efficiency improvement of squirrel project report

8/3/2019 Efficiency Improvement of Squirrel Project Report

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Efficiency Improvement of Squirrel

Cage Induction Motor

Prepared By:

JAYESH N. PATEL (080400109028) [B.E. Sem VII-EE]

JATIN J. PATEL (080400109026) [B. E. Sem VII-EE]

UMESH D. PATEL (080400109045) [B. E. Sem VII-EE]

DEPERMENT OF ELECTRICAL ENGINEERING

SANKALCHAND PATEL COLLEGE OF ENGINNEERING

VISNAGAR


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ABSTRACT

In the modern process industries & field where is a need of prime mover

induction motor is gift of electrical engineers. Since there is so much advantage of using

an induction motor. The scope of the project deals with the possibility of the efficiency

improvement for the three phases, low voltage, squirrel-cage induction motor. Theefficiency of an electrical drive depends essentially on that of the electrical motor.

Therefore, every improvement of the electrical motor efficiency is very important. As a

costumer, it is better to take in to account not only the motor price, but also the cost of

the used energy during the whole lifetime of the motor. For the three phases, low

voltage, induction motor, the used material for the squirrel cage is aluminum because of

his the price - lower in comparison with that of the copper convenient for the existing

technological solutions. As it is known, the coppers resistivity is lower then that of

aluminum, and therefore the copper squirrel cage losses decrease. Till now, the actual

technology has no solutions for low voltage motors and new solutions are necessary in

the technological area. Industrial induction machines with squirrel cage, considering the

rotor losses decreasing, the material cost increase and the saved energy for the whole

machine life.


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INDEXCHAPTER CONTENT PAGE

1 BASICS OF SQUIRREL CAGE INDUCTION MOTOR 1-41.1SQUIRRELCAGE INDUSTIOH MOTOR

1.2GENERAL PRINCIPLE

1.3COMPARISION OF SQUIRREL CAGE I.M.WITH WOUND

ROTOR I.M.

1.4CONSTRUCTION

1.4.1 Stator

1.4.2 Rotor

1.4.3 Another Parts Of Squirrel Cage Induction

2 LOSSES IN SQUIRREL CAGE INDUCTION MOTOR 5-7

2.1 IRON LOSSES

2.1.1Hysteresis losses

2.1.2Eddy current losses

2.1.3Harmonic eddy current losses

2.2OHMIC LOSSES

2.3MECHANICAL LOSSES

3 SIMULATION OF SQUIRREL CAGE I.M. USING MATLAB 8-25

3.1INTRODUCTION OF MATLAB3.2DESIGN PROBLEM

3.3 FLOW CHART

3.3MATLAB PROGRAMMING3.5OUTPUT

WORK REMAIN 26 REFRENCES 27


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CHAPTER-1

BASICS OF SQUIRREL CAGE INDUCTION

MOTOR


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1.1 SQUIRREL CAGE INDUCTION MOTOR:-

The rotor drum is provided with a number of circuler holes,Parallel to shaft and

solid copper or aluminium bars are plased in these holes and all these bars are welded to two end

rings.

1.2GENERAL PRINCIPLE:-

As a general rule,conversion of electrical power into mechanical place in the

rotating part of an electrical motor. In D.C.motor, the electrical power is conducted

directly to the armature (i.e. rotating part) through brushes and commutator. Hence un

this sense, a D.C. motor can be called a powertakes conduction motor. However in A.C.

motor, the rotor dose not receive electrical power by conduction but by induction in

exactly in same way as the secondary of a two-winding transformer receives its powerfrom the primary.That is why such motor are know as induction motors. In fact, an

indution motor can be treated as rotating transformer i.e. one in which primary winding

is stationary but the secondary is free to rotate.

1.3COMPARISION OF SQUIRREL CAGE I.M. WITH WOUND

ROTOR I.M.

No sliprings,brush gear The star delta starter are sufficient for starting. It has a slightly higher efficincy. It is cheaper & rugged in cunstrution. It has a larger space for fans & thus the cooling condition are better.


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1.4 CONSTRUCTION:-

There is very little difference between the AC motor and AC generator. The rotor

is supported by bearings at each end. The stator is freed is position to the inside of themotor frame. The frame encloses all the components of the motor.

1.4.1 STATOR:-

The motor stator is the stationary winding bolted to the inside of the motor

housing. The stator windings have a very low resistance. The three-phase AC generator

armature is built very similar to the three-phase AC motor stator. Each machine has the

stationary conductor winding insulation its entire length to prevent turn-to-turn short.

