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Power Electronics Lab Manual 1
TABLE OF LAB EXPERIMENTS
Sr.
No.
Experiment PageNo.
1 Single Phase uncontrolled Rectifier
i) Practically analyze the working and performance of singlephase rectifier.
4
2 Single Phase uncontrolled Rectifieri) Observe the effect of inductive load on working of a rectifier.ii) Use of a free wheeling diode.
8
3 Single Phase uncontrolled Rectifieri) Analysis of a full-wave bridge rectifier with RL load.
13
4 Half wave rectifier using R-Triggeringi) To analyze the resistive firing/triggering of silicon controlled
rectifier.
16
5 Half wave rectifier using RC Triggering
i) To analyze RC-firing Triggering network of silicon controlledrectifier.
23
6 Half wave rectifier using RC Triggering(Part Two)
i) To analyze RC-firing Triggering network of silicon controlledrectifier.
33
7 Full wave rectifier using resistive Triggering
i)
To analyze full wave R-firing network os SCR.
43
8 Full wave rectifier using RC Triggering.i) To analyze full wave RC-firing network os SCR.
51
9 TRIAC Characteristicsi) To study the V-I characteristics of a TRIAC in both directions
59
10 MOSFET Characteristicsi) To study the characteristics of MOSFET.
67
11 IGBT Characteristicsi)To study the characteristics of IGBT.
73
12 PWM generation for inverter circuits using 555 timers and 741 operationalamplifier-Natural Sampling Technique.
i)
To become familiar with pulse width modulation for operatingInverter circuits.
ii) Variation of duty cycle by comparing saw tooth waveform withConstant value.
iii)To study the operation of N-channel MOSFET operated usingPWM train.
77
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Power Electronics Lab Manual 2
PREFACE
The laboratory of each and every subject taught in the degree of Bachelors in Electrical
Engineering is of very much importance in every University. Fully equipped laboratory meeting
the industrial demands under the supervision of qualified, talented and practically motivated lab
assistants and lab engineers is also a basic criterion of the Pakistan Engineering Council. This
Manual has been formulated considering all these above mentioned points.
With Regards
Engr. Hafiz Sikandar
.
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Power Electronics Lab Manual 3
General Lab Instructions
Each student group consists of a maximum of 2-4 students. Each group member is
responsible in submitting lab report upon completion of each experiment on their
practical Note book.
Students are to wear proper attire i.e shoe or sandal instead of slipper. Excessive
jewelleries are not advisable as they might cause electrical shock.
A permanent record in ink of observations as well as results should be maintained by
each student and enclosed with the report.
The commands and observations from the simulator need to be approvedand signed
by the lab instructorupon completion of each experiment.
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Power Electronics Lab Manual 4
Name
Reg. No
Marks / Grade
Experiment No.1
Single Phase uncontrolled Rectifier
Objective :
i) Practically analyze the networking and the performance of a single phase rectifier
Equipment :
AC supply ,a diode(1N4007) ,resistor(1k),Oscilloscope, DMM, connecting wires
Arrange the circuit as shown in figure 1.
Procedure:
1. Adjust the supply voltage as used in design procedure. Recommended is 10 peak voltage
at frequency of 50 HZ.
2. Arrange the circuit as shown in figure.
3. Record your observations and calculations in tabular form and also plot the waveforms
observed on oscilloscope.
4. Compare the practical output voltage with theoretical output voltage.
V1
Vp
50 Hz
0
D1
1N4007
R1
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Power Electronics Lab Manual 5
Performance parameters :
1. Peak output voltage =Vm=------------
2. Average value of output voltage =Vdc=0.318*Vm=--------------
3. RMS value of output voltage =Vrms=0.5* Vm=---------------
4.
RMS value of output current =Irms=Vrms/R=------------------
5. Output DC power =Pdc=Vdc*Idc=--------------------
6. Output AC power =Pac =Vrms*Irms=-----------------
7. Secondary RMS voltage of Transformer or the Source=Vs=--------------
8. Secondary RMS current of Transformer or the Source=Irms=--------------
9.
Secondary AC power supplied by Transformer or the Source=Ps= Irms*Vs=--------------
10.Peak Secondary current of Transformer or the Source=Im=Vm/R=--------------
Evaluate the following parameter (also write down the required formulae) :
1. Rectifier efficiency = =-----------------------
2. Form factor=-------------------
3.
