TELKOM
NIKA Indonesia
n
Journal of
Electrical En
gineering
Vol.12, No.6, Jun
e
201
4, pp. 4572 ~ 4
5
7
8
DOI: 10.115
9
1
/telkomni
ka.
v
12i6.543
9
4572
Re
cei
v
ed
De
cem
ber 2
8
, 2013; Re
vi
sed
F
ebruary 26,
2014; Accept
ed March 1
2
, 2014
Multiple-Input Single-Output Wireless Power
Transmission System f
o
r Coal Mine
Duan Zh
ao*, Enjie Ding, Xin Wang
Io
T
Perception
Mine Res
earc
h
Center, Ch
in
a Univ
ersit
y
of Minin
g
an
d T
e
chno
log
y
221
00
8 Xuzho
u
, Jiangs
u, Chi
na, +
86 51
6 83
899
70
5
*Corres
p
o
ndi
n
g
author, e-ma
i
l
: zhaod
ua
n10
27@
163.com
A
b
st
r
a
ct
In Wireless Po
w
e
r Transmissi
on (WPT) systems, the
pro
p
o
r
tion of ener
gy receiv
ed by th
e loa
d
is
critical
an
d the
efficie
n
cy is t
h
e
more
sig
n
ific
ant p
a
ra
meter.
T
he
ma
gn
etic
mu
ltipl
e
i
n
p
u
t a
l
gorit
hms
as w
e
l
l
as many
multi
p
le over
lap
p
i
ng
coils st
ructures
in the trans
mit
t
er side are
pro
pose
d
for the coal
mi
ne Intern
et
of the T
h
in
gs (
IOT
) nodes. Di
fferent ph
ase s
h
ifts case
s for
the in
put si
gna
l w
e
re cons
id
e
r
ed to study
th
eir
effect on the ef
ficiency. Si
mu
l
a
tion res
u
lts sh
ow
ed that
the
axial c
o
mp
one
nt of ma
gn
etic ind
u
ction r
e
sult
e
d
from the
multip
le over
la
ppi
ng
coils
structure
has pr
eferab
le
ho
mo
gen
eo
us
distributi
on
ov
er the traditi
on
a
l
single
input coil. The pro
pos
ed system ac
hieved an
efficiency v
a
lu
e
of
60% for
a rec
e
iver
placed 40c
m
aw
ay from a 4
coils trans
mitter compari
ng t
o
an effi
cie
n
cy
value of 50
%
for the same
distanc
e usin
g
a
singl
e c
o
il
tran
smitter. Si
mul
a
tion r
e
sults s
h
ow
s t
hat the
pr
opos
ed
mod
e
l
is w
e
ll
ad
apte
d
for the
mova
b
l
e
charg
i
ng
mo
de
for the IOT nodes in co
al
min
e
.
Ke
y
w
ords
: w
i
reless p
o
w
e
r transmissio
n
, MISO, internet of the thin
gs, coal
mi
ne
Copy
right
©
2014 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
There are ma
jority of inco
mpatible mo
n
i
to
ring
syste
m
s in coal mi
ne und
ergro
u
nd whi
c
h
make
s t
r
eme
ndou
s
wa
ste
of network re
sou
r
ces.
With
the devel
op
ment of In
ternet of the
Thi
ngs
(IOT), it prov
ide a unified
network plat
form
to integrate su
ch
syst
em
s and al
so provide the
techn
o
logy of
wirele
ss co
mmuni
cation
coverage,
wh
ich m
a
kes th
e pe
rsonn
el
and
equip
m
e
n
ts
perceiving
an
d locating
re
alize
ea
sily in co
al mi
n
e
unde
rg
roun
d.
As a
n
impo
rtant part
of coal
mine m
onitori
ng
system,
L
o
cali
zatio
n
S
y
stem b
a
s
ed
on IOT
is respon
sible
for real-time
lo
cat
i
ng
and tra
c
in
g of the person
n
e
l and e
quip
m
ents, for
e
n
v
ironme
n
t informatio
n awa
r
ene
ss a
s
we
ll as
for the
searching
and
re
scuing th
e p
e
rsons in
dist
re
ss, which i
s
al
so
an i
m
po
rtant gu
ara
n
te
e to
k
e
ep c
o
al mine s
a
fety produc
tion.
