1.0 Introduction
Meaning Of An Inverter
An inverter is a device that can convert electrical energy of DC form into that of Ac, the inverting process can be achieved with the help of transistors, silicon controlled rectifier (SCR), tunnel diodes etc for low and medium power outputs transistorized inverters are suitable but silicon controlled rectifier (SCR) are suitable for higher power outputs.
The working principle of an inverter can be explained with the help of a complete circuit diagram. This is a voltage driven inverter because the voltage source is connected through semi-conductor switches directly to the primary of the transformer.
S1 and S2 on the circuit diagram are switching devices (i.e. transistors or SCRs) which open and closes alternatively at regular intervals of time. The two switching devices are generally driven by an astable multivibrator operating at a given frequency. When S1 is closed, the entire dc source voltage applied across point A and B of the transformer primary winding. S1 remains closed for a certain period of time after which it is cut off and S2 closes, it also remain closed for the same period of time during which the source voltage V1 is applied across points B and C of the transformer primary S2 then opens out and S1 closes. In this way an alternating voltage is applied across the transformer primary which induces an ac voltage in the secondary.
Inverter Classification
Inverters can be classified based on factors such as input voltage, output voltage, power ratings and output waveforms. Square wave inverters are the oldest, simplest and cheapest low power devices. These inverters generally consist of an oscillator driving switching transistors that switch the incoming power to different sides of the centre tapped transformer primary.
The square wave output is quite far from the waveform available from normal mains outlet, and this can cause problems on equipments originally design with the sine wave power in mind. Most devices with variable speed such as electric drills and equipments such as cordless drills and screwdrivers behave irrationally when operating on square wave inverters.
The next step that is close to the mains sine wave is called the modified sine wave. This has become popular in many inexpensive inverters because it is quite easy to make with modern electronics. This type of inverters generally uses a switch mode power supply that generates dc voltage.
The modified sine wave is compatible with electronics but it may induce long mechanical buzzing. The true sine wave inverters allow connected load equipments to operate in the same way as they would from mains supply. The only problem is that true sine wave inverters are very expensive compared to the modified and square wave inverters.
Finally, the success of this study will be beneficial to the society at large. Mass production of inverters will lead to improved standard of living of the populace and the nation will move forward in its pursuit of technological development
1.1 Problem Statement And Need For Inverters
In the market of power inverters, there are many choices; they range from the very expensive to the less expensive with varying degrees of quality, efficiency and power output. Capability along the way. High quality combined with high efficiency exists but it is often at high cost.
There are many problems that has limited the output power and low energy an inverter can produce this include finance time access to some necessary destined component etc.
1.2 Motivation
I was motivated by the need to generate electrical power through a noiseless, portable and inexpensive source that has no negative effect on the environment. I also took up the challenge to carryout this project because of my quest to know more about power generation.
1.3 Limitation
In spite of the base of 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.
Also the use of the bulky transformer instead of copper transformer which is lighter and smaller in size but more expensive is another limitation.
Another limitation is the inability of the circuit to produce a pure sine wave output waveform. This is because it is quite expensiveness to design a pure sine wave inverter circuit.
1.4 Scope Statement
The scope of this project is to design and construction on inverter with an output power rating of 5KVA, maximum output current rating of 20.83A, output voltage of 240V from a 24dc input. Which can be used to power essential circuits such as computers, surgical equipments, security doors etc?
1.5 Objective Of Study
The purpose of this seminar is to design and construct a circuit that will take a 24Vdc input from battery and provide a 500VA (AC) output with under voltage and over voltage protection. Specifically the study intends;
- To design a circuit that converts dc power to Ac power for full households, amenities in homes.
- To design an inverter circuit with under voltage over voltage protection.
- To provide a noiseless and weightless source of electricity generation
- To have a source of generating electricity that has no negative effect on the environment (has no green house effect).
- To provide a source of electricity power with low maintenance cost and zero fuel cost
- To design and construct an inverter to be used for a full household amenities.
The study will serve as a means of impacting practical knowledge and skills to students, lecturers as well as other people who may wish to acquire themselves with the principle of operating an inverter.
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