Eee Thesis

SWITCHED COUPLED QUASI Z SOURCE INVERTER FOR PHOTOVOLTAIC POWER GENERATION SYSTEM Submitted by

S. ABIRAMI

REGISTER NO : 14TE0203

A. MARGRET

REGISTER NO : 14TE0253

D.PRIYANKA

REGISTER NO : 14TE0276

SINDHUJA SANKAR

REGISTER NO : 14TE0296 Under the guidance of

Mr. A.Janagiraman M.E (Assistant Professor, EEE Department) In partial fulfilment of the requirement for the award of degree of

BACHELOR OF TECHNOLOGY in DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

SRI MANAKULA VINAYAGAR ENGINEERING COLLEGE, MADAGADIPET, PUDHUCHERRY SUBMITTED TO PONDICHERRY UNIVERSITY APRIL 2018

SRI MANAKULA VINGYAR ENFGINNERING COLLEGE MADAGADIPET, PUDUCHERY 605107 DEPARTMENT OF ELECTRICL AND ELECTRONICS ENGINEERING BONAFIDE CERTIFICATE This is to certify that this project work entitled “SWITCHED COUPLED QUASI Z SOURCE INVERTER PHOTOVOLTAIC POWER GENERATION SYSTEM” is a bonafide work done by ABIRAMI.S [REGISTER NO: 14TE0203], MARGRET.A [REGISTER NO: 14TE0253], PRIYANKA.D [REGISTER NO: 14TE0276], SINDHUJA SANKAR [REGISTER NO: 14TE0296] in partial fulfilment of the requirement for the award of B.Tech., Degree in Electrical and Electronics Engineering by Pondicherry university during the academic year 2017-2018. This project has not been submitted for the ward any other degree.

PROJECT GUIDE

HEAD OF DEPARTMENT

(Mr. A.Janagiraman, M.E)

(Dr. S. Anbumalar M.E., Ph.D)

Viva –voce examination held on ………………

INTERNAL EXAMINER

EXTERNAL EXAMINER

ACKNOWLEDGEMENT

We are highly elated to acknowledge our respect and heartfelt gratitude to our respectable founder chairman Shri. N. Kesavan, chairman & managing director Mr.M.Dhanasekaran and vice chairman Mr.S.V.Sugumaran for their untiring encouragement and help to commit our project in the perfect situation. We are greatly indebted to our beloved Director cum Principal Dr.V.S.K. Venkatachalapathy, and our respected secretary Dr. K. Narayanaswamy, SMVEC Trust for extending the college facilities for our project and for his immense help, unswerving motivation and lively deliberation in spite of his busy schedule. We take this opportunity to express our thanks to Dr. S. Anbumalar M.E., Ph.D., Head of the Department, Electrical and Electronics Engineering, for her patronage. We express our heartfelt gratitude to our beloved guide Mr.A.JanagiramanM.E., Assistant professor, Department of Electrical and Electronics Engineering for his constant inducement and encouragement. He has been a great source of valuable guidance, suggestions and constructive criticism during the course of the project work. We are grateful to Ms.P.Jamuna M.Tech., Project Coordinators for their continuous encouragement and also to all the staff members of Electrical and Electronics Department for their valuable suggestions throughout the project.

We also express our sincere thanks to all non-teaching and administrative staff members For their valuable assistance throughout the project work.

We thank our parents and friends for their continuous support. We are grateful to almighty for giving us the strength, courage and determination to complete this project successfully.

ABSTRACT The recent trend has proved that solar energy the best conventional source of energy to meet the present the demand of electricity, but still the reduced usage of solar energy is mainly due to cost and lack of continuous supply from the PV cells. In order to obtain continuous current and simultaneously reduce the cost by using low component rating, A new topology of quasi – Z source inverter (QZSI) is designed from the traditional Z source inverter (ZSI). This quasi – Z source network is capable to both buck and boost the voltage provided, the single stage inversion occurs with high efficiency and reliability and provides constant dc current from source. The network is coupled to the inverter that provides ac to the load. The above proposed scheme is verified in MATLAB/SIMLINK simulated and the result obtained is validated.

CHAPTER-1 INTRODUCTION

1.1 NEED FOR PHOTOVOLTAIC POWER GENERATION Generally, the photovoltaic power generation system has been considered as the most developing alternative source of energy due to the abundant energy available in this world that can lighten the rapid consumption of fossil fuels. Still there is a reduction in the use of solar energy, is mainly due to the cost and lack of continuous supply from PV cells. Hence this is a very promising technology and nowadays is growing thanks to the new developments in the photovoltaic materials and the power converters. Despite the improvements in the materials used in the solar cell, the power converter are the vital part of the overall system. Since they transform PV panel energy into a usable electric source. As, the voltage source inverter is a buck converter, it needs the high input voltage than output so inverter rating must be high. So, when PV panel is used with inverter it leads to low rating and it does not produce desired output when connected to the load. The main problem with solar power that has stifled its use is the fact that energy production only takes place when the sun is shining. Large storage systems need to be developed to provide a constant and reliable source of electricity when the sun isn’t shining at night or when a cloud goes overhead. When solar panels are not producing energy, it takes longer to recoup their installation and maintenance cost. The Z source inverter (ZSI) can be used with solar panel for various applications as it does voltage boosting and inversion in single stage. Quasi z source inverter has been developed from z source inverter and the proposed system analyzes the solar panel that gives the input to the quasi z source inverter. Therefore, by using this topology the inverter draws a constant current from PV array irrespective of varied temperature and radiation from the sun. It also provides low component rating and a constant DC current from source and it provides single stage of voltage.

1.2 LITRATURE SURVEY SIMULATION OF Z-SOURCE INVERTER WITH LOW VOLTAGE STRESS ON BALENCING CAPACITOR Seema N. Kharat1, K. Chandra Obula Reddy2 1PG Scholar, 2Assistant professor Department Electrical Engineering, MSS’s CET, Jalna,(India)

The Z source invertor has been proved best suited for PV application in this paper, that describes the performance of the new topology of quasi Z source and analyse the one voltage fed topology and applied it to PV power generation systems. This network draws constant current and handles wide range of voltage. It also featured for both buck and boost process. This scheme is verified in MATLAB/SIMLINK simulated and output is validated.

Quasi-Z-Source Inverter-Based Photovoltaic Generation System With Maximum Power Tracking Control Using ANFIS Haitham Abu-Rub,Senior Member, IEEE, Atif Iqbal, Senior Member,IEEE, Sk. Moin Ahmed, Member,IEEE, Fang Z. Peng,Fellow,IEEE, Yuan Li,Member,IEEE, and Ge Baoming, Member,IEEE

This paper proposes an artificial – intelligence –based solution to interface and deliver the maximum power from a photovoltaic (PV) power generation system in standalone operation. The interface between the PV dc source and the load is accomplished by a quasi-Z-source inverter (qZSI).The maximum power delivery to the load is ensured by an adaptive neuro-fuzzy inference system (ANFIS) based on maximum power point tracking (MPPT). This system offers an extremely fast dynamic response with high frequency. . The proposed technique is tested for isolated load conditions. Simulation and experimental approaches are used to validate the proposed scheme.

An Energy-Stored Quasi-Z-Source Inverter for Application to Photovoltaic Power System Baoming Ge, Member, IEEE, Haitham Abu-Rub, Senior Member, IEEE, Fang Zheng Peng, Fellow, IEEE, Qin Lei, Student Member, IEEE, Aníbal T. de Almeida, Senior Member, IEEE,

Fernando J. T. E. Ferreira, Senior Member, IEEE, Dongsen Sun, and Yushan Liu, Student Member, IEEE

This paper depicts the battery operation that can balance the fluctuation of photovoltaic (PV) power injected to the grid/load, but there is certain limitation in the existing topology of discontinues conduction mode during battery discharge. To overcome this demerits an energy stored quasi Z source network is introduced. They can control the inverter output power, track the PV panel’s maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. The above is scheme is verified in MATLAB/SIMLINK and compared with the exiting and output result are validated.

Trans-Z-Source Inverters Wei Qian, Fang Zheng Peng, Fellow, IEEE, and Honnyong Cha, Member, IEEE This paper extends the impedance source (Z- source) inverters concept to the transformer based Z-source (trans - Source)inverters. The one dominant character of both buck and boost has failed in traditional Z source inverter. . In the proposed four trans-Z-source inverters, all the impedance network consist of a transformer and one capacitor. While maintaining the main features of the previously presented Z-source network, the new networks exhibit some unique advantages, such as the increased voltage gain and reduced voltage stress. Simulation and experimental results of the voltage-fed and the current-fed trans-ZSIs are provided to verify the analysis

Quasi-z-source inverter for photovoltaic power generation systems Pravin P. Kalubarme ME EPS Student/MSS’s CET/Jalna/ India Prof. Santhosh Kompelli.

This paper reports that ZSI is suitable for residential PV system because of the capability of voltage boost and inversion in single stage. By using the new quasi-Z-Source topology, the inverter draws a constant current from the PV array and is capable of handling a wide input voltage range. It also features lower component ratings and reduced source stress compared to the

traditional

ZSI.

It

is

demonstrated

from

the

theoretical

analysis

and

MATLAB/SIMULATION results that the proposed q-ZSI can realize voltage buck or boost and dc-ac inversion in a single stage with high reliability and efficiency, which makes it well suited for PV power system.

1.3 ORGNIZATION OF THESIS CHAPTER 1: Deals with overview of project CHAPTER 2: Block diagram and its description CHAPTER 3: Circuit Diagram and its description CHAPTER 4: Design calculation of proposed system CHAPTER 5: Developed SIMULINK model and results CHAPTER 6: Hardware implementation and Results CHAPTER 7: Conclusion and Future scope

CHAPTER 2

2.1 BLOCK DIAGRAM FOR PROPOSED SYSTEM The proposed scheme of quasi-z source inverter (Q-ZSI) is depicted in block diagram below, which describe the structure of the system. The input supply is give through the solar panel and coupled with network and connected to the inverter to give alternating current to the load efficiently.

Fig.1 Block Diagram for Proposed System

2.2 DESCRIPTION OF BLOCK DIAGRAM 2.2.1 OUTPUT OF PV ARRAY The PV Array generates the DC voltage at its output side. This DC voltage is used as input to the quasi-Z-Source network.

