1

AN INTEGRATED FOUR-PORT DC/DC CONVERTER

FOR RENEWABLE ENERGY APPLICATIONS

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ABSTRACT

This paper proposes a novel converter topology that interfaces four power

ports: two sources, one bidirectional storage port, and one isolated load port. The

proposed four-port dc/dc converter is derived by simply adding two switches and

two diodes to the traditional half-bridge topology. Zero-voltage switching is

realized for all four main switches. Three of the four ports can be tightly regulated

by adjusting their independent duty-cycle values, while the fourth port is left

unregulated to maintain the power balance for the system. Circuit analysis and

design considerations are presented; the dynamic modeling and close-loop design

guidance are given as well. Experimental results verify the proposed topology and

confirm its ability to achieve tight independent control over three power-

processing paths. This topology promises significant savings in component count

and losses for renewable energy power-harvesting systems.

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INTRODUCTION

Present industry is increasingly shifting towards automation. Two principle

components of today’s industrial automations are programmable controllers and

robots. In order to aid the tedious work and to serve the mankind, today there is a

general tendency to develop an intelligent operation.

The proposed system “AN INTEGRATED FOUR-PORT DC/DC

CONVERTERFOR RENEWABLE ENERGY APPLICATIONS” is designed

and developed to accomplish the various tasks in an adverse environment of an

industry. The intelligent This project is an owe to the technical advancement. This

prototype system can be applied effectively and efficiently in an expanded

dimension to fit for the requirement of industrial, research and commercial

applications.

Microcontroller is the heart of the device which handles all the sub devices

connected across it. We have used as microcontroller. It has flash type

reprogrammable memory. It has some peripheral devices to play this project

perform. It also provides sufficient power to inbuilt peripheral devices. We need

not give individually to all devices. The peripheral devices also activates as low

power operation mode. These are the advantages are appear here.

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BLOCK DIAGRAM:

5

BLOCK DIAGRAM DESCRIPTION:

PIC MICRO CONTROLLER

CONCEPTS OF MICROCONTROLLER :

Microcontroller is a general

purpose device, which integrates a number of the components of a

microprocessor system on to single chip. It has inbuilt CPU, memory and

peripherals to make it as a mini computer. A microcontroller combines on to the

same microchip:

The CPU core

Memory(both ROM and RAM)

Some parallel digital i/o

Microcontrollers will combine other devices such as:

A timer module to allow the microcontroller to perform tasks for certain

time periods.

A serial i/o port to allow data to flow between the controller and other

devices such as a PIC or another microcontroller.

An ADC to allow the microcontroller to accept analogue input data for

processing.

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Microcontrollers are :

Smaller in size

Consumes less power

Inexpensive

Micro controller is a stand alone unit ,which can perform functions

on its own without any requirement for additional hardware like i/o ports and

external memory.

The heart of the microcontroller is the CPU core. In the past, this has traditionally

been based on a 8-bit microprocessor unit. For example Motorola uses a basic

6800 microprocessor core in their 6805/6808 microcontroller devices.

In the recent years, microcontrollers have been

developed around specifically designed CPU cores, for example the microchip PIC

range of microcontrollers.

INTRODUCTION TO PIC :

The microcontroller that has been used for this

project is from PIC series. PIC microcontroller is the first RISC based

microcontroller fabricated in CMOS (complimentary metal oxide semiconductor)

that uses separate bus for instruction and data allowing simultaneous access of

program and data memory.

The main advantage of CMOS and RISC

combination is low power consumption resulting in a very small chip size with a

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small pin count. The main advantage of CMOS is that it has immunity to noise

than other fabrication techniques.

PIC (16F877) :

Various microcontrollers offer different kinds of

memories. EEPROM, EPROM, FLASH etc. are some of the memories of which

FLASH is the most recently developed. Technology that is used in pic16F877 is

flash technology, so that data is retained even when the power is switched off.

Easy Programming and Erasing are other features of PIC 16F877.

PIC START PLUS PROGRAMMER :

The PIC start plus development system from

microchip technology provides the product development engineer with a highly

flexible low cost microcontroller design tool set for all microchip PIC micro

devices. The picstart plus development system includes PIC start plus development

programmer and mplab ide.

The PIC start plus programmer gives the product developer

ability to program user software in to any of the supported microcontrollers. The

PIC start plus software running under mplab provides for full interactive control

over the programmer.

SPECIAL FEATURES OF PIC MICROCONTROLLER :

CORE FEATURES :

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• High-performance RISC CPU

• Only 35 single word instructions to learn

• All single cycle instructions except for program branches which are two cycle

• Operating speed: DC - 20 MHz clock input

DC - 200 ns instruction cycle

• Up to 8K x 14 words of Flash Program Memory,

Up to 368 x 8 bytes of Data Memory (RAM)

Up to 256 x 8 bytes of EEPROM data memory

• Pin out compatible to the PIC16C73/74/76/77

• Interrupt capability (up to 14 internal/external

• Eight level deep hardware stack

• Direct, indirect, and relative addressing modes

• Power-on Reset (POR)

• Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)

• Watchdog Timer (WDT) with its own on-chip RC Oscillator for reliable

operation

• Programmable code-protection

• Power saving SLEEP mode

• Selectable oscillator options

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• Low-power, high-speed CMOS EPROM/EEPROM technology

• Fully static design

• In-Circuit Serial Programming (ICSP) via two pins

• Only single 5V source needed for programming capability

• In-Circuit Debugging via two pins

• Processor read/write access to program memory

• Wide operating voltage range: 2.5V to 5.5V

• High Sink/Source Current: 25 mA

• Commercial and Industrial temperature ranges

• Low-power consumption:

< 2mA typical @ 5V, 4 MHz

20mA typical @ 3V, 32 kHz

< 1mA typical standby current

PERIPHERAL FEATURES :

• Timer0: 8-bit timer/counter with 8-bit prescaler

• Timer1: 16-bit timer/counter with prescaler, can be incremented during sleep

via external crystal/clock

• Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler

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• Two Capture, Compare, PWM modules

Capture is 16-bit, max resolution is 12.5 ns,

Compare is 16-bit, max resolution is 200 ns,

PWM max. resolution is 10-bit

• 10-bit multi-channel Analog-to-Digital converter

• Synchronous Serial Port (SSP) with SPI. (Master Mode) and I2C.

(Master/Slave)

• Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with

9- bit address detection.

• Brown-out detection circuitry for Brown-out Reset (BOR)

ARCHITECTURE OF PIC 16F877 :

The complete architecture of PIC

16F877 is shown in the fig 2.1. Table 2.1 gives details about the specifications of

PIC 16F877. Fig 2.2 shows the complete pin diagram of the IC PIC 16F877.

ARCHITECTURE OF PIC 16F877

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SPECIFICATIONS

PIN DIAGRAM OF PIC 16F877

DEVICE PROGRAM FLASH DATA

MEMORY

DATA

EEPROM

PIC

16F877 8K 368 Bytes 256 Bytes

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PIN OUT DESCRIPTION

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Legend: I = input O = output I/O = input/output P = power

— = Not used TTL = TTL input ST = Schmitt Trigger input

Note

1. This buffer is a Schmitt Trigger input when configured as an external interrupt

2. This buffer is a Schmitt Trigger input when used in serial programming mode.

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3. This buffer is a Schmitt Trigger input when configured as general purpose I/O

and a TTL

input when used in the Parallel Slave Port mode (for interfacing to a

microprocessor bus).

