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A icle
The Impac o Maximum Powe Poin T acking Algo i hms on
P ope ies o On-chip PV-based Ene gy Ha es e o IoT de ices
Adam Hudec* , Vie a S opjako a , Robe Ondica , Mi osla Po ocny and Lukas Nagy
Depa men o IC Design and Tes , Ins i u e o Elec onics and Pho onics, Facul y o Elec ical Enginee ing and
In o ma ion Technology, Slo ak Uni e si y o Technology, Ilko ico a 3, 841 04 B a isla a, Slo akia;
[email p o ec ed] (A.H.); [email p o ec ed] (V.S.); [email p o ec ed] (R.O.);
mi osla [email p o ec ed] (M.P.); [email p o ec ed] (L.N.)
*Co espondence: [email p o ec ed]
Abs ac : This a icle p esen s he analysis o selec ed maximum powe poin acking (MPPT)
1
algo i hms and hei in luence on de eloped ene gy ha es e (EH) sys em unde uni o m condi ions.
2
The ene gy ha es e is an elec onic sys em ha con e s a ailable ambien ene gy o elec ical
3
ene gy and egula es i s dis ibu ion o he ou pu . The aim is o design a ene gy ha es e wi h
4
highes in eg a ion a e possible wi h conside a ion o a ea equi emen s and low powe consump ion.
5
To imp o e he o e all ene gy con e sion o he de eloped ha es e , we implemen ed se e al MPPT
6
algo i hms (Pilo Cell, Cons an Vol age, Pe u b & Obse e) in o a dedica ed MPPT con olle
7
ha con ols he DC-DC con e e . Consequen ly, we expe imen ally analyzed hei impac on
8
he ha es e sys em. Findings shows ha e en simple algo i hms wi h smalle chip a ea and
9
lowe powe consump ion can achie e esul s compa able o mo e complex ones. The p oposed,
10
manu ac u ed and expe imen ally e alua ed EH chip p o o ype has p o en i s expec ed unc ionali y,
11
and is he e o e, ully capable o supplying ene gy o low-powe elec onics and ba e y-ope a ed
12
de ices. 13
Keywo ds: Ene gy Ha es e ; MPPT algo i hms; Con e sion E iciency; Pe u b&Obse e; Cons an
14
Vol age; Pilo -Cell 15
1. In oduc ion and Mo i a ion 16
The esea ch and de elopmen o elec onics is mos ly d i en o wa d by ac ual needs
17
o human socie y bu i is limi ed by ma e ials and echnologies o he gi en ime. Ma e ials
18
and echnologies a e he dominan ac o s in luencing he minia u iza ion o elec onic
19
sys ems o hei le el o in eg a ion on a chip. Reducing physical dimensions o componen s
20
on a chip has posi i e e ec on he powe consump ion, while inc easing he densi y o
21
componen s b ings mo e compu ing powe [
1
]. These p ope ies enable he eme gence o
22
sma and wi eless elec onics such as In e ne o Things (IoT) o wea able elec onics. 23
Recen ly, we a e app oaching a poin whe e o p o ide enough o compu ing powe
24
in a small a ea is no longe issue o many applica ions. On he o he hand, using ene gy
25
sou ces mo e e ec i ely and dec ease ene gy consump ion a e becoming mo e and mo e
26
impo an . Wea able elec onics o IoT make ex ensi e use o a ious senso sys ems o
27
which a pe manen sou ce o elec ical ene gy is una ailable and he e o e, a e powe ed
28
by ba e ies. Ba e y-powe ed sys ems ha e a ini e li espan in luenced by hei own
29
ene gy consump ion and ba e y capaci y. When he ba e y is discha ged, i needs o be
30
echa ged o eplaced. In case o wea able elec onics, his is o cou se no a p oblem bu
31
in o he applica ions like senso sys ems in ha d- o- each places o implan able medical
32
de ices, such main enance is ei he a he demanding o impossible. The e o e, i would
33
be bene icial o a oid echa ging/ eplacing ba e ies al oge he . 34
Ene gy ha es e s (EH) a e he solu ion o ex ension o he ba e y sys em li espan
35
[
2
]. EH is a sys em ha ha es s ambien ene gy om a ious sou ces (e.g. sola , he mal,
36
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mechanical, e c.) and con e s i in o elec ical ene gy. High ou pu powe is o en used in
37
p ac ice employing ene gy ha es e s ha con e sola ene gy in o elec ical one. Ene gy
38
ha es ing sys ems gene ally consis o an ene gy con e e , a ci cui ha adap s he ou pu
39
