ArticlePDF Available

Abstract and Figures

In this paper, a non isolated interleaved, dc/dc boost converter with a high efficiency is proposed for using in photovoltaic system applications. For realizing zero voltage soft switching (ZVS), two active clamp circuits are used for each phases of the boost converter. By utilizing a voltage doubler configuration at the converter’s output terminal and connecting the secondary side of coupled inductors in series, high conversion ration can be achieved. The capacitor is also connected in series with output capacitors to transfer leakage energy to the output. Interleaved structure is used in input side to minimize current ripple and reduce magnetic component. So, the converter not only operates with a higher voltage gain, but also is able to operate more efficiently and can be used in photovoltaic (PV) applications.
Content may be subject to copyright.
International Journal of Soft Computing and Engineering (IJSCE)
ISSN: 2231-2307, Volume-6 Issue-2, May 2016
31
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
A High Efficiency DC/DC Boost Converter for
Photovoltaic Applications
Peyman Khazaei, Syyed Mojtaba Modares, Morteza Dabbaghjamanesh, Motab Almousa, Amirhossein
Moeini
Abstract— In this paper, a non isolated interleaved, dc/dc boost
converter with a high efficiency is proposed for using in
photovoltaic system applications. For realizing zero voltage soft
switching (ZVS), two active clamp circuits are used for each
phases of the boost converter. By utilizing a voltage doubler
configuration at the converter’s output terminal and connecting
the secondary side of coupled inductors in series, high conversion
ration can be achieved. The capacitor is also connected in series
with output capacitors to transfer leakage energy to the output.
Interleaved structure is used in input side to minimize current
ripple and reduce magnetic component. So, the converter not
only operates with a higher voltage gain, but also is able to
operate more efficiently and can be used in photovoltaic (PV)
applications.
Keywords-high voltage gain; interleaved DC-DC boost
converter; photovoltaic system; soft switching performance.
I. INTRODUCTION
Chiefly, utilizing high performance dc-dc boost
converters is an essential factor in renewable energy sources
in high power applications. High efficiency, high voltage
gain and being non-isolated are the main features for
renewable energies applications [1]. Ideally, a boost
converter can reach a very high voltage gain with an
unlimited duty cycle, however the turn off period of switches
will be small when the duty cycle gets increased. The ripples
in the current waveform corresponding to power devices get
increased and as a result the power losses increase.
Furthermore, the voltage stresses across for both switch and
diode are identical to the output voltage [2]. The interleaved
structure can be considered as a feasible solution to enhance
the performance, mitigate ripples in the current, reduce the
size of the passive components and also accelerate the
transient response [3-4]. The coupled inductor is utilized to
reduce not only the duty ratio but also the voltage stress
across the switches. Therefore, for applications for which a
high voltage gain is needed, the boost converter with the
coupled inductor can be more efficient compared to the
conventional design [5]. Different active and passive soft
switching interleaved step-up converters in which coupled
inductor is utilized are proposed for loss reduction purposes.
[6-8].
Revised Version Manuscript Received on May 03, 2016.
Peyman Khazaei, Department of Electrical and Computer Engineering,
Louisiana State University, Baton Rouge, LA
Syyed Mojtaba Modares, Department of Electrical and Computer
Engineering, Louisiana State University, Baton Rouge, LA
Morteza Dabbaghjamanesh, Department of Electrical and Computer
Engineering, Louisiana State University, Baton Rouge, LA
Motab Almousa, Department of Electrical and Computer Engineering,
Prince Sattam Bin Abdulaziz University, Saudi Arabia.
Amirhossein Moeini, Department of Electrical and Computer
Engineering, University of Florida, Gainesville, FL.
However, most of them are considered for the Power Factor
Correction (PFC) applications and not an appropriate option
for PV systems for which a DC-DC boost converter with a
high step-up gain is required.
Some interleaved converters are proposed by adding
capacitor cells to the typical interleaved boost converter [9-
10]. However, a considerable number of capacitors are
required to reach a high voltage gain that increases the
complexity in the converter. Different types of interleaved
converters with coupled inductors are well investigated in
[11-13], which can reach high step-up gain by an appropriate
topology. Unfortunately, the maximum numbers of
interleaved phases are only two in these converters and
cannot be designed for any number of phases. Also, the
voltage stress across the diode in the output is greater than
the output voltage.
