Ci a ion: Vishnu am, P.;
Panchana han, S.; Rajamanickam, N.;
K ishnasamy, V.; Bajaj, M.; Piecha, M.;
Blazek, V.; P okop, L. Re iew o
Wi eless Cha ging Sys em: Magne ic
Ma e ials, Coil Con igu a ions,
Challenges, and Fu u e Pe spec i es.
Ene gies 2023,16, 4020. h ps://
doi.o g/10.3390/en16104020
Academic Edi o : Alon Kupe man
Recei ed: 21 Feb ua y 2023
Re ised: 30 Ap il 2023
Accep ed: 9 May 2023
Published: 10 May 2023
Copy igh : © 2023 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
ene gies
Re iew
Re iew o Wi eless Cha ging Sys em: Magne ic Ma e ials, Coil
Con igu a ions, Challenges, and Fu u e Pe spec i es
P adeep Vishnu am 1, Su esh Panchana han 1, Na ayanamoo hi Rajamanickam 1,
Vijayakuma K ishnasamy 1, Mohi Bajaj 2,3,4,* , Ma ian Piecha 5, Voj ech Blazek 6and Lukas P okop 6,*
1Elec ic Vehicle Cha ging Resea ch Cen e, Depa men o Elec ical and Elec onics Enginee ing,
SRM Ins i u e o Science and Technology, Ka anku hu , Chennai 603203, India
2Depa men o Elec ical Enginee ing, G aphic E a (Deemed o be Uni e si y), Deh adun 248002, India
3G aphic E a Hill Uni e si y, Deh adun 248002, India
4Applied Science Resea ch Cen e , Applied Science P i a e Uni e si y, Amman 11937, Jo dan
5Minis y o Indus y and T ade, 11015 P ague, Czech Republic
6ENET Cen e, VSB—Technical Uni e si y o Os a a, 70800 Os a a, Czech Republic
*Co espondence: [email p o ec ed] (M.B.); [email p o ec ed] (L.P.)
Abs ac :
Elec ic anspo a ion will assis in lowe ing emissions o g eenhouse gases and mi iga ing
he impac o ising pe ol p ices. To p omo e he widesp ead adop ion o elec ic anspo a ion,
a di e se ange o cha ging s a ions mus be es ablished in an a mosphe e ha is iendly o use s.
Wi eless elec ic ehicle cha ging sys ems a e a iable al e na i e echnology ha can cha ge elec ic
ehicles (EVs) wi hou any plug-in issues. Wi eless powe ans e (WPT), which in ol es he
ansmission o elec ici y ia an elec omagne ic ield despi e he p esence o an in e ening a ea,
holds ou he possibili y o new p ospec s o EVs o inc ease en i onmen ally esponsible mobili y.
This e iew a icle examines he WPT echnology and how i migh be applied o elec ic ehicles
om bo h a echnical and sa e y s andpoin . The p ime aim o his e iew is (1) o illus a e he
cu en s a e o he a in e ms o echnological ad ances as well as esea ch limi a ions in he ield o
WPT de elopmen and use wi hin he ield o anspo a ion; (2) o o ganise he expe imen al he
deploymen o WPT EV sys ems in he ac ual wo ld; and (3) o analyse he esul s o e a sus ainable
pe iod and o iden i y limi a ions as well as chances o g ow h. F om a echnical poin o iew, he
p og ess ha has been made on he selec ion o ma e ial o designing coils, di e en ypes o coils
wi h a speci ic ocus on he o e all pe o mance o he sys em. As a esul , his s udy aims o p o ide
an ex ensi e o e iew ocusing on he magne ic ma e ials and he a chi ec u es o he ansmi e
and ecei e pads.
Keywo ds:
wi eless cha ging; cha ging pads; induc i e powe ans e ; magne ic co e; magne ic
shielding; elec omagne ic ield es ing
1. In oduc ion
The ene gy demand has isen a a s a ling a e in ecen yea s, which is only an ici-
pa ed o con inue [
1
]. The mos signi ican p oblem acing con empo a y socie y is he apid
deple ion o ese es o ossil uels, as well as clima e change, en i onmen al p oblems,
and ozone deple ion. Because o his, inc easing he p opo ion o enewable ene gy inco -
po a ed in o ou g id is essen ial o sa is y he e e -inc easing demand o ene gy in he
mode n wo ld. In 2005, non- enewable ene gy sou ces p oduced he as majo i y o he
o al 17,450 TW o ene gy c ea ed. O e he las se e al decades, he excessi e consump ion
o ossil uels o ene gy gene a ion has d ama ically educed a ailabili y. In addi ion o
ha , i is he oo cause o a mul i ude o u he en i onmen al issues. The g eenhouse
e ec is among he mos c i ical issues ha need o be handled, hus which b ings us o he
nex poin . Nuclea powe may o e a solu ion o he p oblem o global wa ming. S ill,
Ene gies 2023,16, 4020. h ps://doi.o g/10.3390/en16104020 h ps://www.mdpi.com/jou nal/ene gies
Ene gies 2023,16, 4020 2 o 31
en i onmen alis s’ esis ance o nuclea powe has ha dened in ecen yea s due o ea s
abou he possibili y o e o is a acks on ea h-bound nuclea powe plan s.
The anspo a ion indus y uses many ossil uels, making i he wo ld’s mos signi i-
can sou ce o g eenhouse gases (GHGs) [
2
]. I is necessa y o de elop al e na i e ehicle
echnologies o educe eliance on ossil uels and g eenhouse gas emissions. Because o
hei bene i s in e ms o o e all pe o mance, educed emissions, and inc eased sa e y,
EVs a e quickly becoming one o he mos p ominen op ions being esea ched igh now.
Howe e , he accep abili y o elec ic ehicles is closely ela ed o he cos o pu chase, he
accessibili y and e iciency o cha ging in as uc u e, and he o al d i ing ange o he
ehicle. Acco ding o he esea ch ha has been conduc ed, he e a e h ee dis inc possi-
bili ies o elec ic ehicle supply equipmen , o en known as cha ging in as uc u e [
3
]:
(1) changing ba e ies, (2) induc i e cha ging, and (3) wi eless cha ging o elec ic ehicles.
When a ehicle is in ol ed in a scena io known as ba e y swi ching, he ba e y swapping
s a ions, also known as BSSs, a e se up o eplace an emp y ba e y wi h a ba e y ha has
been wholly cha ged [
4
]. This app oach p o ides a quick me hod o echa ging (i.e., he
ba e y may be swapped ou in ewe han 5 min). I enables a iable ime o cha ging,
which can be eloca ed o an o -peak pe iod i necessa y. Howe e , he e ec s o cha ging
s a ion swapping on he long- e m heal h o ba e ies, he associa ed cos s, and he s a ions’
p ac icabili y a e s ill up o deba e [4,5].
Al hough conduc i e cha ging echnology p o ides a easible and cos -e ec i e solu-
ion, i has a long cha ging ime (anywhe e om 20 min o eigh hou s). I aises a ew sa e y
issues in ha sh en i onmen s due o he hea y-du y cables and a ew sa e y issues in ha sh
en i onmen s due o he hea y-du y cables ha a e exposed o he public [
6
–
8
]. The hi d
choice is he wi eless powe ans e (WPT) echnology, which allows an elec ic ehicle o
be cha ged wi hou needing any physical connec ion. This can occu whe he he ehicle is
pa ked o an ex ended pe iod (s a iona y). A he same ime, i is being d i en (dynamic o
in mo ion), o du ing b ie s ops (quasi-dynamic o oppo unis ic). Because i is au oma ic,
easy, eliable in ha sh en i onmen s, du able agains espassing, and may be implemen ed
on he oad, in public pa king, p i a e pa king, and a bus s ops, wi eless cha ging o e s a
pe ec op ion o EV cha ging [
9
–
11
]. Wi eless cha ging echnology is an ideal solu ion o
EV imposing because o all o hese easons. In addi ion, he implemen a ion o in-mo ion
wi eless cha ging echnology has a chance o p o ide an unlimi ed ange o d i ing and
ze o down ime, as well as a d ama ic educ ion in he size o he onboa d ba e y. This
esul s in a lowe p ice, smalle size, ligh e weigh o elec ic ehicles, and imp o ed
ope a ional e iciency [
12
]. The echnology o wi eless cha ging has an oppo uni y o
has en he adop ion o elec ic ehicles, which in u n leads o an imp o emen imp o ed
li e o people oday and an imp o ed wo ld o gene a ions o come [13].
The i s e idence o wi eless powe ans e occu ed in he la e 18 h cen u y [
14
–
16
]
when He z demons a ed he p opaga ion o elec omagne ic adia ion in space using a
spa k gap [
17
]. This was he i s ime ha wi eless powe ansmission was success ully
p o en. Nicola Tesla conduc ed expe imen s o see i ansmi ing elec ici y wi elessly ia
adio wa es was possible in 1890. Be ween he yea s 1894 and 1918, he cons uc ed he Tesla
owe , which was a massi e coil wi h a cop in he yea 1960, William B own came up wi h
he idea o a de ice ha would wi elessly anspo sola powe in o space so ha i could
be u ilized o powe spacec a [
18
,
19
] pe ball on he op, o use elec os a ic induc ion o
anspo powe wi elessly [
18
]. In he pe iod be ween 2007 and 2013, a eam o esea che s
om he Massachuse s Ins i u e o Technology (MIT) in oduced Tesla’s heo ies and
expe imen s ha we e based on magne ic esonance coupling o wi elessly anspo
60 W ac oss a dis ance o 2 m wi h an e iciency o 40% u ilising coils wi h a diame e o
0.6 m [
20
,
21
]. Since hen, se e al esea ch g oups wo ldwide ha e begun in es iga ing he
WPT sys em o a ious applica ions, including elec ic ehicles, consume gadge s, cell
phones, compu e s, home appliances, medical equipmen , and elec ic machine y.
