1. An Efficient Sola
Aswathi Unni
M.Tech Scholar
College of Engineering
Trivandrum
Email: aswathiunni9@gmail.
Abstract— This paper proposes an effi
induction motor drive system using a pus
and a three-phase inverter with the solar
of energy for water-pumping applicatio
being increasingly employed for this purp
DC-to-DC boost converter has been emplo
up the solar array DC voltage. In this pap
more efficient topology for the proposed d
methods of PWM techniques , namely
width modulation (SPWM) and space ve
modulation (SVPWM), for inverter
implemented on the system and a
Furthermore , Volts/Hertz (V/f) control t
to maintain constant flux within the i
Incremental conductance algorithm is
maximum power point tracking (MPPT)
at every instant. Finally , simulation of thi
in MATLAB/SIMULINK in order
effectiveness of the proposed design.
Keywords—Photovoltaic;Power Electronics;
Converter; SVPWM; SPWM; Maximum
Tracking;;Three-Phase Inverter; Induction Mot
I. INTRODUCTION
The energy crisis that is being experienc
has led to the need for more efficient
Photovoltaic power is a source of energy th
energy in an efficient way at low cost [1].T
of availability of drinkable water in rural are
availability of electrical supply. This leads t
energy for water pumping systems and do
Solar energy, which is available in abundan
for this purpose. A solar water pump utili
motor pump in most cases due its high deg
low cost, higher efficiency and low maintena
In the proposed system, sinusoidal pulse
(SPWM) and space vector pulse width modu
for inverter switching are implemented and
as to determine the more efficient method
harmonics [4] .It is required to have a p
interface in order to transfer the PV energy
motor. The following sections elaborate this
ar Powered Induction
System
com
M
Asst
Government E
Email: m
icient topology of
sh-pull converter
r array as source
on. PV energy is
pose. A push-pull
oyed for stepping
per , to obtain the
drive system , two
sinusoidal pulse
ector pulse width
switching are
re compared.
technique is used
induction motor.
used to achieve
of the PV array
is system is done
to verify the
; DC-DC Push-Pull
m Power Point
tor
ced today globally,
t energy sources.
hat generates clean
There is a shortage
eas due to the non-
to use of alternate
omestic purposes.
nce can be utilized
izes the induction
gree of robustness,
ance cost [2].
width modulation
ulation (SVPWM)
are compared so
d for reduction of
power electronics
y to the induction
interface .
II. METHODOLOGY
The basic operation sch
represented in a block diagram
Fig. 1 Block Diagra
As shown in this diagram th
operating the induction mach
array generates a DC voltage
push-pull DC-DC boost conver
The pulses required to switc
obtained using the MPPT wh
conductance algorithm. This
power transfer at all instants. I
the DC voltage produced at th
converted to AC voltage by a
phase inverter is switched us
pulse width modulation , nam
modulation (SPWM) and space
(SVPWM) and the more effi
This voltage that is generated
the three-phase induction mac
operate it. The flux within the
using Volts/Hertz control. Th
each stage in the proposed syst
A.Photovoltaic Panel
PV array consists of a num
series and/or parallel. A bas
junction semiconductor and it
Motor Drive
Mini.V.P
t.Professor
Engineering College
Idukki
minivp@cet.ac.in
eme of the proposed system is
, as shown in Fig.1
am of Proposed System
he energy source that is used for
hine is solar energy. The solar
which is boosted up using the
rter as depicted in the diagram .
ch the push-pull converter is
hich employes the incremental
helps to maintain maximum
In the next stage of the system ,
he push-pull converter output is
three-phase inverter.This three-
sing two different methods of
mely , sinusoidal pulse width
e vector pulse width modulation
ficient method is implemented.
, is applied across the stator of
chine, after filtering, in order to
machine is maintained constant
he following sections elaborate
tem.
mber of PV panels connected in
sic PV cell consists of a p-n
converts sunlight into electrical

2. energy. A PV cell has non-linear I-V chara
be described by its equivalent circuit shown i
Fig. 2 Equivalent Circuit of PV Cell
The power output of a PV array depend
irradiance, panel temperature, and relation
operating voltage and current.
