International Journal of Conceptions on Electrical and Electronics Engineering
Vol. 2, Issue. 1, April 2014; ISSN: 2345 - 9603
Design of DC-DC converter based on CUK topology
for PV system
Chirag Patel and Prof. H N Prajapati
Electrical Engineering Department
L.D.R.P. – I.T.R.
Gandhinagar, India.
chirag3.31891@yahoo.in and profprajapati@hotmail.com
Abstract— Photovoltaic power systems are becoming increasingly
prevalent in distribution and generation systems. Many nations
are installing significant solar power capacity in their grids as a
supplement or alternative to other power sources. This project
presents PV module with CUK converter for electrical
applications especially for dc load application. In this paper the
cuk converter and PV system is simulated AND hardware is
made for it and results are presented.
resistance), to minimize losses. When switch is turned on,
current flows from the input source through L1 and MOSFET,
storing energy in L1. Magnetic field. Then when MOSFET is
turned off, the voltage across L1 reverses to maintain current
flow.
Keywords- Solar PV module, Cuk converter, Matlab Simulink
I.
INTRODUCTION
A PV module is simulated and output is given to cuk
converter. A cuk converter proposed for analyzing the
performance of photovoltaic system is only for smooth
operation for dc output. In the proposed cuk converter, the
conduction losses and switching losses are reduced. The
switching techniques are to provide smooth transition of
voltage and current at input and output. So, the conversion
efficiency of the PV system is improved and the load meeting
the dynamic energy requirement is in an efficient way. It has an
advantage over other converting topologies since they enable
low voltage ripple on both the input and the output sides of the
converter. Then, the different operation mode of proposed cuk
converter is analyzed at different operating condition. The
proposed cuk converter implemented in MATLAB simulation
platform and the output performance is analyzed in this report.
The input and output result is shown in this project report. [11]
II. THE NON ISOLATED CUK CONVERTER
There are variations on the basic Cuk converter. For
example, the coils may share single magnetic core, which
drops the output ripple, and adds efficiency. Because the
power transfer flows continuously via the capacitor, this type
of switcher has minimized EMI radiation. [1] The Cuk
converter enables the energy flow bidirectionally, by adding a
diode and a switch. The basic circuit of a Cuk converter is
shown in Fig.1 and as you can see it has an additional inductor
and capacitor. The circuit configuration is in some ways like a
combination of the buck and boost converters, although like
the buck-boost circuit. It delivers an inverted output. Note that
virtually all of the output current must pass through C1, and as
ripple current. So C1 is usually a large electrolytic with a high
ripple current rating and low ESR (equivalent series
Figure1. BASIC CUK CONVERTER CIRCUIT
As in the boost converter current then flows from the input
source, through L1 and diode, charging up C1 to a voltage
somewhat higher than Vin and transferring to it some of the
energy that was stored in L1. Then when MOSFET is turned
on again, C1 discharges through via L2 into the load, with L2
and C2 acting as a smoothing filter. [7]
III.
= −
(
)
CONTINUOUS CONDUCTION MODE
In steady state, the energy stored in the inductors has to
remain the same at the beginning and at the end of a
commutation cycle. The energy in an inductor is given by:
E =
This implies that the current through the inductors has to
be the same at the beginning and the end of the commutation
cycle.
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VL = International Journal of Conceptions on Electrical and Electronics Engineering
Vol. 2, Issue. 1, April 2014; ISSN: 2345 - 9603
As the evolution of the current through an inductor is
related to the voltage across it:
It can be seen that the average value of the inductor
voltages over a commutation period have to be zero to satisfy
the steady-state requirements. If we consider that the
capacitors C and Co are large enough for the voltage ripple
across them to be negligible, the inductor voltages become
higher or lesser as describe below.
1. In the off-state, inductor L1 is connected in series
with Vi and C Therefore. As the L =
−
diode D is
forward biased (we consider zero voltage drop), L2 is directly
connected to the output capacitor. VL2 = Vo
2. In the on-state, inductor L1 is directly connected to
the input source. Therefore. 1 =
Inductor L2 is connected
in series with C and the output capacitor, so
+
2=
IV.
Figure 3. SIMULATION OF PV PANEL
SOLAR PHOTO VOLTAIC SYSTEM
Solar or photovoltaic (PV) cells are made up of materials that
turn sunlight into electricity. PV cells are composed of layers
of semiconductors such as silicon. Energy is created when
photons of light from the sun strike a solar cell and are
absorbed within the semiconductor material. This excites the
semiconductor’s electrons, causing the electrons to flow, and
creating a usable electric current. The current flows in one
direction and thus the electricity generated is termed direct
current (DC).
Figure 4. VOLTAGE AND CURRENT OF PV PANEL
Figure 2. PV PANEL
The shown panel is simulated in MATLAB and results are
taken. The above panel is also tested on different irradiation
of solar. For solar system the results are taking on 1000
This irradiation is according to standard. The open circuit
voltage and short circuit current was measured by standard
equipment. The simulation of PV panel in MATLAB is
shown
In figure 3 and the results of voltage and current on 1000
irradiation is shown in figure 4.
IRRADIATION
Voc
Isc
Vm
Im
1000
21.60V
2.27A
17.60V
2.05A
800
21.29V
1.81A
17.55V
1.61A
600
20.89V
1.36A
17.44V
1.19A
400
20.32V
0.98A
17.19V
0.76A
200
19.36V
0.45A
15.66V
0.35A
Solar panel is making with the help of thirty six cells in
series combination. The rating of solar panel is 12V and 30W.
The different results are presented here for different radiation
of sun light. The testing was made on testing machine which
make the test of solar panel on different radiation. The rating of
panel is decided on 1000
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radiation.