In this paper, an efficient interleaved converter is
proposed for PV system applications. The interleaved
structure in input side and cascaded configuration in output
side is utilized therefore, there would not be any problem
with a high amount of current and voltage in the input and
output. By utilizing the active clamp design, both the clamp
and main switches work in the zero voltage soft switching
condition. A snubber capacitor in series with output
capacitors is inserted to recycle the leakage energy. So,
switching losses are reduced significantly. When a coupled
inductor is utilized in fly-back condition the other coupled
inductor operates in forwarding condition to transfer energy
to output side, due to interleaved control. The proposed
topology and operational stages are discussed in section ІІ. In
the third section of this paper, the design guidelines of the
converter are given. In section IV the simulation result and
waveforms are illustrated.
II.
PROPOSED
CONVERTER
TOPOLOGY
The topology of the proposed converter is shown in Fig.
1. The main switches S
1
and S
2
work in the interleaved
control. The active clamp circuits are composed of auxiliary
switches S
C1
and S
C2
, and clamp capacitors C
C1
and C
C2
,
which are utilized to recycle the leakage energy and suppress
the turn-off spike voltage on the main switches, and realize
zero voltage soft switching. There are two coupled inductors,
which L
1a
and L
2a
with n
1
turns which have been coupled
with their corresponding inductors L
1b
and L
2b
with n
2
turns.
The L
m1
and L
m2
are the magnetizing inductors, and L
k1
and
L
k2
are the leakage inductances of coupled inductors. N
represents the turn ratio n
2
/n
1
. The couples reference are
marked by "*" and "•". The C
o1
, C
o2
and C
o3
are the output
capacitors and D
o1
, D
o2
, D
o3
and D
o4
are the output diodes.
Moreover, the capacitor C
o3
works as snubber capacitor, to
recycles the leakage energy in the coupled inductor. There
are 16 main stages in one switching period. Because of the
A High Efficiency DC/DC Boost Converter for Photovoltaic Applications
32
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
symmetrical structure of the converter, only half of 16 stages
are considered. The steady state profiles are depicted in Fig.
2. In Fig.3 corresponding circuit of each stage is illustrated.
Figure 1. proposed ZVT boost converter.
Figure 2. Key waveforms of proposed converter.
Time interval [t
0
, t
1
]: the main switches S
1
and S
2
conduct, and the clamp switches S
C1
and S
C2
are in OFF state.
All diodes are in reverse biased. The current flowing though
the magnetizing inductors L
m1
and L
m2
increases by input
voltage linearly.
)()()(
0
11
011
tt
LL
V
tIti
km
in
mLmL
+
+=
(1)
)()()(
0
22
022
tt
LL
V
tIti
km
in
mLmL
+
+=
(2)
Time interval [t
1
, t
2
]: at the beginning of this time
interval, the main switch S
2
goes to the OFF state, then the
corresponding capacitor C
S2
is energized by the current i
Lm2
.
Capacitor C
S2
causes the main switch S
2
gets OFF with ZVS
condition. At t
2
, voltage of main switch S
2
becomes equal to
clamp capacitor C
C2
.
)(
)(
)(
1
2
12
2
tt
C
tI
tv
s
mL
sd
=
(3)
Time interval [t
2
, t
3
]: at t
2
, charging of switch S
2
leads to
diode D
o1
and the inverse-parallel diode of the switch S
C2
begin to conduct, and the leakage energy transfer to output.
The coupled inductor L
1
works as transformer and forward
mode and the coupled inductor L
2
works as flyback converter
to supply energy to the load in the output. The leakage
inductance L
k2
and the capacitor C
C2
, make a resonance
circuit. The circuit operation at this stage is according to the
following formula:
)(cos)()(
21222
tttIti
mLkL
ω= (4)
)(sin)()(
212032
tttIZVtv
kLOCC
ω+= (5)
1111
)(
oDmLkLs
iNtIii +== (6)
Where
22
1
.
1
Ck
CL
=ω
Time interval [t
3
, t
4
]: at t
3
, the switch S
C2
conducts in
ZVS condition, as its inverse-parallel is conducting. The
voltage across the capacitor C
C2
will be equal to the voltage
across the output capacitor C
o3
. Therefore, the diode D
o4
begins to conduct.
Time interval [t
4
, t
5
]: at t
4
, the current of diode D
o4
falls to
zero and then the current of clamp capacitor C
C2
becomes
equal to the current leakage inductance L
k2
[33].
