Photovoltaic (PV) system is extensively increasing since it is clean, pollution free, and inexhaustible and by consider available resource as a future energy supply. The PV array output power is used to directly control the Pulse-width modulation (PWM), dc/dc boost converter, thereby reducing the complexity of the system. The resulting system has high efficiency with lower cost. This paper presents an improved Constant Coefficient of Short Circuit Current (CCSCC) Maximum Power Point Tracking (MPPT) technique under PWM control of photovoltaic (PV) power generation systems to obtain the maximum output power. The solar panel is modelled and analyzed in MATLAB/SIMULINK.

12. Ali Jasim, National Aerospace University “Kharkiv Aviation
Institute”, Postgraduate Student,
Yuri Shepetov, National Aerospace University “Kharkiv Aviation
Institute”, Associate Professor, Candidate of Science
An Intelligent Technique By Using The Method of Constant
Coefficient of Short Circuit Current Under Pulse Width
Modulation Control of The Photovoltaic Power System
Abstract: Photovoltaic (PV) system is extensively increasing since it is clean,
pollution free, and inexhaustible and by consider available resource as a future
energy supply. The PV array output power is used to directly control the Pulse-width
modulation (PWM), dc/dc boost converter, thereby reducing the complexity of the
system. The resulting system has high efficiency with lower cost. This paper presents
an improved Constant Coefficient of Short Circuit Current (CCSCC) Maximum Power
Point Tracking (MPPT) technique under PWM control of photovoltaic (PV) power
generation systems to obtain the maximum output power. The solar panel is
modelled and analyzed in MATLAB/SIMULINK.
Keywords: photovoltaic system, modeling of PV panels, Constant Coefficient
of Short Circuit Current, Boost converter and Simulation Results.
1. Introduction
The growing demand for electrical energy all over the world has caused a
great need to consider renewable energy sources as a technological option for
sustainable energy supply. Among the renewable energy sources photovoltaic (PV)
energy is now becoming one of the fastest growing renewable energy technologies
due to the continuous cost reduction and technological progress. PV is the field of
technology related to the application of solar cells by converting sunlight directly into
electricity.
Photovoltaic (PV) generation is becoming increasingly important as a
renewable source since it exhibits a great many merits such as cleanness, little
maintenance and no noise. Due to the nonlinear relationship between the current and
the voltage of the PV cell, it can be observed that there is a unique maximum power

13. point (MPP) at a particular environment, and this peak power point keeps changing
with solar illumination and ambient temperature.
An important consideration in achieving high efficiency in the PV power
generation system is to match the PV source and load impedance properly for any
weather conditions, thus obtaining maximum power generation. Therefore, the
system needs a maximum power point tracking (MPPT) which sets the system
working point to the optimum and increases the system’s output power. It is common
that the efficiency of a solar cell is very low. Some methods are used so as to match
the source and load properly, thereby increasing the efficiency of solar cell. This is
done by utilizing a boost converter whose duty cycle is varied by using an MPPT
algorithm.
Maximum power point tracker is an electronic DC to DC converter that
optimizes the match between the solar array (PV panels), and the load. The Power
point tracker is a high frequency DC to DC converter.
This paper introduces a new index, which designs an intelligent technique by
using the method of constant coefficient of short circuit current under pulse width
modulation control of the photovoltaic Power system [1-6]. The paper is organized in
the following way. Section two presents Nomenclature about everything related to
study. In section three presents the entire proposed PV system configuration which
components are used and also discuss about the mathematical modeling of the PV
array, Maximum Power Point Tracking, analyzing the boost converter. In section four
simulation results of numerical experiments under considerations are discussed.
Finally, conclusions are made in section five.
2. Nomenclature
PV – Photovoltaic.
Ipv=I – Output Panel current, (A).
Vpv=V – Output Panel voltage, (V).
Iph – Photovoltaic Current, (A).
Io – Reverse saturation current of the diode, (A).
Q – Electron charge (1.602 10-19
), (C).
Rs – Series resistance of the cell, ( ).
Rsh – Shunt Resistance of the cell, ( ).
KB – Boltzmann constant (1.38 10-23
), (J/K).
N – The diode factor.