Ho
wever, th
e
battery of
wi
rele
ss no
de
s are
en
ergy
constraine
d, e
s
pe
cially fo
r t
he IOT
(Intern
e
t of the Thing
s
)
wirel
e
ss n
o
d
e
s,
which
will cost m
o
re ene
rgy when
sometim
e
s
transmitting a
udio
and
vid
eo d
a
ta. Th
e
r
efore, t
he a
pplication of Wirel
e
ss
Po
wer
T
r
an
smi
s
sion
(WPT
)
technology in coal
mine
w
ill overcome
such problem
s and
ma
ke
sure that all the wi
rel
e
ss
node
s un
de
rgrou
nd
can
keep en
oug
h
energy, even
t
he disa
ste
r
occurre
d
. In orde
r to a
c
hi
eve
the ab
ove g
o
a
ls, thi
s
p
ape
r p
r
ovide
s
a
Multiple
Inp
u
t Single
Outp
ut (MISO)
WPT syste
m
which
can b
e
appli
e
d to coal min
e
IOT. The prese
n
ted
MISO model i
s
a
b
le to achi
eve more tha
n
60%
transmissio
n efficien
cy, by simulation v
e
rificatio
n
. Th
e re
sults
sho
w
that the re
son
ant co
upli
ng
power tran
smissi
on
sy
ste
m
ba
se
d o
n
MISO mod
e
l
are
mo
re
ad
aptable
in
co
al min
e
tha
n
the
traditional SI
SO WPT syst
em.
2. WPT Sy
st
em
In this p
a
rt a
gene
ral
overview ab
out th
e de
sign
ed
wirele
ss po
we
r tran
sfer
syst
em will
be pre
s
e
n
ted.
Figure
sho
w
s the gen
eral
diagram for the de
sign
ed
WPT syste
m
.
An alternative current
(A
C)
power source will be connected
to the transmitter,
whi
c
h
con
s
i
s
ts of
m
u
lti-overl
appi
ng coil
s
that are arra
n
ged
into
symmet
r
ic
dist
ributio
n with
the
sa
me
radiu
s
. T
he
receive
r
i
s
a
s
sume
d to
be
placed
som
e
dista
n
ce a
w
ay from th
e t
r
an
smitter, u
p
to
40cm. The pi
ck-up
coil
s in the
receiver
side
will induce the po
wer from the radiated magnetic
field and po
wer the conne
cted load which can b
e
a mobile or a
noth
e
r po
rtable d
e
vice.
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
Multiple-In
put
Single-O
u
tpu
t
Wirele
ss Power
T
r
an
sm
ission System
for Co
al Mine
(Du
an Zh
ao)
4573
Figure 1. Wireless Power
Tran
sfe
r
System Model
The WPT system co
nstru
c
ted
f
r
om se
veral
trans
m
itter c
o
ils
and
a receiver
coil whi
c
h
they have the same fre
que
ncy by adju
s
ting the in
terrel
ated paramet
ers. Th
e re
so
nan
ce coils a
r
e
in the state
of self-re
s
on
ant to achiev
e the ma
g
net
ic couplin
g [1
]. The efficie
n
cy of the
WPT
system
can b
e
defined a
s
the ratio of th
e received
po
wer in the lo
a
d
resi
stan
ce t
o
the delivere
d
power from th
e electri
c
po
wer so
urce [2, 3].
3. Multiple Input Tran
smitter Stru
ctur
e
The tran
smitter con
s
ist
s
of multi-in
p
u
t coil
s
whi
c
h
are
arra
nged i
n
to
symmetric
distrib
u
tion wi
th the same radiu
s
. And the cover
age a
r
ea is a
s
the traditional
singl
e input coil.