Time interval [t
5
, t
6
]: at the beginning of this time period,
the clamp switch S
C2
gets OFF. While the voltage across the
capacitor C
S2
drops, the voltage across the S
C2
rises with a
same degree. Thus, the switch S
C2
gets off with ZVS
performance. The capacitor C
C2
is disconnected from
converter and the L
k2
starts to resonance with the C
S2
.
)](sin1)[()(
52522
tttIti
LkLk
ω=
(7)
)](cos1[
.)(
)()(
52
22
5
522
tt
CtI
tVtv
S
Lk
sSdSd
ω
ω
=
(8)
Where
22
2
.
1
sk
CL
=ω
L
2a
L
1
a
L
1b
L
2b
International Journal of Soft Computing and Engineering (IJSCE)
ISSN: 2231-2307, Volume-6 Issue-2, May 2016
33
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
(2)
(1)
(4)
(3)
(6)
(5)
(8)
(7)
Figure 3. Different stages of the converter: (1) interval 1 (t
0
- t
1
), (2) interval 2 (t
1
- t
2
), (3) interval 3 (t
2
-t
3
), (4) interval
4 (t
3
- t
4
), (5) interval 5 (t
4
- t
5
), (6) interval 6 (t
5
- t
6
), (7) interval 7 (t
6
- t
7
), (8) interval 8 (t
7
- t
8
)
Time interval [t
6
, t
7
]: Initially, the voltage across the
switch S
2
is zero. Therefore, the corresponding diode of the
switch S
2
starts to operate in the conducting mode. The
current through L
k2
increases linearly, which controls
declining rate of the output diode D
o1
.
)(
)()(
21
2
1
611 kk
oC
oDoD
LLN
V
titi +
=
(9)
Time interval [t
7
, t
8
]: at the beginning of this interval, the
main switch S
2
will be ON with ZVS soft switching
performance due to its inverse-parallel diode which conducts.
At t
8
, the leakage current L
k2
reaches zero and the diode D
o1
goes to the OFF state while the current is zero. The input
voltage will charge two main inductors. A same pattern
occurs in the rest of the switching time.
A High Efficiency DC/DC Boost Converter for Photovoltaic Applications
34
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
III. DESIGN
GUIDELINES
If the leakage inductance is zero (ideal condition),
conduction resistance as well as the voltage drop are
negligible. The voltage of the clamp and output capacitors
can be acquired using equations (10) and (11):
V
VV
in
oCcC
==
1
3 (10)
VN
VV
in
oCoC
==
1
21 (11)
Where D is the duty cycle for the main switch. The
output voltage is summation of the output capacitors.
Therefore, the voltage gain is:
D
N
V
V
M
in
out
+
== 1
1.2
(12)
Equation (13) indicates the equality of the voltage across
the clamp capacitors and the voltage stress across the power
switches.
121
&_
+
=
=N
V
D
V
V
outin
clampmainstress
(13)
The voltage stress across the switches is proportional to
the coupled inductor’s turn ratio. Therefore, by selecting a
proper turn ratio the voltage switch stress can be reduced. All
active switches are turned off with ZVS due to parallel
capacitors C
S1
and C
S2
.
The clamp switches are in the ON state under ZVS
condition as their corresponding inverse-parallel diodes are
conducting when switches S
C1
and S
C2
turn on. To meet the
ZVS ON state of main switches, all the energy in parallel
capacitor of the main switch has to be transferred to leakage
inductance. Therefore, when the main switch is in the ON
state, the stored energy in the leakage inductance has to be
greater than the amount of energy in the parallel capacitor.
Therefore, the zero voltage switching-ON performance of
main switches is obtained from energy consideration:
2
1
2
)
12
(
4
2+
N
V
C
I
L
out
S
in
K
(14)
As a result:
22
2
)12(
2
in
outS
K
IN
VC
L+
(15)
The relationship of leakage inductance versus input
current in different turn ratio is plotted in Fig. 4. The required
leakage inductance in ZVS condition decreases as the input
current increases. Equation (16) shows the proper
determination of the clamp capacitor [14]:
2
2
2
2
)1(
sK
C
fL
D
Cπ
(16)
The magnetizing inductor and the output capacitor are
determined by considering a permissible percentage of ripple
in the inductor current and proper voltage ripple on the
output capacitor voltage [15].
Figure 4. Relation of leakage inductance, and input
current, and turns ratio.
IV.
