Simulation of a Solar System by Using SPWM
Inverter
Satish
Undergraduate Student
Dept. Of Electrical and Electronics Engg.
PES University Bangalore Karnataka.
Abstract :- Solar system is a system that generates
electric power from solar energy. Solar energy is the
one of the most promising Renewable energy sources
(RES). A power electronic converter which converts
DC power from PV array to AC power at required
voltage and frequency levels is known as a
inverter.generally different pulse width modulation
(PWM) techniques
It comprises have been
implemented for grid connected 3-phase voltage source
Inverter (VSI) System.in .However, a high voltage gain
converter is essential for the PV module because of
irregularities in solar energy, In this paper the SPWM
inverter is used to reduce the harmonics and to get a
proper sin wave at the end of the proposed system.
The gating signal for the three phase SPWM inverter
switch is generating by comparing the triangular wave
and sine wave which drives the inverter switches. The
LC filter is used to to get the pure sine wave.
Key words - Solar PV, Boost Circuit, DC microgrid,
SPWM Inverter
switching algorithms. simulation a PV system and analysis
one of the important factor for analyzing the behaviour
The modeling of the inverter system is done technique by
such as SPWM technique The DC-DC to converter and
inverter are extensively explored to meet the requirements
for the RES . SPV system produces dc voltage and voltage
source inverter(VSI) is utilized in this system as a DC-AC
converter which converts dc voltage into AC voltage. As
the PV system operating in distributed generation the
power supplied to the consumer load needs to be regulated
on standard range. In this paper SPWM technique have
been discussed for three phase VSI used in grid connected
SPV system and mathematical model of an inverter with
with LC filter circuit has organized.
II. BLOCK DIAGRAM OF A PV SYSTEM
The block diagram of a solar PV system with a SPWM
inverter is shown in Fig. 1.1, where we can see the output
of the solar panel is given input to the boost circuit, where
the stepping up of voltage is done, and after that, the threephase SPWM inverter is connected.
I. INTRODUCTION
In the today's world the demand for renewable energy
sources and achieving energy efficiency becomes are more
significant. From smart cities to the rural areas,
inexhaustible solar power has been viewed as one of the
promises renewable energy sources that offers hope for the
future of energy. The PV systems are gaining popularity
more than the RES because of their ease of installation,
less maintenance, increasing efficiency of solar cell and
economics of scale and energy policy. Power from PV
system is directly feeding into electric microgrid. The
output power of the solar varies with weather condition
and irradiation levels. So power Electronic converters are
required to be increase the efficiency of the system which
supplies the good power with good quality to the
consumer load. The application for efficient utilization of
these sources.
Grid connected inverter technology is one of the key
technology for grid connected Solar PV system in order to
achieve reliable and safety operation. An inverter is a
power electronic converter which consist of switching
devices and inverter operation also depend on the
fig1.1 Block diagram of PV system
The three phase inverter is used to convert DC voltage to
the three phase AC voltage and feeds the energy to the
load through the LC filter circuit. The inverter has to be
controlled in order to obtain harmonic less voltage to
achieve good power quality. Various PWM technique are
used to switch the inverter circuit. SPWM is used in this
proposed paper
Table.1
Eq.3 Formula for calculating the Capacitor value
Solar Module Specification
C
Maximum Power (Pm)
213.5 W
Number of Cell per module
60
Short Circuit Current (Isc)
7.84 A
Open Circuit Voltage (Voc)
Voltage at max power point (Vmp)
36.3 V
29 V
Current at max power point (Imp)
7.36 A
Irradiance (W/m^2)
Temperature (Deg.c)
1000 W/m^2
25 deg.c
The table.1 provides parameters for a PV array. These
parameters are for a PV array in MATLAB SIMULINK.
The maximum power is the output of the power of the PV
module under optimum condition. In this case it is
specified as 213.5w. The PV array consist of a number of
modules and each module and each module contains 60
cells. A short circuit current is produced by the PV module
that is 7.86A open circuit voltage 36.3V is voltage across
the module when there is no load connected . Voltage at
maximum power point 29V and current at maximum
power point 7.36A is the voltage and current at which the
solar module operates at its maximum power output.The
number of panel are connected in series is 5 volt to get the
1kw power output.
Io D
f s Vc
Eq.4 Load at Rated Power
𝑅=
𝑅2
𝑅
The following parameters are taken into consideration
while calculating the Inductor and Capacitor of Boost
Circuit. In the above equations, 𝑅𝑅 is Input Voltage,
𝑅𝑅 is Output Voltage, 𝑅𝑅 is Line Current, 𝑅𝑅 is
Switching Frequency, P Output Rated Power, Ripple
Voltage = 1%,
Ripple Current = 20-30%, D is Duty Cycle. The Boost
Circuit output is connected to DC Load. For AC load the
Inverter Circuit is connected in series. To feed the power
to the AC load the Inverter is connected between the
output of the boost and AC load.
