DESIGN AND CONSTRUCTION OF 5KVA INVERTER
This inverter is designed to convert ac power from higher capacity dc batteries to A.C voltage (power) for systems that use ac only. It uses 24v battery D.C times 2, which is converted by the MOSFET to A.C. it is used I.C. with the model number SG3525 where the four MOSFET is connected to it. It consists winding which enable to determine the number of wattage. The inverter consist of four section (i) supply unity (i) Triggering or Switching unit (ii) Buffer stage (iv) step-up transformer unit.
TABLES OF CONTENT
Title page i
Approval page ii
Tables of contents vi
1.0 Background of the study 1
1.1 Objectives of the project 4
1.2 Scope of the project 5
1.3 Organzation of the project 6
2.0 Literature review 9
2.1 Description of components 13
2.2 Transformer fundamentals 14
2.3 Capacitors 17
2.4 Resistors 18
2.5 Transistors 19
2.5.1 Bipolar junction transistor 20
3.0 power inverter block diagram 24
3.2 System operation with block diagram unit description 25
3.3 Battery, Power supply unit 25
3.4 Battery capacity. 26
3.5 Oscillator driver stage and buffer unit 27
3.6 Buffer stage 28
3.7 Transformer stage 28
3.8 Change over stage 29
3.9 Feedback 30
3.10 complete circuit diagram of inverter 31
3.11 Principles of operation 33
4.0 Design and construction procedure 35
4.1 Features of the device 35
4.2 Construction of the rectification circuit 35
4.3 Oscillator circuit 36
4.4 Buffer circuit 39
5.0 Circuit construction, testing and packaging 43
5.1 Component sourcing 43
5.2 Prototype construction 44
5.3 Actual constructions 45
5.4 Testing of the inverter system 47
5.5 Packaging 48
5.6 Trouble shooting 51
6.0 Conclusion and recommendation 54
6.1 Conclusions 54
6.2 Recommendations 55
LIST OF TABLES
Table .2.1 various values of capacitors 18
Table 2.2 Values of Resistor 19
Table 2.3 Transistor values 20
Table 5.1 Bill of Engineering Measurement and
Evaluation (BEME) AS OF December 2013 52
LIST OF FIGURES
Fig. 2.1 Laminated core type of transformer 17
Fig.2.4 Field effect transistor (FET) 19
Fig.3.1 Blocks diagram of 5kva inverter 24
Fig. 3.4: Circuit diagram of 5kva power inverter 31
Fig. 4.1 Full wave rectification circuit 36
Fig. 4.2 Inverting stage 37
Fig. 4.3 Puls width switching 37
Fig. 5.2 Strip type of vero board 46
Fig .5.3 Casing (a) Top (b) Side (c) Front of the casing 50
1.0 BACKGROUND OF THE STUDY
It is a well known fact today that electrical power supply is not reliable. All over the world, there is a significant electrical power supply interruption. Because of these electrical power supply interruption, many electrical equipments have either developed problems or even stopped working entirely. Hence this has crippled much business thereby affecting even the economy of many countries as Nigeria. Also there is increase in occurrence of power supply disturbance, which can be viewed as a form of power pollution. High voltage spikes and momentary voltage drops are therefore common. These power disturbance may affect the performance of sensitive equipment in private and corporate organization causing loss of data ad even damage to equipment.
In Nigeria today, it is not an over-statement to talk about the epileptic supply of electrical power. This has become the order of the day such that many Nigeria now view these power outages as “Normal” and part of their daily life. A wide range of factors have been identified for this problem. They include natural disasters, vandalism, maintainability and sustainability and lack of local content. The problem of poor quality power supply cannot be properly addressed without a review of other factors such as lack of political will to invest adequately in power sector, absence of replacement policy resulting in obsolete equipment, unsustainable human capacity building and inadequate reward and remuneration system to motivate human resources team to perform well.
According to the recommendation made by the Institute of Electrical Electronics Engineering (IEEE), the supplies that should be available for use should be continuous, uninterrupted with constant frequency and within the load determine in terms of voltage and current. These requirements have become even more relevant in view of the high sensitivity and sophistication of modern technological equipment in use today.
