National Conference on Research Advances in Communication, Computation, Electrical
Science and Structures (NCRACCESS-2015)
IMPLEMENTATION OF SUPER LIFT LUO CONVERTER WITH MPPT
AND VOLTAGE BALANCING CONTROL FOR PHOTOVOLTAIC-FED
CONVERTER
1
2
Mrs. K.V. Dhamaraiselvi ; Mrs.P.Kalaiselvi
1,2 Department of EEE, Vels university school of engineering, Chennai, India
ABSTRACT
In the existing system photovoltaic
converter fed system , photovoltaic voltage
and current Need to be sensed to execute
maximum Power point tracking (MPPT)
control. For the proposed system using
super lift luo converter, to achieve MPPT
control , both the capacitor voltages need
to be sensed and an additional voltage
balancing control loop is required to
balance the capacitor voltages.
The positive output elementary super lift
Luo converter is a new series of DC-DC
converters possessing high-voltage transfer
gain, high power density, high efficiency ,
reduced ripple
Voltage and current. These converters are
widely used in computer peripheral
equipment , industrial applications and
switch mode power supply , especially for
high
voltage-voltage projects. In this
project, the voltage balancing
Control is obtained by Sensing only the
inductor current.
KEYWORD: Maximum power point
tracking, voltage balancing control loop,
Super lift luo converter.
I.INTRODUCTION
Solar Energy is the ultimate sources of energy,
which is naturally replenished in a short time
period of time, this is called “Renewable
Energy” or “Sustainable Energy”.
Thus the efficiency of solar cells mainly
depends on many factors such as temperature,
insolation, direct sunlight, and so on.
That ambient temperature can reduce the
photovoltaic (PV) array output power. In
addressing the poor efficiency of PV systems,
ISSN: 2348 - 8379
among many methods is proposed, among
which is a new concept called Maximum
power point tracking .MPPT works , let
assume your battery is low at 12 volts, A
MPPT takes that 17.6 volts at 7.4 Amps and
converts it down, so that what the battery gets
now 10.8 amps at 12 volts now you still have
almost 130 watts and everyone is happy.
The super lift luo converter have the
advantages of high-voltage transfer gain,high
power density, high efficiency, reduced ripple
voltage and current. These converters are most
widely used in computer peripheral equipment,
industrial applications and switch mode power
supply, especially for high voltage-voltage
projects. In this project, the voltage the voltage
balancing control is obtained by sensing only
inductor current.
The PV-fed converter, sensing both PV current
and voltage is required to achieve the
maximum power point tracking (MPPT)
control. Additionally, for super lift luo-type
converter, sensing additional capacitor
voltages is also required to detect the voltage
imbalance and force both capacitor voltages to
be balanced.
To overcome the voltage imbalance in the
output side we execute the method of using
voltage balancing control loop this is the
proposed technique in this project. This means
that sensing only PV current (ie., the inductor
current) is able to achieve both MPPT function
and the voltage balancing function. Finally
both the MPPT and voltage balancing control
can be achieved only by the use of proposed
sampling system (ie. by sampling the inductor
current values . And so the simulation and
experimental results are provided to verify the
proposed method.
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(fig.1 proposed circuit of super lift luo
II.SUPER LIFT LUO CONVERTER
converter with MPPT and voltage balancing
control loop)
Luo Converters
Luo converters are new series of DC/DC
converters developed by Fang Lin Luo. They
are made of a simple structure and cheap
topology. Luo claims
The
super-lift
breakthrough
technique
in
DC/DC
is
a
major
conversion.
.
Compared with the voltage-lift technique, its
voltage transfer gain is much larger. The
superior
super-lift technique implements an output
performance in terms of high voltage gain and
voltage increasing in geometric progression.
minimum output ripple. The converters are
This means that with the addition of the nth
developed based on two techniques, the
stage, the gain of the converter is equal to the
voltage-lift
super-lift elementary circuit raised to the nth
That
these
converters
technique
have
and
the
super-lift
technique. Luo converters are primarily used
to step-up (boost) DC voltage but some
circuits (such as the voltage Luo converters are
primarily used to step-up (boost) DC voltage
but some circuits (such as the voltage-lift
elementary) can also be used to step-down
voltage, similar to the buck-boost converter. In
existing
system
three
level
boost
type
converter is used to over come the number of
power.