Ripple factor=------------------4. Transformer or source utilization factor(TUF)=--------------
5. Crest factor(CF) of input current i=---------------
6. Input power factor=--------------
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Power Electronics Lab Manual 6
Observe V0 on the oscilloscope and sketch it on a graph paper
Sketched input voltage:
Sketched output voltage:
Sketched voltage across the diode:
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Power Electronics Lab Manual 7
Comment :
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Power Electronics Lab Manual 8
Name
Reg. No
Marks / Grade
Experiment No.2
Single Phase uncontrolled Rectifier
Objective :
i) Observe the effect of inductive load on working of a rectifier.
ii) Use of a free wheeling diode.
Equipment :
AC supply ,a diode(1N4007) , a bridge ,resistors(1k), inductor coil(10mH)Oscilloscope, DMM, connecting wires.
Arrange the circuit as shown in figure 2.an inductive load is added to circuit .
Procedure:
1.
Adjust the supply voltage as used in design procedure. Recommended is peak voltage at
frequency of 50 HZ.
2. Arrange the circuit as shown in figure.
3. Record your observations and calculations in tabular form and also plot the waveforms
observed on oscilloscope.
4. Compare the practical output voltage with theoretical output voltage.
V1
Vp
50 Hz
0
D1
1N4007R1
L1
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Power Electronics Lab Manual 9
Performance parameters :
1. Peak output voltage =Vm=------------
2. Average value of output voltage =Vdc=0.318*Vm=--------------
3. RMS value of output voltage =Vrms=0.5* Vm=---------------
4.
RMS value of output current =Irms=Vrms/R=------------------
5. Output DC power =Pdc=Vdc*Idc=--------------------
6. Output AC power =Pac =Vrms*Irms=-----------------
7. Secondary RMS voltage of Transformer or the Source=Vs=--------------
8. Secondary RMS current of Transformer or the Source=Irms=--------------
9.
Secondary AC power supplied by Transformer or the Source=Ps= Irms*Vs=--------------
10.Peak Secondary current of Transformer or the Source=Im=Vm/R=--------------
Evaluate the following parameter (also write down the required formulae) :
1. Rectifier efficiency = =-----------------------
2. Form factor=-------------------
3.
Ripple factor=------------------4. Transformer or source utilization factor(TUF)=--------------
5. Crest factor(CF) of input current i=---------------
6. Input power factor=--------------
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Power Electronics Lab Manual 11
Section ii:
Use of a free-wheeling diode:
Arrange the circuit as shown in figure 3.a free-wheeling diode is added to circuit .
Observe V0and I on the oscilloscope and sketch them on a graph.
Sketch the output voltage:
Sketch voltage with RL load:
V1
Vp
50 Hz
0
D1
1N4007R1
L1
Dm1N4007
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Power Electronics Lab Manual 12
Sketch voltage across free-wheeling diode:
Comment :
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Using signal generator supply apply the voltage at high frequency to a half wave diode rectifier
and observe the response with resistive load and sketch output voltage.
Comment on the response at high frequency.
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Power Electronics Lab Manual 13
Name
Reg. No
Marks / Grade
Experiment No.3
Single Phase uncontrolled Rectifier
Objective :
i) Analysis of a full-wave bridge rectifier with RL load
Equipment :
AC supply , a bridge ,resistors(1k), inductor coil.(10mH) Oscilloscope, DMM,
connecting wires
Arrange the circuit as shown in figure 4.an inductive load is added to circuit .
Procedure:
1. Adjust the supply voltage as used in design procedure. Recommended is peak voltage at
frequency of 50 HZ.
2. Arrange the circuit as shown in figure.
3.
Record your observations and calculations in tabular form and also plot the waveforms
observed on oscilloscope.
4. Compare the practical output voltage with theoretical output voltage.
R1
L1
V1
Vp
50 Hz
0
D11N4007
D21N4007
D31N4007
D41N4007
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Power Electronics Lab Manual 14
Performance parameters :
1. Peak output voltage =Vm=------------
2. Average value of output voltage =Vdc=0.318*Vm=--------------
3. RMS value of output voltage =Vrms=0.5* Vm=---------------
4.
