1.0 Introduction
1.1 Background of the Project
From the late nineteenth century through the middle of the twentieth century, DC-to AC power conversion was accomplished using rotary converters or motor- generator sets (M-G sets). in the early twentieth century, vacuum tubes began to be used as switches in inverter circuits. The most widely used types of tube were the thyretron.
The origin of electromechancal inverters explains the source of the term inverter. Early AC- to DC converters used an induction or synchronous AC motor direct-Connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC. A later development is the synchronous converter, in which the generator and motor windings are combined into one armature, with slip rings at one end and a commutator at the other end only one field frame. The result with either is AC-in, DC- out with an M-G sets, the DC can be considered to be separately generated from the AC, with a synchronous converter, in a certain sense can be considered to be “mechanically rectified AC”. Given the right auxiliary and control equipment, an M-G sets or rotary converter can be “run back-wards”, converting DC to AC. Hence an inverter is an inverted converter.
1.2 Objectives of the Project
The main objective of this project is to have a device which ensures that there is an alternative source in case of any form of power failure from utility power supply. An inverter as earlier said, is an electrical or electro- mechanical device that convert direct current (DC) to alternating current (AC): the resulting AC can be at any required voltage and frequency with the use of appropriate transformers, switching and control circuits.
1.3 Uses and Application of the Project
Inverters find several applications, some of them are in variable speed AC motor drives, uninterruptible power supply (UPS), mobile AC power supplies (operating on a battery), induction heating etc.
An inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage, in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage.
1.4 Definition of terms
An inverter is a device that changes DC power into AC power. The inversion process can be achieved with the help of transistors, SCR and tunnel divides etc. for low and medium outputs, transistorized inverters are suitable but for high power outputs SCR inverters are essential. For very low voltage and high current requirement, tunnel diode inverters are used.
Inverters can be classified broadly as:
- Voltage source inverter (VSI) and
- Current source inverter (CSI)
In VSI, input to the inverter is a constant DC voltage. This is usually obtained by connecting large capacitors at the input.
In CSI, the input to the inverter is a constant current source, which is usually obtained by using a large inductor in series with the voltage source at the input.
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