Figure 2. Single Input Stru
cture
a
nd Mul
t
iple Input Structure
De
scribe th
e
mech
ani
sm
innovat
ion
wi
th four coil
s
stru
ct
ure as
an exampl
e. Figure 2
sho
w
s four
coils st
ru
cture
transmitter fo
r mag
netic b
eam formi
ng
comp
ri
sing th
e first mag
n
e
t
ic
indu
ction wit
h
the first p
hase compo
nent of co
il
1, the se
co
n
d
magn
etic i
ndu
ction
with
the
se
con
d
p
h
a
s
e comp
onent
of
coil
2 a
n
d
so
o
n
. The
relation
of ph
a
s
e
s
m
a
y be
i
n
an
ab
sol
u
te
or
relative man
ner. In othe
r words, the
pha
se of coil
1, coil2, coil3
and coil 4 may be set
by a
seri
ou
s of
rel
a
ted valu
es,
or th
e p
h
a
s
e
s
m
a
y be
set by a
r
bitra
r
y
values re
sp
e
c
tively, e.g. the
pha
se
shift could b
e
offse
t
π
/4,
π
/2,
π
and
so
on f
o
r e
a
ch coil. Another
occa
sion i
s
th
at the
pha
se val
ue
can
be
set a
s
a
r
bitrary va
lues sepa
rate
ly. Assum
e
t
hat the
tran
smitter can
se
nse
whe
r
e th
e m
obile
device
con
s
umi
ng
p
o
we
r i
s
. T
h
e
r
efore the
fo
ur
coil
s
stru
cture tran
smitter
transfe
r effective power to
mobile devi
c
e with
the opt
imized o
r
ma
ximized way according to the
locatio
n
of the receiver in t
he sp
ace with
high efficien
cy for WPT system.
Comp
ari
ng with
the
SISO WPT system,
this ma
g
neti
c
field
form
er co
nsi
s
ts of
multiple
overlap
p
ing
coil
s with
different relatio
n
s of p
h
a
s
e
s
, wh
ere
a
s there i
s
o
n
ly one
coil in
the
traditional tra
n
smitter. The
propo
se
d structure pr
ese
n
ts a viable a
nd simpl
e
me
thod to prod
u
c
e
the ma
gnetic
field formi
ng i
n
the t
r
an
smi
tter
which ma
ke
s the
IOT
node
s
ca
n b
e
ch
arged
wh
e
n
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 6, June 20
14: 4572 – 4
578
4574
the tran
smitter move
s in
a ce
rtain
ran
ge. Ho
weve
r, there i
s
onl
y one coil in
the tradition
al
transmitter. T
he tra
n
smitte
r could
not b
e
moved
d
i
sc
r
e
tion
ar
ily, it s
h
ou
ld
b
e
pu
t in
th
e
p
l
ac
e
whe
r
e cente
r
s of the re
cei
v
er and the tr
ansmitte
r sh
o
u
ld be in the
same axe
s
.
4. Sy
stem Model and Effi
cienc
y
Analy
s
is
The tran
sfer
system is
co
nstituted by severa
l transm
itter coils and a receiver coil which
have the
sa
me fre
que
ncy by adju
s
tin
g
inte
rrel
a
ted
pa
ramete
rs.
The
re
son
a
n
c
e
coil
s
are i
n
the
state of
self-reso
nant to a
c
hieve
the e
n
e
r
gy couplin
g [
4
]. Magneti
c
cou
p
ling
circuit is u
s
ed
on
ly
in the
re
ceiv
er a
n
tenn
a.
L
t
,
L
rp
and
L
rs
are
the i
n
d
u
ctan
ce
of th
e tran
smitter,
prim
ary
coil
and
se
con
dary co
il of the recei
v
er sep
a
ratel
y
.