ol age alue (mos o en a DC-DC con e e ), and an ene gy s o age ha se es as he
40
main ene gy sou ce and a place whe e he excess con e ed ene gy is s o ed. Due o
41
nonlinea cha ac e is ics o Pho o-Vol aic (PV) cells o he inabili y o adap o load changes,
42
such a ha es ing sys em is no able o unc ion p ope ly and independen ly o o e he
43
maximum ene gy con e sion e iciency, and he e o e, he p esence o a con ol ci cui
44
is necessa y. In e ms o simplici y, his can be ei he a Pulse-Wid h Modula ed (PWM)
45
egula o ha d i es a powe swi ch o ene gy dis ibu ion om he sola cells o he
46
load o ba e ies. Mo e ad anced op ion is o apply DC-DC con e e o p o ide mo e
47
s able ene gy dis ibu ion using di ec PWM/PFM con ol o enhanced ci cui p o iding
48
he maximum powe poin acking (MPPT). 49
The e a e se e al known algo i hms ha can une he EH ope a ing poin , which
50
app oaches o o e laps he maximum powe poin (MPP). The MPP uning should ake
51
as li le ime as possible o elimina e he MPP d i , elimina e de o ma ions o he PV cell
52
cha ac e is ics unde pa ially shaded condi ions o adap o ma e ial deg ada ion due o
53
o e hea ing o aging. The solu ion o each o he abo e-men ioned p oblems inc eases
54
he complexi y o he MPPT algo i hm, which leads o obus ness o he espec i e digi al
55
ci cui and inc ease in he ene gy consump ion and chip a ea o e head [
3
–
5
]. Digi al ci cui s
56
p o iding he MPPT con ol a e gene ally less ene gy-hung y and occupy signi ican ly
57
less chip a ea compa ed o analog ci cui s, bu despi e hese ac s, hei inc ease in o al
58
ene gy consump ion can disable he whole ene gy ha es e . Addi ionally, i hey a e e y
59
complex, he a ea o e head migh be unaccep ably la ge. Based on his in o ma ion, one
60
may conclude ha when de eloping an ene gy ha es e , i is necessa y o ake in o accoun
61
se e al pa ame e s and make a comp omise be ween hem. This wo k he e o e ocuses on
62
he analysis o selec ed MPPT algo i hms and hei impac on he en i e ene gy ha es e
63
sys em in e ms o se e al impo an aspec s. 64
This pape is s uc u ed as ollows: Sec ion 1b ings mo i a ion o he analysis o
65
selec ed MPPT algo i hms and hei impac on he de eloped ene gy ha es e . Sec ion 2
66
desc ibes ene gy ha es ing sys ems o low-powe elec onics and o e s compa ison o
67
selec ed ene gy con e e s in e ms o he main pa ame e s. Sec ion 3p esen s ypical
68
ypes o ene gy egula ion ha can be implemen ed in sola ene gy ha es ing sys ems.
69
Sec ion 4p o ides in oduc ion in o indi ec and di ec MPPT algo i hms and summa-
70
izes ad an ages and disad an ages o each. Gene al s uc u e o he on-chip EH sys em
71
(implemen ed in 65 nm CMOS echnology) is desc ibed in Sec ion 5, which also explains
72
o he used o -chip componen s o es he whole sys em. E alua ion o p o o yped EH
73
sys em chip samples using obus measu emen se up and achie ed esul s a e p esen ed
74
Sec ion 6. Discussion abou he measu ed p ope ies o each implemen ed MPPT algo i hm
75
wi hin he EH sys em is gi en in Sec ion 7. The inal sec ion concludes he key indings
76
and op ions o possible u u e imp o emen s. 77
2. Ene gy Ha es e s 78
Ene gy ha es e s a e no a newly eme ging concep . On he con a y, hey a e well-
79
known and widely u ilized in he o m o pho o ol aic, hyd o o wind powe plan s, which
80
con e sola /mechanical ene gy in o elec ical one, ypically anging om kilowa s o
81
megawa s, and his capaci y con inues o g ow. 82
As o de ices mo e accessible o he gene al public, ene gy ha es e s ha e appea ed
83
in p oduc s like calcula o s and LED ligh s. Howe e , in ecen yea s, hey a e inc eas-
84
ingly ound in mo e complex low-powe elec onics and sys ems-on-chip (SoC). Thus, o
85
pu poses o his pape , on-chip EH sys ems will be conside ed. As men ioned in Sec ion
86
1, he enhancemen o compu a ional powe and he educ ion o ene gy consump ion
87
open doo s o he de elopmen o senso sys ems, wea able elec onics and IoT de ices.
