2013 american-journal gapid

12
7/26/2019 2013 American-Journal GAPID http://slidepdf.com/reader/full/2013-american-journal-gapid 1/12 American Journal of Intelligent Systems 2013, 3(1): 1-12 DOI: 10.5923/j.ajis.20130301.01 Optimum Induction Motor Speed Control Technique Using Genetic Algorithm M. M. Eissa 1 , G. S. Virk 2 , A. M. AbdelGhany 1 , E. S. Ghith 3,*  1 Electrical Power and Machines Engineering at Helwan University, Egypt 2 Electrical Power and Machines Engineering at South Westphalia University, Germany 3 A master candidate in Systems Automation and Engineering M anagement; M aster Degree Program Faculty of Engineering Helwan University, Egypt Abstract Industrial processes are subjected to variation in parameters and parameter perturbations, which when significant makes the system unstable. In order to overcome this problem of parameter variation the PI controllers are widely used in industrial plants because it is simple and robust. However there is a problem in tuning PI parameters. So the control engineers are on look for automatic tuning procedures. In recent years, many intelligence algorithms are proposed to tuning the PI parameters. Tuning PI parameters using different optimal algorithms such as the simulated annealing, genetic algorithm, and particle swarm optimization algorithm. In this paper a scheduling PI tuning parameters us ing genetic algorithm strategy for an induction motor speed control is proposed. The results of our work have showed a very low transient response and a non-oscillating steady state response with excellent stabilization. The simulation results presented in this paper show the effectiveness of the proposed method, with satisfied response for GA-PI controller. Keywords Genetic Algorithm, PI Controller,  Induction Motor, Matlab, Simulink  1. Introduction Induction motors play a vital role in the industrial sector especially in the field of electric drives and control. Without  proper controlling of the speed, it is imposs ible to achieve the desired task for a specific application. AC motors,  particularly the squirrel-cage induction motors (SCIM), enjoy several inherent advantages like simplicity, reliability, low cost and virtually maintenance-free electrical drives. However, for high dynamic performance industrial applications, their control remains a challenging problem  because they exhibit significant nonlinear ities and many of the parameters, mainly the rotor resistance, vary with the operating conditions[1]. Field orientation control (FOC) or vector control[2] of an induction machine achieves decoupled torque and flux dynamics leading to independent control of the torque and flux as for a separately excited DC motor. FOC methods are attractive, but suffer from one major disadvantage (they are sensitive to motor parametric variations such as the rotor time constant and an incorrect flux measurement or estimation at low speeds [3]). Induction motors are widely used in various industries as  prime work-hors es t o produce rotational motions and forces . Generally, variable-speed drives for induction motors * Corresponding author: [email protected] (E. S . Ghith) Published online at http://journal.sapub.org/ajis Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved require both wide operating range of speed and fast torque response, regardless of load variations. The classical control is used in majority of the electrical motor drives. Conventional control makes use of the mathematical model for the controlling of the system. When there are system  parametric var iations or environmental disturbance,  behavior of system is not s atisfacto ry and deviates from the desired performance[4]. In addition, usual computation of system mathematical model is difficult or impossible. To obtain the exact mathematic model of the system, one has to do some identification techniques such as the system identification and obtain the plant model. Moreover, the design and tuning of conventional controller increases the implementation cost and adds additional complexity in the control system and thus, may reduce the reliability of the control system. Hence, the fuzzy based techniques are used to overcome this kind of problems. Efficient torque control of induction motor drives in combination with resonant DC-link input filters can lead to a type of stability problem that is known as negative impedance instability. To overcome this[5], proposed a solution to the above problem  by using the concept of non-linear system stabilizing controller with the plant. There are a number of significant control methods available for induction motors including scalar control, vector or field-oriented control, direct torque and flux control, sliding mode control, and the adaptive control[4]. Scalar control is aimed at controlling the induction machine

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Page 1: 2013 American-Journal GAPID

7/26/2019 2013 American-Journal GAPID

http://slidepdf.com/reader/full/2013-american-journal-gapid 1/12

American Journal of Intelligent Systems 2013, 3(1): 1-12

DOI: 10.5923/j.ajis.20130301.01

Optimum Induction Motor Speed Control Technique

Using Genetic Algorithm

M. M. Eissa1, G. S. Virk

2, A. M. AbdelGhany

1, E. S. Ghith

3,*

1Electrical Power and Machines Engineering at Helwan University, Egypt2Electrical Power and Machines Engineering at South Westphalia University, Germany

