International Journal of Multidisciplinary Approach and Studies ISSN NO:: 2348 – 537X Volume 02, No.4, July-August, 2015 Page : 75 Interleaved Boost Converter for PV Cell Application Using DSPIC Mr.V.Srimaheswaran*, Mr.V.J.Sivanagappa**and Mr. B. Goutham*** *Assisant Professor, Department of EEE, Vivekanandha College of Engineering for Women, Tiruchegode **Assisant Professor, Department of EEE, Anjalai Ammal Mahalingam Engineering College, Kovilvenni ***Assisant Professor, Department of EEE, Vivekanandha College of Engineering for Women, Tiruchengode ABSTRACT: The PV power generation have low efficiency due to the various constrain, to utilize the maximum power generated by the solar panel, it is required to match its internal resistance with that of the load. This thesis gives a new proposed method to improve the performance of the PV system. The PV cell is connected to the battery, interleaved boost converter. Battery can be used as a backup power source when the photovoltaic system is incapable of supplying power to the load. The proposed resonant circuit based interleaved boost converter is to achieve high output voltage. A PWM technique is used to generate the PWM signal for interleaved Boost switches. The purpose of boost converter is to step up the voltage. The simulation results are validated for different duty cycle. The hardware is implemented with the PV cell, battery, interleaved boost converter and DSPIC microcontroller. The DSPIC microcontroller is used to generate the PWM signals for boost converter switches. The output voltage of interleaved boost converter is given to the load. This topology increases the performance of the dc to dc converter and reduces the ripples. The result obtained through the simulation is verified with the hardware. Key words — PV Array, Interleaved Boost Converter(IBC). 1. INTRODUCTION DC-DC converters play an important role in interfacing the non-conventional energy sources like photovoltaic current to useful DC or AC form. It is therefore necessary that the interfacing converter should be highly efficient in transferring the power to ensure proper load management. The boost topology is the most popular topology for getting constant value of high DC output [14] as it’s simple power circuit leads to high efficiency and high reliability at low cost. In case of hard switching boost converters, due to overlapping of voltage and current waveforms during switching and the reverse recovery of the diode with each switching cycle, there is a high amount of switching loss associated with it. In order to address these shortcomings, new power electronics circuits are designed based on resonant and soft- switching technologies [11].
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International Journal of Multidisciplinary Approach
and Studies ISSN NO:: 2348 – 537X
Volume 02, No.4, July-August, 2015
Pag
e : 7
5
Interleaved Boost Converter for PV Cell Application Using
DSPIC
Mr.V.Srimaheswaran*, Mr.V.J.Sivanagappa**and
Mr. B. Goutham***
*Assisant Professor, Department of EEE, Vivekanandha College of Engineering for Women, Tiruchegode
**Assisant Professor, Department of EEE, Anjalai Ammal Mahalingam Engineering College, Kovilvenni
***Assisant Professor, Department of EEE, Vivekanandha College of Engineering for Women,
Tiruchengode
ABSTRACT:
The PV power generation have low efficiency due to the various constrain, to utilize the
maximum power generated by the solar panel, it is required to match its internal resistance
with that of the load. This thesis gives a new proposed method to improve the performance of
the PV system. The PV cell is connected to the battery, interleaved boost converter. Battery
can be used as a backup power source when the photovoltaic system is incapable of
supplying power to the load. The proposed resonant circuit based interleaved boost converter
is to achieve high output voltage. A PWM technique is used to generate the PWM signal for
interleaved Boost switches. The purpose of boost converter is to step up the voltage. The
simulation results are validated for different duty cycle. The hardware is implemented with
the PV cell, battery, interleaved boost converter and DSPIC microcontroller. The DSPIC
microcontroller is used to generate the PWM signals for boost converter switches. The output
voltage of interleaved boost converter is given to the load. This topology increases the
performance of the dc to dc converter and reduces the ripples. The result obtained through
the simulation is verified with the hardware.
Key words — PV Array, Interleaved Boost Converter(IBC).
1. INTRODUCTION
DC-DC converters play an important role in interfacing the non-conventional energy sources
like photovoltaic current to useful DC or AC form. It is therefore necessary that the
interfacing converter should be highly efficient in transferring the power to ensure proper
load management. The boost topology is the most popular topology for getting constant value
of high DC output [14] as it’s simple power circuit leads to high efficiency and high
reliability at low cost.
