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+//Chapter 5:Dc Motor Drives
+//Example 5
+clc;
+
+//Variable Initialization
+
+//Ratings of the DC shunt motor which operated under dynamic braking
+Rb=1      //braking resisance in ohms
+Ra=0.04   //armature resistance in ohms
+Rf=10     //field resistance in ohms
+T=400     //load torque in N-m
+
+//Magnetisation curve at N1
+N1=600    //speed in rpm
+If=[2.5,5,7.5,10,12.5,15,17.5,20,22.5,25]    //field current in A
+E =[25,50,73.5,90,102.5,110,116,121,125,129] //back emf in V
+
+//Solution
+disp(If,"Field current   If:in A")
+x=(Rb+Rf)/Rb
+Ia = If * x                           //armature current
+Wm=2*%pi*N1/60
+Ke_flux=E / Wm     //Ke*flux=constant
+T=[]
+for i=1:10
+T($+1)=(Ke_flux(i))*(Ia(i))   //torque
+end
+disp(Ke_flux,"Ke_flux :")
+disp(T,"Torque  :in N-m")
+
+
+//Results
+
+//Plotting the values of Ke*flux vs If 
+If=[2.5,5,7.5,10,12.5,15,17.5,20,22.5,25]    //field current in A
+subplot(2,1,1)
+plot(If,Ke_flux,'y')
+xlabel('field current I_f')
+ylabel('Ke*flux')
+title('If  vs  Ke*flux')
+xgrid(2)
+
+//Plotting the values of  T vs If 
+If=[2.5,5,7.5,10,12.5,15,17.5,20,22.5,25]    //field current in A
+subplot(2,1,2)
+plot(T,If)
+xlabel('Torque T')
+ylabel('field current I_f')
+title('T vs If')
+xgrid(2)
+
+
+mprintf("\nFrom the plot we can see that when the torque is 400 N-m, ")
+mprintf("\nthe field current is If=19.3 A, and Ke*flux=1.898 when If=19.3 A")
+T=400          // braking torque in N-m
+If=19.13       // field current in A
+Ke_flux=1.898  // Ke*flux
+Ia=x*If
+E=If*Rf+Ia*Ra    //since E=V+Ia*Ra
+N2=(E/Ke_flux)*(60/(2*%pi))  //required speed
+mprintf("\nHence the required speed in is :%.1f rpm",N2)