3A master candidate in Systems Automation and Engineering Management; Master Degree Program Faculty of Engineering HelwanUniversity, Egypt

Abstract Industrial processes are subjected to variation in parameters and parameter perturbations, which when

significant makes the system unstable. In order to overcome this problem of parameter variation the PI controllers are

wide ly used in industrial plants because it is s imple and robust. However there is a prob lem in tuning PI parameters. So the

control engineers are on look for automatic tuning procedures. In recent years, many intelligence algorithms are proposedto tuning the PI parameters. Tuning PI parameters using different optimal algorithms such as the simulated annealing,

genetic algorithm, and particle swarm optimization algorithm. In this paper a scheduling PI tuning parameters us ing genetic

algorithm strategy for an induction motor speed control is proposed. The results of our work have showed a very low

transient response and a non-oscillating steady state response with excellent s tabilization. The s imulation results presented

in this paper show the effectiveness of the proposed method, with satisfied response for GA-PI controller.

Keywords Genetic Algorithm, PI Controller, Induction Motor, Matlab, Simulink

1. Introduction

Induction motors play a vital role in the indus trial sectorespecially in the field of electric drives and control. Without

proper controlling of the speed, it is imposs ible to achieve

the desired task for a specific application. AC motors,

particularly the squirrel-cage induct ion motors (SCIM),

enjoy s everal inherent advantages like s implicity, reliability,

low cost and virtually maintenance-free electrical drives.

However, for high dynamic performance industrial

applications, their control remains a challenging problem

because they exhibit significant nonlinear ities and many of

the parameters, mainly the rotor resistance, vary with the

operating conditions[1]. Field orientation control (FOC) or

vector control[2] of an induction machine achievesdecoupled torque and flux dynamics leading to independent

control of the torque and flux as for a separately excited DC

motor. FOC methods are attractive, but suffer from one

major disadvantage (they are sensitive to motor parametric

variations such as the rotor time constant and an incorrect

flux measurement or est imation at low speeds [3]).

Induction motors are widely used in various industries as

prime work-horses to produce rotational motions and forces .

Generally, variable-speed drives for induction motors

* Corresponding author:

ehabsai [email protected] (E. S . Ghith)

Published online at http://journal.sapub.org/ajisCopyright © 2013 Scientific & Academic Publishing. All Rights Reserved

require both wide operating range of speed and fast torque

response, regardless of load variations . The c lassical control

is used in majority of the electrical motor drives.

Conventional control makes us e of the mathematical model

for the controlling of the system. When there are system

parametric variations or environmental disturbance,

behavior of system is not s atisfactory and deviates from the

desired performance[4].

In addition, usual computation of system mathematical

model is difficult or impossible. To obtain the exact

mathematic model of the system, one has to do some

identification techniques such as the system identification

and obtain the plant model. Moreover, the design and

tuning of conventional controller increases the

implementation cost and adds additional complexity in the

control system and thus, may reduce the reliability of thecontrol system. Hence, the fuzzy based techniques are used

to overcome this kind of problems. Efficient torque control

of induction motor drives in combination with resonant

DC-link input filters can lead to a type of stability problem

that is known as negative impedance instability. To

overcome this[5], proposed a solution to the above problem

by using the concept of non-linear system stabilizing

controller with the plant.

There are a number of significant control methods

available for induction motors including scalar control,

vector or field-oriented control, direct torque and flux

control, sliding mode control, and the adaptive control[4].

Scalar control is aimed at controlling the induction machine

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2 M. M. Eissa et al.: Optimum Induction Motor Speed Control Technique Using Genetic Algorithm

to operate at the steady state, by varying the amplitude and

frequency of the fundamental supply voltage[6]. A method

to use of an improved V/f control for high voltage induction

motors and its stability was proposed in[7]. The scalar

controlled drive, in contrast to vector or field-oriented

controlled one, is easy to implement, but provides

somewhat inferior performance. This control method

provides limited speed accuracy es pecially in the low speed

range and poor dynamic torque response.

Many researchers had worked on the fuzzy logic based

on-line efficiency control for an indirect vector controlled

IM drive. Bimal Bose et.al.[8] extended the same control

technique to a stator flux oriented electric vehicle IM drive

and then implemented the fuzzy controller by a dynamic

back propagation algorithm using an ANFIS controller.

