DAB report for FYP

To Design, Simulate and fabrication of Transformer less and Battery less Solar Inverter with Voltage Regulation

2 | P a g e

NATIONAL UNIVERSITY OF SCIENCES ANDTECHNOLOGY

Project Members Luqman Ahmed EE-804

Syed Usama Hassan EE-803

Chaudry Asad ur Rehman EE-788

Project Advisor A/P Muhammad Farhan.

PAKISTAN NAVY ENGINEERING COLLEGE

Department of Electrical and Power Engineering

3 | P a g e

4 | P a g e

Contents

General Idea:.............................................................................................8

Goals.........................................................................................................9

Impact.....................................................................................................10

Introduction............................................................................................11

Limitations of Batteries:.........................................................................................................................11

Limitations of Transformers:.................................................................................................................14

Block / System Flow Diagram:.................................................................15

Solar Panels:............................................................................................16

Types of solar cells.............................................................................................................................16

Mono Crystalline Solar Cell:...................................................................................................................17

Poly Crystalline Solar Cell:.....................................................................................................................18

Hybrid Panels.........................................................................................................................................18

Black Frames and Black Backed Panels:.................................................................................................18

Voltage Regulator:...................................................................................21

Buck Converter:.........................................................................................................................................21

The Buck Converter........................................................................................................................21

Transistor Switch ‘on’ Period.................................................................................................................23

Switching Transistor ‘on’ Period....................................................................................................23

Transistor Switch ‘off’ Period:................................................................................................................24

Switching Transistor ‘off’ Period....................................................................................................24

Buck Converter for Negative Supplies:..................................................................................................24

Schematic Diagram:...............................................................................................................................26

...............................................................................................................................................................26

Circuit Diagram:.....................................................................................................................................27

Buck Regulator Flowchart....................................................................................................................28

CALCULATIONS FOR BUCK REGULATOR:...............................................................................................29

RESULT TABLE :......................................................................................................................................30

5 | P a g e

Program for BUCK REGULATOR:............................................................................................................31

Inverters:.................................................................................................. 1

Introduction:............................................................................................................................................1

Input Voltage:..........................................................................................................................................1

Output Waveform:..................................................................................................................................1

Square wave:...........................................................................................................................................2

Sine Wave:...............................................................................................................................................2

Modified Sine Wave................................................................................................................................3

Output Frequency:..................................................................................................................................4

Basic Design:............................................................................................................................................5

Inverter Block Diagram..........................................................................................................................6

Isolators:......................................................................................................................................................7

Why we preferred IGBTs over MOSFET:..................................................................................................7

Output frequency................................................................................................................................9

Output power......................................................................................................................................9

Program:................................................................................................................................................10

Inverter Schematic:...............................................................................................................................13

...............................................................................................................................................................13

Inverter Output: ....................................................................................................................................14

...............................................................................................................................................................15

Gantt Chart..............................................................................................16

Benefits and Beneficiaries.......................................................................18

Project Risk Assessment..........................................................................19

Financial Details of The Project................................................................21

6 | P a g e

7 | P a g e

General Idea:Energy disaster has become a main worry in the current age day engineering sciences. More and

more thoughts are imminent in the market to over handle the power shortfall. More tasks are piling up for the respective administrations to answer the need of hour. In spite of of several pains by the engineers, technicians and the managements in this respect, energy calamity doesn’t appear likely to be controlled. This has shaped very disturbing state for our future generations.

It is the right time to search the alternatives ways to address the need of the hour. The main necessity of the corporations and firms is the nonstop and continual power source to the load. Another alarm in this regard is the price of the energy being consumed by the consumer. Everyone desires less costly electricity. Straight sources for power generation have so far been very ineffective to deliver the desired results. Therefore, people are now thoughtful of moving towards unusual energy sources e.g. solar energy (with the help of Solar Panels), wind energy (with the help of Wind Turbines) and chemical energy (with the help of Fuel Generators).

In our designed project, we have intended to design a battery-less high voltage transformer less solar inverter with input high voltage regulator. This project, as we desire, will be very cost effective as well as well-organized to meet the essentials of the hour. Using our earlier knowledge along with the familiarity gained during the theory classes, we’ll be able to present a solid engineering masterwork that’d be able to provide continuous supply of power without any pause without using the conventional batteries or transformers.

8 | P a g e

GoalsThe key purpose of building this project this project is to give a customized solution to the energy needs of the modern times using new ideas safeguarding the continuous and constant supply of electricity without using battery and transformer. This project will be able to give maximum performance with minimum expenses and worry. Our project will have these features:

1. It will be capable of giving constant supply of power at the output using solar energy with the practical usage of buck-boost regulator. We, in this project, will be showing the integrated circuit of buck-converter (step-down) and boost-converter (step-up).