88
A c i ical componen o such sys ems om ene gy poin o iew is ypically he powe
89
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 3 o 18
sou ce, namely he ba e y. I s abili y o supplying he ene gy o a sys em is ime-limi ed
90
and depends on he alue o elec ical load and ambien condi ions. By u ilizing ene gy
91
ha es e s, i is possible o ex end he li espan o ba e y-powe ed sys ems o in special
92
cases, e en comple ely eplace hem. 93
A signi ican ad an age o ene gy ha es e s o low-powe elec onics is he pos-
94
sibili y o applying o he ypes o ene gy con e e s (EC), such as piezoelec ic o adio
95
equency (RF) ones, in addi ion o hose al eady men ioned. I is also use ul o combine
96
mo e con e e s o c ea e so-called hyb id ene gy ha es ing sys ems. These sys ems a e
97
mo e likely o be capable o supplying elec ical ene gy o longe pe iods o ime o hey
98
may be able o p o ide powe unde condi ions whe e a s and-alone con e e would no
99
longe ha e he necessa y e iciency (such as a pho o ol aic con e e in he da k). 100
Ene gy ha es e s a e widely applicable sys ems bu he choice o he app op ia e
101
ype o ha es e depends on he speci ic applica ion. When selec ing pa ame e s such as
102
he inal loca ion as well as a ailable su ounding ene gy sou ces ha can be con e ed
103
in o elec ical ene gy, he alue o he ol age gene a ed by he espec i e con e e , i s
104
ou pu powe densi y, and las bu no leas , he physical dimensions mus be conside ed. 105
In e ms o he men ioned pa ame e s, he mos commonly used ene gy con e e in
106
EH sys ems is a sola cell. The ou pu ol age o a s andalone sola cell ypically anges in
107
hund eds o milli ol s, and by simply connec ing mul iple cells in se ies, one can achie e
108
a ol age in he ange o ol s, which is sui able o many in eg a ed ci cui s. The ene gy
109
con e sion e iciency is app oxima ely 25% and in some cases, i can each up o 50% [?].
110
Despi e he ela i ely low e iciency, he a ailable powe densi y is in hund eds o
mW/m2
,
111
which p o ides su icien ene gy o many low-powe elec onic sys ems. A compa ison o
112
pa ame e s o selec ed ene gy con e e s wi h he PV con e e is shown in Tab. 1[6–11]. 113
Table 1. Compa ison o selec ed ene gy con e e s in e ms o main pa ame e s.
Pho o ol aic The moelec ic Piezoelec ic RF
Ou pu ol age ≈600 mV 10 −100 mV 1−100 V1−4V
Ene gy 100 mW 50 −100 µW/m2
15 W0.0002 −1W
(ou side) (C)
E iciency 15 −25% 1 −13% 50 −90% 1 −90%
3. PV Ene gy Sys em Regula ion 114
The mos commonly con e ed ene gy using an ene gy ha es e is sola ene gy, due o
115
he p ope ies men ioned ea lie . By connec ing sola cells in se ies, one can achie e a highe
116
ou pu ol age, o by connec ing hem in pa allel, a highe ou pu cu en . Adjus ing he
117
ou pu powe om sola cells, whe he on he ol age o cu en side, is a ce ain adap a ion
118
o he inpu condi ions o he load. Howe e , di ec connec ion o PV cells o he load is
119
ine icien and e en dange ous, po en ially leading o des uc i e e ec s. Thus, inse ing a
120
egula o be ween he sola cell and load can signi ican ly p e en po en ial damage o he
121
load. Fu he mo e, using a egula o migh inc ease he e iciency o ene gy ha es ing. 122
Jus as he inpu condi ions o he ene gy ha es e change o e ime, so do he load
123
condi ions. The e o e, he ole o a egula o is o adjus p ope ies o he ene gy ha es e
124
o elimina e changes in condi ions, whe he a he inpu o ou pu , o he g ea es ex en
125
possible, o example, h ough pulse-wid h modula ion (PWM) o mo e ad anced me hods
126
o acking he maximum powe poin o he EH sys em. 127
3.1. PWM Regula o 128
A s aigh o wa d me hod o con olling he dis ibu ion o ene gy om he ene gy
129
ha es e inpu o load o ba e y s o age, is based on di ec connec ion/disconnec ion
130
o PV cells o he load. I s block diag am is shown in Fig. 1. PWM egula o adjus s he
131
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 4 o 18
amoun o powe ansmi ed o he ou pu o he ene gy ha es e by d i ing he powe
132
swi ch, howe e , i does no adap he ou pu ol age. To achie e he highes possible EH 133
e iciency, he ol age gene a ed a he inpu o he ene gy ha es e mus be equal o (o
134
close o) he ol age o he cha ged ba e y s o age. 135
VPV
IPV
Load
Ene gy s o age
+
-
PV
cell
PV
cell
PV
cell
PV
cell
PV
cell
PV
cell PWM con olle
VLOAD
VLOAD
Figu e 1. Block diag am o PV ene gy ha es e wi h a PWM con olle .