4. This buffer is a Schmitt Trigger input when configured in RC oscillator mode

and a

CMOS input otherwise.

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Legend: I = input O = output I/O = input/output P = power

— = Not used TTL = TTL input ST = Schmitt Trigger input

Note :

1. This buffer is a Schmitt Trigger input when configured as an external interrupt.

2. This buffer is a Schmitt Trigger input when used in serial programming mode.

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3. This buffer is a Schmitt Trigger input when configured as general purpose I/O

and a TTL

input when used in the Parallel Slave Port mode (for interfacing to a

microprocessor bus).

4. This buffer is a Schmitt Trigger input when configured in RC oscillator mode

and a

CMOS input otherwise.

2.5 I/O PORTS :

Some pins for these I/O ports are multiplexed with an alternate

function for the peripheral features on the device. In general, when a peripheral is

enabled, that pin may not be used as a general purpose I/O pin.

Additional Information on I/O ports may be found in the IC

micro™ Mid-Range Reference Manual,

PORTA AND THE TRISA REGISTER :

PORTA is a 6-bit wide bi-directional port. The corresponding

data direction register is TRISA. Setting a TRISA bit (=1) will make the

corresponding PORTA pin an input, i.e., put the corresponding output driver in a

Hi-impedance mode. Clearing a TRISA bit (=0) will make the corresponding

PORTA pin an output, i.e., put the contents of the output latch on the selected pin.

Reading the PORTA register reads the status of the

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pins whereas writing to it will write to the port latch. All write operations are read-

modify-write operations. Therefore a write to a port implies that the port pins are

read; this value is modified, and then written to the port data latch. Pin RA4 is

multiplexed with the Timer0 module clock input to become the RA4/T0CKI pin.

The RA4/T0CKI pin is a Schmitt Trigger input and an open drain output. All other

RA port pins have TTL input levels and full CMOS output drivers. Other PORTA

pins are multiplexed with analog inputs and analog VREF input. The operation of

each pin is selected by clearing/setting the control bits in the ADCON1 register

(A/D Control Register1).

The TRISA register controls the direction of the RA pins, even when they

are being used as analog inputs. The user must ensure the bits in the TRISA

register are maintained set when using them as analog inputs.

PORT A FUNCTION

Legend: TTL = TTL input, ST = Schmitt Trigger input

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SUMMARY OF REGISTERS ASSOCIATED WITH PORTA

Legend: x = unknown, u = unchanged, - = unimplemented locations

read as '0'. Shaded cells are not used by PORTA.

PORTB AND TRISB REGISTER :

PORTB is an 8-bit wide bi-directional port.

The corresponding data direction register is TRISB. Setting a TRISB bit (=1) will

make the corresponding PORTB pin an input, i.e., put the corresponding output

driver in a hi-impedance mode. Clearing a TRISB bit (=0) will make the

corresponding PORTB pin an output, i.e., put the contents of the output latch on

the selected pin. Three pins of PORTB are multiplexed with the Low Voltage

Programming function; RB3/PGM, RB6/PGC and RB7/PGD. The alternate

functions of these pins are described in the Special Features Section. Each of the

PORTB pins has a weak internal pull-up. A single control bit can turn on all the

pull-ups.

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This is performed by clearing bit RBPU

(OPTION_REG<7>). The weak pull-up is automatically turned off when the port

pin is configured as an output. The pull-ups are disabled on a Power-on Reset.

Four of PORT B’s pins, RB7:RB4, have an interrupt on

change feature. Only pins configured as inputs can cause this interrupt to occur

(i.e. any RB7:RB4 pin configured as an output is excluded from the interrupt on

change comparison). The input pins (of RB7:RB4) are compared with the old value

latched on the last read of PORTB. The “mismatch” outputs of RB7:RB4 are

OR’ed together to generate the RB Port Change Interrupt with flag bit RBIF

(INTCON<0>). This interrupt can wake the device from SLEEP. The user, in the

interrupt service routine, can clear the interrupt in the following manner:

a) Any read or write of PORTB. This will end the mismatch condition.

b) Clear flag bit RBIF. A mismatch condition will continue to set flag

bit RBIF. Reading PORTB will end the mismatch condition, and allow flag bit

RBIF to be cleared. The interrupt on change feature is recommended for wake-up

on key depression operation and operations where PORTB is only used for the

interrupt on change feature. Polling of PORTB is not recommended while using

the interrupt on change feature. This interrupt on mismatch feature, together with

software configurable pull-ups on these four pins, allow easy interface to a keypad

and make it possible for wake-up on key depression

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PORT B FUNCTIONS

SUMMARY OF REGISTERS ASSOCIATED WITH PORTB

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PORTC AND THE TRISC REGISTER :

PORTC is an 8-bit wide bi-directional port.

The corresponding data direction register is TRISC. Setting a TRISC bit (=1) will

make the corresponding PORTC pin an input, i.e., put the corresponding output

driver in a hi-impedance mode. Clearing a TRISC bit (=0) will make the

corresponding PORTC pin an output, i.e., put the contents of the output latch on

the selected pin. PORTC is multiplexed with several peripheral functions. PORTC

pins have Schmitt Trigger input buffers.

When the I2C module is enabled, the

PORTC (3:4) pins can be configured with normal I2C levels or with SMBUS

levels by using the CKE bit (SSPSTAT <6>). When enabling peripheral functions,

care should be taken in defining TRIS bits for each PORTC pin. Some peripherals

override the TRIS bit to make a pin an output, while other peripherals override the

TRIS bit to make a pin an input. Since the TRIS bit override is in effect while the

peripheral is enabled, read-modify write instructions (BSF, BCF, XORWF) with

TRISC as destination should be avoided. The user should refer to the

corresponding peripheral section for the correct TRIS bit settings.

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PORTC FUNCTIONS

SUMMARY OF REGISTERS ASSOCIATED WITH PORTC

PORTD AND TRISD REGISTERS :

This section is not applicable to the 28-pin

devices. PORTD is an 8-bit port with Schmitt Trigger input buffers. Each pin is

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individually configurable as an input or output. PORTD can be configured as an 8-

bit wide microprocessor Port (parallel slave port) by setting control bit PSPMODE

(TRISE<4>). In this mode, the input buffers are TTL.

PORTD FUNCTIONS

SUMMARY OF REGISTERS ASSOCIATED WITH PORTD

PORTE AND TRISE REGISTER :

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PORTE has three pins RE0/RD/AN5,

RE1/WR/AN6 and RE2/CS/AN7, which are individually configurable as inputs or

outputs. These pins have Schmitt Trigger input buffers.

The PORTE pins become control inputs for the

microprocessor port when bit PSPMODE (TRISE<4>) is set. In this mode, the user

must make sure that the TRISE<2:0> bits are set (pins are configured as digital

inputs). Ensure ADCON1 is configured for digital I/O. In this mode the input

buffers are TTL.

PORTE pins are multiplexed with analog inputs.

When selected as an analog input, these pins will read as '0's. TRISE controls the

direction of the RE pins, even when they are being used as analog inputs. The user

must make sure to keep the pins configured as inputs when using them as analog

inputs.

