
3.
4
F
3
8
0
)
in
th
is
research.
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