Unde e y high load o when he ba e y s o age is deple ed, he PWM egula o
136
(con olle ) adjus s i s ou pu so ha he cu en lowing o he load is un es ic ed, meaning
137
i is egula ed solely by he load i sel . As he load dec eases (o as ba e ies a e cha ged),
138
he du y cycle o he pulse-wid h modula ed signal is adjus ed, leading o a g adual
139
disconnec ion om he inpu . 140
Simplici y o such a sys em posi i ely impac s he cos , making i a ac i e o a ious
141
applica ions. I can eliably ans e ene gy om he ene gy ha es e inpu o i s ou pu
142
and adap o changing condi ions a bo h he inpu and ou pu o he ene gy ha es e .
143
Du ing pe iods o excess sola ene gy, pa icula ly in he summe , he sys em ope a es
144
wi h high e iciency. A i s glance, PWM egula ion seems o be a sui able choice o any 145
p ac ical applica ions whe e cos is a p ima y conce n. Howe e , i is impo an o conside
146
also he d awbacks o his egula ion me hod. One o hese is he numbe and con igu a ion
147
o sola cells necessa y. Excessi ely, high cha ging powe wi h e y deple ed ba e ies can
148
nega i ely a ec he li espan o he ba e y s o age. Las bu no leas , PWM egula o is
149
unable o ensu e ull cha ge o he ene gy s o age o su icien ol age le el o eliable
150
ope a ion o he powe ed sys em. 151
3.2. DC-DC Con e e 152
An ene gy ha es e wi h PWM egula o adjus s he ou pu powe bu canno con ol
153
he ou pu ol age. This ol age depends on he numbe o sola cells, hei in e connec ion,
154
and he in ensi y o incoming sunligh bu gene ally, is limi ed mainly by connec ing he
155
sola cells in se ies. 156
To o e come he low ol age limi imposed by he numbe o sola cells in se ies, i is
157
necessa y o inse a DC-DC con e e be ween he ene gy ha es e and he elec ical load
158
o ene gy s o age, as illus a ed in Fig. 2. Fo he DC-DC con e e o ope a e op imally
159
and e icien ly, i mus be con olled by an addi ional ci cui , o example MPPT con olle .
160
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 5 o 18
DC - DC
con e e
VPV
IPV
MPPT con olle
IPV VPV
Load
Ene gy s o age
+
-
PV
cell
PV
cell
PV
cell
PV
cell
PV
cell
PV
cell
Figu e 2. Block diag am o ene gy ha es e wi h a MPPT con olle .
3.2.1. PWM/PFM con ol 161
DC-DC con e e s a e commonly con olled by Pulse-Wid h Modula ed (PWM) o
162
Pulse-F equency Modula ed (PFM) signal. They secu e a sui able ou pu ol age by adjus -
163
ing he du y cycle o equency. 164
In he i s case, he PWM is a echnique o gene a ing a signal whose pe iod
(T)
is
165
cons an . The dynamic change o du y cycle ( a io o he du a ion o Log.1 (
Ton
) o he
166
du a ion o one pe iod) is ob ained by change o Ton.167
In he second case, he PFM gene a es a signal wi h ixed du a ion o Log.1
(Ton)
and
168
a iable du a ion o Log.0. This way he equency (and pe iod) o he con ol signal is
169
adjus ed. Fo a be e idea, he Fig. 3display he wa e o m o he PWM and PFM signals. 170
PWM
T T T
Ton1 Ton2 Ton3
PFM
T0
Ton Ton Ton
T1T2T3T4
Ton Ton
Figu e 3. PWM and PFM signal wa e o ms.
3.2.2. MPPT con ol 171
The main ole o he MPPT egula o is o e alua e he measu ed inpu pa ame e s,
172
speci ically ol age and cu en , and o adjus o shi he ope a ing poin on he powe -
173
ol age (P-V) cu e o he sola cell (Fig. 4) o he maximum powe poin ha can be
174
ob ained unde gi en condi ions, he eby maximizing ene gy ex ac ion and he e iciency
175
o he ene gy ha es e . 176
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 6 o 18
VMPP VOV
0
PMPP
PV ol age [V]
PV powe [W]
MPP
Figu e 4. P-V cu e o a sola cell and MPP acking.