SIMULATION RESULTS
A PV array is used instead of the dc source of proposed
converter in simulation. The parameters of PV modules are
presented in table І. Four PV modules are connected in series
and parallel to obtain high power level. Table ІІ shows
converter parameters. In order to achieve maximum power
from PV array, average current control and maximum power
point tracking (MPPT) control have been used. The voltage
in MPP is computed by using IncCon MPPT method
described in [16] and it is compared with extracted PV
voltage. The difference between them is used as an input for
voltage controller [17-24]. By comparing the output of
current controller with carrier wave, appropriate pulse for the
gate of main switch is generated. The phase difference
between each gate signal is 180°, because there are two
phases in proposed interleaved boost converter [25-32].
Fig. 5 illustrates control algorithm of the converter topology.
The gate signals of the clamp switches S
C1
and S
C2
are
complement with the gate signals for main switches S
1
and
S
2
. Fig. 6 shows the voltage, current and power profiles of
output PV array without and with MPPT and with irradiance
change. The currents of leakage inductances and input
current are illustrated in Fig. 7. The ripple in the input current
is not considerable because of the interleaved design. The
voltage and current of clamp capacitor are shown in Fig. 8.
Fig. 9 indicates the switching transition of the main and the
clamp switches. It is shown that all power switches of
converter are operating with zero voltage soft switching
performance for the entire switching period that mitigates the
power losses. The voltage and current profiles of the diode
D
o1
are depicted in Fig. 10.
TABLE I.
PV
M
ODULE CHARACTERISTICS
Model: RECAE220-us
Max. output power, P
max
(W) 220
Open circuit voltage, V
OC
(V) 36.6
International Journal of Soft Computing and Engineering (IJSCE)
ISSN: 2231-2307, Volume-6 Issue-2, May 2016
35
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
MPPT voltage, V
MPPT
(V) 28.7
Short circuit current, I
SC
(A) 8.2
MPPT current, I
MPPT
(A) 7.7
TABLE II.
K
EY PARAMETERS OF THE CONVERTER
Input Voltage, V
in
(V) 59 Magnetizing inductor, L
m
(uH) 130
Output voltage, V
out
(V) 520 Output capacitors, Co
(uF) 50
Output power, P
out
(W) 880 Turns ratio, N 1:1
Main switches frequency,
f
s
(KHz) 100 Leakage inductances, L
k1
and L
k2
(uH) 1.5
Clamp Capacitors, C
C1
and C
C
2
(uF) 3 Parallel capacitors, C
S1
and C
S
2
(nF) 1
Figure 5. Control algorithm of the proposed converter
Figure 6.Voltage, current and Power of PV at without
and with MPPT and irradiance change.
Figure 7. Input current i
Lk1
, i
Lk2
, and I
in
Figure 8.Voltage and current of the clamp circuit.
Figure 9. ZVT performance of (a) main switch, (b) clamp
switch.
Figure 10.Voltage and current of diod D
o1
.
The voltage stress across the diode is
out
V
NN122+, which
is less than the output voltage. The declining rate of the
current through diode is controlled by leakage inductance. A
comparison of measured efficiency at different levels of load
for this proposed converter and the converter introduced in
[13], is given in Fig. 11. There is approximately 3%
A High Efficiency DC/DC Boost Converter for Photovoltaic Applications
36
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
improvement in efficiency compared with the converter
proposed in [13] at 880W full load under the same testing
scenario. The efficiency is enhanced with a less complicated
configuration in comparison to the converter in [13].
Figure 11. Measured efficiency comparison at different
percent loads.
V. CONCLUSION
An efficient high voltage gain ZVS non-isolated
converter with interleaved structure in input and voltage
doubler structure in output of for PV system has been
proposed in this paper. Zero voltage soft switching
performance is realized by active clamp circuit to mitigate
the power losses. The proposed converter also uses switches
with low turn on resistance and voltage rate. Furthermore,
due to interleaved operation the input current ripple can be
mitigated. The steady state waveforms and stages analysis
and design guidelines are discussed. At last, simulation
results of converter with PV array 880W, 59V, 520V are
presented. Simulation results confirm that the proposed
interleaved converter is an appropriate option for conversions
in which the high voltage gain and efficiency are two
important factors.
R
EFERENCES
1. Zhao, Q., and Lee, F.C.: ‘High-efficiency high step-up DC/DC
converters’, IEEE Trans. Power Electron., 2003, 1, (1), pp. 65–73.
2. S. Dwari and L. Parsa, "An efficient high-step-up interleaved DC–
DC converter with a common active clamp," Power Electronics,
IEEE Transactions on, vol. 26, pp. 66-78, 2011.
