International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.com March 2015, Volume 3 Special Issue, ISSN 2349-4476
Implementation of Solar Power Converter for DC Distribution
by Incremental Conductance Controller
SHILPA C
2 year, M. Tech, EEE Dept.
Kuppam engineering college
Kuppam, Andhra Pradesh
nd
S. ZABIULLAH
Assistant Professor
Kuppam engineering college
Kuppam, Andhra Pradesh
Dr. VENUGOPAL. N
HOD of EEE & Director, R&D
Kuppam engineering college
Kuppam, Andhra Pradesh
ABSTRACT
Solar energy is clean and is abundantly available. Solar technologies use the sun to provide heat,
light, electricity, etc for domestic and industrial applications. With the alarming rate of depletion of
the major fossil fuels and climate changes, a problem grows severe day by day. It has become an
urgent necessity to invest in renewable energy resources that would power the future sufficiently
without degrading the environment through greenhouse gas emission. The energy potential of the sun
is immense, but despite this unlimited solar energy resource, harvesting it is a challenge mainly
because of the limited efficiency of the array cells. Solar power converter consists of coupled
inductor and switched capacitor technologies to obtain maximum voltage gain, the leakage inductor
energy from the coupled inductor can be recycled. The voltage stress on active switch is reduced,
which means the coupled inductor employed in combination with the voltage multiplier technique
successfully accomplishes the higher voltage gain. There are various MPPT techniques among the
various techniques we are chosen IC (Incremental Conductance). This will helps to improve the
system efficiency by a low voltage rating and low conductance resistance. The duty ratio is
modulated by the MPPT algorithm, designing and modeling of the proposed work is carried out and
results are verified with the help of MATLAB/Simulink.
Keywords
Solar power converter, photo-voltaic (PV) array, maximum power point tracking (MPPT), sinusoidal
pulse generator (SPWM).
I.
INTRODUCTION
Renewable energy is the energy which comes from natural resources such as sunlight, wind, rain,
tides and geothermal heat. These resources are renewable and can be naturally replenished.
Therefore, for all practical purposes, these resources can be considered to be inexhaustible, unlike
deteriorating conventional fossil fuels. The global energy crunch has provided a renewed impetus to
the growth and development of Clean and Renewable Energy sources. In this presentation we
considered the solar energy as renewable energy resource. Solar energy is abundantly available that
has made it possible to harvest it and utilize it properly. Solar to electrical energy conversion can be
done in two ways, namely solar thermal and solar photovoltaic. Solar thermal is similar to
conventional AC electricity generation by steam turbine excepting that instead of fossil fuel.
The use of a micro inverter or ac module has recently been proposed for individual PV panels.
Although this discrete PV power generation solution may partially eliminate the shadow problem, a
micro inverter structure constrains the system energy’s harvesting efficiency and entails high costs.
A solar power optimizer (SPO) was developed as an alternative to maximize energy harvest from
each individual PV module. An SPO is used as a dc–dc converter with maximum power point
tracking (MPPT), which increases PV panel voltage to optimum voltage levels for a dc micro grid
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SHILPA C, S. ZABIULLAH, Dr. VENUGOPAL. N
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.com March 2015, Volume 3 Special Issue, ISSN 2349-4476
connection or through a dc–ac inverter for electricity. “Figure 1” shows a single PV panel’s energy,
which passes through a Solar Power Optimizer to a dc micro grid system.
Fig: 1. Configuration of multi-parallel SPO for a dc-micro grid system.
A 400 V dc-micro grid system was proposed as an energy-efficient distribution option for data center
systems and telecommunication facilities. The SPO attempts to improve the use of distributed
renewable resources and lower system cost. It may also potentially improve the efficiency of PV
systems, has shadow effect, and can monitor the status of PV modules. Moreover, the dc-grid voltage
is regulated by bidirectional inverter and battery tank. In case of low-loading condition, the
redundant energy will store into battery or through bidirectional inverter to ac grid. The maximum
power point (MPP) voltage range of a single PV panel ranges from 15 to 40 V and has a power
capacity of about 100W to 300W.
A high step-up solar power converter increases low-input voltage to a sufficient voltage level.
Various step-up dc–dc converter topologies include a conventional boost and fly back converters,
switched inductor converter, and switched capacitor converter. Boost types that are integrated with
coupled inductors. With increasing voltage gain, recycling the leakage inductance energy of a
coupled inductor will reduce the voltage stress on the active switch, which enables the coupled
inductor and voltage multiplier or voltage-lift technique to realize high-voltage gain.
II.
PROPOSED SYSTEM MODEL
The “Figure 2” consists of solar boost converter includes a floating active switch S 1 and a coupled
inductor T1 with primary winding N1, which is similar to the input inductor of a conventional boost
converter capacitor C1, and diode D1 recycle leakage inductance energy from N1.
Fig.2. Configuration of the proposed system.
Secondary winding N2 is connected to another pair of capacitors C2, and C3, and to diodes D2 and D3.
Rectifier diode D4 connects to output capacitor C0 and load R. The duty ratio is modulated by the
MPPT algorithm, which uses the incremental conductance method that is employed in the proposed
system. It detects PV module voltage Vpv and current Ipv to determine the increase and decrease in
the duty cycle of the dc converter.
The efficiency of a solar cell is very low. In order to increase the efficiency, methods are to be
undertaken to match the source and load properly. One such method is the Maximum Power Point
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SHILPA C, S. ZABIULLAH, Dr. VENUGOPAL. N
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.com March 2015, Volume 3 Special Issue, ISSN 2349-4476
Tracking (MPPT). This is a technique used to obtain the maximum possible power from a varying
source. In photovoltaic systems the I-V curve is non-linear, thereby making it difficult to be used to
power a certain load. This is done by utilizing a boost converter whose duty cycle is varied by using
a MPPT algorithm.
III.
MAXIMUM POWER POINT TRACKING
The efficiency of solar cell is very low. In order to increase the efficiency, methods are to be
undertaken to match the source and load properly. One such method is the Maximum Power Point
Tracking (MPPT). This is the technique used to obtain the maximum possible power from a varying
source. In photo-voltaic systems the I-V curves are non-linear, thereby making it difficult to be used
to power a certain load. This is done by utilizing a boost converter whose duty cycle is varied by
using MPPT algorithm. A boost converter is used on load side and a solar panel is used to power this
converter.
Methods for MPPT
There are many methods used for maximum power point tracking a few are listed below:

