Design and Construction of an Inverter
Chapter One
Preamble of the Study
Another main area where this equipment can be of great utility is in communication system. In a situation where there is a constant AC power supply failure example in offices DC – AC inverter is needed and such cases, inverter can be used as a source of light.
Most industries in the country do not make use of DC – AC inverter because there are through to be costly with respect to the task they perform. However, putting into consideration the task, this appliance can perform. It can be concluded that it is cheaper. The construction is simple, cheaper, easy to operate and portable. The usefulness of this device and the function cannot be over emphasized especially now that our country is passing through a very sensitive era in our power generating Authority (NEPA) has been dubbed NEVER EXPECT POWER ALWAYS. In these times when control and monitor of complex field operations have based in computer, a failure of AC, power supply to communication equipment means work stoppage and to some small scale industries a lot of economic and materials losses is avoidable.
CHAPTER TWO
TRANSFORMER FUNDAMENTALS
A transformer is a piece of apparatus which it’s operation is by electromagnetic induction. This also comprises of two circuits which a change in current in one circuit leads to a voltage induction in another circuit by a phenomenon known as mutual induction.
The circuit of a transformer is made up of primary and secondary circuit. Each circuit comprises of coils, E and I lamination and also former. The coil is wound on the former to assist the coupling between them and this improve their mutual inductance power from the AC mains supply to one coil or sets of coils, the voltage across these coils being either higher (stepup) or lower (stepdown) than the voltage supplied. The coils of which power is fed known as the primary and those from which power is taken is known as the secondary.
The coil has a different sizes of wire guage. The size of each winding bears a definite relationship to the power supplied or drawn from it. The number of turns is controlling the voltage and the resistance is expressed as the diameter of the wire controlling the current. The E and I lamination of a transformer is build-up of thin sheets of iron and this is a method used in all practical transformer. Clearly the core as well as in the induced current in the core were one mass of metal with very low resistance, the current so induced would be succedingly high. It is necessary therefore to increase the electrical resistance of the core which can only be done as described by splitting it into thin sheets and in-thereby causing eddy current to flow but the total loss of power so caused will be for less than it would otherwise have been.
Lamination are insulated in several ways by chemical treatment of the metal surface, by vanish or by very thin cemented paper. When laminations are being inserted into the finished coils on their former, they must be alternated i.e. E must go in from left and I from right and E from right and I from left and so on. The lamination being brought into light contact with no air gap.
There are different applications of transformers, such as impedance matching, coupling isolation, stepping down voltages or stepping up voltages.
In this project step-up transformer is used. This transformer core which are E and I type are usually made up of electromagnetic materials of high permeability.
The E – I type core used in this project has the advantages of working well at high frequencies more efficient in terms of energy conversion and has also the advantage of less magnetic flux leakage, better coupling and are better adopted to lower voltage transformer.
The circuit diagram of a single phase winding on a shell type construction is shown core is twice each of the outer limbs and the flux through it is also proportional.
The rating of the core depends mainly an the maximum current it can safety carry, so during designing of the transformer, the size and the type of core, must be considered. The core is built up than the lamination and these are brought in from of stamping form reliable manufacturer of the core flux which is proportional to voltage.
The transformer ohmic or copper losses depends an the winding current as the total losses determines the maximum transformer temperature, it’s rating must include information of the voltage and current, the product of the current and voltage would evidently be a meaningful rating measure. This is why transformer are rated on their VA, KVA & NVVA. The general fomular connecting the number of turns of winding in a given voltage, cross-sectional area of the core, operating frequency and flux density is given as:
CHAPTER THREE
DESCRIPTION OF COMPONENTS
The components used in constructing the circuit of oscillator stage and buffer stage are listed below. This includes resistors, capacitors, Bipolar junction transistors known as (BJT) and Unipola transistor known as (FET), and Zener diode.