The super lift luo converter have the
advantages of high-voltage transfer gain , high
power density, high efficiency, reduced ripple
voltage and current. These converters are most
widely used in computer peripheral equipment,
industrial applications and switch mode power
supply, especially for high voltage-voltage
projects.
switches we prefer super lift luo converter.
Because switching stress loss is mainly
A. Modes operation:
reduced.
Fig . 2 proposed circuit of super lift luo
converter when the switch is ON.
ISSN: 2348 - 8379
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National Conference on Research Advances in Communication, Computation, Electrical
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Mode:1 When the switch is ON the inductor
L1 is connected across the supply with C1 in
parallel is charged. Then C1 will get discharge
so the D1, D2 will not conduct.
B. Super-Lift Technique
Geometric Progression:
The main advantage of the super-lift
converters is their ability to reach very high
gains using geometric progression .The
voltage transfer gain duty ratio (1− V cont 1 )
and the average inductor current value is
follow
(id c )T s= (1− V c o n t 1 )( i L ) T s
Fig .3 2 proposed circuit of super lift luo
converter when the switch is OFF.
Mode:2 When the switch turns off, current
across the L1 start decreasing at same time
Since the average inductor current value is
(iL )T s = I L is therefore obtained by the
proposed sampling method P
can be
PV
rewritten as
voltage across the C1 increases and the diode
D1 and D2 starts conducting and C2 maintains
PPV = V d c (1− V c o n t 1 )I L
Hence the DC- bus voltage V
the output filter. It is done during the
V0
2− k
=
V in
1− k
( )
Gain for the Super-Lift elementary circuit with
n additional stages
Study of the above formulae shows the high
gains that are possible with multiple stage
super-lift converters, this is because n is a
power (instead as in voltage-lift where n is a
multiple). For this reason the super-lift
technique is very powerful and if implemented
correctly could be applied to many industry
applications.
III.PROPOSED MPPT AND VOLTAGE
BALANCING CONTROL LOOP
MPPT or Maximum power point tracking is
algorithm that included in charge controllers
used for extracting maximum available power
from PV module under certain conditions. The
voltage at which PV module can produce
maximum power is called „maximum power
point‟ (or peak power voltage).and this is the
major principle of MPPT. Maximum power
varies with solar radiation, ambient
ISSN: 2348 - 8379
dc
is well
regulated,
continuous conduction mode.
G=
( 2)
temperature and solar cell temperature etc.
Then MPPT checks output of PV module
compares it to battery voltage then fixes what
is the best power that PV module can produce
to charge the battery and converts it to the best
voltage to get maximum current into battery. It
can also supply power to a DC load, which is
connected directly to the battery. Now in this
project MPPT with sensing only inductor
current is done.
Let the PV power P is the product of the PV
pv
and the PV voltage V
if we are
PV..NOW
neglecting the power loss of the Super Lift
Luo converter, then the PV power can also be
expressed as the product of the dc-bus voltage
V
and the average bus current ( I )T
dc
dc S
within the switching period Ts
P p v = v p v × i pv= vdc × (id c )T s
( 1)
But in the Super lift Luo converter, the
average bus current (idc )T s is equal to the
product of the
The PV power P
is directly proportional to
PV
the product of the average inductor current I
L
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National Conference on Research Advances in Communication, Computation, Electrical
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c o nt 1 )
and the duty ratio (
Then the
proposed MPPT with sensing only inductor
current method is done by perturbation and
observation method.
After changes in the duty ratio as per the
signals V c ount the sampling of inductor
,
current and their new products are calculated
(ie new product
1− V
.
P' P V (n )= ( 1− V c o n t [n ]× I L [ n ])
Here from the above equation two
comparisons are done. The former comparison
is between the latest product P ' PV (n ) and the
previous product P' P V (n− 1 ) and then the
comparisons in done between the duty ratio
V c o n t (n )
and
the
previous
duty
V
[n−
1
]
ratio c o n t
.
IV .SIMULATION RESULT
Consider
one
of
P
'
(
n
)
>P'
(
n−
1
)
P
V
P
V
as
and
The main purpose of Simulation is that the
the
FIG.4
case
also
the duty ratio
should keep increasing to move to maximum
power point and the new control signal is
obtained by adding a constant ∆ V c ont 1 to the
control signal ∆ V c o n t 1 (n ). simultaneously the
V c o n t 1 (n )>V c o n t [n− 1 ]
duty ratio should also increase to move to the
maximum power point and also same as for
P' P V (n )< P ' P V (n− 1 )
the case of
and
V c o n t 1 (n )<V c o n t [n− 1 ] .
