Design And Construction Of 2kva Inverter

CHAPTER TWO
LITERATURE REVIEW
2.0  INVERTER
    An enabling technology, power electronics does it job with intelligence, precision and efficiency. It used the smartness of advanced control technology with the efficient conversion of electric power into the precise from required to control a function or process. In a industrial and commercial products, it is gaining ground mostly visible among inverters which converts direct current (DC) into a single or poly phase AC voltage at a desire aptitude and frequency whose power rating now runs from 1000W, 20MW and more.
The operation of certain devices such as sensitive electronic equipment used for data processing, communications and control functions requires continuous and disturbance free AC power. inversion is the process by which an AC voltage or current or both is being produced from DC source and AC source. Both processors are affected in a similar way i.e by means of periodic communication, or switching of the supply to be transferred in such a manner that the desired type of output result.        
    The generation of electric power involves various sources power evolving from some primary energy sources such as:
i.    Conversion of electromagnetic radiation in a photo voltage cell
ii.    A rotating generator
iii.    Conversion of chemical energy in a fuel, cell or a battery
iv.    Conversion of kinetic energy by the magnetic hydro dynamic process.
2.1 HISTORY OF INVERTER
    The quest to convert DC power to AC power has been since the late 19th century and from them to the mid-20th century, DC to AC power conversion was accomplished by using rotary converters or motor generator sets (Ma Sets). In the early 20th century, vacuum tubes and gas filled tube was used as switches in inverter circuits. The origin of electromagnetic converts explains the source of term inverters.
    Early AC to DC converters used on inductor or synchronous AC motor directly connected to a generator (dynamo) so that the commutator of a generators reversed its connection at exactly the right moment to produce a DC source. It later development a synchronous converters in which the motor and generator winding are combined into one armature with a slip rings at one end and a commutator at the other with only one field frame. This result is a DC in and AC out. So, with Ma-sets, the DC can be considered to be separated generated from the AC with synchronous convert.
In a certain case, it can consider to be “mechanically rectified AC”. Given the right auxiliary equipment, an rotary converter can be running backward, converting DC to AC. Hence an inverter can be referred to as a DC-AC CONVERTER.
    In modern inverter circuits, the DC power source is connected to a primary of transformer through the center tap of the primary winding. A switch is rapidly switched it back and forth to allow current to flow following two alternate paths through one ends of the primary winding and the other. The alternation of the direction of flow current is the primary winding of the transformer produce an alternating current in the secondary winding. The electromechanical version of switching device includes two secondary contacts and spring supported moving contact. The spring holds the movable contact against one of the stationary contacts and the electromagnet pull the movable contacts to the opposite stationary contact. The current in the electromagnet is interrupted by the action of the switch, so that the switch continually switches rapidly back and forth. This is electromagnetic inverter switch called vibrator or buzzer was used in vacuum automobile radio. The latest inverter circuits have transistors, FETS, SCR, and other electronics switches incorporated in them because of their advantages over electromagnetic switches.
    Recently, medium power inverters have undergo significant changes. The 2KVA-2MVA inverters serve in variable speed motor devices, uninterrupted power supply, power line conditioners and active filters. One improvement stems from new power transistor such as insulated gate bi-polar transistors with their increasing voltage and current carrying compatibilities and increasing switching frequencies. Others derives from the use of digital signal processors and such modern control techniques as fuzzy logic and neutral network as well as advances in the application of power converter that employs soft switching of the power  device IEE (1986). (http://www.falana.tripid.com/tope/index.blog?entry id=195483copy)