1.Modelimi i Ngasjes Dhe Motorit Asinkron- Gjithashtu Edhe Modeli Matematik

7/13/2019 1.Modelimi i Ngasjes Dhe Motorit Asinkron- Gjithashtu Edhe Modeli Matematik

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GENETIC ALGORITHM BASED SIMULATION OF INDUCTION MOTOR DRIVE 2013

Jntuh College Of Engineering Hyderabad Page 1

SPEED CONTROLLER OF INDUCTION MOTOR

USING GENETIC ALGORITHMS

A Thesis

Submitted in partial fulfillment of the

Requirements for the award of the Degree of

MASTER OF TECHNOLOGY

In

ELECTRICAL AND ELECTRONICS ENGINEERING

(POWER ELECTRONICS ENGINEERING)

By

D. NAGESWARA RAO

11011D4318

Under the esteemed guidance of

Dr. A. JAYA LAXMI

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

COLLEGE OF ENGINEERING

(AUTONOMOUS)

HYDERABAD 500085

ANDHRA PRADESH

Year 2011 - 2013


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JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

COLLEGE OF ENGINEERING

(AUTONOMOUS)

HYDERABAD 500 085

ELECTRICAL AND ELECTRONICS ENGINEERING

CERTIFICATE

Certified that this is a bonafide record of the dissertation work entitled, SPEED CONTROLLER OF

INDUCTION MOTOR USING GENETIC ALGORITHM, done by D. NAGESWARA RAObearing Admn.

No: 11011D4318 submitted to the Faculty of Electrical Engineering,in partial fulfillmentof therequirements

for the Degree of MASTER OF TECHNOLOGY with specialization in POWER ELECTRONICS

ENGINEERING from Jawaharlal Nehru Technological University Hyderabad, College of Engineering

(Autonomous), Hyderabad.

Signature of the Head of the Department

Dr. M. SUSHAMAM Tech, Ph.D(JNTUH),M.I.S.T.E

M.S.S.I,M.I.E.T.E

Professor & Head, JNTUCEH

Signature of the Supervisor

Dr. A. JAYA LAXMIM. Tech, Ph. D, M.I.E,M.I.S.T.E

Professor


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ABSTRACT

In the power system, some things like testing process, operator training, apparatus modeling, costly

failures, integrating a subsystem into the system without any fault are some of the concerns of engineers that

can be harmful and cost effective. Research on high level modeling, new converter-inverter topologies and

control strategies are the major research areas in electrical drives. So according to expressed problems there are

some rational reasons for creating digital control on electrical machines and drives. A particular merit of this

approach is that it even permits a gradual change from simulation to actual application, as it allows to start from

a pure simulation and to gradually integrate real electrical and mechanical subsystems into the loop as they

become available. A simulation can help reduce development cycles, cut overall cost, prevent costly failures,

increase repeatability through controlled environment and test a subsystem exhaustively before integrating it

into the system.

Today, it is more common to test controllers using simulated motor models in a real-time environment.

This methodology offers several distinct advantages. For example, the simulated motor drive can be tested with

borderline conditions that would damage a real motor, often a costly prototype. While testing, a controller is

interfaced with the real-time simulated motor drive through a set of proper I/Os. Such motor drive simulation is

required for motor drive manufacturers to accelerate development and testing time, by using real-time

simulation before making tests on physical prototypes.

The project involves Simulation of Induction Motor drive Using Genetic Algorithms with compared

Artificial Intelligence Techniques Such as Fuzzy and Adaptive Neuro-Fuzzy Inference System (ANFIS).

The dissertation work entries the following:

(a) Mathematical modeling and Simulation of Induction Machine Drives with conventional controller

using MATLAB/SIMULINK.

(b) Static and Dynamic Analysis of Induction Motor, using conventional controller.

(c) Implementation of simulation of Induction Machine drives using speed controlled of induction motor

using genetic algorithms, fuzzy, ANFISN are presented in this thesis.

(d) Comparison of dynamic performance of induction motor drive using artificial intelligence controller

such as fuzzy, ANFIS, genetic algorithm.


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ACKNOWLEDGEMENT

I owe a great many thanks to great peoples who helped and supported me during the project. This

acknowledgement is not just a position of words but also an account of confession.

I would like to express my deepest respect and sincere gratitude to my supervisor, Dr. A Jaya Lakshmi for

guiding and correcting various documents of mine with attention and care.

I wish to express my sincere gratitude to Dr. M. SUSHAMA Professor and Head of electrical and electronic

engineering College of JNTUHfor providing me an opportunity to do my project work.

I thank Mr. Prashant Menghalone of my best friends for sharing his valuable time and for giving me helpfulinformation to finish this project. Thank you.

Last but not least I wish to avail myself of this opportunity, express a sense of gratitude towards my parents for

their kind co-operation and encouragement which helped me in completion of this project. I don't always show

it but they know that I do appreciate how much the both of them have helped me with my life, and given me all

of the things that have gotten me here. Thank you Mom and Dad.

D.NAGESWARA RAO


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D. NAGESWARA RAO

Contents

CHAPTER ONE ........................................................................................................................................................ 11

INTRODUCTIONTOINDUCTIONMOTOR DRIVES ....................................................................................................11

1.1 INTRODUCTION OF INDUCTION MOTOR DRIVE................................................................................................................. 121.2 SYNCHRONOUS SPEED ............................................................................................................................................................... 121.3 SLIP ..................................................................................................................................................................................................... 14

1.4 TORQUE CURVE ............................................................................................................................................................................. 14

1.4.1 LOCKED ROTOR TORQUE ...................................................................................................................................................... 15

1.4.2 PULL-UP TORQUE ...................................................................................................................................................................... 15

1.4.3 BREAKE-DOWN TORQUE ........................................................................................................................................................ 15

1.4.4 FULL-LOAD TORQUE ............................................................................................................................................................... 15

1.5 OBJECTIVES ..................................................................................................................................................................................... 16

1.6 CHAPTER BREAK UP ..................................................................................................................................................................... 16

1.7 SPEED CONTROL METHOD .......................................................................................................................................................... 17

A) POLE CHANGING METHOD ......................................................................................................................................................... 17

B) STATOR VOLTAGE CONTROL ..................................................................................................................................................... 19

C) VARIABLE FREQUENCY CONTROL .......................................................................................................................................... 20

D) EDDY CURRENT CONTROL .......................................................................................................................................................... 21

E) ROTOR RESISITANCE CONTROL ................................................................................................................................................ 21

F) SLIP ENERGY RECOVERY SCHEME .......................................................................................................................................... 221.8CONCLUSION .................................................................................................................................................................23

CHAPTER TWO ...................................................................................................................................................... 24

DYNAMICMODELLING&SIMULATIONOFINDUCTIONMOTORDRIVES.........................................................24

2.1DYNAMICMODELLINGOFINDUCTIONMOTOR...............................................................................................25