2. Our project will be very unresponsive to the changing input voltage and irrespective of input varying voltage; we’ll be having same voltage at the output.

3. By having 311V DC inverted we can have 220V AC at the output that can be easily used for the home appliances.

4. Due to the passive behavior towards the changing sunlight (input voltage), we’ll be able to overcome the deficiency of batteries. We’ll already be working on high voltages so there’ll be no need of using transformer to step-up the voltage.

9 | P a g e

ImpactOur project would be able to perform the least expensive operation ever. It not only ensures the effectiveness of cost but also it is an introduction of idea about buck-boost regulator in Pakistan that has not been really done so far. This novelty in the field of engineering is hoped to bring good changes.

Enlargement and application of our planned project would not only give the investigators and students a chance to go in depth about the study and visualization of the modern concepts of power engineering, but also demonstrate a very dynamic part in founding a durable base to permit the power engineering industry of the Pakistan to grow important models and services in its imperative research in the inverters, regulators and converters. It will let the Engineers all across Pakistan to think about same sort of idea on a larger scale. These phases, if accomplished, would provide us a path on walk on for the further development of renewal energy sources with least environment damage (as it takes place in the case of biogas and some others). Also it will enable Pakistan to stand on a solid ground with respect to engineering.

10 | P a g e

Introduction

Because of increase prices of electrical equipment and instruments, it has very difficult for everyone to buy batteries after batteries. So is the case with transformers. We have some reasonable list of the reasons why batteries are so unpleasing to us.

Limitations of Batteries:In this section, we’ll try to elaborate why batteries are not preferable to be used. By reading this, the benefits and advantages of a battery-less system will be cleared.

1- Non-rechargeable batteries (primary, dry cell) are the most commonly used domestic batteries. They are frequently used in torches, toys, smoke detectors, watches, calculators, hearing aids, radios and remote controls and a lot of other appliances of same sort. This type of battery cannot be recharged after use and, although they can be recycled, battery recycling programmes and facilities are still developing and they still need a lot of efforts along with modification to maintain all the stuff that is simply dumped and thrown out as a trash, so maximum primary batteries are just thrown away when they become ‘flat’.

11 | P a g e

Fig.1 Flat Batteries

2- Batteries have a limited life. They constantly need to be recharged or replaced. Even rechargeable batteries have a limited life and must eventually be replaced.

3- Usage of batteries makes the equipment heavier and thus it becomes very difficult to use them. This usually happens with high power consuming equipment. So we prefer a system that doesn’t have a battery.

4- Usage of batteries needs a lot of maintenance and continuous watch. They also need to be checked periodically. It could also cause the wastage of a lot of our precious time.

5- Some batteries are very dangerous to the living things and they pose danger to almost everything around them.

6- Explosion of eruption cases of batteries have already a lot of damage to the common people as well as researchers.

12 | P a g e

Fig.27- Batteries can also catch fire because of chemical and electrical changes going on in them

as well because of the fuel or acid inside them.

Fig.3

13 | P a g e

Limitations of Transformers:

1- Transformers are usually costly and thus they make our product more expensive.2- They, like batteries, are heavier and make it difficult for us to handle the operation

sometimes.3- In three-phase transformers, there is a greater cost of stand by units.4- Inconvenience of repairs is also a main disadvantage of transformers.5- In case of 3-phase transformer, if one of three phases goes out of order, other two also

stop working properly.6- A transformer less system requires less space so it is more easy to use.7- Presence of a transformer makes the system require more time for assembling.8- A transformer less system is easier to install.9- Hysteresis Ploss ~ f that arises from magnetic poles in the core material being aligned

causes a lot of power wastage.10- Eddy current that arises in the magnetic core because of varying flux.11- Instrument transformers cannot be used for DC measurements.12- Auto transformers have low impedance therefore they have high short circuit currents

for short circuits on secondary side. If a section of winding in auto transformers common to primary and secondary gets opened, full primary voltage will appear across the secondary resulting in higher voltage on secondary and danger of accidents. Moreover, there is no electrical separation between primary and secondary which is risky in case of high voltage levels.

14 | P a g e

Block / System Flow Diagram:

Solar panels connected in series (22 panels)

Voltage Regulator

(320V DC)

Transformer less inverter

311 DC 220 AC

Load

15 | P a g e

Solar Panels:

1 Types of solar cells

Basically Solar cells are of four types

1- mono crystalline solar cell 2- Poly crystalline solar cell 3- All black and 4- Hybrid

16 | P a g e

Mono Crystalline Solar Cell:

As it is obvious from its name, its one cell composed of one silicon crystal. It is usually black in color. It works in dim light and is very sensitive and expensive in all solar cells. It converts 18% of the incident light into electricity.

