summaryrefslogtreecommitdiff
path: root/3731/CH7
diff options
context:
space:
mode:
Diffstat (limited to '3731/CH7')
-rw-r--r--3731/CH7/EX7.1/Ex7_1.sce57
-rw-r--r--3731/CH7/EX7.2/Ex7_2.sce53
-rw-r--r--3731/CH7/EX7.3/Ex7_3.sce105
-rw-r--r--3731/CH7/EX7.4/Ex7_4.sce60
4 files changed, 275 insertions, 0 deletions
diff --git a/3731/CH7/EX7.1/Ex7_1.sce b/3731/CH7/EX7.1/Ex7_1.sce
new file mode 100644
index 000000000..820ce94cf
--- /dev/null
+++ b/3731/CH7/EX7.1/Ex7_1.sce
@@ -0,0 +1,57 @@
+//Chapter 7:Synchronous Motor and Brushless DC Motor Drives
+//Example 1
+clc;
+
+//Variable Initialization
+
+//Ratings of the synchronous motor
+Pm1=500*1000 // power rating in W
+f=50 // frequency in HZ
+Vl=3.3*1000 // line voltage in V
+pf=0.8 // power factor lagging
+P=4 // number of poles
+I=10 // field current in A
+Xs=15 // reactance of the windings in ohm
+Rs=0 // resistance of the windings in ohm
+Wms=50*%pi // synchronous speed in rad/sec
+Pm=Pm1/2 // power at half the rated torque when the losses are neglected
+
+//Solution
+V=Vl/sqrt(3) //phase voltage
+Is=Pm1/(sqrt(3)*Vl*pf) //rated current
+rad=acos(pf)
+
+Is=Is * (cos(-rad) + sin(-rad)*%i) //rated current in vector form
+V=V * (cos(0) + sin(0)) //rated phase voltage in rectangular form
+E=V-Is*%i*Xs //back emf
+
+//(i) When field current has not changed
+sin_delta=Pm*Xs/(3*abs(V)*abs(E))
+delta=asin(sin_delta) //angle delta
+Is=(V-(abs(E) * (cos(-delta) + sin(-delta)*%i)))/(%i*Xs) //armature current
+Is1=[]
+Is1(1)=abs(Is)
+Isp=phasemag(Is)
+x=Isp
+n1=x*%pi/180
+power_factor=cos(n1) //power factor
+
+//(ii) At unity power factor and rated torque
+cos_phi=1
+Is=Pm1/(3*V) //since Pm1=3*V*Is
+E1=V-Is*%i*Xs
+If=abs(E1)/abs(E)*I //field current
+
+//(iii) At the field current of 12.5 A
+If1=12.5 //field current
+E2=If1/I*abs(E)
+Is=sqrt(E2**2-abs(V)**2)/Xs //since E2=abs(V-Is*1j*Xs)
+Pm=3*abs(V)*Is*cos_phi //power output at the given field current
+T=Pm/Wms //required torque
+
+//results
+mprintf("i)Armature current :%.2f %.1f ° A",abs(Is1),x)
+mprintf("\nPower factor:%.2f lagging",power_factor)
+mprintf("\nii)Field current at unity power factor at rated torque:%.2f A",If)
+mprintf("\niii)Required torque is:%.1f N-m",T)
+//There is a slight difference in the answer
diff --git a/3731/CH7/EX7.2/Ex7_2.sce b/3731/CH7/EX7.2/Ex7_2.sce
new file mode 100644
index 000000000..f2c3297ed
--- /dev/null
+++ b/3731/CH7/EX7.2/Ex7_2.sce
@@ -0,0 +1,53 @@
+//Chapter 7:Synchronous Motor and Brushless DC Motor Drives
+//Example 2
+clc;
+
+//Variable Initialization
+
+//Ratings of the synchronous motor is same as that of Example-7.1
+Pm1=500*1000 // power rating in W
+f=50 // frequency in HZ
+Vl=3.3*1000 // line voltage in V
+pf=0.8 // power factor lagging
+P=4 // number of poles