2.2 DYNAMIC MODEL OF INDUCTION MOTOR .......................................................................................................................... 26

2.3 INDUCTION MOTOR INDUCTANCE MATRIX CALCULATION .......................................................................................... 27

2.4 PARKS TRANSFORMATION........................................................................................................................................................ 30

2.5 INDUCTION MOTOR TORQUE CALCULATION ...................................................................................................................... 30

2.6 INDUCTION MOTOR CURRENT CALCULATION ................................................................................................................... 31

2.7 INDUCTION MOTOR ROTOR SPEED .......................................................................................................................................... 33

2.8 SIMULATION OF A THREE-PHASE INDUCTION MOTOR USING MATLAB-SIMULINK .............................................. 33

2.8.1 AC SOURCE .................................................................................................................................................................................. 35

2.8.2 ABC TO DQ0 PARKS TRANSFORMATION .......................................................................................................................... 36

2.8.3 INDUCTION MOTOR IN D-Q MODEL .................................................................................................................................... 37

2.8.4 STATOR FLUX LINKAGE CALCULATION IN Q-AXIS ....................................................................................................... 37

2.8.5 ROTOR FLUX LINKAGE CALCULATION IN Q-AXIS ........................................................................................................ 38

2.8.6 STATOR FLUX LINKAGE CALCULATION IN D-AXIS ....................................................................................................... 38

2.8.7 ROTOR FLUX LINKAGE CALCULATION IN D-AXIS ........................................................................................................ 39

2.8.8 STATOR CURRENT CALCULATION IN Q-AXIS................................................................................................................. 39

2.8.9 ROTOR CURRENT CALCULATION IN Q-AXIS .................................................................................................................. 40

2.8.10 MUTUAL FLUX LINKAGE CALCULATION IN Q-AXIS .................................................................................................. 40

2.8.11 ROTOR CURRENT CALCULATION IN D-AXIS .................................................................................................................. 41


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2.8.12 STATOR CURRENT CALCULATION IN D-AXIS ............................................................................................................... 41

2.8.13 MUTUAL FLUX LINKAGE CALCULATION IN D-AXIS .................................................................................................. 42

2.8.14 ELECTRICAL TORQUE CALCULATION ............................................................................................................................ 42

2.8.15 ROTOR SPEED CALCULATION ............................................................................................................................................ 43

2.8.16 INVERSE PARKS TRANSFORMATION .............................................................................................................................. 43

2.9 DISCUSSION AND SIMULATION RESULTS ........................................................................................................................... 44

CHAPTER THREE .................................................................................................................................................. 46

SPEEDCONTROLLEROFINDUCTIONMOTORUSINGARTIFICIALINTELLIGENCETECHNIQUES .............46

3.1 INTRODUCTION ............................................................................................................................................................................. 47

3.2 FUZZY LOGIC CONTROLLER IN SIMULINK .......................................................................................................................... 47

3.3 SPEED CONTROLLER .................................................................................................................................................................... 50

3.4 PWM INVERTER ............................................................................................................................................................................. 51

3.5 PWM OUTPUTS ................................................................................................................................................................................ 52

3.6 FLOW CHART OF FUZZY CONTROLLER ................................................................................................................................. 533.7 SIMULATION RESULTS AND DISCUSSIONS .......................................................................................................................... 543.8 INTRODUCTION TO ANFIS .......................................................................................................................................................... 55

3.9 OVERVIEW OF ANFIS .................................................................................................................................................................... 57

3.10 SIMULATION MODEL OF ANFIS .............................................................................................................................................. 58

3.11 SIMULATION RESULTS AND DISCUSSION ........................................................................................................................... 61

CHAPTER FOUR ..................................................................................................................................................... 62

OPTIMIZATIONTECHNIQUES&GENETICALGORITHMS ........................................................................................62

4.1 OPTIMIZATION ................................................................................................................................................................................ 63

4.2 TRADITIONAL METHODS OF OPTIMIZATION ....................................................................................................................... 63

4.3 NON TRADITIONAL METHODS OF OPTIMIZATION ............................................................................................................. 644.4 HISTORY OF GENETIC ALGORITHMS ...................................................................................................................................... 67

4.5 FUNCTIONING OF GENETIC ALGORITHMS ............................................................................................................................ 68

4.6 GENETIC PARAMETERS ............................................................................................................................................................... 71

4.7BASICOPERATIONANDSTAGESINTYPICGENETICALGORITHMS ...........................................................72

4.7.1 SELECTION ................................................................................................................................................................................... 72

4.7.2 CROSS OVER ................................................................................................................................................................................ 76

4.7.3 MUTATION .................................................................................................................................................................................... 79

4.8 STAGES IN GENETIC ALGORITHMS ........................................................................................................................................ 80

4.9 STEPS IN GENETIC ALGORITHMS ............................................................................................................................................. 82

4.10 WHEN IN USE GENETIC ALGORITHMS .................................................................................................................................. 83

4.11 GENETIC ALGORITHMS APPLICATIONS ............................................................................................................................... 84

4.12 ADVANTAGES OF GENETIC ALGORITHMS .......................................................................................................................... 854.13 APPLICATION OF GENETIC ALGORITHMS TO HYBRID SYSTEMS .............................................................................. 85

CHAPTER FIVE ....................................................................................................................................................... 87

GENETCALGORITHMBASEDSIMULATIONOFINDUCTIONMOTORDRIVE.....................................................87

5.1 SIMULATION OF GA BASED INDUCTION MOTOR DRIVE ................................................................................................ 87

5.2 SIMULATION RESULTS AND DISCUSSION WITH GA BASED FUZZY CONTROLLER .............................................. 89

5.3 SIMULATION RESULTS AND DISCUSSION WITH GA,ANFIS,FUZZY ............................................................................. 90

5.4 COMPARATIVE APPROACH TO DIFFERENT AI BASED SIMULATION OF INDUCTION MOTOR ............................ 91

5.5 CONTINUOS GENETIC ALGORITHM MATLAB CODE APPIXA ....................................................................................... 95

5.6 TEST FUNCTION MATLAB CODEAPPIXB ........................................................................................................................... 97


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5.7 CONCLUSION .................................................................................................................................................................................. 97

5.8 THE SCOPE OF THE FUTURE WORKS ...................................................................................................................................... 97

APPENDIXC ............................................................................................................................................................................98REFERENCE..............................................................................................................................................................................99

Figures

CHAPTER ONE ........................................................................................................................................................ 11

INTRODUCTIONTOINDUCTIONMOTORDRIVES .....................................................................................................11Fig. 1.1 Conceptual diagram of an induction machine ......................................................................................................................... 13

Fig. 1.2 Conventional per-phase equivalent circuit .............................................................................................................................. 13

Fig. 1.3 Torque speed curve ................................................................................................................................................................. 15

Fig. 1.4 Static and dynamic inductance definitions .............................................................................................................................. 16

Fig. 1.5 Stator phase connections for six poles ...................................................................................................................................... 18