PORTE FUNCTIONS

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SUMMARY OF REGISTERS ASSOCIATED WITH PORTE

\ MEMORY ORGANISATION :

There are three memory blocks in each of

the PIC16F877 MUC’s. The program memory and Data Memory have separate

buses so that concurrent access can occur.

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PROGRAM MEMORY ORGANISATION :

The PIC16f877 devices have a 13-bit

program counter capable of addressing 8K *14 words of FLASH program

memory. Accessing a location above the physically implemented address will

cause a wraparound.

The RESET vector is at 0000h and the interrupt vector is at 0004h.

DATA MEMORY ORGANISTION :

The data memory is partitioned into multiple

banks which contain the General Purpose Registers and the special functions

Registers. Bits RP1 (STATUS<6) and RP0 (STATUS<5>) are the bank selected

bits.

RP1:RP0 Banks

00 0

01 1

10 2

11 3

Each bank extends up to 7Fh (1238 bytes).

The lower locations of each bank are reserved for the Special Function Registers.

Above the Special Function Registers are General Purpose Registers, implemented

as static RAM. All implemented banks contain special function registers. Some

frequently used special function registers from one bank may be mirrored in

another bank for code reduction and quicker access.

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PIC16F877 REGISTER FILE MAP

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GENERAL PURPOSE REGISTER FILE :

The register file can be accessed either

directly or indirectly through the File Selected Register (FSR). There are some

Special Function Registers used by the CPU and peripheral modules for controlling

the desired operation of the device. These registers are implemented as static

RAM. The Special Function Registers can be classified into two sets; core (CPU)

and peripheral. Those registers associated with the core functions.

INSTRUCTION SET SUMMARY :

Each PIC 16f877 instruction is a 14-bit

word, divided into an OPCODE which specifies the instruction type and one or

more operand which further specify the operation of the instruction. The

PIC16F877 instruction set summary in Table 2.13 lists byte-oriented, bit-

oriented, and literal and control operations. It shows the opcode Field

descriptions.

OPCODE FIELD DESCRIPTIONS

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For byte-oriented instructions, ‘f’

represents a file register designator and ’d’ represents a destination designator. The

file register designator specifies which file register is to be used by the instruction.

The destination designator specified where the result of the operation is to be

placed. If ‘d’ is zero, the result is placed in the w register. If ‘d’ is one, the result is

placed in the file register specified in the instruction.

For bit-oriented instructions, ‘b’ represents

a bit field designator which selects the number of the bit affected by the operation,

which ‘f’ represents the address of the file in which the bits is located. For literal

and control operations, ‘k’ represents an eight or eleven bit constant or literal

value.

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The instruction set is highly orthogonal and is grouped into three basic

categories:

• Byte-oriented operations

• Bit-oriented operations

• Literal and control operations

All instructions are executed within one

single instruction cycle, unless a conditional test is true or the program counter is

changed as a result of an instruction. In this case, the execution takes two

instruction cycles with the second cycle executed as a NOP. One instruction cycle

consists of four oscillator periods. Thus, for an oscillator frequency of 4 MHz, the

normal instruction execution time is 1 ms. If a conditional test is true or the

program counter is changed as a result of an instruction, then the instruction

execution time is 2 ms.

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16F877 INSTRUCTION SET

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GENERAL FORMAT FOR INSTRUCTIONS :

SOLAR PANEL:

33

A solar panel (photovoltaic module or photovoltaic panel) is a packaged

interconnected assembly of solar cells, also known as photovoltaic cells. The solar

panel is used as a component in a larger photovoltaic system to offer electricity for

commercial and residential applications.

Because a single solar panel can only produce a limited amount of power, many

installations contain several panels. This is known as a photovoltaic array. A

photovoltaic installation typically includes an array of solar panels, an inverter,

batteries and interconnection wiring.

Solar panels use light energy (photons) from the sun to generate electricity through

the photovoltaic effect. The structural (load carrying) member of a module can

either be the top layer (superstrate) or the back layer (substrate). The majority of

modules use wafer-based crystalline silicon cells or a thin-film cell based on

cadmium telluride or silicon. Crystalline silicon, which is commonly used in the

wafer form in photovoltaic (PV) modules, is derived from silicon, a commonly

used semi-conductor.

In order to use the cells in practical applications, they must be:

connected electrically to one another and to the rest of the system

protected from mechanical damage during manufacture, transport, installation and

use (in particular against hail impact, wind and snow loads). This is especially

important for wafer-based silicon cells which are brittle.

protected from moisture, which corrodes metal contacts and interconnects, (and

for thin-film cells the transparent conductive oxide layer) thus decreasing

performance and lifetime.

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Most modules are usually rigid, but there are some flexible modules available,

based on thin-film cells.

Electrical connections are made in series to achieve a desired output voltage and/or

in parallel to provide a desired amount of current source capability.

Diodes are included to avoid overheating of cells in case of partial shading. Since

cell heating reduces the operating efficiency it is desirable to minimize the heating.

Very few modules incorporate any design features to decrease temperature,

however installers try to provide good ventilation behind the module.[1]

New designs of module include concentrator modules in which the light is

concentrated by an array of lenses or mirrors onto an array of small cells. This

allows the use of cells with a very high-cost per unit area (such as gallium

arsenide) in a cost-competitive way.

Depending on construction, the photovoltaic can cover a range of frequencies of

light and can produce electricity from them, but sometimes cannot cover the entire

solar spectrum (specifically, ultraviolet, infrared and low or diffused light). Hence

much of incident sunlight energy is wasted when used for solar panels, although

they can give far higher efficiencies if illuminated with monochromatic light.

Another design concept is to split the light into different wavelength ranges and

direct the beams onto different cells tuned to the appropriate wavelength ranges.[2]

This is projected to raise efficiency by 50%. Also, the use of infrared photovoltaic

cells can increase the efficiencies, producing power at night.

BATTERY:

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An electrical battery is one or more electrochemical cells that convert stored

chemical energy into electrical energy.[1] Since the invention of the first battery (or

"voltaic pile") in 1800 by Alessandro Volta, batteries have become a common

power source for many household and industrial applications. According to a 2005

estimate, the worldwide battery industry generates US$48 billion in sales each

year,[2] with 6% annual growth.[3]

There are two types of batteries: primary batteries (disposable batteries), which are

designed to be used once and discarded when they are exhausted, and secondary

batteries (rechargeable batteries), which are designed to be recharged and used

multiple times. Miniature cells are used to power devices such as hearing aids and

wristwatches; larger batteries provide standby power for telephone exchanges or

computer data centers.

History

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The symbol for a battery in a circuit diagram. It originated as a schematic drawing

of the earliest type of battery, a voltaic pile.

Strictly, a battery is a collection of multiple electrochemical cells, but in popular

usage battery often refers to a single cell.[1] The first electrochemical cell was

developed by the Italian physicist Alessandro Volta in 1792, and in 1800 he

invented the first battery—for him, a "pile" of cells.[4]

The usage of "battery" to describe electrical devices dates to Benjamin Franklin,

who in 1748 described multiple Leyden jars (early electrical capacitors) by analogy

to a battery of cannons.[5] Thus Franklin's usage to describe multiple Leyden jars

predated Volta's use of multiple galvanic cells.[6]. It is speculated, but not

established, that several ancient artifacts consisting of copper sheets and iron bars,

and known as Baghdad batteries may have been galvanic cells.[7]

Volta's work was stimulated by the Italian anatomist and physiologist Luigi

Galvani, who in 1780 noticed that dissected frog's legs would twitch when struck

by a spark from a Leyden jar, an external source of electricity.[8] In 1786 he noticed

that twitching would occur during lightning storms.[9] After many years Galvani

learned how to produce twitching without using any external source of electricity.