RMS value of output current =Irms=Vrms/R=------------------
5. Output DC power =Pdc=Vdc*Idc=--------------------
6. Output AC power =Pac =Vrms*Irms=-----------------
7. Secondary RMS voltage of Transformer or the Source=Vs=--------------
8. Secondary RMS current of Transformer or the Source=Irms=--------------
9.
Secondary AC power supplied by Transformer or the Source=Ps= Irms*Vs=-------------
10.Peak Secondary current of Transformer or the Source=Im=Vm/R=--------------
Evaluate the following parameter (also write down the required formulae) :
1. Rectifier efficiency = -----------------------
2. Form factor=-------------------
3. Ripple factor=------------------
4. Transformer or source utilization factor(TUF)=--------------
5.
Crest factor(CF) of input current i=---------------
6. Input power factor=--------------
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Power Electronics Lab Manual 15
Observe V0and I on the oscilloscope and sketch them on a graph.
Sketch the output voltage with resistive load:
Sketch voltage with RL load:
Comment :
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Power Electronics Lab Manual 16
Name
Reg. No
Marks / Grade
Experiment No.4
Half wave rectifier using R-Triggering
Objective:
i)
To analyze resistive firing/triggerimg silicon controlled rectifier(SCR).
Equipment :
AC Supply, SCR(MCR100-6),a diode, load resistor of designed value, variable gate
resistance(0-100K).
Half wave Rectifier using R-triggering:
Design problems:
Minimum resistance (Rmin):
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Power Electronics Lab Manual 17
the minimum resistance Rmin should be such that when Rg=0,the gate current does not exceed
the maximum allowable value,
Rmin=Vs/Ig(max) ----------------(1)
Vs(max)= -------------(It is equal to max. voltage supplied by the Ac supply)
Ig(max)= --------------(the max. gate current is usually given by Igt in the datasheet)
Using equation (1):Rmin= ------------(choose the nearest standard resistor)
The value of selected standard resistor =Rmin= --------------------
Gate Resistance (Rg):
The min.value of gate triggering current is selected as specified in datasheet(80uAin case of
MCR 100-6)the SCR will turn on when instantaneous value of supply voltage Vs becomes equal
to:
Vs>- to Ig (min.)[Rg+Rmin]+Vg(min.)+VD -----------------(2)
Rg+Rmin.
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Power Electronics Lab Manual 18
Procedure:
1. Adjust the supply voltage as used in design procedure. Recommended is 15Vpeak at
frequency of 50 HZ.
2. Arrange the circuit as shown in figure.
3.
Keep the potentiometer resistance Rg to its max. value so Ig is very small and SCR isnot triggered. Measure and observe the voltage across load and SCR.
4. Decrease the resistance of potentiometer Rg such that SCr is now fired and almost all
the input voltage appears across the load. Measure and observe the change in voltage
across the SCR.
5. Record your observations for at least ten different firing angles over the entire range
of observations.
6. Record your observations and calculations in tabular form and also plot the
waveforms observed on oscilloscope.
7. Compare the practical output voltage with theoretical output voltage.
Observation set No.1:
No. Firing angle (a) V0(dc)
(practically using
DMM)
Vo(dc)
(theoretically
using calculations)
1
2
3
4
5
6
7
8
9
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Power Electronics Lab Manual 19
Sketch voltage waveform across load resistance for firing angle in reading 2
Sketch voltage waveform across load thyristor for firing angle used above
Sketch voltage waveform across load resistance for firing angle in reading 4
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Power Electronics Lab Manual 20
Sketch voltage waveform across load thyristor for firing angle used above
Sketch voltage waveform across load resistance for firing angle in reading 6
Sketch voltage waveform across load thyristor for firing angle used above
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Power Electronics Lab Manual 21
Sketch voltage waveform across load resistance for firing angle in reading 8
Sketch voltage waveform across load thyristor for firing angle used above
Sketch voltage waveform across load resistance for firing angle in reading 10
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Power Electronics Lab Manual 22
Sketch voltage waveform across load thyristor for firing angle used above
Show your calculations in firing angle in reading 3
Show your calculations in firing angle in reading 7
Sketch variations of output voltage with firing angle
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Power Electronics Lab Manual 23
Name
Reg. No
Marks / Grade
Experiment No.5
Half Wave Rectifier using RC-Triggering
Objective:
i) To analyze RC-firing/triggering network of silicon controlled rectifier
Equipment:
AC-supply, SCR(MCR 100-6),a diode, load resistor of designed value, variable gate
resistance(0-100kohm)
And capacitance of designed value.