Fig. 1.6 Speed-Torque curves ................................................................................................................................................................. 18

Fig. 1.7 Torque-speed curves at various voltages ................................................................................................................................. 19

Fig. 1.8 Torque-Speed characteristics for variable frequency control ................................................................................................. 20

Fig. 1.9 Slip ring induction motor with external rotor resistors ............................................................................................................ 21

Fig. 1.10 Torque versus speed at various rotor resistances ................................................................................................................... 22

Fig. 1.11 Static Kramer method .............................................................................................................................................................. 23

CHAPTER TWO ...................................................................................................................................................... 24

DYNAMICMODELLING&SIMULATIONOFINDUCTIONMOTORDRIVE ...........................................................24

Fig. 2.1 The d-q equivalent circuit of an induction motor ..................................................................................................................... 25

Fig. 2.2 Definition of d-axis and q-axis on an arbitrary reference frame ............................................................................................. 26

Fig. 2.3 Principle of the control system .................................................................................................................................................. 34

Fig. 2.4 Induction model with conventional controller ......................................................................................................................... 34

Fig. 2.5 AC source of main model ......................................................................................................................................................... 36

Fig. 2.6 abc to DQ0 Parks transformation model ................................................................................................................................. 36

Fig. 2.7 Induction motor in d-q model ................................................................................................................................................... 37

Fig. 2.8 Flux linkage calculation model overall view ........................................................................................................................... 37

Fig. 2.9 Stator flux linkage calculation in q-axis .................................................................................................................................. 38

Fig. 2.10 Rotor flux linkage calculation in q-axis ................................................................................................................................. 38Fig. 2.11 Stator flux linkage calculation in d-axis ................................................................................................................................. 39

Fig. 2.12 Rotor flux linkage calculation in d-axis ................................................................................................................................. 39

Fig. 2.13 Stator, rotor and mutual flux linkage calculation in q-axes ................................................................................................... 40

Fig. 2.14 Stator current calculation in the q-axis ................................................................................................................................... 40

Fig. 2.15 Rotor current calculation in the q-axis ................................................................................................................................... 40

Fig. 2.16 Mutual flux linkage calculation in the q-axis ........................................................................................................................ 41

Fig. 2.17 Stator, rotor and mutual flux linkage calculation in the d-axis ............................................................................................. 41

Fig. 2.18 Rotor current calculation in the d-axis ................................................................................................................................... 41

Fig. 2.19 Stator current calculation in the d-axis ................................................................................................................................... 42

Fig. 2.20 Mutual flux linkage calculation in the d-axis ......................................................................................................................... 42

Fig. 2.21 Electrical Torque calculation ................................................................................................................................................... 43


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Fig. 2.22 Rotor speed calculation ........................................................................................................................................................... 43

Fig. 2.23 D-Q to abc inverse Parks transformer produce rotor and stator currents ............................................................................ 44

Fig. 2.24 Torque result from conventional simulation ......................................................................................................................... 45

Fig. 2.25 Speed result from conventional simulation ........................................................................................................................... 45

Fig. 2.26 Stator current result from conventional simulation ............................................................................................................... 45

Fig. 2.27 Rotor current result from conventional simulation ............................................................................................................... 45

CHAPTER THREE ..................................................................................................................................................... 46

SPEEDCONTROLLEROFINDUCTIONMOTORUSINGARTIFICIALINTELLIGENCETECHNIQUES .............46

Fig. 3.1 Overall view of Fuzzy-logic based controller .......................................................................................................................... 47

Fig. 3.2 The Fuzzy Controller model ...................................................................................................................................................... 49

Fig. 3.3 Controllable frequency sin wave generator ............................................................................................................................. 50

Fig. 3.4 Speed control model .................................................................................................................................................................. 50

Fig. 3.5 PWM inverter circuit ................................................................................................................................................................ 51

Fig. 3.6 Outage block .............................................................................................................................................................................. 52

Fig. 3.7 IGBTs gating signals ................................................................................................................................................................. 52Fig. 5.8 PWM inverter output ................................................................................................................................................................ 52

Fig. 3.9 Simulation process flow chart ................................................................................................................................................... 53

Fig. 3.10 Speed response with fuzzy ...................................................................................................................................................... 54

Fig. 3.11 Torque response with fuzzy ..................................................................................................................................................... 54

Fig. 3.12 Stator currents with fuzzy ........................................................................................................................................................ 54

Fig. 3.13 Rotor currents with fuzzy ........................................................................................................................................................ 54

Fig. 3.14 ANFIS architecture ................................................................................................................................................................. 57

Fig. 3.15 Overall Neuro-Fuzzy simulation model ................................................................................................................................ 58

Fig. 3.16 Neuro-Fuzzy ............................................................................................................................................................................. 60Fig. 3.17 Speed characteristics with ANFIS .......................................................................................................................................... 61

Fig. 3.18 Torque characteristics with ANFIS ......................................................................................................................................... 61

Fig. 3.19 Stator currents with ANFIS controller .................................................................................................................................. 61

Fig. 3.20 Rotor currents with ANFIS controller .................................................................................................................................. 61

CHAPTER FOUR ........................................................................................................................................................ 62

OPTIMIZATIONTECHNIQUES&GENETICALGORITHMS ........................................................................................62

Fig. 4.1 Block diagram of genetic algorithm ......................................................................................................................................... 70

Fig. 4.2 General scheme of a genetic algorithm .................................................................................................................................... 70

Fig. 4.3 Roulette- wheel selection .......................................................................................................................................................... 74

Fig. 4.4 Rank selection diargam ............................................................................................................................................................. 75

Fig. 4.5 Single point crossover ................................................................................................................................................................ 77

Fig. 4.6 Two point crossover ................................................................................................................................................................... 77

Fig. 4.7 Uniform crossover ...................................................................................................................................................................... 78

Fig. 4.8 Stages in a typical genetic algorithm......................................................................................................................................... 81

Fig. 4.9 Typical genetic algorithm representation .................................................................................................................................. 83

CHAPTER FIVE ......................................................................................................................................................... 87

GENETICALGORITHMSBASEDSIMULATIONOFINDUCTIONMOTORDRIVE ................................................87

Fig. 5.1 speed controller of induction motor with genetic algorithm ..................................................................................................... 88

Fig. 5.2 Speed characristics with GA controller ....................................................................................................................................... 89

Fig. 5.3 Torque characristics with GA controller ..................................................................................................................................... 89

Fig. 5.4 Stator currents with GA controller ............................................................................................................................................. 89

Fig. 5.5 Rotor currents with GA controller .............................................................................................................................................. 89

Fig. 5.6 GA optimization values............................................................................................................................................................... 90

Fig. 5.7 Speed with GA controller ........................................................................................................................................................... 90

Fig. 5.8 Torque with GA controller.......................................................................................................................................................... 90


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Fig. 5.9 Speed with ANFIS controller ..................................................................................................................................................... 91