The following exponential model is use
predict the behavior of the photovoltaic modu
to this model, maximum power, equals
1
b =
Where is the short circuit current
circuit voltage, is the optimal curren
optimal voltage. b is obtained from equati
of b is unique for each and every solar pan
fluctuate with changes in irradiance and solar
B.Maximum Power Point Tracking
Maximum Power Point Tracking (
important in solar power applications beca
maximum power at each and every instant
the efficiency of the system and helps redu
solar array. Incremental Conductance(IC) m
this paper for MPPT which is , comparative
accurate, and rapid and is a low cost techni
the need for complicated mathema
[3].Incremental Conductance method uses t
source voltage and current to find the desire
From the P-V curve of a PV module it is sh
zero at maximum point, so the formulas
implies that the slope of the PV array powe
the MPP, increasing on the left of the MPP
the right hand side of the MPP.
= 0 at MPP
acteristics and can
in Fig. 2.
l
ds upon the solar
nship between the
ed to describe and
ule [2]. According
:
(1)
(2)
(3)
t, is the open
nt and is the
on (2). This value
nel and it does not
r cell temperature.
(MPPT) is very
ause it helps track
t , thus improving
uce the cost of the
method is used in
ely more efficient,
ique which avoids
atical operations
the information of
ed operating point.
hown that slope is
are as follows. It
er curve is zero at
and decreasing on
(4)
> 0 left of M
< 0 right of M
Fig. 3 Incremental Condu
In this flow chart, V(k) is t
I(k) is the newly detected curr
the previous detection values. W
the slope of the power curv
implies that the system is op
mode dc-dc converter in the
adjust the voltage and current
transfer maximum power at eve
C. DC-DC Push-Pull Converte
Maximum power point trac
is done using a switched mod
Here, for achieving that goa
converter is being used. Push-P
suitable choice to boost the vo
gives an efficiency of eighty-f
transformer is the preferred c
transformer applications exc
provides the advantage of i
voltage is the PV array voltag
(E) depends on the input volta
the high frequency transformer
MPP (5)
MPP (6)
uctance Algorithm Flow Chart
the newly detected voltage and
rent, and V(k-1) and I(k-1) are
When equation (4) gets satisfied
ve will become zero, and that
perating at MPP. The switched
stage after the solar panel will
t values in such a way so as to
ery instant.
er
cking of the photo voltaic panel,
de DC-DC power converter[4].
al, a push-pull DC-DC power
Pull type DC - DC converter is a
oltage from low to high value. It
five percentage. This push pull
hoice in high power switching
ceeding one kilowatt and it
isolation. The push-pull input
e. The push-pull output voltage
age (V), the duty cycle (D), and
r turns ratio (n),

3. Fig.4 Schematic diagram of Push-Pull Converter
In the proposed system design a DC-DC push-pull
converter, that successfully steps-up PV arrays 50V DC output
voltage into 680V DC has been implemented.
D. Sinusoidal Pulse Width Modulation of DC-DC Three-
Phase Inverter
In SPWM switching control, in a three-phase two-level
inverter; three sinusoidal signals (called as reference signals)
of 50Hz are generated and are delayed by 120 degree with
respect to each other .This is compared with high frequency
triangular wave in order to get the resulting switching gate
pulses for the inverter MOSFET switch .
The main factors that influence the performance of the
SPWM inverter are modulation index Ma and frequency
modulation Mf. It is simple and linear, but results in poor
voltage utilization. Frequency of the output wave depends
upon the switching frequency.
Fig. 5 Two-Level Inverter
E. Space Vector Pulse Width Modulation of DC-DC Three-
Phase Inverter
SVPWM is a popular and very efficient method used to do
the switching in inverters. By the use of SVPWM technique,
the fundamental component of the output voltage can increase
up to 27.39% compared to that produced by the SPWM
technique due to better DC bus utilisation. Hence, the size of
filter used can be reduced considerably [6] .
The main idea of SVPWM is to generate the appropriate
PWM signals so that vector with any desired angle can be
generated. In the space vector modulation, a three-phase two-
level inverter can be driven to eight switching states where the
inverter has six switching states (1-6) and two zero states (0
and 7) .
