110V UNIVERSAL BATTERY CHARGING PANEL 
USING PIC MICROCONTROLLER 
A dissertation submitted to the 
Department of Electrical Engineering, University of Moratuwa 
in partial fulfillment of the requirements for the 
degree of Master of Science 
by 
SWARNA KUMARA VIJITHANANDA 
Supervised by: Dr. J.P Karunadasa 
Department of Electrical Engineering 
University of Moratuwa, Sri Lanka 
December 2006 
DECLARATION 
The work submitted in this dissertation is the result of my own 
investigation, except where otherwise stated. 
It has not already been accepted for any degree, and is also not being 
concurrently submitted for any other degree. 
S.K Vijithananda 
Date: \ \ CM 
We/I endorse the declaration by the candidate. 
CONTENTS 
Declaration I 
Abstract IV 
Acknowledgement VI 
List of Figures VII 
List of Tables IX 
CHAPTER 1 
1.00 Introduction 1 
1.10 Requirement of the Project 1 
1.20 Project Benefits 1 
1.30 Technical Concept & Techniques 2 
1.40 Project Tools & Materials 2 
CHAPTER 2 
2.00 Structure of the Project 12 
2.10 Hardware Circuitry 13 
2.11 Design of DC-DC Converter 15 
2.12 Testing Circuit with 555 Timer 21 
2.13 Converter Switching Amplifier Circuits 26 
2.14 Overcurrent & Over/Under Voltage Circuits 30 
2.20 Software Programming 34 
2.21 Introduction to PIC (16F876A) Microcontroller 34 
2.22 Analog to Digital Converter (A/D) Module 37 
2.23 Operation in PWM Mode 45 
2.24 Assembly Programs for A/D Conversion 49 
& PWM operation 
2.24 (i) A/D Conversion 49 
2.24 (ii) PWM Operation 49 
II 
CHAPTER 3 
3.00 Results and Practical Observation 55 
3.10 Waveforms of the DC-DC Converter 55 
3.20 Voltage variation of the Panel Output 60 
3.30 Project Photos 64 
CHAPTER 4 
4.00 Practical Limitations Challenges & Difficulties 69 
4.10 Technical limitations & Challenges 69 
4.20 Financial Difficulties 69 
CHAPTER 5 
5.00 Conclusion 71 
5.10 Conclusion and Remarks 71 
5.20 Recommendation for Future Developments 71 
References 73 
Appendix A Definitions of the terms 74 
Appendix B Program Codes 77 
III 
Abstract 
Conventional power electronics and electronic control circuits have been replacing by the 
intervention of the microprocessors/microcontrollers in modern industrial applications. 
This is mainly because with their applications the whole systems becomes more and more 
compact while enhancing the durability. On the other even with the more robust 
applications hand more accurate & fine operation could achieve by using such modern 
programming devices. 
This project was origin from based on an actual requirement of designing 1 lOv battery 
charging panel (to energize the batteries in spring charge type breakers)for electrical 
engineering division of Jaya Container Terminal(J.C.T) of Sri Lanka Ports Authority. But 
this technique would use to not only to charge batteries of spring charge breakers , but 
also batteries widely use in VHF communication hand held sets, explosive detectors, 
emergency lamps, etc... 
Rechargeable batteries are vital to portable electronic equipment such as laptop 
computers and cell phones. Fast charging circuits must be carefully designed and 
are highly dependent on the particular battery's chemistry. The most popular types 
of rechargeable batteries in use today are the Sealed-Lead-Acid (SLA), Nickel-
Cadmium (NiCd), Nickel-Metal-Hydride (NiMH), and Lithium-Ion (Li-Ion). Li-Ion is 
fast becoming the chemistry of choice for many portable applications because it 
offers a high capacity-to-size (weight) ratio and a low self-discharge characteristic. 
Depending on the battery chemistry the charging characteristics of a battery differs to 
each other. In this project simply what I have done is allows the particular battery to 
follow its charging characteristic curve when they where you could not find in 
conventional charging techniques. The charging process is controlled by the software 
program microcontroller (PIC 16F876).Since the battery chemistries are different for 
different types of batteries, several sets of programs would have to written to the 
controller for each battery given by the manufacturer. 
IV 
There are some theoretical design calculations included for designing of power 
electronics modules. (DC-DC converter, square pulse generator, single rail power & dual 
rail power supplies,etc...) Calculations have been done based on highly theoretical facts. 
Therefore some practical observations are tends to differ from the theoretical approach. 
Most of the theories studied in the power electronic lessons of my M.Sc post graduate were 
widely used in doing above mentioned designs. 
At the beginning the actual target was to built a battery charging panel of 110V,but due to 
some limitations of purchasing of high capacity transformer which suit to this application, 
the project was limited to 40V panel only. But the concept, approach & the guide line would 
be more or less same for the more advanced systems also. 