In case of hard switching boost converters, due to overlapping of voltage and current
waveforms during switching and the reverse recovery of the diode with each switching cycle,
there is a high amount of switching loss associated with it. In order to address these
shortcomings, new power electronics circuits are designed based on resonant and soft-
switching technologies [11].
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In these cases, an increase in the efficiency of the system is accounted for, owing to non-
overlapping of the voltage and current waveforms during switching. This results in decreased
output ripple at higher values of frequencies [7]. Also, with an increase in frequency, it is
possible to use smaller values of inductors and capacitors, which results in the reduction of
the sizes of the components and thus increasing the power density [11]. However, the major
challenge still remains as the design of the converter, especially when the constraints such as
permissible stresses and conduction losses are stringent.
An interleaved boost converter usually combines more than two conventional topologies,
and the current in the element of the interleaved boost converter is half of the conventional
topology in the same power condition. Besides, the input current ripple and output voltage
ripple of the interleaved boost converter are lower than those of the conventional topologies.
The demand for renewable energy has increased significantly over the years because of
shortage of fossil fuels and greenhouse effect. Among various types of renewable energy
sources, solar energy and wind energy have become very popular and demanding due to
advancement in power electronics techniques. Photo-Voltaic (PV) sources are used today in
many applications as they have the advantages of being maintenance and pollution free.
Solar-electric-energy demand has grown consistently by 20%–25% per annum over the past
20 years, which is mainly due to the decreasing costs and prices. This decline has been driven
by the following factors: 1) an increasing efficiency of solar cells 2) manufacturing
technology improvements and 3) economics of scale [9].
2. MODELING OF THE SOLAR CELL
Thus the simplest equivalent circuit of a solar cell is a current in parallel with a diode. The
output of the current source is directly proportional to the light falling on the cell. During
darkness, the solar cell is not an active device; it works as a diode, i.e. a P-N junction. It
produces neither a current nor a voltage. However, if it is connected to an external supply
(large voltage) it generates a current Id, called diode current or dark current. The diode
determines the V-I characteristics of the cell.
Fig. 1. Equivalent Circuit of a Solar Cell
Fig. 1 shows the equivalent circuit of a solar cell, where, RS is the very small series
resistance and Rsh is the quite large shunt resistance. Dj is the ideal P-N diode, Iph expresses
as the photocurrent source generated proportionally by the surface temperature and
insolation. V and I represent the output voltage and output current of the solar cell,
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respectively. According to the physical property of the P-N semiconductor, the I-V
characteristics of PV module could be expressed.
(1)
In addition, the modules reverse saturation current Isat.
(2)
The Iph is expressed in (3) represents the photocurrent proportionally produced to the level of
cell surface temperature and radiation, where ISSO is the short-circuit current, Ki is the short-
circuit current temperature coefficient, and Si is the solar radiation in W/m2 [8].
(3)
2.1 V-I CHARACTERISTICS of PV CELL
Each solar cell has its own voltage-current (V-I) characteristic. Fig. 2 shows the V-I &
P-V characteristic of a typical photovoltaic cell. The problem with extracting the most
possible power from a solar panel is due to nonlinearity of the characteristic curve. The
characteristic shows two curves, one shows the behavior of the current with respect to
increasing voltage. The other curve is the power-voltage curve and is obtained by the
equation (P=I*V).
Fig. 2. Solar Panel V-I Characteristic and Power Curve
When the P-V curve of the module is observed, one can locate single maxima of power
where the solar panel operates at its optimum. In other words, there is a peak power that
corresponds to a particular voltage and current. Obtaining this peak power requires the solar
panel to be operated at or very near the point where the P-V curve is at the maximum [8].
3. INTERLEAVED BOOST CONVERTER
The interleaved boost converter will represent one of the most significant portions to get
maximum output. Ideally, the maximum power will be taken from the solar panels. In order
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to do so, the panels must operate at their optimum power point. The output of the solar panel
will be either shorted or open circuited through the opening or closing of a switch.
A basic boost converter converts a DC voltage to a higher DC voltage. Interleaving adds
additional benefits such as reduced ripple currents in both the input and output circuits.