The winding is also insulation from the frame. The motor stator winding is identical to

a generator armature that has a like amount of poles. Each winding is overlapped and is

electrical and mechanically 120 degrees out of phase.


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1.4.2 ROTOR:-

The rotor looks like a solid cylinder supported at each end by bearings. The bars

embedded in the laminated cylinder at an angel almost parallel to the rotor shaft. At

each end of the cylindrical rotor core, these are shorting rings. Each end of a bar of is

connected to the sorting rings. The short-circuited rotor bars become a transformer

secondary. The magnetic field established in the stotor induces an EMF in the rotor

bars. The rotor bars and the shorting rings complete a circuit flow is then established in

these rotor bars. Remember, whenever a current flow is established so is magnetic field.Since this magnetic field is property of induction and induction opposes that which

creates it, the magnetic field pole in the rotor is of opposite polarity of the stator field

pole that generated it. Magnetism principles apply, and the rotors polarity is attracted

to the stators opposite polarity. The revolving field of the stator, in effect the revolving

magnetic polarity, pulls and pushes the initially established rotor field in rotor field in

the rotor. The pulling and pushing produces torque, and the motor rotor turns.

1.4.3ANOTHER PARTS OF SQUIRREL CAGE I.M.:- Air gap: Air gap provides the space for the rotating magnetic field between stator &

rotor. Frame: Its function is to provide mechanical support, to the entire construction. Fan: The fan rotates with the rotor, its function is to cool down the motor.Slip rings:

The rotor winding terminals are permanently connected to the slip rings. The sliprings

are continuously in contact with three brushes which are pressed against slip rings.


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CHAPTER-2

LOSSES IN SQUIRREL CAGE INDUCTION

MOTOR


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LOSSES IN SQUIRREL CAGE I.M.

2.1 Iron Losses

The main factors of iron losses are the hysteresis losses and the eddy current losses. The

hysteresis losses depend on the magnetic properties of the iron used and the eddy current losses

on the lamination thickness, frequency f, flux density B and the resistivity of the iron. Iron

losses occur all over the iron and they are a function of (local) flux density and frequency. In

addition, there are also harmonic losses which mainly occur on teeth and iron surfaces and are

caused by harmonics in the flux density.

2.1.1 Hysteresis losses

The area inside the hysteresis loop represents hysteresis losses in the material. Theincreasing of the amount of silicon in iron reduces the area of the hysteresis loop. Silicondecreases the friction between the Weiss domains, but also impairs to some degree thesaturation flux density. The losses correspond also to the frequencyf.

2.1.2 Eddy Current losses In lamination

The alternating magnetic flux creates electro motive forces (emf) inside the material it

flows through. These emfs fluctuate at the same speed as the flux and similarly create eddy

currents normal to the flux path, i.e. the eddy currents circle around the flux.There are several

factors that affect the eddy current losses, but usually the outer dimensions of the motor, flux

density and the frequency are constants and so there are only two variable factors left. The

thickness of the lamination seems to have the strongest influence in eddy current losses. Some

problems arise if the plate is very thin. First it is very difficult to manufacture and handle and

second the filling factor becomes small because at least one side of the laminated plate has a

non magnetic insulation layer which prevents eddy currents from travelling between the plates.

Another possibility is to increase the resistivity of the plate. One way of achieving this is to add


10/31

2.1.3 Harmonic eddy current losses

There are two main causes of harmonics in the air-gap flux density distribution of the

machine when used with a sinusoidal supply: the permeance harmonics and the winding

harmonics. Air gap permeance function generates flux density fluctuations on the rotor

surface. These flux density fluctuations induce high frequency eddy currents that generatelosses on the surface of the rotor. One method to flatten the permeance function is to use some

semi-magnetic material to close the stator slot opening. The purpose of the slot-wedge is to

lead the flux under the slot opening. The magnetic properties of the wedge should be

somewhere between stator iron and air and its electric conductivity should be low. Choosing

the material is a question of optimisation between the power factor of the machine and

harmonic losses on the rotor surface. Increasing the permeability of the slot-wedge flattens the

permeance function, but also increases slot leakage flux.