V 
Acknowledgement 
Thanks are due first to my supervisor, Dr. J.P Karunadasa, for his great insight, 
perspectives, guidance and of humor. My sincere thanks go to the JCT Electrical 
engineering staff of J.C.T (Jaya Container Terminal) of Sri Lanka Ports Authority for 
helping in various ways to clarify things related to my academic works in time with 
excellent corporation and guidance. Sincere gratitude is also extended to the people who 
serve in the Department of Electrical Engineering office. 
I extend sincere gratitude to my superiors, Mr. A.D.T Gunasekara (Chief Electrical 
Engineer of Sri Lanka Ports Authority) who made me to be released from my duties to 
success this project & Mr.H.A.N.S Fernando (Deputy Chief Electrical Engineer) who 
suggested this project concept for this thesis. 
Lastly, I should thank many individuals, friends and colleagues who have not been 
mentioned here personally in making this educational process success. May be I could 
not have made it without your supports. 
VI 
List of Figures 
Figure Page 
Figure 1.3.1 Basic Functional Block 3 
Figure 1.3.2 Typical Characteristics of Ni-Cd battery 4 
Figure 1.3.3 Basic Software Algorithm 6 
Figure 1.4.1 Pin Configuration of PIC 16F876A 8 
Figure 1.4.2 Demonstration Circuit 10 
Figure 1.4.3 PIC Programmer Circuit 10 
Figure 2.1.14 Bridge Rectifier 13 
Figure 2.1.2 DC-DC Converter Circuit 14 
Figure 2.1.3 Single Rail Power Supplies 14 
Figure 2.1.4 Dual Rail Power Supplies 14 
Figure 2.11 (a) Dimensions of the Core 17 
Figure 2.11 (b) Core Loss Curves 19 
Figure 2.12 (a) Pin Configuration of 555 Timer 23 
Figure 2.12 (b) Pin Data of 555 Timer 25 
Figure 2.12 (c) Square Pulse Generator using 555 Timer 26 
Figure 2.13 (a) Pin Configuration of TL082 family 27 
Figure 2.13 (b) Internal View of TL082 28 
Figure 2.13 (c) Frequency & Temperature Characteristics of TL082 28 
Figure 2.13 (d) Load & Voltage Characteristics TL082 29 
Figure 2.13 (e) Switching Amplifier Circuit 30 
Figure 2.14 (a) Figure 2.14-(a) Pin Configuration of TL082 31 
Figure 2.14 (b) Typical Characteristics of LM339 (Vcc=15v;Ta =25°) 33 
Figure 2.14 (b) Comparator Circuit 33 
Figure 2.21 (a) Pin Configuration of PIC16F876A 34 
Figure 2.21 (b) Demonstration Circuit 37 
Figure 2.22(a) ADCONO Register 38 
VII 
Figure 2.22(b) ADC0N1 Register 40 
Figure 11.2 Analog Input Model 42 
Figure 11.3 A/D Conversion TAD Cycle 44 
Figure 11.4 A/D Result Justification 45 
Figure 2.23(a) CCP Module in PWM Mode 46 
Figure 2.23(b) PWM Output 46 
Figure 2.23(c) Data of the PIC16F876A 48 
Figure 3.0 (a) Voltage across the Primary Winding (Theoretical) 55 
Figure 3.0 (b) Voltage across the Primary Winding (Observed) 56 
Figure 3.0 (c) Current of the Primary side of the Converter (Theoretical) 56 
Figure 3.0 (d) Current of the Secondary side of the Converter (Observed) 57 
Figure 3.0 (e) Current through the Secondary Diode 57 
Figure 3.0 (f) Duty Cycle 50% 58 
Figure 3.0(g) Duty Cycle 35% 58 
Figure 3.0 (h) Duty Cycle 10% 59 
Figure 3.21(a) Voltmeter reading & desired value vs. time (8 hrs.) 62 
Figure 3.21(b) Voltage Error vs. Time (8 hrs.) 63 
Figure 3.3 (a) Switching Amplifiers 64 
Figure 3.3 (b) Controller Circuit Operate with the main Panel 64 
Figure 3.3 (c) Fly-Back Transformer of the Converter 65 
Figure 3.3 (d) Overvoltage Comparator Circuit 65 
Figure 3.3 (e) Power Transformer Output to the Dual Supply 66 
Figure 3.3 (f) Top view of the Panel ' 66 
Figure 3.3 (g) 3 Push Buttons Assigned for 3 Battery Types 67 
& the Reset Button (left corner) 
Figure 3.3 (h) 4 -Bridge Rectifier testing with a Variac 67 
Figure 3.3 (i) 3 Sets of Batteries under Charging. 68 
Figure Appendix A: (i) Comparator Symbol 75 
VIII 
List of Tables 
Table 
Table 1: Operating characteristics of TL082 
Table 2: Ratings of the LM339 comparator 
Table 3: Analog / Digital channel configuration 
Table 11.1: TAD vs. maximum device operating frequency 
Table 3.20 Voltmeter reading during eight hours