In 1791 he published a report on "animal electricity."[10] He created an electric

circuit consisting of the frog's leg (FL) and two different metals A and B, each

37

metal touching the frog's leg and each other, thus producing the circuit A-FL-B-A-

FL-B...etc. In modern terms, the frog's leg served as both the electrolyte and the

sensor, and the metals served as electrodes. He noticed that even though the frog

was dead, its legs would twitch when he touched them with the metals.

Within a year, Volta realized the frog's moist tissues could be replaced by

cardboard soaked in salt water, and the frog's muscular response could be replaced

by another form of electrical detection. He already had studied the electrostatic

phenomenon of capacitance, which required measurements of electric charge and

of electrical potential ("tension"). Building on this experience, Volta was able to

detect electric current through his system, also called a Galvanic cell. The terminal

voltage of a cell that is not discharging is called its electromotive force (emf), and

has the same unit as electrical potential, named (voltage) and measured in volts, in

honor of Volta. In 1800, Volta invented the battery by placing many voltaic cells in

series, literally piling them one above the other. This voltaic pile gave a greatly

enhanced net emf for the combination,[11] with a voltage of about 50 volts for a 32-

cell pile.[12] In many parts of Europe batteries continue to be called piles.[13][14]

Volta did not appreciate that the voltage was due to chemical reactions. He thought

that his cells were an inexhaustible source of energy,[15] and that the associated

chemical effects (e.g. corrosion) were a mere nuisance, rather than an unavoidable

consequence of their operation, as Michael Faraday showed in 1834.[16] According

to Faraday, cations (positively charged ions) are attracted to the cathode,[17] and

anions (negatively charged ions) are attracted to the anode.[18]

Although early batteries were of great value for experimental purposes, in practice

their voltages fluctuated and they could not provide a large current for a sustained

period. Later, starting with the Daniell cell in 1836, batteries provided more

38

reliable currents and were adopted by industry for use in stationary devices,

particularly in telegraph networks where they were the only practical source of

electricity, since electrical distribution networks did not exist at the time.[19] These

wet cells used liquid electrolytes, which were prone to leakage and spillage if not

handled correctly. Many used glass jars to hold their components, which made

them fragile. These characteristics made wet cells unsuitable for portable

appliances. Near the end of the nineteenth century, the invention of dry cell

batteries, which replaced the liquid electrolyte with a paste, made portable

electrical devices practical.[20]

Since then, batteries have gained popularity as they became portable and useful for

a variety of purposes.[21]

How batteries work

39

A voltaic cell for demonstration purposes. In this example the two half-cells are

linked by a salt bridge separator that permits the transfer of ions, but not water

molecules.

A battery is a device that converts chemical energy directly to electrical energy.[22]

It consists of a number of voltaic cells; each voltaic cell consists of two half cells

connected in series by a conductive electrolyte containing anions and cations. One

half-cell includes electrolyte and the electrode to which anions (negatively charged

ions) migrate, i.e., the anode or negative electrode; the other half-cell includes

electrolyte and the electrode to which cations (positively charged ions) migrate,

i.e., the cathode or positive electrode. In the redox reaction that powers the battery,

reduction (addition of electrons) occurs to cations at the cathode, while oxidation

(removal of electrons) occurs to anions at the anode.[23] The electrodes do not touch

each other but are electrically connected by the electrolyte. Many cells use two

half-cells with different electrolytes. In that case each half-cell is enclosed in a

container, and a separator that is porous to ions, but not the bulk of the electrolytes,

prevents mixing.

Each half cell has an electromotive force (or emf), determined by its ability to

drive electric current from the interior to the exterior of the cell. The net emf of the

40

cell is the difference between the emfs of its half-cells, as first recognized by

Volta.[12] Therefore, if the electrodes have emfs and , then the net emf is

; in other words, the net emf is the difference between the reduction

potentials of the half-reactions.[24]

The electrical driving force or across the terminals of a cell is known as the

terminal voltage (difference) and is measured in volts.[25] The terminal voltage of a

cell that is neither charging nor discharging is called the open-circuit voltage and

equals the emf of the cell. Because of internal resistance[26], the terminal voltage of

a cell that is discharging is smaller in magnitude than the open-circuit voltage and

the terminal voltage of a cell that is charging exceeds the open-circuit voltage.[27]

An ideal cell has negligible internal resistance, so it would maintain a constant

terminal voltage of until exhausted, then dropping to zero. If such a cell

maintained 1.5 volts and stored a charge of one coulomb then on complete

discharge it would perform 1.5 joule of work.[25] In actual cells, the internal

resistance increases under discharge,[26] and the open circuit voltage also decreases

under discharge. If the voltage and resistance are plotted against time, the resulting

graphs typically are a curve; the shape of the curve varies according to the

chemistry and internal arrangement employed.[28]

As stated above, the voltage developed across a cell's terminals depends on the

energy release of the chemical reactions of its electrodes and electrolyte. Alkaline

and carbon-zinc cells have different chemistries but approximately the same emf of

1.5 volts; likewise NiCd and NiMH cells have different chemistries, but

approximately the same emf of 1.2 volts.[29] On the other hand the high

electrochemical potential changes in the reactions of lithium compounds give

lithium cells emfs of 3 volts or more.[30]

41

Categories and types of batteries

42

43

From top to bottom: SR41/AG3, SR44/AG13 (button cells), a 9-volt PP3 battery,

an AAA cell, an AA cell, a C cell, a D Cell, and a large 3R12. The ruler's unit is in

centimeters.

Batteries are classified into two broad categories, each type with advantages and

disadvantages.[31]

Primary batteries irreversibly (within limits of practicality) transform

chemical energy to electrical energy. When the initial supply of reactants is

exhausted, energy cannot be readily restored to the battery by electrical

means.[32]

Secondary batteries can be recharged; that is, they can have their chemical

reactions reversed by supplying electrical energy to the cell, restoring their

original composition.[33]

Historically, some types of primary batteries used, for example, for telegraph

circuits, were restored to operation by replacing the components of the battery

consumed by the chemical reaction.[34] Secondary batteries are not indefinitely

rechargeable due to dissipation of the active materials, loss of electrolyte and

internal corrosion.

Primary batteries

Primary batteries can produce current immediately on assembly. Disposable

batteries are intended to be used once and discarded. These are most commonly

used in portable devices that have low current drain, are only used intermittently,

or are used well away from an alternative power source, such as in alarm and

communication circuits where other electric power is only intermittently available.

Disposable primary cells cannot be reliably recharged, since the chemical reactions

44

are not easily reversible and active materials may not return to their original forms.

Battery manufacturers recommend against attempting to recharge primary cells.[35]

Common types of disposable batteries include zinc-carbon batteries and alkaline

batteries. Generally, these have higher energy densities than rechargeable

batteries,[36] but disposable batteries do not fare well under high-drain applications

with loads under 75 ohms (75 Ω).[31]

Secondary batteries

Secondary batteries must be charged before use; they are usually assembled with

active materials in the discharged state. Rechargeable batteries or secondary cells

can be recharged by applying electric current, which reverses the chemical

reactions that occur during its use. Devices to supply the appropriate current are

called chargers or rechargers.