C
t
,
C
rp
and
C
rs
are the compen
satio
n
cap
a
cito
r of the
transmitter, p
r
imary
coil a
nd second
ary coil of
the
re
ceiver
wh
ich
sho
u
ld b
e
adju
s
ted f
o
r
approp
riate value
to ma
ke
th
e syste
m
(tran
s
mitter
and
re
cei
v
er)
wo
rk in
the
re
son
a
n
ce
freque
ncy a
s
sho
w
n in Eq
uation (1
) .
R
t
and
R
rp
a
nd
R
rs
rep
r
e
s
ent the intern
al resi
stan
ce
s of
transmitter and receiver
coils
res
p
ec
tively.
R
L
is th
e
load
re
si
sta
n
ce
of the
re
ceiver coil.
M
t1_2
,
M
t2_2
,
M
t3_2
,
M
t4_2
are the
mutual i
ndu
ctan
ce
betwe
en e
a
ch tra
n
s
mitter
coil
a
nd the
re
ceiv
er
r
e
spec
tively.
M
2_3
is the mutual indu
cta
n
ce b
e
twe
en
the prima
r
y coil and secon
dary coil in the
receiver. Us i
s
the altern
ating cu
rrent po
wer
sup
p
ly wi
th frequen
cy
0
for the trans
mitter.
0
t
t
rp
rp
rs
r
s
11
1
LC
L
C
L
C
(
1
)
Figure 3
sh
o
w
s the
circuit
diag
ram
of
WPT
syst
em with four
c
o
ils
in the trans
m
itter.
Assu
me that
the re
si
stan
ce, indu
ctan
ce
and
cap
a
cita
nce val
u
e
s
a
r
e sa
me in
all
four
coil
s. As
in
[5] four-coil system can a
c
hieve high efficien
cy t
han two-coil
syste
m
due to high
quality factor o
f
th
e
pr
imar
y an
d
th
e se
co
nd
a
r
y
c
o
il. Bec
a
us
e in
ter
n
al r
e
s
i
s
t
a
n
c
e
of s
o
urc
e
is
no
t c
o
n
s
id
er
e
d
in
this WPT mo
del, there is n
o
cou
p
ling in
the tran
smitter.
Figure 3. Wireless Power
Tran
sfe
r
Sy
stem Model of
Four
Coil
s Structure
The ci
rcuit model provide
s
a refere
nce for anal
y
s
is of
the WPT system cha
r
a
c
teristics of
a ma
gneticall
y
cou
p
ling
re
son
a
tor sy
ste
m
[6]. For
th
e sake of
si
mplicity the
crossin
g
m
u
tu
al
indu
ctan
ce b
e
twee
n the transmitte
r and
the se
con
d
a
r
y coil of the
receiver a
r
e
negle
c
ted in t
h
e
followin
g
an
a
l
ysis. Th
en t
he
curre
n
t in
ea
ch
re
so
nant c
i
rc
uit is
determined from (2) to
(7)
b
y
usin
g Kirchho
ff’s voltage law.
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
Multiple-In
put
Single-O
u
tpu
t
Wirele
ss Power
T
r
an
sm
ission System
for Co
al Mine
(Du
an Zh
ao)
4575
t1
t
t
r
p
t1
_
2
s
t
1
I
Rj
L
I
j
M
U
jC
(
2
)
t2
t
t
rp
t2
_
2
s
t
1
IR
j
L
I
j
M
U
jC
(
3
)
t3
t
t
rp
t3
_
2
s
t
1
I
Rj
L
I
j
M
U
jC
(
4
)
t
4
t
t
r
p
t
4_2
s
t
1
IR
j
L
I
j
M
U
jC
(
5
)
rp
rp
r
p
t1
t1
_
2
t2
t
2
_
2
rp
t3
t3
_
2
4
t
4
_
2
r
s
2
_
3
1
0
t
IR
j
L
I
j
M
I
j
M
jC
Ij
M
I
j
M
I
j
M
(
6
)
rs
rs
r
s
L
r
p
2
_
3
rs
1
0
IR
j
L
R
I
j
M
jC
(
7
)
The effici
en
cy of WPT sy
stem model i
s
cal
c
ulat
e
d
in
Equation
(8).
