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//Chapter 6:Induction Motor Drives
//Example 12
clc;
//Variable Initialization
//Ratings of the star connected Induction motor are same as that of Ex-6.9
f=50 // frequency in HZ
Vl=400 //line voltage in V
P=4 // number of poles
N=1370 //rated speed
//Parameters referred to the stator
Xr_=3.5 // rotor winding reactance in ohm
Xs=Xr_ // stator winding reactance in ohm
Rr_=3 // resistance of the rotor windings in ohm
Rs=2 // resistance of the stator windings in ohm
//Solution
Ns=120*f/P //synchronous speed
N1=Ns-N //increase in speed from no load to full torque rpm
//(i)When f1=30Hz and 80% of full load
Ns=120*f/P
f1=30 //frequency
N2=0.8*N1 //increase in speed from no load to 80% of full torque rpm
Ns1=f1/f*Ns
N=Ns1+N2 //machine speed
//(ii)At a speed of 1000rpm
N2=1000 //given speed in rpm
N3=N2-N1 //synchronous speed
f3=P*N3/120 //required frequency
//(iii)When frequency is 40Hz and speed is 1300 rpm
f4=40 //frequency in hz
N2=1300 //speed in rpm
Ns=120*f4/P //required synchronous speed in rpm
N4=N2-Ns //increase in speed from no load speed in rpm
Tf=25.37 //full load torque as calculated in Ex-6.11
Tm=-N4/N1*Tf //motor torque
//(iv) when the motor is under dynamic braking
//Results
mprintf("(i)Required speed is :%d rpm",N)
mprintf("\n(ii)Required frequency is:%d Hz",f3)
mprintf("\n(iii)Required motor torque :%.2f N-m",Tm)
mprintf("\n(iv)The value of the frequency,speed and motor torque calculated in (i),(ii) and(iii)")
mprintf(" \nwill be the same when the motor is operated under dynamic braking")
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