Photovoltaic array fed inverter

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 05 | May-2014, Available @ http://www.ijret.org 257
PHOTOVOLTAIC ARRAY FED INVERTER
Babu Paul1
, Sarath M S2
, Sebastian Jo Thalackal3
, Sharun Vittappan4
, Shonitha Krishnan M5
1
Assistant professor, Dept. of EEE, Mar Athanasius College of Engineering, Kothamangalam, Kerala, India
2
U G students, Dept. of EEE, Mar Athanasius College of Engineering, Kothamangalam, Kerala, India
3
4
5
Abstract
Solar energy is the most low cost, competition free, universal source of energy as sun shines throughout. This energy can be converted
into useful electrical energy using photovoltaic technology. The steady state reduction of price per peak watt and simplicity with
which the installed power can be increased by adding panels are attractive features of pv technology. In this project, a controller to
vary the amplitude of the inverter output voltage interposed between the PV array and the load is developed. The detailed modelling
of the components of proposed scheme has been taken up. The developed controller varies the pulse-width of a PWM generator, so
that that the inverter output voltage varies with irradiation and temperature. The variation of the amplitude is to maximize the power
output for a given radiation and temperature. Experimental investigation presented gives the utility of such a control approach.
Keywords: PV Array, Inverter, PIC16F616 microcontroller, PWM technique
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1. INTRODUCTION
As the sources of conventional energy are deteriorating fastly
with a corresponding rise in cost, considerable attention is
being paid to other alternative energy sources. It is well known
that non-conventional energy sources are friendly to the
environment, sustainable and are attractive alternatives in
places where a connection to the utility network is either
impossible or unduly expensive. Hence, there is an increasing
interest in standalone generating systems based on renewable
energy. Among them, solar energy which is free and abundant
in most parts of the world has proven to be a challenging
source of energy in many developing and developed countries.
Photovoltaic’s (PVs) are arrays (combination of cells) that
contain a solar voltaic material that converts solar energy into
electrical energy. PV cell is a basic device for Photovoltaic
Systems. Such systems include multiple components like
mechanical and electrical connections and mountings and
various means of regulating and (if required) modifying the
electrical output. Materials that are used for photovoltaic are
mono-crystalline silicon, polycrystalline silicon,
microcrystalline silicon, cadmium telluride and copper indium
selenide. The current and voltage available at the PV device
terminals can be directly used to feed small loads like lighting
systems or small DC motors. In order to get constant power
output from PV array we have to model photovoltaic array fed
inverter. For obtaining required performance suitable control
circuit is designed by taking the output of the inverter and
comparing with reference value using PIC16F616
microcontroller. It controls and compares the input voltages
and provide an output pulse using PWM technique.
2. PROPOSED SCHEME
The block diagram of the proposed scheme is as shown in
Fig1. The output variation of PV array in solar power
technology depends on the temperature and intensity of
sunlight (radiation). The block diagram consists of main block
like PV array, inverter unit, filter circuit, step transformer,
PWM technique used for pulse generation to MOSFETs of the
inverter. Output voltage obtained from PV array is converted to
ac using 1-phase, 2-leg inverter. The ripples in the ac voltage
obtained from inverter are minimized using LC filter circuit.
The ripples free inverter output is stepped-up to 230v using
step up transformer.
Fig. 1: Block Diagram for proposed scheme
This supply is given to drive the load. The required
performance obtained by using PIC 16F616. It controls and
compares the input voltages and provide an output pulse using