In egula ing he ou pu powe o he ene gy ha es e , a wide ange o algo i hms
177
exis , each sui able o a speci ic applica ion. Simple algo i hms only need o measu e
178
one o he inpu pa ame e s, ol age o cu en , and achie e high uning speeds o he
179
ope a ing poin , albei a he cos o ne e eaching he ac ual
Vmpp
alue. Mo e complex
180
algo i hms o p ecise egula ion and achie ing highe e iciency equi e p o iding bo h
181
a iables, and i is possible o expand he inpu s o include in o ma ion abou he in ensi y
182
o ambien ligh i adia ion o empe a u e. 183
Ob aining and p ocessing inpu da a is one hing bu adap ing he ou pu ol age
184
o he DC-DC con e e based on his in o ma ion is ano he . Such a ol age adap a ion
185
is achie ed by gene a ing so-called Pulse F equency Modula ed (PFM) o Pulse Wid h
186
Modula ed (PWM) con ol signal. In he case o PFM, he ou pu ol age o he DC-DC
187
con e e is egula ed by changing he equency o he con ol signal. To achie e he
188
highes possible ol age le el, he highe equency mus be ensu ed. High equency
189
nega i ely impac s powe consump ion o he sys em, inc eases swi ching losses and
190
elec omagne ic in e e ence, and consequen ly, dec eases he o e all e iciency. 191
The second op ion is PWM egula ion, which ope a es wi h cons an con ol signal
192
equency, and he du y cycle changes. Since he swi ching equency is cons an , i is
193
accompanied by cons an losses wha c ea es an imagina y bounda y be ween PWM and
194
PFM o choose he igh con ol signal modula ion me hod. 195
A cons an swi ching equency is accompanied by cons an losses, which when small
196
in ela ion o he ansmi ed powe , make PWM con ol mo e e icien han PFM. On he
197
o he hand, i he alue o he ansmi ed powe is small, he losses when swi ching a a
198
cons an equency can exceed his alue and such con ol becomes ine icien . 199
The gene al powe anges and e iciency le els, o which he selec ed ype o modula-
200
ion o he con ol signal is sui able, a e shown in Fig. 5[12–14]. 201
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 7 o 18
0Load cu en
E iciency
PFM PWM
Figu e 5. Powe e iciency o PFM and PWM s load cu en .
4. MPPT Algo i hms 202
The mos commonly used ene gy con e e is he sola cell due o i s ela i ely high
203
ou pu ol age, p o ided powe densi y and s abili y o he ou pu powe . I s cu en -
204
ol age (I-V) cha ac e is ic o powe - ol age (P-V) ela ionship, is non-linea and ypically
205
con ains only one maximum, as shown in Fig. 4. When he ope a ing poin is loca ed
206
a he MPP on he P-V cu e, we say ha he sys em is uned o he maximum ene gy
207
ex ac ion. The posi ion o he ope a ing poin is de e mined by pa ame e s such as he
208
amoun o incoming adia ion on PV cells o he size o load. Since hese condi ions change
209
dynamically, he posi ion o he ope a ing poin shi s uncon ollably and may lead o
210
ine icien ene gy ex ac ion and po en ially disabling he en i e sys em. To con ol and se
211
he ope a ing poin o MPP posi ion, he a o emen ioned PWM egula o is commonly used,
212
due o i s simplici y. To ob ain highe powe con e sion e iciency and highe accu acy, he
213
mo e ad anced egula o based on MPPT algo i hms[
15
] can be implemen ed. Based on
214
he ype o inpu s and he me hod o uning he ope a ing poin , MPPT algo i hms can be
215
ca ego ized in o wo g oups: indi ec and di ec algo i hms. 216
4.1. Indi ec Algo i hms 217
Indi ec MPPT algo i hms can be desc ibed as algo i hms ha p ima ily wo k wi h
218
s a ic a iables. They p ocess in o ma ion om a gene al model o da a ob ained om p e-
219
applica ion cha ac e iza ion o he PV cell. This in ol es labo a o y measu emen s acqui ed
220
om he I-V and P-V cu es in an unloaded s a e, om which we can ex ac impo an
221
pa ame e s such as open-ci cui ol age
VOV
, sho -ci cui cu en
ISC
, and ol age