3. W. Li, J. Liu, J. Wu, and X. He, “Design and analysis of isolated
ZVT boost converters for high-efficiency and high-step-up
applications,” IEEE Trans. Power Electron., vol. 22, no. 6, pp.
2363–2374, Nov. 2007.
4. X. Kong and A. M. Khambadkone, “Analysis and implementation of
a high efficiency, interleaved current-fed full bridge converter for
fuel cell system,” IEEE Trans. Power Electron., vol. 22, no. 2, pp.
543–550, Mar. 2007.
5. W. Li and X. He, “An interleaved winding-coupled boost converter
with passive lossless clamp circuits,” IEEE Trans. Power Electron.,
vol. 22, no. 4, pp. 1499–1507, Jul. 2007.
6. W. Li and X. He, "Review of nonisolated high-step-up DC/DC
converters in photovoltaic grid-connected applications," Industrial
Electronics, IEEE Transactions on, vol. 58, pp. 1239-1250, 2011.
7. G. Yao, A. Chen, and X. He, “Soft switching circuit for interleaved
boost converters,” IEEE Trans. Power Electron., vol. 22, no. 1, pp.
80–86, Jan. 2007.
8. X. Huang, X. Wang, T. Nergaard, J. S. Lai, X. Xu, and L. Zhu,
“Parasitic ringing and design issues of digitally controlled high
power interleaved boost converters,” IEEE Trans. Power Electron.,
vol. 19, no. 5, pp. 1341–1352, Sep. 2004.
9. E. H. Ismail, M. A. Al-Saffar, A. J. Sabzali, and A. A. Fardoun, "A
family of single-switch PWM converters with high step-up
conversion ratio," Circuits and Systems I: Regular Papers, IEEE
Transactions on, vol. 55, pp. 1159-1171, 2008.
10. E. H. Ismail, M. A. Al-Saffar, and A. J. Sabzali, "High conversion
ratio DC–DC converters with reduced switch stress," Circuits and
Systems I: Regular Papers, IEEE Transactions on, vol. 55, pp. 2139-
2151, 2008.
11. W. Li and X. He, "High step-up soft switching interleaved boost
converters with cross-winding-coupled inductors and reduced
auxiliary switch number," Power Electronics, IET, vol. 2, pp. 125-
133, 2009.
12. W. Li and X. He, "A Family of Interleaved DC–DC Converters
DeducedFrom a Basic Cell With Winding-Cross-CoupledInductors
(WCCIs) for High Step-Upor Step-Down Conversions," Power
Electronics, IEEE Transactions on, vol. 23, pp. 1791-1801, 2008.
13. W. Li and X. He, "ZVT interleaved boost converters for high-
efficiency, high step-up DC-DC conversion," Electric Power
Applications, IET, vol. 1, pp. 284-290, 2007.
14. R. Watson, F. C. Lee, and G. C. Hua, “Utilization of an active-clamp
circuit to achieve soft switching in flyback converters,” IEEE Trans.
Power Electron., vol. 11, no. 1, pp. 162–169, Jan. 1996.
15. U. Product, "Applications Handbook 1995–1996," ed: Unitrode
Corp., Merrimack, NH, 1995.
16. T. Esram and P. L. Chapman, "Comparison of photovoltaic array
maximum power point tracking techniques," Energy conversion,
IEEE transactions on, vol. 22, pp. 439-449, 2007.
17. Sajjadi, S. M., Yazdankhah, A. S., & Ferdowsi, F. (2012). A new
gumption approach for economic
dispatch problem with losses
effect based on valve-point active power. Electric Power Systems
Research, 92, 81-86.
18. Ferdowsi, F., Yazdankhah, A. S., & Abbasi, B. (2012, May).
Declining power fluctuation velocity in large PV systems by optimal
battery selection. InEnvironment and Electrical Engineering
(EEEIC), 2012
11th International Conference on (pp. 983-988).
IEEE.
19. Dabbaghjamanesh.M, Moeini .A,Ashkaboosi .M, Khazaei .P,
Mirzapalangi .K (2015). High Performance Control of Grid
Connected Cascaded H-Bridge Active Rectifier based on Type II-
Fuzzy Logic Controller with Low Frequency Modulation
Technique. International Journal of Electrical and Computer
Engineering (IJECE), 6(2).
20. Ferdowsi, F., Edrington, C. S., & El-mezyani, T. (2015, October).
Real-time stability assessment utilizing non-linear time series
analysis. In North American Power Symposium (NAPS), 2015 (pp.