2.2 Ohmic losses

The stator windings are usually made of enamelled copper wires and the rotor cage ofcast aluminium. The main winding losses are caused by the fundamental and harmoniccurrents, but also skin and proximity effects contribute to the losses. The stator windingresistanceRs as a function of ls length of the stator winding, Asb is the cross-section area of astator bar and the resistivity of copper (1.72 10-8 m at 20 C) and the coefficient of resistivityis = 410-3 K-1.Tthere are four parameters that affect the stator resistance. If the materialcross-section area can be increased or the length of the winding decreased. Both acts decreasethe stator resistance. The calculation of the rotor resistance is much more complicated thanthat of the stator.Because of the shape of the ring, the current path on the outer part of the ringis much longer than in the inner part. This leads to unequal current density in the ring. Both

iron and winding losses are greatly affected by the size of the motor. Usually an energyoptimal motor is larger than the present standard motors.

2.3 Mechanical losses

In small induction machines the mechanical losses are usually about 10 % of the totallosses. The main factors that affect on windage losses are the rotors peripheral velocity,Thesmoothness of the rotor and stator surfaces and the length of the air-gap. The smaller the air-gap, the bigger the windage losses and also the permeance harmonic losses presented earlier,but on the other hand increasing the air-gap increases the need for magnetising current. Theair-gap length has to be optimised between these three factors. The earlier mentioned stator

semi-magnetic slot-wedges smoothen the stator surface, and thus also decrease the windagelosses.


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CHAPTER -3

SIMULATION OF SQUIRRELCAGE I.M. USING

MATLAB


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3.1 INTRODUCTION OF MATLAB:-MATLAB is a software package for high-performance numerical computation and

visualizationun. It provides an interactive environment with hundreds of built in functions for

technical computation, graphics, and animation. Best of all, it also provides easy extensibility

with its own high level programming language. The name MATLAB stands for MATrixLABoratory.

MATLABs built in functions provide excellent tools for linear algebra computations,

delta analysis, single processing, optimization, numerical solution of ordinary differential

equations (ODEs), quadrature, and many other type of scientific computations. Most of these

functions use state-of-art algorithms. These are numerous functions for 2-D and 3-D graphics

wellas for animations, Also for those who cannot do without their Fortran or C codes. MATLAB

even provide an external interface to run those programs for within MATLAB. The user,

however, is not limited to the built in functions; he can write functions in the MATLAB

language. Once written, these functions behave like a built in function. MATLABs language isvery easy to learn and easy to use.

These are also several optional Toolboxes available from the developers of MATLAB.

Thase toolboxes are collections of functions written for special application such as Symbolic

Computation, Image Processing, Static, Control System Design, Neural Network, etc. The basic

building blocks of MATLAB is matrix. The function data type is are array. Vectors, scalars, real

matrices and complex matrices are all automatically handled as special cases of the basis data

type. What is more, you almost never have to declare the dimensions of matrix. MATLAB

simply loves matrices and matrix operations. The built in functions are optimized for vector

operations. Consequently, vectorized. Commands or code run much faster in MATLAB.


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3.2 DESIGN PROBLEM:-

As reference to ELECTRICA MACHINE DESIGNE by A.K.sawhney Design Problem-

1,Page No. 656

Example:-Design a 2.2kw, 400W,3-phase,50Hz,1500 synchronous r.p.m. squirrel cage induction

motor. The machine is to be started by a star-delta starter. The efficiency is 0.8 and power factoris 0.825 at full load.

Soln:

Main Dimensions:-Synchronous speed Ns=1500/60

=25 r.p.s

No. of poles p=2f/ns=4

The machine is meant to be sold in a highly competitive market and therefore its price

is the major consideration characteristics like efficiency and power factor can be sacrificed. In

order to design a cheap machine we must use higher value for specific electrical and magnetic

loading. Assuming

Bav=0.44Wb/m; ac=21000A/m and Kw=0.955

Output co-efficient Co=11kwBavac10-3

=110.9550.442100010 -3

=97

KVA input Q=2.2/(0.80.825) = 3.333

..

. Product D2L = (Q/Cons) = (3.33/9725) =1.37510

-3 m3

For cheap design, ratio L/ should be between 1.5 to 2 Assume L/=1.5

Or (L/(D/4))=1.5 or L=1.18D

..

. 1.18D3=1.37510-3

Or D=0.105m, L=0.125, and =0.0825m

As the length of core is 0.125 and therefore there is no necessity of providing any radial

ventilating duct

..

. .Net iron length Li=0.90.125=0.1125 Lohys 0.5mm thick lamination are used for the

machine.