All the above equation is for MPPT for
sensing only inductor current and additionally
voltage balancing control loop is required to
detect voltage imbalance in the output side
and also to maintain constant output voltage.
discipline of designing a model of an actual or
theoretical physical system executing the
model on a digital computer, and analysing the
execution output. There are many methods of
modelling systems which do not involve
simulation but which involve the solution of a
closed-form system (such as a system of linear
equations). Simulation is often essential in the
following cases: 1) the model is very complex
with
many
variables
and
interacting
components, 2) the underlying variables
relationships are non-linear; 3) the model
Fig .4 Algorithm of Proposed MPPT with
sensing only inductor current.
contains random variants; 4) the model output
is to be visual as in a 3D computer animation.
The software used for simulation is MATLAB
.There are many components like PV module,
proposed MPPT with sensing only inductor
current, voltage balancing control loop and
Super Lift Luo converter.
ISSN: 2348 - 8379
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National Conference on Research Advances in Communication, Computation, Electrical
Science and Structures (NCRACCESS-2015)
After using the proposed MPPT with sensing
only inductor current and also the voltage
Fig .5 Simulation model of proposed circuit
balancing control ,the output voltage can be
seen, since by giving 12 volts of input and the
output can be increased by three times than the
input ,now the output voltage is 60 volts. In
this proposed project the switching loss is
reduced compare with the existing system and
main advantages are high voltage transfer
gain,
reduced
ripple
voltage
and
high
efficiency.
The simulation of output voltage is shown in
fig 7
Fig.5
Fig .6 Simulation of proposed circuit of super
lift luo converter with MPPT sensing only
inductor current and voltage balancing control.
Fig.7voltage v Time
s
The simulation of output current with sensing
only inductor current is shown in fig .8
Fig. 6
ISSN: 2348 - 8379
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National Conference on Research Advances in Communication, Computation, Electrical
Science and Structures (NCRACCESS-2015)
Electron., Vol 58, No.4 , Pp. 1239-1250,April
2011.
2.
E.Ribeiro, A. J. M. Cardoso, Andc.Boccaletti,
“Fault-Tolerant Strategy For A Photovoltaic DcDc Converter”, Ieee Trans.Power Electron, Vol
28. No.6 Pp.3008-3018,,Jun 2013
3.
K.Ramash Kumar, S. Jeevananthan, “Pi Control
For Positive Output Elementary Of Super Lift
Luo Converter.World Academy Of Science
Engineering And Tecnology Vol.4 2010-03-23
Fig .8 current v Time
s
4.
Finally the output voltage and output current
can seen by the simulation diagrams.
E.Koutroulis,K.Kalait
Zakis, And N. C.
Voulgaris, “Develop Ment Of A Microcontroller
-Based, Photovoltaic Maximum Power Point
Tracking Control System,” Ieee Trans.Power
Electron Vol.16, No.1
Pp.46- 54.
V. CONCLUSION
5.
This paper represents the performance of
J. M.Kwon\, B. H. Kwon, And K.
H.
Nam, “Three Phase Photovoltaic System
With
proposed MPPT with sensing only inductor
Three- Level Boosting Mppt Control”, Ieee
current and voltage balancing control loop
Trans. Power Electron., Vol 23,
with the Super lift luo converter which mainly
2327,Sep. 2008.
Pp.2319-
reduces the sensor count and reduces the
switching losses, high voltage transfer gain is
obtained and voltage imbalance is detected by
using voltage balancing control in output side.
The converter can execute maximum power
from the PV panel for a given temperature and
insolation by increasing the duty ratio the
output voltage can also be increased. In future
development it can be extended by converting
DC-DC output to AC by connecting an
inverter which can used for high voltage
industrial purpose.
REFERENCES
1.
W. Li And X He, “Reveiw Of Nonisolated High
Step-Up Dc-Dc Converters In Photovoltaic Grid
–Connected
Applications,”Ieee
ISSN: 2348 - 8379
Trans.
Ind.
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