14. ISC – Nominal Short-Circuit Current, (A).
VOC – Nominal Open Circuit Voltage, (A).
VT – Thermal Voltage (V).
IMP – Current at the maximum power point, (A).
VMP – Voltage at the maximum power point, (V).
KI – Constant coefficient of short circuit current.
G – Illumination, (W/m2
).
T – PV cell temperature, (K).
toff – On/off duty cycle of the switching controls.
PW – Relative pulse width (pulse ratio).
P – power generated by the PV array, (W).
Pout – Output power, (W).
PPV – Input power, (W).
D – Duty cycle.
Fcn1 – Represent the equation between ISC & G.
Fcn2 – Represent the equation between VOC & G.
D1,D2 – Diode1, Diode 2.
C – Capacter, (F).
VO – Output voltage of the DC-DC Boost Converter.
3. Proposed PV system
Figure 1 shows the proposed PV system which is single stage power conditioning
system, used for feeding the DC loads. The PV system consists of different elements
like solar PV array, short circuit current MPPT method, boost converter, energy
storage element and net load. Here the PV array is a combination of series and
parallel solar cells. This array develops the power from the solar energy directly and
it will be changed by depending upon the temperature and solar irradiances.
The DC-DC boost converter is controlled so as to track the maximum power point
of the PV array and to transfer the energy to the net load [3-5].

15. Figure 1. Block Diagram of Power Conditioning PV System
3.1. Mathematical Modeling of PV Array
The output obtained from the panel is variable DC voltage, this voltage
depends upon the solar radiation intensity and temperature. The simple equivalent
circuit of PV cells is shown in figure 2 [2-8].
From the circuit in figure (2) the output panel current can be expressed as Eq.
(1).
( )
( )
1
S
B
q V I R
NK T
p
s
h o
sh
I R
I eI
R
V
I
.
(1)
Figure 2. Equivalent Circuit of Photovoltaic Cell
Three operation points on the I-V curve are of special interest for
understanding solar cell operation and for designing photovoltaic systems:
Short Circuit Current MPPT Method
Boost
Converte
r
Net
Load
Id
Rs
Vpv
+
Ipv
-
Isc
(Iph )
Rsh
Ish

16. The short circuit point (I=ISC, V=0); the open circuit point (I=0, V=VOC) and the
maximum power point (I=IMP, V=VMP).
At the short circuit operation point (I=ISC, V=0) the solar cell model Eq. (1) Can
be rewritten as in Eq. (4), which allows to approximate the photo-generating
capabilities (Iph) of the solar cell with the short circuit current (ISC) under certain
conditions Eq. (2).
,SC ph s sh o phI for R R Iand II . (2)
From here we can infer the main factors influencing the voltage of the solar
cell are: the temperature through the thermal voltage (VT) as in Eq. (3), followed to a
lesser extent by the irradiance through (Iph).
T B
T
V = K
q
; (3)
(4)
The solar cell operation can be described at the open circuit (I=0, V=VOC) as in
Eq. (5), and assuming a high shunt resistance (Rsh), the solar cell open circuit voltage
(VOC) can be approximated as in Eq. (6).
(5)
(6)
The resistances Rs and Rsh are usually neglected in order to simplify the model
and under certain conditions Eq. (2) (ISC Iph) Therefore, Eq. (1) Can be simplified to
Eq. (7) [4-8].
(7)
Under an open circuit condition at the PV array can be expressed as Eq. (8).

17. (8)
The maximum power point (MPP) is may be the most important parameter relating
to PV system performance and operation.
At the maximum power point, where IMPP and VMPP are the Current and Voltage at
maximum-power point. From (7) and (8), regarding that exp(V/NVT)>1 under normal
operation of the diode, the following expressions can be approximated as Eq. (9).
(9)
The output voltage of the PV generator can be expressed as a function of the
output current, in terms of parameters such as VOC and ISC.
(10)
The maximum power point generated by the PV array can be expressed as Eq.
(11) and Eq. (12).
(11)
(12)
As initial data for Model there were used experimental data from solar panel
educational bench in school laboratory in National Airspace University «KhAI», the
Department of space technology and alternative energy sources with Si PV cell
manufactured by Siemens Corp [2-3]. The common structure of PV Panel Simulation
Model is represented in Figure 3.
Simulation of the I-V curve Fig.4a) & P-V curve Fig.4b) of PV module under
changing illumination are represented in Figure 4.