Se e al e iews o he IPT sys em ha e been published in he ele an academic li -
e a u e [
5
–
7
,
13
,
20
,
22
]. The majo i y o his esea ch concen a ed on p o iding a gene al
Ene gies 2023,16, 4020 3 o 31
desc ip ion o he echnology, including a ious coil s uc u es [
16
,
22
], a ious compen-
sa ion se ings [
16
], isions o elec ic ehicle cha ging ia Blue oo h [
20
], and his o ical
da a [
11
]. A compa ison o elec ic ehicles’ conduc ion and wi eless cha ging capabili ies
was published in [
6
], conside ing he di e en ypes o EVs, powe le els, ad an ages,
limi a ions, and plans o he indus y. In [
23
], an o e iew o elec ical cha ging echnol-
ogy was o e ed, in which se e al cha ging me hodologies and ela ed s anda ds we e
e iewed. The possibili ies o u ilising induc i e cha ging echnology o elec ic ehicles
we e s udied in [
24
], wi h dynamic as s a ic we land cha ging being conside ed he bes o
he au ho ’s knowledge. The e is no ye a e iew s udy ha concen a es on he layou
o he induc i e pad and desc ibes in de ail he componen s (wi es, co e, and shield) and
subs ances ha ha e been desc ibed. As a esul , his a icle p o ides an exhaus i e and
speci ic e iew o each pa o he wi eless cha ging pad, speci ically he ansmi e , and
ecei e . I in es iga es as well as con as s:
âThe magne ic ma e ial used o ansmi e coil design.
âVa ious elec omagne ic shielding.
âVa ious induc i e pad a chi ec u e wi h i s sus ainabili y
âIssues in he wi eless cha ging sys em
In addi ion, his s udy sheds ligh on se e al di e en wi eless powe sys ems and
discusses he p ope ies o hose echnologies. This s udy gi es an o e iew o he esea ch
conduc ed on WPT, which can assis esea che s in iden i ying subs an ial gaps in he
me hodologies cu en ly being used and a ac ing p ospec s.
The o ganiza ion o he pape is ca ied ou as ollows. Sec ion 2deals wi h WPT
Magne ic ma e ial and coil design. Elec omagne ic ield shielding is explained in Sec ion 3.
Induc i e pad a chi ec u es and hei elec omagne ic s anda ds, wi eless cha ging sys em
sus ainabili y, and social impac s ha e been desc ibed in Sec ions 4and 5, espec i ely. The
issues in wi eless cha ging and u u e pe spec i e a e summa ized in Sec ions 6and 7,
espec i ely. The o e all conclusion o he a icle is enume a ed in Sec ion 8.
2. Magne ic Ma e ial and Coil Design
2.1. An O e iew o So Magne ic Ma e ials
Michael Fa aday disco e ed in 1831 h ough an expe imen ha a cu en would
be gene a ed in he conduc o s o a closed ci cui whene e a sec ion o he conduc o
cu he magne iza ion line inside he magne ic ield. Michael Fa aday disco e ed his. I
was sugges ed ha Fa aday’s law o induc ion should be used [
25
]. Because i has he
la ges sa u a ion magne iza ion o any elemen , i on is selec ed o se e as he co e o he
magne ic s uc u e. In addi ion, i possesses he quali ies o solid pe meabili y and minimal
coe ci i y, bo h ad an ageous. Since ha ime, con inuous p og ess has been made in so
magne ic ma e ials. The esea che s hen obse ed ha he ec ys alliza ion o i on could
inc ease i s mechanical p ope ies and educe i s coe ci i y h ough a p ocess known as
s ess elaxa ion. This was con i med o be he case a e he p e ious inding. As a esul ,
i on is now mo e sui ed o use in applica ions ha in ol e induc ion.
B i ish me allu gis Robe Hud ield in en ed quasi-silicon s eel in 1900 by adding
3% silicon o he i on. This enhanced he ma e ial’s esis i i y and sa u a ion magne i-
za ion [
26
]. G ain-o ien ed silicon s eel was in en ed in 1933 by Ame ican me allu gis
No man Goss. To achie e his esul , he a ou ed g ain g ow h in he di ec ion o low
aniso opic c ys alliza ion, leading o highe sa u a ion magne isa ion le els [
27
]. E en
oday, silicon s eel emains he dominan playe in he in e na ional ma ke o so magne s
due o i s high magne ic momen and compa a i ely low p ice. La ge ans o me s made
ou o o ien a ed silicon s eel a e he mos p e alen applica ion o silicon s eel, ollowed
closely by mo o s (iso opic non-o ien ed silicon s eel). Silicon s eel, on he o he hand,
loses mo e ene gy a highe equencies due o i s low esis i i y (0.5 m
Ω
m) [
21
]. Wi h a
p ocedu e in ol ing chemical apou deposi ion, manu ac u e s o elec ical s eel ha e
ecen ly de ised a echnology ha allows o an inc ease in he silicon con en o he s eel o
6.5% [
28
]. Al hough his echnique can po en ially b ing silicon s eel ma e ials up o 82
µΩ
Ene gies 2023,16, 4020 4 o 31
cm esis ance, i is no ye capable o mee ing he high-e iciency needs o high- equency
powe elec onics and high-speed mo o s.
Gus a Elmen o Bell Labs conduc ed wo k in he 1910s on nickel-i on, which led
o he disco e y o he nickel- ich (78%) pe malloy mix u e [
29
]. One o he pe malloy’s
mos no able bene i s is i s high ela i e pe meabili y (up o 100,000). Nickel-i on is s ill
u ilized in a ew unique induc ion applica ions in oday’s mode n wo ld; howe e , due o
i s signi ican eddy cu en loss, nickel-i on is no ypically u ilized in powe elec onics
o mo o s. Adding nickel can dec ease so magne ic ma e ials’ sa u a ion magne ic lux
densi y. Moly based on di e en pa ame e s powde (MPP) could be c ea ed by inco -
po a ing 2% molybdenum in o he pe malloy manu ac u ing p ocess, as s a ed in [
30
].
MPP is u ilized o ab ica e he powde ed co es wi h a mino loss [
31
], and i emains he
bes op ion o high- equency induc ance co es inside he equency band o 450 kHz
and abo e.
Then, owa ds he end o he 1940s, J. L. Snoek de eloped so magne ic e i es [
32
].
Due o he high esis i i y o hese ma e ials, hey can e ec i ely educe eddy cu en loss.
In addi ion, p epa ing e i e is o en ela i ely s aigh o wa d, allowing he e i e co e
o be manu ac u ed a a compe i i e p ice. So e i e is inc easingly used in elec omag-
ne ism and high- equency equipmen because i has a high esis i i y and good economic
pe o mance. Nowadays, e i e is second only o silicon s eel shee s ega ding ma ke
sha e among so magne ic ma e ials wo ldwide [
33
]. The WPT sys em also ex ensi ely
uses manganese zinc e i e, making i he mos popula so magne ic ma e ial. Howe e ,
he powe densi y o senso de ices con aining e i e co es is cons ained by e i e’s low
sa u a ion lux densi y (almos a ac ion o Si s eel shee s). Because o his, he p og ession
o he e imagne ic p ocess has always been aimed a aising he high sa u a ion lux o
so e i e.
The e y i s polymo phic so magne ic alloy was desc ibed by Duwez and Lin in
he o m o disc-shaped samples [
34
] in 1967. To solidi y Fe-P-C sys ems quickly, hey
adop ed a p ocess e med spla cooling. By he middle o he 1970s, in e es had isen in
amo phous alloys based on Fe and Co. The highe coe ci i y and maximum magne ic
densi y o amo phous alloys compa ed o e i e led o hei adop ion in se e al p ac ical
con ex s. Compa ed o e i e, amo phous alloys ha e be e conduc i i y and sa u a ion
magne ic densi y, gi ing hem some uses. In 1988, Hi achi esea che s indica ed Nb and
Cu and added an annealing s ep o making amo phous alloys. This made small i on o
cobal -based nanoma e ials (abou 10 nm in diame e ) ha we e e enly dis ibu ed in
he amo phous ma e ials. This was he i s ime nanoc ys alline alloys we e made [
35
].
Nanocomposi e and nano-c ys alline alloys ha e educed powe loss and a compe i i e
concen a ion lux densi y. E en hough hey cos mo e han silicon s eel, hese ad anced
alloys can lowe he cos o powe elec onics and mo o s o e hei li e imes because hey
lose less powe .
By he beginning o he 1990s, he concep o powde co es, commonly e e ed o
as magne ic ma e ials composi e o SMCs, was pu o wa d [
36
]. These ma e ials begin
wi h magne ic pa icles anging in diame e om 0.1 mm o 500 mm. They hen coa
o mix hose wi h an insula ing laye be o e solidi ying hem unde high p essu e. In
addi ion, he hea ing p ocedu e can be u ilised ei he du ing o a e he densi ica ion
s age o enhance he magne ic cha ac e is ics o he ma e ial. The i on powde ha makes
up magne ic pa icles is almos always p esen , al hough magne ic pa icles can also be
made o alloys. Powde magne ic co e can be easily ea ed in o a mo e complica ed shape,
inc easing i s usabili y in specialized equipmen and signi ican ly educing manu ac u ing
cos s. SMC has ound much use in spinning elec ical machines because o i s iso opy, low
cos , and abili y o manu ac u e in ica e mesh sec ions [
37
,
38
]. E en hough he magne ism
o he powde co e is o en qui e low, i s s abili y a high equencies is qui e ema kable
(such as he MPP men ioned ea lie ). Rega ding high- equency induc o design, magne ic
co es based on SMC a e a desi able op ion. Changing he powde size, adding insula ing
ma e ials and phospho ic acid, and inc easing he p essu e du ing p epa a ion can help
Ene gies 2023,16, 4020 5 o 31
achie e an SMC co e’s desi ed o al co e pe meabili y. This helps educe he ai gap loss
and simpli ies he induc o design [39].
2.2. Wi eless Cha ging
The use o nea - ield magne ic coupling is shown in Figu e 1, by which a non-ionizing
adia i e wi eless cha ging sys em o elec ic ca s may unc ion. The u ili y side al e na ing
cu en (AC) is u ned a ound and ampli ied in a conduc i e cha ging sys em which makes
di ec cu en (DC) powe wi h a powe ac o close o 1.0. The Buck s age lowe s he DC
ol age. The cha ge ’s s a /s op can be made as “so ” as possible. I s ou pu powe can
be ine- uned inde ini ely because o he BUCK s age’s adjus able ou pu ol age, which
can be se be ween 0.03% and 0.97% o i s inpu ol age. In his case, he buck s age is no
equi ed because he “so ” s a o he cha ge can be accomplished wi h jus a p e-cha ge
ci cui consis ing o wo elay con ac s wi h one esis o , and he “so ” s op o he cha ge
may be achie ed wi h a phase-shi app oach in he in e e s age. A wi eless cha ging
sys em’s o e all cos and size can be educed by eplacing he buck s age wi h a p e-cha ge
ci cui and he phase-shi me hod.