2.2.2 FILTERS It consists of a LC circuit to remove the ripple components raised during DC to AC conversion. 2.2.3 QUASI -Z- SOURCE NETWORK A Quasi-Z-Source network is derived from the traditional Z-Source network. The QZSI inherits all the advantages of the ZSI, which can realize buck/boost, inversion and power conditioning in a single stage with improved reliability q-ZSI has the unique advantages of lower component ratings and constant dc current from the source. 2.2.4 VOLTAGE SOURCE INVERTER The Voltage Source Inverter is the one in which the DC source has small or negligible impedance. In other words a Voltage Source Inverter has stiff DC source voltage at its input terminals. A large capacitor is connected at the input terminals tends to make the input DC voltage constant. This capacitor also suppresses the harmonics fed back to the source.

The

Voltage Source Inverter is widely used. 2.2.5 PULSE GENERATOR AND DRIVER UNIT To turn on the MOSFET it is necessary to inject the gate pulses to trigger on. These triggering pulses are generated by the pulse generator. These pulses are fed to each MOSFET which is to be turned on. In other words the driver unit directs the gate pulse to required MOSFET. 2.2.6 LOAD An induction motor or a synchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. It can therefore be made without electrical connections in the rotor. The single phase induction motor is most frequently used in clocks, drills, pumps, washing machines, etc.

CHAPTER 3 CIRCUIT DIAGRAM 3.1 DESCRIPTION OF CIRCUIT DIAGRAM

The overall circuit diagram is designed below for the above proposed scheme, which depicts the performance of the system.

Fig. 2 Overall Circuit Diagram

3.2 CIRCUIT CONFIGURATION AND A SMALL DESCRIPTION

The Z source inverter (ZSI) is reported to be suitable for the residential PV system because of the capability of voltage boost and inversion in single stage. Recently many new system of quasi Z source inverter (Q-ZSI) which has been derived from the original Z source inverter. The quasi Z source inverter draws a constant current from the PV panel and also capable to handle wide input voltage shown in Fig.3. This network utilizing the shoot through state to boost DC bus voltage by gating both the upper and lower switches of the phase lag and produce desired output. This system improves the reliability by shoot through due to misgating which no longer can destroy the circuit.

Thus it provides a low cost, reliable and high efficiency single stage structure for buck and boost conversion, also it inherits all the qualities and advantage of Z source inverter. It possesses continuous input current, reduced stress and lower component rating.

3.3 SOLAR PANELS 3.3.1 INTRODUCTION Every day, the sun radiates (sends out) an enormous amount of energy called solar energy. It radiates more energy in one day than the world uses in one year. This energy comes from within the sun itself. Like most stars, the sun is a big gas ball made up mostly of hydrogen and helium gas. The sun makes energy in its inner core in a process called nuclear fusion. It takes the sun’s energy just a little over eight minutes to travel the 93 million miles to Earth. Solar energy travels at the speed of light, or 186,000 miles per second, or 3.0 x 108 meters per second. Only a small part of the visible radiant energy (light) that the sun emits into space ever reaches the Earth, but that is more than enough to supply all our energy needs. Every hour enough solar energy reaches the Earth to supply our nation’s energy needs for a year! Solar energy is considered a renewable energy source due to this fact. Today, people use solar energy to heat buildings and water and to generate electricity. Solar energy accounts for a very small percentage of U.S. energy less than one percent. Solar energy is mostly used by residences and to generate electricity.

3.3.2 SOLAR COLLECTOR Heating with solar energy is not as easy as you might think. Capturing sunlight and putting it to work is difficult because the solar energy that reaches the Earth is spread out over a large area. The sun does not deliver that much energy to any one place at any one time. The amount of solar energy an area receives depends on the time of day, the season of the year, the cloudiness of the sky, and how close you are to the Earth’s Equator. A solar collector is one way to capture sunlight and change it into usable heat energy. A closed car on a sunny day is like a solar collector. As sunlight passes through the car’s windows, it is absorbed by the seat covers, walls, and floor of the car. The absorbed light changes into heat. The car’s windows let light in, but they don’t let all the heat out. A closed car can get very hot.

3.3.3 PHOTOVOLTAIC ELECTRICITY Photovoltaic comes from the words photo, meaning light, and volt, a measurement of electricity. Sometimes photovoltaic cells are called PV cells or solar cells for short. You are probably familiar with photovoltaic cells. Solar-powered toys, calculators, and roadside telephone call boxes all use solar cells to convert sunlight into electricity. Solar cells are made up of silicon, the same substance that makes up sand. Silicon is the second most common substance on Earth. Solar cells can supply energy to anything that is powered by batteries or electric power. Electricity is produced when radiant energy from the sun strikes the solar cell, causing the electrons to move around. The action of the electrons starts an electric current. The conversion of sunlight into electricity takes place silently and instantly. There are no mechanical parts to wear out. Compared to other ways of making electricity, photovoltaic systems are expensive and many panels are needed to equal the electricity generated at other types of plants. It can cost 10 to 30 cents per kilowatt-hour to produce electricity from solar cells. Most people pay their electric companies about 12.7 cents per kilowatt-hour for the electricity they use, and large industrial consumers pay less. Solar systems are often used to generate electricity in remote areas that are a long way from electric power lines. In 2015, the Desert Sunlight solar project in California opened. It is the largest photovoltaic plant in the world, generating 550 megawatts of electricity enough to power over 150,000 homes.

3.3.4 SOLAR ELECTRICITY Solar energy can also be used to produce electricity. Two ways to make electricity from solar energy are photovoltaics and solar thermal systems.

3.3.5 SOLAR THERMAL ELECTRICITY Solar cells, solar thermal systems, also called concentrated solar power (CSP), use solar energy to produce electricity, but in a different way. Most solar thermal systems use a solar collector with a mirrored surface to focus sunlight onto a receiver that heats a liquid. The superheated liquid is used to make steam to produce electricity in the same way that coal plants do. There are CSP plants in California, Arizona, Nevada, Florida, Colorado, and Hawaii. Some of the world’s largest CSP facilities are located in California. Solar energy has great potential

for the future. Solar energy is free, and its supplies are unlimited. It does not pollute or otherwise damage the environment. It cannot be controlled by any one nation or industry. The technology to harness the sun’s enormous power, we may never face energy shortages again Solar Panels absorb sunlight as a source of energy to generate electricity or heat. Photovoltaic modules constitute the photovoltaic array of a photovoltaic system that generates and supplies electricity. Each module is rated by its DC output power under standard test conditions, and typically ranges from 100 to 360 Watts. The efficiency of a module determines the area of a module given the same rated output an 8% efficient 230 W module will have twice the area of a 16% efficient 230 W module. There are a few commercially available solar modules that exceed. Efficiency of 22%and reportedly also exceeding 24%.The majority of modules use wafer based crystalline silicon cells thin-film cells. Cells must also be protected from mechanical damage and moisture. Most modules are rigid, but semi-flexible ones based on thin-film cells are also available. The cells must be connected electrically in series, one to another. Most of photovoltaic modules use MC4 connectors type to facilitate easy weatherproof connections to the rest of the system. Module electrical connections are made in series to achieve a desired output voltage or in parallel to provide a desired current capability. Some special solar PV modules include concentrators in which light is focused by lenses or mirrors onto smaller cells. This enables the use of cells with a high cost per unit area (such as gallium arsenide) in a cost-effective way. Depending on construction, photovoltaic modules can produce electricity from a range of frequencies of light, but usually cannot cover the entire solar range. Most parts of a solar module can be recycled including up to 95% of certain semiconductor materials or the glass as well as large amounts of ferrous and non-ferrous metals.

3.3.6 PHOTOVOLTAIC CELL The collection of light-generated carriers does not by itself give rise to power generation. In order to generate power, a voltage must be generated as well as a current. Voltage is generated in a solar cell by a process known as the “photovoltaic effect.” The collection of light-generated carriers by the p-n junction causes a movement of electrons to the n-type side and holes to the p type side of the junction. Under short circuit conditions, the carriers exit the device as light generated current. PV solar panels generate direct current (DC) electricity. With DC electricity, electrons flow in one direction around a circuit.

3.3.7 COMPONENTS OF PV CELL The most important components of a PV cell are two layers of semiconductor material commonly composed of silicon crystals. On its own, crystallized silicon is not a very good conductor of electricity, but when impurities are intentionally added a process called doping. The stage is set for creating an electric current. The bottom layer of the PV cell is usually doped with boron, which bonds with the silicon to facilitate a positive charge, while the top layer is doped with phosphorus, which bonds with the silicon to facilitate a negative charge .The surface between the resulting "p-type" and "n-type" semiconductors is called the P-N junction. Electron movement at this surface produces an electric field that allows electrons to flow only from the p-type layer to the n-type layer. When sunlight enters the cell, its energy knocks electrons loose in both layers. Because of the opposite charges of the layers, the electrons want to flow from the n-type layer to the p-type layer. But the electric field at the P-N junction prevents this from happening. The presence of an external circuit, however, provides the necessary path for electrons in the n-type layer to travel to the p-type layer. The electrons flowing through this circuit typically thin wires running along the top of the n-type layer provide the cell's owner with a supply of electricity. Most PV systems are based on individual square cells a few inches on a side. Alone, each cell generates very little power (a few watts), so they are grouped together as modules or panels. The panels are then either used as separate units or grouped into larger arrays.

3.3.8 WORKING PRINCIPLE OF SOLAR CELL The working principle of solar cells is based on the photovoltaic effect, i.e. the generation of a potential difference at the junction of two different materials in response to electromagnetic radiation. The photovoltaic effect is closely related to the photoelectric effect, where electrons are emitted from a material that has absorbed light with a frequency above a material-dependent threshold frequency. In 1905, Albert Einstein understood that this effect can be explained by assuming that the light consists of well defined energy quanta, called photons. The energy of such a photon is given by E = hν, (3.1) where h is Planck’s constant and ν is the frequency of the light.

Absorption of a photon in a material means that its energy is used to excite an electron from an initial energy level Ei to a higher energy level Ef.. Photons can only be absorbed if electron energy levels Ei and Ef are present so that their difference equals to the photon energy, hν = Ef − Ei . In an ideal semiconductor electrons can populate energy levels below the so-called valence band edge, EV, and above the so called conduction band edge, EC. Between those two bands no allowed energy states exist, which could be populated by electrons. Hence, this energy difference is called the bandgap, Eg = EC − EV. If a photon with an energy smaller than Eg reaches an ideal semiconductor, it will not be absorbed but will traverse the material without interaction. In a real semiconductor, the valence and conduction bands are not flat, but vary depending on the so-called k-vector that describes the crystal momentum of the semiconductor. If the maximum of the valence band and the minimum of the conduction band occur at the same k vector, an electron can be excited from the valence to the conduction band without a change in the crystal momentum. Such a semiconductor is called a direct bandgap material. If the electron cannot be excited without changing the crystal momentum, we speak of an indirect bandgap material. The absorption coefficient in an direct bandgap material is much higher than in an indirect bandgap material, thus the absorber can be much thinner . If an electron is excited from Ei to Ef , a void is created at Ei . This void behaves like a particle with a positive elementary charge and is called a hole. The absorption of a photon therefore leads to the creation of an electron-hole pair. The radiative energy of the photon is converted to the chemical energy of the electron-hole pair. The maximal conversion efficiency from radiative energy to chemical energy is limited by thermodynamics. This thermodynamic limit lies in between 67% for non concentrated sunlight and 86% for fully concentrated sunlight.