+I=10 // field current in A
+Xs=15 // reactance of the windings in ohm
+Rs=0 // resistance of the windings in ohm
+Pm=Pm1/2 // power at half the rated torque when the losses are neglected
+
+//Solution
+Wms=50*%pi // synchronous speed in rad/sec
+V=Vl/sqrt(3) // phase voltage
+Is=Pm1/(sqrt(3)*Vl*pf) //rated current
+rad=acos(pf)
+
+Is=Is * (cos(-rad) + sin(-rad)*%i) //rated current in vector form
+V=V * (cos(0) + sin(0)) //rated phase voltage in rectangular form
+E=V-Is*%i*Xs //back emf
+
+//(i) at rated current and unity power factor
+E1=V-abs(Is)*%i*Xs
+delta=phasemag(E1) //phase angle of E1
+nd=delta*%pi/180
+Pm=3*abs(V)*abs(E1)*sin(nd)/Xs //mechanical power developed
+T=Pm/Wms //braking torque
+If=abs(E1)/abs(E)*I //field current
+
+//(ii) at field current of 15A and 500kW output
+If1=15 //field current
+Pm=-500*1000 //output power
+E2=If1/I*abs(E)
+sin_delta=Pm*Xs/(3*abs(V)*abs(E2))
+delta=asin(sin_delta) //angle delta
+Is=((E2*(cos(abs(delta))+sin(abs(delta))*%i))-V)/(%i*Xs) //armature current
+Isn=phasemag(Is)
+x=(Isn)*%pi/180 //phase angle of Is
+power_factor=cos(x) //power factor
+
+
+//Results
+mprintf("i)Braking torque :%.1f N-m",T)
+mprintf("\nField current:%.2f A",If)
+mprintf("\nii)Armature current :%.2f %.2f ° A",abs(Is),Isn)
+mprintf("\nPower factor:%.3f lagging",power_factor)
+//Note :There is a slight difference in the answers
diff --git a/3731/CH7/EX7.3/Ex7_3.sce b/3731/CH7/EX7.3/Ex7_3.sce
new file mode 100644
index 000000000..66b494658
--- /dev/null
+++ b/3731/CH7/EX7.3/Ex7_3.sce
@@ -0,0 +1,105 @@
+//Chapter 7:Synchronous Motor and Brushless DC Motor Drives
+//Example 3
+clc;
+
+//Variable Initialization
+
+//Ratings of the synchronous motor
+Pm1=6*10**6 // power rating in W
+f=50 // frequency in HZ
+Vl=11*1000 // line voltage in V
+pf=0.9 // power factor leading
+P=6 // number of poles
+I=10 // rated field current in A
+Xs=9 // reactance of the windings in ohm
+Rs=0 // resistance of the windings in ohm
+N=120*f/P // synchronous speed
+
+//Solution
+V=Vl/sqrt(3) //phase voltage
+Is=Pm1/(sqrt(3)*Vl*pf) //rated current
+rad=acos(pf)
+
+//(i)To find torque and field current at rated armature current
+// at 750 rpm and 0.8 leading power factor
+Is=Is * (cos(rad) + sin(rad)*%i) //rated current in vector form
+V=V *(cos(0)+sin(0)*%i)
+E=V-Is*%i*Xs //back emf
+
+N1=750 //speeed in rpm
+pf1=0.8 //given leading power factor
+f1=N1/N*f //required frequency
+V1=abs(V)*f1/f //required voltage
+Xs1=Xs*f1/f //required field resistance
+E1=V1-Xs1*%i*(abs(Is) * (cos(acos(pf1))+sin(acos(pf1))*%i)) //rated back emf in complex form
+E1_polar=abs(E1) //rated back emf in rectangular form
+
+//At rated field current and 750 rpm
+E2=abs(E)*N1/N //back emf at the given speed N1
+If=abs(E1)/E2*f //field current at the given speed N1