Ene gies 2023, 16, x FOR PEER REVIEW 5 o 32
inc easing i s usabili y in specialized equipmen and signi ican ly educing manu ac u -
ing cos s. SMC has ound much use in spinning elec ical machines because o i s iso opy,
low cos , and abili y o manu ac u e in ica e mesh sec ions [37,38]. E en hough he mag-
ne ism o he powde co e is o en qui e low, i s s abili y a high equencies is qui e e-
ma kable (such as he MPP men ioned ea lie ). Rega ding high- equency induc o de-
sign, magne ic co es based on SMC a e a desi able op ion. Changing he powde size,
adding insula ing ma e ials and phospho ic acid, and inc easing he p essu e du ing
p epa a ion can help achie e an SMC co e’s desi ed o al co e pe meabili y. This helps
educe he ai gap loss and simpli ies he induc o design [39].
2.2. Wi eless Cha ging
The use o nea - ield magne ic coupling is shown in Figu e 1, by which a non-ioniz-
ing adia i e wi eless cha ging sys em o elec ic ca s may unc ion. The u ili y side al-
e na ing cu en (AC) is u ned a ound and ampli ied in a conduc i e cha ging sys em
which makes di ec cu en (DC) powe wi h a powe ac o close o 1.0. The Buck s age
lowe s he DC ol age. The cha ge ’s s a /s op can be made as “so ” as possible. I s ou -
pu powe can be ine- uned inde ini ely because o he BUCK s age’s adjus able ou pu
ol age, which can be se be ween 0.03% and 0.97% o i s inpu ol age. In his case, he
buck s age is no equi ed because he “so ” s a o he cha ge can be accomplished wi h
jus a p e-cha ge ci cui consis ing o wo elay con ac s wi h one esis o , and he “so ”
s op o he cha ge may be achie ed wi h a phase-shi app oach in he in e e s age. A
wi eless cha ging sys em’s o e all cos and size can be educed by eplacing he buck
s age wi h a p e-cha ge ci cui and he phase-shi me hod.
Du ing he in e sion s age, di ec cu en (DC) elec ici y is changed in o high- e-
quency al e na ing cu en (HFAC) so ha i can be synch onized o he swi ching e-
quency o he in e e . The p ima y compensa ion ci cui and coil e lec his high- e-
quency al e na ing cu en powe . E en wi hou a wi ed connec ion be ween he second-
a y and p ima y coils, i can s ill ecei e HFAC powe because o hei mu ual induc ance.
The seconda y compensa ion ne wo k and he seconda y coil a e uned o he same eso-
nan equency o highe efficiency le els. I is hen passed h ough a ec i ie s ep, he
HFAC powe is con e ed o DC powe , and he il e ne wo k emo es unwan ed ipple.
Now DC powe is eady o cha ge he ba e y pack. The c i ical a eas o ocus o esea ch
in o wi eless cha ging include he design o he cha ging coil, some compensa ion ne -
wo ks, powe elec onics con e e s, and con ol echniques.
Sou ce and
EMI il e
PFC boos
AC-DC
con e e
DC-AC
con e e
P ima y
compensa ion
ne wo k
Seconda y
compensa ion
ne wo k
Ba e y Fil e
ne wo k
AC-DC
Con e e
Powe Con e e Topologies
Compensa ion Ne wo k
Coil Design
Figu e 1. Wi eless cha ging sys em o EV applica ion.
The induc i e couple , which is a pa o he IPT sys em and is in cha ge o ans e -
ing ene gy om he sou ce o he ehicle, is he mos sensi i e componen o he sys em.
This esponsibili y makes i one o he sys em’s p ima y ocuses. As shown in Figu e 2, i
is p ima ily made up o wo pads, one o he ansmi e and one o he ecei e . Each
pad con ains h ee p ima y componen s: conduc ing wi es wi h a ay, magne ic co e, and
Figu e 1. Wi eless cha ging sys em o EV applica ion.
Du ing he in e sion s age, di ec cu en (DC) elec ici y is changed in o high-
equency al e na ing cu en (HFAC) so ha i can be synch onized o he swi ching
equency o he in e e . The p ima y compensa ion ci cui and coil e lec his high-
equency al e na ing cu en powe . E en wi hou a wi ed connec ion be ween he
seconda y and p ima y coils, i can s ill ecei e HFAC powe because o hei mu ual
induc ance. The seconda y compensa ion ne wo k and he seconda y coil a e uned o he
same esonan equency o highe e iciency le els. I is hen passed h ough a ec i ie
s ep, he HFAC powe is con e ed o DC powe , and he il e ne wo k emo es unwan ed
ipple. Now DC powe is eady o cha ge he ba e y pack. The c i ical a eas o ocus o
esea ch in o wi eless cha ging include he design o he cha ging coil, some compensa ion
ne wo ks, powe elec onics con e e s, and con ol echniques.
The induc i e couple , which is a pa o he IPT sys em and is in cha ge o ans e ing
ene gy om he sou ce o he ehicle, is he mos sensi i e componen o he sys em. This
esponsibili y makes i one o he sys em’s p ima y ocuses. As shown in Figu e 2, i is
p ima ily made up o wo pads, one o he ansmi e and one o he ecei e . Each
pad con ains h ee p ima y componen s: conduc ing wi es wi h a ay, magne ic co e, and
shield. The exis ing body o esea ch o e s a weal h o knowledge on co e selec ion and
coil design, which will be discussed in he pape .

Ene gies 2023,16, 4020 6 o 31
Ene gies 2023, 16, x FOR PEER REVIEW 6 o 32
shield. The exis ing body o esea ch offe s a weal h o knowledge on co e selec ion and
coil design, which will be discussed in he pape .
Wi e ay
Coil
Magne ic co e
Shield
Figu e 2. Coil a angemen .
2.3. Co e Design
The induc i e couple , which is a pa o he induc i e powe ans e (IPT) sys em
and is in cha ge o ans e ing ene gy om he sou ce o he ehicle, is he mos sensi i e
componen o he sys em. This esponsibili y makes i one o he sys em’s p ima y ocuses.
Because he in ensi y o ield lines subs an ially dec eases wi h inc easing dis ance, hese
loops ha e a es ic ed a el dis ance. Due o i s inhe en cha ac e is ics, IPT echnology
is se e ely cons ained in i s abili y o ansmi elec ici y o e conside able dis ances
(mo e han one me e ). On he o he hand, his ea u e makes he de ice sa e ega ding
he elec omagne ic ields ha may leak ou su ounding i . IPT sys ems o en use special-
ized lux concen a o s o ocus he luxes c ea ed om he ansmi e owa ds he e-
cei e [40]. These lux concen a o s aid in imp o ing i s pe o mance as well as he effi-
ciency o he sys em. I dec eases he amoun o lux ha leaks ou a ound he sys em. Fo
he sys em o mee he s anda d sa e y limi a ions, s aigh o wa d shielding is equi ed,
which will educe he leakage lux. Addi ionally, he nega i e effec ha he shield will
ha e on he pe o mance o he sys em will be negligible [41]. The esea ch abou he co e
design, such as he ma e ial, shape, and measu emen s discussed in his pa , can be ound
ac oss he ele an published wo ks.
2.3.1. Ai Co e
As a esul , he IPT sys em, in his ins ance, is in ended o ope a e wi hou any lux
concen a o . Figu e 3 shows lux passing h ough he ai . This echnique will make he
IPT sys em less expensi e, ha e a lowe o e all weigh , and be easie o design and in e-
g a e. In addi ion o his, i emo es he losses ha come wi h a magne ic co e. Howe e ,
conside ing ai -co e coils necessi a es he u iliza ion o addi ional u ns wi hin he sys em,
inc easing bo h cos and winding loss [42].
Addi ionally, due o signi ican in luence, he ai -co e coil can ealize a mo e skin
effec and he p oximi y effec he same as EMF ields [43–45]. The massi e amoun o
winding loss incu ed in he ai -co e coil is mo e signi ican han hose o solenoids due
o excessi e winding losses o educing he co e losses. Due o his limi a ion, ai -co e
coils a e no ecommended in la ge powe IPT sys ems [43,46,47].
Figu e 2. Coil a angemen .
2.3. Co e Design
The induc i e couple , which is a pa o he induc i e powe ans e (IPT) sys em
and is in cha ge o ans e ing ene gy om he sou ce o he ehicle, is he mos sensi i e
componen o he sys em. This esponsibili y makes i one o he sys em’s p ima y ocuses.
Because he in ensi y o ield lines subs an ially dec eases wi h inc easing dis ance, hese
loops ha e a es ic ed a el dis ance. Due o i s inhe en cha ac e is ics, IPT echnology is
se e ely cons ained in i s abili y o ansmi elec ici y o e conside able dis ances (mo e
han one me e ). On he o he hand, his ea u e makes he de ice sa e ega ding he
elec omagne ic ields ha may leak ou su ounding i . IPT sys ems o en use specialized
lux concen a o s o ocus he luxes c ea ed om he ansmi e owa ds he ecei e [
40
].
These lux concen a o s aid in imp o ing i s pe o mance as well as he e iciency o he
sys em. I dec eases he amoun o lux ha leaks ou a ound he sys em. Fo he sys em
o mee he s anda d sa e y limi a ions, s aigh o wa d shielding is equi ed, which will
educe he leakage lux. Addi ionally, he nega i e e ec ha he shield will ha e on he
pe o mance o he sys em will be negligible [
41
]. The esea ch abou he co e design, such
as he ma e ial, shape, and measu emen s discussed in his pa , can be ound ac oss he
ele an published wo ks.
