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diff --git a/3811/CH3/EX3.1/Ex3_1.jpg b/3811/CH3/EX3.1/Ex3_1.jpg
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+o//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.1
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vrms=110; //source voltage of the circuit in volts
+alpha=90; //triggering angle in degree
+Vm=Vrms*(2)^(1/2); //maximum voltage in volts
+Vave=(Vm/(2*%pi))*(1+cosd(alpha));
+R=(0.2*(Vave)^(2))+5; //load resistance in ohm
+Iave=Vave/R; //average current of the load
+disp(Iave,'The average current when the triggering angle 90 degree in ampere is:')
diff --git a/3811/CH3/EX3.10/Ex3_10.jpg b/3811/CH3/EX3.10/Ex3_10.jpg
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.10
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+f=2; //switching frequency of chopper in kilohertz
+Vs=80; //source voltage in volts
+k=.3; //duty ratio
+R=4; //load resistance in ohm
+mprintf("\na.To calculate on time and switching period:")
+t=1/f; //switching period in milli sec
+ton=k*t; //on time in milli sec
+mprintf("\nThe switching period and on time in milli second are %f %f",t,ton)
+mprintf("\nTo calculate average voltage across the load:")
+Vave=k*Vs;
+mprintf("\nThe average voltage across the load is %d volt",Vave)
+mprintf("\nc.To calculate average voltage across the load:")
+Vdave=(1-k)*Vs; //obtained by integrating Vs with respect to ton and t
+mprintf("\nThe average voltage across the load is %d volt",Vdave)
+mprintf("\nd.To calculate average current of the load:")
+Iave=Vave/R;
+mprintf("\nThe average current of the load is %d ampere",Iave)
+mprintf("\ne.To calculate load power:")
+P=Vave*Iave;
+mprintf("\nThe load power is %d watt",P)
diff --git a/3811/CH3/EX3.12/Ex3_12.jpg b/3811/CH3/EX3.12/Ex3_12.jpg
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.12
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+f=500; //frequency at the load side in Hz
+t=1/f; //time for one cycle in sec
+tseg=t/6; //time of the switching segment in sec
+tcon=3*tseg; //conduction period of each transistor in sec
+tcon1=tcon*10^3; //conduction period of each transistor in msec
+disp(tcon1,'The conduction period of each transistor in msec is')
diff --git a/3811/CH3/EX3.13/Ex3_13.jpg b/3811/CH3/EX3.13/Ex3_13.jpg
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diff --git a/3811/CH3/EX3.13/Ex3_13.sce b/3811/CH3/EX3.13/Ex3_13.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.13
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+d=.25; //duty ratio
+Vdc=150; //source voltage in volts
+Vab=((2*d)/3)^(1/2)*Vdc; //rms voltage applied to the motor winding with FWM
+disp(Vab,'The rms voltage applied to the motor winding with FWM in volts is:')
+Vab1=(Vab/d^(1/2)); //rms voltage applied to the motor winding without FWM
+disp(Vab1,'The rms voltage applied to the motor winding without FWM in volts is')
diff --git a/3811/CH3/EX3.14/Ex3_14.jpg b/3811/CH3/EX3.14/Ex3_14.jpg
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diff --git a/3811/CH3/EX3.14/Ex3_14.sce b/3811/CH3/EX3.14/Ex3_14.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.14
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vs=110; //source voltage in volts
+Vdc=150; //DC voltage in volts
+Vm=Vs*2^(1/2); //maximum voltage in volts
+a=90; //triggering angle in degree
+R=1; //resistance in ohm
+theta=asind(Vdc/Vm);
+theta1=75; //approximated value of theta in degree
+B=180-theta1; //The value of bete
+gama=B-a; //conduction period in degree
+VRrms=((Vdc^(2)*gama/180)+((Vm^(2)/(2*%pi))*(gama*(%pi/180)-(sind(2*B)-sind(2*a))/2)-((2*Vdc*Vm)/%pi)*(cosd(a)-cosd(B))))^(1/2);