VMPP 222
and cu en IMPP a he MPP. 223
Based on he ob ained da a, i is possible o achie e he p ope se ing o he ope a ing
224
poin o he ene gy con e e o he maximum ene gy ex ac ion. Howe e , i is no
225
possible o dynamically espond o changes in inpu condi ions caused by ac o s such
226
as changes in illumina ion, pa ial shading o he PV cell, and las bu no leas , ma e ial
227
deg ada ion due o aging. Indi idual indi ec algo i hms, by hei e y na u e, will ne e
228
each he ac ual MPP bu will app oach and oscilla e in i s icini y. 229
Despi e he a o emen ioned d awbacks o indi ec algo i hms, some o hem a e e y
230
in e es ing o many applica ions. Fo example, algo i hms like Cons an Vol age (CV)[
16
],
231
Pilo -cell (PC), F ac ional Open Ci cui Vol age (FOCV), F ac ional Sho Ci cui Cu en
232
(FSCC)[
17
], and o he s domina e in speed o uning he ope a ing poin and a e ha dwa e-
233
simple, which means hey a e no demanding in e ms o a ea size and elec ical ene gy
234
consump ion. 235
4.2. Di ec Algo i hms 236
Di ec MPPT algo i hms con inuously adjus he ope a ional poin o he ene gy
237
ha es e based on eal- ime measu emen s o ol age
VPV
and cu en
IPV
, and hus
238
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 8 o 18
powe
PPV
, using an analog- o-digi al con e e . They do no equi e disconnec ing he
239
sola cell om he es o he ci cui , as is he case wi h some indi ec algo i hms. 240
Addi ionally, in con as o indi ec MPPT algo i hms, di ec MPPT algo i hms do no
241
equi e absolu e knowledge o he I-V and P-V cu es o he sola cell. Ins ead, hey can
242
dynamically adap o changes in inpu condi ions such as ligh ing, pa ial shading o he
243
PV panel, empe a u e, and e en ma e ial deg ada ion. 244
The ope a ion o di ec algo i hms using ela i e alues—speci ically by compa ing
245
cu en and p e ious measu emen s—enables he ene gy ha es e o unc ion e ec i ely 246
ac oss a wide ange o condi ions while main aining he highes possible ex ac ion e i-
247
ciency. 248
Cha ac e is ics such as high accu acy in uning he ope a ional poin , esponsi e-
249
ness o dynamic changes, and high e iciency a e ypical ea u es o e en he simples
250
di ec algo i hms, such as Pe u b and Obse e (P&O)[
18
] and Inc emen al Conduc ance
251
(IncCond)[
19
]. O cou se, he e a e also many o he algo i hms, pa icula ly hose based on
252
uzzy logic[
20
] o a i icial in elligence[
21
], which can be e manage local maximum on
253
he P-V cu e gene a ed by pa ially shaded PV panels o can elimina e MPPT d i [
22
].
254
Howe e , such algo i hms may equi e signi ican ly mo e complex ha dwa e and highe
255
compu a ional powe . 256
A compa ison o he p ope ies o indi ec and di ec algo i hms ope a ing unde
257
uni o m condi ions is p esen ed in Tab. 2.258
Table 2. Compa ison o selec ed indi ec and di ec MPPT algo i hms unde uni o m condi ions.
Algo i hm PV Cell Dependecy Senso T acking Speed E iciency
V I
Cons an Vol age YES •FAST LOW
Open Ci cui Vol age YES •FAST LOW
Sho Ci cui Cu en YES •FAST LOW
Pilo -Cell YES •FAST LOW
Pe u b & Obse e NO • • SLOW HIGH
Inc emen al Conduc ance NO • • MEDIUM HIGH
5. De eloped On-chip Ene gy Ha es e 259
We ha e designed an ene gy ha es e ha con e s sola ene gy in o elec ical ene gy.
260
This is a ela i ely complex mic oelec onic sys em, whe e he goal was o achie e he
261
highes possible le el o in eg a ion on a chip using s anda d 65 nm CMOS echnology. I s
262
simpli ied block diag am is depic ed in Fig. 6, This igu e illus a es pa s ha ha e been
263
in eg a ed on o he chip and also disc e e componen s used ex e nally.
PV
POWER
PV
SENSE
TRIM
FILTER
ONESHOTOSCMPPT
+
-
M3M_TUNE
CS_TUNE
VPV
V e
DC-DC CONVERTER SHUNT
REGULATOR
OFF-CHIP COMPONENTS
ON-CHIP COMPONENTS
REGISTERS PC
Figu e 6. Simpli ied block diag am o he p oposed on-chip ene gy ha es e .