1-6). IEEE.
21. Ferdowsi, F., Yazdankhah, A. S., & Rohani, H. (2014, May). A
combinative method to control output power fluctuations of large
grid-connected photovoltaic systems. In Environment and Electrical
Engineering (EEEIC), 2014 14th International Conference on (pp.
260-264). IEEE.
22. Saberi, H., Sabahi, M., Sharifian, M. B., & Feyzi, M. (2014).
Improved sensorless direct torque control method using adaptive
flux observer. Power Electronics, IET, 7(7), 1675-1684.
23. Saberi, H., & Sharifian, M. B. B. (2012, October). An improved
direct torque control using fuzzy logic controllers and adaptive
observer. In Computer and Knowledge Engineering (ICCKE), 2012
2nd International eConference on (pp. 83-88). IEEE.
24. Saberi, H., Sharifian, M. B. B., & Amiri, M. (2012, May).
Performance improvement of direct torque control drives in low
speed region. In Electrical Engineering (ICEE), 2012 20th Iranian
Conference on (pp. 505-510). IEEE.
25. arXiv:1604.06691 [cs.SY]
26. Marzoughi, A., Imaneini, H., & Moeini, A. (2013). An optimal
selective harmonic mitigation technique for high power
converters. International Journal of Electrical Power & Energy
Systems, 49, 34-39.
27. Moeini, A., Iman-Eini, H., & Bakhshizadeh, M. (2014). Selective
harmonic mitigation-pulse-width modulation technique with variable
DC-link voltages in single and three-phase cascaded H-bridge
inverters. Power Electronics, IET,7(4), 924-932.
28. Hajinoroozi, Mehdi, et al. "Prediction of driver's drowsy and alert
states from EEG signals with deep learning" Computational
Advances in Multi-Sensor Adaptive Processing (CAMSAP), 2015
IEEE 6th International Workshop.
29. Hajinoroozi, Mehdi, et al. "Feature extraction with deep belief
networks for driver's cognitive states prediction from EEG
data." Signal and Information Processing (ChinaSIP), 2015 IEEE
China Summit and International Conference on. IEEE, 2015.
30. Grigoryan, Artyom M., and Mehdi Hajinoroozi. "Image and audio
signal filtration with discrete Heap transforms." Applied
Mathematics and Sciences: An International Journal (MathSJ) 1.1
(2014): 1-18.
International Journal of Soft Computing and Engineering (IJSCE)
ISSN: 2231-2307, Volume-6 Issue-2, May 2016
37
Published By:
Blue Eyes Intelligence Engineering
& Sciences Publication Pvt. Ltd.
31. Grigoryan, Artyom M., and Mehdi Hajinoroozi. "A novel method of
filtration by the discrete heap transforms." IS&T/SPIE Electronic
Imaging. International Society for Optics and Photonics, 2014.
32. Jenkinson, J., Grigoryan, A., Hajinoroozi, M., Diaz Hernandez, R.,
Peregrina Barreto, H., Ortiz Esquivel, A., ... & Chavushyan, V.
(2014, October). Machine learning and image processing in
astronomy with sparse data sets. In Systems, Man and Cybernetics
(SMC), 2014 IEEE International Conference on (pp. 200-203).
IEEE.
33. M. Najjar; A. Moeini; M. K. Bakhshizadeh; F. Blaabjerg; S.
Farhangi, "Optimal Selective Harmonic Mitigation Technique on
Variable DC Link Cascaded H-Bridge Converter to Meet Power
Quality Standards," in IEEE Journal of Emerging and Selected
Topics in Power Electronics , vol.PP, no.99, pp.1-1
34. Rakhshan, M., Vafamand, N., Shasadeghi, M., Dabbaghjamanesh,
M., & Moeini, A. (2016). Design of networked polynomial control
systems with random delays: sum of squares approach. International
Journal of Automation and Control, 10(1), 73-86.
... This paper employs the FC Inverter (FCI) in the three-phase TLPV grid-connected systems, as shown in Fig. 1, where an LCL filter is connected to the DC-link midpoint. A DC/DC Boost converter can be added between DC link and PV array [39]. This configuration offers reduced leakage current, improved output current quality and efficiency, and lowered DC-link capacitor ripples. ...