The oldest form of rechargeable battery is the lead-acid battery.[37] This battery is

notable in that it contains a liquid in an unsealed container, requiring that the

battery be kept upright and the area be well ventilated to ensure safe dispersal of

the hydrogen gas produced by these batteries during overcharging. The lead-acid

battery is also very heavy for the amount of electrical energy it can supply. Despite

this, its low manufacturing cost and its high surge current levels make its use

common where a large capacity (over approximately 10Ah) is required or where

the weight and ease of handling are not concerns.

45

A common form of the lead-acid battery is the modern car battery, which can

generally deliver a peak current of 450 amperes.[38] An improved type of liquid

electrolyte battery is the sealed valve regulated lead acid (VRLA) battery, popular

in the automotive industry as a replacement for the lead-acid wet cell. The VRLA

battery uses an immobilized sulfuric acid electrolyte, reducing the chance of

leakage and extending shelf life.[39] VRLA batteries have the electrolyte

immobilized, usually by one of two means:

Gel batteries (or "gel cell") contain a semi-solid electrolyte to prevent

spillage.

Absorbed Glass Mat (AGM) batteries absorb the electrolyte in a special

fiberglass matting.

Other portable rechargeable batteries include several "dry cell" types, which are

sealed units and are therefore useful in appliances such as mobile phones and

laptop computers. Cells of this type (in order of increasing power density and cost)

include nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH)

and lithium-ion (Li-ion) cells.[40] By far, Li-ion has the highest share of the dry cell

rechargeable market.[3] Meanwhile, NiMH has replaced NiCd in most applications

due to its higher capacity, but NiCd remains in use in power tools, two-way radios,

and medical equipment.[3] NiZn is a new technology that is not yet well established

commercially.

Recent developments include batteries with embedded functionality such as

USBCELL, with a built-in charger and USB connector within the AA format,

46

enabling the battery to be charged by plugging into a USB port without a

charger,[41] and low self-discharge (LSD) mix chemistries such as Hybrio,[42]

ReCyko,[43] and Eneloop,[44] where cells are precharged prior to shipping.

WIND MILL:

A windmill is a machine which converts the energy of wind into rotational motion

by means of adjustable vanes called sails. The main use is for a grinding mill

powered by the wind, reducing a solid or coarse substance into pulp or minute

grains, by crushing, grinding, or pressing.[1][2] Windmills have also provided

energy to sawmills, paper mills, hammermills, and windpumps for obtaining fresh

water from underground or for drainage (especially of land below sea level).

47

Vertical-axis windmills

The first practical windmills were the vertical axle windmills invented in eastern

Persia (what is now Afghanistan), as recorded by the Persian geographer Estakhri

in the 9th century.[6][7] The authenticity of an earlier anecdote of a windmill

involving the second caliph Umar (AD 634–644) is questioned on the grounds that

it appears in a 10th-century document.[8] Made of six to twelve sails covered in

48

reed matting or cloth material, these windmills were used to grind grain or draw up

water, and were quite different from the later European horizontal-axis versions.

Windmills were in widespread use across the Middle East and Central Asia, and

later spread to China and India from there.[9]

Some popular treatments of the subject have speculated that, by the 9th century,

the Persian-style vertical-axle mills spread to Europe through Al-Andalus (Islamic

Spain).[10] This has been denied by the specialist of medieval European technology,

Lynn White Jr., who points out that there is no evidence (archaeological or

documentary) that the Afghanistan-style vertical-axle windmill spread as far west

as Al-Andalus,[11] and notes that "all Iberian windmills rotated on horizontal axles

until towards the middle of the fifteenth century."[12] Another historian of

technology, Michael Jonathan Taunton Lewis, suggested an alternative route of

transmission for the Islamic horizontal-shaft windmill, with its diffusion to the

Byzantine Empire and its subsequent transformation into the vertical-shaft

windmill in Europe.[13] Late medieval vertical-axle windmills similar to the

Islamic/Persian design can be found along this route, particularly in Karpathos,

Greece, and Kandia, Crete. The Crusades has also been suggested as another

possible route of transmission, though in the sense of "stimulus diffusion," where

the idea was diffused rather than the technology itself.[14] However, the debate

about whether the European vertical-shaft windmill evolved from the Islamic

horizontal-shaft windmill or was an independent development remains

unresolved.[13]

49

Horizontal-axis windmills

Horizontal-axle windmills that turn to face the wind

In northwestern Europe, the horizontal-axle or vertical windmill (so called due to

the dimension of the movement of its sails) dates from the last quarter of the 12th

century in the triangle of northern France, eastern England and Flanders. Lynn

White Jr. claims that the first certain reference to the European horizontal-axle

windmill is dated to 1185 in Weedley, Yorkshire.[16] (This predates Joseph

Needham's claim that the earliest known reference is from the 1191 chronicle of

Jocelin of Brakelond, in which a Dean Herbert of East Anglia supposedly

competed with the mills of the abbey of Bury St Edmunds).[17] These earliest mills

were used to grind cereals. The evidence at present is that the earliest type was the

sunk post mill, so named because of the large upright post on which the mill's main

structure (the "body" or "buck") is balanced. By mounting the body this way, the

50

mill is able to rotate to face the wind direction; an essential requirement for

windmills to operate economically in North-Western Europe, where wind

directions are variable. By the end of the thirteenth century the masonry tower mill,

on which only the timber cap rotated rather than the whole body of the mill, had

been introduced. In the Netherlands these stone towerlike mills are called "round or

eight-sided stone stage mills, ground-sailers (windmills with sails reaching almost

down to the ground), mound mills, etc." (Dutch: ronde/achtkante stenen stelling

molens, grond-zeilers, beltmolens, etc.). Dutch tower mills ("torenmolens") are

always cylindrical (such as atop castle or city wall towers). Because only the cap of

the tower mill needed to be turned the main structure could be made much taller,

allowing the sails to be made longer, which enabled them to provide useful work

even in low winds. Such mills often have a small auxiliary set of sails called a

fantail at the rear of the cap and at right angles to the sails; this rotates the cap

through gearing so that the sails face into the wind.

51

Multi-sailed windmills

The majority of windmills had four sails. An increase in the number of sails meant

that an increase in power could be obtained, at the expense of an increase in the

weight of the sail assembly. The earliest record of a multi-sailed mill in the United

Kingdom was the five sail Flint Mill, Leeds, mentioned in a report by John

Smeaton in 1774. Multi-sailed windmills were said to run smoother than four sail

windmills. In Lincolnshire, more multi-sailed windmills were found than anywhere

else in the United Kingdom. There were five, six and eight sail windmills.[26]

If a four sail windmill suffers a damaged sail, the one opposite can be removed and

the mill will work with two sails, generating about 60% of the power that it would

with all four sails. A six sail mill can run with two, three, four or six sails. An eight

sail mill can run with two, four, six or eight sails, thus allowing a number of

options if an accident occurs. A five sail mill can only run with all five sails. If one

is damaged then the mill is stopped until it is replaced.