It has low beat bearing capacity and shows its complete efficiency till temperature ranges to25C. Temperature varies for different solar cells. It is written on all solar cells as N.O.T.C (Nominal Operating Cell Temperature).

In mono crystalline solar cell, if some of its silicon cells are exposed to light while at the same time the others are not then it may cause damaging of the solar panel. It is therefore should be kept in mind that at the same time all the cells must be exposed to light or be kept in dark.

17 | P a g e

Poly Crystalline Solar Cell:

It’s one cell composed of multiple silicon crystal. It is usually blue in color and there may be spots or lines of other colors seen in the cell.

It converts 15% of the incident light into electricity. If we compare it with the same size of mono crystal solar cell then its efficiency is slightly lower than the mono crystal solar cell.

It is also somehow lesser sensitive and less expensive than mono crystalline solar cell. Its heat bearing capacity is more than mono crystalline cell. It usually works under the temperature ranges to 45C but it also varies for different solar panels. As in mono crystalline solar cell, at the same time some part of it in dark and some part exposed to light cause damaging of cell.

Hybrid Panels

The main manufacturer of hybrid panels is Panasonic (formerly Sanyo). Their HIT module which has a thin layer of amorphous solar film behind the monocrystalline cells. The extra amorphous layer extracts even more energy from the available sunlight, particularly in low light conditions. These are the most efficient panels available, so they take up the least space on your roof.

Black Frames and Black Backed Panels:

For some reason in our crazy UK market, many people are now offering completely black panels, not only with black frames, but also with a black backing behind the cells instead of the traditional white. It is true that these do give a much better appearance, particularly on slate roofs or old traditional cottages with dark colored plain tiles.

NOTE: Hybrid and Black Backed Panels are not available in Pakistan.

18 | P a g e

Solar Panel in Our Project:

We, in our project, will use mono-crystalline type of solar panels.

Mono crystalline Solar Panels

Mono crystalline photovoltaic electric solar energy panels have been the go-to choice for many years. They are among the oldest, most efficient and most dependable ways to produce electricity from the sun.

Benefits of Mono crystalline Solar Panels:

Determining what is an advantage or a benefit is a relativistic exercise and in this case the base of reference is the other types solar panel technologies. With this caveat in mind, here are the good reasons why many people choose mono crystalline solar technology:

Longevity:

Mono crystalline solar panels are first generation solar technology and have been around a long time, providing evidence of their durability and longevity. The technology, installation, performance issues are all understood. Several of the early modules installed in the 1970's are still producing electricity today. Single crystal panels have even withstood the rigors of space travel!

Some other solar websites suggest that single crystalline solar panels can last up to 50 years. Most performance warranties go for 25 years, but as long as the PV panel is kept clean it will continue to produce electricity.

Efficiency:

As already mentioned, PV panels made from mono crystalline solar cells are able to convert the highest amount of solar energy into electricity of any type of flat solar panel. Consequently, if your goal is to produce the most electricity from a specific area (e.g., on a roof) this type of panel should certainly be considered.

Greater Heat Resistance:

19 | P a g e

Like other types of solar panels, mono crystalline solar modules suffer a reduction in output once the temperature from the sunlight reaches around fifty degrees Celsius/a hundred and fifteen degrees Fahrenheit. Reductions of between 12-15 percent can be expected. This loss of efficiency is lower than what is typically experienced by owners of PV panels made from polycrystalline cells.

More Electricity:

Besides producing more electricity per sqm of installed panels, thereby improving your cash flow (from either a reduction in your electrical bill or from the sale of the electricity or in some areas both), for those who are "going green" and are concerned about the environmental impact of solar panels, mono crystalline panels reduce the amount of electricity needed from local power plants, reducing the dependence on fossil fuels.

Bankability:

A corollary of the durability and longevity of this type of solar panels is that in areas where there is an established track record of performance, we are able to obtain bank financing of up to 90% for our projects, which is certainly a big reason why Germany has the largest installed base of solar panels in the world.

Disadvantages of Mono crystalline Solar Panels:

Initial Cost:

Because PV panels made from single-cell silicon crystals the process of making them is one of the most complex and costly ones around. Good silicon feedstock is expensive.

Fragile:

Generally, the solar panels are covered by a safety glass that helps protect the panels from damage, but if you are in an area where you are likely to experience roof damage due to falling / flying objects besides the obvious of making sure your solar installation is insured at replacement value.

20 | P a g e

Voltage Regulator:

Buck Converter:

Fig. 4.The Buck Converter

The step-down dc–dc converter, usually branded as a buck converter, is presented in Fig. 4.6

(a). It involves dc input voltage source VS , controlled switch S, diode D, filter inductor L, filter

capacitor C, and load resistance R. Characteristic waveforms in the converter are displayed in

Fig.4.7 (b) under supposition that the inductor current is permanently positive. The state of the

converter in which the inductor current is not ever zero for any period of time is usually called

the continuous conduction mode (CCM). It can be understood from the circuit that when the

switch S is directed to the on state, the diode D gets reverse biased.

