500VA power inverter system is a DC to AC conversion system of 500VA power rating and expected to carry around 400 watts load. It provides power to electronic and electrical appliances such as radio sets, TV DVD/VCD, computers, fans and lighting. The design was conceived and put down as block diagram. Corresponding circuit diagrams for each black box were sourced and drawn. The component values according to desired specifications were designed from the first principle and needed values derived. The transformer was also designed and with measurements and component values we went to the market. Most of the transistors were not in the market and order was made with the trader and they were later collected. These components were first wired on project board, tested before being removed and transferred to veroboard where they were soldered permanently and tested. The tests carried out were successfully including the capacity of the transformer and the transformer stability and hum-free operation. The circuit veroboard and transformer along with meters, switches, indicators and output sucket were all carefully packaged inside the system box and test carried out again. This financial test was also successful.

TABLE OF CONTENTS

Title Page

Title Page i

Certification ii

Dedication iii

Acknowledgement iv

Abstract v

Table of Contents vi

List of tables vii

List of Figures viii

List of Appendices ix

CHAPTER ONE

Introduction 1

Background of study 1

Objective/aim of study 2

The Scope of study 3

Limitation of the study 4

Definition of important terms 5

CHAPTER TWO

Literature review 9

Feedback Oscillator Principle 10

Astable Mulivibrator Principle 11

Field Effect transistor (FET) 14

CHAPTER THREE

Design Methodology 18

Specification 19

Inverter System Circuit Design 20

Voltage Regulator Monitor 20

Inverter Circuit 22

Low Pass Filter 24

Pre-Amplifre 25

Bufer Amplifier 27

Power Amplifier 29

Transformer Design 38

Circuit Diagram 43

CHAPTER FOUR

Construction, Testing and Packing 44

CHAPTER FIVE

Bill of Engineering Measurement and Evaluation 49

CHAPTER SIX

Summary, Conclusion and Recommendation 52

Summary 52

Conclusion 53

Recommendation 54

References 55

Appendix 1: Standard were Gauge (SWG) Chart 56

Appendix II: Color Code 59

LIST OF TABLES

Table 3.1: Coefficient of Utilization 34

Table 3.2: Calculated Winding Parameters 38

Table 4.1: Transformer Test 46

Table 5.1: BEME 49

LIST OF FIGURES

Fig 2.1: Feedback Oscillator Principle 10

Fig 2.2: Astable Multivibration Circuit 11

Fig 2.3: Symbol of an Enhancement Channel (MOSFET) 15

Fig 2.4: MOSFET Power Transistor Schematic 17

Fig 2.5: Symobl of MOSFET 17

Fig 3.1: Power Inverter System Block Diagram 19

Fig 3.2: Voltage Regulator/Monitor 20

Fig 3.3: Inverter Circuit 22

Fig 3.4: Equivalent Circuit of T₂ Showing the Origin of Overshoot 23

Fig 3.5: Cascaded Low Pass Filter 24

Fig 3.6: Pre-Amplifier 25

Fig 3.7: Buffer Amplifier 27

Fig 3.8: Darlington Pair Power Amplifier 29

Fig 3.9: Output Stage 30

Fig 3.10: Transformer Schematic Diagramme 32

Fig 3.11: Transformer Turns Schematic Diagramme 34

Fig 3.12: Sketch of Transformer Core Lamination 40

CHAPTER ONE

INTRODUCTION

The Background of the Problem

Power inverter system is a unit developed for the conversion of direct current (DC) into alternating current (AC) to serve electronic and electrical appliances, such as radio sets, television sets, DVD/VCD, computer, photocopying machine etcetera and also provide lighting and power to fans. Inverter systems could be used in conjunction with the solar energy conversion system for the harnessing of solar power energy and also as vital part of uninterrupted power surprise system.

The concept and development of power inverter system because necessary of the poor national power supply system that resulted in incessant power supply and power outages. Power inverter is also found in use where there is no supply of electricity in the first place.

The Purpose/Objective/Aim of the Project

The purpose of the project is to design and construct a 500VA power inverter system for the supply of A.C power to serve load of about 400watts power (the active or real power, 500VA x 0.8 = 400 watts).

The objective of the project is to ensure that the research produce an inverter and step-up transformer that would be able to transform few D.C voltage of about 12 voltage to up to 220 volt A.C 50Hz obtainable from the national power supply. Electronic appliances designed and constructed for use in Nigeria are meant to work at the designed specification of 220/230 Volt AC, 50Hz in contrast to similar equipment meant to work in a country like Japan whose national electric power supply is 110 volt A.C., 60Hz.

The designed and constructed power inverter system in accordance with the specification of national power supply will not discriminate against any equipment nor serve only a particular electronic appliance. The inverter system will be universally accepted by any system operating in Nigeria or in countries that adopted same specification. BY this, the aim of the project design and construction must have been achieved.

Scope of the Project

This project is on the design and construction of 500VA power inverter system with an in-built battery supply. In the first place, the 12 VDC battery is not part of the system to be designed implemented. The scope of the project includes designing and deriving the component values of all the circuits involved for the implementation of this project. These components are sourced and fixed in the vero board according to the determined circuitry, wired and tested through. The circuitry is completed by the design of transformer laminations and coils or windings, packaging and clamping of these laminations to air tight condition and testing through to ensure the specified rating of 400W which will supply a real power of 500VA x 0.8.

The scope of the project also coverted testing of the entire system after packaging in a metal construction with vent that will ensure in-let of air as coolant to the transformer that is expected to generate heat while in operation including power transistors.

The power inverter system produced cannot work along wired installation of power supply from the national grid unless other units are incorporated. It works on stand alone bases where no power was extended from the national into operation intermittently.