It is obviou
s
t
hat the
efficien
cy is related to mut
ual indu
ctan
ce bet
we
en th
e prima
r
y coil
and the seconda
ry coil, the
se
con
dary co
il and the load coil. Rt, Rrp
,
Rrs, RL an
d
system angu
lar frequ
en
cy
ω
also have an
import effect
on the efficie
n
cy. The valu
e of
M
t1_2
,
M
t
2_2
,
M
t3
_2
,
M
t4_
2
and
M
2_3
g
i
ve the index of
stren
g
th of co
upling b
e
twe
en the pri
m
ary coil
and the
second
ary coil, the se
con
dary coil and
th
e
load
coil, whi
c
h h
a
ve an i
m
porta
nt effect on the
e
fficiency of the
system. The m
u
tual indu
cta
n
ce
is in relatio
n
ship with the
sha
pe of the coil, num
b
e
r
of turns a
nd
relative po
sition of two coi
l
s.
The tran
smitter
stru
cture i
n
this
pap
er
has a p
o
sitiv
e
effect
on
th
e strength
of
cou
p
ling
bet
wee
n
the tra
n
smitt
e
r
and
the
re
ceiver.
Acco
rding to
theo
retical
analy
s
i
s
, efficie
n
cy i
s
in
p
r
opo
rtio
n to
the ope
ratio
n
angul
ar f
r
eq
uen
cy, mutua
l
indu
ctan
ce
and lo
ad
re
si
stan
ce, but i
n
an inve
rse ratio
to inner
re
sistance of the
prima
r
y coil,
the se
co
n
d
a
r
y coil and th
e load
coil. T
he efficien
cy
will
increa
se
sq
u
a
re
times ove
r
the
in
cre
a
se of a
ngul
ar frequ
en
cy. What s
houl
d b
e
pay attentio
n
to
is load resi
st
ance sho
u
ld
match the in
ner resi
stan
ce well to get the maximal powe
r
of the
receiver. The
r
efore, the be
st way to increase t
he efficiency is to rai
s
e the coupli
ng stre
ngth a
s
much
as
po
ssible b
e
twe
e
n
the tran
smitter an
d the re
ceiver. So it i
s
effective way to increase
th
e
numbe
r of turns of the
coil
and its
radiu
s
to incr
ea
se the mutual in
d
u
ctan
ce. But
the numb
e
r o
f
turns an
d radi
us
sh
ould
not
be too
large.
One
re
ason
i
s
the
de
sign
of the coils sh
ould fit the
si
ze
of the portabl
e devices. The other
reason is the resi
stance of t
he coil will also get large whi
c
h
will lead to waste of ene
rg
y.
42
2
to
t
2
_
3
L
t
22
2
tr
p
r
s
r
s
t
o
t
t
2
_
3
22
2
2
2
t
r
p
r
s
r
s
t
ot
t
2_3
tot
r
s
tot
t
1_2
t2_
2
t
3
_2
t4_2
tt
t
t
rp
rp
r
p
rp
rs
rs
r
s
L
rs
4
1
1
1
MM
R
Z
ZZ
Z
Z
M
Z
M
ZZ
Z
Z
M
Z
M
M
Z
M
M
MMM
ZR
j
L
jC
ZR
j
L
jC
ZR
j
L
R
jC
(
8
)
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TELKOM
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KA
Vol. 12, No. 6, June 20
14: 4572 – 4
578
4576
Becau
s
e the
system works o
n
the re
son
ant frequ
ency, then the efficien
cy
can b
e
modified a
s
Equation (9).
42
2
to
t
2
_
3
L
t
22
2
tr
p
R
L
R
L
t
o
t
t
2
_
3
22
2
2
2
tr
pR
L
R
L
t
o
t
t
2
_
3
t
o
tR
L
RL
r
s
L
4
MM
R
R
RR
R
R
M
R
M
RR
R
R
M
R
M
M
R
RR
R
(9)
For th
e sake
of simpli
city the
cro
s
sing
mu
tual in
du
ctance bet
wee
n
the tran
smi
tter and
the seconda
ry coil of th
e
receiver
are
negle
c
t
ed i
n
the followi
ng
analysi
s
. Th
e
n
the p
o
wer
of
WPT syste
m
model is
cal
c
ulated in eq
u
a
ti
on (10
)
by usin
g Kirchho
ff’s voltage law.