HALF WAVE RECTIFIER USING R-TRIGGERING
Section 1:Half Wave rectifier using RC-Triggering
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Design Procedure:
Minimum Resistance(Rmin):
The minmum resistance Rmin shoule be such that when RG=0,the gate current does not exceed
the maximum allowable value,
Rmin=Vs(max)/ig(min)
Vs(max)=_______________(it is equal to the maximum voltage supplied by the AC supply)
Ig(max)=_______________(This maximum gate current is usually given by IGT in the
datasheet)
Using Equation (1):Rmin=_____________(choose the nearest standard resistor)
The value of the selected standard resistor=Rmin=_____________
An empirical relation for the product RC is
RC>=0.65T
T=1/f=time period of supply voltage
Gate Resitance(RG):
The minimum value of gate triggering current is selected as specifies in the datasheet(80_A in
case of MCR 100-6).The SCR will turn on when instantneous value of supply voltage Vsbecomes equal to
Vs>=IG(min)R+VG(min)+VD
R
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Power Electronics Lab Manual 25
VD=_____________(it is equal to the forward voltage drop across the diode)
IG=______________(it is the minimum value of gate current at which SCR fires)
VG=_____________(it is the gate-cathode voltage corresponding to IG(min))
Using equation (2):RG=_____________(choose the nearest standard resistor)
The value of the selected standard resistor=RG=_____________
Selction of load resistance:
Maximum value of anode to cathode from datasheet=_____________A
Latching current from datasheet=___________A
Holding current from datasheet=____________A
Choose a value of laod resitance such that anode to gate current does not exceed the rated current
and is not less than the latching current when SCR is conducting.it is recommended to selected
laod resistance such that of the rated current or less flows when SCR is conducting.(Latching
current IL is the minimum anode current required to maintain the thyristor in the On-state
immediately)after the thyristor has been turned ON and the gate signal has been removed.
Procedure:
1. Adjust the supply voltage as used in design procedure. Recommended is 15V peak at
frequency of 50Hz.
2. Arrange the circuit as shown in figure.
3. Keep the potentiometer resistance RG to its maximum value so IG is very small and SCR
is not triggered. Measure and observe the voltage across load and SCR.
4.
Describe the resistance of potentiometer RG such that SCR is now fired and almost all
the input voltage appears across the load. Measure and observe the change in voltage
across load and SCR.
5. Record your observation for at least ten different firing angles over the entire range of
observation.
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Power Electronics Lab Manual 26
6. Record your observation and calculations in tabular form and also plot the waveform
observed on oscilloscope.
7. Compare the practical output voltage with theoretical output voltage.
Observations Set
o. Firing Angle Vo(dc)
(Practically Using DMM)
Vo(dc)
(TheoraticallyUsing
DMM)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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Sketch voltage waveform across thyristor for firing angle used above
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
Sketch voltage waveform across load resistance for firing angle in reading 6
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
Sketch voltage waveform across thyristor for firing angle used above
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
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Sketch voltage waveform across load resistance for firing angle in reading 8
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
Sketch voltage waveform across thyristor for firing angle used above
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
Sketch voltage waveform across load resistance for firing angle in reading 10
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
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Sketch voltage waveform across thyristor for firing angle used above
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
Show your calculations in firing angle in reading 3
Show your calculations in firing angle in reading 7
Sketch the variation of output voltage with firing angle.
Comments:
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Sketch voltage waveform across load resistance for firing angle in reading 4
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50m
Sketch voltage waveform across thyristor for firing angle used above
0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Time
Compare two RC circuits in terms of performance
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
___________________________________________________________________________________________
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Power Electronics Lab Manual 33
Name
Reg. No
Marks / Grade
Experiment No.6
Half Wave Rectifier using RC-Triggering Part Two)
Objectives:
i) To analyze RC-firing/triggering network of silicon controlled rectifier.