When the switch S is off, the diode conducts to assist a continuous current supply in the

inductor. The link among the input voltage, output voltage, and the switch duty ratio D can be

derived, for instance, from the inductor voltage vL waveform (see Fig 4.7(b)).

21 | P a g e

Giving to Faraday’s law, the inductor volt–second product over a period of steady-state

operation is zero. For the buck converter value of the inductor can be calculated with help of

following way;

L = VaD / f ΔI Vs Equation (3)

Similarly the value of the capacitor can be found out as;

C = ΔI / 8f ΔVc Equation (4)

The dc–dc converters are able to work in two different ways with respect to the inductor current

iL. Figure 4.7(b) tells the CCM in which the inductor current is always greater than zero. When the

average value of I/P current is less (high R) and/or the switching frequency f is low, the converter

might enter the discontinuous conduction mode (DCM). In the DCM, the inductor current is zero

during a part of the switching time. The CCM is always chosen by us for the highest efficiency and

good utilization of semiconductor switches and passive components. The DCM can also be used

in applications with its special control requirements; as the dynamic order of the converter is

reduced (the energy kept in the inductor is as zero at the beginning and at the end of each

switching period).

The filter inductor current iL in the CCM contains a dc component Io with a overlaid triangular ac

component. Nearly this complete ac component streams through the filter capacitor as a current

ic. Current ic causes a small voltage ripple crossways the dc output voltage Vo. To limit the peak-to-

peak value of the ripple voltage under a specific value Vr, the filter capacitance C has to be

greater than

Equations (3) and (4) are the main project equations for the buck converter’s operation. The

input & output dc voltages (thus the duty ratio D), and the work range of load resistance R are

usually found out by opening stipulations. The designer is required to have calculated the values

of passive components L and C, and of the switching frequency f. The value of the filter inductor L

is usually calculated with the help of Eq. (3).

22 | P a g e

The assessment of the filter capacitor C is got from the voltage ripple condition Eq. (4). Meant for the compactness and low conduction losses of a converter, it is appropriate to practice small passive components. Equations (3) and (4) are clearly showing that it can be done with using a high switching frequency f. The switching frequency is narrow, however, by the type of semiconductor switches used and by switching losses. It should be also noticed that the values of L and C can be changed by effects of biting components in the converter, especially by the alike series resistance of the capacitor.

Transistor Switch ‘on’ Period

Fig. 5 Switching Transistor ‘on’ Period

In Fig. 5 therefore, when the switching transistor is switched on, it is supplying the load with current. Initially current flow to the load is restricted as energy is also being stored in L1; therefore the current in the load and the charge on C1 builds up gradually during the ‘on’ period. Notice that throughout the on period, there will be a large positive voltage on D1 cathode and so the diode will be reverse biased and therefore play no part in the action.

23 | P a g e

Transistor Switch ‘off’ Period:

Fig. 6 Switching Transistor ‘off’ Period

Buck Converter for Negative Supplies:

For negative supplies the circuit shown in Fig. 7 can be used. This involves a change around in the positions of L1 and D1, and reversing the polarity of C compared to the circuit in Fig 5. This variation of the basic buck converter now inverts the positive DC input to produce a negative supply in the range of 0V to −VIN.

Fig. 7

When the transistor switches off as shown in Fig 6 the energy stored in the magnetic field around L1 is released back into the circuit. The voltage across the inductor (the back

24 | P a g e

e.m.f.) is now in reverse polarity to the voltage across L1 during the ‘on’ period, and sufficient stored energy is available in the collapsing magnetic field to keep current flowing for at least part of the time the transistor switch is open.

The back e.m.f. from L1 now causes current to flow around the circuit via the load and D1, which is now forward biased. Once the inductor has returned a large part of its stored energy to the circuit and the load voltage begins to fall, the charge stored in C1 becomes the main source of current, keeping current flowing through the load until the next ‘on’ period begins.

The overall effect of this is that, instead of a large square wave appearing across the load, there remains only a ripple waveform, i.e. small amplitude, high frequency triangular wave with a DC level of:

VOUT = VIN x (On time of switching waveform (tON) / periodic time of switching waveform( T))

or:

Therefore if the switching waveform has a mark to space ratio of 1:1, the output VOUT from the buck Converter circuit will be VIN x(0.5/1) or half of VIN. However if the mark to space ratio of the switching waveform is varied, any output voltage between approximately 0V and VIN is possible.