+Icrms=VRrms/R; //rms current
+mprintf("\nThe rms current delivered to the battery during charging is %f ampere",Icrms)
+mprintf("\nTo find the power delivered to the battery during charging:")
+a1=((Vm/(R*%pi))*(((1-cosd(2*B))/2)-((1-cosd(2*a))/2)))-(((2*Vdc)/(R*%pi))*(sind(B)-sind(a)));
+b1=((Vm/(R*%pi))*(gama*(%pi/180)+((sind(2*a)-sind(2*B))/2)))-(((2*Vdc)/(R*%pi))*(cosd(a)-cosd(B)));
+pie1=atand(a1/b1);
+I1crms=sqrt(a1^2+b1^2)/sqrt(2);
+Ps=Vs*I1crms*cosd(pie1);
+Ploss=Icrms*R;
+Pcharge=Ps-Ploss;
+mprintf("\nThe power delivered to the battery during charging is %f degree",Pcharge)
diff --git a/3811/CH3/EX3.15/Ex3_15.jpg b/3811/CH3/EX3.15/Ex3_15.jpg
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diff --git a/3811/CH3/EX3.15/Ex3_15.sce b/3811/CH3/EX3.15/Ex3_15.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.15
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vs=110;//source voltage in volts
+Vdc=150;//DC voltage in volts
+Vm=Vs*2^(1/2);//maximum voltage in volts
+alphamin=0;//triggering angle in degree
+R=1;//resistance in ohm
+Beta=180;//The value of bete
+gama=Beta-alphamin;//conduction period in degree
+VRrms=sqrt(Vdc^(2)+((Vs*2^(1/2))^(2)/2)-((4*Vdc*Vm)/%pi));
+VRrms=ceil(VRrms)
+Idrms=VRrms/R;
+mprintf("\nThe total rms current during discharging is %f A",Idrms)
+a1=((Vm/(R*%pi))*(((1-cosd(2*Beta))/2)-((1-cosd(2*alphamin))/2)))-(((2*Vdc)/(R*%pi))*(sind(Beta)-sind(alphamin)));
+b1=((4*Vdc)/(R*%pi))-(Vm/R);
+pie1=atand(a1/b1);
+I1drms=sqrt((a1^2+b1^2)/2);//rms value of fundamental component
+Pac=Vs*I1drms*cosd(pie1);
+Pac=Pac*10^(-3);
+mprintf("\nThe power delivered to the ac source during discharging is %f kW",Pac)
diff --git a/3811/CH3/EX3.16/Ex3_16.jpg b/3811/CH3/EX3.16/Ex3_16.jpg
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diff --git a/3811/CH3/EX3.16/Ex3_16.sce b/3811/CH3/EX3.16/Ex3_16.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.16
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vdc=250;
+Vs=208;//line to line ac voltage
+R=3;//system resistance between battery bank and source in ohm
+Beta=122;
+Vmax=(sqrt(2)*Vs)/sqrt(3);
+mprintf("\na.To calculate minimum triggering angle and associated conduction period:")
+alphamin=60-asind(Vdc/(sqrt(3)*Vmax));
+alphamin=ceil(alphamin);
+gama=Beta-alphamin;
+mprintf("\nThe minimum triggering angle is %d degree and the associated time period is %d degree",alphamin,gama)
+mprintf("\nTo compute the average charging current for the minimum triggering angle:")
+VR=Vdc+(((9*Vmax)/(2*%pi))*cosd(alphamin+150));
+l=((9*Vmax)/(2*%pi))*cosd(alphamin+150);
+IRave=VR/R;
+mprintf("\nThe average charging current of minimum triggering angle is %f A",IRave)
+//The answers vary due to round off error
diff --git a/3811/CH3/EX3.2/Ex3_2.jpg b/3811/CH3/EX3.2/Ex3_2.jpg
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter3
+//example 3.2
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vsrms=110; //source voltage of the circuit in volts
+Vm=Vsrms*(2)^(1/2); //maximum voltage in volts
+R=2; //resistance in ohm
+alpha1=45; //triggering angle in degree
+alpha2=90; //triggering angle in degree
+//when a1=45
+disp('case 1')
+Vrms=(Vsrms/(2)^(1/2))*(1-(alpha1*(%pi/180)/%pi)+(sind(2*alpha1)/(2*%pi)))^(1/2);
+disp(Vrms,'rms voltage across the load resistance in volt is:')
+Irms=Vrms/R ;
+disp(Irms,'rms current of the resistance in ampere is:')
+Vscr=-(Vm/(2*%pi))*(1+cosd(alpha1));
+disp(Vscr,'average voltage drop across the SCR in volt is:')
+//when a2=90
+disp('case 2')
+Vrms1=(Vsrms/(2)^(1/2))*(1-(alpha2*(%pi/180)/%pi)+(sind(2*alpha2)/(2*%pi)))^(1/2);