Fig. 6 Space Vector diagram for two-level inverter
The space vector diagram of the two level inverter is
presented in Fig. 6. Among the eight switching states, two are
zero states and the others are active states.The reference space
vector (Vref) for the space vector modulation can be
synthesized by three stationary vectors.
(7)
(8)
Where , , are dwell times for the vectors , ,
,respectively.
Thus, the output of the SVPWM based three-phase two-
level inverter yields a three-phase alternating output.
However, the output of an inverter, is a square waveform due
to the on/off states of the switches. Later it is converted to sine
waveform by employing the low pass LC filter.
F.Induction Motor
Induction motors are widely used in varied applications
due to its rugged construction, greater reliability and lower
cost . These motors require less maintenance because they
don’t have brushes and slip rings. Induction motors are
widely chosen for variable speed applications in industrial as
well as in domestic applications where AC line power is
available [5]-[6]. In the proposed system the induction motor
is used for water pumping system as shown in Fig. 1.The
induction motor synchronous speed is defined by following
equation,
(9)
Where f is the frequency of AC supply, n, is the speed of
rotor; P is the number of poles per phase of the motor. By
varying the frequency of control circuit through AC supply,
the rotor speed will change. In the proposed system, a 4kW ,
400Volt, 1430rpm , 4 pole , 50Hzthree-phase induction motor
is employed.
G. Control Strategy of Induction Motor
V / f control speed control technique (frequency control) is
used in the proposed system for maintaining V/f constant in
the induction motor [5] .

4. Any change in voltage to the input of the motor , without
change in its frequency will cause a change in flux of the
motor. Increase in flux will cause saturation of rotor and stator
cores , which will further cause increase in no load current of
the motor [7]. That means it is important to maintain flux (Φ)
constant and it is only possible by changing frequency too as it
is the only other variable term. If the voltage is reduced then
frequency must be reduced to make the flux constant. Hence
we are keeping the ratio of V / f constant.
III.RESULTS AND DISCUSSION
The proposed design is verified by computer simulation
using MATLAB/ SIMULINK software. Our proposed system
design consists of a solar panel followed by a series of power
electronics interface that runs an induction motor.
The main aim of any modulation technique is to obtain
variable output having maximum fundamental component
with minimum harmonics. The objective of pulse width
modulation techniques is enhancement of fundamental output
voltage and reduction of harmonic content in three phase
voltage source inverters. In this paper SPWM and SVPWM
techniques have been implemented on the induction motor
drive system and compared. Simulink models have been
developed for Sinusoidal PWM (SPWM) and Space vector
PWM (SVPWM) switching pattern.
A PV array basically consists of a number of PV panels
made of basic solar cells as shown in Fig. 2. Here, PV array
has been designed for a maximum power output of 6kW.
The panel is simulated at STC conditions of 25-degree
Celsius and the irradiance is varied between 1000W/ and
800 W/ . A voltage of 75 Volt DC was generated by the PV
array.
Next, the push-pull converter was coupled with the solar
array which successfully steps up the solar array voltage from
75V DC to 600V DC using an appropriate number of
transformer turns ratio. To transfer maximum power to the
load at all instants incremental conductance algorithm is used
for MPPT. The push pull converter is switched at a frequency
of 1 KHz with a duty cycle of 50 percentage. This DC output
of the push-pull converter is applied to the three-phase inverter
and the following outputs are obtained.
The following are the outputs of the drive system when
SPWM switching is done for the inverter.
Fig. 7 Inverter Output Voltage
A voltage of approximately 440Volt is obtained when
SPWM switching is applied.
Fig.8 Stator Current
The stator current settles at a steady state value of 6A after
t = 0.2 sec.
Fig. 9 Speed of the motor
A load of 10Nm was given to the motor at t=0.7sec. It can
be observed from the graph that when SPWM is used for
switching the three-phase VSI , the motor settles at the rated
speed of 1430rpm at t=0.2sec.