Fig. 5.10 Torque with ANFIS controller ................................................................................................................................................. 91

Fig. 5.11 Stator current with ANFIS ........................................................................................................................................................ 91

Fig. 5.12 Rotor currents with ANFIS ....................................................................................................................................................... 91

Fig. 5.13 Speed response of conventional controller with fuzzy ........................................................................................................... 92

Fig. 5.14 Speed response of FUZZY controller ...................................................................................................................................... 92

Fig. 5.15 Speed response of ANFIS controller ........................................................................................................................................ 92

Fig. 5.16 Speed with GA controller ......................................................................................................................................................... 92

Fig. 5.17 Torque with GA controller........................................................................................................................................................ 92

Fig. 5.18 Torque response of conventional controller ............................................................................................................................ 93

Fig. 5.19 Torque response of ANFIS ....................................................................................................................................................... 93

Fig. 5.20 Torque response of fuzzy controller........................................................................................................................................ 93

Fig. 5.21 Speed response of GA controller .............................................................................................................................................. 94

Fig. 5.22 Torque response of GA controller ............................................................................................................................................ 94

Tables

Table 4.1 Population and fitness. ............................................................................................................................................................ 75

Table 7.1 Speed comparison between Conventional, Genetic algorithm, fuzzy and ANFIS ............................................................ 93


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GLOSSARY OF SYMBOLS

Rs The stator resistance

Rr The rotor resistance

Lm The magnetizing inductance of the motor

Lls The stator leakage inductance

Llr The rotor leakage inductance

r The slip frequency which is the frequency of the actual rotor current

Llr The rotor leakage inductance referred to stator side

Rr The rotor resistance referred to stator side

qs , ds Q-axis and d-axis components of stator flux

qr , dr Q-axis and d-axis components of rotor flux

iqs , ids Q-axis and d-axis components of stator current

iqr , iqr Q-axis and d-axis components of rotor current

vqs , vds Q-axis and d-axis components of stator voltage

vqr , vqr Q-axis and d-axis components of rotor voltage

p Number of poles

The angular position of the rotor

a Reference frame rotating speed

J Moment of inertia (kg/m2)

Te Electrical torque

Tl Load torque

e (k) Control error

r (k) Reference signal

y (k) Output signal

e(k) Changed error

u(Ri) The crisp u value corresponding to the maximum membership degree


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CHAPTER ONE

INTRODUCTION TO INDUCTION MOTOR DRIVES


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1.1 INTRODUCTION OF INDUCTION MOTOR DRIVE

In the industrial sector especially in the field of electric drives & control, induction motors play a vital role.Without proper controlling of the speed, it is virtually impossible to achieve the desired task for a specific

application. Basically AC motors, such as Induction Motors are of Squirrel-Cage type. They are simple,

reliable, low cost and virtually maintenance-free electrical drives. Based on the inability of conventional control

methods like PI, PID controllers to work under wide range of operation, artificial intelligent based controllers

are widely used in the industry like ANN, Fuzzy controller, ANFIS, expert system, genetic algorithm. The main

problem with the conventional fuzzy controllers is that the parameters associated with the membership

functions and the rules depend broadly on the intuition of the experts. To overcome this problem, GA based

Adaptive Neuro-Fuzzy controller and Fuzzy Logic controller are proposed in this dissertation .

In most of the industries, induction motors play very important and that is the reason they are manufactured inlarge numbers. About half of the electrical energy generated in a developed country is ultimately consumed by

electric motors, of which over 90 % are induction motors. For a relatively long period, induction motors have

mainly been deployed in constant-speed motor drives for general purpose applications. The rapid development

of power electronic devices and converter technologies in the past few decades, however, has made possible

efficient speed control by varying the supply frequency, giving rise to various forms of adjustable-speed

induction motor drives. In about the same period, there were also advances in control methods and Artificial

Intelligence (AI) techniques. Artificial Intelligent techniques mean use of expert system, fuzzy logic, neural

networks and genetic algorithm. Researchers soon realized that the performance of induction motor drives can

be enhanced by adopting artificial-intelligence-based methods. Since the 1990s, AI-based induction motor

drives have received greater attention. Among the existing control technologies, intelligent control methods,

such as fuzzy logic control, neural network control, genetic algorithm, and expert system, have exhibited

particular superiorities. Artificial Intelligent Controller (AIC) could be the best controller for Induction Motor

control. Over the last two decades, researchers have been working to apply AIC for induction motor drives [1-

6]. This is because that AIC possesses advantages as compared to the conventional PI, PID and their adaptive

versions. Since the unknown and unavoidable parameter variations, due to disturbances, saturation and change

in temperature exists; it is often difficult to develop an accurate system mathematical model. High accuracy is

not usually of high importance for most of the induction motor drive. During the operation, even when the

parameters and load of the motor varies, a desirable control performance in both transient and steady states must

be provided. Controllers with fixed parameters cannot provide these requirements unless unrealistically high

gains are used. Therefore, control strategy must be robust and adaptive. As a result, several control strategies

have been developed for induction motor drives within last two decades. The main idea for such a hybrid

controller is that with a combination of fuzzy logic and neural network, such as uncertainty or unknown

variations in plant parameters and structure can be dealt more effectively. Hence, the robustness of the control

of induction motor is improved. Conventional controllers have on their side well established theoretical

backgrounds on stability and allow different design objectives such as steady state and transient characteristics

of the closed loop system to be specified. Much research work is in progress in the design of such hybrid

control schemes. Fuzzy controller conventionally is totally dependent to memberships and rules, which are

based broadly on the intuition of the designer.


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The induction motor, which is the most widely used motor type in the industry, has been favored

because of its good self-starting capability, simple and rugged structure, low cost and reliability, etc. Along with

variable frequency AC inverters, induction motors are used in many adjustable speed applications which do not

require fast dynamic response.

In induction and synchronous motors, the stator is powered with alternating current (poly phase

current in large machines) and designed to create a rotating magnetic field which rotates in time with the AC

oscillations. In a synchronous motor, the rotor turns at the same rate as the stator field. By contrast, in an

induction motor the rotor rotates at a slower speed than the stator field. Therefore the magnetic field through the

rotor is changing (rotating). The rotor has windings in the form of closed loops of wire. The changing magnetic

flux induces currents in the windings as in a transformer, and these currents create their own magnetic fields.

These interact with the stator field to create torque to turn the rotor.

For these currents to be induced, the speed of the physical rotor must be lower than that of the stator's

rotating magnetic field (ns), or the magnetic field would not be moving relative to the rotor conductors and no

currents would be induced. As the speed of the rotor drops below synchronous speed, the rotation rate of the

magnetic field in the rotor increases, inducing more current in the windings and creating more torque. The ratio

between the rotation rate of the magnetic field as seen by the rotor (slip speed) and the rotation rate of the

stator's rotating field is called "slip". Under load, the speed drops and the slip increases enough to create

sufficient torque to turn the load. For this reason, induction motors are sometimes referred to as asynchronous

motors.

