THE DESIGN AND CONSTRUCTION OF INVERTER
An inverter is an electronic device that converts direct current (DC) to alternating current (AC) the converted Ac can be at any required voltage and frequency with the use of appropriate transformers, switching and control circuits. It’s simply put, is an electronic box that makes household electricity for everyday items. It converts power from eg car batteries, windmills, solar panels, or fuel cells, then turns it into normal household power. That is supply AC power from a DC source. Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high voltage direct current applications that transport bulk power. The Inverter performs the opposite function at a rectifier. There is one more thing you need to be very careful about that is, do you want clean or dirty electricity? What I mean here is that there are two types of electricity that inverters can produce. Pure sine wave Inverters and Modified sine wave Inverters. The difference is that pure sine wave matches the power to that of which you get from your electricity supplier, it's clean and you can run any appliances safely even sensitive equipment. The modified sine wave is dirty power, you can use this to power a lot of things that don’t have sensitive electronics. Kettle for example fridges, cookers, hot plates, etc. You cannot run led lighting on these Inverters as they are overhead and die within a couple of hours. You have to be careful with some TV PCs as they do n like it either, but I have heard that lot of people use them for this with no problems, but I like to be safe, rather than sorry.TABLE OF CONTENTSCHAPTER ONEIntroductionCHAPTER TWOTransformer FundamentalsCHAPTER THREE3.1 Description Of Components3.2 Capacitors3.2.1 Types of Capacitor3.3 Semi-Conductor Diode3.4 Transistors3.4.1 Bipolar Transistor3.5 Field Effect Transistor (FET)CHAPTER FOUROperation and Design Consideration4.1 Features of the Device4.1.1 Supply Unit4.1.2 Inverter Unit4.1.3 Stepup Transformer Unit4.1.4 Triggering or Switching Unit4.2 Design4.2.1 Required Specification4.2.2 Triggering or Switching Circuit4.2.3 Buffer Stage4.2.4 Transformer Turns RatioCHAPTER FIVE: CONSTRUCTION PROCEDURE AND TESTING5.1 Casing and PackagingCHAPTER SIX: ASSEMBLING OF SECTIONS6.1 Testing of System OperationCHAPTER SEVEN: INSTALLATION OF COMPLETED DESIGNList, Quantity, And Prizes Of Components UsedConclusionCHAPTER ONE1.0 INTRODUCTION 1.0.1 What is an Inverter? An inverter (or power inverter) is electronic circuitry that changes direct current (DC) to alternating current (AC).Direct current is a type of current that flows in only one direction. Using the conventional current flow, direct current is such that electrons leave the power source from the positive terminal (usually marked red) and flows through the circuit and then terminates at the negative terminal (usually marked blue) of the power source. Direct current (DC) is usually gotten from battery cells, solar panels, household generations, etc. VVit Fig 1.1 Graph of DC voltage against timeAn alternating current is one in which the current direction changes with respect to time, i.e it flows in one direction for an amount of time after which it changes direction. In this case, there is no fixed polarity for the terminals of the power supply. This type of current is usually gotten from, public power supply distribution companies, industrial generators, etc.The alternating current graph could take the form of a sine wave, square wave, triangular wave, modified square wave, etc. These graphs are shown in fig. 1.2. T(a) (b) tTViVmax(c) t t T Fig. 1.2 Varied forms of alternating currents (a) sine wave (b) triangular wave (c) square wave (d) modified square wave The power supplied by industrial generators and public distribution companies is usually pure sine wave. But commercial inverters could give output ranging from square wave, modified square wave to pure sine wave. Although pure sine wave is most preferable for electrical equipment, it is usually costly because of the technology involved. The modified square wave is predominant in household inverters. This modified sine wave is manageable for electoral equipment compared to square wave1.0.2BASIC WORKING PRINCIPLES OF INVERTERThe basic difference between an AC and a DC source is that, while an AC alternates its current direction or polarity, a DC has a fixed current direction and polarity. The major work of an inverter, therefore, is to alternate the polarity of the DC power supply terminals.Consider fig 1.3 below. Fig1.3 Basic inverter circuit The circuit consists of a center-tapped step-up transformer, a battery, and a switch. When the switch is such that the negative terminal of the battery is connected to point A, current flows in the primary side of the transformer as shown by the curve ”a”. When this is done the secondary side of the transformer gives power with current flow in the “a” direction. When the switch is reset to connect to point B and the negative terminal of the battery, the current flow in the primary side of the transformer is indicated by curve “b”. that of the secondary side is in curve “b” direction. This arrangement gives out a square wave output. The switching system could be mechanical or electrical. An example of an electromechanical inverter switch is a VIBRATOR. Transistors of different power ratings (depending on the power rating of the inverter) can be used as switches for the circuits. A pure sine wave can be realized with better technology. This is shown in fig 1.4 Fig1.4 Setup for pure sine wave inverter Figure 1.4 Contains A Battery, two Drivers / Motors, A Belt, Power Amplifier, and a Power Transformer The battery supplies power to driver A. This causes its blades to rotate. The belt transmits this rotary motion to driver B. The rotational motion of driver B brings about an alternating current at the terminals of driver B. This alternating current is fed into the power amplifier. The power amplifier combines the DC current from the battery and the AC current from driver B to give an AC with a higher power.While the battery supplies the power (voltage and current), the AC current from driver B causes it to oscillate. The output at the power amplifier is fed into the step-up power transformer which steps up the voltage from 12 volts to 220 voltsModern inverters are mere development of this basic inverter circuit. 1.0.3IMPORTANCE OF INVERTERBelow are some importance of inverter circuit to the engineering and the world at large;1. DC power sources like solar power and batteries can be used for AC appliances with the aid of inverters 2. Inverter encourages the storage of energy which is used in electroshock weapons and uninterruptible power supply (UPS) 3. Induction heating which requires high frequency is made possible using inverters. 4. Due to the DC/AC conversion process of inverters, skin effect, number, and size of conductors are reduced which invariably reduces cost in HVDC transmission1.1 HISTORY AND APPLICATIONS OF INVERTER1.1.1 History of an InverterInverter dates back to the late nineteenth century through the middle twentieth century. Although the term inverter is attributed to David Prince who publish an article on the inverter in the GE Review (vol. 28, No.10, P. 678 – 81) in 1925, it is not certain if he was the one who coined the term. DC/AC power conversion in its early days was accomplished using rotary converters. As technology improved, vacuum tubes and gas-filled tubes were used as switches for inverter circuits.The name inverter can be related to the electromechanical forms of switching used in its early days.1.1.2 Applications of InverterAn inverter circuit is used in the following areas of electrical and electronic engineering;Solar power supply Power grid and HVDC power transmission Induction heating Electric motor speed control Electric shock weapons Uninterruptible power supply (UPS)1.2 AIMS AND OBJECTIVE1.2.1 AIMS The aim of this project is to design and construct an inverter.1.2.2OBJECTIVEThe objective of this project is to;Design an inverter Construct an inverter Test the inverter.1.2.3METHODOLOGY1.Literature review and design of the inverter: Literature will be reviewed to obtain the working principles and circuit diagram after which a design will be made to ascertain the rating and parameters of the different components involved in the inverter.2. Construction of the inverter: The circuit will be constructed firstly on a breadboard before soldering.3. Testing of the circuit: The circuit will be tested with appliances according to the calculated rating of the inverter..