+disp(Vrms1,'rms voltage across the load resistance in volt is:')
+Irms1=Vrms1/R ;
+disp(Irms1,'rms current of the resistance in ampere is:')
+Vscr1=-(Vm/(2*%pi))*(1+cosd(alpha2));
+disp(Vscr1,'average voltage drop across the SCR in volt is:')
diff --git a/3811/CH3/EX3.3/Ex3_3.jpg b/3811/CH3/EX3.3/Ex3_3.jpg
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.3
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vrms=110; //The voltage on the ac side in volts
+R=10; //Resistance value of the resistive load in ohm
+alpha=60; //triggering angle of the converter in degree
+Vm=110*(2)^(1/2); //maximum voltage in volts
+disp('Instantaneous power method:')
+P=((Vm)^(2)/(8*%pi*R))*(2*(%pi-alpha*(%pi/180))+sind(2*alpha));
+disp(P,'Power dissipated in the load resistance in watt is:')
+disp('Harmonic method:')
+a1=(Vm/(2*%pi*R))*(cosd(2*alpha)-1);
+b1=(Vm/(4*%pi*R))*(sind(2*alpha)+(2*(%pi-alpha*(%pi/180))));
+c1=(a1^(2)+b1^(2))^(1/2);
+pie1=atand(a1/b1);
+P1=(Vm*c1*cosd(pie1))/2;
+disp(P1,'The power computed by harmonic method in watt is:')
+
diff --git a/3811/CH3/EX3.4/Ex3_4.jpg b/3811/CH3/EX3.4/Ex3_4.jpg
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.4
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vrms=110; //The voltage on the ac side in volts
+R=10; //Resistance value of the resistive load in ohm
+alpha=60; //triggering angle of the converter in degree
+Vm=110*(2)^(1/2); //maximum voltage in volts
+a1=(Vm/(2*%pi*R))*(cosd(2*alpha)-1);
+b1=(Vm/(4*%pi*R))*(sind(2*alpha)+(2*(%pi-alpha*(%pi/180))));
+c1=(a1^(2)+b1^(2))^(1/2);
+pie1=atand(a1/b1);
+pie1=abs(pie1);
+I1rms=c1/sqrt(2);
+Irms=(Vrms/R)*sqrt(1-((alpha/%pi)*(%pi/180))+(sin(2*alpha)/(2*%pi)));
+pf=(I1rms/Irms)*cos(pie1);
+disp(pf,'The power factor on the ac side is')
+//The answers vary due to round off error
diff --git a/3811/CH3/EX3.5/Ex3_5.jpg b/3811/CH3/EX3.5/Ex3_5.jpg
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diff --git a/3811/CH3/EX3.5/Ex3_5.sce b/3811/CH3/EX3.5/Ex3_5.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.5
+//edition 1
+//publishing place:Thomson Learning
+clc;
+clear;
+Vsrms=110;//The voltage on the ac side in volts
+R=5;//Resistance value of the resistive load in ohm
+Vrms=55;//voltage across the load
+//iteration method
+xold=1;//assumed value
+x=(180/%pi)*(2.25+(sind(2*xold)/2));
+err=100;//assumed value
+while(err>0.0001)
+ xnew=(180/%pi)*(2.25+(sind(2*x)/2));
+ x=xnew;
+ err=abs(xnew-xold);
+ xold=x;
+ end
+disp(x,'The triggering angle in degree is')
+P=(Vrms)^2/R;
+disp(P,'The load power in watt is:')
+//The answer given in the book is wrong
diff --git a/3811/CH3/EX3.6/Ex3_6.jpg b/3811/CH3/EX3.6/Ex3_6.jpg
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diff --git a/3811/CH3/EX3.6/Ex3_6.sce b/3811/CH3/EX3.6/Ex3_6.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.6
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+R=10;//resistance of the load in ohm
+L=0.03;//inductance in H
+Vrms=100;//source voltage in volt
+f=60;//frequency in Hz
+alpha=60;//triggering angle in degree
+omega=2*%pi*f;
+tau=L/R;
+Q=atand((omega*L)/R);
+//iteration method
+xold=1;//assumed value
+x=Q+asind(sind(Q-alpha)*exp((-1)*(((xold-alpha)*(%pi/180))/(omega*tau))));
+err=10;//assumed value
+while(err>0.01)
+ xnew=Q+asind(sind(Q-alpha)*exp((-1)*((x-alpha)*(%pi/180)/(omega*tau))));
+ x=xnew;
+ err=abs(xnew-xold);
+ xold=x;
+ end
+disp(x,'The value of beta in degree is')
+r=x-alpha;
+disp(r,'The conduction period in degree is ')
+//The answer given in the book is wrong.While using the book answer both LHS and RHS are not equal.