3.3.9 BASIC TYPES OF SOLAR CELLS •

SINGLE CRYSTAL CELLS: These cells are made in long cylinders and sliced into thin wafers. While this process is energy-intensive and uses more materials, it produces the highest efficiency cells, those able to convert the most incoming sunlight to electricity. Modules made from single-crystal cells can have efficiencies of up to 23 percent in some laboratory tests. Single-crystal accounts for a little over one third of the global market for PV.

•

Polycrystalline cells: These cells are made of molten silicon cast into ingots then sliced into squares. While production costs are lower, the efficiency of the cells is lower too with top module efficiencies close to 20 percent. Polycrystalline cells make up around half of the global PV market.

•

Thin film cells: They involve spraying or depositing materials (amorphous silicon, cadmium, telluride, or other) onto glass or metal surfaces in thin films, making the whole module at one time instead of assembling individual cells. This approach results in lower efficiencies, but can be lower cost. Thin film cells are around ten percent of the global PV market.

3.3.10 PV CELLS: PV cells are most commonly made of silicon, and come in two common varieties, crystalline and thin-film cells.

3.3.11 A p-n junction: It is formed by joining p-type (high concentration of hole or deficiency of electron) and n-type (high concentration of electron) semiconductor material. Due to this joining, excess electrons from n-type try to diffuse with the holes of p-type whereas excess hole from p-type try to diffuse with the electrons of n-type. Movement of electrons to the p-type side exposes positive ion cores in the n-type side, while movement of holes to the n-type side exposes negative ion cores in the p-type side, resulting in an electron field at the junction and forming the depletion region.

3.3.12 Photovoltaic effect: The collection of light-generated carriers does not by itself give rise to power generation. In order to generate power, a voltage must be generated as well as a current. Voltage is generated in a solar cell by a process known as the “photovoltaic effect.” The collection of light-generated carriers by the p-n junction causes a movement of electrons to the n-type side and holes to the ptype side of the junction. Under short circuit conditions, the carriers exit the device as lightgenerated current.

3.4 Array Mounting Racks Arrays are most commonly mounted on roofs or on steel poles set in concrete. In certain applications, they may be mounted at ground level or on building walls. Solar modules can also be mounted to serve as part or all of a shade structure such as a patio cover. On roof-mounted systems, the PV array is typically mounted on fixed racks, parallel to the roof for aesthetic reasons and stood off several inches above the roof surface to allow airflow that will keep them as cool as practical. The tilt of sloped rooftop arrays is usually not changed, since this is inconvenient in many cases and sometimes dangerous. However, many mounting racks are adjustable, allowing resetting of the angle of the PV modules seasonally. Tracking – Pole mounted PV arrays can incorporate tracking devices that allow the array to automatically follow the sun. Tracked PV arrays can increase the system’s daily energy output by 25 percent to 40 percent. Despite the increased power output, tracking systems usually are not justified by the increased cost and complexity of the system.

3.5 Battery Bank Batteries store direct current electrical energy for later use. This energy storage comes at a cost, however, since batteries reduce the efficiency and output of the PV system, typically by about 10 percent for lead-acid batteries. Batteries also increase the complexity and cost of the system. Types of batteries commonly used in PV systems are: • Lead-acid batteries • Alkaline batteries

3.5.1 Lead-Acid Batteries Lead-acid batteries are most common in PV systems in general and sealed lead acid batteries are most commonly used in grid-connected systems. Sealed batteries are spill-proof and do not require periodic maintenance. Flooded lead acid batteries are usually the least expensive but require adding distilled water at least monthly to replenish water lost during the normal charging process. There are two types of sealed lead acid batteries: sealed absorbent glass mat and gel cell. AGM lead-acid batteries have become the industry standard, as they are

maintenance free and particularly suited for grid-tied systems where batteries are typically kept at a full state of charge. Gel-cell batteries, designed for freeze-resistance, are generally a poor choice because any overcharging will permanently damage the battery.

3.5.2 Alkaline Batteries To of their relatively high cost, alkaline batteries are only recommended where extremely cold temperatures (-50o F or less) are anticipated or for certain commercial or industrial applications requiring their advantages over lead-acid batteries. These advantages include tolerance of freezing or high temperatures, low maintenance requirements, and the ability to be fully discharged or over-charged without harm.

3.6 Charge Controller A charge controller, sometimes referred to as a photovoltaic controller or battery charger, is only necessary in systems with battery back-up. The primary function of a charge controller is to prevent overcharging of the batteries. Most also include a low voltage disconnect that prevents over-discharging batteries. In addition, charge controllers prevent charge from draining back to solar modules at night. Some modern charge controllers incorporate maximum power point tracking, which optimizes the PV array’s output, increasing the energy it produces.

3.6.1 Types of Charge Controllers There are essentially two types of controllers: shunt and series. A shunt controller bypasses current around fully charged batteries and through a power transistor or resistance heater where excess power is converted into heat. Shunt controllers are simple and inexpensive, but are only designed for very small systems. Series controllers stop the flow of current by opening the circuit between the battery and the PV array. Series controllers may be single-stage or pulse type. Single-stage controllers are small and inexpensive and have a greater loadhandling capacity than shunt-type controllers. Pulse controllers and a type of shunt controller referred to as a multi-stage controller have routines that optimize battery charging rates to extend battery life.

3.7 Energy produced by solar panel Available sunlight will vary depending on where you live but for the sake of an example, if you are getting 5 hours of direct sunlight in a sunny state like California you can calculate it this way: 5 hours x 290 watts (a wattage of a premium solar panel) = 1,450 watts or roughly 1.5 kilowatt-hours (kwh). Thus each solar panel in your system would produce a little over 500-550 kWh of energy per year. All solar panels are rated by the amount of DC (direct current) power they produce under standard test conditions. Solar panel power output is expressed in units of watts (W), and represents the panel’s theoretical power production under ideal sunlight and temperature conditions. Most home solar panels on the market today have power output ratings ranging from 250 to 400 watts, with higher power ratings generally considered preferable to lower power ratings. Pricing in solar is typically measured in dollars per watt ($/W), and the total wattage of your solar panels plays a significant part in the overall cost of your solar system. Power output is an important metric for your home or commercial solar panel system. When you buy or install a solar photovoltaic (PV) energy system, the price you pay is typically based on the total power output of the solar panels in the system (expressed in watts or kilowatts). Solar panel wattage represents a solar panel’s theoretical power production under ideal sunlight and temperature conditions. Wattage is calculated by multiplying volts and amps where volts represents the amount of force of the electricity and amperes (amps) refers to the aggregate amount of energy used. Power output on its own is not a complete indicator of a panel’s quality and performance characteristics. For some panels, their high power output rating is due to their larger physical size rather than their higher efficiency or technological superiority. For example, if two solar panels both have 15 percent efficiency ratings, but one has a power output rating of 250 watts and the other is rated at 300 watts, it means that the 300-watt panel is about 20 percent physically larger than the 250-watt panel. That’s why Energy Sage and other industry experts view panel efficiency as being a more indicative criterion of solar panel performance strength than solar capacity alone. In practical terms, a solar panel system with a total rated capacity of 5kW (kilowatts) could be made up of either 20 250-Watt panels or 16 300Watt panels. Both systems will generate the same amount of power in the same geographic location. Though a 5kW system may produce 6,000 kilowatt-hours (kWh) of electricity every

year in Boston, that same system will produce 8,000 kWh every year in Los Angeles because of the amount of sun each location gets each year. The electricity generated by a solar PV system is governed by its rated power output, but it’s also dependent on other factors such as panel efficiency and temperature sensitivity, as well as the degree of shading that the system experiences and the tilt angle and azimuth of the roof on which it’s installed. As a general rule of thumb, it makes prudent financial sense to install a solar system with as much power output as you can afford (or that your roof will accommodate). That will ensure you maximize your savings and speed up the payback period of your solar energy system.

3.8 Criteria for selecting solar PV panels 3.8.1 Solar panel ratings All solar panels receive a nameplate power rating indicating the amount of power they produce under industry-standard test conditions. Most solar panels on the market have power ratings in the range of 200 to 350 watts. A higher power rating means that the panels are more effective at producing power. The nameplate rating represents the power output under ideal conditions, which most solar power systems won’t experience for more than a few moments at a time. However, solar panel ratings are useful as a way to make consistent comparisons between panels.

3.8.2 Power tolerance As solar panels are manufactured, some unavoidable variations that impact power output are introduced. Power tolerance indicates how the power output of a solar panel might differ from its nameplate rating. They are typically expressed as a plus-or-minus percentage. For example, a 250-watt panel with a +/= 5% power tolerance could actually produce anywhere from 237.5 watts to 262.5 watts under ideal conditions (as 12.5 watts is 5% of 250 watts). A narrower power tolerance range is preferable to a wider one, because it represents more certainty. Power tolerances should be viewed in tandem with solar panel ratings.

3.8.3 Solar cell efficiency Solar panel efficiency represents how effectively a solar panel can convert solar radiation (e.g. sunlight) into electricity. The most efficient solar panels commercially available today have

solar panel efficiency just above 20%. The graphic below shows how dramatically solar panel performance has improved over time. A higher solar panel efficiency rating means a panel will produce more kilowatt-hours of energy per watt of power capacity. Because one high-efficiency panel can generate more electricity than a similarly sized panel with a standard efficiency rating, efficiency is particularly important if you have limited roof space and large energy bills.

3.8.4 Temperature coefficient Although solar panels are designed to love the sun, high heat can actually reduce a solar panel’s capacity to generate power. The temperature coefficient quantifies how a panel’s power capacity decreases at temperatures higher than 77°F, which is the standard temperature at which tests are performed. For example, many standard grade solar panels may produce 1 percent less electricity for every 4°F temperature increase above 77°F. Panels with less sensitive temperature coefficients will perform better over the long term. Check solar panel ratings and reviews carefully for the temperature coefficient, particularly if you live in hotter parts of the country.