Equipment:
AC-supply, SCR (MCR 100-6), a diode, load resistor of designed value, variable gate
Resistance (0-750k) and capacitors of designed value.
Half Wave Rectifier using RC-Triggering
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Power Electronics Lab Manual 34
Design Procedure:
Minimum Resistance (R min):
The minimum resistance R min should be such that when RG=0, that gate current doesnot exceed the maximum allowable value,
R min =Vs (max) / Ig (max) (1)
Vs (max) = ________________(It is equal to the maximum voltage supplied by the AC
Supply)
Ig (max) = _________________(This maximum gate current is usually given by IGT in
The datasheet.)
Using Equation (1): R min =________________(choose the nearest standard resistor)
The value of the selected standard resistor = Rmin
=____________________
An empirical relation for the product RC is
RC 0.65T
T=1/f=time period of supply voltage
Gate Resistance (RG):
The minimum value of gate triggering current is selected as specified in the datasheet
(80A
In case of MCR 100-6).The SCR will turn on when instantaneous value of supply
voltage Vs
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Becomes equal to
Vs IG (min) R + VG (min) + VD (2)
R Vs VG (min) VD / IG (min) (3)
R = RG + R min
VD =________________________ (It is equal to the forward voltage drop across the diode).
IG (min) = __________________ (It is the minimum value of gate current at which SCR fires).
VG (min) = ________________ (It is the gate-cathode voltage corresponding to IG (min)
Using Equation (2): RG = _______________________ (choose the nearest standard resistor)
The value of the selected standard resistor = RG=_____________________________
Selection of load resistance:
Maximum value of anode to cathode current from data sheet = _____________ A
Latching current from data sheet = _____________________ A
Holding current from data sheet = _______________________ A
Choose a value of load resistance such that anode to cathode current does not exceed the rated
current and is not less than the latching current when SCR is conducting. It is recommended to
Use 820 ohm as load resistance.
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Procedure:
1.Adjust the supply voltage as used in design procedure. Recommended is 10V peak at
frequencyof 50HZ.
2. Arrange the circuit as shown in figure 4a.
3. Keep the potentiometer resistance RG to its maximum value so IG is very small and SCR is
not trigged. Measure and observe the voltage across load and SCR.
4. Decrease the resistance of potentiometer RG such that SCR is now fired and almost all the
input Voltage appears across the load .Measure and observes the change in voltage across load
and SCR.
5. Record your observations for at least ten different firing angles over the entire range of
observation.
6. Record your observations and calculations in tabular form and also plot the waveform
observed on oscilloscope.
7. Compare the practical output voltage with theoretical output voltage.
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Power Electronics Lab Manual 37
Observation Table:
NO Firing Angle Vo(dc)
(Practically using DMM)
Vo(dc)
(Theoretically using
calculations)
1.
2.
3.
4.
5.
6.
7.
8.
9.
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Sketch voltage waveform across thyristor for firing angle used above:
Sketch voltage waveform across load resistance for firing angle in reading 6:
Sketch voltage waveform across thyristor for firing angle used above:
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Sketch voltage waveform across load resistance for firing angle in reading 8:
Sketch voltage waveform across thyristor for firing angle used above:
Sketch voltage waveform across load resistance for firing angle in reading 10:
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Sketch voltage waveform across thyristor for firing angle used above:
Show your calculations for voltage with firing angle in reading 3:
Show your calculations for voltage with firing angle in reading 7:
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Sketch the variation of output voltage with firing angle:
Comments:
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Power Electronics Lab Manual 43
Name
Reg. No
Marks / Grade
Experiment No. 7
Full Wave Rectifier Using Resistive Triggering
Objectives:
i) To analyze full wave R - firing network of SCR.
Equipment:
Ac supply, oscilloscope, SCR (MCR 100-6), single phase Diode Bridge, load resistor of
designed value, virile gate rsistance, connecting wires and breadboard.
Circuit diagram:
Task:
Vary the firing angle by the gate resistance from 0 to 90 degree and observe load voltage and
voltage across thyristor on the oscilloscope .sketch waveforms for selected value of firing angle.
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Design Procedure:
The design equations are same as used in experiment no 2 for half wave R-triggering.
1. Load Resistance =_____________ohms.
2. Rmin= __________ohms.
3. Gate resistance= ______________ohms.
Procedure:
1. Adjust the supply voltage as used in design procedure .recommended is 10 V peak at
frequency of 50 HZ.
