Seminar Presentation on Ups

SEMINAR PRESENTATION ON THE DESIGN AND CONSTRUCTION OF   

               5KVA POWER INVERTER WITH BATTERY

                                                    BY:

         SUNDAY E. ESHIET

         S02/EEE/2001/2807

           DEPARTMENT OF ELECTRICAL ELECTRONICS ENGINEERING TECHNOLOGY, RUFUS GIWA POLYTECHNIC, OWO.

SECTION ONE

1.0              INTRODUCTION

The importance of power supply in both developing countries is a global perspective that can not be overemphasized. However, taking Nigeria as a case study, the inconsistency of power supply has becoming a reoccurring problem, and it has been indeed a great concern for both private sector, and the government in carrying out the day to day activities. This fluctuation in power supply has affected human lives, cost of living, perishable goods and companies that depend mainly on electricity in carrying out their normal operations, hospital and even computer that has become a major household

Electronics gadget or office equipment also serve as a plus to the existence of any reliable nation as it connect one to the global world can not be use to perform its usual functions due to ON and OFF of power supply. To solve the above problems of frequency variation, surges, spikes transient radio frequency interference and fluctuation in power supply. There is the need for a system or a device that can make power relatively stable, consistence, or stand by at lower cost for short period of time and hence the use of uninterrupted power supply (UPS) finds it way in, or into the action.An Inverter unit is a device which supplies power to a systemwhen there is power failure for a period of time, depending on the battery capacity. It prevents equipment from being negatively affected when there is fluctuation in power supply, surge, low voltage, bad harmonics and so on .It protects and prevent document from being lost while working on computers. When there is power failure, it also prevent component from being adversely affected.It is an automatic device that switches without obstructing its normal operation. The inverter provides power for emergency, like in the Hospitals, NITEL, GSM station and others.

The Inverter, otherwise known as, the uninterrupted power supply, is made up of two stages, the Inverter and charger; other parts are for the circuits’ protection and for effective operation of the UPS. The Inverter converts direct current (d.c) from the battery to an alternating current, (A.C) while the charger supplements the battery whenever the power is active.

This project, the Inverter, is not design to supply power to the equipment indefinitely, but for a back uptime when there is power failure. The duration depends on the battery capacity and the equipment used. The Uninterrupted power supply (the inverter) is design in such a way as to ensure accessibility, to ease maintenance and repair.

1.1       AIM AND OBJECTIVES OF THE RESEARCH WORK

The main aim of this Research work  is to design and construct an Uninterrupted Power supply (Inverter), which has a power rating of 5000 volt ampere .The objectives to be derived from the aim are as follows:

a) To produce a UPS (inverter) with an active surge protection unit;

b) To produce a UPS (inverter) with correct power ratings and tolerance;

c) To know the basic electronics components requirement for the design and construction of the UPS (inverter);

d) To know and identify the various stages involved in the design and construction of the UPS (inverter).

e)  To produce an Inverter with no fuel requirement and virtually no maintenance.

1.2       SIGNIFICANCE OF THE RESEARCH WORK

The significance of this Research is to know the vital roles that the inverter service plays in Nigeria Economy. The study will also reveal the appropriate rating of the inverter (UPS) as a device that is suitable for particular equipment and appliances.

In addition to identify the suitability of UPS,(inerter) as a device that serves protection of office based appliances such as computers, electric fans, radios,etc.

1.3       PRINCIPLE OF OPERATION

            The inverter will be designed to works in two modes, to prevent power failure at its output. It is able to implement this function through the relay that are either converted or isolated to implement the various modes.

MODE 1: The Inverter willoperate on the power supply in mode 1 operation state. The main a.c input will be step down by the transformer to be rectified, filtered and charge the battery with 12 volt d.c supply. The block diagram is shown below.

Rectifier

Battery

Inverter

Transformer

 

    Fig. 1.3a Mode 1 operation of Inverter

MODE 2: The mode two of this mode has the inverter as the main circuit. The battery will be used to power the Inverter, and switch to prevent power failure. The transformer is switch from step up to step down transformer; the transformer will switch from step down to step up transformer to give a 220 volt output at the secondaryof the transformer.

            The back up time depends on the capacity of the battery and on the power consumption of the load, unless the main supply is restored in a good time, the inverter will step down when the battery has been discharged to prevent voltage level. The block diagram for the mode 2 operation of the Inverter is shown below.

Rectifier

Transformer

Inverter

 

                                                                                                                                                                             Output

Battery

 

         Fig.1.3 b mode 2 operation of Inverter

SECTION TWO

2. O LITERATURE REVIEW

This Section of the Literature Review of the Research work comprises the following:

Overview of the Research work,

Brief discussion of the component used, and the

Definition ofother terms.