2.3.1. Ai Co e
As a esul , he IPT sys em, in his ins ance, is in ended o ope a e wi hou any lux
concen a o . Figu e 3shows lux passing h ough he ai . This echnique will make he IPT
sys em less expensi e, ha e a lowe o e all weigh , and be easie o design and in eg a e. In
addi ion o his, i emo es he losses ha come wi h a magne ic co e. Howe e , conside ing
ai -co e coils necessi a es he u iliza ion o addi ional u ns wi hin he sys em, inc easing
bo h cos and winding loss [42].
Addi ionally, due o signi ican in luence, he ai -co e coil can ealize a mo e skin e ec
and he p oximi y e ec he same as EMF ields [
43
–
45
]. The massi e amoun o winding
loss incu ed in he ai -co e coil is mo e signi ican han hose o solenoids due o excessi e
winding losses o educing he co e losses. Due o his limi a ion, ai -co e coils a e no
ecommended in la ge powe IPT sys ems [43,46,47].
Ene gies 2023,16, 4020 7 o 31
Ene gies 2023, 16, x FOR PEER REVIEW 7 o 32
Figu e 3. Ai -co ed coil.
2.3.2. Fe i e Co e
IPT sys ems ha cha ge elec ic ehicles mos equen ly use a e i e co e. Fe i e is
a ce amic ma e ial p oduced by combining signi ican po ions o FeO3 wi h insigni ican
po ions o mo e han one me al, such as nickel, zinc, and ba ium, and hen hea ing he
esul ing mix u e [47]. Fe i e is a nonconduc i e ype o e omagne ic subs ance (an in-
sula o ) and can be easily magne ized and a ac ed by a magne [48]. Ha d e i e and
so e i e a e dis inc ypes ha can be dis inguished om one ano he acco ding o hei
esis ance o demagne iza ion. The i s ype is amous o making pe manen magne s o
lowe -powe mo o s because o i s coe ci e solid and low demagne izing abili y [49]. As
a esul , he so e i e n’s low coe ci ely may be magne ized and demagne ized wi h
ela i e ease, and i also ac s as a conduc o o elec ic lux [50]. In manu ac u ing, so
e i e is u ilized o c ea e magne ic e i e co es ha a e efficien o HF induc o s and
ans o me s [51]. Mn Zn and Ni Zn a e he so e i es u ilized mos equen ly in IPT
sys ems due o he ela i ely modes losses hey expe ience a high equencies [52]. They
ha e a high magne ic pe meabili y and a low elec ical conduc i i y, educing eddy cu -
en s.
A e omagne ic co e is usually added o he ansmi ing and ecei ing coil. Mo e
s udies in es iga ed how e i e affec s he mu ual induc ance o he sys em, powe ans-
e capaci y, and efficiency [53,54]. The e i es a he p ima y coil we e swi ched ou o a
second pa asi ic coil posi ioned benea h he p ima y coil o enhance he shielding pe o -
mance while sligh ly lowe ing he ansmission efficiency. This e og ession elies on he
space sepa a ing he pa asi ic coil and he p ima y ansmi e om ano he o al numbe
o pa asi ic coils. The effec i eness ises in di ec p opo ion o he squa e o he dis ance
ha sepa a es hese wo coils [55].
In mos cases, he e i e ma e ial’s co e comp ises indi idual e i e blocks assem-
bled in a speci ic pa e n o p oduce he co e. These blocks can be shaped simila o an I
[46,56], a ec angle [57,58], o a squa e [53,57,59]. The pad’s s uc u e will dic a e, o some
ex en , he o m ha he e en ual co e will ake ( ec angula , ci cula , D-D, double-DQ,
and QDQ). Howe e , depending on he cons uc ion o he pad, he shape o he e i e
co e can be one o h ee diffe en hings: a single pla [53–55,60,61], many ba s [46,57,61–
63], o disc e e iles [64,65]. Table 1 lays ou hese h ee dis inc possibili ies o conside -
a ion. The au ho s o [66,67] ecommended u ilizing wo e i e laye s s acked on each
o he . They also examined how he coupling ac o s would affec he sys em’s pe o -
mance when bo h induc ances we e inco po a ed. P ope ly adding e i e componen s in
an IPT may be c ucial o aligning he lux lines, lowe ing he amoun o leakage lux,
imp o ing coupling and pe o mance, and making he sys em con o m o he speci ied
Figu e 3. Ai -co ed coil.
2.3.2. Fe i e Co e
IPT sys ems ha cha ge elec ic ehicles mos equen ly use a e i e co e. Fe i e is a
ce amic ma e ial p oduced by combining signi ican po ions o FeO
3
wi h insigni ican
po ions o mo e han one me al, such as nickel, zinc, and ba ium, and hen hea ing he
esul ing mix u e [
47
]. Fe i e is a nonconduc i e ype o e omagne ic subs ance (an
insula o ) and can be easily magne ized and a ac ed by a magne [
48
]. Ha d e i e and
so e i e a e dis inc ypes ha can be dis inguished om one ano he acco ding o hei
esis ance o demagne iza ion. The i s ype is amous o making pe manen magne s
o lowe -powe mo o s because o i s coe ci e solid and low demagne izing abili y [
49
].
As a esul , he so e i e n’s low coe ci ely may be magne ized and demagne ized wi h
ela i e ease, and i also ac s as a conduc o o elec ic lux [
50
]. In manu ac u ing, so
e i e is u ilized o c ea e magne ic e i e co es ha a e e icien o HF induc o s and
ans o me s [
51
]. Mn Zn and Ni Zn a e he so e i es u ilized mos equen ly in IPT sys-
ems due o he ela i ely modes losses hey expe ience a high equencies [
52
]. They ha e
a high magne ic pe meabili y and a low elec ical conduc i i y, educing eddy cu en s.
A e omagne ic co e is usually added o he ansmi ing and ecei ing coil. Mo e
s udies in es iga ed how e i e a ec s he mu ual induc ance o he sys em, powe ans e
capaci y, and e iciency [
53
,
54
]. The e i es a he p ima y coil we e swi ched ou o a
second pa asi ic coil posi ioned benea h he p ima y coil o enhance he shielding pe o -
mance while sligh ly lowe ing he ansmission e iciency. This e og ession elies on he
space sepa a ing he pa asi ic coil and he p ima y ansmi e om ano he o al numbe
o pa asi ic coils. The e ec i eness ises in di ec p opo ion o he squa e o he dis ance
ha sepa a es hese wo coils [55].
In mos cases, he e i e ma e ial’s co e comp ises indi idual e i e blocks assembled
in a speci ic pa e n o p oduce he co e. These blocks can be shaped simila o an I [
46
,
56
],
a ec angle [
57
,
58
], o a squa e [
53
,
57
,
59
]. The pad’s s uc u e will dic a e, o some ex en ,
he o m ha he e en ual co e will ake ( ec angula , ci cula , D-D, double-DQ, and QDQ).
Howe e , depending on he cons uc ion o he pad, he shape o he e i e co e can
be one o h ee di e en hings: a single pla [
53
–
55
,
60
,
61
], many ba s [
46
,
57
,
61
–
63
], o
disc e e iles [
64
,
65
]. Table 1lays ou hese h ee dis inc possibili ies o conside a ion.
The au ho s o [
66
,
67
] ecommended u ilizing wo e i e laye s s acked on each o he .
They also examined how he coupling ac o s would a ec he sys em’s pe o mance when
bo h induc ances we e inco po a ed. P ope ly adding e i e componen s in an IPT may
be c ucial o aligning he lux lines, lowe ing he amoun o leakage lux, imp o ing
coupling and pe o mance, and making he sys em con o m o he speci ied ange o
elec omagne ic ields [
57
]. Howe e , using e i e aises p ices, making hings hea ie and
mo e likely o b eak. Fe i e is also mo e challenging o clean.
Ene gies 2023,16, 4020 8 o 31
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
Ene gies 2023, 16, x FOR PEER REVIEW 8 o 32
ange o elec omagne ic ields [57]. Howe e , using e i e aises p ices, making hings
hea ie and mo e likely o b eak. Fe i e is also mo e challenging o clean.
Table 1. Types o e i e co es.
Pla e Co e Ba Co e Ti le Co e
Cu en
Fe i e shee
Aluminium shield
Fe i e co e
Aluminium shield
DD Coil
Fe i e iles
Aluminium shield
Coil
Fe i e pla e
Coil
Fe i e co e DDQ Coil
Quad a u e coil
Coil
Fe i e
Fe i e co e
Aluminium shield
Bipola pad
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad and
au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei high
densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all ene gy
consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s he
powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al s ud-
ies looked in o po en ial eplacemen s o e i es ha we e mo e effec i e. A ma e ial con-
sis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [68–70]. These
nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic p op-
e ies and wi hs and mechanical shocks. In [71], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an effec on he effi-
ciency and imp o ed shielding pe o mance [72]. Howe e , hey a e exceedingly delica e
2.3.3. Nanopa icle Co e
E en hough e i e co es exhibi excellen pe o mance in IPT sys ems, he p esence
o hese co es does cause some limi s. Due o he displacemen and p essu es he oad
and au omobiles c ea e, e i es a e b i le and easily b oken. Addi ionally, due o hei
high densi y, e i es con ibu e o an inc ease in bo h he ehicle’s mass and i s o e all
ene gy consump ion. Gene ally, e i e ma e ials ha e a low sa u a ion le el which es ic s
he powe ans e abili y, pa icula ly in high powe ci cums ances. As a esul , se e al
s udies looked in o po en ial eplacemen s o e i es ha we e mo e e ec i e. A ma e ial
consis ing o e omagne ic nanopa icles is sugges ed o use in he IPT sys em [
68
–
70
].
These nanopa icles can be combined wi h a polyme pa icle o s eng hen hei magne ic
p ope ies and wi hs and mechanical shocks. In [
71
], an addi ional nanocomposi e hin ilm
o he IPT sys em was p oposed. This ilm demons a es inc eased magne ic pe meabili y
in compa ison o e i e. Including pa icles can dec ease he sys em’s weigh , boos powe
ans e , and imp o e he shield pe o mance while ha ing less o an e ec on he e iciency
and imp o ed shielding pe o mance [
72
]. Howe e , hey a e exceedingly delica e and
expensi e, con ibu ing o he IPT sys em’s o e all weakness and making i easy o b eak.