2. Arrange the circuit as shown in Figure 4a.
3. Keep the potentiometer resistance Rg to its maximum value so Ig Is very small and SCR will
not triggered .Measure and observe the voltage across load and SCR.
4. Decrease the resistance of potentiometer Rg such that scr is now fired and almost all the input
voltage appears across the load .measure and observe the change in voltage across load and SCR.
5. Record your observations for at least 10 different firing angles over the entire range of
observations.
6. Record your observations and calculations in tabular form and also plot the waveforms
observed on oscilloscope.
7. Compare the practical output voltage with theoretical output voltage.
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Sketch voltage waveform across load resistance for firing angle in reading 2:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
Sketch voltage waveform across thyristor for firing angle used above:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
Sketch voltage waveform across load resistance for firing angle in reading 4:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
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Sketch voltage waveform across thyristor for angle used above:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
Sketch voltage waveform across load resistance for firing angle in reading 6:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
Sketch voltage waveform across thyristor for firing angle above:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
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Sketch voltage waveform across load resistance for firing angle in reading 8:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
Sketch voltage waveform across thyristor for firing angle used above:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
Sketch voltage waveform across load resistance for firing angle in reading 10:
0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms
Time
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Comments:
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
Performance Parameters:
Evaluate the following parameters by consulting the suggested pre-lab reading .Also consult thelab manual handout of experiment no.1 (use a separatepaper sheet if required, to record the
required observations and details of calculations):
Rectifier Efficiency= _______________________
Form Factor= __________________________
Ripple Factor= ______________________________
Transformer or Source Utilization Factor (TUF) = ___________________
Epress the output voltage (at firing angle of 30 degree) with Fourier series.
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Name
Reg. No
Marks / Grade
Experiment No.8
Full Wave Rectifier Using RC-Triggering
Objectives:
i)
To analyze full wave RC-firing network of SCR.
Equipment:
AC supply,oscilloscope,SCR(MCR-100-6),single phase diode bridge,load resistors,
variable gate resistance,capacitors,connecting wires, breadboard.
Circuit Diagram:
Task:
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Verify the firing angle (90 to 180 degree) by changing the gate resistance and observe load
voltage and voltage across thyristor on the oscilloscope.Sketch for selected values of firing
angle.
Load resistance=--------------------ohms
Gate resistance= --------------------ohms
R min=--------------------------------ohms
Capacitor=---------------------------
Procedure:
1. Adjust the supply voltages as used in design procedure.
2. Arrange the circuit as in figure.
3. Keep the potentiometer resistance RGto its maximum value so IGis very small and
SCR is not triggered.Measure and observe the voltage across load and SCR.
4. Decrease the resistance of potentiometer RGsuch that SCR is now fired and almost
All the input voltage appears across the load.Measure and observe the change in
The voltage across load and SCR.
5. Record your observations for at least ten different firing angles over the entire range
of observations.
6. Record your observations and calculations in tabular form and also plot the
Waveforms observed on oscilloscope.
7. Compare the practical output with theoretical output voltage.
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Observations Table:
V0 (DC)
Theoretically
Calculations
V0 (dc)
Using DMM
Firing Angleo.
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Sketch voltage waveform across load resistance for firing angle in reading 2.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Sketch voltage waveform across thyristor for firing angle used above.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Sketch voltage waveform across load resistance for firing angle in reading 4.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
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Sketch voltage waveform across thyristor for firing angle used above.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Sketch voltage waveform across load resistance for firing angle in reading 6.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Sketch waveform across thyristor for firing angle used above.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
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Sketch voltage waveform across thyristor for firing angle used above.
0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms
Show your calculations for voltage with firing angle in reading 3.
Show your calculations for voltage with firing angle in reading 7.
Sketch the variation of output voltage with firing angle.
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Comments:
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Performance Parameters:
Rectifier Efficiency =----------------------
Form Factor =-------------------------------
Ripple Factor =-----------------------------
Transform or source utilization factor(TUF) =------------------------
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II -mode:
1. Connections are made as shown in the circuit diagram (b)
2. The gate current is set as same value as in i-mode
3. Repeat the step no. s 3, 4, 5, 6, & 7 of I-mode
Circuit Diagram II-Mode:
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Characteristics curve:
Normal method:
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III-mode:
1. Connections are mode as shown in the circuit diagram (c).
2.