Fig. 10 Motor Torque
The motor settles at a torque of 10Nm when the load is
applied at t = 0.7sec.The motor torque has ripples initially ,but
settles down eventually. As can be observed in the speed and
torque graphs , the irradiation was reduced from 1000W/m2
to
800W/m2
at t=1sec in order to analyze the performance of the
motor. At this instant as the voltage reduces , corresponding
change in frequency is brought about by the V/f control used
in this system in order to maintain flux constant. The MPPT
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
-500
0
500
Time (seconds)
Voltage(V)
Time Series Plot:
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
-30
-20
-10
0
10
20
30
Time (seconds)
Current(A)
Time Series Plot:
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
0
200
400
600
800
1000
1200
1400
1600
Time (seconds)
Speed(rpm)
Time Series Plot:
0 0.5 1 1.5 2
-20
-10
0
10
20
30
Time (seconds)
<ElectromagnetictorqueTe(N*m)>
Time Series Plot:<Electromagnetic torque Te (N*m)>

5. changes the pulse width to the converter as a
across a change in voltage at its input .Hen
slightly varied , initially , in order to track t
maximum power is transferred , correspond
radiation.
The THD of the inverter output voltage
are as shown below.
Fig. 11 Inverter Output Voltage
Fig. 12 Stator Current THD
The THD is obtained using FFT A
MATLAB/SIMULINK. It is observed th
switching is done on the inverter, its output v
of 4.14% , and the stator current of the mo
1.28%.
The following are the outputs when SV
inverter switching
Fig. 13 Inverter Output Voltage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0
-600
-400
-200
0
200
400
600
Time (seconds)
Voltage(V)
Time Series Plot:
and when it comes
nce , the speed is
the point at which
ding to a particular
and stator current
THD
Analysis Tool in
hat when SPWM
voltage has a THD
otor has a THD of
VPWM is used for
(V)
As shown in the graph,
implemented on the same indu
output of the inverter is observe
Fig. 14 Stat
Fig.15 Speed
It is observed that when SV
speed of the motor settles at
0.16sec. In this case also , th
analyzed by changing the r
800W/m2
.
Fig. 16 Mot
The following graphs depic
voltage and the stator current
switching is done for the invert
0.8 0.9 1
0 0.1 0.2 0.3
-30
-20
-10
0
10
20
30
Ti
Current(A)
0 0.2 0.4 0.6 0.8
0
200
400
600
800
1000
1200
1400
1600
Time
Speed(rpm)
Tim
0 0.5
-30
-20
-10
0
10
20
30
40
<ElectromagnetictorqueTe(N*m)>
Time S
when SVPWM switching is
uction motor drive system , the
ed to be 500Volt .
tor Current
d of the motor
VPWM switching is done , the
t rated speed 1430rpm at t =
he performance of the motor is
radiation from 1000W/m2
to
tor Torque
ct the THD in the inverter output
, respectively ,when SVPWM
ter .
0.4 0.5 0.6 0.7 0.8
ime (seconds)
Time Series Plot:
1 1.2 1.4 1.6 1.8 2
(seconds)
me Series Plot:
1 1.5 2
Time (seconds)
Series Plot:<Electromagnetic torque Te (N*m)>

6. Fig.17 Inverter Output Voltage TH
Fig. 18 Stator Current THD
It is clearly observable from the gra
been reduced when SVPWM switching is do
SPWM switching. The inverter output voltag
be 1.49% and stator current THD is 0.95%.
TABLE I
COMPARISON BETWEEN PERFORM
SPWM AND SVPWM
Modulation
Method
Voltag
e THD
(after
filterin
g)
RMS
Output
Voltage(V
)
Cu
TH
(af
fil
)
SPWM 4.14% 440 1.2
SVPWM 1.43% 500 0.9
IV. CONCLSION
In this paper an effective method to dr
squirrel cage induction motor for water pum
fed from a solar PV array is presented. Ba
result it is demonstrated that the inductio
effectively driven by PV energy. Maximum p
effectively from panel using MPPT (IC) tec
pull converter. The SPWM and SVPWM
inverter switching were implemented on
SVPWM technique was found to give lesser
better performance. By keeping voltage to
constant the flux of the motor is maintained
the three-phase inverte. The physical fabric
HD
aph that THD has
one, compared to
ge is observed to
MANCE OF
urrent
HD
fter
ltering
Stator
Curren
t (A)
28% 5
95% 6
rive a three-phase
mping application,
ased on simulation
on motor can be
power is extracted
chnique with push
M techniques for
the system and
r THD and hence ,
o frequency ratio
d constant through
cation and test of
the proposed design is yet to be
in future.
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