COMPUTER BASED SINGLE PHASE INDUCTION MOTOR

START STOP CONTROL

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Guided By:-Guided By:-

Project Report on

COMPUTER BASED SINGLE PHASE INDUCTION MOTOR START STOP CONTROL

PREPARED BY(1)

(2)

(3)

(4)

(5)

GUIDED BY

CERTIFICATE

This is to certify that Mr.-

of DEE class has satisfactorily completed his term work in PROJECT-1 for the term ending in OCT-NOV. 2015 . DATE:-

Staff-in-charge Head of department

Under DEFINED PROBLEM/PROJECT (UDP) STATEMENT FORMSTUDENT PARTICULARS

FIRST NAMELAST NAMEMOBILE NO.

1.

2.

EMAIL

COLLEGE NAME

A.V PAREKH TECHNICAL INSTITUTE

ADDRESS

A.V PAREKH TECHNICAL INSTITUTETAGOR ROAD OPP.HEMU GADHVI HALLRAJKOT

BRANCH D.E.E.SEMESTER

5th YEAR

2015

ACKNOWLEDGEMENT

I take this opportunity to express my heartfelt gratitude towards “A.V. PAREKH INSTITUTE” that has given me an opportunity to develop this PROJECT.

In particular, I thank the Institute for comments on various aspects of this draft and it’s thoughtful contributions to my effort.Without its support and co-operation I would not have complete my PROJECT work. Also thanking my colleagues, for their help in putting this document together.

I would like to thank my Brother & all my TEACHERS who have played important role in making this project.

Under these responsible & talented personalities I am able to complete my PROJECT report “COMPUTER BASED SINGLE PHASE INDUCTION MOTOR START STOP CONTROL” in time with success.

PREFACE

We are glad to prepare a Project on COMPUTER BASED SINGLE PHASE INDUCTION MOTOR START STOP CONTROLThis report is enriched with sufficien explanation of each point. I am sure that the material given here will undoubtedly be to much use to the students to attain through concrete knowledge of the subject under reference.Enough care has been taken to; make this report flawless. However, Constructive criticism and suggestions from the readers of the report will be greatly accepted.

ABSTRACT

Speed of a DC motor varies proportional to the input voltage. With a fixed supply voltage the speed of the motor can be changed by switching the supply on and off so frequently that the motor notices only the average voltage effect and not the switching operation. This thesis focuses on controlling the speed of a DC motor using PWM technique (varying duty cycle of a square wave) and Data Acquisition Systems.

Sr. No. Contents Page no.

1. Introduction 08

2. Block Diagram 12

3. Circuit diagram 13

4. PCB Layout 14

5. Components list 16

6. List of material 17

7. Working of components 18

8. Explanation of circuit diagram 29

9. Project Model 32

10. Advantages and Applications 33

11. Bibliography 34

Introduction

This project can be used for the controlling of various appliances using PC. It consist a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with the given software can be used with the printer port of any PC for controlling up to eight equipment. Parallel port is a simple and inexpensive tool for building computer controlled devices and projects. The simplicity and ease of programming makes parallel port popular.

Our project “PC Based Switching” is divided in two parts first is hardware & other is software. Hardware part is further divided into three parts, first is power supply, and second is Relay Control circuit and the third is Relay Switch board.

Scope of Project

This project can be used in industries as well as in houses to control the various appliances through PC. Devices can be controlled from the desktop while working on it.

Power Supply

REGULATOR IC (78XX)

It is a three pin IC used as a voltage regulator. It converts unregulated DC current into regulated DC current.

BRIDGE RECTIFIER

A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. This is a widely used configuration, both with individual diodes wired as shown and with single component bridges where the diode bridge is wired internally.

CIRCUIT DIAGRAM OF POWER SUPPLY

Block Diagram

As described in introduction, Hardware is divided in three parts.

1. Power Supply – A 12 volt power supply is used to provide supply to the relay control circuit as well as 12 volt relays.

2. Relay Control Circuit – Relay control circuit mainly includes resistors, Optocouplers and ULN2803 which is already describes previously.