1.2 SYNCHRONOUS SPEED

The synchronous speedof an AC motor is the rotation rate of the rotating magnetic field created by the

stator. It is always an integer fraction of the supply frequency. The synchronous speed nsin revolutions per

minute (rpm) is given by:

= 60 wherefis the frequency of the AC supply current in Hz andpis the number of magnetic pole pairs per

phase. For example, a small 3-phase motor typically has six magnetic poles organized as three opposing pairs

120 apart, each powered by one phase of the supply current, so there is one pole pair per phase andp= 1. For

60 Hz supply frequency, its synchronous speed is thus 3600 RPM. Under no-load conditions, when the only

load on the motor is its friction, the speed approaches synchronous speed.


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The concept of vector control has opened up a new possibility that induction motors can be controlled to

achieve dynamic performance as good as that of DC or brushless DC motors.

In order to understand and analyze vector control, the dynamic model of the induction motor is

necessary. In this project as a first step, an induction motor model is derived in relatively simple terms by using

the concept of space vectors and d-q variables.

Fig. 1.1 Conceptual diagram of an induction machine.

Traditionally in analysis and design of induction motors, the per-phase equivalent circuit of induction

motors shown in Fig. 1.1 has been widely used. In the circuit note that all rotor parameters and variables are not

actual quantities but are quantities referred to the stator, parameters are defined by:

Ls Lsr Rrs

Fig. 1.2 Conventional per-phase equivalent circuit

Rs: stator resistance

Rr: rotor resistance


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Lm: magnetizing inductance of the motor

Ls: stator inductance

Lr: rotor inductance

Lrs: rotor inductance referred to the stato

It is also known that induction motors do not rotate synchronously to the excitation frequency. At rated load, the

speed of induction motors are slightly less than the synchronous speed.

1.3 SLIP

Slip sis the ratio of the rotation rate of the rotor magnetic field to the rotation rate of the stator magnetic

field.

= N NN Where nris the rotor rotation speed in rpm. It is zero at synchronous speed and one (100%) when the rotor isstationary. The slip determines the motor's torque. Since the short-circuited rotor windings have small

resistance, a small slip induces a large current in the rotor and produces large torque.

1.4 TORQUE CURVE

The torque exerted by the motor as a function of slip is given by a torque curve. Over a motor's normal

load range, the torque line is close to a straight line, so the torque is proportional to slip. As the load increases

above the rated load, increases in slip provide less additional torque, so the torque line begins to curve over.

Finally at a slip of around 20% the motor reaches its maximum torque, called the "breakdown torque". If the

load torque reaches this value, the motor will stall. At values of slip above this, the torque decreases. In 3-phase

motors the torque drops but still remains high at a slip of 100% (stationary rotor), so these motors are self-

starting. The starting torque of an induction motor is less than other types of motor, but still around 300% of

rated torque. In 2-pole single-phase motors, the torque goes to zero at 100% slip (zero speed), so these require

alterations to the stator such as shaded poles to provide starting torque.


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Fig. 1.3 Torque speed curve1.4.1 LOCKED ROTOR TORQUE: The minimum torque that a motor will develop at rest for all angular

positions of the rotor is called locked rotor torque or starting torque.

1.4.2PULL-UP TORQUE: The minimum torque delivered by an AC motor during the period of acceleration

from zero to the speed at which breakdown occurs.

1.4.3BREAK-DOWN TORQUE: Itis the point at which an excessive load on the motor will cause it to stop.

1.4.4FULL-LOAD TORQUE: The torque a motor produces at its rated horsepower and full-load speed.

As I said r is called the slip frequency which is the frequency of the actual rotor current. In the steady-

state AC circuit, current and voltage phasors are used and they are denoted by the overline. In Fig. 1.2, power

consumption in the stator is interpreted as Is2Rs, while Ir 2Rrs represents both power consumption in the rotor

and the mechanical output (torque). By subtracting rotor loss Ir 2Rr from Ir 2Rrs, produced torque (mechanical

power divided by the shaft speed) is given by:

= By definition, two kinds of analysis of induction motors are considered in the literature:

1) The static inductance: that the slope of the straight line (OA) from the origin through the actual

operating point A on the magnetizing curve Fig. 1.4. The static inductance is therefore the division of


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the flux by the magnetizing current.This value is used for steady state condition or when operation of

the machine changes from one to another steady state situation and the transients are not so important.

Static inductance

Fig. 1.4 static and dynamic inductance definitions

2) The dynamic inductance:that the slope of the tangent line (AC), to the magnetizing curve at the same

operating point A, as represented in Fig. 1.4.

1.5 OBJECTIVES

Induction Motors have many applications in the industries, because of the low maintenance and

robustness. The speed control of induction motor is more important to achieve maximum torque and efficiency.

This thesis presents an integrated environment for speed control of induction motor (IM) including simulation.The integrated environment allows users to compare simulation results between classical and genetic algorithm

controllers i.e. Fuzzy and ANFIS. It is due to its unique characteristics like high efficiency, good power factor

and extremely rugged nature of Induction motor. The genetic algorithm and fuzzy logic controller and artificial

neuro-fuzzy controllers are also introduced to the system for keeping the motor speed to be constant. The

performance of genetic algorithm and fuzzy logic and artificial neuro-fuzzy based controllers is compared with

that of the conventional proportional integral controller. The dynamic modeling of Induction motor is done and

the performance of the Induction motor drive has been analyzed.

1.6 CHAPER BREAK UP

In the first chapter the basic knowledge required to understand the Induction motor operation is briefly

covered.

In the second chapter the dynamic model of Induction motor is fully formulated and its mathematical

equations are clearly proven.

At the third chapter the different techniques to control the induction motor speed is briefly listed and

then explained.

= Dynamic inductance

=


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At the fourth chapter the dynamic simulation of induction motor drive according to the model expressed

in chapter two is done and each and every part is separately explained and executed.

The fifth chapter will discuss how to improve the speed control of induction motor based on genetic

algorithm controller for taking better results compare to dynamic model simulation.

The sixth chapter will discuss how to improve the speed control of fuzzy controller based simulation

with replacing fuzzy controller part with genetic algorithm controller.

At the end the seventh chapter will compare all discussed methods, and find a technique as the best in

this project

.

1.7 SPEED CONTROL METHODSFollowing are the methods employed to control the speed of induction motors.

A) Pole changing.

B) Stator voltage control.

C) Supply frequency control.

D) Eddy-current control.

E) Rotor resistance control.

F) Slip power recovery.

While pole changing is applicable to squirrel cage motors, stator voltage control and supply frequency

control can be used for both squirrel cage and wound rotor motors. Whereas rotor resistance control and slip

power recovery methods are applicable only to wound rotor motors as they are controlled from the rotor circuit.

A) POLE CHANGING METHOD:

For a particular frequency, the synchronous speed is inversely proportional to the number of poles.