24
2
2
to
t
2
_
3
L
2
22
22
t
r
p
r
s
L
r
s
L
t
ot
t
2_3
44
s
VM
M
R
P
RR
R
R
M
R
M
(10)
It is noticed that if the radius of the coi
l
is increa
sed
,
then the distan
ce bet
we
en the
transmitter a
nd the re
ceiv
er ca
n be larger whic
h gu
arante
e
s the
high efficien
cy. Because t
h
e
radius of the coil increases, the efficiency will also be
raised.
5. Param
e
ter
s
Optim
i
za
tion and Sim
u
lation
As is u
s
e
d
for the
wirel
e
ss
device
s
, the
sp
ecifi
c
a
pplication re
quire
ment
s o
f
WPT
system in
co
al mine con
s
train the d
e
si
gn pa
ramete
rs. The diam
e
t
er of tran
smi
tter is no mo
re
than 60 cm a
nd the diam
e
t
er of re
ceive
r
is no
m
o
re t
han 4
c
m. By testing an
d si
mulating many
times, the pro
per an
d optim
ized p
a
ra
met
e
rs a
r
e give
n for the WPT system is sho
w
n in Tabl
e 1
.
Table 1. Opti
mized
Coil P
a
ram
e
ters of Coal Min
e
WPT System
Parameter Valve
Number of
Litz Wire Turns (
N
t)
400
Number of
Litz Wire Turns (
N
p)
400
Number of
Litz Wire Turns (
N
s)
320
Load Resistance
50 ohm
88KHz, AC Cur
r
ent Sauce
0.5A
The receive
r
i
s
a
s
sumed to
be pla
c
ed fro
m
-300
mm to
300mm in
bo
th x axis and
y axis
.
The
dista
n
ce
between
re
ceiver a
nd t
r
an
smi
tter is 400
mm.
The
simul
a
tion d
e
fine
s t
he
transmitter ov
erlap a 6
00m
m × 600m
m a
r
ea.
In Figure 4,
the co
ntou
r
map d
e
scri
b
e
s th
e
area
whi
c
h the
re
ceiver can g
e
t more
efficien
cy. The area ove
r
5
0
% is a circul
ar with radiu
s
of 0.05m.
From the
re
sults, we
can
con
c
lu
de that
4 Co
il
stru
ct
ure tran
smitter is
able to
gene
rate
over 5 W e
n
e
r
gy and ove
r
50% efficien
cy w
hen the re
ceiver i
s
at a 0.2m height.
Figure 4. Re
ceived Powe
r (Unit W) and
Efficiency (Unit %) at 200mm Heig
ht
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TELKOM
NIKA
ISSN:
2302-4
046
Multiple-In
put
Single-O
u
tpu
t
Wirele
ss Power
T
r
an
sm
ission System
for Co
al Mine
(Du
an Zh
ao)
4577
The pha
se
sh
ift of
AC input signal shoul
d be
con
s
id
ered whe
n
usi
n
g 4 Coil structure. In
this part, different inp
u
t signal
s (with same frequ
en
cy and amplit
ude, different
phase
shift) will
be given to
d
i
fferent coil of
the 4
Coil
structu
r
e
s
, whil
e the othe
r
si
mulation p
a
ra
meters a
r
e n
o
t
cha
nge
d.Wh
en give one o
f
the 4 coils
π
/4,
π
/3,
π
/2 a
nd
π
pha
se shifts, the rece
ived power a
nd
efficien
cy con
t
our map i
s
shown in Figu
re 5.