25 | P a g e

Schematic Diagram:

26 | P a g e

Circuit Diagram:

27 | P a g e

Buck Regulator Flowchart

DC Input

320 400V DC

Controller ADC compared with

320V DC (Desired)

Controller

Buck Converter

Desired output

DC (320V)

Generate PWM for desired voltage

Output

28 | P a g e

CALCULATIONS FOR BUCK REGULATOR:

Input voltage

Vs = 400 v

Output voltage

Vo = 320 v

Ripple voltage

ΔVc= 20v,

Frequency of the switching device

f =43.2 kHz,

Change in current

ΔI =36A,

Duty cycle

D =0.8

For Inductor:

L = VaD / f ΔI Vs

L = 320(0.8) / (43.2k×36×400)

L = 0.41 uH

29 | P a g e

For Capacitor:

C = ΔI / 8f ΔVc

C = 36 / (8×43.2k×20)

C = 5.2 uF

RESULT TABLE :

DUTY CYCLE

(%)

FREQUENCY

KHz

O/P (DC)

V

I/P (DC)

V

20 43.2 220 140

30 43.2 220 158

40 43.2 220 172

50 43.2 220 177

60 43.2 220 178

70 43.2 220 189

80 43.2 220 193

30 | P a g e

Program for BUCK REGULATOR:

#include <mega16.h>

#include <delay.h>

#include <ATKv10_1.h>

void main(void)

{

unsigned char spoint=200;

unsigned char newADC;

PORTB=0xFF;

DDRB=0xFF;

PORTC.0=1;

PORTC.1=1;

TCCR0=0x6D;

OCR0=128;

Init_LCD( );

ADCSRA.ADEN=1;

wrLCDcmd(0x80);

LCD_msg(" BUCK CHOPPER ");

delay_ms(2500);

wrLCDcmd(0x01);

while (1)

{

newADC=GetADCdata(0);

wrLCDcmd(0x80);

LCD_msg("newADC: ");

if(newADC > spoint)

{

OCR0--;

}

else

{

OCR0++;

};

UpdateDigits (new ADC);

wrLCDcmd (0xc0);

LCD_msg ("OCR0: ");

UpdateDigits (OCR0);

delay_ms (500);

}

}

31 | P a g e

Inverters:

Introduction:A power inverter, or inverter, is an electronic device or circuitry that changes direct current DC to alternating current AC

The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source.

Input Voltage:A typical power inverter device or circuit requires a relatively stable DC power source capable of supplying enough current for the intended power demands of the system. The input voltage depends on the design and purpose of the inverter. Examples include:

12 VDC, for smaller consumer and commercial inverters that typically run from a rechargeable 12V lead acid battery.

24 and 48 VDC, which are common standards for home energy systems.

200 to 400 VDC, when power is from photovoltaic solar panels.

300 to 450 VDC, when power is from electric vehicle battery packs in vehicle-to-grid systems.

Hundreds of thousands of volts, where the inverter is part of a high voltage DC power transmission system.

Output Waveform:An inverter can produce a square wave, modified sine wave, pulsed sine wave, or sine wave depending on circuit design. The two dominant commercialized waveform types of inverters as of 2007 are modified sine wave and sine wave.

32 | P a g e

There are two basic designs for producing household plug-in voltage from a lower-voltage DC source, the first of which uses a switching boost converter to produce a higher-voltage DC and then converts to AC. The second method converts DC to AC at battery level and uses a line-frequency transformer to create the output voltage.

Square wave:This is one of the simplest waveforms an inverter design can produce and is useful for some applications.

Fig. 5.1 Square wave

Sine Wave:A power inverter device which produces a multiple step sinusoidal AC waveform is referred to as a sine wave inverter. To more clearly distinguish the inverters with outputs of much less distortion than the "modified sine wave" (three step) inverter designs, the manufacturers often use the phrase pure sine wave inverter. Almost all consumer grade inverters that are sold as a "pure sine wave inverter" do not

33 | P a g e

produce a smooth sine wave output at all, just a less choppy output than the square wave (one step) and modified sine wave (three step) inverters. In this sense, the phrases "Pure sine wave" or "sine wave inverter" are misleading to the consumer. However, this is not critical for most electronics as they deal with the output quite well.

Where power inverter devices substitute for standard line power, a sine wave output is desirable because many electrical products are engineered to work best with a sine wave ac power source. The standard electric utility power attempts to provide a power source that is a good approximation of a sine wave.

Sine wave inverters with more than three steps in the wave output are more complex and have significantly higher cost than a modified sine wave, with only three steps, or square wave, (one step), types of the same power handling. Switch-mode power supply (SMPS) devices, such as personal computers or DVD players, function on quality modified sine wave power. AC motors directly operated on non-sinusoidal power may produce extra heat, may have different speed-torque characteristics, or may produce more audible noise than when running on sinusoidal power

Fig. 5.2 Sine wave

Modified Sine WaveA "modified sine wave" inverter has a non-square waveform that is a useful rough approximation of a sine wave for power translation purposes.