diff --git a/3811/CH3/EX3.7/Ex3_7.jpg b/3811/CH3/EX3.7/Ex3_7.jpg
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diff --git a/3811/CH3/EX3.7/Ex3_7.sce b/3811/CH3/EX3.7/Ex3_7.sce
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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.7
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vs=110;//source voltage in volts
+L=20e-3;//inductance of the circuit in henry
+R=10;//resistance of the circuit in ohm
+a=60;//trigerring angle in degree
+r1=a*(%pi/180);
+Vm=Vs*2^(1/2);
+T=L/R;//Time constant of the circuit in sec
+w=2*%pi*a;//rotational speed in rad/sec
+mprintf("\n To find Conduction period:")
+b=(%pi-(w*T*log(0.05)))*(180/%pi);
+gama=b-a;//conduction period in degree
+mprintf("\nThe conduction period is %d dgree",gama)
+mprintf("\nTo find maximum diode current:")
+Z=sqrt(R^2+(w*L)^2);
+wtau=(w*L)/R;
+Q=atand(wtau);
+l=exp((-1)*((%pi-(a*(%pi/180)))/wtau));
+c=(%pi-(a*(%pi/180)));
+id=(Vm/Z)*(sind(Q)+((sind(Q-a))*l));
+mprintf("\nThe maximum diode current is %f ampere",id)
+mprintf("\nTo calculate average current of the diode:")
+Idave=(id/(2*%pi))*(-wtau)*(exp((-1)*(b*(%pi/180)-%pi))-1);
+mprintf("\nThe average current of the diode is %f ampere",Idave)
+mprintf("\nTo calculate average load current:")
+Vave=(Vm/(2*%pi))*(1+(cosd(a)));
+Iave=Vave/R;
+mprintf("\nThe average load current is %f ampere",Iave)
+mprintf("\nTo calculate average current of the SCR:")
+ISCR=Iave-Idave;
+mprintf("\nThe average current of the SCR is %f ampere",ISCR)
diff --git a/3811/CH3/EX3.8/Ex3_8.jpg b/3811/CH3/EX3.8/Ex3_8.jpg
new file mode 100644
index 000000000..ab1f1052f
--- /dev/null
+++ b/3811/CH3/EX3.8/Ex3_8.jpg
Binary files differ
diff --git a/3811/CH3/EX3.8/Ex3_8.sce b/3811/CH3/EX3.8/Ex3_8.sce
new file mode 100644
index 000000000..0dbe554c8
--- /dev/null
+++ b/3811/CH3/EX3.8/Ex3_8.sce
@@ -0,0 +1,28 @@
+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.8
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vab=208;//source voltage in volts
+Vs=Vab/3^(1/2);//rms voltage in volts
+Vm=Vs*2^(1/2);//maximum peak voltage in volts
+R=10;//resistance of the circuit in ohm
+a1=80;//triggering angle 1 in degree
+a2=30;//triggering angle 2 in degree
+if a1<60 then
+ disp(a1,'The current is discontinous')
+else if (a2>60)
+ disp(a2,'The current is discontinous')
+end
+disp('To find the power delivered at a1=80 degree:')
+B1=180;
+p=(((3*Vm^(2))/(8*%pi*10))*(2*(B1-a1)*(%pi/180)+sind(2*a1)-sind(2*B1)));//power delivered when triggering angle a1=180 degree
+P=p*10^-3;//power interms of kilowatt
+disp(P,'The power delivered at the triggering angle 80 degree in kilowatt is')
+disp('To find the power delivered at a2=30 degree:')
+B2=120+a2;
+p1=(((3*Vm^(2))/(8*%pi*10))*(2*(B2-a2)*(%pi/180)+sind(2*a2)-sind(2*B2)));//power delivered when triggering angle a2=30 degree
+P1=p1*10^-3;//power interms of kilowatt
+disp(P1,'The power delivered at the triggering angle 80 degree in kilowatt is')
diff --git a/3811/CH3/EX3.9/Ex3_9.jpg b/3811/CH3/EX3.9/Ex3_9.jpg
new file mode 100644
index 000000000..a89e1b7f1
--- /dev/null
+++ b/3811/CH3/EX3.9/Ex3_9.jpg
Binary files differ
diff --git a/3811/CH3/EX3.9/Ex3_9.sce b/3811/CH3/EX3.9/Ex3_9.sce
new file mode 100644
index 000000000..73d716810
--- /dev/null
+++ b/3811/CH3/EX3.9/Ex3_9.sce
@@ -0,0 +1,29 @@
+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 3
+//example 3.9
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vab=208;//source voltage in volts
+Vs=Vab/3^(1/2);//rms voltage in volts
+Vm=Vs*2^(1/2);//maximum peak voltage in volts
+disp('a)To find maximum average voltage across the load:')
+Vavemax=(3*3^(1/2)*Vm)/%pi;
+disp(Vavemax,'maximum average voltage across the load')
+disp('b)To find the triggering angle at the average voltage of the load:')
+xold=1;//assumed value
+c=30;//constant value
+x=asind((%pi/(3*sqrt(3)))-(cosd(xold+c)));
+err=100;//assumed value
+while(err>0.0001)
+ xnew=asind((%pi/(3*sqrt(3)))-(cosd(x+c)));
+ x=xnew;
+ err=abs(xnew-xold);
+ xold=x;
+ end
+disp(x,'The triggering angle in degree is')
+disp('c)To find load voltage when the triggering angle is -30 degree :')
+Vave=(3*3^(1/2)*Vm)/(2*%pi);
+disp(Vave,'Load voltage when the triggering angle is -30 degree in volt is')
+//The part (b) answer given in the book is wrong