RESISTOR
Resistors are used in circuit to limit the flow of electric current in specific areas. Therefore, they control the circuit current and keep different parts of the circuits at their required values. They are easily recognized by their coloured bands. Although there are exceptions most small fixed value resistors have four or five colour bands indicating their value. Some of the resistors are made of carbon and others of wire. The amount of resistance is measured in ohms, they are usually manufactured in the required ohmic value. They are rated in a kilowatt which determines its ability to absorbs heat.
Among the resistors that can also be used in other circuits are variable resistors while the previous one discoursed above is fixed resistor. The values of the variable resistor is not constant and hence the name variable resistor. The values are written on the body.
Physical appearance of fixed resistor.
CHAPTER FOUR
OPERATION AND DESIGN CONSIDERATION
FEATURES OF THE DEVICE
The DC supply unit along with other units of the device are shown in the block diagram below.
CHAPTER FIVE
CONSTRUCTION PROCEDURE AND TESTING
In building this project the following procedure took place.
(i) Buying and purchasing of the needed materials.
- making out a schematic diagram of how to arrange the materials or components.
- Testing out to see if the design works.
- Implementation of design of the project.
After having produced all the materials and proceeded into the arrangement of the components into vero-board. Soldering followed. The components were all soldered into the board after which, it was correct.
CHAPTER SIX
ASSEMBLING OF SECTIONS
Having provided the casing and having finished the construction of all the sections of this system, their arrangement or assembling into casing followed. The sections were properly laid out and assembled into the casing where the general coupling and linkages into all the peripheral devices took place.
TESTING OF SYSTEM OPERATION
In this stage, the system was due for testing and operation. The system operation was tested were all its required performances was maintained. It was run with battery which was connected properly to the circuit.
Suddenly, inverter started working thereby given out light as if it is NEPA. Meter in the casing is used to indicate the output voltage whether it is high or low. When the battery is getting weak the meter which is reading the output voltage will as well start decreasing gradually until the battery stops working thereby telling you to charge your battery for it to work efficiently.
CHAPTER SEVEN
INSTALLATION OF COMPLETED DESIGN
This project is suitably used by computers and other loads higher power factor for efficient production.
It has two wire outlet-positive negative wire respectively.
Here will explain just a basic set up. So you batteries is charged and you want to connect your inverter, so lets make sure the inverter has the correct input voltage, for a car or track 12voltes or 24votls… for a wind turbine you will be probably using batteries in series so your output voltage will be in steps of either 12volt 24/36/48volts. Ok, so it has the right voltage look now at the back of the inverter it should have two large screw on lugs or terminals one black / negative and one red/ positive. So the positive goes to positive (Really Important) on the battery and negative to negative. Before you start, make sure that unit is switched off. Sometimes when you connect these
terminals it can make a spark, do not worry its sometimes normal. It would also be a good idea to put a large cut of switch between the battery and the inverter, these are available at most car track stores. Then on the front you have your socket. Make sure the output voltage is set to the country or the appliances you are using. Plug it into the socket one the front of the unit. Make sure the appliance is switched off. Power up the inverter (always do this first) then switch on your appliance. That’s it.
CHAPTER EIGHT
CONCLUSION
This project has exposed us to a lot of knowledge in the field of electronics and other related fields. The task of designing and constructing an inverter has not been an easy one but thanks to the Almighty GOD and also the ESUT community for given us the opportunity to embark on this project. The knowledge we obtained from this project will go a long way in helping us wherever we may find ourselves in future.
I recommended this project report to all and sundry who may wish to research on this field. Therefore, the use of this project will help to reduce research cost.
REFERENCES
- Dr. Eke (2007), Fundamentals of Solid state Electronics, Adit Press Ltd 1A Presidential Road, Onu-Asata, Enugu
- N. Onoh (2006); Digital Electronics, Second Edition, Innovation Onyiume Str. Ogui New Layout, Enugu
- Eneh (2003), Modern Control Systems NEngineering, Rojoint communication services Ltd, Adelibu Street, Uwani, Enugu
- Africa Power Inverters: cotek, Power master sole distribution and services centre www. Sinetech.co.za