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STATOR DESIGN:- Winding:-The machine is to be designed for delta connection as it is started by a star delta starter

.

.

. stator voltage per phase Ea=400V

Flux per pole m=Bav**L=0.44*0.0825*0.125= 4.5410-3Wb

Stator turns per phase Ts= 400 = 416

4.44504.5410-30.955

The slot pitch should between 15 to 20 mm but can be less than 15 mm for small machine

using semi-enclosed slots.

Taking slot per pole phase qs= 2

Total stator slot Ss= 342= 24

Stator slot pitch Yss=0.105103/24 = 13.75mm

Total stator conductor =6Ts =6416=2496

Stator conductor per slot Zs=2496/24=104

Mush winding is tapered semi enclosed slot is used for the stator. Mush winding is a single

layer winding and the total no. of stator coil is equal to half the no of stator slots i.e.12.

Coil span Cs=slot/poles 24/4 =6

But the coil span should not be an even integer in case of mush winding. Therefore, a coil

span of slots is used. Thus the coil are chorded by one slot pitch.

Angel of chording =(1/6)180 =30

..

. Pitch factor Kp=cos/2 =0.966

Distribution factor for 2 slot per pole per phase, Kd= sin60/2 =0.966

sin60/(22)

..

. Stator winding factor Kws=KsKp =0.9660.966 =0.933

Conductor size:-


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Stator current per phase Is = 2.2103 = 2.77A34000.80.825

Stator line current =32.77 =4.8A

Choosing a current density of 4A/mm2

Area of stator conductor required = 2.77/4 = 0.6925mm2

Diameter of conductor (bare) required = 0.94mm

From table 17.7, the nearest standard conductor has bare diameter d=0.95m

..

. Area of stator conductor s=2.77/0.709 =3.91A/mm2

Diameter of enameled conductor d1=1.041mm(using medium covering. See table 17.7)

Slot dimension:-Space required for bare conductor in a slot =Zssas=1040.709 = 73.6 mm

2

Taking space factor 0.4 for the slot

Area of each slot 73.6/0.4=184.3mm2

Before deciding the slot dimensions to give the above area, the minimum tooth width

that would keep the flux density within limit must be found. The maximum allowable flux

density is 1.7 W/m2

Minimum width of stator teeth (wts)min= m = 4.5410-3

1.7Ss/pLi 1.7(24/4)0.1125

= 3.95mm

A tooth of constant width 6.0 mm is taken. The dimensions of slots are worked as under:

Take lip =1mm and wedge =3mm.

.

.

.Slot width at AA=(105+24+2h) - 6 =8.8mm

24

And width of slot at bottom= (105+24+2h) - 6 =8.8+h mm

24 12


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Area of conductor portion of the slot =1h(8.8+h+8.8) =184mm2; h=17mm

2 12

..

.width at the bottom of the slot=8.8+17 =13.2mm

12

And depth of slot dss = 17+4 = 21mm

Length of mean turn Lmts=2L+2.3+24 =0.68mm

Stator Teeth:-Flux density in stator core = m = 4.5410

-3 =1.12b/m2

Ss/pWtsLi (24/4)610-30.1125

This is a good figure as there is no saturation and also the teeth are not being worked at flux

density.

Stator Core:-Flux in stator core = (4.5410-3)/2 = 2.2710-3wb

Assume flux density 1.2Wb/m2

..

.Area stator core Acs= 2.2710-3 = 1.8910-3m2

1.2

Depth of stator core dcs =1.8910-3 =16.810-3m2

0.1125

Taking the core length dcs = 17mm

Flux density stator core Bcs=(16.8/17)1.185wb/m2

Outside diameter of stator lamination Do=D+2dss+2dcs=105+2(21+17) = 181mm


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3.3FLOW CHART

MAIN DIMENSIONS:-

START

Power(p),phase(m),freq(f),synch.Speed(Ns),efficiency(n),p.f.(pf),Specific

magnetic loading(Bav),electric loading(ac),winding

P=(120*f)/ns

Q=p/(n*pf)

Co=11*Bav*ac*kw/1

A=(L/t)*/p

D^2L/Q(Co*Ns)

D=(D^2L/a)^1/3

L=a*D

Li=ki L-nd*Wd

END


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STATOR DESIGN

Slot/pole/phase

No

YES

START

Input Voltages(Es),ConnectionType,StatorWinding

F=Es/ 4.44*f*F*kw

F=Bav*L*T

Ss=m*p*qs

Yss=*D/Ss

T=6*Ts

Zss=T/Ss

Ts=Zss*Ss

Ts=Tc/6

Is Ts & Ts

are Equal

1

Modify Bav


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Assume Current density

In stator Cond

For Rect. Cond For Circular Cond.