The progress made in developing alternate source of energy over the last decades has shown that independent power systems are not only possible but also very practical. In fact a wide variety of generating equipment is now available to allow individuals take advantage of just any renewable source of energy, for number of reasons, however, most of these system produce only direct current (DC) and often do so only at low voltages. Nonetheless, it is generally agreed that the greatest and most useful form of current is the Alternating current (AC), since these exist in the vast majority of homes.
Therefore, there arises the need to able to convert Direct Current (DC) to Alternating Current (AC) that will be of a constant frequency and also be used to power electrical circuits either in homes or in industries. Such electrical device is called an INVERTER.
An inverter is a power electronics device or apparatus which converts direct current to alternating current, allowing the direct current power from these generators to be used with ordinary a.c appliances and or mixed with the existing electrical grid.
An inverter is an electrical device that converts direct current (DC) to alternating current (A.C); the converted A.C can at any required voltage and frequencies, with the use of appropriate transformer, switching and control circuit. Inverters are commonly used to supply A.C power from D.C sources such as panels or batteries.
This inverter is designed to provide uninterrupted 220volts a.c supply to the loads connected at its outputs socket. It provide a constant a.c supply to the output socket even when the a.c mains supply is no longer available. When the a.c main supply is available, it goes to the a.c mains sensor, relay and battery charging section of the inverter. This a.c mains sensor informs the relay about the availability of a.c mains supply. When this relay receives a.c mains signals from the main supply, it directly passes the a.c main signals to the inverter output socket.
The electrical inverter e.g. 5000watts or 5KVA, 220-240v, 50Hz, is high power electronic oscillator. It is also named because early mechanical AC to D.C converters were made to work made to work in reverse and thus were “inverted” to convert D.C to A.C. the inverter performs the opposite function of a rectifier.
If one want to select an inverter, like 5000watts,
Total load to be connected = 5000watts
Power factor = 0.8(all inverters have a power factor between 0.6 and 0.8)
Inverter VA = 5000/0.8 = 6250 VA
So select a 7000VA inverter to run 5000watts loads
1.1 OBJECTIVES OF THE PROJECT
In this project, a 5KVA D.C to A.C inverter will be constructed and analyzed. The primary objectives or undertaking this project is for the following reasons:
1. To provide an uninterruptible alternative power supply that will be able to power the street light in the department of electrical and electronics engineering building block.
2. To design an electrical system capable of producing power from a 12v D.C battery that will produce an output of 5000watts, 50Hz–240v which Will be used to drive electrical appliances.
3. To improve our understanding on simple electrical designs, building of electrical circuits and basic principle of operation of inverter.
4. To actualize in practice the principle of circuit design and analysis.
1.2 SCOPE OF THE PROJECT
This project covers the design and construction of 5KVA, 220-240volts inverter with the following stages.
i. Power Supply unit.
ii. Inverting unit
iii. Power transformer unit
iv. Triggering unit.
The scope of this project is primarily to show how the low voltage D.C power supplied is used to energize the circuit. It will also show how the inverter units convert the low voltage D.C into a low voltage A.C in form of square wave. The triggering unit provides the trigging pulse needed by MOSFET to operate.
In general, an inverter system has many benefits and features such as:
1. Noiseless, Fuel and Maintenance free.
2. High charging current for quick recharging up to 5 times faster.
3. Bypass mode allows for charge only.
4. Generator compatible allows longer runtime.
5. Unlimited battery expansion capability to increase runtime.
6. UPS Function for auto changeover.
7. automatic voltage regulator
8. Brownout and over voltage protector
9. Small and light in dimension
10. Reverse polarity warning
1.3 ORGANZATION OF THE PROJECT
The 5KVA, 220-240v, 50Hz inverter is constructed using the following components:
Integrated circuits (ICs)
The MOFSET is the major component used in the inversion of Direct Current (D.C) to Alternating Current (A.C).
This 5KVA inverter project report is arranged in the following sequence:
- Chapter one discuses a general introduction to the project. It gives us a background of the project. Helping us to see the relevance of this inverter project in the world today. It also discusses the objectives of an inverter as well as its type
- Chapter two discusses the various literary review opinions and ideas that various authorities in the world of electronics, discusses about the inverter system.
- Chapter three discuses a general description or the various components used in the construction of this project.
- Chapter four discuses the construction procedure.
- Chapter five shows how the project was packaged and its conclusion.
In this chapter, an inverter has been described and introduced. The relevance of an inverter system as well as its objectives was also shown in this chapter one.