2.1 Overview of the Research work

From the late nineteenth century through the middle of the twentieth century, generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as switches in inverter circuits- RAKESH   KUMAR (2002).

But today Inverters are designed using semiconductor switching element to complement the use of vacuum tubes and gas filled tubes as the inverter circuit.

            Several Researchers have embarked on the research work and discover new technology to improve on the old existing method old design of Inverters from the ancient times up till dates. Base on the result of research work some years ago, Inverters were designed and constructed with no correct power rating and tolerance (HND2 Electrical Electronics Project, 2010)

            Further discoveries from the research work resulted to the design of Hybrid Bridge Inverter topology. The half bridge inverter topology has lower number of switches and simple control (http://Guru/PEInverter/Half-bridg/pdf/inv.pdf,2006). The duration of dead band should be large enough to allow the switch that is turned off to close before the other switch, to start conducting. The advantage of H-bridge inverter topology has lower number of switches and simple (Emadi and Stoyan, 1992).

            More so, an inverter which is a device designed to change direct current d.c input to alternating current (A.C) output does not create or make electricity, but just changes it from one form to another. D.C in is change to A.C out (Sona Singh, 1999 and Kehua, 2007).

The knowledge got from is to produce an inverter of 5000 volt ampere (5000VA) which would be operating on automatic mode. This will supersede the type designed and constructed by a group of Researchers in ND 2 Electrical and Electronic Engineering Department, 2009.

2.2 BRIEF DISCUSSION OF THE COMPONENT USE

The following components are used in the design and construction of this 5KVA inverter;

(a)   I C SG3524N: This integrated circuit (IC) used in the design has sixteen legs or pins .Each leg has different configuration. Pin 12 and 15 are the output legs. This IC functions as an as table multivibrator, and it is used to design inverter of higher power ratings. In the manufacturer’s data sheet, this IC has low decibel power consumption of 0.32dB.

(b)   Transistors: These are three layers semiconductor devices consisting of either two N- type or P-type layers of materials. This type of transistoris known as bipolar transistor. Other types are Field Effect Transistors (FETs), and other types are Junction Field Effect Transistors (JFETs).

(c)    Diodes: They are semiconductors that are used for rectification of a.c supply to d.c supply.

(d)   Capacitors: These are passive component that stores electrical energy as charge in the electric field.

(e)   Light emitting diode: It is a diode which gives off visible light when it is forward biased. It is used for emergency indication.

(f)     Voltage Regulator: This component regulates the voltage in and out of the driver (the oscillator). It has three pins, pin 1 is the input; pin 2 is the ground (cathode) while pin 3 is the output pin .This component protect the sensitivity of the as table because of its low power consumption.

(g)   Potentiometer;these are variable resistors which are use to vary resistances in the circuits. Those ones use in this design are, 10,000 ohms and 20,000 ohms.

(h)   Resistors: These are passive components which are used to limit the flow of electric current in the circuit. The major types available for the design of this inverter are: 10kΩ, 56kΩ, 4.7kΩ, 47kΩ, 1.01kΩ, and 100kΩ and 1kΩ resistors.

(i)     The Metal-oxide semiconductor Field Effect Transistor, (MOSFETs):

 They are the power amplifier circuit of the inverter. MOSFETs having three terminals, the source, the gate and the drain are very rugged in operation and can easily damage if handled carelessly. The MOSFET chosen for use in this inverter is the IRFP150 N because of its current rating of 50 ampere and 100 volt with a power rating of 230 watts. These MOSFETs are selected depending on the maximum current and power dissipation of the project; IRFP150N MOSFETs would be used. The IRFP150N has the following specifications.

Table 2.2 shows the Characteristics of MOSFET.

ID (max)             VDS (v)               VGS (v)               PD (max)

50A                    100V                   3.0- 5.0v              230W

Where       ID = Drain current

                 VDS = Drain source voltage

                 VGS = Gate threshold voltage

                  PD =Power dissipated

Since each MOSFET has a drain current of 50A, twenty MOSFETs will be connected in parallel and is capable of 1000A which will conveniently suffice considering that on full load, 250A is adequate.

2.3 DEFINITIONS OF OTHER TERMS

a) Mono stable: Is a multivibrator that generates one shot output stage.

b) Electronic Oscillator: This is a circuit which generates a varying output signal of a particular shape and frequency.

c) As table device: They are devices that have no stable state. They switch from one state to another automatically at a rate determined by the circuit components.

d) Modality: Is the process or principle of operation of inverter. The inverter makes use of the battery as a source of energy to give out A.C signal when there is power failure, and on other hand it makes use of the supply Authority energy to charge back the battery.

e) Transformation: Is the process by which a small signal in the inductor or coil is step up to give a higher signal at the other end. This process takes place in the transformer

f) Switching control: Is the action of change from one state or

mode to another state. Control could be either manual or automatic.