Perturb and Observe method

Incremental Conductance method

Parasitic Capacitance method

Constant Voltage method

Constant Current
In this paper we are chosen the incremental conductance method as MPPT controller.
Comparisons of incremental conductance over perturb and observe algorithms

In Incremental Conductance Algorithm can determine in which direction it has to do voltage
changing. Therefore, IC method does not track in the wrong direction even under rapidly changing
condition where as in P and O method fails to track under fast varying atmospheric condition due to
this there some power loss occurs.

IC method can determine the maximum power point without oscillating around this value. In
case of P and O method cannot determine when it has reached the maximum power point.

In IC method the computational time is increased due to slowing down of the sampling
frequency resulting from the higher complexity of the IC algorithm is very complexity algorithm
than the P and O has simplicity in algorithm.

The cost of IC method is high since it requires the more accessories (sensors, comparators,
digital circuits etc.,) than P and O method cost is low.
Table 1: The advantages and disadvantages of Incremental Conductance method
Specification
Incremental conductance
Efficiency
High about 98%
Complexity
Difficult
Realization
More complex
Cost
High cost
Reliability
Accurate
Rapidly changing atmosphere
Good and automatically adjusts modules operating voltage
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SHILPA C, S. ZABIULLAH, Dr. VENUGOPAL. N
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.com March 2015, Volume 3 Special Issue, ISSN 2349-4476
IV.
INCREMENTAL CONDUCTANCE ALGORITHM
The incremental conductance method is based on the fact that the slope of the PV array power curve
is zero at the MPP also positive on the left of the MPP and negative on the right, as given by the
following equation and corresponding characteristics is shown in “Figure 3”
= 0, at MPP
> 0, left of MPP
< 0, right of MPP
=
=I+V*
=I+V*
When the maximum power point reached the slope
I+V*
= 0. Thus the condition would be;
=0
=0
=The PV array terminal voltage can be adjusted relative to the MPP voltage by measuring incremental
conductance (I/V) and instantaneous conductance (ΔI/ΔV). Once the MPP is reached, the operation
of the PV array is maintained at this point unless a change in ΔI is noted.
In case of
> 0, the voltage is increased and in case of
< 0, the voltage is decreased to select the
Maximum Power Point. Incremental conductance locates maximum power when the incremental
conductance equal to the negative of instantaneous
conductance. The incremental conductance uses a
search technique that changes the reference or duty
ratio. So the PV panel voltage VPV changes searches
for the condition of the equation and in the condition
the maximum power point is found and searching will
stop. Flow chart of incremental conductance algorithm
is shown in “Figure 4”
Fig: 3 Power - Voltage curve of PV system
Fig: 4 Flow chart of Incremental
Conductance MPPT Algorithm.
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SHILPA C, S. ZABIULLAH, Dr. VENUGOPAL. N
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.com March 2015, Volume 3 Special Issue, ISSN 2349-4476
V.
SIMULINK MODELLING OF SOLAR POWER CONVERTER
The simulation of the solar power converter circuit is done using MATLAB software. The simulation
circuit consists of two parts, one is power converter system and another is the Incremental
Conductance method of MPPT control circuit. The simulated circuit of solar power converter system
is shown as in “Figure 5” and the gate pulse generation to the operation of MOSFET drive shown in
“Figure 6”.
Fig: 5 Simulation Model of power converter
Fig.6 Generation of gate pulses to MOSFET drive controller by the MPPT algorithm.
VI.
SIMULATION RESULTS
Simulation modelling of the high solar power converter with MPPT controller has been done.
Simulation results of required performance of the system in the form of voltage and current
waveforms.
Fig. 7 DC Voltage Output
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SHILPA C, S. ZABIULLAH, Dr. VENUGOPAL. N
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.com March 2015, Volume 3 Special Issue, ISSN 2349-4476
The “Figure 7” shows the output voltage of high step-up boost converter. The DC voltage of solar
power converter from a low value input voltage from a solar panel.
Fig
Fig: 8 Gate Pulse of MOSFET drive.
These pulses are generated from the MPPT INC algorithm; the periodic time varies with respect to
the two parameters of PV panel is shown in “Figure 8”
VII. CONCLUSION
The high step-up boost converter uses the coupled inductor with an appropriate turns ratio design and
switched-capacitor technology to achieve a high-voltage gain that is 20 times higher than the input
voltage. Because the leakage inductance energy of a coupled inductor is recycled and the voltage
stress across the active switch S1 is constrained, the low RDS (ON) of active switch can be selected to
improve maximum efficiency up to 96.7%. As a result, full load efficiency reaches 92.8%. To
minimize the fluctuations and intermittent problems power electronic devices are viable options.
Further, energy storage and use of dump load and MPPT could be used for reducing the power
fluctuations in PV systems. The highest MPPT accuracy is 99.9% and the highest average accuracy
is 97.9% at PPV = 150 W. A 300W solar power optimizer with a high step-up voltage gain and MPP
functions are implemented and verified.
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