+Pm=3*abs(V1)*abs(Is)*pf1 //power input at the given speed N1
+Wm1=2*%pi*N1/60 //angular motor speed in rad/s
+T=Pm/Wm1
+
+//(ii) At half the rated motor torque and 1500 rpm and rated field current
+Pm=6*10**6 //rated power rating in W
+N1=1500 //speeed in rpm
+f1=N1/N*f //required frequency
+Xs1=f1/f*Xs //required field resistance
+E1=abs(E)*f1/f //back emf at rated field current
+
+
+Wms=Pm
+Wms_=N1/N*Wms
+Pm_= (0.5)*Wms_ //required power developed at N1=1500 rpm
+
+sin_delta=Pm_*Xs1/(3*abs(V)*abs(E1)) //since Pm=3*abs(V)*abs(E1)*sin(delta)/Xs
+delta=asin(sin_delta) //angle delta
+Is=(abs(V)-(E1 * (cos(-delta)+sin(-delta)*%i)))/(%i*Xs1) //armature current
+Is1=polar(Is) //aramture current in rectangular form
+x1=phasemag(Is)
+x1n=x1*%pi/180
+power_factor1=cos(x1n) //power factor
+
+//(iii) at 750 rpm and rated field current from part(i)
+N1=750 //speeed in rpm
+pf1=0.8 //given leading power factor
+f1=N1/N*f //required frequency at N1=750 rpm
+V1=abs(V)*f1/f //required voltage at N1=750 rpm
+Xs1=Xs*f1/f //required field resistance
+E2=abs(E)*N1/N
+
+Pm=-4.2*10**6 //braking power output
+sin_delta=Pm*Xs1/(3*abs(V1)*abs(E2)) //since Pm=3*abs(V)*abs(E1)*math.sin(delta)/Xs
+delta=asin(sin_delta) //angle delta
+Is=(E2 * (cos(abs(delta))+sin(abs(delta))*%i)-V1)/(%i*Xs1) //armature current
+Is2=polar(Is) //aramture current in rectangular form
+x2=phasemag(Is)
+x2n=x2*%pi/180
+power_factor2=cos(x2n) //power factor
+
+//(iv)from part (ii) at 1500 rpm and from part(iii) the armature current of 349.9 A is taken
+Is=Pm1/(sqrt(3)*Vl*pf) //armature current as given from (i)
+N1=1500 //speeed in rpm
+f1=N1/N*f //required frequency at N1=1500 rpm
+Xs1=f1/f*Xs //required field resistance
+E1=abs(E)*f1/f //at rated field current
+E2=V-%i*Xs1*Is
+E2ph=abs(E2)
+E2n=phasemag(E2)
+E2na=E2n*%pi/180
+If1=abs(E2ph)/abs(E1)*f //required field current
+Pm=3*abs(V)*(E2ph)*sin(abs(E2na))/Xs1 //power input
+Wm1=2*%pi*N1/60 //motor speed in rad/sec
+T1=Pm/Wm1
+
+//Results
+mprintf("\ni)Required torque is:%.1f N-m",T)
+mprintf("\nField current :%.2f A",If)
+mprintf("\nii)Armature current :%.1f %.2f ° A",abs(Is1),x1)
+mprintf(" \nPower factor :%.1f leading",power_factor1)
+mprintf("\niii)Armature current :%.2f %.2f ° A",abs(Is2),x2)
+mprintf("\nPower factor :%.3f lagging",power_factor2)
+mprintf("\niv)Field current :%.2f A",If1)
+mprintf("\nRequired torque is:%.1f N-m",T1)
+//There is a slight difference in the answers
diff --git a/3731/CH7/EX7.4/Ex7_4.sce b/3731/CH7/EX7.4/Ex7_4.sce
new file mode 100644
index 000000000..ac8a39994
--- /dev/null
+++ b/3731/CH7/EX7.4/Ex7_4.sce
@@ -0,0 +1,60 @@
+//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
generated by cgit (git 2.34.1) at 2024-12-19 12:37:51 +0000