MOSFET DRIVER CIRCUIT:

52

Circuit description:

This circuit is designed to control the MOSFET depending upon the signals from PIC. In

our circuit there is two transistor connected back to back. we use npn transistor as a Q1 and pnp

transistor as a Q2 transistor. When high pulse signal is given to base of the Q1 transistors, the transistor

is conducting and shorts the collector and emitter terminal and zero signals is given to base of the Q2

transistor. So Q2 is turned ON so MOSFET’S gate get high pulse and it will be turned ON.

When low pulse is given to base of transistor Q1 transistor, the transistor is turned OFF. Now

12v is given to base of Q2 transistor so the Q2 is turned OFF. Now MOSFET’S gate get low pulse now it

goes to off state.

53

Voltage Signal from Transistor Q1 Transistor Q2 MOSFET

PIC Microcontroller

1 on on on

0 off off off

MOSFET

MOSFET operation

For the operation of MOS devices discussed next, an authoritative reference is

Tsividis [2].

Metal–oxide–semiconductor structure

Metal–oxide–semiconductor structure on P-type silicon

A traditional metal–oxide–semiconductor (MOS) structure is obtained by

depositing a layer of silicon dioxide (SiO2) and a layer of metal (polycrystalline

silicon is commonly used instead of metal) on top of a semiconductor die. As the

54

silicon dioxide is a dielectric material its structure is equivalent to a planar

capacitor, with one of the electrodes replaced by a semiconductor.

When a voltage is applied across a MOS structure, it modifies the distribution of

charges in the semiconductor. If we consider a P-type semiconductor (with NA the

density of acceptors, p the density of holes; p = NA in neutral bulk), a positive

voltage, VGB, from gate to body (see figure) creates a depletion layer by forcing the

positively charged holes away from the gate-insulator/semiconductor interface,

leaving exposed a carrier-free region of immobile, negatively charged acceptor

ions. See doping (semiconductor). If VGB is high enough, a high concentration of

negative charge carriers forms in an inversion layer located in a thin layer next to

the interface between the semiconductor and the insulator. (Unlike the MOSFET,

discussed below, where the inversion layer electrons are supplied rapidly from the

source/drain electrodes, in the MOS capacitor they are produced much more

slowly by thermal generation through carrier generation and recombination centers

in the depletion region.) Conventionally, the gate voltage at which the volume

density of electrons in the inversion layer is the same as the volume density of

holes in the body is called the threshold voltage.

This structure with P-type body is the basis of the N-type MOSFET, which

requires the addition of an N-type source and drain regions.

55

1.1.1 MOSFET structure and channel formation

Cross section of an NMOS without channel formed: OFF state

Cross section of an NMOS with channel formed: ON state

A metal–oxide–semiconductor field-effect transistor (MOSFET) is based on the

modulation of charge concentration by a MOS capacitance between a body

electrode and a gate electrode located above the body and insulated from all other

device regions by an oxide. The MOSFET includes two additional terminals

(source and drain), each connected to individual highly doped regions that are

separated by the body region. These regions can be either p or n type, but they

must both be of the same type, and of opposite type to the body region. The highly

56

doped source and drain regions typically are denoted by a '+' following the type of

doping. The body is not highly doped, as denoted by the lack of a '+' sign.

If the MOSFET is an n-channel or nMOS FET, then the source and drain are 'n+'

regions and the body is a 'p' region. As described above, with sufficient gate

voltage, above a threshold voltage value, electrons from the source (and possibly

also the drain) enter the inversion layer or n-channel at the interface between the p

region and the oxide. This conducting channel extends between the source and the

drain, and current is conducted through it when a voltage is applied between source

and drain.

For gate voltages below the threshold value, the channel is lightly populated, and

only a very small subthreshold leakage current can flow between the source and

the drain.

If the MOSFET is a p-channel or pMOS FET, then the source and drain are 'p+'

regions and the body is a 'n' region. When a negative gate-source voltage (positive

source-gate) is applied, it creates a p-channel at the surface of the n region,

analogous to the n-channel case, but with opposite polarities of charges and

voltages. When a voltage less negative than the threshold value (a negative voltage

for p-Channel) is applied between gate and source, the channel disappears and only

a very small subthreshold current can flow between the source and the drain.

The source is so named because it is the source of the charge carriers (electrons for

n-channel, holes for p-channel) that flow through the channel; similarly, the drain

is where the charge carriers leave the channel.

57

1.1.2 Modes of operation

The operation of a MOSFET can be separated into three different modes,

depending on the voltages at the terminals. In the following discussion, a

simplified algebraic model is used that is accurate only for old technology. Modern

MOSFET characteristics require computer models that have rather more complex

behavior. For example, see Liu [3] and the device modeling list in [1].

For an enhancement-mode, n-channel MOSFET the three operational modes are:

Cut-off or Sub-threshold or Weak Inversion Mode

When V GS < Vth:

where Vth is the threshold voltage of the device.

According to the basic threshold model, the transistor is turned off, and there is

no conduction between drain and source. In reality, the Boltzmann distribution of

electron energies allows some of the more energetic electrons at the source to

enter the channel and flow to the drain, resulting in a subthreshold current that is

an exponential function of gate–source voltage. While the current between drain

and source should ideally be zero when the transistor is being used as a turned-

off switch, there is a weak-inversion current, sometimes called subthreshold

leakage.

In weak inversion the current varies exponentially with gate-to-source bias VGS as

given approximately by:[4][5]

,

where ID0 = current at VGS = Vth and the slope factor n is given by

58

n = 1 + CD / COX,

with CD = capacitance of the depletion layer and COX = capacitance of the oxide

layer. In a long-channel device, there is no drain voltage dependence of the

current once VDS > > VT, but as channel length is reduced drain-induced barrier

lowering introduces drain voltage dependence that depends in a complex way

upon the device geometry (for example, the channel doping, the junction doping

and so on). Frequently threshold voltage Vth for this mode is defined as the gate

voltage at which a selected value of current ID0 occurs, for example, ID0 = 1 μA,

which may not be the same Vth-value used in the equations for the following

modes.

ISOLATION TRANSFORMER

An isolation transformer is a transformer used to transfer electrical power from a

source of alternating current (AC) power to some equipment or device while

isolating the powered device from the power source, usually for safety. Isolation

transformers provide galvanic isolation and are used to protect against electric

shock, to suppress electrical noise in sensitive devices, or to transfer power

between two circuits which must not be connected together.

Suitably designed isolation transformers block interference caused by ground

loops. Isolation transformers with electrostatic shields are used for power supplies

for sensitive equipment such as computers or laboratory instruments.

59

Strictly speaking any true transformer, whether used to transfer signals or power, is

isolating, as the primary and secondary are not connected by conductors but only

by induction.

However, only transformers whose primary purpose is to isolate circuits (opposed

to the more common transformer function of voltage conversion), are routinely

described as isolation transformers.

Given this function, a transformer sold for isolation is often built with special

insulation between primary and secondary, and is tested, specified, and marked to

withstand a high voltage between windings, typically in the 1000 to 4000 volt

range.

Sometimes the term is exceptionally used to clarify that some transformer,

although not primarily intended for isolation, is a true transformer rather than an

autotransformer (whose primary and secondary are not isolated from each other).[1]

Even step-down power transformers required, amongst other things, to protect low-

voltage equipment from mains voltage by isolating the secondary and primary such

as are used in older "wall warts", are not usually described specifically as

"isolation transformers".

