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+
+//Chapter 6:Induction Motor Drives
+//Example 6
+clc;
+
+//Variable Initialization
+
+//Ratings of the star connected Induction motor which operates under dynamic braking
+f=50           // frequency in HZ
+P=6            // number of poles
+
+//Parameters referred to the stator
+Xr_=3.01       // rotor winding reactance in ohm
+Xs=Xr_         // stator winding reactance in ohm
+Rr_=4.575      // resistance of the rotor windings in ohm
+Rs=1.9         // resistance of the stator windings in ohm
+J=0.1          // moment of inertia of the motor load system in kg-m2
+Id=12          // given DC current
+
+N=1500         //given asynchronous speed
+//magnetization chacrateristic at the given asynchronous speed
+Im=[0.13,0.37,0.6,0.9,1.2,1.7,2.24,2.9,3.9,4.9,6,8,9,9.5]       //magnetization current
+E=[12.8,32,53.8,80,106,142,173,200,227,246,260,280,288,292]     //back emf
+
+//Solution
+Ns=120*f/P      //synchronous speed in rpm
+torque=[]
+speed=[]
+temp=[]
+Is=sqrt(2/3)*Id   //value of stator current for two lead connection
+Wms=2*%pi*N/60
+for i=2:14
+x=(Is**2-Im(i)**2)/(1+2*Xr_*Im(i)/E(i))   //x=Ir_**2
+Ir_=sqrt(x)       //required rotor current
+y=(E(i)/Ir_)**2-Xr_**2
+S=Rr_/sqrt(y)        //required slip
+N=S*Ns                    //required speed
+T=(3/Wms)*(Ir_)**2*Rr_/S  //required torque
+speed($+1)=N
+torque($+1)=T
+temp($+1)=T
+end
+mprintf("Hence the magnetization curve is")
+disp(speed,"Speed:in rpm")
+for i=1:13
+torque(i)=-1*torque(i)
+end
+disp(torque,"Braking torque :in N-m")
+
+//Results
+
+//Plot of of torque vs speed
+subplot(2,1,1)
+plot(torque,speed)
+xlabel('Torque, N-m') 
+ylabel('Speed, rpm')
+title('Torque vs Speed')
+xgrid(2)
+
+//Plot of Wm vs J/T
+inertia_over_torque=[]
+for i=3:13
+J_T=1000*J/temp(i)
+inertia_over_torque($+1)=J_T
+end
+disp(inertia_over_torque,"J/t :") 
+
+Wm=[1,4,8,12,16,20,25,55,95,125,160]  
+//the values of Wm are taken for the angular frequency with maximum value of Wms=50*pi rad/s
+subplot(2,1,2)
+plot(Wm,inertia_over_torque)
+xlabel('$Angular speed \omega_m$') 
+ylabel(' J/T,1*10e-2')
+title('$J/T   vs   \omega_m$')
+xgrid(2)
+x=[6.5,6.5]
+y=[2,4.5]
+plot(x,y,'blue')
+str=["${A}$"]
+str1=["${B}$"]
+str2=["${C}$"]
+str3=["${D}$"]
+str4=["${E}$"]
+xstring(6,2,str)
+xstring(6,4.5,str1)
+xstring(80,3.4,str2)
+xstring(156,8.3,str3)
+xstring(156,2,str4)
+
+mprintf("Hence from the plot the area ABCDEA between the curve and the speed axis for speed change ")
+mprintf("for synchronous to 0.02 times synchrnous speed is the stopping time which is equal to: 9.36 sec")