3.8.5 Solar panel quality The International Organization for Standardization (ISO) has created quality assurance standards for the manufacturing industry known as the ISO 9000 series. Solar panel manufacturers can be certified ISO 9000-compliant to indicate that they meet those standards. While lack of ISO certification isn’t necessarily an indicator of an inferior product, buying from a certified manufacturer is an indicator of quality. The current and power output of photovoltaic solar panels are approximately proportional to the sun’s intensity. At a given intensity, a solar panel's output current and operating voltage are determined by the characteristics of the load. If that load is a battery, the battery's internal resistance will dictate the module's operating voltage. A solar panel, which is rated at 17 volts will put out less than its rated power when used in a battery system. That’s because the working voltage will be between 12 and 15 volts. Because wattage (or power) is the product of volts multiplied by the amps, the module output will be reduced. For example, a 50-watt solar panel working at 13.0 volts will products 39.0 watts (13.0 volts x 3.0 amps = 39.0 watts)

PV solar panels are very sensitive to shading. Unlike solar thermal panels used in hot water heating that can tolerate some shading, many brands of PV solar panels cannot even tolerate shading from the branch of a leafless tree. Shading obstructions can be from “soft” or “hard” sources. If a tree branch, roof vent, chimney or other item is shading from a distance, the shadow is diffuse or dispersed. These soft sources significantly reduce the amount of light reaching a solar panel’s cells. Hard sources are defined as those that stop light from reaching solar cells, such as a blanket, tree branch, bird dropping sitting directly on top of the glass. If even one full cell is hard shaded, the voltage of that module will drop to half of its un-shaded value in order to protect itself. If enough cells are hard shaded, the module will not convert any energy and will, in fact, become a tiny drain of energy on the entire system. Partial shading of even one cell on a 36-cell solar panel, will reduce its power output. Because all cells are connected in a series string, the weakest cell will bring the others down to its reduced power level. Therefore, whether 1/2 of one cell is shaded, or 1/2 a row of cells is shaded, (as shown above), the power decrease will be the same and proportional to the percentage of area shaded, in this case 50%. When a full cell is shaded, it can consume energy produced by the remainder of the cells, and trigger the solar panel to protect itself. The solar panel will route the power around that series string. If even one full cell in a series string is shaded, as seen on the right, it will likely cause the module to reduce its power level to 1/2 of its full available value. If a row of cells at the bottom of a solar panel is fully shaded, as seen in Figure 7, the power output may drop to zero. The best way to avoid a drop in output power is to avoid shading whenever possible.

3.8.6 Tilt Angle To capture the maximum amount of solar radiation over the course of a year, a solar array should be tilted at an angle approximately equal to a site's latitude, and facing 15 degrees of due south. To optimize winter performance, the solar array can be tilted 15 degrees more than the latitude angle, and to optimize summer performance, 15 degrees less than the latitude angle. At any given instant, an array will output maximum available power when pointed directly at the sun. To compare the energy output of your array to its optimum value, you will need to know the site's latitude, and actual tilt angle of your array--which may be the slope of your roof if your array is flush-mounted. If your solar array tilt is within 15% of the latitude angle, you can expect a reduction of 5% or less in your system's annual energy production. If your solar array tilt is greater than 15 degrees off the latitude angle, the reduction in your system's annual energy

production may fall by as much as 15% from its peak available value. During the winter months at higher latitude, the reduction will be greater.

3.8.7 Standard Test Conditions (STC) STC is the set of criteria that a solar panel is tested at. Since voltage and current change based on temperature and intensity of light, among other criteria, all solar panels are tested to the same standard test conditions. This includes the cells’ temperature of 25℃ (77℉), light intensity of 1000 watts per square meter, which is basically the sun at noon, and the atmospheric density of 1.5, or the sun’s angle directly perpendicular to the solar panel at 500 feet above sea level.

3.8.8 Normal Operating Cell Temperature (NOCT) The solar panel cells are not 77℉. They heat up much hotter than that in the sun, well over 100℉. NOCT takes a more realist view of actual real world conditions, and gives you power ratings that you will likely actually see from your solar system. Instead of 1000 watts per square meter, it uses 800 watts per square meter, which is closer to a mostly sunny day with scattered clouds. It uses an air temperature of 20℃ (68℉), not a solar cell temperature, and includes a 2.24MPH wind cooling the back of a ground mounted solar panel (more common in larger solar fields than a roof mounted residential array). These ratings will be lower than STC, but more realistic.

3.8.9 Open Circuit Voltage (Voc) Open circuit voltage is how many volts the solar panel outputs with no load on it. If you just measure with a voltmeter across the plus and minus leads, you will read Voc. Since the solar panel isn’t connected to anything, there is no load on it, and it is producing no current. This is a very important number, as it is the maximum voltage that the solar panel can produce under standard test conditions, so this is the number to use when determining how many solar panels you can wire in series going into your inverter or charge controller. Voc will potentially be briefly produced in the morning when the sun first comes up and the panels are at their coolest, but the connected electronics haven’t woken up out of sleep mode yet. Remember, fuses and breakers protect wires against over-current, not over-voltage. So, if you put too much voltage into most electronics, you will damage them.

Fig: 3 Rated Output specifications:

3.8.10 Short Circuit Current (Isc) Short Circuit Current is how many amps (i.e. current) the solar panels are producing when not connected to a load but when the plus and minus of the panels wires are directly connected to each other. If you just measure with an ammeter across the plus and minus leads, you will read Isc. This is the highest current the solar panels will produce under standard test conditions. When determining how many amps a connected device can handle, like a solar charge controller or inverter, the Isc is used, generally multiplied by 1.25 for National Electrical Code (NEC) 80% requirements.

3.8.11 Maximum Power Point (Pmax) The Pmax is the sweet spot of the solar panel power output, located at the “knee” of the curves in the graph above. It is where the combination of the volts and amps results in the highest wattage (Volts x Amps = Watts). When you use a Maximum Power Point Tracking MPPT) charge controller or inverter, this is the point that the MPPT electronics tries to keep the volts and amps at to maximize the

power output. The wattage that a solar panel is listed as is the Pmax where Pmax = Vmpp x Impp (see below).

3.8.12 Maximum Power Point Voltage (Vmpp) The Vmpp is the voltage when the power output is the greatest. It is the actual voltage you want to see when it is connected to the MPPT solar equipment (like an MPPT solar charge controller or a grid-tie inverter) under standard test conditions. 3.9 Quasi Network The Quasi Z source network can be used to connect low voltage producing renewable energy sources to connect domestic loads. Two modes of operation are there. Shoot through state and Non-shoot through state. The total time duration can be split into shoot-through and nonshoot through time. So the shoot through duty cycle will come into the picture which is the ratio of shoot through time period and the total time period which find the advantages lower over stress or capacitor rating of C2, continuous input current ,reduction in EMI problems as the circuit have common dc rail between source and load. The main features of the QZS converter is that it can compensate the input voltage variations by providing the boost and buck functions in a single stage. In the QZS inverter, the shootthrough states are used to boost the magnetic energy stored in the dc-side inductors L1 and L2 without short circuiting the dc capacitors C1 and C2. This increase in magnetic energy, in turn provides the boost of the voltage seen on the inverter output during traditional operating states. If the input voltage is high enough, the shoot-through states are eliminated, and the QZS inverter begins to operate as a traditional VSI. Its internal impedance network connects the converter main circuit to the power source or load. The quasi Z- source inverter consists of two inductors L1 and L2 and two capacitors C1 and C2. The inductor present in the quasi Z-source inverter reduces the source current. The capacitor voltage is lower than in case of Z- source inverter.

Fig. 4 Quasi Network

The quasi Z-source network connected the converter to the dc source and load. The dc source can be a battery, fuel cell, photovoltaic cell and load can be inductor, capacitor, resistor, or a combination of these. The continuous quasi Z- source inverter provides an earthing between the dc –link and input source, by which there is a reduction in common mode, noise can occur. The low voltage stress is obtained on the capacitors. In the discontinuous mode of quasi Z- source inverter, the aim is to obtain the low voltage stress on the capacitors C1 and C2 again. This low voltage stress on capacitors results in more space saving designs. There are nine switching states (vector): six effective states, two additional zero states and one direct zero state. The direct zero state and traditional zero state will not affect output voltage. In the active state, only one device conducts in each phase leg.

3.10 INVERTER 3.10.1 INTRODUCTION A device which converts dc power to ac power of desired output frequency is called as inverter. The output voltage can be fixed or varied or fixed or variable frequency. A typical power inverter requires a relatively stable dc power source capable of supplying a current for the intended power demands of the system. For low and medium outputs transistorized inverters are used. The inverter gain is the ratio of output voltage to dc input voltage.

DC input voltage

INVERTER

AC input voltage

For low and medium power applications, square wave or quasi square voltages can be obtained as inverter output and for high power applications distorted sinusoidal waveforms can be obtained as inverter output. The input voltage depends on the design and the purpose of the inverter. Example includes:

•

12V DC, for smaller consumer and commercial inverter that typically run from a rechargeable 12V lead acid battery or automotive electrical outlet.

•

24, 36 and 48 V DC, which are common standards for home energy systems.

•

200 to 400 V DC, when power is from photovoltaic solar panels.

•

300 to 450 V DC, when power is from electric vehicle battery packs in vehicle to-grid systems.

3.10.2 TYPES OF INVERTER Based on the commutation, the inverters are classified into: •

Line commutated inverters

•

Load commutated inverters

•

Self commutated inverters

•

Forced commutated inverters Based on the methods of connections:

•

Series inverters

•

Parallel inverters

•

Bridge inverters The Bridge inverters can be further classified into:

•

Single phase half bridge inverter

•

Single phase full bridge inverter

•

Full bridge inverter

Based on the number of phases: •

Single phase inverters

•

Three phase inverters Inverters can be broadly classified into

•

Voltage source inverters

•

Current source inverters Inverters is basically classified into:

•

Square wave

•

Sine wave

•

Modified sine wave

3.10.3 SQUARE WAVE This is one of the simplest waveforms an inverter design can produce and is best suited to low-sensitivity applications such as lighting and heating. Square wave output can produce "humming" when connected to audio equipment and is generally unsuitable for sensitive electronics.

3.10.4 SINE WAVE A power inverter device which produces a multiple step sinusoidal AC waveform is referred to as a sine wave inverter. To more clearly distinguish the inverters with outputs of much less distortion than the modified sine wave (three step) inverter designs, the manufacturers often use the phrase pure sine wave inverter. Almost all consumer grade inverters that are sold as a "pure sine wave inverter" do not produce a smooth sine wave output at all ,just a less choppy output than the square wave (two step) and modified sine wave (three step) inverters. However, this is not critical for most electronics as they deal with the output quite well. Where power inverter devices substitute for standard line power, a sine wave output is desirable because many electrical products are engineered to work best with a sine wave AC power source. The standard electric utility provides a sine wave, typically with minor imperfections but sometimes with significant distortion.