Ene gies 2023,16, 4020 9 o 31
2.3.4. Flexible Magne ic Ma e ial Co e
The e was some discussion in [
73
,
74
] abou u ilizing mo able magne ic co es o
he IPT sys em. The elec odeposi ion me hod, dis inguished by i s simple applica ion,
low cos , and p ecise pa e n con ol, can make his ma e ial ela i ely simple. NiFe so
magne ic ma e ial, which showed inc eased pe meabili y and less esis ance han o he
pe manen magne s, including FeH N and CoNbZ , was ecommended as a ma e ial o
a lexible co e [
75
]. Because o hese quali ies, he e is a educ ion in co e losses and an
imp o emen in quali y ac o s. A pa ylene subs a e has been added o he compound o
make he NiFe mo e lexible and imp o e i s biocompa ibili y. The lexible co e’s esis ance
o physical loading and dis u bance inc eases he sys em’s esilience.
2.3.5. Conc e e Magne ic Co e
Employing lexible co es, magne ic nanopa icles, and e i e in he ehicle pad is
mo e con enien han using o he co es. Howe e , he ansmi e pad canno be pu
o bu ied in he oad because none o he ma e ials is sui able. The ansmi e pad is
suscep ible o ha m om any c acks in he oad. As a esul , in [
76
], a magne izable
conc e e was p oduced and p oposed o be used in he ansmi e . This conc e e is
a composi e ma e ial ha can be cemen ed wi h magne ic pa icles in a ying mixed
p opo ions. The olume ic a ios o he wo componen s can a y. Magne ic conc e e is
lexible and possesses excellen mechanical capabili ies [
77
]. I is also compa ible wi h he
oad. Because he magne ic pa icles a e eusable, he cos is negligible. The esea ch was
conduc ed o unde s and be e how magne izable conc e e compa es o e i es in e ms
o i s pe meabili y and mechanical p ope ies [
77
]. In [
78
,
79
], he e ec i eness o an IPT
sys em aking magne izable conc e e in o accoun was s udied and compa ed o ha o a
e i e-based sys em.
In ligh o his explana ion, Table 2compa es he a ious so magne ic ma e ials
ha could be used in an IPT sys em. Resea che s and manu ac u e s may bene i om
compa ing all ma e ials ega ding magne ic lux densi y (B), magne ic ield densi y (H),
ela i e pe meabili y (µ ), and c i ical empe a u e (Tc).
Table 2. Magne ic ma e ials p ope ies o so magne ic ma e ial.
Types o Ma e ial Ma e ial H (A/m) B (T) Tc(◦C) µ
Fe i e PC95 9.5 0.54 215 3300
Fe i e PC90 13 0.54 250 2200
Fe i e PC40 15 0.5 200 2300
Amo phous 2714A 0.2 0.57 225 170,000
Amo phous 2605SAI 3.2 3.2 392 45,000
Nanoc ys alline FeCuNbSiB 0.53 1.24 843 157,000
3. Elec omagne ic Field Shielding
Induc i e powe ans e is used in EV cha ge s o ans e a conside able amoun o
powe (up o se e al hund ed kilowa s) ac oss a long dis ance. The esul is ha when
cha ging, signi ican EMFs a e o en p oduced in he icini y o he sys em. In e na ional
no ms and guidelines [
80
,
81
] indica e ha hese ields may exceed accep able le els. Shield-
ing agains EMFs is commonly employed in IPT sys ems o educing he lux leakage o
he o e all sys em, enhancing he coupling in e p e a ion, and aising quali y and e iciency
ac o s [
82
,
83
]. Se e al p o ec i e shielding is documen ed in he li e a u e, including
ac i e, passi e, and conduc i e [84–87].
3.1. Passi e Shielding
Using a passi e componen (ei he magne ic o a conduc o ) ha assis s in blocking
and/o shaping elec omagne ic ield (EMF) o he educ ion in lux leakage in a sys em.
Ene gies 2023,16, 4020 16 o 31
Table 6. Compa ison be ween di e en h ee coil s uc u es and induc i e pads.
S uc u e D-DQ Poly-Phase Shape T i-Pola Shape
Shape
Ene gies 2023, 16, x FOR PEER REVIEW 16 o 32
Table 6. Compa ison be ween diffe en h ee coil s uc u es and induc i e pads.
S uc u e D-DQ Poly-Phase Shape T i-Pola Shape
Shape
Fe i e co e DDQ Coil
Quad a u e coil
Coil 1
Coil 2
Coil 3
O e lap
be ween coils
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Poo
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mode a e Mo e
Pola iza ion Pola ised Pola ised Pola ised
Cohesi eness High Mode a e High
Applica ion Recep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Ex emely less Less Less
E iciency (%) - 85 91
Re . [93,115,116] [120–122] [107,123,124]
Ene gies 2023, 16, x FOR PEER REVIEW 16 o 32
Table 6. Compa ison be ween diffe en h ee coil s uc u es and induc i e pads.
S uc u e D-DQ Poly-Phase Shape T i-Pola Shape
Shape
Fe i e co e DDQ Coil
Quad a u e coil
Coil 1
Coil 2
Coil 3
O e lap
be ween coils
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Poo
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mode a e Mo e
Pola iza ion Pola ised Pola ised Pola ised
Cohesi eness High Mode a e High
Applica ion Recep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Ex emely less Less Less
E iciency (%) - 85 91
Re . [93,115,116] [120–122] [107,123,124]
Ene gies 2023, 16, x FOR PEER REVIEW 16 o 32
Table 6. Compa ison be ween diffe en h ee coil s uc u es and induc i e pads.
S uc u e D-DQ Poly-Phase Shape T i-Pola Shape
Shape
Fe i e co e DDQ Coil
Quad a u e coil
Coil 1
Coil 2
Coil 3
O e lap
be ween coils
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Poo
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mode a e Mo e
Pola iza ion Pola ised Pola ised Pola ised
Cohesi eness High Mode a e High
Applica ion Recep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Ex emely less Less Less
E iciency (%) - 85 91
Re . [93,115,116] [120–122] [107,123,124]
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Poo
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mode a e Mo e
Pola iza ion Pola ised Pola ised Pola ised
Cohesi eness High Mode a e High
Applica ion Recep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Ex emely less Less Less
E iciency (%) - 85 91
Re . [93,115,116] [120–122] [107,123,124]

Ene gies 2023,16, 4020 17 o 31
Table 7. Compa ison be ween di e en mul i-coil s uc u es and induc i e pads: G oup 1.
S uc u e Quad uple Quad DDDQ Th ee Phase Dual Laye
Shape
Ene gies 2023, 16, x FOR PEER REVIEW 17 o 32
Table 7. Compa ison be ween diffe en mul i-coil s uc u es and induc i e pads: G oup 1.
S uc u e Quad uple Quad DDDQ Th ee Phase Dual Laye
Shape
Coil
Fe i e
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Mode a e
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mo e Mode a e
Pola iza ion Pola ised Pola ised -
Cohesi eness High High -
Applica ion T ansmission and ecep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Less Less Less
E iciency (%) - 97 91
Re . [120,125–127] [128–130] [131]
Ene gies 2023, 16, x FOR PEER REVIEW 17 o 32
Table 7. Compa ison be ween diffe en mul i-coil s uc u es and induc i e pads: G oup 1.
S uc u e Quad uple Quad DDDQ Th ee Phase Dual Laye
Shape
Coil
Fe i e
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Mode a e
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mo e Mode a e
Pola iza ion Pola ised Pola ised -
Cohesi eness High High -
Applica ion T ansmission and ecep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Less Less Less
E iciency (%) - 97 91
Re . [120,125–127] [128–130] [131]
Ene gies 2023, 16, x FOR PEER REVIEW 17 o 32
Table 7. Compa ison be ween diffe en mul i-coil s uc u es and induc i e pads: G oup 1.
S uc u e Quad uple Quad DDDQ Th ee Phase Dual Laye
Shape
Coil
Fe i e
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Mode a e
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mo e Mode a e
Pola iza ion Pola ised Pola ised -
Cohesi eness High High -
Applica ion T ansmission and ecep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Less Less Less
E iciency (%) - 97 91
Re . [120,125–127] [128–130] [131]
Ai gap - 200 mm 210 mm
In e ac ion o lux Two ended Two ended One ended
P o ec ion le el S ong Mode a e Mode a e
Cha ging A ea Mo e Mo e Mo e
Requi ed Space Mo e Mo e Mode a e
Pola iza ion Pola ised Pola ised -
Cohesi eness High High -
Applica ion T ansmission and ecep ion T ansmission and ecep ion T ansmission and ecep ion
Leakage index Less Less Less
E iciency (%) - 97 91
Re . [120,125–127] [128–130] [131]
Ene gies 2023,16, 4020 18 o 31
Table 8. Compa ison be ween di e en mul i-coil s uc u es and induc i e pads: G oup 2.
S uc u e Dual T ansmi e and Recei e Dual T ansmi e Dual Recei e Mul i T ansmi e
Shape
Ene gies 2023, 16, x FOR PEER REVIEW 18 o 32
Table 8. Compa ison be ween diffe en mul i-coil s uc u es and induc i e pads: G oup 2.
S uc u e Dual T ansmi e and Recei e Dual T ansmi e Dual Recei e Mul i T ansmi e
Shape
T ansmi e
Recei e
T ansmi e
Recei e
Lead coil
Sou ce coil
In e media e
coil 1
In e media e
coil 2
Ai gap 200 mm 210 mm -
In e ac ion o lux One ended Two ended One ended
P o ec ion le el Poo Poo Mode a e
A ea o cha ging Mode a e Mo e Mo e
Dis ance Less Mode a e Mo e
Pola iza ion Non Pola ised Non Pola ised Non Pola ised
Cohesi eness Mode a e High High
Applica ion T ansmission T ansmission and ecep ion T ansmission
Le el o leakage Less Less Mode a e
E iciency (%) 96% 91% -
Re . [132–134] [135–137] [138–140]
Ene gies 2023, 16, x FOR PEER REVIEW 18 o 32
Table 8. Compa ison be ween diffe en mul i-coil s uc u es and induc i e pads: G oup 2.
