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+//Chapter 7:Synchronous Motor and Brushless DC Motor Drives
+//Example 4
+clc;
+
+//Variable Initialization
+
+//Ratings of the synchronous motor
+Pm=8*10**6     // power rating in W
+f=50           // frequency in HZ
+Vl=6600        // line voltage in V
+pf=1           // unity power factor 
+P=6            // number of poles
+I=10           // rated field current in A
+Xs=2.8         // reactance of the windings in ohm
+Rs=0           // resistance of the windings in ohm
+Rd=0.1         // Dc link inductor resistance in ohms
+alpha=140      // constant firing angle in degrees 
+
+//Solution
+N=120*f/P                   //synchronous speed
+V=Vl/sqrt(3)           //phase voltage
+Is=Pm/(sqrt(3)*Vl*pf)  //rated current
+
+Id=%pi/sqrt(6)*Is  //Dc line current
+phi=180-alpha  //phase angle between Is and V in degrees
+
+//(i) When motor operates at rated current and 500rpm
+N1=500     //motor speed in rpm
+f1=N1/N*f  //frequency at N1
+V1=f1/f*V  //voltge at N1
+phi=phi*%pi/180
+Pm1=3*V1*Is*cos(phi) //power developed by the motor
+//for the 3-phase load commutated inverter
+alpha=alpha*%pi/180
+Vdl=(3*sqrt(6)/%pi)*V1*cos(alpha)
+Vds=-Vdl+Id*Rd
+cos_alpha_s=Vds/(3*sqrt(6)/%pi*V)
+alpha_s=acos(cos_alpha_s)  //in radian
+alpha_s1=alpha_s*180/%pi
+
+
+//(ii) Regenerative braking at 500rpm and at rated motor current
+alpha=0  //firing angle
+//When firng angle is zero then power factor is unity
+pf=1
+
+Pm2=3*V1*Is*pf   //power developed by the motor
+Ps=Pm2-Id**2*Rd  //power supplied to the source
+Vdl=(3*sqrt(6)/%pi)*V1*cos(alpha)
+Vds=-Vdl+Id*Rd
+cos_alpha_s=Vds/(3*sqrt(6)/%pi*V)
+alpha_s=acos(cos_alpha_s)   //in radian
+alpha_s2=alpha_s*180/%pi   //in degrees
+
+//Results
+disp('W',Pm1,"i)Power developed by the motor is:")
+disp('°',alpha_s1,"Source side converter firing angle is")
+disp('W',Ps,"ii)Power supplied to the source is:")
+disp("°",alpha_s2,"Source side converter firing angle is")
+//Answer given for firing angle in the book is wrong