AC motors directly operated on non-sinusoidal power may produce extra heat, may have different speed-torque characteristics, or may produce more audible noise than when running on sinusoidal power.

3.10.5 MODIFIED SINE WAVE The modified sine wave output of such an inverter is the sum of two square waves of each one of which is phase shifted 90 degrees relative to the other. The result is three level waveform with equal intervals of zero volts; peak positive volts; zero volts; peak negative volts and then zero volts. This sequence is repeated. The resultant wave very roughly resembles the shape of a sine wave. Most inexpensive consumer power inverters produce a modified sine wave rather than a pure sine wave. The waveform in commercially available modified-sine-wave inverters resembles a square wave but with a pause during the polarity reversal. Switching states are developed for positive, negative and zero voltages. Generally the peak voltage of the RMS voltage ratio does not maintain the same relationship as for a sine wave. The DC bus voltage may be actively regulated, or the "on" and "off" times can be modified to maintain the same RMS value output up to the DC bus voltage to compensate for DC bus voltage variations. The ratio of on to off time can be adjusted to vary the RMS voltage while maintaining a constant frequency with a technique called pulse width modulation (PWM). The generated gate pulses are given to each switch in accordance with the developed pattern to obtain the desired output. Harmonic spectrum in the output depends on the width of the pulses and the modulation frequency. When operating induction motors, voltage harmonics are usually not of concern; however, harmonic distortion in the current waveform introduces additional heating and can produce pulsating torques.

3.10.6 SINGLE PHASE INVERTER

The single phase requires two wires for completing the circuit, i.e., the conductor and the neutral. The conductor carries the current and the neutral is the return path of the current. The single phase supplies the voltage up to 230 volts. It is mostly used for running the small appliances like a fan, cooler, grinder, heater, etc.

A frequency inverter provides many benefits including: Soft starting of the motor & load reducing mechanical stresses & reduced water hammer with pumps. •

Significantly reduce the starting current, from 600-800% down to <110-150% of the motors rated FLC.

•

Automation & process control using the built-in electronics to provide constant pressure flow systems for irrigation or other pumping applications.

•

Ability to control the speed of the motor.

•

Energy Savings: Substantial energy savings may be achievable for Fan & Pump loads.

3.10.7 The Power, Motor & Inverter Combination The frequency inverter required will be dependent upon both the motor and the power source available. The general rule to remember is that a frequency inverter can convert single phase into three phase power but, it cannot provide a higher voltage out than what you put in. There are basically 4 situations you may have: Power Supply Motor Comments 220V single Phase

220V Delta

220V inverter; connect motor for 220V Delta

/ 415V Star 220V single Phase

415V Delta

Motor suitable for 415V only, will need step-up transformer to increase input voltage to >415V and a 415V inverter with DC bus choke.

480V single phase 415V Delta

480V inverter with DC bus choke; connect motor for

Single Wire Earth

415V Delta

Return 480V single phase 220V Delta

480V inverter with DC bus choke; connect motor for

Single Wire Earth

415V Star

Return

/ 415V Star

3.10.8 The inverter The standard frequency inverter is designed to operate from both a single phase & three phase power supply making it ideal for Single Wire Earth Return Line or single phase supply systems. •

The standard frequency inverter can operate from a 480VAC single phase power supply (Single Wire Earth Return) and provide a controlled 415V three phase output to the motor.

•

The standard frequency inverter (or equivalent) can operate from a 220VAC single phase power supply and provide a controlled 220V 3 phase output to the motor.

When selecting the frequency inverter it is important to determine the motors full load current at the voltage in which it will operate. To do this, it is useful to know the relationship between star and line voltages & currents.

This is especially important when a 415V star / 220V Delta motor is being used on a single phase 220V power system.

Eg. 1.5kW; 3.4Amps 415V star

Star Connected IL =

IP

VL = 3xVP

Fig.5 Three Phase Star Connected

3.10.9 Delta Connected VL = VP IL = 3 x IP

Fig. 6 Three Phase Delta Connected

Therefore, the Line current or Full Load Current of the motor when connected in single phase 220V Delta is 5.9Amps. A frequency inverter capable of a continuous output of 5.9 Amps is required.

3.10.10 Issues of using inverters on Single Phase Power Supplies The operation of an inverter on a single phase power line is simple, but you do need be aware of some of the issues and how they may be addressed.

1. EMC Compliance All inverters satisfy the requirements of the certain standards. To achieve these standards it is necessary to install the equipment as per the inverter manufacturer’s instructions. This may require screened frequency inverter cables from the inverter to the motor. Additional measures may be required for installations which may be sensitive to RFI. Additional measures & alternatives to screened frequency inverter cables are available such as High Performance Output Filter.

2. Harmonics All inverters produce some form of harmonics on the line power, which is significantly increased when operating on a single phase power supply and particularly so, on Single Wire Earth Return or rural environments where the loading on smaller supplies may be relatively high. A DC bus choke is mandatory for inverters operating on a Single Wire Earth Return supply. The sizing of the transformer and the inverter/motor loading on the power supply needs to be taken into consideration when concerned about harmonics. The effect of excessive harmonics may cause overheating of electrical components such as transformers and cables. For the smaller motors operating from a 220V 1Phase power supply, harmonics are some what lower and a DC bus choke may not be required.

3. Temperature rating Single Wire Earth Return line systems only occur in rural areas, where higher ambient temperatures may be experienced, the ambient temperature must be considered. Some manufacturers offer frequency inverters with a continuous rating of 50degC ambient. An IP66 enclosed frequency inverter is also available so the equipment can be direct wall mounting without further enclosing. This promotes better cooling and lower internal operating temperatures.

4. DC Bus Choke A DC Bus choke is mandatory for operation on a 480V Single Wire Earth Return supply and on some single phase 220V installations depending on the motor size. There are numerous benefits provided by a DC bus choke which include:

•

Reduction of Power Line Harmonics

•

Improved Power Factor

•

Transient Filter

•

Reduce peak inrush currents

5. Supply Current Capacity Since the inverter acts as an inverter and produces a 3 Phase power supply from a 1 Phase supply, the current is expected to be higher on the input then the output. It is therefore important to determine what level of supply current is required for the intended motor. As a guide the RMS AC line current to be allowed for, is 1.84 times the motor phase current.

6. Frequency inverter Rating When a frequency inverter is operating from a single phase Single Wire Earth Return supply, the standard frequency inverter must be rated accordingly. Other considerations when selecting the most suitable frequency inverter is the ambient temperature and the type of load. Your inverter manufacturers can assist with selecting the correct frequency inverter for your application. The frequency inverter should be selected based on the full load current in the manner which the motor is connected.

7. Motor Suitability The motor should be suitable for operation on a frequency inverter and comply with certain standards.

3.10.11 Mode analysis of inverter

•

Fig: 7 Mode diagram of inverter

3.10.12 Three phase inverter The three phase system consist four wires, three conductors and one neutral. The conductors are out of phase and space 120º apart from each other. The three phase system is also

used as a single phase system. For the low load, one phase and neutral can be taken from the three phase supply.

Fig: 9 Three phase inverter The three phase supply is continuous and never completely drops to zero. In three phase system power can be drawn either in a star or delta configuration. The star connection is used for long distance transmission because it has neutral for the fault current.

Fig: 10 star connection

The delta connection consists three phase wires and no neutral.

Fig: 11 Delta Connection

Three phase inverters are used for variable-frequency drive applications and for high power applications such as HVDC power transmission. A basic three phase inverter consists of three single-phase inverter switches each connected to one of the three load terminals. For the most basic control scheme, the operation of the three switches is coordinated so that one switch

operates at each 60 degree point of the fundamental output waveform. This creates a line-to-line output waveform that has six steps. The six-step waveform has a zero-voltage step between the positive and negative sections of the square-wave such that the harmonics that are multiples of three are eliminated as described above. When carrier-based PWM techniques are applied to six step waveforms, the basic overall shape, or envelope, of the waveform is retained so that the 3rd harmonic and its multiples are cancelled.

Basis

For Single Phase

Three Phase

Comparison

Definition

The power supply through one conductor.

The power supply through three conductors.

Wave Shape

Number of wire.

Require two wires for completing Requires four wires for completing the circuit. the circuit.

Voltage

Carry 230V

Carry 415V

Phase Name

Split phase

No other name

Power

Transfer Minimum

Maximum

Capability

Network

Simple

Complicated

Power Failure

Occurs

Do not occur

Loss

Maximum

Minimum

Efficiency

Less

High

Economical

Less

More

Uses

For home appliances.

In large industries and for running heavy loads.

Power

Supply

Connection

Fig: 12 Comparison of single phase and three phase

3-phase inverter switching circuit showing 6-step switching sequence and waveform of voltage between terminals A and C (23-2 states). To construct inverters with higher power ratings, two six-step three phase inverters can be connected in parallel for a higher current rating or in series for a higher voltage rating. In either case, the output waveforms are phase shifted to obtain a 12-step waveform. If additional inverters are combined, an 18-step inverter is obtained with three inverters etc. Although inverters are usually combined for the purpose of achieving increased voltage or current ratings, the quality of the waveform is improved as well. •

In single phase supply, the power flows through one conductor whereas the three phase supply consists three conductors for power supply.

•

The single phase supply requires two wires (one phase and one neutral) for completing the circuit. The three phase requires three phase wires and one neutral wire for completing the circuit.

•

The single phase supplies the voltage up to 230V whereas the three phase supply carries the voltage up to 415V.

•

The maximum power is transferred through three phases as compared to single phase supply.

•

The single phase has two wire which makes the network simple whereas the three phase network is complicated as it consists four wires.

•

The single phase system has only one phase wire, and if the fault occurs on the network, then the power supply completely fails. But in three phase system the network has three phases, and if the fault occurs on any one of the phases, the other two will continuously supply the power.

•

The efficiency of the single phase supply is less as compared to three phase supply. Because the three phase supply requires less conductor as compared to single phase supply for the equivalent circuit.

•

The single phase supply requires more maintenance and become costly as compared to three phase supply.

•

The single phase supply is mostly used in the house and for running the small loads. The three phase supply is used in large industries and for running the heavy loads.

•

The star connection of the three phase allows the use of two different voltages (i.e., the 230 volts and the 415 volts). The 230V is supplied by using the one phase and one neutral wire, and the three phase is supply between any two phases.

