Abstract

This work is on the design and construction of a 5KVA Pulse Width Modulated (PWM), Metal Oxide Semiconductor Field Effect Transistor (MOSFET) based Inverter, which works on the principle of Pulse Width Modulation. The inverter uses the IC SG3524 and a pair of Twelve MOSFETs to drive the load. The design and implementation starts with the power supply. Component selection was made with the aid of electronics data book, which made the design and calculations very easy. One main feature of this inverter is the monitoring section, and the battery-charging section connected to the inverter circuit. The inverter converts DC supply of the battery into AC power supply required by most electrical appliances/equipment when the AC main is not available, and when the AC main is available; this AC mains supply goes to the AC mains Sensor, the Relays and Battery charging section of the inverter. This inverter can be used for domestic purpose and it is not recommended for industrial purpose where high current is required for application, such as starting a heavy-duty motor.

Chapter one

Introduction

1.1 Background to study

The erratic nature of power supply is a thing of major concern to all Nigerians. The cost of acquiring a generator set and the need to supplement the irregular voltage supply by the Electricity Distribution Companies of Nigeria make it essential for the construction of the DC/AC power inverter.

An Inverter is a device, which converts the DC supply of the battery into AC power supply required by most of the electrical/electronic equipment [9]. The process through which the

Inverter converts DC power supply to AC power supply is called INVERSION. This inversion process is the reverse of the rectifier process, where the AC is converted into DC power supply.

In the past, Pulse Width Modulation (PWM) techniques were employed in voltage and current source Inverter only. Availability of self commuted devices, such as power transistor, Metal Oxide Semiconductor Field Effect Transistor (MOSFET), Insulated Gate Bipolar Transistor (IGBT) and Gate Turn-off Thyristor (GTO), have made pulse width modulated AC to DC converter also popular in many applications. The steady state and dynamic performance of Inverters, AC to DC converters, and DC and AC drives are significantly dependent on the pulse width modulation techniques [1].

Pulse Width Modulation (PWM) of a signal or power source involves the modulation of its duty cycle, to either convey information over a communication channel or control the amount of power sent to load [4].

Generally, in every home, office and industry, electrical/electronic devices are installed for use. These devices require electrical power for their operation; and most of these devices when not supplied with the required quality power supply, are at risk of being damaged.

In Nigeria, the standard electrical/electronic equipment work on 220V/50HZ AC power supply. This power supply should not contain spikes, noise etc which could lead to damage of the equipment.

With this direct current (DC) to alternating current (AC) power Inverter, people now have an alternative to power supply when there is an outage thereby reducing irregularities in power supply by the National Power body – Electricity Distribution Company of Nigeria.

This device (Inverter) will be of immense importance to rural dwellers and serve as a substitute to power supply and big generating plants. In terms of cost, size and reliability, the device stands the test of time and is relatively portable and cheap compared to other means of power generation.

Primarily, the inverter converts DC power to AC power at a desirable output voltage, current and frequency. The conversion may be achieved with such devices like the ICs, MOSFETs, capacitors, resistors, diodes, and bipolar or unipolar transistors when properly arranged and combined [2].

Based on this definition and the availability of AC power, the importance of an inverter and the need for a constant source of AC power in Africa and many other developing nations cannot be over emphasized. In most of these countries, AC power is very erratic. In Nigeria, for example, there is always an incessant supply of electricity.

The DC voltage can be obtained from solar power and DC batteries. Thus, on the basis of inversion, this work shall reveal how DC power to AC power (that is converted) may be used to power fluorescent tube, television set, radio, printer, Computer and also for general purpose.

1.2 statement of problem

Every home, office and industry, electrical/electronic devices are installed for use. These devices require electrical power for their operation; and most of these devices when not supplied with the required quality power supply, are at risk of being damaged.

In Nigeria, the standard electrical/electronic equipment work on 220V/50HZ AC power supply. This power supply should not contain spikes, noise etc which could lead to damage of the equipment.

With this direct current (DC) to alternating current (AC) power Inverter, people now have an alternative to power supply when there is an outage thereby reducing irregularities in power supply by the National Power body – Electricity Distribution Company of Nigeria

Hence, this research seeks to develop a reliable 5kva inventer that will less the overdependent of electrical companies while providing a solution to issues of power outage.

1.3 Aims and objective

The primary aim of this study is to proffer a solution to issues of power supply and power outage by providing step by step analysis of production of a 5kva power inverter.

1.4 Significance of study

This study is significant in a whole number of ways, not just to proffer solutions to the issues of power outage but it will also provide as a source of information to new researchers who would love to further investigate deep into the topic. It is a great means to share this knowledge of electrical production to the public.