The waveform in commercially available modified-sine-wave inverters is a square wave with a pause before the polarity transition, which only needs to cycle

34 | P a g e

through a three-position switch that outputs forward, off, and reverse output at the pre-determined frequency. Switching states are developed for positive, negative and zero voltages as per the patterns given in the switching Table 2. The peak voltage to RMS voltage does not maintain the same relationship as for a sine wave. The DC bus voltage may be actively regulated or the "on" and "off" times can be modified to maintain the same RMS value output up to the DC bus voltage to compensate for DC bus voltage variation.

The ratio of on to off time can be adjusted to vary the RMS voltage while maintaining a constant frequency with a technique called PWM. The generated gate pulses are given to each switch in accordance with the developed pattern and thus the output is obtained. Harmonic spectrum in the output depends on the width of the pulses and the modulation frequency. When operating induction motors, voltage harmonics are not of great concern; however, harmonic distortion in the current waveform introduces additional heating and can produce pulsating torques.

Numerous electric equipment will operate quite well on modified sine wave power inverter devices, especially any load that is resistive in nature such as a traditional incandescent light bulb.

Most AC motors will run on MSW inverters with an efficiency reduction of about 20% due to the harmonic content. However, they may be quite noisy. A series LC filter tuned to the fundamental frequency may help.

Output Frequency:The AC output frequency of a power inverter device is usually the same as standard power line frequency, 50 or 60 hertz

If the output of the device or circuit is to be further conditioned (for example stepped up) then the frequency may be much higher for good transformer efficiency.

35 | P a g e

Basic Design:In one simple inverter circuit, DC power is connected to a transformer through the center tap of the primary winding. A switch is rapidly switched back and forth to allow current to flow back to the DC source following two alternate paths through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternating current (AC) in the secondary circuit.

The electromechanical version of the switching device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against one of the stationary contacts and an electromagnet pulls the movable contact to the opposite stationary contact. The current in the electromagnet is interrupted by the action of the switch so that the switch continually switches rapidly back and forth. This type of electromechanical inverter switch, called a vibrator or buzzer, was once used in vacuum tube automobile radios. A similar mechanism has been used in door bells, buzzers and tattoo machines.

As they became available with adequate power ratings, transistors and various other types of semiconductor switches have been incorporated into inverter circuit designs. Certain ratings, especially for large systems (many kilowatts) use thyristors (SCR). SCRS provide large power handling capability in a semiconductor device, and can readily be controlled over a variable firing range.

The switch in the simple inverter described above, when not coupled to an output transformer, produces a square voltage waveform due to its simple off and on nature as opposed to the sinusoidal waveform that is the usual waveform of an AC power supply. Using Fourier analysis, periodic waveforms are represented as the sum of an infinite series of sine waves. The sine wave that has the same frequency as the original waveform is called the fundamental component. The other sine waves, called harmonics,that are included in the series have frequencies that are integral multiples of the fundamental frequency.

36 | P a g e

Inverter Block Diagram

Controller

Isolator / Optocoupler

Driver IC

IGBTS

Output

37 | P a g e

Isolators:The HCPL-2530 optocouplers consist of an AlGaAs LED optically coupled to a high speed photo detector transistor. Optocouplers will be used as isolators. Isolation is necessary to separate the control circuit operating at digital voltages from the inverter circuit operating at high voltages.While selecting proper isolators, it is made sure that the selected optocouplers are able to handle the required operating voltages and high frequency signals.Features of HCPL-2530 are listed as following.

High speed -1 Mbit/s Superior CMRR-10 kV/1e-6s Dual-Channel with single supply Double working voltage – 480V RMS Operating temperature range 0-70 degree Celsius

The isolator configuration of the project developed in three phase configuration.Dual channel allows each phase to have its own independent isolator.The inputs are connected to the DSC’s PWM outputs, sharing the same ground that of control electronics.The outputs are connected to the logic side of IR2112 gate driving chips consequently referenced to its logic ground.Pull-up resistors are placed at the output, inverting the isolated input signal.This inversion has been taken care of in the DSC fuse settings.The outputs are driving the logic side of gate drivers.Inputs are configured in the current sourcing mode with a current limiting resistor of 470 Ohms allowing a maximum current of 10mA at logic high of 5V from the controller.Cathode of each input is tied to digital ground with the anodes connected to the PWM outputs of dsPIC.

Why we preferred IGBTs over MOSFET:

1. IGBTs have improved production techniques, which has resulted in a lower cost

2. IGBTs have improved durability to overloads that also fulfills our many

requirements.