S uc u e Dual T ansmi e and Recei e Dual T ansmi e Dual Recei e Mul i T ansmi e
Shape
T ansmi e
Recei e
T ansmi e
Recei e
Lead coil
Sou ce coil
In e media e
coil 1
In e media e
coil 2
Ai gap 200 mm 210 mm -
In e ac ion o lux One ended Two ended One ended
P o ec ion le el Poo Poo Mode a e
A ea o cha ging Mode a e Mo e Mo e
Dis ance Less Mode a e Mo e
Pola iza ion Non Pola ised Non Pola ised Non Pola ised
Cohesi eness Mode a e High High
Applica ion T ansmission T ansmission and ecep ion T ansmission
Le el o leakage Less Less Mode a e
E iciency (%) 96% 91% -
Re . [132–134] [135–137] [138–140]
Ene gies 2023, 16, x FOR PEER REVIEW 18 o 32
Table 8. Compa ison be ween diffe en mul i-coil s uc u es and induc i e pads: G oup 2.
S uc u e Dual T ansmi e and Recei e Dual T ansmi e Dual Recei e Mul i T ansmi e
Shape
T ansmi e
Recei e
T ansmi e
Recei e
Lead coil
Sou ce coil
In e media e
coil 1
In e media e
coil 2
Ai gap 200 mm 210 mm -
In e ac ion o lux One ended Two ended One ended
P o ec ion le el Poo Poo Mode a e
A ea o cha ging Mode a e Mo e Mo e
Dis ance Less Mode a e Mo e
Pola iza ion Non Pola ised Non Pola ised Non Pola ised
Cohesi eness Mode a e High High
Applica ion T ansmission T ansmission and ecep ion T ansmission
Le el o leakage Less Less Mode a e
E iciency (%) 96% 91% -
Re . [132–134] [135–137] [138–140]
Ai gap 200 mm 210 mm -
In e ac ion o lux One ended Two ended One ended
P o ec ion le el Poo Poo Mode a e
A ea o cha ging Mode a e Mo e Mo e
Dis ance Less Mode a e Mo e
Pola iza ion Non Pola ised Non Pola ised Non Pola ised
Cohesi eness Mode a e High High
Applica ion T ansmission T ansmission and ecep ion T ansmission
Le el o leakage Less Less Mode a e
E iciency (%) 96% 91% -
Re . [132–134] [135–137] [138–140]
Ene gies 2023,16, 4020 19 o 31
As he coupling ac o k educes and g ound clea ance inc eases, he e ical sepa a ion
be ween he GA and VA coils becomes inc easingly signi ican . The e o e, o classi y he
WPT sys ems acco ding o he an icipa ed maximum g ound clea ance, h ee Z-classes ha e
been de ined as 100–150 mm, 140–210 mm, and 170–250 mm. In addi ion, he o se posi ion
is s anda dised conce ning he op imal posi ion, which co esponds wi h he cen es o
ound GA and VA coils whene e hey a e aligned. This op imal posi ion was de e mined
by compa ing he o se and op imal posi ions. Once he coils ha e been in hei ideal
posi ion, he WPT sys em can unc ion a i s highes e iciency le el. In he la e al di ec ion,
he maximum pe missible o se is ±100 mm, and he o e and a di ec ion is ±75 mm.
In p ac ice, he g ounding coil will be ins alled on he loo as well as he VA coil will
be ins alled in he unde ca iage o he ehicle; howe e , his con igu a ion is no se in
s one and is subjec o change based on he WPT le el o he EV imposing sys em, he
clea ance om he g ound ha a ies depending on he ype o ehicle and he ehicle’s
weigh , and he o se place due o a ague pa king job. Any de ia ion om he ideal
posi ion causes a educ ion in he coupling ac o k, which in u n causes an inc ease in he
emission o magne ic ields. O he pa ame e s ha ha e a c ucial e ec on he dispe sion o
he magne ic ield include he dimensions and shape o he EV bodyshell and he ma e ial
i is made o . The zone beside he ca , jus a ew ee om he g ound, is he mos c i ical
loca ion o EMF sa e y (excep he en i e space below he ehicle, secu ed by a secu i y
sys em). This is because he en i e a ea below he ehicle is p o ec ed. Fo each WPT class,
he ield’s magne ic s eng h is mos signi ican o mos minia u e ehicles wi h he g ea es
possible g ound clea ance and o se .
5. Wi eless Cha ging Sys em Sus ainabili y and Social Impac s
The WPT is bene icial o wi elessly cha ging elec ic ehicles (EVs). The wo ld’s mos
signi ican pollu ion sou ce oday comes om au omobiles powe ed by gasoline and diesel
engines as well as la ge machine y ha uns on diesel uel. The ollowing pa will cla i y
any p econcep ions ega ding speci ic heal h, economic, and en i onmen al conce ns.
5.1. Ene gy and En i onmen al Reckoning
Wi eless EV cha ging p ese es he en i onmen in wo s ages. Le us ake in o accoun
all o he sys ems ha a e capable o being d i en by elec ic powe . The u ilisa ion o
elec ical powe a he han gasoline o diesel engines is he p e e ed op ion. The mos
signi ican ad an age hey o e is ha elec ical equipmen does no di ec ly pollu e he
en i onmen . None heless, he e is an issue wi h he capaci y o elec ical equipmen o
s o e elec ici y. Hence, WPT will ope a e ha equipmen wi elessly, o i he ba e y is used
o d i ing he machine, i will u ilise WPT, which can be eadily cha ged since ba e ies
a e used o d i ing he machine. WPT dec eases he ba e y’s load by wi elessly ope a ing
he de ice, educing he sys em’s o e all weigh . B own in es iga ed he plug-in and
wi elessly powe ed sys ems a he Uni e si y o Michigan [
141
] using a 12-yea amewo k
analysis o make compa abili y. Two conclusions eme ged.
1.
WPT sys ems educe he need o ba e ies, which can compensa e o he GHG
emissions and ex a ene gy he wi eless cha ging in as uc u e needs.
2.
Reducing he size and weigh o he ba e y will co e he ex a cos s o ins alling a
wi eless sys em.
The e is a signi ican gap in he ange o powe ansmission be ween plug-in cha ging,
also known as powe ans e , and when compa ing he echnological de elopmen o
hese wo cha ging me hods. Ye , i is e iden ha WPT is a mo e p ac ical, secu e, and
en i onmen ally iendly in con as . Resea che s ha e claimed ha in he u u e, powe
ansmission up o me es will make sus ainable mobili y be e by cu ing down on he
use o cables and ba e ies.
Ene gies 2023,16, 4020 20 o 31
5.2. Economic and Policy Analysis
The cha ging in as uc u e, he ba e y, and he phase ene gy cos [
142
] a e he h ee
p ima y componen s o WPT echnology’s p oduc li e cycle ha compe e wi h hose o
o he echnologies. Compa ed o he cos o a wi ed elec ic ehicle cha ge , he wi eless
cha ging sys em only equi es wo magne ic couple s, he only addi ional componen
u ilised in he sys em. This will lead o an addi ional ma e ial cos o a ound $400 US
dolla s o he 8-kW cha ge [
143
]. Because he cha ge has such a long li e, his p ice is
easonable due o i s added con enience. Compa ed o diesel buses, wi eless buses can
expe ience a educ ion in uel cos s o app oxima ely US $90,000, o up o 80%, h oughou
he ehicle’s li e ime [
144
]. Compa ing he cos o main aining a wi eless cha ging sys em
wi h ha o a wi ed sys em shows ha he wi eless sys em’s main enance cos s a e lowe .
This is because he e is no physical con ac be ween he ansmi e and he ecei e . The
ba e y is he p ima y conce n ega ding he cos o he wi eless cha ging sys em. The
equi ed onboa d ba e y powe will dec ease i he e a e su icien cha ging s a ions and
ice e sa. The cos unc ions o wi eless cha ging come in wo di e en o ms. The i s is
he cos unc ion o he ba e y, and he second is he ansmi e ’s cos unc ion. Two cos s
a e associa ed wi h he powe ansmi e unc ion: (1) The cos o he ansmi e a ies
based on i s leng h (2). The cos o he in e e and he labou p ice o connec o he g id
makes up he ixed cos .
5.3. Heal h and Sa e y
When i comes o he ex ensi e use o elec ic ehicle wi eless cha ging, he i s issue
ha needs o be answe ed is “is i sa e o heal h?”. This is p ima ily because people
a e conce ned abou he elec omagne ic ield ha is c ea ed when wi eless powe is
ansmi ed. E ic Gile [
145
] s a es ha WPT is a signi ican ly sa e al e na i e o he
adia ion emi ed by cell phones. When Moon e al. adop ed [
146
] a double shielding
coil and ou capaci o s o minimise he amoun o was ed magne ic lux, hey p oposed
using a phase shi e o shielding. This double-shielding coil gene a es an opposing
ield, which e ec i ely nulli ies he e ec o he leakage lux. The IEEE and ICNIRP
ha e imposed limi s on he in ensi y, equency, and o he aspec s o elec omagne ic
adia ions and ields employed in wi eless applica ions. The main objec i e o his s anda d
is o es ablish exposu e limi s ha will p o ec people om he known ha m ul e ec s o
elec omagne ic wa es on human heal h when exposed o adio equency elec ic, magne ic,
and elec omagne ic ields in he equency ange [
147
] o 3 kHz–300 GHz. These ields
can induce hese e ec s. Resea che s a e wo king o de elop a ba ie ha can p o ec
agains elec omagne ic ields. Excessi e exposu e o elec omagne ic adia ion can cause a
a ie y o heal h ailmen s. The ch onic exposu e e e ence le el is de e mined based on he
condi ions o maximum coupling o he ield o he indi idual exposed o i . This calcula ion
conside s he cen al ne ous sys em in luence and he pe iphe al ne ous sys em e ec .
Be ween 25 Hz and 10 MHz cons i u es he basic e e ence le el o occupa ional exposu e
o elec ic ields.
Va ious elec ical, chemical, and he mal dange s, as well as dange s posed by compo-
nen s o an EV ha ha e been damaged, a e included among he haza ds posed by EVs.