Manual control requires the help of individual to operate while automatic control operate without the operator`s intervention.

g) Zener Diodes: The function of this circuit is to indicate through the glowing of the led assigned for fault indicator when any input to the inverter circuit whether the mains of battery supply is low for the inverter operation. It is use of the indication when there is any abnormality in the inverters operation. The Zener diode (18v)is use as a reference element.

h)Transistor C9014: This transistor will be used in this circuit to amplify the output from the oscillator. Its characteristics are:

Collector – Base voltage (VCBO) =50v

Collector – Emitter voltage (VCEO) =45V

Emitter –      Base voltage (VEBO) =5V

Collector current (IC) =100mA

Collector Dissipation (Pc) =450mW.

i) Voltage Regulator: This component regulates the voltage in and out of the driver (the oscillator). It has three pins, pin 1 is the input; pin 2 is the ground (cathode) while pin 3 is the output pin .This component protects the sensitivity of the as table because of its low power consumption.

SECTION THREE

3.0 THE RESEARCH METHODOLOGY

This section talks about the Research Methodology which entails, the block diagram and explanation of the inverter, and the circuit diagram and explanation.

3.1 THE BLOCK DIAGRAM

Rectifier

Multi-vibrator

FET

 

A.C Input                                                                                                                     Output

Battery

 

                                                                                                           

The heart of the UPS is the Inverter, which is made up of the oscillator and FETs. It converts the d.c voltage into an A.C output and supplies it with power for higher current holding capacity. It has high switching speed compared to its electronic components. The rectifier is supplied by the electric utility network with a.c power. In the event of future of main power supply the inverter will be supplying directly from the battery. The inverter is normally protected against overload, short-circuit and overheating. This arrangement is very practical and economical for providing power lighting, communication equipment, computers etc. This various equipment is composed of numerous electronic components such as resistors, capacitors, inductors, transistors, thyristors and relay, the UPS is a modular form. Each module consists of each stage such as the battery charger, regulated power supply, inverter, rectifier, etc.

3.2.1 CIRCUIT DIAGRAM

CIRCUIT DIAGRAM EXPLANATION

This is a voltage driven inverter because the dc voltage source is connected through semiconductor switches directly to the primary of the transformer.S1 and S2 are switching devices (i.e transistors or SCRs) which open and close 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 remarks 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 v, 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 reduces an ac voltage in the secondary

SECTION 4

4.0 CONTRIBUTION TO KNOWLEDGE

In the course of the Research work on the design and construction of 5KVA inverter, we were able to know the different applications of a component to various designs of circuits.

Also, this research work has exposed the immense contribution of electronic in Technological development. I am very sure that more development can still be achieved that could contribute to the standard and accuracy of the Inverter since new request kept on coming up virtually all the time.

SECTION FIVE

This Section comprises the summary, conclusion and the recommendation.

5.1 Summary

The construction and design of 5000 Voltage ampere Inverter (5KVA) which converts a D.C voltage source, (battery) by the oscillator circuit to an alternating current A.C The signal from the conversion is amplified by the amplifier circuit and fed into the transformer for transformation. The protective device used in this Inverter is fuse with its fusing current of 13A and 15A. Relays are used to perform the change-over operations function. The output frequency is 50Hz with the output voltage of 220 /240volt A.C.

5.2 CONCLUSION

        The project which is the design and construction of a 5Kva inverter was carried out, and inputs were based on the following factors: economy, availability the components and research materials, efficiency, compatibility, portability and durability. The performance of the project after test met design specifications. The general operation of the project and performance is dependent on the user who is prone to human error such as overloading the system, making wrong battery connection or using the wrong battery voltage.

         Also the operation is dependent on how well the soldering is done, and the position of the components on the clay board (if ICs are soldered near components that radiate heat, overheating might occur and affect the performance of the entire system).

         The construction was done in such a way that it makes maintenance and repairs an easy task and affordable for the user, should there be any system breakdown.

         The project has really exposed me to power electronics and practical electronics generally, which is one of the major challenges I shall meet in my field now and in future. The design of the 5KVA inverter involves research in power electronics. Intensive work was done on the oscillator circuit, under voltage and overvoltage circuit, switching circuit and the transformer.

 The project is quite challenging and tedious eventually was a success

5.3 RECOMMENDATIONS.

         After the completion of this project work, the following recommendations are necessary so as to achieve a high output and efficient inverter:

*Further research should be done on the area of other energy sources like solar and windmill.

*A more simplified schematic diagram should be adopted in order to reduce interconnection, thereby easing troubleshooting.

*Research should also be done on building very large capacities of inverters like 10KVA and above with longer length of time of operation at full rated load.