Higher efficiency is realized by splitting the output current into two paths, substantially
reducing I2R losses and inductor AC losses. This advantages of interleaving, such as higher
efficiency and reduced input and output ripple, are also realized in the boost topology. Most
of the controllers used in these applications apply equally well when configured for use in an
interleaved boost application. As power densities continue to rise, interleaved boost designs
become a powerful tool to keep input currents manageable and increase efficiency, while still
maintaining good power density. With mandates on energy savings more common,
interleaved construction may be the only way to achieve design objectives.
The concept of interleaving, or more generally that of increasing the effective pulse
frequency of any periodic power source by synchronizing several smaller sources and
operating them with relative phase shifts, is not new. Interleaving technique actually exists in
different areas of modern technologies in different forms..In the field of power electronics,
application of interleaving technique can be traced back to very early days, especially in high
power applications. In high power applications, the voltage and current stress can easily go
beyond the range that one power device can handle. Multiple power devices connected in
parallel and/or series could be one solution. However, voltage sharing and/or current sharing
are still the concerns. Instead of paralleling power devices, paralleling power converters is
another solution which could be more beneficial. Furthermore, with the power converter
paralleling architecture, interleaving technique comes naturally. Benefits like harmonic
cancellation, better efficiency, better thermal performance, and high power density can be
obtained. In earlier days, for high power applications, in order to meet certain system
requirement, interleaving multi-channel converter could be a superior solution especially
considering the available power devices with limited performance at that time. One of such
example can be found in the application of Superconducting a Magnetic Energy Storage
System (SMES).The current stress of such application is extremely high, yet certain system
performance still need to be met.
3.1 OPERATION
Recently, high-performance dc–dc converters have been called for the increasing high step-
down ratios with high output current rating applications, such as VRMs of CPU boards and
battery chargers, and distributed power systems. For non isolation applications with low
output current ripple requirement, an interleaved boost converter (IBC) has received a lot of
attention due to its simple structure and low control complexity.
Here input is low voltage dc supply has been given and high voltage dc supply is derived.
Such as in between inversion, high frequency transformation & voltage doubler operation are
carried on.
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Low voltage dc supply is given to single phase inverter. In this topology the single phase
inverter as inductor (L1). Thereby by switching the two switches for positive half cycle &
another two switches for negative half cycle. Thus during shoot through state of two
switching sequence the inductor connected will be charged and it will be discharged during
negative half cycle. Because of this boosted ac voltage is acquired across the single phase
inverter.
Across the single phase inverter we are also used LC filter to remove the ripple free output at
the end of single phase inverter and we are using a special high frequency transformer for
switching that boosted ac signal at high frequency state.
Fig. 3. Circuit Diagram of Interleaved Boost Converter
Here by getting that high frequency boosted ac signal; the six stage three level voltage
doubler will derive the dc output level upto six times from the given high frequency boosted
ac signal. As we are using mur diodes and high power rated capacitors the output voltage and
power will be much higher than the normal dc-dc converter.
3.2 ADVANTAGES
High voltage gain
Reduces the voltage stress of both active switches and diodes
Conduction loss is less
Used for higher power ratings at high voltage ratings.
Easy control method is employed for switching devices without complex circuits.
4. SIMULATION MODEL & RESULTS
Proteus Professional-software for automated design of electronic circuits. The package is a
system of circuit simulation, based on the models of electronic components in PSPICE. A
distinctive feature of the package Proteus Professional is the possibility of modeling of the
programmable devices: microcontrollers, microprocessors, DSP and others. Additionally, the
package of Proteus Professional is a system design of printed circuit boards. Proteus
Professional can simulate the following microcontrollers: 8051, ARM7, AVR, PIC. In this
project, interleaved boost converter for PV application is modeled using Proteus7.7 software.
The simulated result is discussed with the switching pulse; input voltage and output voltage
are analyzed.
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Fig. 4. Simulation Model of Interleaved Boost Converter
4.1 SIMULATION RESULT FOR 25% DUTY CYCLE
Fig. 5. Switching Pulses for Boost Convverter
Fig 5 shows the switching pulses for interleaved boost converter that are generated using
single pulse width modulation. The pulse is given to the MOSFET switch is turned on at a
correct sequence to obtain the output.
