Design and Construction of Microcontroller Based Smart Solar Charge Controller with Automatic Brightness Controlling of Solar Based LED Street Light (original) (raw)
Design and Construction of Microcontroller Based Smart Solar Charge Controller for Automatically Controlling Solar Based LED Street Light
UNIVERSITY OF DHAKA
Department of Electrical and Electronic Engineering
SUMMITTED BY
- Exam Roll: 1229
Registration No:2011-213-820
Session: 2011-12
2. Exam Roll: 1248
Registration No:2011-513-782
Session: 2011-12
CERTIFICATE OF APPROVAL
This is to certify that the project entitled Design and Construction of Microcontroller Based Smart Solar Charge Controller for Automatically Controlling Solar Based LED Street Light has been successfully completed under the guidance of Dr. Md. Habibur Rahman in recognition to the fulfillment of the degree of B.Sc. in Electrical and Electronic Engineering at University of Dhaka.
Project advisor
Dr. Md. Habibur Rahman
Professor, Department of Electrical and Electronic Engineering, University of Dhaka
DECLARATION
We hereby declare that this project report was written based only on the works and results found by us. Materials from the articles, works, thesis or researches of other researchers have been mentioned by their references. This report, neither in whole nor in part, has been previously submitted for any degree.
ACKNOWLEDMENIS
First, we would like to thank our department for giving us this chance to do this project. Secondly we are very much thankful to our honorable project coordinator Dr. Md. Habibur Rahman, professor, department of Electrical and Electronic Engineering, University of Dhaka for guiding us through our project work. We would also like to thank him for giving us appropriate advice regarding system devices, system designing and circuit works and in documentation of every single detail. Whenever we required his excellence he was always there for us with his brilliant ideas. Thirdly, we want to express our special regards to all the teachers who taught us in those four years with all the theory courses. Those courses enhanced the level of our knowledge and helped us to complete this project successfully.
We would like to extend our thanks to the laboratory staffs for their fast response and cooperation with us to get all the materials we need for our case.
ABSTRACT
Bangladesh being an over-populated country needs to produce huge amount of energy to meet its people’s demands. On the other hand it is quiet impossible for her to provide them with sufficient energy with the conventional way of producing energy due to her being a developing third world country. Only 62%62 \% of her people have the privilege of using electricity. So apart from finding cost effective ways to harness energy we should also look forward to using the produced energy efficiently. In this project we look to find a way to reduce the pressure on grid energy by empowering the street lights using solar panels. In this regard we also focus on having a smart solar charge controller circuit for ensuring battery longevity. In this project PIC16F876A microcontroller has been used to sense different voltages and make some decision according to them. The CCP module of the microcontroller has been used for a variable duty cycle PWM signal to adjust the brightness of the LED street lights. By the use of LED street lights the reduction of the consumption of energy was ensured. Apart from this, it can also be used for the electrification of remote places using solar energy as the smart solar charge controller is cost effective and easy to implement.
TABLE OF CONTENTS
TOPIC: PAGE
Certificate of approval … 2
Declaration … 3
Acknowledgements … 4
Abstract … 5
List of figures … 8
List of tables … 11
CHAPTER 1: INTRODUCTION … 12
1.1 Overview … 12
1.2 Objectives of the project … 13
1.3 Aim of the project … 13
1.4 Project outline … 13
CHAPTER 2: THEORITICAL ANALYSIS … 15
2.1 Solar photovoltaic panel and solar radiation … 15
2.1.1 Solar energy … 15
2.1.2 Solar cell, solar panel, solar array … 16
2.1.3 Working principle of a PV cell … 17
2.1.4 PV system and its working … 18
2.1.5 Why PV system require battery? … 19
2.2 Basics of charge controller … 20
2.2.1 Functions of charge controller … 20
2.2.2 Charge controller design … 22
2.2.3 Charge controller set points … 25
2.2.4 Multi stage charge controller … 28
2.3 Microcontroller … 29
2.3.1 Basic structure of a Microcontroller … 30
2.3.2 Advantages of using a Microcontroller … 32
2.3.3 Types of Microcontroller … 33
