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MAXIMUM POWER POINT TRACKING OF SOLAR PANELS USING SEPIC CONVERTER SUBMITTED BY: M.GANESH. S.SIVAKUMAR. K.DEVARAJ. A.RAJKUMAR. GUIDED BY:

Maximum Power Point Tracking of Solar Panels Using Sepic Converter

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Page 1: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

MAXIMUM POWER POINT TRACKING OF SOLAR PANELS USING SEPIC CONVERTER

SUBMITTED BY:

M.GANESH. S.SIVAKUMAR.

K.DEVARAJ. A.RAJKUMAR.

GUIDED BY:

Mr. S.BALAKRISHNAN M.E

Page 2: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

TITLE DESCRIPTION:

Solar power is an alternative technology that will hopefully lead

us away from our

Petroleum and coal dependent energy sources. The major problem

with solar panel technology is that the efficiencies for solar power

systems are still poor and the costs per kilo-watt-hour (kW/h) are not

competitive, in most cases, to compete with petroleum energy

sources. Solar panels themselves are quite inefficient (approximately

30%) in their ability to convert sunlight to energy. However, the charge

controllers and other devices that make up the solar power system are

also somewhat inefficient and costly.

Our goal is to design a Maximum Power Point Tracker (MPPT), a

specific kind of charge controller that will utilize the solar panel to its

maximum potential. The MPPT is a charge controller that compensates

for the changing Voltage vs. Current characteristic of a solar cell. The

MPPT fools the panels into outputting a different voltage and current

allowing more power to go into the battery or batteries by making the

solar cell think the load is changing when you really are unable to

change the load. The MPPT monitors the output voltage and current

from the solar panel and determines the operating point that will

deliver that maximum amount of power available to the batteries.

If our version of the MPPT can accurately track the always-

changing operating point where the power is at its maximum, then the

efficiency of the solar cell will be increased. There are many different

applications for solar power systems, but there are also many

limitations to these applications. The cost-benefit is too low for solar

power systems to be widely used for powering homes, businesses, or

even individual products. Solar power systems are used as the main

Page 3: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

power source for a large majority if not all of the satellites that orbit

the earth. However, the benefit of utilizing solar power in space far

outweighs the cost to implement them.

There are wide ranges of different products available to the

consumer that are solar powered, but they can be expensive or

impractical because of their limitations. Solar power systems are not

competitive on the market because consumers are familiar with the

practical, more convenient products that have more common power

sources that they are used to. Some consumer products are radios,

flashlights, motor-home trickle charging systems, outdoor solar

lighting, and laptop charging systems, and even home systems that

can be tied to their existing power grid. Some of the more practical

applications are used for remote locations such as cabins or small

villages that are located far from the closest power grid.

As a result, the cost to install a solar power system is cheaper

than the cost to send transmission lines from the power grid. Solar

powered systems are also very convenient in small applications such

as powering calculators, outdoor lighting, and even traffic lights. By

attempting to make solar panel systems more efficient altogether,

solar powered products could be used more commonly. While solar

panels are not very efficient due to their current limitations, we hope

to extract the maximum amount of possible power from the solar panel

with our MPPT device. This is just one aspect of making solar power

more efficient.

The actual manufacturing of solar panels is important and is not

something that we are able to take on in this project. There are many

important factors that determine the amount of power the solar panels

can extract from the sun including temperature, time of year,

Page 4: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

geographic location, and positioning of the sun. These factors can be

minimized by designing a proper system that can monitor the output of

the solar cell and extract the maximum amount of possible power from

the solar panels. In order to enable us to complete this project in an

effective manner we need to understand the solar technology and the

most important aspects of it. We will look at different applications and

whether or not they are even feasible at the current state of solar

technology. After understanding more about the technology that solar

power involves and the different applications that it is used for, we can

then approach our problem for a specific application and design the

best solar panel peak power tracking system.

Page 5: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

BLOCK DIAGRAM:

The basic block diagram of the system is shown in Figure

The solar panel will feed the SEPIC converter directly which

stores the electrical energy temporarily in an inductor and then

charges the battery. The battery then feeds the load during sunlight

hours as well as nighttime. The SEPIC converter is to be operated by a

controller. The controller will monitor the voltage and current levels

coming from the solar cell and controls the SEPIC converter

accordingly. While not shown, all active components controller will be

getting its power from the solar cell.

SEPIC CONVERTER DESCRIPTION:

The SEPIC converter is one of the most important components to

the Maximum Peak Power Tracker. To achieve maximum power from

the solar panels, we must operate the panels at their optimum power

point. By opening or closing a switch, the output of the solar panel will

either be shorted or open circuited. The switch discussed will actually

be a MOSFET. The controller will control this MOSFET. To understand

the SEPIC converter, the MOSFET is modeled with a simple ideal switch.

The switch, U1, will open and close to control the voltage level over the

SOLAR PANEL

SEPIC CONVERTER BATTERY

CONTROL CIRCUIT

Page 6: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

inductor, which will essentially set the solar panels to their optimum

power level. The SEPIC converter is shown in Figure with the solar

panel shown as a voltage source Vs. More accurate representations of

the solar panel will be used shortly.

L1 + Vc- - Vd + I1

Io

R +

Vi S L2 I2

Vo

As the switch is closed the voltage drops as the current increases towards its

maximum short circuit current. If the switch is closed for a long enough period of time

the voltage will eventually drop to zero and thus the power at this point is zero. If the

switch is open, the voltage will rise to its open circuit voltage and no current flows out of

the solar panel. Again the power will be zero watts. Due to the inductor’s presence in the

SEPIC converter, current and voltage transients will not happen instantly but instead take

some time. Therefore the power cannot instantly move from optimum to zero, but instead

takes some time constant. By opening and closing this switch at fast speeds, it is possible

to pick a place such as the peak power point and operate close to this point. The

equivalent circuit of the solar panel is shown in the figure.

rg converter

Solar Panel

+ vi ri Load

vg

-

Page 7: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

FUNCTION DESCRIPTION:

The input resistance of the converter and the output resistance of the

solar panel is matched by feeding the both signals to the error amplifier

The error amplifier in the control circuit compares the maximum input

ripple voltage and the attenuated switch voltage stress and generates error

signal the error signal is then superimposed with a small signal Sinusoidal

perturbation which produces the combined drive signal Vcon.

The combined signal Vcon is compared to a ramp function to generate

a PWM gate signal to the main switch the error amplifier generates a signal

so as to increase or decrease the duty cycle w.r.t input and output resistance

values of the inverter and panel

The regulatory actions cause the feedback network to adjust the duty

cycle in order to make equal of input and output resistance of converter and

solar panel Trance of converter and solar panel

Page 8: Maximum Power Point Tracking of Solar Panels Using Sepic Converter

ADVANTAGES:

Simple and elegant technique.

It doesn’t need any mathematical calculation.

No need of output sampling and digital signal processing.

It can be used in various meteorological condition.

APPLICATION:

Used in solar street light light traction.

Used in aero space industries.

Used in communication equipments.

Used as a power supply controller in remote areas.