Changing the number of poles can change synchronous speed and therefore the motor speed. Provision for

changing the number of poles has to be incorporated at the time of manufacturing stage and such machines are

called, pole-changing motorsor multi-speed motors.

Squirrel cage rotor is not wound for any specific number of poles. It produces the same number of poles

as stator winding has. Therefore, in a squirrel cage motor, an arrangement is required only for changing the

number of poles in stator. In wound rotor motor, arrangement for changing the number of poles in rotor is also

required, which complicates the machine. Therefore, this method of speed control is only used with squirrel

cage motors.


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This method is simple but expensive arrangement for changing the number of stator poles. It uses two

separate windings, which are wound for two different pole numbers. An economical and common alternative is

to use a single stator winding divided into few coil groups, and by rearranging the coil groups we can obtain

different speeds, which are factor of 2. The Fig. 3.1 shows a phase winding which consists of six coils divided

into two groups a-b consisting of odd number coils(1,3,5) connected in series and c-d consisting of even

numbered coils(2,4,6) connected in series which are shown.

Fig. 1.5 Stator phase connections for six poles

The speed-torque curves for 6 pole and 12 pole formation can be shown as in Fig. 3.2.

Fig. 1.6 Speed-Torque curves

In some applications, change in speed is required only by a small amount (for example. fan and pump

drives).Such a small change in speed is possible by pole amplitude modulation. As pole systems are not

alternating along the periphery, these motors in modified connection suffer from harmonic currents and

voltages, and have lower power factor and efficiency than pole changing motors.


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B) STATOR VOLTAGE CONTROL:

By reducing the stator voltage, speed of a high-slip induction motor can be reduced by an amount, which

is sufficient for the speed control. While torque is proportional to square of the voltage, the voltage if reduced

reduces the speed. So for the same current the motor develops lower torque therefore such loads which demand

less torque with the decrease in the speeds are suitable under this control ( fan and pump drives ).

This method of speed control is not suitable for normal mains fed with 3-phase Induction Motor. The

portion of speed torque curve beyond the point of maximum torque is unstable. The normal cage motor has

small resistance and therefore, the unstable portion is large. The speed control is possible only in narrow band

of speeds. The starting current of these motors is also very high. The equipment used to control the speed must

be able to withstand this current. The power factor is poor at large slips. Therefore special rotor design with

high resistance is required to be able to take advantage of speed control by voltage variation. The Fig. 3.3 shows

the Torque-Speed curves of an Induction motor at various voltages assuming sinusoidal voltage.

This method is very simple but speed control range is very much limited. Speed range can be made

wider if the rotor resistance is larger. The line p.f is poor. The line and motor currents have harmonic content.

Fig. 1.7 Torque-speed curves at various voltages

Machine has poor efficiency, heating of motor is more, and regeneration is not possible. It is used with

fan loads, blowers and pumps.


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C) VARIABLE FREQUENCY CONTROL(V/F):

Synchronous speed P

f

Ns 120

..(3.1)

And, motor speed, sr NsN 1 (3.2) check

eqn no

From the above it is evident that synchronous speed is directly proportional to the supply frequency.

Therefore, by varying supply frequency we can control the speed of the induction motor. Motor speed can be

controlled below and above the synchronous speed. Voltage induced in stator is proportional to the product of

supply frequency and air gap flux. If stator drop is neglected, terminal voltage can be considered proportional to

the product of frequency and flux. The equations 3.3 and 3.4 justify the above statements.

pssmw Tfk.E 444 (3.3)

pssmw Tfk.V 444 ...(3.4)

While any increase in flux beyond the rated value is undesirable from the consideration of saturation

effects a decrease in flux is also avoided to retain the torque capability of motor. Therefore, the variable

frequency control below the rated frequency is generally carried out by reduced machine phase voltage along

with the frequency; the motor is operated at a constant voltage because of limitations imposed by stator

insulation or supply voltage limitations.

The motor is always operated on the portion of the speed torque curves with a negative slope, by

limiting either the slip speed or the current for getting the advantages of the high torque to current ratio, high

efficiency and a good power factor.

Fig. 1.8 Torque-Speed characteristics for variable frequency control


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Variable frequency control gives larger torques with reduced currents for the complete range of speeds. This

method provides a highly efficient variable speed drive with excellent running and transient performance.

Regenerative braking is also possible below synchronous speed down to zero speed.

D) EDDY CURRENT CONTROL

Drive consists of an eddy current clutch placed between an induction motor running at a fixed speed and

the variable speed load. Speed is controlled by controlling D.C excitation to magnetic circuit of the clutch.

Since motor runs at a fixed speed, it can be fed directly from AC mains.

E) ROTOR RESISTANCE CONTROL

This method is suitable for wound rotor induction motor. Maximum torque is independent of rotor

resistance, speed at which the maximum torque is produced changes with rotor resistance. For the same torque,

speed falls with an increase in rotor resistance. Advantages of rotor resistance control are that motor torque

capability remains unaltered even at low speeds. Only other method, which has this advantage, is variable

frequency control. This method is used for only low speeds, because of low cost of rotor resistance and high

torque capability at low speeds, and rotor resistance control is employed in cranes, high load drives. A major

disadvantage is low efficiency due to additional losses in resistor connected in the rotor circuit.

Fig. 1.9 Slip ring induction motor with external rotor resistors


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Fig. 1.10 Torque versus speed at various rotor resistances, curves 1, rotor short-circuited; 2-4,

increasing values of external resistance

F) SLIP ENERGY RECOVERY SCHEMEThe portion of air gap power, which is not converted into mechanical power, is called slip power. Slip

control methods regulate the amount of slip power. The slip power is controlled by controlling the voltage

injection into the rotor. By this method induction motor speed can be controlled from speed zero to speed higher

than the synchronous speed. Instead of wasting power in external resistors, it is usefully employed here.

Therefore, these methods of speed control are classified as slip power recovery schemes. The circuital

connections for slip energy recovery scheme and torque speed characteristics can be as shown in the next

Figures.


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Fig. 1.11 Static Kramer method

The main problem in providing suitable source is that the frequency of the injected emf must match the

rotor slip frequency at all speeds. Two such schemes are: static Scherbiusdrives and static Kramer drives which

provides speed control of wound rotor motor below and above synchronous speed respectively.

This speed is suitable for driving high capacity centrifugal pumps and fans. Speed control is achieved from

above synchronous speed to zero speed.

.1.8 CONCLUSION

In this chapter mathematical model of induction motor has been developed for dynamic analysis of the

symmetrical induction machines in the arbitrary reference frame. In chapter Four the block based simulation

will be constructed according to these equations and then will be simulated.