They further verified the simulated results using an DSP

based hardware. Haider et.al.[9] Presented the des ign and

implementation of Fuzzy-SMC-PI methodology to control

the flux and speed of an induction motor. TheFuzzy-SMC-PI was basically a combination of Sliding

Mode Control (SMC) and PI control methodologies through

fuzzy logic, but the drawback being the chattering during

the t ime of switching.

In[10] and[11], the researchers implemented a fuzzy

logic controller to adjust the boundary layer width

according to the speed error. The drawback of their

controller is that it depends on the equivalent control and on

the system parameters. Two researchers, Takagi and

Sugeno developed a excellent control scheme for control of

various applications in the industrial sector. This controller

had many advantages over the other methods discussed sofar. Many researchers started using their models for their

applications. Zie, Ling and Jhang[12] presented a TS model

identification method by which a great number of systems

whose parameters vary dramatically with working states

can be identified via Fuzzy Neural Networks (FNN). The

suggested method could overcome the drawbacks of

traditional linear system identification methods which are

only effective under certain narrow working states and

provide global dynamic description based on which further

control of such systems may be carried out.

In the above mentioned paper, there were contribution for

their research and they solved many problems but there are

some limitation in the settling time o f the responses and the

proper selection of the rule base. The responses had taken a

lot of time to reach the final steady s tate value.

Because of the simplicity and robustness, PI controllers

are frequently used controllers in industries[13]. Parameter

adjustment of PI controllers is an old challenge in the field of

control system design. Some of methods have been proposed

to select the PI coefficients, but they are not completely

systematic methods and result in a poorly tuned controller

that needs some trail and e rror. So far, finding new methods

to automatically select PI parameters was interest of

researches[14]. In this paper the idea of des igning optimal PI

controller based on genetic algorith ms is defined and applied.

According to the controller type and location in c losed loop

control system. Then this idea can be verified and tested by

simulation results.

In the early 1960s Rechenburg (1965) conducted studies at

the technical university of Berlin in the use of an

evolutionary strategy to minimize drag on a steel plate[15].

Genetic algorithms were used by Holland (1975) and his

students at the University of Michigan in the late 1970s and

early 1980s to analyses a range of engineering problems[15]

and[16]. In particular, Goldberg (1983) used genetic

algorithms to optimize the design of gas pipeline systems.

Genetic algorithms are one of the efficient tools that are

employed in solving optimization problems[15].

In this paper, a sincere attempt is made to reduce the

settling time of the responses and make the speed of

response very fast by designing an efficient controller us ing

GA-PI control strategy. Here, we have control strategy for

the speed control of IM, which has yielded excellent resultscompared to the others mentioned in the literature survey

above. The results of our work have showed a very low

transient response and a non-oscillating steady state

response with excellent s tabilization.

2. Modeling of Induction Motor

2.1. Mathematical Model of the Induction Motors

In this study, the mathematical model of the system

consists of space vector PWM voltage source inverter,

induction motor, direct flux and the torque control. Aninduction motor model to predict the voltage required

achieving a desired output torque is given in[17]. Figure 1.

shows the power circuit of the 3-phase induction motor and

Figure 2.shows the equivalent circuit used for obtaining the

mathematical model of the IM.

Figure 1. Power circuit connection diagram for the IM

(a) d-axis

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American Journal of Intelligent Syst ems 2013, 3(1): 1-12 3

(b) q-axis

Figure 2 . Equivalent circuit of induct ion motor in d - q frame

An induction motor model is then used to predict the

voltage required to drive the flux, torque and the speed to the

demanded values. This calculated voltage is then synthesized

using the space vector modulation. The stator and rotor

voltage equations are given by[16].

sqd sd dt

d sd i s R

sd V λ ω λ −+= (1)

sd d sqdt

d

sqi s R sqV λ ω λ ++=

(2)

rqdArqdt

d rd i R

rd V r λ ω λ −+= (3)

rd dArqdt

d rqi RrqV r λ ω λ ++= (4)

where Vsd and Vsq, Vrd and Vrq are the direct axes and

quadrature axes stator and rotor voltages[16].