III. BOOST CIRCUIT CALCULATION
Fig.1.2 Boost Circuit
The above figure represents the boost circuit which is
using to boost the output voltage of a PV panel. In real life
the output of a solar panel will not be the constant there
will be a fluctuation in the output of the PV panel which
can be make stable by suing the boost circuit. The design
of a boost circuit is done with the following formulas
Eq.1 Duty Cycle D  1 
Vin
Vout
Eq.2 Formula for calculating the Inductor value
L
VS (min) D
f s Vc
Fig.1.3 Input and output voltage of the Boost circuit
IV. MODELING OF A SPWM INVERTER
In a SPWM (Sinusoidal Pulse width modulation) inverter,
were basically comparing two kinds of waves a smooth
sine wave and a triangular wave that is shown in the fig1.3
We use these waves to generate the output voltage of the
inverter. The sine wave represents the desired voltage we
want to achieve.
upper switch is getting turned ON and lower switch is
turned OFF. Based on switching state positive or
negative half DC link voltage is applied to each phase.
Usually the switches are controlled in pairs (S1,S4),(S3,S6)
and (S5,S2) and the logic is shown in Table
II.measurement is used to output the three phase voltage
and Current wave form
Eq.2 Inverter formula
Vac 
Fig.1.3 SPWM Generation
We compare it with the triangular wave. The point where
they meet determine when the inverter switches on and off,
which controls the width of the pulses.
Imagine the sine wave and the triangular wave are like two
lines on a graph. When the sine wave is higher than the
triangular wave, it tells the inverter to produce a high
voltage output. When it's lower, the output voltage is low.
This comparison happens in a device called a comparator.
Depending on whether the sine wave is higher or lower
than the triangular wave, the comparator sends out either a
"high" or "low" signal. This signal then goes to another
part of the system, which adjusts the width of the pulses
that the inverter produces. This ensures that the output
voltage follows the shape of the sine wave closely. In this
3
Vdc
2 2
To get the output voltage 400AC input voltage be around
653V dc input to the inverter circuit
Fig. 1.5 Carrier wave and modulation wave
setup, the inverter is connected to other components like a
boost converter and operates at specific frequencies and
phase shifts to generate a three-phase AC voltage
waveform. So, in simpler terms, a SPWM inverter
compares smooth and triangular waves to control the
width of pulses, producing a voltage that mimics the
desired sine wave output
V. SIMULATION AND RESULTS
The simulation of a PV system with SPWM inverter is as
shown in the fig.1.5
Fig. 1.6 Simulation of a PV system with SPWM Inverter
Fig.1.4 Simulation of SPWM Inverter
The above fugure shows the Three phase V-I .the 3-phse
VSI having six switches with each phase output is
connected to middle of the comparator forms the control
signal for each leg of the inverter . in one lag, two
switches makes a phase and these two switches open and
close in a complementary fashion. The total voltage is Vdc
therefore the each pole voltage of the inverter varies. If the
which boost converters are connected, Perturb and
Observe using an MPPT on the PV cell, which produces
the electrical power at a 25°C temperature and an
irradiance of this PV module is kept in between 500 800W/m2. From the PV array take the data of Trina solar
250 PA from this data sheet connected 5 modules are
connected in series and 1 modules are connected in
parallel. So each panel will give around 29v each panel
consists of 60 cells. One panel gives an open circuit
voltage near about 37.6 volts. This solar panel is
connected to the boost converter. In a solar panel, each
module produces a different output voltage. A solar panel
consists of a non-uniform power supply. For providing
constant dc voltageThe modeling and simulation has been
done for SPWM technique using Matlab/Simulink. The
system parameters for 3-phase VSI are given in Table IV.
Various simulation results are analyzed and presented on
the inverter and load side of the proposed system in order
to demonstrate the satisfactory performance of sine-PWM
technique for grid connected solar PV system. Inverter
output phase voltage, line voltages and load line voltages
and phased currents are obtained through simulation. The
LC filter is simulated through state space model in the
Matlab/Simulink.
side of the proposed system in order to demonstrate the
satisfactory performance of sine-PWM technique for grid
connected solar PV system
REFERENCE
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Fig.1.7 Output of SPWM Inverter
Inverter output line to line voltages are given in Fig. 9.
The vos iiA, iiB, iiC. Load line to line voltages and load
phase currents iLA, iLB, iLC are given in Fig. 1.7. Inverter
output line to line voltages (ViAB), Inverter output currents
(iiABC), load line to line voltages (VLABC) andltages are
called as ViAB, ViBC, ViCA.
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Fig.1.8 Output of SPWM inverter with pure sinwave
VI. CONCLUSION
Increasing demand on energy efficiency and power quality
issues, grid connected solar PV systems is taking a good
place.In this paper SPWM and SVPWM techniques have
been discussed for 3-phase grid connected VSI. The LC
filter circuit is used in the proposed system. This filter
circuit is mathematically modeled by using state space
analysis and complete state space equation is obtained.
The SPWM technique is implemented and simulated on 3
phases VSI using state space model of the LC filter circuit
for grid connected solar PV system. Various simulation
results are analyzed and presented on the inverter and load
[6]Won-Kyun Choi,Feel-soon Kang“H-bridge based
Multilevel Inverter using
PWM Switching Function”2009 Telecommunications
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