Design And Construction Of A 2kva Power Inverter

Project and Seminar Material For Electrical Electronics Engineering EEE

Chapter One

1.0 Introduction

This project focuses on conversion of DC to AC power inverter whose aim is to efficiently convert a DC power source to high voltage AC source, similar to power that would be available at an electrical wall outlet. Inverters are used for many applications as in a situation where low voltage DC sources such as batteries solar panel or fuel cells must be converted so that devices can run on AC power. One example of such a situation is converting electrical power from a car battery to run a laptop, television, cell phones e.t.c.

The method in which the low voltage DC power is inverted is completely in two steps. The first being the conversion of low voltage DC power to a high voltage DC source, and the second step is being the conversion of the high DC source to an AC waveform using PWM (Pulse Width Modulation).

Another method to complete the desire outcome would be to first convert the low voltage DC power to AC and then use a transformer to step up the voltage to 220volts. However, due to the erratic power supply of electricity in Nigeria, an alternative means of power supply has to be incorporated to supplement the supply of electricity which one of such form of power is inverter.

1.1 Background Information and System Design

From the late 19th century to the middle of 20th century DC to AC conversion was accomplished using rotary converters, or motor generator (MG) set. In the early 20th century, vacuum tube and gas filled tube began to be used as switches in inverter circuit. The most widely use type of tube is thyraton.

The origination of electromechanical inverters explains the source of the term inverter. Early AC to DC converters used on conduction of synchronous of AC motor direct connected to a generator (DYNAMO), so that the generator commutation reversed it connection exactly the right moment to produce DC. A later improvement is the synchronous converter, in which the generator and motor winding are combined into one armature which slip rings at one end and the commutation at the other end and only one field frame.

The result is either with AC-on, DC-out. With an M.G set, the DC can be considered to be separately generated from the AC with a synchronous converter, in a certain sense, it can be considered to be mechanically rectified AC. Using the right auxiliary and control equipment, and motor generator set or rotary converter can “run backward”, converting DC to AC. Hence, an inverter is inverter converter. It should also be noted that early inverters did not use transistors for switching purposes, because its voltage and current ratings were not high enough for most inverter applications.

However, in 1975, the silicon control rectifier (SCR) was introduced as switches, hence initiating a transition to solid state inverter circuits. Today, however due to an increased knowledge in technology, modern inverters are less bulky and more efficient with the use of various components such as ICs (Integrated Circuits)

1.2 Aims and objectives

The main aim of this project is to design and construct a 2KVA inverter with 12volts supply so as to achieve the following objectives;

To ensure the protection of the back-up source consumer equipment and supply.
To back-up the erratic power supply by PHCN.
To modify sine wave that can be used to power appliances both in houses and industries.
To safely operate any electronic devices (such as micro wave, speed motor) that require sensitive calibration.

The design and construction of this project was to provide an ample chance for an understanding of the characteristics, operations, and application of power electronic devices. In addition, generally it gives an understanding of basic design concept of inverter based on MOSFET (Metallic Oxide Semiconductor Field Effect Transistor) switching and PWM (Pulse Width Modulator).

1.3 Limitation

The major limitation of this project is that it cannot operate equipment or an electronic device that is above its rated current due to some form of losses during the circuit operation.

Chapter Five

5.0 Conclusion and Recommendation

5.1 Conclusion

This project has given us better understanding of the practical aspect of our course of study (Electrical/Electronic Engineering), it has also enable us to acquire more practical skill and knowledge. The completion of this project of construction of a 2KVA inverter with 12V DC dry cell battery has given expected results after different tests were carried out on each stage which gave durable and accurate results.

The proper running of this inverter is a clear indication that the set aim and objectives have been achieved. The construction is based on the theoretical knowledge gained so far during our lecture times. It is constructed with considerable cost, available and reliable components rather than the more exorbitant unavailable ones.

The practical knowledge of the multi–purpose use of SG3524 IC, MOSFETs, relay etc makes the project interesting, tasking and educating.

5.2 Recommendations

Logically, irrespective of how good a design might be, there is always room for improvement. By so doing, the following recommendations could be taken into consideration for more effective and useful inverter.

Competent personnel should be consulted in case of any damage to the unit and every source of power supply should be disconnected from the inverter before removing the cover.
Soldering of components should take a network system in order to minimize heat to the components.
On no occasion should the inverter be loaded above 80% of its maximum capacity. It’s an international advice.
Student should be exposed to more practical works so that they would be able to construct all practical works themselves.
Government at various levels should encourage engineering practice by financing and training of engineering within and outside the country for the benefit of the students and the nation at large.