The squirrel-cage induction motor considered for the

simulation study in this thesis, has the d and q-axis

components of the rotor voltage zero. The flux linkages to

the currents are related by the Equation (5) as

==

r Lm L

r Lm L

m L s L

m L s L

M

rqird

i

sqi sd i

M

rq

rd

sq

sd

00

00

00

00

;

λ

λ

λ

λ

(5)

The electrical part of an induction motor can thus be

described by a fourth-order state space model which is given

in Equation (6), by co mbining equations (1-5) as[16]

,

)()(

)()(

+−−−−

−+−

−+−

−−+

=

qr

qr

ds

qs

r r r r emmr e

r r er r mr em

mme s s se

em se s s

qr

qr

ds

qs

i

i

i

i

sL R L sL L

L sL R L sL

pL L sL R L

Lm sL L sL R

v

v

v

v

ω ω ω ω

ω ω ω ω

ω ω

ω ω

(6)

where s is the laplacian operator. By superposition, i.e.,

adding the torques acting on the d-axis and the q-axis o f the

rotor windings, the instantaneous torque produced in the

electromechanical interaction is given by

−=

rq

i

rd rd

i

rq

P emT λ λ

22

3 (7)

The electromagnetic torque expressed in terms of

inductances is given by

−=

rqi

sd i

rd i

sqi

m L

P emT

22

3, (8)

The mechanical part of the motor is modelled by the

equation (9) as[16]

( )3

2 2m

P L i i i i T m sq rqT T Lrd sd d em L

dt J J eq eqω

− −−= = (9)

where, is angular speed, Tem is electromagnetic torque,

TL is load torque, is equivalent moment of inertia,

Lm is mutual inductance, Lr is rotor inductance, Ls is stator

inductance, and VDC is dc voltage .

2.2. Space Vector Puls e Width Modulation

The induction motor can be observed as a system of

electric and magnetic circuits, which are coupled

magnetically and electrically. A 3-Phase balanced sinusoidal

voltages given by[19].

,cos t mV An

V ω = (10)

,3

2

cos

−=

π ω t

mV

BnV

(11)

,3

2cos

+= π ω t mV

CnV (12)

are applied to the IM using the equation

++=Cn

va Bn

avan

vV 2

3

2 (13)

Through the 3-Phase bridge inverter shown in the Figure 1

which has got 8 permissible switching states. These 8

permissible switching states can be graphically represented

as shown in the Figure 3. The table 1 gives the summary of

the switching states and the corresponding phase-to-neutral

voltages of the isolated neutral induction machine[23].

Table 1. The inverter switching states

VCn VBn VAn C B A Vi

0 0 0 0 0 0 V0

-VDC/3 -VDC/3 2VDC/3 0 0 1 V1

-2VDC/3 VDC/3 VDC/3 0 1 1 V2

-VDC/3 2VDC/3 -VDC/3 0 1 0 V3

VDC/3 VDC/3 -2VDC/3 1 1 0 V4

2VDC/3 -VDC/3 -VDC/3 1 0 0 V5

VDC/3 -2VDC/3 VDC/3 1 0 1 V6

0 0 0 1 1 1 V7

eq J

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4 M. M. Eissa et al.: Optimum Induction Motor Speed Control Technique Using Genetic Algorithm

Figure 3. Diagrammatic representation of the sequence of the space vectors

3. Realization of GA-PI ControllerTuning Optimal Parameters

3.1. Proposed GA-PI Controller

It is possible to introduce and explain the following

computing procedure based on genetic algorithm for optimal

selection of controller parameters. This algorithm is clearly

shown in Figure 4. And can be e xplained with the following

steps: 1. Specify the controller type and location.

2. Start with a randomly generated population of size (MP

× NP). (i.e. population of controller parameters (gains) is

randomly generated according to a specified parameters

range). 3. Calculate the f itness f (x) of each chromosome x in the

population.

4. Apply elitism technique to retain one or more bestsolutions from the population.

5. Apply genetic algorithms operators to generate a new

population:

a. Select a pair of parent chromosomes from the

probability of selection being an increasing function of

fitness. Selection is done with replacement, which means the

same chromosome can be selected more than once to become

a parent. b. With probability PC, crossover the pair at a rando mly

chosen point (chosen with uniform probability) to form two

offspring. c. Mutate the two offspring at each locus with probability

Pm, and place the resulting chromosomes in the new

population. 6. Replace the current population with the new population.

7. If stopping criterion such as maximum number of

iteration is not met then go to step 3 (repeat s teps 3-7).

8. Display results and stop program.

To understand this algorithm, we should define the overall

system transfer function according to the type and location of

the controller. In addition, it is important to determine the

following parameters: Maximum population size MP,

Maximum number of generations MG, Number of controller

parameters NP, Range of controller parameters R,

Probability of crossover PC, Probability of mutation Pm and

The type of fitness function f(x).