3. Realy Switch Board – Relay Switch Board includes 8 realys which is capable of switching 8 devices according to the signal from parallel port generated through PC

Computer(Parallel Port)

Relay Control Circuit

Power Supply

Relay Switch Board

Single Phase Motor

Power Supply

Circuit Diagram

PCB LAYOUT

BOTTOM VIEW

TOP VIEW

Components Description

Resistors

A resistor is a two-terminal electronic component that produces a voltage across its terminals that is proportional to the electric current through it in accordance with Ohm's law:

V = IR

Resistors are elements of electrical networks and electronic circuits and are ubiquitous in most electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel/chrome).

The primary characteristics of a resistor are the resistance, the tolerance, maximum working voltage and the power rating. Other characteristics include temperature coefficient, noise, and inductance. Less well-known is critical resistance, the value below which power dissipation limits the maximum permitted current flow, and above which the limit is applied voltage. Critical resistance depends upon the materials constituting the resistor as well as its physical dimensions; it's determined by design.

Resistors can be integrated into hybrid and printed circuits, as well as integrated circuits. Size, and position of leads (or terminals) are relevant to equipment designers; resistors must be physically large enough not to overheat when dissipating their power.

Capacitors

A capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors.

An ideal capacitor is characterized by a single constant value, capacitance, which is measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. In practice, the dielectric between the plates passes a small amount of leakage current. The conductors and leads introduce an equivalent series resistance and the dielectric has an electric field strength limit resulting in a breakdown voltage.

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing alternating current to pass, to filter out interference, to smooth the output of power supplies, and for many other purposes. They are used in resonant circuits in radio frequency equipment to select particular frequencies from a signal with many frequencies.

3.4.3 Diode:-

Diodes are two terminal components used to block current in one direction while passing current in the opposite direction. This effect, which converts AC (alternating current) to DC (direct current) is also called "rectifying" current, hence diodes are also called "rectifiers".

The symbol for diode is an arrow and line, indicating passing electricity in only one direction.

A stripe on the component indicates the "perpendicular line on the schematic.

Diode ratings

Diodes have two important ratings and several more subtle ratings. The most important ratings are:

PIV - peak inverse voltageThis is the voltage above which the diode is likely to be damaged, because it stops blocking the flow of electricity in one direction.

Current rating in amps or milliAmps. This is the amount of current the diode can safely dissipate. It is based upon the physical size of the diode and the amount of heat that the the component can dissipate.

Uses for diodes Conversion of AC into DC (rectification) Blocking inverse polarity pulses from inductive loads (solenoids, motors etc) Reverse polarity protection with batteries Voltage doublers (with AC current) DC to DC conversion logic and switching matrices

3.4.4 – 7805 VOLTAGE RECULATOR :-

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels. 

Pin Description: 

 

Pin No

Function Name

1 Input voltage (5V-18V) Input2 Ground (0V) Ground3 Regulated output; 5V (4.8V-5.2V) Output

3.4.5 – 7812 VOLTAGE RECULATOR :-

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels. 

Pin Description: 

 

Pin No

Function Name

1 Input voltage (5V-25V) Input2 Ground (0V) Ground3 Regulated output; 5V (11.8V-12.2V) Output

TRANSFORMER :-

Ideal transformer circuit diagram

Consider the ideal, lossless, perfectly-coupled transformer shown in the circuit diagram at right having primary and secondary windings with NP and NS turns, respectively.

The ideal transformer induces secondary voltage ES =VS as a proportion of the primary voltage VP = EP and respective winding turns as given by the equation

,

where,

- VP/VS = EP/ES = a is the voltage ratio and NP/NS = a is the winding turns ratio, the value of these ratios being respectively higher and lower than unity for step-down and step-up transformers,[3][4][a][b].- VP designates source impressed voltage,- VS designates output voltage, and,- EP & ES designate respective emf induced voltages.[c]

Any load impedance connected to the ideal transformer's secondary winding causes current to flow without losses from primary to secondary circuits, the resulting input and output apparent power therefore being equal as given by the equation

.

Combining the two equations yields the following ideal transformer identity

.

This formula is a reasonable approximation for the typical commercial transformer, with voltage ratio and winding turns ratio both being inversely proportional to the corresponding current ratio.

The load impedance is defined in terms of secondary circuit voltage and current as follows

.

The apparent impedance of this secondary circuit load referred to the primary winding circuit is governed by a squared turns ratio multiplication factor relationship derived as follows[6][7]

.