2.3.4 Why PIC Microcontroller … 37
2.3.5 Criteria for choosing Microcontroller … 38
2.4 Lead acid battery … 39
2.4.1 Battery construction … 39
2.4.2 Battery types … 41
2.4.3 Charging of lead acid battery … 42
2.4.4 Advantages and limitations … 43
CHAPTER 3: PROJECT DESIGN … 45
3.1 System equipments … 45
3.2 Voltage sensing circuit … 59
3.3 Light intensity sensing circuit … 60
3.4 Switching section … 61
3.5 Control section and Pulse width modulation … 62
3.6 System modeling … 64
3.7 Programming PIC Microcontroller … 68
3.8 Algorithm and flowchart … 69
3.9 Program code … 71
CHAPTER 4: SIMULATION & EXPERIMENTAL RESULTS … 74
4.1 Schematic circuit … 74
4.2 Simulation result … 74
4.3 Experimental results … 83
CHAPTER 5: CONCLUSION AND FUTURE SCOPES … 87
REFERENCE
LIST OF FIGURES
| Figure no | Title | Page |
|---|---|---|
| Figure 2.1.1 | Average solar radiation on earth’s surface | 16 |
| Figure 2.1.2 | Solar cell, solar panel, solar array | 17 |
| Figure 2.1.3 | Working principle of a PV cell | 17 |
| Figure 2.1.4 | Major Components of a PV system | 19 |
| Figure 2.1.5 | Block diagram representation of how a PV system works | 19 |
| Figure 2.2.1 | Overcharge protection by charge controller | 21 |
| Figure 2.2.2 | Over-discharge protection by charge controller | 22 |
| Figure 2.2.3 | Self regulation of charge controller | 23 |
| Figure 2.2.4 | Shunt regulation for charge controller | 24 |
| Figure 2.2.5 | Series regulation for charge controller | 25 |
| Figure 2.2.6 | Charge controller set points | 26 |
| Figure 2.2.7 | Three stage of charging | 29 |
| Figure 2.3.1 | Fundamental components of a microcontroller | 30 |
| Figure 2.3.2 | Basic structure of a microcontroller | 32 |
| Figure 2.3.3 | 8051 microcontroller architecture | 33 |
| Figure 2.3.4 | A PIC microcontroller IC and its architecture | 34 |
| Figure 2.3.5 | AVR microcontroller and its architecture | 35 |
| Figure 2.3.6 | An ARM microcontroller IC and its architecture | 36 |
| Figure 2.3.7 | Different types of microcontrollers | 36 |
| Figure 2.4.1 | Single cell of lead acid battery | 40 |
| Figure 2.4.2 | 12V lead acid battery | 40 |
| Figure 2.4.3 | Charge stages of lead acid battery | 43 |
| Figure 3.1.1 | Pin diagram of PIC16f876A | 45 |
| Figure 3.1.2 | A solar panel | 46 |
| Figure 3.1.3 | LDR used in this project and its circuit symbol | 47 |
| Figure 3.1.4 | LDR resistance vs light intensity graph | 48 |
| Figure 3.1.5 | 12V Lead acid battery | 48 |
|---|---|---|
| Figure 3.1.6 | 7805 ic and its pin diagram of 7805 ic | 49 |
| Figure 3.1.7 | Relay and its symbol | 50 |
| Figure 3.1.8 | Circuit symbols of different relays | 51 |
| Figure 3.1.9 | Symbol and structure of power MOSFET | 53 |
| Figure 3.1.10 | IRFP250N MOSFET and its symbol | 53 |
| Figure 3.1.11 | 4N25 ic | 55 |
| Figure 3.1.12 | Phototransistor | 55 |
| Figure 3.1.13 | C828 ic | 56 |
| Figure 3.1.14 | Resistor, diode and capacitor | 57 |
| Figure 3.1.15 | Light emitting diode | 58 |
| Figure 3.1.16 | LED light bulb | 58 |
| Figure 3.1.17 | Functional block diagram | 59 |
| Figure 3.2.1 | Battery voltage sensing circuit | 60 |
| Figure 3.3.1 | Light intensity sensing circuit | 61 |
| Figure 3.4.1 | Switching by using relay | 62 |
| Figure 3.5.1 | 50%, 75%, and 25% Duty Cycle | 63 |
| Figure 3.5.2 | Conceptual block diagram of the project | 64 |
| Figure 3.6.1 | Circuit diagram of this project | 66 |
| Figure 3.9.1 | Screen shots of Program Code | 73 |
| Figure 4.4.1 | Schematic circuit of the design | 74 |
| Figure 4.2.1 | Battery fully charged, light intensity is low and PWM is showing 100%100 \% duty cycle | 76 |
| Figure 4.2.2 | Battery is fully charged, light intensity is moderate and PWM has 50%50 \% duty cycle | 78 |
| Figure 4.2.3 | Battery fully charged, light intensity is fare and PWM shows 0%0 \% duty cycle | 80 |
| Figure 4.2.4 | Battery in is charging state and load is connected | 81 |
| Figure 4.2.5 | Battery level critically low( dead battery), load is disconnected. | 83 |
|---|---|---|
| Figure 4.3.1 | Overall hardware circuit of the project | 84 |
| Figure 4.3.2 | Battery in charging state and load in ON state ( 100%100 \% duty ratio) | 84 |
| Figure 4.3.3 | Battery in charging state and load in ON state ( 50%50 \% duty ratio) | 85 |
| Figure 4.3.4 | Battery in charging state and load in OFF state (0% duty ratio) | 85 |
| Figure 4.3.5 | Battery in discharging state and load in ON state | 86 |
LIST OF TABLES
| Table no | Title | Page |
|---|---|---|
| Table 3.1 | Pin description of 7805 ic | 49 |