The stop criterion is maximum nu mber of generations. Inthis paper a powerful design method based on real-coded

genetic algorithms to solve the minimization of the ISE

criterion is described. Genetic algorithms provide a much

simpler approach to off-line tuning of such controllers than

the rather complicated non-genetic optimization algorithms

[18]. However, in particular PI controllers have many types

and different structures, depending on the location of the

proportional, integral control, which can be placed in

forward path in cascade with the plant, or in the feedback

path .

Vs4

(011)

(001)

Vs3

Vs6

(101)

Vs5 (001)

Vs1 (100)

d-axis

(110)

Vs2

q-axis

Sector 1

Sector 6

Sector 5

Sector 4

Sector 3

Sector 2

Vs7

Vs0

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American Journal of Intelligent Syst ems 2013, 3(1): 1-12 5

Figure 4. Flowchart of Genetic PI Controller Algorithm

NO

yes

Generate new population

start

Set input GAs parameters MG ,MP, PC, Pm, N p,

and type of selection method.

Fitness

Calculation

Apply elitism technique, retain the best

solution, set iter.=0

Best controller parameters

IF

Iter. <MG

1stGAs operations

(selection)

2nd

GAs operations

(Crossover)

3rd

GAs operations

(Mutation)

End

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6 M. M. Eissa et al.: Optimum Induction Motor Speed Control Technique Using Genetic Algorithm

3.2. Tuning Genetic PI Controller

Figure 5 . Tuning genetic PI Controller

Figure 5. Represent a block diagram of the feedback

control system based on genetic PI controller. The controller

parameters are tuned by genetic algorithms starting from

initial population[14], which is generated randomly and now

it is important to calculate the fitness of each chromosome in

the population. This is achieved by setting these values to the

PI controller, to test the system output response by using unit

step input s ignal as shown in Figure 5.

3.3. Fitness Function

In PI controller design methods, the most common

performance c riteria are integrated absolute error (IA E), the

integrated of time weight square error (ITSE), integrated of

squared error (ISE) and integrated of time weight absolute

error (ITAE) that can be evaluated analytically in the

frequency domain[20, 21]. Thes e four integral performance

criteria in the frequency domain such as IAE, ISE, ITAE and

ITSE performance criterion formulas are as follows:

0

( ) . IAE t dt

= ∫ (14)

(15)

0

. ( ) ITA E t e t dt

= ∫ (16)

2

0

. ( ) ITS E t e t dt

= ∫ (17)

In order study we will select the fitness function (FF) is

reciprocal of the performance criterion, in the other words:

FF= ISE.In this paper a time domain criterion is used for evaluating

the PI controller. A set of good control parameters P and I

can yield a good response that will result in performance

criteria minimization in the time domain. These performance

criteria in the time domain include the overshoot, rise time,

settling time, and steady-state error.

4. GA–PI Controller Selection

4.1. GA-PI Controller Parameter Selection

To control the speed of an induction motor at 150 rad/sec.Therefore it is desired to improve the system response by

using genetic PI controller to enhance the transient response,

or using PI controller to enhance both transient and steady

state closed loop system response. Let us try to apply the

algorithm step by step to show you the activity of the

proposed algorithm. In addition the genetic algorithms

which are introduced in this thesis uses roulette wheel

selection method and the fitness function (ISE). It is desired

to find genetically the parameters of the PI controller, but

this need to define first the following genetic input

parameters in Table 2 and Genetic Output Results show in

table 3.

Table 2. Genetic input parameters

Selection

method MutationCrossoverR NPMGMP

Roulette

WheelUniform

Single

point

-200 to

20021020

Table 3. variable of GA-PI controller.Genetic Algorithm

values are given as (Ki = 180.0888, Kp = 188.2371).

The simulation results of GA-PI controller are shown in

Figure 6. Figure 6 shows the best and mean fitness during

generations. Note that an optimal solution is achieved after

the 4th

. The developed simulink model for the speed control

of IM using GA-PI shown in Appendix A2 .

Table 3. Genetic output results

Genetic output Results

ITSEK IK P

19.9119180.0888188.2371

2

0

( ). IS E e t dt

= ∫

Initial

population

PI controller

GA paramet er

tuning

Controlled

object

Initial

parameters

Best

parameters

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American Journal of Intelligent Syst ems 2013, 3(1): 1-12 7

Figure 6. Variation of fitness during generations. Best fitness and Mean fitness

Simulations are carried out in Matlab. The response curves of flux, s tator current, electromagnetic torque are shown in the

Figures 7-9 respectively.

