# THE DESIGN AND CONSTRUCTION OF INVERTER

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#### THE DESIGN AND CONSTRUCTION OF INVERTER

CHAPTER ONE

1.0Â Â Â Â Â Â INTRODUCTION

1.0.1Â Â  What is an Inverter?

Direct current is a type of current that flows in only one direction. Using the conventional current flow, direct current is such that electrons leaves the power source from the positive terminal (usually marked red) andÂ  flows through the circuit and then terminates at the negative terminal (usually marked blue) ofthe power source. Direct current (DC) is usually gotten from battery cells, solar panels, household generations etc.

Fig 1.1 Graph of DC voltage against time

Alternating current is one in which current direction changes with respect to time, i.e it flows in one direction for an amount of time after which it changes direction. In this case there is no fix polarity for the terminals of the power supply. This type of current is usually gotten from, public power supply distribution companies, industrial generators etc.

Alternating current graph could take the form of sine wave, square wave, triangular wave, modified square wave etc. These graphs are shown in fig. 1.2.

Fig. 1.2 Varied forms of alternating currents (a) sine waveÂ  (b) triangular waveÂ  (c) square waveÂ  (d) modified square wave

The power supplied by industrial generator and public distribution companies is usually pure sine wave. But commercial inverters could give output ranging from square wave, modified square wave to pure sine wave. Although pure sine wave is most preferable for electrical equipments, it is usually costly because of the technology involved.The modified square wave is predominate in house hold inverters. This modified sine wave is manageable for electoral equipment compared of square wave

1.0.2BASIC WORKING PRINCIPLES OF INVERTER

The basic difference between an AC and a DC source is that, while an AC alternate its current direction or polarity, a DC has fixed current direction and polarity. The major work of an inverter therefore is to alternate the polarity of the DC power supply terminals.