Fig. 6. Input and Output Waveforms of High Frequency Transformer
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Fig 6 shows the input and output waveforms of high frequency transformer. The transformer
primary and secondary voltages are 3.7V and 37V (Peak – Peak). The output of transformer
is given to the six stage three level voltage doublers rectifier.
Fig.7. Input and Output waveform of Interleaved Boost Converter
Fig 7 shows the input and output waveform of interleaved boost converter. Channel B
and Channel C is connected to the input and output. The input has the voltage of 12V.The
output voltage has pulse which occurs due to the grounding. In order to show the value of the
DC output voltage it has been grounded. Here we have obtained 4 quadrant of 105V.
4.2 SIMULATION RESULT FOR 50% DUTY CYCLE
Fig. 8. Switching Pulses for Boost Converter
Fig 8 shows the switching pulses for interleaved boost converter that are generated using
single pulse width modulation. The pulse is given to the MOSFET switch is turned on at a
correct sequence to obtain the output.
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Fig. 9. Input and Output Waveforms of High Frequency Transformer
Fig 9 shows the input and output waveforms of high frequency transformer. The transformer
primary and secondary voltages are 7.2V and 72V (Peak - Peak). The output of transformer is
given to the six stage three level voltage doubler rectifier.
Fig.10. Input and Output waveform of Interleaved Boost Converter
Fig 10 shows the input and output waveform of interleaved boost converter. Channel B and
Channel C is connected to the input and output. The input has the voltage of 12V.The output
voltage has pulse which occurs due to the grounding. In order to show the value of the DC
output voltage it has been grounded. Here we have obtained 4 quadrant of 196V.
5. EXPERIMENTAL ANALYSIS
The hardware of Solar panel with Interleaved Boost converter is implemented and the output
is fed to the load. The DC supply from the battery is given to the interleaved boost converter.
The boosted voltage is then given to the load. The microcontroller is used to produce control
signals based on pulse width modulation technique for the gates of the MOSFET. The
hardware results are input voltage, gate pulses, input voltage of transformer and output
voltage of converter. These result measured using Digital Storage Oscilloscope (DSO).
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Fig. 11. Hardware Circuit for Interleaved Boost Converter
Fig 11 shows the hardware circuit for interleaved boost converter. The gate pulses for
interleaved boost converter are generated using PIC microcontroller.
Fig.12 Input Voltage Waveform
Fig 12 shows the input voltage of 9V which is obtained from the solar panel is then given to
the interleaved boost converter.
Fig. 13. Switching Pulse for Interleaved Boost Chopper
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Fig 13 shows the switching pulses for interleaved boost converter. The switching pulses are
generated using DSPIC microcontroller and are given to the switches. The pulses supplied
from the DSPIC have the amplitude of 5V which is not enough to drive the MOSFET
switches and therefore optocoupler IC’s are employed to regulate the voltage. The switches
S1, S2, S3 and S4 are turned on at a correct sequence.
Fig. 14. High Frequency Transformer Input Voltage Waveform
Fig 14 shows the transformer pulsating input voltage waveform of 80V (Peak - Peak) which
is given to the voltage doublers rectifier circuit.
Fig. 15. Output Voltage for Interleaved Boost Converter
Fig 15 shows the interleaved boost converter output voltage of 240V. The input 9V is boosted
to 240V.
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Fig. 16. Expérimental Set up
6. CONCLUSION
This Project gives the clear idea about the interleaved boost converter topology for PV cell.
The voltage level is improved by using the interleaved boost chopper. The proposed method
adds additional benefits such as reduced ripple currents in both the input and output circuits.
The circuit topology and the operational principle of the proposed converter are analyzed in
detail. The simulation results are validated for the different duty cycle. The hardware is
implemented with Solar panel, interleaved boost converter and DSPIC microcontroller. Boost
converter can be used to step up the voltage. The pulses are generated and it is given to the
switches by using pulse width modulation technique (PWM). Simulation and experimental
results shows the proposed interleaved converter topology structure. The results obtained
through the simulation are verified by using the hardware.
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iii. Jee-Hoon Jung, and S. Ahmed, “Model Construction of Single Crystalline
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v. S.H. Park, G.R. Cha, Y.C. Jung and C.Y. Won, “Design and application for PV
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