Figure 7. Flux in case of GA-PI (TL=2 N.m at t=0 sec)

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 10

4

Generation

F i t n e s s v a l u e

Best: 3303.6662 Mean: 3303.6662

Best fitness

Mean fitness

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

time (sec)

f l u x ( w e b e r )

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8 M. M. Eissa et al.: Optimum Induction Motor Speed Control Technique Using Genetic Algorithm

Figure 8. Stator current in case of GA-PI (TL=2 N.m at t=0 sec)

Figure 9. Torque in case of GA-PI (TL=2 N.m at t=0 sec)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-500

-400

-300

-200

-100

0

100

200

300

400

500

time (sec)

s t a t o r c u r r e n t ( A )

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-50

0

50

100

150

200

250

300

350

time (sec)

T o r q u e ( N . m

)

electromagnetic torque (N.m)

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American Journal of Intelligent Syst ems 2013, 3(1): 1-12 9

Figure 10 shows the rotor speed performance at T L=2N.m and time zero load condition.

From the s imulation result shown in the F igure 10, it is observed that the response of the speed takes lesser time to reach

sett le value and obtains the desired value in a min time. A co mparison s tudy between the control performance using GA with

another technique used Mamdani control strategy[22] shown in the Figure 11, for the same model and the same parameter.

The comparison shows that the motor speed reached to 0.84 sec compared with other technique that reached to 1.4 sec

(ITAE=19.9119).

Figure 10. Speed in case of GA-PI (T L=2 N.m at t=0 sec)

Figure 11. Speed in case of Mamdani control strategy[22]

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-20

0

20

40

60

80

100

120

140

160

time (sec)

R o t o r s p e e d W

m

( r a d / s e c )

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10 M. M. Eissa et al.: Optimum Induction Motor Speed Control Technique Using Genetic Algorithm

Figure 12. Flux in case of GA-PI (TL=200 N.m at t=1.2 sec)

Figure 13. Stator current in case of GA-PI (TL=200 N.m at t=1.2 sec)

Figure 14. Torque in case of GA-PI (TL=200 N.m at t=1.2 sec)

Figure 15. Speed in case of GA-PI (TL=200N.m at t=1.2sec)

Another case study is taken to check the performance of

GA. The test is accured at TL=200, t=1.2sec. The motor

starts from standstill at load torque = 2 N.ms and, t =0.0 s, a

sudden full load of 200 N.ms at t=1.2 sec is applied to the

system controlled by GA-PI control.

Figures 12-15 flux, stator current, electromagnetic torque

and speed characteristics during step change in load torque at

t = 1.2 sec with GA-PI controller. These figures also show

that the GA-PI-based drive system can handle the sudden

increase in command speed quickly without overshoot,under- shoot, and steady-state error.

5. Conclusions

In this paper, a sincere attempt is made to reduce the

settling time of the responses and make the speed of

response very fast by designing an efficient controller us ing

GA-PI control strategy. Here, we have control strategy for

the speed control of IM, which has yielded e xcellent results.

A comparison study between the control performance using

GA with another technique used Mamdani control strategy

[22], for the same model and the same parameter. Thecomparison shows that the motor speed reached to 0.84 sec

compared with other technique used Mamdani control

strategy[22] that reached to 1.4 sec. The results of our work

have showed a very low transient response and a

non-oscillating steady state response with excellent

stabilization.

APPENDIX

A1. Squirrel Cage Induct ion Motor (SCIM) specs :

50 HP, 1800 rpm, 460 V, 60 Hz. 3-Phase, 2 pair of poles,

Squirrel Cage type IM, Rs=0.087 Ω, Ls=0.8 mH, Rr=0.228

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

time (sec)

f l u x ( w e b e r )

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-500

-400

-300

-200

-100

0

100

200

300

400

500

time (sec)

s t a t o r c u r r e n t ( A )

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-50

0

50

100

150

200

250

300

350

time (sec)

T o r q u e ( N . m

)

electromagnetic torque (N.m)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-20

0

20

40

60

80

100

120

140

160

time (sec)

R o t o r s p e e d W m ( r a d / s e

c )

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American Journal of Intelligent Syst ems 2013, 3(1): 1-12 11

Ω, Lr=0.8 mH, Lm=34.7 H, J=1.662 kg.m^2.

A2. Simulink

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