3. IGBTs have improved parallel current sharing

4. IGBTs have faster and smoother turn-on/-off waveforms

5. IGBTs have lower on-state and switching losses

6. IGBTs have lower thermal impedance

7. IGBTs have lower input capacitance

8. It has a very low on-state voltage drop due to conductivity modulation and has

superior on-state current density. So smaller chip size is possible and the cost

38 | P a g e

can be reduced.

9. Low driving power and a simple drive circuit due to the input MOS gate structure.

It can be easily controlled as compared to current controlled devices (thyristor,

BJT) in high voltage and high current applications.

10. Wide SOA. It has superior current conduction capability compared with the

bipolar transistor. It also has excellent forward and reverse blocking capabilities.

Safe Operating Area (SOA)

The safe operating area (SOA) is defined as the current-voltage boundary within

which a power switching device can be operated without destructive failure. For

IGBT, the area is defined by the maximum collector-emitter voltage VCE and

collector current IC within which the IGBT operation must be confined to protect it

from damage. The IGBT has the following types of SOA operations: forward-biased

safe operating area (FBSOA), reverse-biased safe operating area (RBSOA) and

short-circuit safe operating area (SCSOA).

Gate Drivers

The IR2112(S) is a high voltage, high speed power MOSFET and IGBT driver with independent high and low side referenced output channels. Proprietary HVIC and latch immune CMOS technologies enable ruggedized monolithic construction. Logic inputs are compatible with standard CMOS or LSTTL outputs, down to 3.3V logic. The output drivers feature a high pulse current buffer stage designed for minimum driver cross-conduction. Propagation delays are matched to simplify use in high frequency applications. The floating channel can be used to drive an N-channel power MOSFET or IGBT in the high side configuration which operates up to 600 volts.

Features

Floating channel designed for bootstrap operation Fully operational to +600V Tolerant to negative transient voltage dV/dt immune Gate drive supply range from 10 to 20V Undervoltage lockout for both channels 3.3V logic compatible Separate logic supply range from 3.3V to 20V Logic and power ground ±5V offset

39 | P a g e

CMOS Schmitt-triggered inputs with pull-down Cycle by cycle edge-triggered shutdown logic Matched propagation delay for both channels Outputs in phase with inputs

Output frequency

The AC output frequency of a power inverter device is usually the same as standard power line frequency, 50 or 60 hertz

If the output of the device or circuit is to be further conditioned (for example stepped up) then the frequency may be much higher for good transformer efficiency.

Output power

A power inverter will often have an overall power rating expressed in watts or kilowatts. This describes the power that will be available to the device the inverter is driving and, indirectly, the power that will be needed from the DC source. Smaller popular consumer and commercial devices designed to mimic line power typically range from 150 to 3000 watts.

Not all inverter applications are primarily concerned with brute power delivery; in some cases the frequency and or waveform properties are used by the follow-on circuit or device.

40 | P a g e

Program:#include <mega162.h>

#include <delay.h>

#define f 400

#define spc 24

#define adj 6

#define Phase1L PORTC.0

#define Phase1H PORTC.1

flash unsigned char PWMCodes[721]={0,4,9,13,18,22,27,31,35,40,44,49,53,57,62,66,70,75,79,83,87,91,96,100,104,108,112,116,120,124,127,131,135,139,143,146,150,153,157,160,164,167,171,174,177,180,183,186,190,192,195,198,201,204,206,209,211,214,216,219,221,223,225,227,229,231,233,235,236,238,240,241,243,244,245,246,247,248,249,250,251,252,253,253,254,254,254,255,255,255,255,255,255,255,254,254,254,253,253,252,251,250,249,248,247,246,245,244,243,241,240,238,236,235,233,231,229,227,225,223,221,219,216,214,211,209,206,204,201,198,195,192,190,186,183,180,177,174,171,167,164,160,157,153,150,146,143,139,135,131,128,124,120,116,112,108,104,100,96,91,87,83,79,75,70,66,62,57,53,49,44,40,35,31,27,22,18,13,9,4,0,4,9,13,18,22,27,31,35,40,44,49,53,57,62,66,70,75,79,83,87,91,96,100,104,108,112,116,120,124,127,131,135,139,143,146,150,153,157,160,164,167,171,174,177,180,183,186,190,192,195,198,201,204,206,209,211,214,216,219,221,223,225,227,229,231,233,235,236,238,240,241,243,244,245,246,247,248,249,250,251,252,253,253,254,254,254,255,255,255,255,255,255,255,254,254,254,253,253,252,251,250,249,248,247,246,245,244,243,241,240,238,236,235,233,231,229,227,225,223,221,219,216,214,211,209,206,204,201,198,195,192,190,186,183,180,177,174,171,167,164,160,157,153,150,146,143,139,135,131,128,124,120,116,112,108,104,100,96,91,87,83,79,75,70,66,62,57,53,49,44,40,35,31,27,22,18,13,9,4};

void main(void)

{

unsigned char i=0;

DDRA=0x00;