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CHAPTER TWO

DYNAMIC MODELLING & SIMULATION OF INDUCTION MOTORDRIVE


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2.1 DYNAMIC MODELLING OF INDUCTION MOTOR

The voltage and torque equations that describe the dynamic behavior of an induction motor are time-varying. Differential equations involve some complexity. A change of variables can be used to reduce the

complexity of these equations by eliminating all time-varying inductances. By this approach, a poly phase

winding can be reduced to a set of two phase windings (q-d) with their magnetic axis formed in quadrature. In

other words, the stator and rotor variables (voltages, currents and flux linkages) of an induction machine are

transferred to a reference frame, which may rotate at any angular velocity or remain stationary. Such a frame of

reference is commonly known in the generalized machines analysis as arbitrary reference frame.

Fig. 2.1: the d-q equivalent circuit of an induction motor

The dynamic analysis of the symmetrical induction machines in the arbitrary reference frame has been

intensively used as a standard simulation approach from which any particular mode of operation may then bedeveloped. It can be a powerful technique in implementing the machine equations as they are transferred to a

particular reference frame. Thus, every single equation among the model equations can be easily implemented

in one block so that all the machine variables can be made available for control and verification purposes[2-3].

qs (- r) qsRs RrLls= Ls+Lm L'lr= Lr+Lm

Vds Vdrds dr

ds (- r) ds Rr

Vqr

Rs Lls= Ls+Lm Llr= L'r+Lm

Vqsqs qr

Lm

Lm

ids idr

iqs iqr


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2.2 DYNAMIC MODEL OF INDUCTION MOTOR

Before everything, its better to clarify some of the parameters and concepts that are existing in thedynamic model.

Rs: the stator resistance

Rr: the rotor resistance

Lm: the magnetizing inductance of the motor

Lls: the stator leakage inductance

Llr: the rotor leakage inductance

r: the slip frequency which is the frequency of the actual rotor current

Llr: the rotor leakage inductance referred to stator side

Rr: the rotor resistance referred to stator side

qs , ds : q-axis and d-axis components of stator flux

qr , dr: q-axis and d-axis components of rotor flux

iqs , ids: q-axis and d-axis components of stator current

iqr , iqr:q-axis and d-axis components of rotor current

vqs , vds: q-axis and d-axis components of stator voltage

vqr , vqr:q-axis and d-axis components of rotor voltage

Note that in this equivalent circuit, all rotor parameters and variables are not actual quantities but are quantities

referred to the stator. And also we know that induction motors do not rotate synchronously to the excitation

frequency. At rated load, the speed of induction motors are slightly less than the synchronous speed.

Fig. 2.2: d-axis and q-axis on an arbitrary reference frame.


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Let the stator to rotor winding turn ratio be n and the angular position of the rotor be , and definethe

rotor velocity in the form of the following that p is the number of poles.

r=p

Fig. 2.2 illustrates the relationship between d-q axis and complex plane on a rotating frame with respect

to stationary a-b-c frame. Note that d-axes and q-axes are defined on a rotating reference frame at the speed of

awith respect to fixed a-b-c frame.

= a=p a

The generalized equivalent circuit on an arbitrarily rotating frame is shown in Fig. 2.1. Now, depending

on a specific choice of a, many forms of dynamic equivalent circuit can be established. Among them, the

synchronous frame form can be obtained by choosing a= e.

2.3 INDUCTION MOTOR INDUCTANCE MATRIX CALCULATION

The sum of the stator leakage inductance and magnetizing inductance is called the stator inductance (Ls=

Lls+ Lm), and the sum of the rotor leakage inductance and magnetizing inductance is called the rotor inductance

(Lr=Llr+ Lm), where we have the following equations:

= = As we can see in the Fig. 2.1 the rotating emf-es are represented by voltage sources and not by

Inductances. Consequently, rotor appears near to the natural induced voltage, expressed by means of the rotor

speed.

Driving the model equations can be generated from the d-q equivalent circuit of the induction machine

shown in Fig. 2.1. The voltage and current equations associated with this circuit can be found as follows:

The flux linkages can be achieved as follows:

= + .(2.1) = + = + ..(2.2) = + ...........(2.3)

=

+

=

+

......(2.4)


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The voltage equations are as following:

= +

+ .....(2.5) = + ...(2.6) = + + ( ) ....(2.7) = + ( ) ..(2.8)

For obtaining the voltages the following steps have to be done:

By placing the equation 1 and equation 2 into the equation 5, vqs obtained as:

= + + = + + +( +)

=

+

+

+

+

..(2.9)

By placing the equation 1 and equation 2 into the equation 6, vds obtained as:

= + = + ( + )

( +)

= + + (2.10)By placing the equation 2 and equation 3 into the equation 7 , vqr obtained as:

= + + ( )

= + (

+

)

+ ( )( +)


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= +

+

+ ( ) ( ) .(2.11)By placing the equation 1 and equation 4 into the equation 8, vdr obtained as:

= + ( ) = + ( +) ( +)

= + + ( ) ( ).(2.12)According to calculation, for ease of studying equations 2.9,2.10,2.11,2.12 are listed below: = + + + + = + + = + + + ( ) + ( )

=

+

+

(

)

(

)

Vdrand Vqrare short circuited hence they are equal to zero. The electrical transient model in terms of voltages

and currents can be given in matrix form as:

00

= + + ( )( ) + ( )( ) +

In the above matrixprepresents the operator. For stationary reference frame, by substituting = 0, the abovematrix equation is reduced to:

00

= + 00 + 00 ( )( ) + ( )( ) +


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Moreover, for synchronous frame, we have = 0

0 =

+

+

()( ) + ()( ) + Since actual stator variables either to be generated or to be measured are all in stationary a-b-c frame, frame

transform should be executed in the control. The most popular transform is between stationary a-b-c frame

quantities to synchronously rotating d-q quantities.

2.4 PARKS TRANSFORMATION

The following equation shows how a-b-c frame can be transformed into the q-d frame:

0 = cossin cos( 2/ 3) cos( + 2/ 3)sin( 2/ 3) sin( + 2/ 3)

0.5 0.5 0.5

And its inverse transform is given by:

=

coscos(

2

/ 3)

sin 1sin(

2

/ 3) 1

cos(

+ 2

/ 3) sin(

+ 2

/ 3) 1

0

As we have seen the voltage and current in stationary and rotor reference frame in the form of [] = [] []isachieved, where [v] and [i] are 4x1 column matrices of voltage and current and are given as

[ ] and [ ]respectively.2.5 INDUCTION MOTOR TORQUE CALCULATION

The torque equation is:

=3

2 21

(2.13) Which is in the vector form. Equation 2.13 can be rewriten as (Bolded letters shows it is in vector space):=

3

4 1 () ...(2.14)

For calculating the electromagnetic torque, transfer [] = [][]to the stationary reference frame so that the will be equal to zero.then s is kept as superscript which is written as follows:


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[] = [] []Where [

] and [

]are 4x1 column matrices of voltage and current in the stationary frame and are given as

[]and [ ]respectively.So the impedance matrix will be as follows: + 00 + 00 ( )( ) + ( )( ) +