Some very small transformers—e.g. 4 transformers in one tiny dual in-line (DIL)

chip package—used to isolate high-frequency low-voltage (logic) pulse circuits

(e.g., 500V RMS primary–secondary for one second), are described as isolation

transformers[1][2]

Isolation transformers are commonly designed with careful attention to capacitive

coupling between the two windings. The capacitance between primary and

secondary windings would also couple AC current from the primary to the

60

secondary. A grounded Faraday shield between the primary and the secondary

greatly reduces the coupling of common-mode noise. This may be another winding

or a metal strip surrounding a winding.

Differential noise can magnetically couple from the primary to the secondary of an

isolation transformer, and must be filtered out if a problem.

Sometimes a balanced secondary with an earthed center is used. This can reduce

earth leakage in equipment used in wet locations. The maximum voltage above

earth is halved, reducing the risk of shock if anything live is touched.

Applications

In electronics testing and servicing isolation transformer is a 1:1 (under load)

power transformer used for safety. Without it, exposed live metal in a device under

test is at a hazardous voltage relative to grounded objects such as a heating radiator

or oscilloscope ground lead (a particular hazard with some old vacuum-tube

equipment with live chassis). With the transformer, as there is no conductive

connection between transformer secondary and earth, there is no danger in

touching a live part of the circuit while another part of the body is earthed.

Electrical isolation is considered to be particularly important on medical

equipment, and special standards apply. Often the system must additionally be

designed so that fault conditions do not interrupt power, but generate a warning.[3]

Isolation transformers are also used for the power supply of devices not at ground

potential. An example is the Austin transformer for the power supply of air-traffic

obstacle warning lamps on radio antenna masts. Without the isolation transformer,

61

the lighting circuits on the mast would conduct radio-frequency energy to ground

through the power supply.

Metal boats are subject to corrosion if they use earthed power from shore when

moored, due to galvanic currents that flow through the water between shore earth

and the hull. This can be avoided by using an isolation transformer with the

primary and case connected to shore earth, and the secondary "floating".[4] A metal

safety screen between primary and secondary is connected to shore earth; in the

event of a fault current in the primary (due, e.g., to insulation breakdown) it will

cause the fault current to return and trip a shore-based circuit breaker rather than

making the hull live.

62

OVERALL CIRCUIT DIAGRAM:

POWER SUPPLY:

Block diagram

The ac voltage, typically 220V rms, is connected to a transformer, which

steps that ac voltage down to the level of the desired dc output. A diode rectifier

then provides a full-wave rectified voltage that is initially filtered by a simple

capacitor filter to produce a dc voltage. This resulting dc voltage usually has some

ripple or ac voltage variation.

A regulator circuit removes the ripples and also remains the same dc value

even if the input dc voltage varies, or the load connected to the output dc voltage

changes. This voltage regulation is usually obtained using one of the popular

voltage regulator IC units.

Block diagram (Power supply)

Working principle

63

Transformer

The potential transformer will step down the power supply voltage (0-

230V) to (0-6V) level. Then the secondary of the potential transformer will be

connected to the precision rectifier, which is constructed with the help of op–

amp. The advantages of using precision rectifier are it will give peak voltage

output as DC, rest of the circuits will give only RMS output.

Bridge rectifier

When four diodes are connected as shown in figure, the circuit is called as

bridge rectifier. The input to the circuit is applied to the diagonally opposite

corners of the network, and the output is taken from the remaining two corners.

Let us assume that the transformer is working properly and there is a

positive potential, at point A and a negative potential at point B. the positive

potential at point A will forward bias D3 and reverse bias D4.

The negative potential at point B will forward bias D1 and reverse D2. At

this time D3 and D1 are forward biased and will allow current flow to pass

through them; D4 and D2 are reverse biased and will block current flow.

The path for current flow is from point B through D1, up through RL,

through D3, through the secondary of the transformer back to point B. this path is

indicated by the solid arrows. Waveforms (1) and (2) can be observed across D1

and D3.

64

One-half cycle later the polarity across the secondary of the transformer

reverse, forward biasing D2 and D4 and reverse biasing D1 and D3. Current flow

will now be from point A through D4, up through RL, through D2, through the

secondary of T1, and back to point A. This path is indicated by the broken arrows.

Waveforms (3) and (4) can be observed across D2 and D4. The current flow

through RL is always in the same direction. In flowing through RL this current

develops a voltage corresponding to that shown waveform (5). Since current

flows through the load (RL) during both half cycles of the applied voltage, this

bridge rectifier is a full-wave rectifier.

One advantage of a bridge rectifier over a conventional full-wave rectifier is

that with a given transformer the bridge rectifier produces a voltage output that is

nearly twice that of the conventional full-wave circuit.

This may be shown by assigning values to some of the components shown in

views A and B. assume that the same transformer is used in both circuits. The peak

voltage developed between points X and y is 1000 volts in both circuits. In the

conventional full-wave circuit shown—in view A, the peak voltage from the center

tap to either X or Y is 500 volts. Since only one diode can conduct at any instant,

the maximum voltage that can be rectified at any instant is 500 volts.

The maximum voltage that appears across the load resistor is nearly-but

never exceeds-500 v0lts, as result of the small voltage drop across the diode. In the

bridge rectifier shown in view B, the maximum voltage that can be rectified is the

full secondary voltage, which is 1000 volts. Therefore, the peak output voltage

across the load resistor is nearly 1000 volts. With both circuits using the same

transformer, the bridge rectifier circuit produces a higher output voltage than the

conventional full-wave rectifier circuit.

65

IC voltage regulators

Voltage regulators comprise a class of widely used ICs. Regulator IC

units contain the circuitry for reference source, comparator amplifier, control

device, and overload protection all in a single IC. IC units provide regulation of

either a fixed positive voltage, a fixed negative voltage, or an adjustably set

voltage. The regulators can be selected for operation with load currents from

hundreds of milli amperes to tens of amperes, corresponding to power ratings

from milli watts to tens of watts.

66

Circuit diagram (Power supply)

A fixed three-terminal voltage regulator has an unregulated dc input

voltage, Vi, applied to one input terminal, a regulated dc output voltage, Vo, from

a second terminal, with the third terminal connected to ground.

The series 78 regulators provide fixed positive regulated voltages from 5 to

24 volts. Similarly, the series 79 regulators provide fixed negative regulated

voltages from 5 to 24 volts.

For ICs, microcontroller, LCD --------- 5 volts

For alarm circuit, op-amp, relay circuits ---------- 12 volts

67

LCD DISPLAY WITH PIC

We connect the lcd display with PIC through PORT D.

68

PORTD AND TRISD REGISTER :

PORTD is an 8-bit wide bi-directional port.

The corresponding data direction register is TRISD. Setting a TRISD bit (=1) will

make the corresponding PORTD pin an input, i.e., put the corresponding output

driver in a hi-impedance mode. Clearing a TRISD bit (=0) will make the

corresponding PORTD pin an output.

PORTD AND TRISD REGISTERS:

This section is not applicable to the 28-pin

devices. PORTD is an 8-bit port with Schmitt Trigger input buffers. Each pin is

individually configurable as an input or output. PORTD can be configured as an 8-

bit wide microprocessor Port (parallel slave port) by setting control bit PSPMODE

(TRISE<4>). In this mode, the input buffers are TTL.