3.10.15 MODE ANALYSIS OF Z SOURCE INVERTER The Quasi Z source is same manner as the traditional Z source inverter in which two types of operation take place that is  Shoot Through state  Non Shoot Through state  Which make the system as more efficient in usage. In the Non Shoot Through stage the inverter bridge is depicted from the DC side is equivalent to the current source whereas in traditional voltage source inverter it is forbidden, Because it cause short circuit and prevents the damage of the device. The Quasi Z source inverter has a unique LC and diode network connected to the inverter bridge which modifies the operation of the circuit allowing the Shoot Through stage shown in Fig.4.  This network provides the boost up of the DC link voltage.

Fig.13 Analysis of Z source Inverter

The voltage and current polarities are depicted in the above Fig.4. Assuming, During one switching cycle is T, the interval of shoot through state is T0, non shoot through state is T1 thus the total period is D= T0÷T1. The two capacitor in Z source inverter (ZSI) can be able to sustain the same high voltage, while voltage on the C2 QZSI is lower capacitor ratting. The ZSI has discontinues input current boost mode, while the input current of QZSI is continues due to input inductor L1, which will efficiently reduce the input stress. A Z –source inverter is a type of power inverter a circuit that converts direct current to alternating current. It function as a buck- boost inverter without making use of dc-dc converter bridge due to its unique circuit topology. Impedance (Z) Source networks provide an efficient means of power conversion between source and load in a wide range of electric power conversion applications (dc–dc, dc–ac, ac–dc, ac– ac) The z –source inverter (ZSC) is an alternative power conversion topology that can both buck and boost the input voltage using passive components.it uses unique LC impedance network for coupling the inverter main circuit to the power source, which provides a way of boosting the input voltage ,a condition that cannot be obtained in traditional invertors.it also allows the use of the shoot-through switching state, which avoids the risk of damaging the inverter circuit .

Advantage: The advantages of Z-source inverter are listed as follows, •

The source can be either a voltage source or a current source. The DC source of a ZSI can either be a battery, a diode rectifier or a thyristor converter, a fuel cell stack or a combination of these.

•

The main circuit of a ZSI can either be the traditional VSI or the traditional CSI.

•

Works as a buck-boost inverter.

•

The load of a ZSC can either be inductive or capacitive or another Z-Source network.

Disadvantage: •

Behave in a boost or buck operation only. Thus the obtainable output voltage range is limited, either smaller or greater than the input voltage.

•

Vulnerable to EMI noise and the devices gets damaged in either open or short circuit conditions.

•

The combined system of DC-DC boost converter and the inverter has lower reliability.

•

The main switching device of VSI and CSI are not interchangeable.

3.11.1 MODE analysis of quasi z source network Non-shoot through mode:

Fig:14 Non shoot through mode

In the non-shoot through mode or active mode, the switching pattern for the QZSI is similar to that of Voltage Source Inverter (VSI). The input dc voltage is available as DC link voltage input to the inverter, which makes the QZSI behave similar to a VSI in this mode.

Shoot through mode:

Fig:15 Shoot through mode

In this mode, switches of the same phase in the inverter bridge are switched on simultaneously for a very short duration. The source however isn’t short circuited when attempted to do so because of the presence of LC network (quasi), that boosts the output voltage. The DC link voltage during the shoot through states, is boosted by a boost factor, whose value depends on the shoot through duty ratio for a given modulation index.

3.12 FILTER Filters are essential building blocks in many systems, particularly in communication and instrumentation systems. A filter passes one band of frequencies while rejecting another. Typically implemented in one of three technologies: passive RLC filters, active RC filters and switched capacitor filters. Crystal and SAW filters are normally used at very high frequencies. Passive filters work well at high frequencies, however, at low frequencies the required inductors are larges, bulky and non-ideal. Furthermore, inductors are difficult to fabricate in monolithic from and are incompatible with many modern assembly systems. Active RC filters utilize opamps together with resistors and capacitors and are fabricated using discrete, thick film and thin film technologies. The performance of these filters is limited by the performance of the op-amps (e.g., frequency response, bandwidth, noise, offsets, etc.). Switched-capacitor filters are monolithic

filters which typically offer the best performance in the term of cost. Fabricated using capacitors, switched and op-amps. Generally poorer performance compared to passive LC or active RC filters. The term filter can have a large number of different meanings. In general it can be seen as a way to select certain elements with desired properties from a larger set. Let us focus on the particular field of digital audio effects and consider a signal in the frequency domain. The signal can be seen as a set of partials having different frequencies and amplitudes. The filter will perform a selection of the partials according to the frequencies that we want to reject, retain or emphasize. The filter will modify the amplitude of the partials according to their frequency. Once implemented, it will turn out that this filter is a linear transformation. As an extension, linear transformations can be said to be filters. According to this new definition of a filter, any linear operation could be said to be a filter but this would go far beyond the scope of digital audio effects. It is possible to demonstrate what a filter is by using one’s voice and vocal tract. By doing that we do not modify our vocal cords but we modify the volume and the interconnection pattern of our vocal tract. The vocal cords produce a signal with a fixed harmonic spectrum whereas the cavities act as acoustic filters to enhance some portions of the spectrum. We have described filters in the frequency domain here because it is the usual way to consider them but they also have an effect in the time domain. Filters are generally linear circuits that can be represented as a two-port network:

Filter transfer function is given as, T(jω)=T(s)= V0(s)/Vi(s) A filter shapes the frequency spectrum of the input signal, according to the magnitude of the transfer function. The phase characteristics of the signal are also modified as it passes through the filter. Filters can be classified into a number of categories based on which frequency bands are passes through and which frequency bands are stopped. In circuit theory, a filter is an electrical network that alters the amplitude and or phase characteristics of a signal with respect to frequency. Ideally, a filter will not add new frequencies to the input signal, nor will it change the component frequencies of that signal, but it will change the relative amplitudes of the various frequency components and or their phase relationships.

Filters are often used in electronic systems to emphasize signals in certain frequency ranges and reject signals in other frequency ranges. Such a filter has a gain which is dependent on signal frequency. As an example, consider a situation where a useful signal at frequency f1 has been contaminated with an unwanted signal at f2. If the contaminated signal is passed through a circuit that has very low gain at f2 compared to f1, the undesired signal can be removed, and the useful signal will remain. Note that in the case of this simple example, we are not concerned with the gain of the filter at any frequency other than f1 and f2. As long as f2 is sufficiently attenuated relative to f1, the performance of this filter will be satisfactory. In general, however, a filter’s gain may be specified at several different frequencies, or over a band of frequencies. Since filters are defined by their frequency-domain effects on signals, it makes sense that the most useful analytical and graphical descriptions of filters also fall into the frequency domain. Thus, curves of gain vs frequency and phase vs frequency are commonly used to illustrate filter characteristics, and the most widely-used mathematical tools are based in the frequency domain.

3.12.1 Basic filter types: There are five basic filter types, bandpass, notch, low-pass, high-pass, and all-pass.

• Band Pass: The number of possible bandpass response characteristics is infinite, but they all share the same basic form. Note that while some bandpass responses are very smooth, other have ripple (gain variations in their passbands. Other have ripple in their stopbands as well. The stopband is the range of frequencies over which unwanted signals are attenuated. Bandpass filters have two stopbands, one above and one below the passband.

• Notch or Band-Reject A filter with effectively the opposite function of the bandpass is the band-reject or notch filter. Notch filters are used to remove an unwanted frequency from a signal, while affecting all other frequencies as little as possible. An example of the use of a notch filter is with an audio program that has been contaminated by 60 Hz power-line hum. A notch filter with a centre frequency of 60 Hz can remove the hum while having little effect on the audio signals.

•

Low Pass A third filter type is the low-pass. A low-pass filter passes low frequency signals, and

rejects signals at frequencies above the filter's cut off frequency. Note that the various approximations to the unrealizable ideal low-pass amplitude characteristics take different forms, some being monotonic (always having a negative slope), and others having ripple in the passband and/or stopband. Low-pass filters are used whenever high frequency components must be removed from a signal. An example might be in a light-sensing instrument using a photodiode. If light levels are low, the output of the photodiode could be very small, allowing it to be partially obscured by the noise of the sensor and its amplifier, whose spectrum can extend to very high frequencies. If a low-pass filter is placed at the output of the amplifier, and if its cut off frequency is high enough to allow the desired signal frequencies to pass, the overall noise level can be reduced.

• High Pass High-Pass The opposite of the low-pass is the high-pass filter, which rejects signals below its cut off frequency. High-pass filters are used in applications requiring the rejection of low frequency signals. One such application is in high fidelity loudspeaker systems. Music contains significant energy in the frequency range from around 100 Hz to 2 kHz, but highfrequency drivers (tweeters) can be damaged if low frequency audio signals of sufficient energy appear at their input terminals. A high-pass filter between the broadband audio signal and the tweeter input terminals will prevent low frequency program material from reaching the tweeter. In conjunction with a low-pass filter for the low-frequency driver (and possibly other filters for other drivers), the high-pass filter is part of what is known as a “crossover network”.

• All-Pass or phase shift An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can act as an electrical resonator, an electrical analogue of a tuning fork, storing energy oscillating at the circuit's resonant frequency. The LC circuits are used either for generating signals at a particular frequency, or picking out a signal at a particular frequency from a more complex signal; this function is called a bandpass filter. They are key components in many electronic devices, particularly radio equipment, used in circuits such as oscillators, filters, tuners and frequency mixers.

An LC circuit is an idealized model since it assumes there is no dissipation of energy due to resistance. Any practical implementation of an LC circuit will always include loss resulting from small but non-zero resistance within the components and connecting wires. The purpose of an LC circuit is usually to oscillate with minimal damping, so the resistance is made as low as possible. The fifth and final filter response type has no effect on the amplitude of the signal at different frequencies. Instead, its function is to change the phase of the signal without affecting its amplitude. This type of filter is called an all-pass or phase shift filter. All-pass filters are typically used to introduce phase shifts into signals in order to cancel or partially cancel any unwanted phase shifts previously imposed upon the signals by other circuitry or transmission media. The phase shift here is equal to θ radians. The relation between time delay and phase shift is TD = θ/2πω, so if phase shift is constant with frequency, time delay will decrease as frequency increases.

3.12.2 High Pass filter The signal component of the high frequency cannot easily pass although the signal component of the low frequency area can pass because the impedance of L rises in the area where the frequency is high, simultaneously the impedance of C lowers.