International Journal of Conceptions on Electrical and Electronics Engineering
Vol. 2, Issue. 1, April 2014; ISSN: 2345 - 9603
V.
OPEN LOOP SIMULATION OF CUK CONVERTER
The measurement devices connected in the basic circuit for
measure the different parameter of cuk converter operation.
This parameter remain constant for buck as well as in boost
operation of this converter. The switching frequency and
input voltage is same for buck operation and for boost
operation.
cycle. The variation is negligible and it is stable in less time
compare to other outputs. The ripple in output voltage and
current is very less and smooth which is good for any DC
load application.
Figure 7. OUTPUT CURRENT
The input power of cuk converter is 36.12W and output
power is 18.53W for buck operation of cuk converter. The
output power is approximately half of input power. By
changing its duty cycle we can regulate the power but the
optimum output of cuk converter is at 45% duty cycle.
Figure 5. THE SIMULATION CIRCUIT IN MATLAB
The input of cuk converter is the output of PV panel. Here
the pulse generator is use for Mosfet switching. The cuk
converter is give buck operation as well as boost operation.
VI.
VII. BOOST OPERATION OF CUK CONVERTER
The boost operation of cuk converter is achieved at higher
than 50% duty cycle. Here the result of 63% duty cycle is
presented for boost operation.
BUCK OPERATION OF CUK CONVERTER
The buck operation is taken for different duty cycle but
the best result is achieved at 45% duty cycle. Input
voltage is 21.60V here the switching frequency is 5kH
and the result is only for 45% duty cycle. The Output
voltage is -16.69V. The negative sign shows the inverted
output of cuk converter. Figure 6 shows the output voltage
waveform. Figure 7 is waveform of current for 45% duty
Figure 8. OUTPUT VOLTAGE FOR 63% DUTY CYCLE
Figure 6. OUTPUT VOLTAGE
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International Journal of Conceptions on Electrical and Electronics Engineering
Vol. 2, Issue. 1, April 2014; ISSN: 2345 - 9603
Figure 9. OUTPUT CURRENT FOR 63% DUTY CYCLE
The output voltage is -37.94V. Here the negative sign is for
inverted output of cuk converter. The output current for boost
operation is -2.52A. The output is very smooth and stable in
less time. It take less than 0.09sec for become stable. Input
power is 36.12W and output power is 95.60W for boost
operation of cuk converter.
VIII. HARDWARE OF CUK CONVERTER
DUTY
SWITCHING
INPUT
OUTPUT
VOLTAGE
FLUCTUATE
CYCLE
FREQUENCY
VOLTAGE
VOLTAGE
20%
5kHz
18.54 V
- 3.53 V
1.52%
45 %
5kHz
18.69 V
- 17.33 V
1.12%
63 %
5kHz
18.53 V
- 45.28 V
1.52%
65%
5kHz
18.51 V
- 53.56 V
1.67%
VIII. CONCLUSION
By performing the simulation of cuk converter it is
concluded on the basis of system performance that the output
of cuk converter is change with duty cycle. The buck and boost
operation is achieved in cuk converter by changing the duty
cycle. Cuk converter gives buck operation for less than 50%
duty cycle and gives boost operation for more than 50% duty
cycle. It is found by system performance that the best
performance of cuk converter is at 45% duty cycle for buck
operation and 63% duty cycle for boost operation. At this duty
cycle the output voltage regulation is minimum, the ripple in
output is very less and output is becomes stable in less time
compare to other outputs. The hardware result shows the best
result of cuk converter.
REFERENCES
[1]
R.sriranjani, A.Shree Bharathi, S.Jayalalitha, “Design of Cuk
converter Powered by PV array” 6(5):793-796, sept 2013
[2]
Neeraj Tiwan, D. Bhagwan Das(IJATER), “MPPT controller for
photo voltaic system using Cuk DC/DC converter” volume 2,
Issue3, 165-169,2012
[3]
Lekshmy Rajan U, R.Pradeep, “Performance Analysis of
Maximum Power Point Tracking based Photovoltaic Module
with Cuk Converter for Electrical Applications”. Volume 1,
issue 1, April 2013
[4]
M. manikanda prabhu, Dr. A. Manivanna “Modeling and
Performance Analysis of PV Panel Using Incremental
conductance Maximum Power Point Tracking” Volume 2, Issue
3, March, 2013
[5]
Cuk,S.: Coupled inductor and integrated magnetics techniques
in power electronics. Proceeding, of IECE, japan, 1983.pp. 347352
[6]
The table of hardware result is presented here and compare
with other duty cycles.
M.Vaigundamoorthi, R.Ramesh, “Experimental Investigation of
Chaos in Input Regulated Solar PV Powered Cuk Converter”
Volume 43– No.10, 0975 – 8887, April 2012
[7]
Here the voltage fluctuation is measured by DSO and
calculation for fluctuation is carried out. The buck and boost
operation of cuk converter is achieved but we got negative
output. The inverted output is basic property of cuk converter.
K.Kavitha*, Dr. Ebenezer Jeyakumar, “A Synchronous Cuk
Converter Based Photovoltaic Energy System Design and
Simulation” International Journal of Scientific and Research
Publications, Volume 2, Issue 10, October 2012
[8]
Electronics Handbook Devices, Circuits, And Applications
Third Edition By Muhammad H. Rashid, Ph.D.
Figure 9. HARDWARE OF CUK CONVERTER
The hardware of cuk converter is prepared for 30W system
and it is work properly and best output is achieved at 45%
duty cycle for buck operation. And for boost operation the
best result is achieved at 63% duty cycle.
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