264
5.1. On-chip Componen s 265
Pa s o he EH sys em in eg a ed on a chip a e he ollowing. 266
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 9 o 18
•
DC-DC Con e e : P oposed ol age con e e speci ically o ope a ion wi h a
267
cus om designed and ully-in eg a ed induc o on a chip [
23
–
26
] is based on he
268
Con en ional Boos Con e e (CBC) opology [
27
,
28
]. I s co e componen s, such as
269
powe swi ches, induc o and pa o he inpu capaci o a e ully in eg a ed on he
270
chip. The low-side powe swi ch is con olled by PFM signal gene a ed by con ol
271
loop and he high-side powe swi ch is d i en as ideal diode wi h ze o h eshold
272
ol age by Ze o Cu en C ossing De ec o (ZCCD) [29] ha is pa o he con e e . 273
•
Con ol Loop: The con ol loop adjus s he inpu impedance o he DC-DC con e e
274
and in his way, e ec i ely shi s he EH ope a ing poin o a posi ion ha ensu es he
275
maximum ene gy ex ac ion om he inpu unde gi en condi ions. This ene gy is
276
ans e ed o he ou pu o he ene gy ha es e . Main componen s o he con ol loop
277
a e ully in eg a ed on a chip. The co e o he con ol loop consis s o he ollowing
278
ci cui s: 279
–
Regis e s: The ene gy ha es e is a complex elec onic sys em in eg a ed on
280
a chip wi h a ge ed pa ame e s. Du ing he IC manu ac u ing, luc ua ion o
281
p ocess occu s ha may a ec he EH sys em pa ame e s. Fo his eason, we
282
ha e added he capabili y o ce ain co ec ions/modi ica ions o pa ame e s
283
using compensa ion banks, uning banks and swi ches ha can be con olled
284
ex e nally h ough egis e memo y, i.e. ia a compu e . In he case o he MPPT
285
block, i is possible o adjus he ini ializa ion pa ame e s, change he ype o
286
in e nal MPPT algo i hm o ac i a e he op ion o connec ing an ex e nal MPPT
287
ci cui implemen ed in a Field P og ammable Ga e A ay (FPGA) o m. The ene gy
288
ha es e con ains a ela i ely la ge numbe o egis e s. Fo be e con ol and
289
in e ac ion wi h egis e s du ing measu emen , a cus om G aphical Use In e ace
290
(GUI) was de eloped in Py hon p og amming language using he Tkin e ool.
291
The de eloped GUI is shown in Fig. 7.
Figu e 7. G aphical Use In e ace o manipula ing he egis e s con en .
292
–
MPPT: The egula ion o ene gy ans e om he ene gy con e e inpu o
293
i s ou pu is managed by a con ol signal, which can be o he PWM ype o
294
PFM ype. Since he en i e sys em was designed o low-powe applica ions,
295
we implemen ed a ci cui o gene a ing a PFM signal. The gene a ion o he
296
p ope equency o he con ol signal is de e mined by a ci cui ope a ing on he
297
MPPT algo i hm. Depending on he algo i hm ype, a ious inpu in o ma ion
298
is e alua ed, such as a 1-bi compa ison esul o ol ages on he loaded and
299
e e ence sola cells o Pilo -Cell (PC) algo i hm o in he case o Cons an Vol age
300
(CV) and Pe u b & Obse e (P&O) algo i hms, i in ol es 10-bi numbe s om
301
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 16 o 18
Figu e 18. Spide cha ep esen ing key p ope ies o each inspec ed MPPT algo i hm.