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PWM technique, thereby required performance can be obtained
even though there is variation in temperature and radiation
parameter.
3. DEVELOPMENT OF CONTROLLER
The circuit diagram for proposed scheme shown in fig 2. A
variable DC supply is given as input source to the whole
circuit. This variable DC voltage is passed through a diode
which provides a unidirectional flow. From the diode it splits
into two. One branch is directly given to the centre tapped 12 -
0 – 12 V step-up transformer and the other branch is passed
through a voltage regulator for giving supply voltage to both
ICs.
The main components of this circuit are PIC 16F616,
ULN2003A, LM7805. In this PIC 16F616 provides the basic
operation. It controls and compares the input voltages and
provides an output pulse using PWM technique. This pulse is
of low values. So they are given to a driver circuit consisting of
ULN2003A having high current gain. The output of the driver
IC has sufficient value to drive the gate of MOSFET to which
they are connected.
According to the gate pulses given , their corresponding pair of
MOSFETs conducts and it will provides path for variable DC
voltage through centre tapped transformer . As a result of this,
an output voltage is induced at the secondary. This secondary
voltage is used for feedback. For the ease of control, this
feedback voltage is given to a step-down transformer and
further this AC is converted to DC using bridge rectifier. This
DC analog signal is passed through filters and resistors to
avoid the response for small variation of output voltage, thus
preventing flickering of load. After that , a zener voltage
regulator is provided to limit the input voltage to the PIC
within 5V.
Fig 2: circuit diagram
The input signal to PIC is given through pin 8. This pin
converts the DC analog signal to digital signal. A reference
signal to IC is given through a potential divider at pin 10 . So
PIC compares this input signal with reference value. According
to the error bits formed, the sine wave is modified using PWM
technique. As a result of this, pulse width of output varies
which will in turn varies the gate pulses to MOSFETs. In this
circuit, PIC is configured at half bridge PWM ie., there are two
outputs and one is complement of other provided with a small
dead delay .
4. FLOW CHART
5. RESULT AND DISCUSSION
The experimental model was constructed using a 30V variable
DC supply instead of PV array. The proposed scheme is tested
with R load (20 W lamp load). By varying the supply voltage
from 11 to 22 V, a nearly constant voltage of 200 V can be
measured using a voltmeter connected across the load. The
results thus obtained are tabulated as shown below:

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Table 1: Table of analysis
SOURCE
VOLTAGE (V)
OUTPUT
VOLTAGE (V)
11 199
12 200
13 201
15 199
18 200
20 198
22 200
Fig 3: Hardware model
6. CONCLUSIONS
The system described here is a PV system for low load
applications, using a single phase PWM inverter. The control
technique is easy to implement economically with analog and
digital components. The required performance can thus be
successfully obtained by using pic16F616.
The future work includes improving the stability of the system
and also to study various instability in PWM inverter with
harmonic analysis and ways to eliminate it. The circuit can be
further modified to provide protection against short circuits and
over current by adding additional features to the controller
PIC16F616.
ACKNOWLEDGEMENTS
This work was supported by Electrical and Electronics
Engineering Department, Mar Athanasius College of
Engineering, Kothamangalam.
REFERENCES
[1]. Arul Daniel’s, Santhoshkumar.B, and H. HabeebullaSait
“Analog controller for photovoltaic array fed inverter driven
Single phase induction motor” IEEE Conference 2009.
[2]. Dr. P.S Bimbra, Power Electronics,fiffth ed,New Delhi
publications,2012.
[3]. Raju. A. B, S. Ramesh Karnik and RohiniJyoti.“Maximum
Efficiency Operation of A Single Stage Inverter Fed Induction
Motor PV Water Pumping System”, First International
Conference on Emerging Trends in Engineering and
Technology
[4]. VarinVongmanee. “The photovoltaic pumping system
using a variable speed single phase induction motor drive
controlled by field oriented principle”, The 2004 IEEE Asia-
Pacific Conference on Circuits and Systems, December 6-
9,2004.
[5]. Ms SunithaUndrajavarapu, M Srinivasa Rao, Mr L Udav
Kiran “Photoyoltaic array fed Boost Spwm InverterDriven
Single-Phase Induction Motor”, The International JournalOf
Engineering Research and Applications (IJERA) ISSN: 2248-
9622 vol.2, issue 4, July August 2012, pp. 2136-2141

Photovoltaic array fed inverter

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