(a) Pha
s
e
shi
ft is
π
/4
(b) Pha
s
e
shi
ft is
π
/3
(c
) Pha
s
e shif
t is
π
/2
(d) Pha
s
e
shi
ft is
π
Figure 5: Efficien
cy wh
en
Coil 2 given
Different Pha
s
e Shift (Unit
%)
Comp
ari
ng Fi
gure 5
(
a
)
to Figure 5
(
d
)
wit
h
Fi
gure 4, it
can b
e
found
that when the
signal
with pha
se
sh
ift is given to
one coil of the 4 coil
struct
ure, the effici
ency will de
crease. The larger
value of the phase shift is, the small
e
r of
the effi
cien
cy is at the cent
er of the tran
smitter.
6. Conclusio
n
In this pape
r,
the desig
n a
nd optimi
z
ation MI
SO mo
del for WPT
system a
r
e d
e
scrib
ed.
Simulation re
sults
sh
ow t
hat sig
n
ifica
n
t
advantage
s of multiple i
nput tra
n
smit
ter in
receiving
efficien
cy. Th
e four coil tra
n
smitter mod
e
l provi
de
a l
a
rge
rang
e, which
can
re
ce
iving high
po
wer
efficien
cy, co
mpari
ng to t
he
single
coi
l
model.
Wh
en u
s
ing
4
coils m
odel
with a 60
0mm
×
600mm tra
n
smitting area, 400mm recei
v
ing distan
ce
and no pha
se shift input signal, the po
wer
transfe
r effici
ency ove
r
60
% is achi
eve
d
for 88K
Hz.
The re
sults
confirm the robu
stne
ss of
the
multi-coils mo
del ba
sed o
n
WPT whi
c
h i
s
well ada
pted
for cha
r
gin
g
the co
al mine
IOT node
s.
Ackn
o
w
l
e
dg
ements
This
wo
rk
was fin
a
n
c
ially su
ppo
rted
b
y
the natio
na
l scien
c
e
an
d technol
ogy
su
ppo
rt
prog
ram of China, und
er G
r
ant No. 20
12
BAH12B01.
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ISSN: 23
02-4
046
TELKOM
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KA
Vol. 12, No. 6, June 20
14: 4572 – 4
578
4578
Referen
ces
[1]
R Ba
nsal.
T
he F
u
ture
of W
i
r
e
less
Ch
arg
i
ng
.
IEEE Antennas and Propagation Maga
z
i
n
e
. 20
09;
51
:
153-
157.
[2]
MSA Kurs. W
i
r
e
less
Po
w
e
r T
r
ansfer v
i
a Stro
ngl
y
Co
upl
ed
Magn
etic R
e
so
nanc
es.
Sci
ence
Mag
a
z
i
ne
.
200
7; 317: 83-
86.
[3]
Mazlo
u
man. M
i
d-ran
ge W
i
r
e
l
e
ss Ener
g
y
T
r
ansfer Us
in
g Inductiv
e
R
e
so
nanc
e for W
i
re
less Se
nsors
.
IEEE International Confer
ence on Com
p
uter Design
. 20
09; 323: 51
7-5
22.
[4]
Can
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gn
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oup
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g as a p
o
t
entia
l me
ans f
o
r
w
i
rel
e
ss po
w
e
r transfer to multipl
e
smal
l
receiv
ers.
IEEE Transactions
on Power Elec
tronics
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9; 24: 181
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825.
[5]
Anil Kum
a
r Ra
mRakh
y
a
n
i. D
e
sig
n
an
d Opti
mizatio
n
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sona
nce-B
a
se
d Efficient W
i
reless Po
w
e
r
Deliv
er
y S
y
ste
m
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ical Imp
l
a
n
ts.
IEEE Transactions
on B
i
om
ed
ical Circ
u
its and Systems
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201
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CM Z
i
erh
o
fer.
Geometric Ap
p
r
oach for
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u
p
lin
g E
nha
nce
m
ent of Ma
gn
eticall
y
Co
up
le
d Co
ils.
IEEE
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r
ansactio
n
s o
n
Bio
m
e
d
ica
l
Engi
neer
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g
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