Article
Full-text available
In this paper, a Filter-Clamped (FC) inverter is employed as a three-phase grid-connected Transformerless Photovoltaic (TLPV) inverter. TLPV inverters are more efficient and more cost-effective compared to the alternatives based on high and low-frequency isolation transformers. On the other hand, TLPV inverters generate high leakage current due to the removal of the isolation transformer. Prior-art TLPV topologies have been developed to overcome this issue by either adding more semiconductor switches to block potential leakage current paths or modifying the control method. In contrast, the FC inverter addresses the leakage current issue without adding any extra component or improving the control technique. Thus, it is a promising solution to TLPV systems. Having decreased the leakage current, the FC inverter improves the THD of grid injected current and the efficiency compared to the conventional three-phase Full-Bridge (FB) inverter. Simulations and experiments are provided to validate the effectiveness of the FC inverter in terms of reduced leakage current, improved grid current THD, and improved overall efficiency.
... In that case, the boost converter is employed in the MPPT converter. There are many modifications and much research that was proposed by researchers to enhance the performance of the boost converters ( Figure 5) [41][42][43]. ...
Article
Renewable Energy Sources (RES) showed enormous growth in the last few years. In comparison with the other RES, solar power has become the most feasible source because of its unique properties such as clean, noiseless, eco-friendly nature, etc. During the extraction of electric power, the DC-DC converters were given the prominent interest because of their extensive use in various applications. Photovoltaic (PV) systems generally suffer from less energy conversion efficiency along with improper stability and intermittent properties. Hence, there is a necessity of the Maximum power point tracking (MPPT) algorithm to ensure the maximum power available that can be harnessed from the solar PV. In this paper, the most important features of the DC/DC converters along with the MPPT techniques are reviewed and analyzed. A detailed comprehensive analysis is made on different converter topologies of both non-isolated and isolated DC/DC converters. Then, the modulation strategies, comparative performance evaluation are addressed systematically. At the end, recent advances and future trends are described briefly and considered for the next-generation converter's design and applications. This review work will provide a useful structure and reference point on the DC/DC converters for researchers and designers working in the field of solar PV applications.
... In addition to forecasting, error has been also calculated to testify forecasting accuracy [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In the same way, the evaluation of model fit with the mean absolute deviation and mean square error which are two of the most popular goodness-of-fit have been considered. ...
... V. COMBINED MODEL Many new models are a combination of two or more different models [36][37][38][39][40][41][42][43][44][45][46][47][48][49]. As discussed before, extractive approaches are not favorable due to their lack of rearranging and rephrasing ability. ...
Article
Full-text available
This paper tries to employ a fuzzy logic (FL) controller type II to control the Cascaded H-Bridge (CHB) active rectifier. This controller has strong performance, specially, when a low switching frequency Selective Harmonic Elimination (SHE) method is used. In order to regulate all of the DC link voltages, the optimum voltage balancing strategy in the low frequency modulation technique is used in the proposed method. Finally, the performance and effectiveness of the proposed method is validated in MATLAB environment. All the simulation and result has been simulated by MATLAB software.
Conference Paper
Full-text available
This study considers the prediction of driver's cognitive states from electroencephalographic (EEG) data. Extracting EEG features correlated with driver's cognitive states is key for achieving accurate prediction. However, high dimensionality and temporal-and-spatial correlations of EEG data make extraction of effective features difficult. This study explores the approaches based on deep belief networks (DBN) for feature extraction and dimension reduction. Experimental results of this study showed that DBN applied to channel epochs (DBN-C) produces the most discriminant features and the best classification performance is achieved when DBN-C is applied to the time-frequency and independent-component-analysis transformed EEG data. The results suggested that DBN-C is a promising new method for extracting complex, discriminant features for EEG-based brain computer interfaces.
Conference Paper
Full-text available
Automated classification systems have allowed for the rapid development of digital large sky surveys. Such systems increase the independence of human intervention in the analysis stage of star and galaxy classification. Artificial neural networks, hierarchical classifiers and ensembles of classifiers have been used as the methods of classification in these systems. This paper investigates the development of an automated classification system for galaxies in astronomical images based on the method of sparse representation. The dependency of classification based on image enhancement by the alpha-rooting, heap-, and paired-transforms is secondarily investigated.