Input sd,sld

Input sw,slw

1

Inte er Value Of Cs=Ss/

Kp=cos(/(2*Cs))

Kd=sin(qs*(/(2*cs)))/(qs*sin(/(2*Cs)))

Kws=k *kd

Is= P*1000 / m*Es*n* .f.

As=Is/Id

Dimension of insulated Cond.

d=((4*As)/)^0.2

Dimension of insulated Cond.

Modified Area of Cond.

dss=sd+sld+swr+Lip+slackd

2

Dimension of Rect.Cond.


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No

yes

Flux Density In

2

Wss=sw+slw+slackw

AA=(*(D*1000))/Ss

Wt=AA-Wss

Fd=(F*p*1000)/(Ss*Wt*Li)

Exceeds the Max

Value 1.7 Wb/m^2

Change Slot

Dimension

Lmts=2*L+2.3*T+0.24

Fs=F/2

Acs=Fs/Fds

Dcs=acs/Li

Do=(D^100)+(2*(dss+Dcs*1000)

End


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3.4 MATLAB PROGRAMMING:-

INPUT:-Kw =input(type value of kw rating: )

V=input(type value of voltage: )

n=input(type value of rated speed in r.p.m.: )

e= input(type value of efficiency: )

pf= input(type value of pf: )

Bav= input(type value of Bav: )

ac= input(type value of ac: )

Kw= input(type value of kw: )

x= input(type value of 1/t =: )

cont =input(type 1 for the STAR conn.=Y && 2 for DELTA conn.=D);

f=50

p=120*f/n

m=3

ns=n/60

fprintf(synchronous speed ns =%f r.p.s. ,ns);

Main Dimensions:-Co=11*kw*Bav*ac/1000

Q=kw/(e*pf)

D=((Q*p)/(Co*ns*pi*x))^(1/3)

fprintf(Diameter of the core =%f m ,D);

L=(pi*D*x)/p

t=pi*D/p

fprintf(Length of the core L =%f m,L);


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if(L


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Stator DesignIf(conn==2);

Es=V

else

Es=V/(3^0.5)

end

qs=input(input value of stator slots per pole per phase: )

phi=Bav*t*L

fprintf( Flux per pole phi =%f wb ,phi);

Ts1=Es/(4.44*f*phi*kw)

fprintf( No. of stator Turns per phase=%f ,Ts1);

Ss=m*p*qs

fprintf(No of stator Slot Ss=%d ,Ss);

yss=(pi*D*1000)/Ss

fprintf(stator slot pitch(yss)=% mm,yss);

Z=round(6*Ts1)

fprintf( Total stator conductor Z=%d ,Z);

Zss=round(Z/Ss)

Fprintf( stator conductor per slot Zss =%d ,Zss);

Ts=Zss*Ss/6

Fprinf(No. of stator Turns per phase Ts=%d,Ts);

If ((Ts-Ts1)>5)

Fprintf(it is need to change the slot per pole per phase);

Break;

Else


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Bav1(Ts1/Ts)*Bav

phi=Bav1*t*L

Cs=Ss/p

fprintf( coil span Cs =%f ,Cs);

if rem(Cs,2)==0

alpha=(1/Cs)*(180)

kp=cos(pi/(2*Cs))

fprintf(pitch factor kp =%f ,kp);

else

alpha=0

kp=1

end

kd=(sin(qs*(pi/(2*Cs)))/(qs*sin(pi/(2*Cs))))

fprintf(Distribution factor kd =%f ,kd);

kws=kp*kd

fprintf( stator winding factor Kws= %f ,Kws);

end

Is=((KW*1000)/(38Es*pf*e))

fprintf( Value of stator current/phase(Is)=%f A,Is);

dens=input(type value of dens= )

As=Is/dens

if (As


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d=input(type value of d from table: ,);

As=(pi/4)*(d^2)

Fprintf(Area of stator conductor As=% mm^2,As);

Dens1=Is/As

Fprintf(Current density of stator conductor %f,dens1);