Fig: 16 High pass filter circuit

3.12.3 Low Pass Filter The signal component of the low frequency cannot easily pass although the signal component of the high frequency area can pass because the impedance of L falls simultaneously as the impedance of C rises in the area where the frequency is low.

Fig: 17 Low pass filter circuit

3.12.4 Band Pass Filter The LC circuit connected in series can pass through only signal component of the resonance frequency vicinity. Further, the LC circuit connected in parallel becomes the resonance frequency vicinity, then it loses the function to let bypass the signal component to the ground. Therefore, it becomes possible to pass only the signal component of the band with the resonance frequency vicinity.

Fig:19 Band pass filter circuit

The two-element LC circuit described above is the simplest type of inductor-capacitor network (or LC network). It is also referred to as a second order LC circuit to distinguish it from more complicated (higher order) LC networks with more inductors and capacitors. Such LC networks with more than two reactance may have more than one resonant frequency.

OPERATION An LC circuit, oscillating at its natural resonant frequency, can store electrical energy. See the animation at right. A capacitor stores energy in the electric field (E) between its plates, depending on the voltage across it, and an inductor stores energy in its magnetic field (B), depending on the current through it. If an inductor is connected across a charged capacitor, current will start to flow through the inductor, building up a magnetic field around it and reducing the voltage on the capacitor. Eventually all the charge on the capacitor will be gone and the voltage across it will reach zero. However, the current will continue, because inductors resist changes in current. The current will begin to charge the capacitor with a voltage of opposite polarity to its original charge. Due to Faraday's law, the EMF which drives the current is caused by a decrease in the magnetic field, thus the energy required to charge the capacitor is extracted from the magnetic field. When the magnetic field is completely dissipated the current will stop and the charge will again be stored in the capacitor, with the opposite polarity as before. Then the cycle will begin again, with the current flowing in the opposite direction through the inductor. The charge flows back and forth between the plates of the capacitor, through the inductor. The energy oscillates back and forth between the capacitor and the inductor until (if not replenished from an external circuit) internal resistance makes the oscillations die out. In most applications the tuned circuit is part of a larger circuit which applies alternating current to it, driving continuous oscillations. If the frequency of the applied current is the circuit's natural resonant frequency (natural frequency f0 below), resonance occur. The tuned circuit's action, known mathematically as a harmonic oscillator, is similar to a pendulum swinging back and forth, or water sloshing back and forth in a tank; for this reason the circuit is also called a tank circuit. The natural frequency (that is, the frequency at which it will oscillate when isolated from any other system, as described above) is determined by the capacitance and inductance values. In typical tuned circuits in electronic equipment the oscillations are very fast, from thousands to billions of times per second.

RESONANCE EFFECT Resonance occurs when an LC circuit is driven from an external source at an angular frequency ω0 at which the inductive and capacitive reactances are equal in magnitude. The

frequency at which this equality holds for the particular circuit is called the resonant frequency. The resonant frequency of the LC circuit is

𝜔0=1/√𝐿𝐶 where L is the inductance in henrys, and C is the capacitance in farads. The angular frequencyω0 has units of radians per second. The equivalent frequency in units of hertz is 𝜔0 =1/√𝐿𝐶 𝑓0 = 𝜔0\2π=1/2 π√𝐿𝐶

LC circuits are often used as filters; the L/C ratio is one of the factors that determines their "Q" and so selectivity. For a series resonant circuit with a given resistance, the higher the inductance and the lower the capacitance, the narrower the filter bandwidth. For a parallel resonant circuit the opposite applies. Positive feedback around the tuned circuit ("regeneration") can also increase selectivity (see Q multiplier and Regenerative circuit). Stagger tuning can provide an acceptably wide audio bandwidth, yet good selectivity.

3.13 INDUCTION MOTOR The induction motor was the last great invention in electric motors before the age of silicon and semiconductors that gave us the brushless DC motor. In induction motor is in some sense the simplest motor of all. The drive current is passed through coils on the stator, just as in the synchronous AC motor. But in an induction motor, the rotor holds nothing except for some windings of wire. The drive current in the stator induces a magnetic field in the stator, and the stator field in turn induces one in the rotor wires, and the two fields interact to allow the rotor to be pushed around and electively convert electrical energy to mechanical energy. Of all the motor types, the induction motor can seem the most mysterious or even impossible because it seems like it creates motion out of nothing, as though it were driving itself. Really, however, it is not very different from the other types. All work by the interaction of magnetic

fields in stator and rotor. In the induction motor case, the production of one of those magnetic fields is just very indirect. But if designed right, this induction works very well, and the resulting motor is about as simple as possible. Its ruggedness and simplicity means that it is the dominant electric motor type for industrial use. Induction motors do differ in behaviour from synchronous motors in two important ways. First, they do not rotate at exactly the same frequency as that of the alternating drive current. Instead there is some “slip” - the rotor turns slightly slower than the AC current frequency. Second, the torque of the induction motor is actually proportional to that slip. This means that torque is not zero at no zero speed, but is actually maximum, because the slip is maximum: 60 Hz minus zero

CHAPTER 4 DESIGN CALCULATION 4.1 Design Of Solar Panel SOLAR PANEL DESIGN STEP 1: The following parameters were considered while designing the solar panel •

Type of load, dc or ac

•

Number of loads

•

Power, voltage and current ratings of each load

•

Hours of load operation per day

•

Energy required per day by the load

•

Efficiency of the power converter circuit

Energy consumed by the load is obtained by multiplying its power ratting by the number of hours of operation. CONDITION TO BE NOTED There is lot of variation in daily energy requirement from season to season, the peak consumption may occur in winter or in summer, depending of geographical location of the system. For an industry, the peak energy consumption are determined by other parameter such as work load

, production rate etc.

Step 2: DETERMINATION OF INVERTER RATING The required load energy is supplied from the battery bank through an inverter (DC TO AC) in case of AC loads. At the output invertor should able to handle the current required by the load similarly the Input end of the inverter should be able to handle the current taken from the battery. Thus in both the case the input and output must be specified, the input can be in the range of 12v to 72v,and output can be Sin the range of 220v ,60Hz.

DAILY ENERGY SUPPLIED TO INVERTER The daily energy used by the inverter is 720Wh.the energy supplied by the battery through invertor. The conversion process in the invertor has its own efficiency. Good invertor provides efficiency of 97% here we take it as 93%. 720/0.93 = 774.193Wh/day.

Deciding the system voltage To generate enough voltage to charge series connected batteries of 24 v terminal voltage. Therefore one needs to optimise between the power loss and system voltage.

Sizing of batteries The parameters to be considered regarding batteries are as follows: •

Depth of discharge(DoD) of battery

•

Voltage and ampere-hour(Ah) capacity of battery

•

Number of days of autonomy

Determination of battery capacity for the given load: In the solar PV panel normally the deep discharge batteries are used with DoD in the range of 60% to 80%.we consider that batteries of 12 V, 100Ah. Out of 100Ah capacity only 100*0.7 =70Ah is usable capacity. The energy need to supplied by the battery is 774.193Wh/day. 774/24 = 32.258Ah The number of battery required 32.258/70 = 0.4608. Two 12v battery should be connected in series to get 24V terminal voltage. Considering of the battery autonomy: More batteries would be required if we have to design the PV system for some autonomy during the completely cloudy condition. The autonomy is defined as the number of days the battery should be able to supply the energy to the load even when for those number of days there is no sunshine. Thus, 2 days autonomy means the battery bank should be able to supply the energy to the load where there is no sunshine for 2 days. Thus depending on the number charge that needs to be supplied by the battery bank

If total daily Ah requirement is X and the number of days of autonomy is days, the totally Ah required autonomy (X+n*X)= 21.50+2*21.50 = 64.5Ah.

4.1.2 Sizing of PV modules To design the capacity and the number of PV modules. In this regard the parameters of concern for PV module sizing are: •

Voltage, current and wattage of the module

•

Solar radiation at a given time and at given location

•

Efficiency of battery

•

Temperature of the module

•

Efficiency of the MPPT and charge controller unit

•

Dust level in working environment

4.1.3 Daily energy generated by PV panels The PV panels are required to supply energy to the battery which is consumed daily but not the total energy stored in a battery bank. The energy taken out from the battery bank is the energy required by the load on daily basis. In case when a battery bank is designed for certain autonomy, The total energy stored in battery is much more than the daily energy consumed by the load. The extra energy stored in battery bank is only to supply the load during cloudy days. The daily energy supplied by the battery bank is 774.193Wh The energy to the input terminal of the battery bank is supplied through controller electronics . the efficiency of the controller is generally high ,we consider 90%. 774.193/0.90 = 860.214Wh Thus 860Wh energy should be generated by PV panels everyday .from the design point of view , the controller circuit should be able to handle the current flowing from the PV modules at its input and from controller circuit should be same as system voltage ,in case of 24V.

4.1.4 Solar radiation, capacity and number of panels: In order to charge batteries, the PV panels need to supply the energy to the battery bank at 24V.therefore, total Ah generated by the PV panels should be 860.214/24 = 35.842Ah

The other factors the degrade the solar cell performance can be taken in account. For high module operating temperature, dust settlement on PV modules, etc. All the parameters would increase the amount of Ah produced by the PV modules. The solar PV modules power capacity is measured at an input solar radiation of 1000W/m2. During a day, from sunrise to sunset, the solar radiation intensities varies significantly. Number of daily sunshine hours is equivalent to 1000W/m2 are esteemed for the location at which PV systems needs to be installed. In India, the peak equivalent sunshine hours varies between 5 hours to 7 hours, corresponding to 5000Wh/m2 to 7000Wh/m2 . We consider the location of the solar panel with the peak of 6 hours equivalent to peak sunshine hours. 35.842/6 = 5.973A One module can provide 5A current, we require 5.973/5 = 1.1946A we need 2 PV modules, the terminal voltage must be 24V therefore the modules must be connected in series to get higher voltage as possible. Thus the above design completes the PV system design, we have identified all the components capacity and the number to be used in the PV system to supply the daily energy 720W/h to the load given.

4.2 DESIGN OF QUASI NETWORK 4.2.1 Inductor Design: During non shoot through mode capacitor voltage is always equal to input whereas voltage across inductor is zero. During shoot through mode there is linear increase in current across inductor and voltage across inductor and capacitor is equal. Average current through inductor is given by, IL=P/Vdc

Where P is total power Vdc is input voltage Maximum current flows through inductor only when maximum shoot through happens that results in maximum ripple current. Average capacitor voltage is given by Vc=(1-T0/T)*Vdc/(1-2T0/T) L1=L2=(0.1*10*300/10.67)=3mH

4.2.2 Design of capacitor Capacitor absorbs voltage ripple and maintains constant voltage. In shoot through state capacitor charges inductor and current through inductor and capacitor is equal. VC= (IL(avg) TS)*(1/C) Capacitor voltage ripple is 0.17%. C=6.67*0.1*10(300*0.0017) =3.401 Therefore quasi network consists of inductance and capacitance values as 3mH and 1000µF.