Article
Full-text available
There are different modulation techniques that can be used in medium-voltage and high-power electronic converters, but a few of them provide high efficiency and satisfy power quality requirements. This study presents a modified selective harmonic mitigation pulse-width modulation (SHM-PWM) technique which employs variable DC-link voltages as a degree of freedom in cascaded H-bridge (CHB) inverters. This degree of freedom increases the range of acceptable modulation indices, reduces the number of switching transitions and increases the number of harmonics that can be removed in selective harmonic elimination (SHE) (or SHM) techniques. Hence, in addition to efficiency improvement, a huge number of harmonics can be mitigated in AC side of the converter. Using this approach, triplen harmonics can be restricted to standard limits, in single-phase inverters. In addition, the proposed SHM-PWM approach employs the least number of switching transitions in a fundamental period to limit the specific number of harmonics compared to the alternative SHE or SHM techniques. In this study, the requirements of two well-known grid codes EN 50160 and CIGRE WG 36-05 are well satisfied and the validity of proposed method is verified by several simulations and experiments on a seven-level CHB inverter in single-phase and three-phase operating modes.
Article
In this paper, power quality standards such as IEC 61000-3-6, IEC 61000-2-12, EN 50160, and CIGRE WG 36-05 are fulfilled for single- and three-phase medium-voltage applications using selective harmonic mitigation-pulsewidth modulation in a cascaded H-bridge (CHB) converter. Furthermore, the ER G5/4 power quality standard, which has the strictest grid codes at the medium-voltage level, will also be met in the whole range of the modulation indices. In order to achieve this goal, a symmetrical CHB with variable dc links are employed, while the converter has a low number of switching transitions. In other words, all of the dc link voltages have the same voltage, which is dependent on the modulation index. Finally, in order to validate the effectiveness and the applicability of the proposed method, it is verified by simulations and experiments for a seven-level CHB converter.
Article
This paper tries to employ a fuzzy logic (FL) controller type II to control the Cascaded H-Bridge (CHB) active rectifier. This controller has strong performance, specially, when a low switching frequency Selective Harmonic Elimination (SHE) method is used. In order to regulate all of the DC link voltages, the optimum voltage balancing strategy in the low frequency modulation technique is used in the proposed method. Finally, the performance and effectiveness of the proposed method is validated in MATLAB environment. All the simulation and result has been simulated by MATLAB software.
Article
This paper studies the problem of networked polynomial state feedback control using the sum of square (SOS) approach considering network-induced varying delay. The stabilization conditions are achieved based on the Lyapunov-Krasovskii stability theory. The proposed control approach is based on the SOS decomposition numerical method which applies a control input to stabilize the networked control system states. Finally, numerical simulation is done to demonstrate the effectiveness of the proposed method.
Conference Paper
We investigate in this paper deep learning (DL) solutions for prediction of driver's cognitive states (drowsy or alert) using EEG data. We discussed the novel channel-wise convolutional neural network (CCNN) and CCNN-R which is a CCNN variation that uses Restricted Boltzmann Machine in order to replace the convolutional filter. We also consider bagging classifiers based on DL hidden units as an alternative to the conventional DL solutions. To test the performance of the proposed methods, a large EEG dataset from 3 studies of driver's fatigue that includes 70 sessions from 37 subjects is assembled. All proposed methods are tested on both raw EEG and Independent Component Analysis (ICA)-transformed data for cross-session predictions. The results show that CCNN and CCNN-R outperform deep neural networks (DNN) and convolutional neural networks (CNN) as well as other non-DL algorithms and DL with raw EEG inputs achieves better performance than ICA features.
Article
An interleaved current-fed full bridge DC/DC converter is proposed in this paper which shows good electrical compatibility to fuel cells inherent characteristics. By interleaving two isolated current-fed full bridge converters with parallel input and series output connection, input current ripple can be further reduced. In addition the size of the magnetizing components and current stress of the semiconductor devices on the input side are also reduced. Similarly, smaller voltage rating components can be used on the output side. Only one DSP board is used to generate phase-shifted gated signals and to implement a digital current controller. The main features of the proposed converter are high efficiency, small passive component size and small input current ripple. Experiment results for a 1.2kW interleaved current-fed full bridge converter are provided in the paper.
Conference Paper
Simple structure, quick, and robust response of direct torque control (DTC) make it attractive in ac drives. However, in sensorless applications, precise estimation of rotor speed is a crucial issue as well as the torque and flux estimation. In this paper an adaptive flux observer is introduced with stator current and flux vector components as state variables and rotor speed as an unknown parameter which are estimated simultaneously using an adaptive scheme. Also torque, flux, and current pulsations during steady state are considered as the disadvantages of the classical DTC method. A combined DTC-SVM strategy is presented using fuzzy logic control (FLC). Fuzzy logic controllers are designed such that obtain a fast response for dynamic performance, and high accuracy in steady state.