Electrical & Electronics Engineering

Design and Construction of 1.5 KVA Inverter

ABSTRACT

This project reviews the conformability of an uninterrupted power supply through the use of an inverter. An inverter is a system that converts a direct current to an alternating current.  However, the inverter is of different categories based on power rating such as 1KVA, 1.5KVA,1.5KVA, 5KVA, etc. Moreover, since the invention of inverters, some problems associated with alternative power supply had been drastically reduced. Meanwhile, the problems such as noise, production of fumes, cost of procurement of oil, fuel, and maintenance of the plant are over.

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE STUDY

The quest to convert D.C. power to A.C power to run some essential appliances results due to erratic power supply being experienced. Although, between the 19th century to mid 20th century, D.C. to AC power conversion was accomplished using rotary converters or motor-generator sets (M-G set). In the early 20th century, vacuum tubes and gas-filled tubes began to be used as switches in the inverter circuit. In contrast, the early A.C. to D.C. converters used an induction or synchronous a.c motor directly connected to a generator (dynamo) so that the generator’s commutator reverses its connections at exactly the right moments to produce D.C.

Considering the above reasons, for the study, many electrical types of equipment have either developed a problem or even stopped working entirely. As a result, many businesses have been crippled thereby affecting the economy as a whole concerning Nigeria.

Again, power disturbances occurrence is on increase resulting in high voltage spikes and momentary voltage drops, this often affects the performance of sensitive electrical electronics equipment.

An incessant supply of electric power can not be over-emphasized in Nigeria presently, this has become the order of the day and many Nigerians now presume power outages as a normal routine in the power sector. There are factors responsible for this ugly situation such as natural disasters, vandalism, maintainability, sustainability, inadequacy, and lack of vision by the political leaders to invest adequately in the power sector, also absence of replacement policy resulting in the absolute abandon of electrical equipment or project, unsustainable human capacity and inadequate and remuneration system to motivate human resources term to perform well on their course.

The progress made some decades ago in developing alternate sources of energy has proved that independent power systems are not only possible but as well practical. A wide variety of generating equipment is now available to allow individuals to take advantage of any preferred renewable resources of energy. Most of these systems produce only direct current (DC) for several reasons and at low voltages. However, it is well known that the alternating current is the greatest and most useful form of current being generated by the power grid due to its advantages over direct current. Thus, most of the appliances and equipment are built using a.c. input source.

Therefore, there arises the need for converting direct current (DC) to an alternating current (A.C.) having a constant frequency. This process is known as inverting.

1.2 OBJECTIVE OF THE PROJECT

The purpose of this project is to design and construct a circuit that will take a 24V dc input from the battery and produce a 200VA (AC) output at 200V – 220V, 50Hz with under-voltage and over-voltage protection. The study intends:

i) To design an electrical system that converts d.c. power to a.c. power to drive various appliances used in the laboratories, theatres, rural areas, etc.

ii) To have a source of generating electricity that has no negative effect on the environment (i.e. no greenhouse effect).

iii) To provide an exposition to the HND students to simple electrical design, analysis, and building of circuits.

iv) To provide a noiseless and weightless source of electricity generation.

v) The study will also serve as a means of imparting practical knowledge and skills to students, lecturers, and others who may wish to acquaint themselves with the principles of operation of an inverter system.

1.3 THE SCOPE OF STUDY

The scope of this study is to design and construct an inverter system with an output power rating of 1.5KVA, maximum output current rating of 9.09A, and output voltage of 200V a.c. at 50Hz from a 24V dc input. A few most widely used applications of inverter include running of computers, microwaves, and electrical power tools, etc.

The scope of this project shows how a low voltage d.c power supply is used to energize an inverter circuit. It also shows how low a.c. the voltage obtained from the oscillator output is being amplified and stepped up to a required output voltage.

1.4 LIMITATION OF THE STUDY

Despite the construction of an inverter and its noiseless and pollution-free nature unlike other alternative sources of generating electricity, there is a need for charging and recharging the battery from time to time.

The inability of the circuit to provide a pure sine wave output gives room for further improvement. This is because it is quite expensive to design a pure wave inverter circuit.

Again, lack of financial assistance incapacitated the project to achieve its accuracy and reliability as well as its appearance (packaging).

1.5 DEFINITION OF IMPORTANT TERMS

Since the inverter system is an electrical/electronics system, current will flow through the various components, the voltage will be dropped at some points, and therefore, the following principles were applied in designing the project.

1.5.1 Joule’s Law

Joule has two laws Viz:

Joule’s first law shows the relationship between heat produced by an electric current flowing through a conductor. That is the rate of heat generated (p) in a metallic conductor is directly proportional to the square of the current (I) flowing through the conductor provided that temperature is held constant

Q  α I2_____ (1)

Q  = I2R _____ (2)

Q = I2Rt _____ (3)

Where Q is the amount of heat in joule, I is the electric current flowing through a conductor in ampere, R is the amount of electric resistance present in the conductor in ohm and t is the amount of time it occurs in second.

Joule’s second law: States that the internal energy of a gas does not change if volume and pressure change but does change if temperature changes.

1.5.2 Ampere’s Law: This relates the integrated magnetic field around a closed loop to the electric current passing through the loop. Thus for any closed loop path, the sum of the length element times the magnetic field in the direction of the length element is equal to the permeability times the electric current enclosed in the loop.

1.5.3 Faraday’s Law of electromagnetic induction: It states that whenever there is a change in magnetic flux linked with a circuit, an emf is always induced in it and the magnitude of the induced emf is equal to the rate of change of flux linkage.

e.m.f generated =

1.5.4 Lenz Law

When an emf is generated by a change in magnetic flux according to Faraday’s law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it.



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