18. Figure 3. PV Panel Simulation Model
a) b)
Figure 4. Simulation of I-V curve a) & P-V curve b) of PV module under
changing illumination
3.2. MPPT Technique
There are different methods through which the maximum power point in the P-
V curve can be obtained. The I-V and P-V characteristics of a PV cell depend upon
the solar radiation intensity and temperature [2-5].
By controlling the parameters like current or voltage or both the pinnacle can
be obtained. Short Circuit Current (SCC). This method represents an indirect
approach, The short circuit current (ISC) technique is based on the measurement of
the PV module SCC when its output voltage is equal to zero, and the PV module
maximum output current at MPP (IMP), is linearly proportional to (ISC) [1-4]. In order to
match the two currents, the error current is used to regulate the duty ratio of DC-DC
Rsh
0.001736*u-0.057
Fcn1
Voc
s +-
-s
0.0105*u+13.675
Fcn 2
D2
Rs
C
D1
Isc
E
E
+VIN
Illumination
1
1
2
-VIN

19. converter and the relationship between the PV module output current and SCC at
MPP (IMP), which can be described by the following Eq. (13).
MPP I SCI k I . (13)
Where KI is a constant in the range 0.78-0.92, (KI <1) that can be calculated
from the PV curve [4-8]. The SCC flowchart is shown in Figure 5.
Figure 5. Flow chart of the (SCC) Method
This method has a disadvantage an undeveloped but a rapid technique of
tracking the MPP. To track the power, this MPPT technique requires the value of
SCC by isolating the PV array. The power output is not only reduced when finding
ISC but also because the MPP is never perfectly matched. A way of compensating KI
is proposed such that the MPP is better tracked while atmospheric conditions
change. The performance stages of the suggested technique are as follows. It
measures the Isc during the start of the MPP tracking. The value of short circuit
current is then converted numerically to maximum Power Point current using Eq. (13)
[1-4]. After calculating the duty cycle D, the controller reduces the error.
The duty cycle D is used to drive the DC-DC converter and is adopted as the
initial point of performance for the constant coefficient of short circuit current. The
constant coefficient current method starts tracking the real MPP with very small steps
after operating the DC-DC converter at approximated MPP. However, under varying
environmental conditions the limit helps the system to Fastly track the MPP [3-10].
Decrease Duty
Cycle
Increase Duty
Cycle
Update
Reference ?
PV short circuit
condition
Measurement
of SC
PV work
condition
IMP=KI SC
Measurement of IMP
IMP=Iref
IMP>Iref
No
Yes
No
Yes No
Yes

20. 3.3. Pulse Width Modulation (PWM)
Pulse width modulation (PWM) is a powerful technique for controlling analog
circuits with a processor's digital outputs. The PWM technique is used to control the
closing and opening switches. The switching scheme applied is unipolar. The PWM
signal is used to control ON/OFF switching state of the IGBTs (insulated-gate bipolar
transistor) will function in driver model that created to control the switching scheme.
The duty cycle of a square wave is modulated to encode a specific analog signal
level by using a higher resolution counter. The benefit of choosing the PWM over
analog control increases noise immunity, which the PWM is sometimes used for
communication [2, 4, 5, 10]. The system formation of the PWM is shown in figure 6a.
And the systematic formation of the Pulse generation is shown in figure 6b.
a) b)
Figure 6. Block Diagram of PWM a) and Pulse Generation b)
3.4. DC-DC Boost Converter
In DC-DC Boost converter output voltage (VO) is greater than the input voltage
(VPV) of boost Converter. Consider a boost type converter connected to a PV module
with a resistive load as illustrated in Figure 7.
This Figure shows a step up or the PWM boost converter. It consists of a DC
input voltage source Vpv; boost inductor L, controlled switch T, diode D, filter
capacitor C, and the load resistance RL.
Here at the circuit, we can be observed that when the switch S is in the on
state (close the switch S), the current in the boost inductor increases linearly and
energy is stored in inductor L and the diode D was off at that time of the output RC
circuit [3, 8, 9, 10].
When the switch S is in the off state (opens the switch S), the diode D was on
at that time the energy which was stored in the inductor is transferred to a resistive
Pulse Generator
D
Duty Cycle Gate
Switch (T)
Pulse Width Modulation
E
IGBT
+VIN 1
-VIN 2 Pulse generator
1
period
2*pi
1
Duty Cycle
+
-
integretor
sign
Rem(u(1),u(2))/2/pi
u1
u2
1- (Rem(u(1),u(2))/2/pi)
((Rem(u(1),u(2))/2/pi) +1)/2 1
Gate
1
s