41 | P a g e

DDRB=0x13;

DDRC=0x3F;

DDRD=0x10;

TCCR0=0x6a;

OCR0=0x00;

while (1)

{

for (i=0;i<spc;i++)

{

j=i+8;

k=i+16;

if(i<12)

{

Phase1L=0;

Phase1H=1;

}

else

{

Phase1H=0;

Phase1L=1;

42 | P a g e

}

OCR0=PWMCodes[i*(360/spc)]; // Output Phase#1 (OCR0)

OCR3AL=PWMCodes[(j)*(360/spc)]; // Output Phase#2 (OCR3A)

OCR2=PWMCodes[(k)*(360/spc)]; // Output Phase#3 (OCR2)

delay_us((1000000/(f*spc))-adj);

};

};

}

43 | P a g e

Inverter Schematic:

44 | P a g e

Inverter Output:

45 | P a g e

PRACTICAL WORK AND OUTPUT:

Output with out filter

Output with filter

46 | P a g e

Gantt Chart

47 | P a g e

48 | P a g e

49 | P a g e

Benefits and Beneficiaries

As discussed earlier that this module would have a number of benefits, and so would be very much favorable to be implemented. The direct and indirect benefits and beneficiaries are listed below:

S. No. BENEFITS BENEFICIARIES

1. Serves as a basic module to develop and test more sophisticated control schemes and systems

Research Students / Professionals in this field

2. Demonstration of “Buck-Boost Converter” technology Power Electronics Students/University

3. Introduction of this project/module on commercial Levels

National Electric Supply Companies (WAPDA, KESC etc)

4. Applying this System in “Industries (working at day time)”

Industry people

5. With the usage of our product, we’ll be able to provide constant supply without using conventional batteries.

Consumers

Table 3: Direct and Indirect Benefits with Beneficiaries

50 | P a g e

Project Risk AssessmentA detailed project risk assessment was carried out to take into account any possible events or

scenarios which might cause any hurdle in the safe going of the project and might cause any

unwanted and undesired delay or in worst case the termination of the project. Following three

categories of the risk assessment are catered in the evaluation:

Risk Identification – Identification of the possible potential risks

Risk Assessment – Detailed assessment of the potential risks

Risk Management – Measures proposed for tackling those potential risks

A table was formulated for taking in account all the evaluation of the risk assessment. Following

criteria was established for the risk rating in the table:

RISK LEVELLOW 1

MEDIUM 2

HIGH 3

Table 4: Risk Level Indicator

Here it is also pertinent to mention here that “Risk Rating” is calculated by the product of “Likelihood of Occurrence” & “Impact”. This could be stated in the form of a table as follows:

Risk Rating (Likelihood of Occurrence) x (Impact)

51 | P a g e

Table 5: Risk Rating

The table for the detailed risk assessment of the project is given below:

Sr. No

.

Risk Description Consequences Likelihood Impact Risk Rating

Risk Managemen

t1. Cost If project

cost exceeds the assumed budget

It would have effect on the completion of the project

1 2 2 Complete evaluation of the project plan was considered

2. Safety Equipment failure or arcing

System dead or fire in the system

2 2 4 Proper design of structure and safety measures would be taken

3. Quality If a proper quality in the selection of equipment is not maintained

Low life of the product and the system would be unreliable

2 3 6 Equipment and materials would be properly checked

4. Performance The desired output is not obtained

Projects requirements would not be met

2 3 6 Reliable techniques of equipment analysis would be taken to task

5. Purchasing Unavailability of the equipment required

Delay in project’s submission deadline

1 3 3 Equipment would be purchased as soon as possible to make sure to take in account the state of availability, otherwise equipment could be imported as well

Table : Project Risk Assessment

52 | P a g e

Financial Details of The Project

S. No. EQUIPMENT COST (Approx.) in PKR

1. Research Components (For Experimentation) 10,000

2. Micro-Controller Unit (Development board, Programmer, etc)

5,000

3. Switches, Breakers and Meters 10,000

4. Load Panel (Resistors, Bulbs, Motor) 5,000

5. Relays and Contactors 2,500

8. Metal Casing 10,000

9. Transport 5,000

10. Miscellaneous (including printing, reference books and others)

3,000

Total 40,500

3. 1000W Inverter 5,000

4. 450W Solar Panel 30,000

Total 35,000

GRAND TOTAL 75,500

53 | P a g e

INDEXBlock Diagram................................................................................................................................................................................13Buck-Boost Converters...................................................................................................................................................................19General Idea....................................................................................................................................................................................6Goals................................................................................................................................................................................................ 7Impact.............................................................................................................................................................................................. 8Introduction..................................................................................................................................................................................... 9Inverters........................................................................................................................................................................................... 1Solar Panels................................................................................................................................................................................6, 14