D1=input(dia of enameled conductor from table 23.7: );

modA=(pi/4)*(d1^2)

fprintf( modified area of the conductor =%f mm^2,modA);

else

fprintf( use rectangular conductors)

modA=input(input area from tabte 23.1: %f);

lc=input(thichness of conductor= )

wc=input( width of conductor= )

end

fprintf( SLOT DIMENSION);

check=input( rectangular conductor input 1 & round conductor input 2: )

if (check==1)

sd=input(input no of conductor in depth= )

sld=input(input amount of insulation along the depth of conductor= )

slack=input(enter the suitable slack(in mm)= )

swe=3

lip=1

Dss=(sd*lc)+3*sld+lip+swe+slack

fprintf(depth of slot=%f,Dss);

sw=input(input number of conductor in width= )


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slw=input(input insulation along the width of conductor= )

slackw=input(enter the suitable slack(in mm)= )

wss=(sw*wc)+2*slw+slackw

fprintf(width of slot=%f,wss);

else sd=input(input no of conductors in depth= )

sld=input(input amount of insulation along the depth of conductor= )

slack=input(enter the suitable slack(in mm)= )

swe=3

lip=1

Dss=(sd*d1)+2*sld+lip+swe+slack

fprintf(depth of slot=%f,Dss);

sw=input(input number of conductor in width= )

slw=input(input insulation along the width of conductor= )

slackw=input(enter the suitable slack(in mm)= )

wss=(sw*d1)+2*slw+slackw

fprintf(width of slot=%f,wss);

end

AA=(pi*(D*1000))/Ss

fprintf(slot pitch=%f,AA);

wt=AA-wss

fprintf(teeth width=%f)

Fd=(phi*p*1000)/(Ss*wt*Li)

fprintf(Flux density in the stator teeth Fd=%f ,Fd);

fprinf(The value of Fd should be LESS THAN 1.7wd);

fprinf(WANT TO MODIFY THE FLUX DENSITY?????);


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Q=input(FOR YES INPUT 1 AND FOR NO INPUT 2= )

if(Q==2)

fprintf(the flux density is within limit);

Lmts=2*L+2.3*t+0.24

fprintf(length of mean turn Lmt =% ,Lmts);

Fs=phi/2

Fds=1.2

Acs=Fs/Fds

Dcs=Acs/Li

dcs1=round(Dcs*10^3)

Bcs=(Dcs*10^3/dcs1)*Fds

Do=(D*1000)+(2*dcs1)+(2*Dss)

fprintf(outer dia of stator lamination Do =%f ,Do);

else

fprintf(change slot dimension);

break

end


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3.5 OUTPUT:-

Type value of Kw Rating: 2.2

Type value of Voltage: 400

Type value of rated speed in r.p.s.: 25

Type value of efficiency: 0.8

Type value of p.f.: 0.825

Type value of Bav: 0.44

Type value of ac: 21000

Type value of kw: 0.955

Type value of 1/t: 1.5

Type value of p: 4

Type 1 for the STAR connection=Y && 2 for DELTA connection=D1

Co=

97.0662

Q=

3.3333

D=

0.1053

L=

0.1240

t=

0.0827

Nd=

0

Li=


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0.1116

>>


30/31

WORK REMAINS:-

Get the complete simulation using MATLAB. Analysis differents techniques efficiency improvement of squirrel cage induction motor. Make hardware of squirrel cage induction motor. Make final report & presentation.


31/31

References:-

1) T. Tudorache, L. Melcescu and V. Petre, high Efficiency Squirrel CageInduction Machines, International Conference on Renewable Energies and Power

Quality (ICREPQ09) Valencia (Spain), 15th to 17th April, 2009

2) T.Jokinen,Reduction of Losses in Electrical Machines and Transformer . HelsinkiUniversity of Technology Laboratory of Electromichanics . Report no 17(in

Finnish),1983.

3) A.K.Sawhney A course in electrical machine design,Dhanpat Rai Pub.2007,Chp.-10Three Phase Induction Motor.

4) B.L.Thareja Electrical Technology,S.Chand Pub.2007,Chp-9 Induction Motor5) http://www.mathworks.com6) http://en.wikipidia.org/wiki/induction_motor
http://www.mathworks.com/http://www.mathworks.com/http://en.wikipidia.org/wiki/induction_motorhttp://en.wikipidia.org/wiki/induction_motorhttp://en.wikipidia.org/wiki/induction_motorhttp://www.mathworks.com/

efficiency improvement of squirrel project report

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