Although the torque expression on the above is derived from stationary reference frame, it is true for any other

reference frames such as Many other forms of torque equations are also possible, such as:

= 322 ( ) =

3

4 ...(2.15)

We can eliminate Irso that the equation will change to:

=

3

4 .....(2.16) 2.6 INDUCTION MOTOR CURRENTS CALCULATIONAccording to the single phase circuit of the induction motor shown in Fig. 1.4 one can write current

equations of stator and rotor in the d-q axis as follows:

=

..(2.17)

= ( ) ..(2.18) = ..(2.19) = ( ) ..(2.20)

By substituting and in the above equations we have the following equations according to the currentflow orientation and knowing that ( = ):


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=

+

..(2.21) = + ..(2.22) = .(2.23)

Referring to equations 2.5,2.6,2.7,2.8 we can write the flux linkage equations as followings in the per unit (b

is the base value of angular frequency and suppose induction motor is working in the synchronous speed):

1 = 1 = + .(2.24)

1

=

1 = + + ( ) .(2.25)

1 = ( ) 1

= ( )

+

.(2.26)1 = + ( )

1 = + ( ) + ( ) .(2.27)


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2.7 INDUCTION MOTOR ROTOR SPEEDThe speed rin the above equations is related to the torque by the following mechanical dynamic

equation: = + = +2 (2.28)Then we can rewrite the above equation for as follows:

= 2 ( ) .(2.29) Where:p: number of poles

J: moment of inertia (kg/m2)

2.8 SIMULATION OF THREE-PHASE INDUCTION MOTOR USING

MATLAB/SIMULINK

SIMULINK is a powerful software package for the study of dynamic and nonlinear systems. Using

SIMULINK, the simulation model can be built up systematically starting from simple sub-models. The

induction motor model developed may be used alone or it can be incorporated in an advanced motor drive

system, e.g. field oriented control.

Simulink is an environment for multidomain simulation and Model-Based Design for dynamic and

embedded systems. It provides an interactive graphical environment and a customizable set of block libraries

that let you design, simulate, implement, and test a variety of time-varying systems, including communications,

controls, signal processing, video processing, and image processing. Simulink is integrated with MATLAB,

providing immediate access to an extensive range of tools that let you develop algorithms, analyze and visualizesimulations, create batch processing scripts, customize the modeling environment, and define signal, parameter,

and test data.

In this project the simulation process will be starting from conventional modeling according to the

mathematical equations that are expressed in previous parts. The next plan is to improve the operation of

induction motor in the sense that how speed can be increased and in the same duration of time we take faster

rising, so two more techniques will be applied to enhance the control system, one will be fuzzy logic controller

and second one will be Adaptive Neuro-Fuzzy Inference System that usually is abbreviated to ANFIS. But


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before getting down controlling system First will discuss on conventional simulation. The principle of the

control system is shown in Fig. 2.3.

Fig.2.3: Principle of the control system

Over the years different mathematical models have been used to examine different problems associated

with induction motors. These range from the simple equivalent circuit models to more complex d,q models and

abc models which allow the inclusion of various forms of impedance and/or voltage unbalance. In this project

for more simplicity d-q models is preferred so that it will simplify the very complicated non-linear equations to

be solved and simulated. In Fig. 2.4 the block-diagram of induction motor and its drive that are simulated in

MATLAB/simulink are shown.

Fig. 2.4: Induction model with Conventional controller

In the Fig. 2.4 the structure of conventional simulation of induction motor is shown. According to the model

the AC voltage source that is the sinusdoial signal generator predefined by MATLAB/simulink, is applied to

Parks transformation matrix, then abc system will be converted to d-q form. In the next step the voltage sources


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that are imaged into d-axis and q-axis are applied to induction motor model. According to the previous section

and proven equations the induction motor equations are expressed in d-q frame. The outputs after calculating

the expressed equations, will be stator and rotor currents separately in the d-axis and q-axis, torque and rotor

speed. It can be the last stage but for more result clearance the currents are converted to abc frame with the help

of inverse Parks transformation. So according to existance of different parts in this model the following

headings will be discussed in details:

AC source

Abc to DQ0 Parks transformation

Induction motor in d-q model

Stator flux linkage calculation in q-axis

Rotor flux linkage calculation in q-axis

Stator flux linkage calculation in d-axis

Rotor flux linkage calculation in d-axis

Stator current calculation in the q-axis

Rotor current calculation in the q-axis

Stator current calculation in the d-axis

Rotor current calculation in the d-axis

Mutual flux linkage calculation in the q-axis

Mutual flux linkage calculation in the d-axis

Electrical Torque calculation

Rotor speed calculation

2.8.1 AC source

In the first stage balanced AC sources of sinnusdual wave forms are provided that are predefined blocks by

simulink software, and the data related to the these three phases like amplitude, frequency and phases are given

to the blocks through a GUI as given in Fig. 2.5: = 2 sin() = 2 sin 23 = 2 sin + 23


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Fig. 2.5: AC source of main model

2.8.2 abc to DQ0 Parks transformation

As its apparent from the equation below and block diagram, with the help of function blocks like sin,

cosin and some operational blocks like summation, multiplication and subtraction and one constant blocks for

applying 2/ 3value, the Parks transformation is easily modeled. The output of this block will concludes thevoltage sources in d-q frame.

0 = cossin cos( 2/ 3) cos( + 2/ 3)sin( 2/ 3) sin( + 2/ 3)

0.5 0.5 0.5

Fig. 2.6 abc to DQ0 Parks transformation model


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2.8.3 Induction motor in d-q model

In the Fig. 2.7 the overall model of IM is shown in Fig. 2.7 and the sub-blocks will be discussed later.

Fig. 2.7: Induction motor in d-q model

2.8.4 Stator flux linkage calculation in q-axis

In Fig. 2.8 all the flux linkages of stator and rotor in d-axis and q-axis and also mutual fluxes in d-axis and

q-axes are calculated.

Fig. 2.8: Flux linkage calculation model overall view

In Fig.2.9 the stator flux linkage in q-axis according to the equation that earlier is proven, is constructed.

1

= +

6

Wr

5

Te

4

idr

3

iqr

2

ids

1

iqs

TL

Te

Wr

rotor speed

iqs

Fqs

Fds

ids

Te

electrical torque

Fqr

Fqs

Fmq

iqr

iqs

Subsystem4

Fds

Fdr

ids

idr

Fmd

Subsystem2

Fmq

vqs

vds

Wr

Fmd

Fqr

Fqs

Fds

Fdr

Flux linkage calculation

3TL

2

Vds

1

Vqs


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Fig. 2.9: Stator flux linkage calculation in q-axis

Some variables like

and

are supplying from another blocks that are calculating these parameters.

The constant parameters like base value of rotor speed, stator resistance and stator leakage inductance will be

supplied through a GUI of induction motor which will modify th

Documents

1.Modelimi i Ngasjes Dhe Motorit Asinkron- Gjithashtu Edhe Modeli Matematik