Using a haza d a ing as a amewo k, an assessmen o he dange s o elec ic ehicles is
ca ied ou . The ba e y, he wi ing, he b akes, and o he componen s a e he mos ypical
causes o acciden s. These po en ial dange s could esul in a wide a ie y o inciden s,
including i es and explosions, as well as mishaps on he oad and many mo e. Because
o he inhe en dange s o elec ic ehicles, i is c ucial o ake a cu so y look a each o
hese aspec s o ensu e ha EVs can unc ion e ec i ely while inco po a ing any necessa y
upg ades [148].
The li hium-ion ba e y, an essen ial pa o an elec ic ehicle, is also he sou ce o
he mos common isk associa ed wi h hese ehicles. The excep ional pe o mance o
li hium-ion ba e ies has led o hei widesp ead use in elec ic ehicles (EVs); ye , con inual
i es and explosions ha e limi ed he applica ions o which hey may be employed. The
Ene gies 2023,16, 4020 21 o 31
scope o imp o emen ha can be made in li hium-ion is p ima ily connec ed o cell
sa e y, which co e s cell chemis y, cooling and balancing, and some o he exis ing sa e y
egula ions. I is possible ha he undamen al quali ies o li hium-ion ba e ies, such as
hei high speci ic capaci y and ol age, lack o memo y, low le el o sel -discha ge, and
b oad empe a u e ange o ope a ion, could make li hium-ion ba e ies less sa e han o he
ypes o echa geable ba e ies [
149
]. The uns able elec oly ic sys em is mos ly o blame
o he ailu e o he li hium-ion ba e y. Vol age and empe a u e a e he wo ac o s ha
in luence he many p ocesses inside a ba e y. The cons an p oduc ion o hea and gas
causes wea and ea on he ba e y and he igni ing o combus ible i ems. The ba e y’s
pe o mance migh be impac ed by he su ounding en i onmen as well. Many di e en
kinds o esea ch ha e been conduc ed, and he wo k ha has been ca ied ou has been
eleased co e ing he sa e y o ba e y- ela ed p oblems such as elec oly es, he ma e ials
o ca hode and anode, imp o ed ba e ies, and ba e y he mal unaway di icul ies as
well as o he ela ed opics [
150
]. Al e ing he cell’s in e nal chemis y, enhancing a cell’s
cooling mechanism, and ebalancing he cells a e some o he o he po en ial me hods ha
ha e been sugges ed o enhancing he ba e y’s sa e y unde any gi en ci cums ance.
When an acciden happens in ol ing an elec ic ehicle (EV), i is a oo isky and
unsa e o ouch he EV since i has high- ol age in eg a ed componen s. This is he p ima y
eason o he elec ical isks in EVs. An elec ic ehicle’s ol ages a e a highe han a
ypical p o ec ion ol age. The e o e, when de eloping an elec ic ehicle, conside able
hough should be gi en o he elec ical dange s, as he ehicle mus be secu e om elec-
ical haza ds. Va ious echnical sa egua ds, such as he high- ol age in e lock mechanism
and he insula ion acking o he ene gy s o age sys em, can ensu e an elec ic ehicle’s
p o ec ion om unan icipa ed dange s. All high- ol age elec ical componen s ha e been
buil so ha he isk o inju y ha can be induced by ouching hem can be elimina ed.
These componen s a e gal anically insula ed om he low- ol age sys em and he es o
he ehicle’s body.
Chemical isks a e he mos common kind o haza ds ha can be gene a ed by an
elec ic ehicle, and hey a e caused when hyd oca bon and hyd ogen luo ides a e eleased
in o he a mosphe e. When hese compounds come in o ouch wi h a human being ia
inhaling, hey unleash hei po en ially le hal e ec s. I he sys em does no ha e a p ope
en ing mechanism, he hyd oca bons ha discha ge om he cell can po en ially ca ch
i e, which migh lead o a la ge explosion. In a simila ein, hyd ogen luo ides, which a e
p oduced when a ba e y ca ches i e, a e a po en ial haza d.
When he empe a u e is conside ed, he po en ial o he mal isks in an elec ic
ehicle becomes appa en . Some chemical p ocesses may occu wi hin a li hium-ion
ba e y cell i he cells a e subjec ed o empe a u es signi ican ly highe han hei no mal
wo king empe a u e ange, which does no o en go o e six y deg ees Celsius. Because
hese eac ions a e exo he mic, he cell loses a signi ican quan i y o hea , which migh
lead o he mal dange s i he cell is no adequa ely p o ec ed. I one o he ba e y’s
cells expe iences he mal unaway, he high empe a u e p oduced by ha cell will cause
damage o any adjacen cells ha i is in con ac wi h. Because i in ol es an exo he mic
eac ion du ing he decomposi ion p ocess, his p ocess, which is b ough on because o
he he mal unaway in an EV, is di icul o s op [148].
The issue o an EV’s ela i ely low le el o backg ound noise is he one ha p esen s
he mos signi ican p e alence o isk. The low noise p oduced by an elec ic ehicle has
wo sides: an ad an age and a loss ha a ises. The ad an age o low noise is essen ial
since i is ela ed o he en i onmen and helps minimise he noise pollu ion c ea ed due
o undesi ed noises om au omobiles. On he o he hand, he e is a possibili y o pu ing
one’s li e in dange when d i ing an elec ic ehicle on public highways because o he
ela i ely quie ehicle ope a ion a mode a e speeds. When pedes ians y o c oss he
s ee in me opoli an a eas, hey equen ly ind hemsel es in p eca ious si ua ions since
i can be di icul o hem o pick up on he sound coming om EVs. As a esul , hey un
he isk o being wounded. When a elling a low speeds in an EV, he engine ails o

Ene gies 2023,16, 4020 22 o 31
p oduce any sound; as a esul , i is di icul o iden i y he ca . The e o e, he lack o sound
may lead o acciden s ha canno be a oided when using an elec ic ehicle [151].
While cha ging an elec ic ehicle in a ga age, wi hin he house, o a a public echa g-
ing s a ion, he ehicle can ca ch i e, esul ing in se ious inju ies o e en a ali ies. O he
ways an elec ic ehicle migh become dange ous include he ollowing: I a echnician
makes a mis ake when epai ing an EV, he EV can expe ience a sho ci cui as a esul .
Acciden s can happen when adjus ing he le el o an elec ic ehicle (EV) because o he
po en ial o ha m ul si ua ions, such as when he jack becomes los and acciden ally pushes
he high- ol age ba e y. Because an EV con ains so many di e en elec ical componen s,
he e is a small bu eal isk o s a ing a i e when placed on o a ow uck [148].
6. Issues in Wi eless Cha ging
In [
152
,
153
], desc ibe he p oblems now occu ing wi h WPT and he ules ha aim o
elimina e hem. One o he mos signi ican challenges ela ed o wi eless powe densi y is
i s di icul y quan i ying. Howe e , he e is limi ed con ol o e i due o he signals om
o he sou ces being e lec ed and e ac ed. Fu he mo e, p oblema ic is he planning o
powe ans e o ETs, which mus be conduc ed o op imise powe ans e and main ain
EMR sa e y [
154
]. Thi d, he unexpec ed mo emen o ER is an issue ega ding app op ia e
echnology.
The u ilized equency ange by mode n WPT sys ems is wi hin he icini y o 2.4
o 5.79 GHz. Wi hin he ITU-R adio egula ion, his band is al eady designa ed o use
by a ious adio se ices. Fo ins ance, adio local a ea ne wo ks and mic owa e o ens
ope a e on he 2.4 GHz equency, while he 5.79 GHz equency is used o DSRC-de o ed
sho - ange communica ion. The e is a possibili y ha WPT will a ec hese se ices [
155
].
The mic owa es u ilized by MPT a e o signi ican ly highe in ensi y han hose
u ilized by wi eless communica ion sys ems. The e o e, i is essen ial o keep human
sa e y in mind while ope a ing such de ices [
156
]. The alue o he SAR, o speci ic a e o
abso p ion, o he mos ealis ic e ec , is he benchma k used o de e mine whe he o no
a mic owa e is dange ous. SAR conside s hea . Hence, i is help ul because o i s highe
ele ance o po en ially ha m ul o he eyes [157].
Acco ding o he In e na ional Commission on Non-Ionizing Radia ion P o ec ion
(ICNIRP), he h eshold alue o indi iduals and he gene al public, espec i ely, is ei he
50 o 10 W/m
2
, ega dless o whe he he equency is 2.4 o 5 GHz [
158
]. The ICNIRP
has se a limi o 50 W/m
2
a 2.4 GHz and 5 GHz o people exposed on he job and
10 W/m
2
o he gene al popula ion, espec i ely [
158
]. Fu he mo e, acco ding o IEEE
s anda ds, he a e age powe densi y o e six minu es is 81.59 o 100 W/m
2
, and o e hi y
minu es, i is 16.3 o 38.7 W/m
2
[
159
]. De eloping and using wi eless powe ansmission
echnology ac oss a ious indus ies equi es i s add essing sa e y conce ns. The Global
Heal h O ganiza ion has ecen ly classi ied all adio equencies, ionizing o no , as possible
2B ca cinogens (WHO). Quan i ying he heal h e ec s o elec omagne ic adia ion is a
signi ican ocus o cu en esea ch [
160
–
162
]. Se e al s udies ha e shown ha exposu e
o mobile phone adia ion can cause cance in he b ain.
Ne e heless, he e is nil p oo o back up hese asse ions. The In e na ional Com-
mission on Non-Ionizing Radia ion P o ec ion (ICNIRP), an au ho i a i e sou ce on sa e
RF ( adio equency) exposu e, has no ye es ablished any baseline egula ions o wi e-
less cha ging [
158
]. Lack o cla i y ega ding “sa e” adia ion le els o wi eless cha ging
will pe sis un il such s anda ds a e de eloped. Because High-F equency ields can pass
h ough biological ba ie s, hey can cause pola o cha ged molecules wi hin a pe son’s
body o ib a e [
163
]. The a icle [
164
] indica es ha he Impac s o 2.49 GHz equency
EMI ha e been s udied. This in o ma ion se es as he ounda ion o WPT Cha ge s. An
incuba o has been buil [
165
] o de e mine mic owa es’ impac on human cells. Thei
indings, which o m he basis o subsequen in es iga ions in his a ea, a e as ollows:
The au ho s o he pape [
166
] c ea ed a sa e y beam and an elec omagne ic cu -o sys em
in addi ion o an incuba o o de e mine how he e ec s o mic owa es on human cells a e
Ene gies 2023,16, 4020 23 o 31
measu ed. I was concluded ha i is sa e o un a mic owa e wi eless EV cha ging sys em
o a 100 kW class o a du a ion o 30 ms [167].