Induction law

The transformer is based on two principles: first, that an electric current can produce a magnetic field and second that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil.

Referring to the two figures here, current passing through the primary coil creates a magnetic field. The primary and secondary coils are wrapped around a core of very high magnetic permeability, usually iron,[d] so that most of the magnetic flux passes through both the primary and secondary coils. Any secondary winding connected load causes current and voltage induction from primary to secondary circuits in indicated directions.

Ideal transformer and induction law

The voltage induced across the secondary coil may be calculated from Faraday's law of induction, which states that:

where Vs = Es is the instantaneous voltage, Ns is the number of turns in the secondary coil, and dΦ/dt is the derivative [e] of the magnetic flux Φ through one turn of the coil. If the turns of the coil are oriented perpendicularly to the magnetic field lines, the flux is the product of the magnetic flux density B and the area A through which it cuts. The area is constant, being equal to the cross-sectional area of the transformer core, whereas the magnetic field varies with time according to the excitation of the primary. Since the same magnetic flux passes through both the primary and secondary coils in an ideal transformer,[6] the instantaneous voltage across the primary winding equals

Taking the ratio of the above two equations gives the same voltage ratio and turns ratio relationship shown above, that is,

.

The changing magnetic field induces an emf across each winding.[8] The primary emf, acting as it does in opposition to the primary voltage, is sometimes termed the counter

emf.[9] This is in accordance with Lenz's law, which states that induction of emf always opposes development of any such change in magnetic field.

As still lossless and perfectly-coupled, the transformer still behaves as described above in the ideal transformer.

Polarity

Instrument transformer, with polarity dot and X1 markings on LV side terminal

A dot convention is often used in transformer circuit diagrams, nameplates or terminal markings to define the relative polarity of transformer windings. Positively-increasing instantaneous current entering the primary winding's dot end induces positive polarity voltage at the secondary winding's dot end.[10][11][12][f][g]

ULN2803High voltageHigh Current Darlington Transistor Array

The eight NPN Darlington connected transistors in this family of arrays are ideally suited for interfacing between low logic level digital circuitry (such as TTL, CMOS or PMOS/NMOS) and the higher current/voltage requirements of lamps, relays, printer hammers or other similar loads for a broad range of computer, industrial, and consumer applications. All devices feature open–collector outputs and free wheeling clamp diodes for transient suppression.The ULN2803 is designed to be compatible with standard TTL families while the ULN2804 is optimized for 6 to 15 volt high level CMOS or PMOS

ULN 2803

Relay

A relay is an electrical switch that opens and closes under the control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered to be, in a broad sense, a form of an electrical amplifier.

Here relay is used for the isolation of various heavy appliances to the PC. Since the PC operates on very low current, but the current in various appliances is in Amperes therefore isolation is necessary and relay is required. Here we have used single pole dual through relay for the purpose.

Merits

1. Parallel ports are easy to program and faster compared to the serial ports

2. But in parallel port, all the 8 bits of a byte will be sent to the port at a time and a indication will be sent in another line.

3. There will be some data lines, some control and some handshaking lines in parallel port. If three bytes of data 01000101 10011100 10110011 is to be sent to the port, following figures will explain how they are sent to the serial and parallel ports respectively.

De-Merits

1. But main disadvantage is it needs more number of transmission lines. Because of this reason parallel ports are not used in long distance communications.

2. In serial ports, there will be two data lines: One transmission and one receive line. To send a data in serial port, it has to be sent one bit after another with some extra bits like start bit, stop bit and parity bit to detect errors.

Conclusion

The greatest learning experience in this project comes from the design and construction of “PC Based Appliance Controller” which answer a lot of questions regarding the real implementation of Embedded system, Electro-mechanical relays and Opto-couper, ULN 2803, Parallel Port of PC .During the development of our project we studied and analyzed many real world applicationsof Electronics and Software Engineering. Some of the theoretical knowledge that was inculcated in us within our engineering program, which we have applied practically, are:

1. Use of voltage regulation and filtering in power supply.2. Study of parallel ports.3. Study of C-Language.4. Study of ULN.5. Understanding of single pole dual through relay.6. Study of Optocoupler.

References

www.efymag.com

www.projectguidance.com

www.google.com

www.wikipedia.com