4.3 DESIGN OF LC CIRCUIT XL= -XC 1 𝜔𝐿= 𝜔𝐶 Solving for ω we have

Converting angular frequency (in radians per second) into frequency (in hertz),

CHAPTER 5

SIMULATION 5.1 MATLAB The MATLAB helps to learn quickly, the name stands for Matrix Laboratory. Simulink, developed by Math Works, is a graphical programming environment for modelling, simulating and analysing multi domain dynamical systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries. It offers tight integration with the rest of the MATLAB environment and can either drive MATLAB or be scripted from it. Simulink is widely used in automatic control and digital signal processing for multi domain simulation and Model-Based Design. MATLAB R2014b version is used here for advanced tools and operations. Math Works and other third-party hardware and software products can be used with Simulink. Simulink can automatically generate C source code for real-time implementation of systems. As the efficiency and flexibility of the code improves, this is becoming more widely adopted for production systems. In addition to being a tool for embedded system design work because of its flexibility and capacity for quick iteration Embedded Coder creates code efficient enough for use in embedded systems. •

MATLAB toolbox packaging as single, installable files for easy sharing and downloading of custom toolboxes

•

Date and time data types with time zone and display options

•

Arduino and Android hardware support for interacting with motors and actuators, and for accessing sensor data

Statistics Tool box Multiclass machine-learning framework for binary classifiers such as SVM, and for generalized linear mixed-effects (GLME) models. Image processing Tool box: image segmentation app, region analysis app, and C code generation for 19 functions with MATLAB Coder

5.1.1 SIMULINK •

Smart editing cues for accelerated model building, and editor views for annotations and interfaces

•

Fast simulation restart for running consecutive simulations quickly

•

Simulink Functions for creating and calling reusable functions from anywhere in Simulink and State-flow

•

Live streaming and data cursors in Simulation Data Inspector Sim-scape

•

Domain-specific line styles for representing physical connections State-flow

•

Faster debugging with conditional breakpoints, watch data, and fast animation mode MATLAB Report Generator and Simulink Report Generator

•

Fill-in-the-blanks Word and HTML forms for enhanced custom reports

5.2 SIMULATION RESULTS SIMULINK model has been built in MATLAB for PV generation system for analysis and parameters for simulation are shown in I. Table. The SIMULINK model of quasi z source inverter with PV array fetched network along with inverter and filter circuit are shown.

Design Parameter of Proposed System PARAMETER

VALUE

UNIT

Input Voltage

25

V

3

mH

1000

µF

LC Filter

0.06

& H

(LF& CF)

90

(Vin) Inductor (L1) Capacitor(C2)

&µF

Fig: 19 Tabulation of design parameters

SIMULINK model has been built in MATLAB for PV generation system for analysis and parameters for simulation are as follows

L1=L2= 3mH

C1=C2=1000μF

LF=0.06H

CF=90μF

Output is 50HZ,220V and output power is 180W approximately.

Fig.20 Simulation for the Proposed system

time Fig 21 Output waveform of Quasi network

time Fig.22 Output Voltage of Proposed System

The above Fig.22 shows the Output Voltage waveform. In this waveform the maximum voltage attains 80V.

CHAPTER 6 HARDWARE DETAILS

6.1 DESCRIPTION OF HARDWARE DETAILS 6.1.1 ARDUINO The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.0) or ATmega168 (Arduino Nano 2.x). It has more or less the same functionality of the Arduino, but in a different package. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one.

Fig:23 Arduino Pin details

SPECIFICATION Microcontroller -Atmel ATmega168 or ATmega328 Operating Voltage (logic level) -5 V Input Voltage (recommended)-7-12 V Input Voltage (limits)-6-20 V Digital I/O Pins-14 (of which 6 provide PWM output) Analog Input Pins-8 DC Current per I/O Pin-40 mA Flash Memory-16 KB (ATmega168) or 32 KB (ATmega328) of which 2 KB used by bootloader SRAM-1 KB (ATmega168) or 2 KB (ATmega328) EEPROM 512 bytes (ATmega168) or 1 KB (ATmega328) Clock Speed-16 MHz Dimensions-0.73" x 1.70"

POWER The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source. The FTDI FT232RL chip on the Nano is only powered if the board is being powered over USB. As a result, when running on external (non-USB) power, the 3.3V output (which is supplied by the FTDI chip) is not available and the RX and TX LEDs will flicker if digital pins 0 or 1 are high.

Memory The ATmega168 has 16 KB of flash memory for storing code (of which 2 KB is used for the bootloader); the ATmega328 has 32 KB, (also with 2 KB used for the bootloader). The ATmega168 has 1 KB of SRAM and 512 bytes of EEPROM (which can be read and written with the EEPROM library); the ATmega328 has 2 KB of SRAM and 1 KB of EEPROM.

6.2 MOSFET The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal-insulator-semiconductor field-effect transistor or MISFET is a term almost synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect transistor. The main advantage of a MOSFET is that it requires almost no input current to control the load current, when compared with bipolar transistors. In an enhancement mode MOSFET, voltage applied to the gate terminal increases the conductivity of the device. In depletion mode of transistors, voltage applied at the gate reduces the conductivity. The "metal" in the name MOSFET is now often a misnomer because the gate material is often a layer of polysilicon (polycrystalline silicon). Similarly, "oxide" in the name can also be a misnomer, as different dielectric materials are used with the aim of obtaining strong channels with smaller applied voltages. The MOSFET is by far the most common transistor in digital circuits, as hundreds of thousands or millions of them may be included in a memory chip or microprocessor. Since MOSFETs can be made with either p-type or n-type semiconductors, complementary pairs of MOS transistors can be used to make switching circuits with very low power consumption, in the form of CMOS logic.

6.2.1 IRF740 POWER MOSFET:

Fig:24 Pin diagram of IRF740

FEATURES • Dynamic dV/dt Rating • Repetitive Avalanche Rated

• Fast Switching • Ease of Paralleling • Simple Drive Requirements • Compliant to RoHS Directive 2002/95/EC

DESCRIPTION Third generation Power MOSFETs from Vishay provide the designer with the best combination of fast switching, ruggedized device design, low on-resistance and cost effectiveness. The TO-220AB package is universally preferred for all commercial-industrial applications at power dissipation levels to approximately 50 W. The low thermal resistance and low package cost of the TO-220AB contribute to its wide acceptance throughout the industry.

PRODUCT SUMMARY VDS (V) 400 RDS(on) (Ω)

VGS = 10 V/0.55

Qg (Max.) (nC) 63 Qgs (nC) 9.0 Qgd (nC) 32 Configuration Single

Switching time test circuit

Fig:25 Switching time test circuit

6.3 Optocoupler In electronics, an opto-isolator, also called an optocoupler, photo coupler, or optical isolator, is a component that transfers electrical signals between two isolated circuits, Optoisolators prevent high voltages from affecting the system receiving the signal. Commercially available opto-isolators withstand input-to-output voltages up to 10 kV and voltage transients with speeds up to 25 kV/μs. A common type of opto-isolator consists of an LED and a phototransistor in the same opaque package. Other types of source-sensor combinations include LED-photodiode, LEDLASCR, and lamp-photo resistor pairs. Usually opto-isolators transfer digital (on-off) signals, but some techniques allow them to be used with analog signals. An opto-isolator contains a source (emitter) of light, almost always a near infrared light emitting diode (LED), that converts electrical input signal into light, a closed optical channel (also called dielectrical channel]), and a photo sensor, which detects incoming light and either generates electric energy directly, or modulates electric current flowing from an external power supply. The sensor can be a photo resistor, a photodiode, a phototransistor, a silicon-controlled rectifier (SCR) or TRIAC. Because LEDs can sense light in addition to emitting it, construction of symmetrical, bidirectional opto-isolators is possible. An opto-coupled solid-state relay contains a photodiode opto-isolator which drives a power switch, usually a complementary pair of MOSFETs. A slotted optical switch contains a source of light and a sensor, but its optical channel is open, allowing modulation of light by external objects obstructing the path of light or reflecting light into the sensor.

Fig:26 Pin diagram of optocoupler FEATURES Current transfer ratio, 50 % typical Leakage current, 1.0 nA typical

Compliant to RoHS Directive and in accordance to WEEE 2002/96/EC

DESCRIPTION The MCT6 is a two channel optocoupler for high density application. Each channel consisits of an optically coupled pair with a gallium arsenide infrared LED and a silicon NPN phototransistor signal information including a dc level can be transmitted by device while maintaining a high degree of electrical isolation between input and output. The MCT6 is especially designed for driving medium speed logic, where it may be used to eliminate troublesome ground loop and noise problems. It can also be used to replace relays and transformers in many digital interface applications as well as analog applications such as CRT modulation.

SWITCHING SCHEMATIC

V CC = 5 V

IF = 10 mA VO f = 10 kHz, DF = 50 %

R L = 100 Ω

Fig:27 Switching circuit of optocoupler

6.4 HARDWARE SETUP

Fig:28 circuit connections of proposed system

6.4.1 HARDWARE RESULTS Output of Quasi Z source Network

INPUT VOLTAGE

BOOSTED OUTPUT VOLTAGE

5.1

10

10.7

22

20.3

43

30.1

53

Fig:29 Tabulation of input and quasi network output voltage

Pulse Generation Output:

Fig:30 pulse generation output

OUPUT Voltage Waveform:

Fig:31 Output voltage waveform

CONCLUSION This project is to develop quasi Z source inverter which increases output voltage level by using quasi Z source network with reduced switching losses and high reliability. The new quasi-z-source inverter, is a modified inverter which is derived from the normal z source inverter, this quasi z source inverter is a DC to AC inverter which is the traditional form of buck and boost inverter. Quasi network is mainly used to boost the low input voltage to high output voltage, thereby it provides continuous current from solar panel with reduced component rating and boosted output voltage is given to inverter and output level is increased. We have simulated quasi z source inverter for single phase employing solar panel. The output voltage and voltage across quasi network is observed. We have implemented design using MATLAB R2014b software. With MATLAB simulation output is produced approximately 80V. The PV generation system is one of promising technique as it increases efficiency of proposed topology as it does single stage of boost and dc to ac inversion. We have implemented the hardware for single quasi z source inverter employing solar panel using ARDUINO and output voltage is verified. .

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