When a li ing hing is subjec ed o a s ong magne ic ield, he e ha e been occasional
ins ances o he subjec expe iencing symp oms such as nausea, spinning, exhaus ion, and
changes in blood p essu e. Fo his eason, he s anda d J2954 es ablished by he Socie y
o Au omo i e Enginee s (SAE) ad ised adhe ing o he ICNIRP guideline o main ain
he low-le el magne ic ield up o a speci ic dis ance [
168
]. A me hodology known as
Haza d-Based Sa e y Enginee ing, o HBSE o sho , is a s a egy ha ocuses mainly on
haza dous sou ces o ene gy, he end up paying, and a body pa . The ol age le el in
he WPT sys em’s coils can be highe han he sou ce s eng h i sel . Elec ic shocks can
be a oided by he me ically sealing he coil conduc o , which is equi ed o p o ec he
consume s [168].
Se e al ac o s can con ibu e o he isk o a i e s a ing. Insula ion o o he elec ical
ailu es could be caused by high powe , which could hen esul in a po en ial i e haza d.
Ano he possible explana ion is ha a conduc ing objec is lying on he ansmi pad.
Because o he eddy cu en losses, he objec ’s empe a u e will ise due o his condi ion,
which could esul in he equipmen o e hea ing and ca ching i e [169,170].
7. Fu u e Pe spec i e
7.1. U iliza ion o Inno a i e Ma e ials
The ul ima e objec i e o a design o an ele a ed wi eless cha ge includes he ollow-
ing aspec s: (1) a conside able dis ance in he ai gap, (2) mo e ole ance o e misalignmen ,
(3) high powe densi y, (4) a la ge powe a ing, and e icien ope a ion. To ealize hese
design aims, a ious powe elec onics opologies, couple s, and con ol me hodologies
ha e been p esen ed up un il his poin . The majo i y o he designs ha ha e been epo ed
so a a e comp omises be ween a ious design equi emen s. Adop ing a cu ing-edge
ma e ial o a new shape o he couple can help b eak h ough he design limi s and
imp o e he o e all pe o mance.
7.2. S anda diza ion
Ano he p oblem is ha di e en manu ac u e s make powe supplies and pe manen
magne couple s ha do no wo k well oge he . When he p ima y sides ha e dis inc
lux pa e ns, he supplemen a y sides mus be changed o wo k well wi h he p ima y
side. The e o e, he in e op be ween he powe elec onics, compensa ion con igu a ion
in o ma ion, coil ypes (ci cula , DD, e c.), and geome ic pa ame e s mus be se up o
ensu e hey wo k well oge he . This is necessa y o ensu e ha he sys em equi es
compensa ion in powe elec onics, in o ma ion abou con igu a ion, and he ype o coil.
7.3. Elec omagne ic Field Tes ing and Risk Assessmen
Despi e SAE J2954 no ha ing any speci ied shielding me hods o a ious ene gy
le els han ha o WPT3, magne ic and elec ic ields emission in high-powe WPT sys ems
will in a iably cons i u e a signi ican dange o sa e y and will, hus, demand dedica ed
design. In addi ion, when he u u e elec ici y a ings climb o an amoun ha may be
p edic ed o be in he hund eds o kilowa hou s, sligh coil misalignmen will u he
con ibu e o he emissions o magne ic ields, which will make he design o he shielding
mo e challenging. As a esul , he wo s -case misalignmen scena io mus be conside ed in
conjunc ion wi h he cons ain s on he sa e y ma gin o he s ay ield.
7.4. New In eg a ion S a egies and Economic Assessmen
The ad ocacy o DWPT cha ging is p edica ed on an economic analysis o i s po en ial
bene i s. The cons uc ion o a wi eless cha ging s a ion has he po en ial o d ama ically
educe he ene gy s o age capaci y o ehicles as well as he cos s associa ed wi h pu chas-
ing ehicles. Howe e , you also ha e o hink abou he cos o he ba e ies wea ing ou ,
he oad in as uc u e, he ans o me o he dis ibu ion ne wo k, managing he powe
Ene gies 2023,16, 4020 24 o 31
quali y, and he e ec on he g id. A e his, one can comple e an e alua ion using a ious
op imiza ion objec i e unc ions.
7.5. Cons uc ion/Ins alla ion Issues
Inco po a ing a WPT sys em in o an al eady a ailable in as uc u e is a challenging
endea ou , speci ically in he case o in eg a ed s a ic and DWPT sys ems. This in icacy
mani es s i sel in se e al ways, including he ollowing: (1) he mechanical sys em may
change he magne ic cha ac e is ics o he coil; (2) he building ma e ial i sel may cause
losses; and (3) he in eg a ion o he coil should no pu he mechanical s abili y o he high-
way, mo e speci ically he compa ibili y, a isk. Du ing his ime, he ensile cha ac e is ics
o he coil need o be su icien o bea he weigh placed on he pa h.
7.6. Wi eless Powe Cha ging and Cybe secu i y
Eme ging as a new conce n abou he ene gy sa e y o WPT sys ems is he need o
ensu e ha wi eless cha ging s a ions a e secu e agains cybe a acks. As he in as uc u e
o wi eless cha ging mo es owa d g ea e powe le els, he po en ial o sys ema ic
cybe a acks on he cha ging in as uc u e is also inc easing.
8. Conclusions
This a icle aims o p o ide an o e iew o he cu en s a us o WPT esea ch and i s
uses in anspo a ion. The di icul ies and po en ial o success in e ms o echnological
ad ancemen and en i onmen al s ewa dship ha e been ou lined and explo ed. The i s
pa o his a icle was a discussion o he echnical ea u es o cha ging sys ems in h ee
di e en sec o s: (1) so magne ic ma e ial used o coil design, (2) a ious elec omagne ic
shielding, and (3) a ious induc i e pad a chi ec u es wi h wi eless s anda ds. The sys em’s
pe o mance has been boos ed due o echnological de elopmen s. Compa isons we e
made be ween he a ious pad s uc u es in e ms o pe o mance, ansmission dis ance,
in e ac ion, ole ance o inco ec alignmen , shielding, pola isa ion, in e ope abili y, mag-
ne ic lux, and cha ging zone. Pe o mance was measu ed in e ms o how a da a could
be ansmi ed.
When i comes o sus ainabili y, WPT elec ic ca s a e a ade-o be ween he bene i s
o smalle ba e ies and ligh e ehicles and he need o build a lo o in as uc u e.
Compa ed o wi ed elec ic ehicles and adi ional ehicles wi h in e nal combus ion
engines, WPT echnology has he po en ial o o e be e ene gy pe o mance, less damage
o he en i onmen , lowe li e cycle cos s, and mo e con enience and ope a ing secu i y.
To use WPT EVs o hei ulles abili y, he ollowing esea ch gaps ha e o be illed: ill in
(1) he o e sigh o he elec ical g id ha s ikes an equilib ium be ween he a ailabili y
and demand o elec ici y o ixed and mo ing ehicles, (2) op imisa ion o la ge-scale
in as uc u e o cha ging ollou and capaci y o ba e ies wi h an eye on ba e y li e
o uses such as public anspo and passenge ca s, and (3) ac ics ha in eg a e he
c ea ion and g ow h o wi eless ene gy ans e echnology alongside o he coming elec ic
ehicle me hods.
When i comes o designing and pu ing WPT EV sys ems in o place, he e a e s ill
some p oblems and chances. Wi h he help o dynamic wi eless cha ging, i will be possible
o main ain he ba e y’s cha ge while d i ing, which will make i possible o elimina e
he eno mous ba e y pack cu en ly a ba ie o he widesp ead deploymen o elec ic
ehicles and educe ange anxie y. Fo a po en ial deploymen o dynamic WPT elec ic
ehicles in he eal wo ld, se ious conside a ion mus be gi en o he en i onmen al,
economic, and sociological consequences o la ge-scale in as uc u e deploymen , as well
as he pe o mance o such in as uc u e in e ms o ene gy e ec i eness, du abili y,
and dependabili y. Gi en i s scien i ic ma u i y and inancial iabili y, s a iona y WPT
o esiden ial and business cha ging is p ojec ed o be b oadly accep ed ea lie han
dynamic cha ging. On he o he hand, dynamic WPT migh be ca ied ou slowly i he
ma ke g ows enough o educe he high ini ial acili ies cos subs an ially. Connec ed
Ene gies 2023,16, 4020 25 o 31
and au onomous ca s would p o ide g ea syne gy and accele a e he implemen a ion o
WPT echnology by using capabili ies (such as cha ging alignmen s p ecision) o enhance
d i ing pe o mance and ene gy e iciency. This would be accomplished by le e aging
capabili ies ha enhance d i ing pe o mance and ene gy e iciency. WPT echnology also
p o ides a mo e ac i e connec ion wi h he elec ical g id bidi ec ional powe ans e . This
enables elec ic ehicles o become mobile ene gy s o age uni s ha can assis in egula ing
he g id by s o ing su plus gene a ion om uncon olled enewables. The signi icance o
WPT echnology’s ole in he u he ance o ehicle elec i ica ion and he imp o emen o
he long- e m iabili y o elec i ied mobili y will be de e mined in he coming decade by
de elopmen s in WPT echnology in he a eas abo e.
Funding:
This pape was suppo ed by he ollowing p ojec TN02000025 Na ional Cen e o Ene gy
II and Go e nmen o India, Depa men o Science and Technology (DST) Science and Enginee ing
Resea ch Boa d (SERB) Co e Resea ch G an C.R.G./2020/004073.
Da a A ailabili y S a emen : No applicable.
Con lic s o In e es : The au ho s decla e no con lic o in e es .
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