PORTD FUNCTIONS

SUMMARY OF REGISTERS ASSOCIATED WITH PORTD

69

a) Any read or write of PORTD. This will end the mismatch

condition.

b) Clear flag bit RBIF. A mismatch condition will continue to

set flag bit RBIF. Reading PORTD will end the mismatch condition, and

allow flag bit RBIF to be cleared. The interrupt on change feature is

recommended for wake-up on key depression operation and operations

where PORTD is only used for the interrupt on change feature. Polling of

PORTD is not recommended while using the interrupt on change feature.

This interrupt on mismatch feature, together with software configurable pull-

ups on these four pins, allow easy interface to a keypad and make it possible

for wake-up on key depression

70

71

PCB DESIGN

Design and Fabrication of Printed circuit boards

INTRODUCTION:

Printed circuit boards, or PCBs, form the core of electronic equipment

domestic and industrial. Some of the areas where PCBs are intensively used are

computers, process control, telecommunications and instrumentation.

MANUFATCURING:

The manufacturing process consists of two methods; print and etch, and

print, plate and etch. The single sided PCBs are usually made using the print and

etch method. The double sided plate through – hole (PTH) boards are made by the

print plate and etch method.

The production of multi layer boards uses both the methods. The inner layers

are printed and etch while the outer layers are produced by print, plate and etch

after pressing the inner layers.

SOFTWARE:

72

The software used in our project to obtain the schematic layout is

MICROSIM.

PANELISATION:

Here the schematic transformed in to the working positive/negative films. The

circuit is repeated conveniently to accommodate economically as many circuits

as possible in a panel, which can be operated in every sequence of subsequent

steps in the PCB process. This is called penalization. For the PTH boards, the

next operation is drilling.

DRILLING:

PCB drilling is a state of the art operation. Very small holes are drilled with

high speed CNC drilling machines, giving a wall finish with less or no smear or

epoxy, required for void free through hole plating.

PLATING:

The heart of the PCB manufacturing process. The holes drilled in the board

are treated both mechanically and chemically before depositing the copper by the

electro less copper platting process.

73

ETCHING:

Once a multiplayer board is drilled and electro less copper deposited, the

image available in the form of a film is transferred on to the out side by photo

printing using a dry film printing process. The boards are then electrolytic plated

on to the circuit pattern with copper and tin. The tin-plated deposit serves an etch

resist when copper in the unwanted area is removed by the conveyor’s spray

etching machines with chemical etch ants. The etching machines are attached to an

automatic dosing equipment, which analyses and controls etch ants concentrations

SOLDERMASK:

Since a PCB design may call for very close spacing between conductors, a

solder mask has to be applied on the both sides of the circuitry to avoid the

bridging of conductors. The solder mask ink is applied by screening. The ink is

dried, exposed to UV, developed in a mild alkaline solution and finally cured by

both UV and thermal energy.

HOT AIR LEVELLING:

74

After applying the solder mask, the circuit pads are soldered using the hot air

leveling process. The bare bodies fluxed and dipped in to a molten solder bath.

While removing the board from the solder bath, hot air is blown on both sides of

the board through air knives in the machines, leaving the board soldered and

leveled. This is one of the common finishes given to the boards. Thus the double

sided plated through whole printed circuit board is manufactured and is now ready

for the components to be soldered.

75

MPLAB

MPLAB IDE is an integrated development environment that provides

development engineers with the flexibility to develop and debug firmware for

various Microchip devices

MPLAB IDE is a Windows-based Integrated Development Environment for the

Microchip Technology Incorporated PICmicrocontroller (MCU) and dsPIC digital

signal controller (DSC) families. In the MPLAB IDE, you can:

Create source code using the built-in editor.

Assemble, compile and link source code using various language tools. An

assembler, linker and librarian come with MPLAB IDE. C compilers are

available from Microchip and other third party vendors.

Debug the executable logic by watching program flow with a simulator,

such as MPLAB SIM, or in real time with an emulator, such as MPLAB

ICE. Third party emulators that work with MPLAB IDE are also available.

Make timing measurements.

View variables in Watch windows.

Program firmware into devices with programmers such as PICSTART Plus

or PRO MATE II.

Find quick answers to questions from the MPLAB IDE on-line Help.

76

MPLAB SIMULATOR

MPLAB SIM is a discrete-event simulator for the PIC microcontroller (MCU)

families. It is integrated into MPLAB IDE integrated development environment.

The MPLAB SIM debugging tool is designed to model operation of Microchip

Technology's PIC microcontrollers to assist users in debugging software for these

devices

IC PROG

The PRO MATE II is a Microchip microcontroller device programmer. Through

interchangeable programming socket modules, PRO MATE II enables you to

quickly and easily program the entire line of Microchip PICmicro microcontroller

devices and many of the Microchip memory parts.

PRO MATE II may be used with MPLAB IDE running under supported Windows

OS's (see Read me for PRO MATE II.txt for support list), with the command-line

controller PROCMD or as a stand-alone programmer

COMPILER-HIGH TECH C

A program written in the high level language called C; which will be converted

into PICmicro MCU machine code by a compiler. Machine code is suitable for use

by a PICmicro MCU or Microchip development system product like MPLAB IDE.

77

PIC START PLUS PROGRAMMER:

The PIC start plus development system from microchip technology

provides the product development engineer with a highly flexible low cost

microcontroller design tool set for all microchip PIC micro devices. The pic start

plus development system includes PIC start plus development programmer and

MPLAB IDE.

The PIC start plus programmer gives the product developer ability to

program user software in to any of the supported microcontrollers. The PIC start

plus software running under MPLAB provides for full interactive control over the

programmer.

ADVANTAGES

LOW COST

RELIABILITY

EASY TO IMPLEMENTATION

APPLICATION

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CONCLUSION

The progress in science & technology is a non-stop process. New things and new technology

are being invented. As the technology grows day by day, we can imagine about the future in

which thing we may occupy every place.

The proposed system based on Atmel microcontroller is found to be more

compact, user friendly and less complex, which can readily be used in order to

perform. Several tedious and repetitive tasks. Though it is designed keeping in

mind about the need for industry, it can extended for other purposes such as

commercial & research applications. Due to the probability of high technology

(Atmel microcontroller) used this” AN INTEGRATED FOUR-PORT DC/DC

CONVERTERFOR RENEWABLE ENERGY APPLICATIONS” is fully

software controlled with less hardware circuit. The feature makes this system is the

base for future systems.

The principle of the development of science is that “nothing is impossible”. So we

shall look forward to a bright & sophisticated world

REFERENCE

MILL MAN J and HAWKIES C.C. “INTEGRATED

ELECTRONICS” MCGRAW HILL, 1972

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ROY CHOUDHURY D, SHAIL JAIN, “ LINEAR INTEGRATED

CIRCUIT”, New Age International Publishers, New Delhi,2000

“THE 8051 MICROCONTROLLER AND EMBEDDED SYSTEM”

by Mohammad Ali Mazidi.

WEBSITES:

http://www.atmel.com/

http://www.microchip.com/

www.8052.com

http://www.beyondlogic.org

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http://www.ctv.es/pckits/home.html

http://www.aimglobal.org/

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