| Table 3.2 | Name of each pin of 4N25 | 55 |
| Table 3.3 | Total component list | 59 |
CHAPTER I:INTRODUCTION
1.1 OVERVIEW:
Bangladesh is a small country with a large population. Being a developing country the need for energy in Bangladesh is huge. The amount of electrical energy (7000-8000MW) produced each year in Bangladesh is not enough. Only 62%62 \% of her people have the luxury of using electricity. So in a country like Bangladesh we need to look for other resources of energy. Among them solar energy is the most popular form of renewable energy we can concentrate on. The other thing we need to keep in mind that we should think on how to use the produced energy more efficiently. By ensuring efficient use of produced electricity we can overcome the scarcity of energy to a great extant.
In our country we use a good amount of electrical energy to light up the streets of the town and cities and also in highways at night. This project shows an alternative energy source for lighting the streets at night. Here we focus on solar energy to be used for street lights. The conventional sodium lights should be replaced by LED lights because they (LED lights) are more energy efficient. And for the controlling purpose we look forward to using microcontrollers.
In this project we want to have an automatic system capable of smart charging of a rechargeable battery at day using a solar module. This battery later can be used as the energy source for the LED street lights at night. Here we would use an LDR (light dependent resistor) to sense the light intensity of the outside environment. The microcontroller’s analog channels will sense the voltage from LDR and according to that it will generate a PWM signal with variable duty cycle depending on outside light intensity. This variable PWM signal will be later used to control the brightness of LED lights. After having such a system we can not only light the streets of towns and cities but also in the remote mountainous, urban areas where electricity cannot be reached. Apart from that if this project idea is implemented in practical life then it will reduce an enormous
pressure on grid energy which is now being used in street lights of Bangladesh. And this unused grid energy can be used in other productive works.
1.2 OBJECTIVES OF THE PROJECT:
=>To design a smart solar charge controller circuit
=>To design an automatic LED brightness controlling circuit according to the light intensity of the outside atmosphere
=> Implement these designs in simulation software
=>Test the simulation results
=>Construct the above two circuits using a microcontroller on a bread board
=>Test for its functionality
1.3 AIM OF THE PROJECT:
The project we mainly focus on four aspects. Firstly we are looking to build a PV system with automatic brightness control of LED street light circuit using a microcontroller with a view to reducing the dependency of street lights on national grid electrical energy. Secondly, we are focusing on smart charging of the battery which will eventually become the source for the LED street lights to ensure its longevity. Thirdly, we are concentrating on electrification of rural areas such as mountains, urban areas or some remote places or islands. Fourthly, we emphasis on implementing the system in a cost effective way and also regarding its energy efficiency.
1.4 PROJECT OUTLINE:
The project of designing and construction of Microcontroller based smart solar charge controller with automatic brightness control of LED street light is divided into five chapters-
Chapter1: An overview of the project. The motivation and aim of the project is mentioned in this chapter. The objectives of this project are described in short.
Chapter2: In this chapter all the necessary theories regarding this project is discussed. The definitions of solar cell, PV systems and its working principle, microcontroller and its basic features along with the basics of charge controller and battery is described here.
Chapter3: In this chapter, overall design of the project is described in brief. The voltage sensing of battery, the intensity sensing circuit of outside light, the system modeling, programming PIC microcontroller, program code, algorithm and flowchart of this project are documented here.
Chapter4: chapter 4 describes the result parts; simulation circuits, experimental results, schematic circuit etc.
Chapter5: chapter 5 discusses about the future scopes of the projects along with its possibility of practical implementation. Then the conclusion is drawn.