cycles). I occupies he smalles a ea o 1258
µm2
and i s e o a e anges om 3.05 % o
460
11.52 %. 461
8. Conclusion 462
We ha e designed an ene gy ha es e ASIC in ended o low-powe elec onics ha
463
was p o o yped using 65 nm CMOS echnology by UMC. Mos o he sys em componen s,
464
such as he DC-DC con e e , MPPT con olle , elaxa ion oscilla o , and one-sho oscil-
465
la o ha e been ully in eg a ed on he chip. O he componen s such as shun egula o ,
466
e alua ion and measu emen ci cui s (i.e. a ol age compa a o and ADC con e e ), and
467
PV cells we e used in disc e e o m. Di e en algo i hms we e implemen ed in he MPPT
468
con olle and hei p ope ies compa ed o ind he mos p ope solu ion o inc easing he
469
o e all EH e iciency. Indi ec MPPT algo i hms equi e in o ma ion abou he ol age o
470
loaded sola cell (
VPV
) and he ol age o unloaded sola cell (
VOV
). In p ac ice, his means
471
ha o ob ain he necessa y
VOV
, i is essen ial o disconnec he sola cells om he es
472
o he ci cui , p e en ing ene gy ans e o a b ie momen . To a oid in e up ing he
473
supply o con e ed ene gy, we ins alled ano he iden ical pai o sola cells nex o he
474
exis ing one. This con igu a ion p o ides
VPV
om one pai o sola cells and
VMPP
om
475
he o he . To manage he ene gy ex ac ion om he a o emen ioned sola cell assembly, he
476
Pilo -Cell MPPT algo i hm was used. I s selec ed ea u es can be con igu ed using egis e s
477
con ollable ia a compu e . I is possible o choose whe he he algo i hm will ope a e
478
wi h an adap i e o s a ic s ep. In he case o a s a ic s ep, he size o con e gence s ep
479
anging om 1 o 31 can be selec ed. 480
F om pe o med measu emen s o ASIC samples and esul s ob ained by applying
481
indi idual MPPT algo i hms, we e alua ed he main pa ame e s such as a ea, powe
482
consump ion, e o om he MPP, oscilla ion ange and speed o con e gence. Based on
483
hese da a, compa ison o MPPT algo i hms was made. 484
Fi s ly, he Pilo -Cell algo i hm was analyzed. I p ocesses 1-bi in o ma ion om he
485
compa a o . In e ms o ene gy consump ion and oscilla ion ange, i achie es he lowes
486
alues among he o he s, hus domina ing in wo key pa ame e s ou o i e. The second
487
analyzed algo i hm was Cons an Vol age, which is simila o PC in i s ope a ing p inciple.
488
Howe e , i wo ks wi h mul i-bi in o ma ion om he ADC con e e . A ibu es such as
489
ene gy consump ion and oscilla ion ange acqui e highe alues han PC, bu as o e o ,
490
speed o con e gence and a ea, i achie es lowe alues. This means ha i domina es
491
in 3 ou o 5 e alua ed aspec s. The las in es iga ed algo i hm is P&O. I is classi ied
492
as a di ec algo i hm and uses ol age and cu en in o ma ion om he ADC con e e .
493
This ype o algo i hm achie es he wo s esul s in ene gy consump ion, size o a ea and
494
Ve sion No embe 25, 2025 submi ed o Jou nal No Speci ied 17 o 18
con e gence speed. As o he e o o he MPP and oscilla ion ange, he achie ed alues
495
a e compa able o o he MPPT algo i hms. 496
Acco ding o he analysis desc ibed abo e, he CV algo i hm achie es he bes esul s
497
among he e alua ed MPPT algo i hms. The d awback is ene gy consump ion and i s
498
educ ion will be one o he goals o he u u e wo k. The PC algo i hm also achie es
499
excellen esul s, bu despi e he ac ha i p ocesses 1-bi in o ma ion om he compa a o ,
500
i equi es la ge a ea on he chip han CV. In his ega d, i will also be necessa y o pe o m
501
op imiza ion s eps pe a ea. The mos complex analyzed algo i hm P&O lags behind in
502
se e al pa ame e s. Despi e he mo e un a o able p ope ies, we see a g ea po en ial o
503
u u e imp o emen s. The e o will be o ge as close as possible o indi ec algo i hms
504
p ope ies, especially as o speed o con e gence and powe consump ion. 505
Au ho Con ibu ions: In es iga ion A.H. and R.O.; concep ualiza ion V.S. and A.H.; w i ing—o iginal
506
d a p epa a ion, A.H. and V.S.; w i ing— e iew and edi ing, A.H., R.O. and V.S.; me hodology,
507
A.H., R.O., M.P. and L.N.; alida ion, R.O., M.P. and L.N. All au ho s ha e ead and ag eed o he
508
published e sion o he manusc ip . 509
Funding: This wo k was suppo ed by g an s VEGA 1/0705/24 and VEGA 1/0572/25, and he
510
Slo ak Resea ch and De elopmen Agency unde g an s APVV-23-0071 and VV-MVP-24-0313. This
511
wo k has also ecei ed unding om he Chips Join Unde aking unde g an ag eemen numbe
512
101139790 and i s membe s, including he op-up unding by Ge many, I aly, Slo akia, Spain and The
513
Ne he lands. This esea ch was done in he amewo k o "Ma ching“ G an No.09I01-03-V04-00030
514
om Reco e y and Resilience Plan o he Slo ak Republic. 515
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