21. load through diode D and at the same time inductor current will fall. The role of
capacitor in the circuit is for producing a continuous output voltage VO [10].
Figure 7. Circuit diagram of DC-DC boost converter
The power switch is responsible for modulating the energy transfer from the
input source to the load by varying the duty cycle D [2, 3, 6, 10].
The relation between output voltage and the input voltage (solar cell) is given
as the equation (14):
(14)
4. Simulation results
Output power of PV unit is strongly depended from the value of the Relative
Duty Cycle (D), and for each value of net voltage there is corresponded certain value
of PW which provides maximum output power (Fig 7a). With increasing of net voltage
the values of Duty Cycle (D) increase too. In the same manner for each value of
sunshine illumination there is corresponded certain value of Duty Cycle (D) which
provides maximum output power (Fig 7b). With increasing of illumination the optimal
Cycle (D) decreases.
Thus the task of control of studying the PV unit consists in finding for each
moment of optimal Cycle (D) which correspond to changeable external parameters
(illumination and net voltage) for providing maximum output power. The values of
optimal Cycle (D) are collected in Table 1.
There are also exist the losses of power due to dissipate energy under
transformation (Fig. 8a). They are more with Cycle (D) increasing. But all the same,
this loss is repaid through increasing of output power.
IL D
S C
Vo
VL
ID
L
Ic IR

22. a) b)
Fig. 7 Output power as function from PW for different net Voltage (a)
and different Illumination (b)
Voltage, Illumination, W/m2
V 600 700 800 900 1000
14 0.0001 0.0001 0.0001 0.0001 0.0001
15 0.0001 0.0001 0.0001 0.0001 0.0001
16 0.0001 0.0001 0.0001 0.0001 0.0001
17 0.0001 0.0001 0.0001 0.0001 0.0001
18 0.001 0.0001 0.0001 0.0001 0.0001
19 0.01 0.0001 0.0001 0.0001 0.0001
20 0.11 0.04 0.0001 0.0001 0.0001
21 0.18 0.09 0.001 0.0001 0.0001
22 0.19 0.15 0.05 0.001 0.0001
23 0.22 0.17 0.09 0.05 0.01
24 0.26 0.18 0.12 0.09 0.06
25 0.28 0.19 0.15 0.12 0.09
26 0.29 0.24 0.19 0.16 0.12
27 0.3 0.25 0.21 0.2 0.17
28 0.32 0.28 0.24 0.22 0.19
29 0.34 0.3 0.28 0.24 0.21
30 0.37 0.33 0.3 0.27 0.24
Table 1. Values of optimal Duty Cycle (D) provided maximum output power
0 0,1 0,2 0,3 0,4 0,5
Pulse Width
14 V
16 V
18 V
20 V
22 V
24 V
Illumination –
800 W/m2
0
2
4
6
8
10
12
14
16
18
20
0 0,1 0,2 0,3 0,4 0,5
Pulse Width
Output Voltage
– 17 V
600 650 700
750 800 850
900 950
Illumination, W/m2
1000
0
5
10
15
20
25

23. Regulator transformation efficiency is shown in (Fig. 8b). It was calculated as
the ratio between output and input power for certain external conditions.
a) b)
Fig. 8 Input/Output power of regulator (a) and relationship between them (b)
The integrated 3D relationship of optimal Duty Cycle from illumination and net
voltage is shown in (Fig. 9a).
The integrated 3D relationship of maximum output power (under optimal D)
from illumination and net voltage is shown in (Fig. 9b).
a) b)
Figure 9. 3D relationship of MP Duty Cycle a) and MP from illumination
and net voltage b)
0
5
10
15
20
25
30
35
0 0, 05 0,1 0, 15 0,2 0, 25 0,3 0, 35 0,4 0, 45
Ppv
Pout
Illumination– 1000 W/
2
Net voltage – 21V
m
Duty Cycle
0,82
0,84
0,86
0,88
0,9
0,92
0,94
0,96
0,98
0 0,1 0,2 0,3 0,4 0,5 0,6
0
Illumination– 1000 W/
2
Net voltage – 21 V
m
Duty Cycle
0
5
10
15
20
25
30
35
40
45

24. Conclusion
This study presents an energy-efficient, fast-tracking MPPT circuit PV energy
reaper. Firstly, it presents the characteristics of the PV system and mathematical
model. The maximum power point tracking (MPPT) strategy based on the constant
coefficient of the short circuit current method is proposed. The results gained from
simulation employing short circuit current approach display the effectiveness of the
proposed power tracking and control strategies with quick power tracking response
and well direct current output.
However, by using this MPPT method we have increased efficiency. This
method computes the maximum power and controls directly the extracted power from
the PV. The proposed method offers different advantages which are: good tracking
efficiency, response well high and controls for the extracted power.
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