Step no. s 2, 3, 4, 5, 6, & 7 are to be repeated as in i-mode.
IV-mode:
1. Connections are mode as shown in the circuit diagram (d)
2. Repeat the step no. s2,3, 4, 5, 6, & 7 of i-mode.
Circuit Diagram For III & IV mode:
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Observations and Calculations:
I-Mode
Ig= mA
Sr.no. VTRIAC(V) ITRIAC(mA)
II-Mode
Ig= mA
Sr.no. VTRIAC(V) ITRIAC(mA)
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III-Mode
Ig= mA
Sr.no. VTRIAC(V) ITRIAC(mA)
IV-Mode
Ig= mA
Sr.no. VTRIAC(V) ITRIAC(mA)
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Comment :
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Name
Reg. No
Marks / Grade
Experiment no.10
MO SFET C harac ter is t ics
Objective:
To study the characteristics of MOSFET.
Equipment:
MOSFET-IRF840, Power Supplies, Wattage Resistors, Ammeter, Voltmeter, etc.
Circuit Diagram:
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Procedure:
Drain Characteristics
1.
Connections are made as shown in the circuit diagram.
2. Adjust the value of VGSslightly more than threshold voltage Vth
3. By varying VI , note clown ID& VDSand are tabulated in the tabular column
4. Repeat the experiment for different values of VGSand note down IDv/s VDs
5. Draw the graph of IDv/s VDSfor different values of VGS.
Transconductance Characteristics
1. Connections are made as shown in the circuit diagram.
2. Initially keep VI and V2 zero.
3. Set VDS= say 0.6 V
4. Slowly vary V2 (VGE) with a step of 0.5 volts, note clown corresponding and VDS
readings for every 0.5v and are tabulated in the tabular column.
5.
Repeat the experiment for different values of VDS& draw the graph of IDv/s VGS.
6. Plot the graph of VGSv/s ID
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Observations and Calculations.
VGS=
VDS(V) ID(mA)
VGS=
VDS(V) ID(mA)
VGS=
VDS(V) ID(mA)
VGS=
VDS(V) ID(mA)
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Comment :
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Name
Reg. No
Marks / Grade
Experiment No.11
IGBT Charac ter i s ti cs
Objective:
To study the characteristics of IGBT
Equipment:
IGBT-IRGBC 20S, Power Supplies, Wattage Resistors, Ammeter, Voltmeter, etc.
Circuit Diagram:
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Procedure:
Collector Characteristics
1.
Connections are mode as shown in the circuit diagram.
2.
Initially setV2 toVGEI= 5v (slightly more than threshold voltage)
3. Slowly vary VI and note clown Icand VCE
4. For particular value of VGEthere is pinch off voltage (VP) between collector
and emitter.
5. Repeat the experiment for different values of VGEand note down Icv/s VCE
6. Draw the graph of Icv/s VCEfor different values of VGE.
Transconductance Characteristics
1. Connections are mode as shown in the circuit diagram.
2. Initially keep VI and V2 at zero.
3. Set VCEI= say 0.8 v
4. Slowly vary V2(VGE) and note downICandVGEreadings for every 0.5v and
enter tabular column
5.
Repeat the experiment for different values of VCEand draw the graph of Ic v/s
vot
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Observations and Calculations.
VGE=
VCE(V) IC(mA)
VGE=
VCE(V) IC(mA)
VGE=
VCE(V) IC(mA)
VGE=
VCE(V) IC(mA)
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Comment :
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Name
Reg. No
Marks / Grade
Experiment No. 12
PWM generation for inverter circuit using 555 timer and 741
Operational Amplifier Natural Sampling Technique
Objective:
1.
To become familiar with pulse width modulation for operating inverter circuits2. Variation of duty cycle by comparing sawtooth waveform with constant value.
3. to study the operation of N-channel MOSFET operated using PWM train.
Equipment:
A DC power supply, bread board, N-channel MOSFET (IRF540), two general purposesswitching transistors (2N3904 and 2N396), Operational Amplifier 741, 555 timer IC,
two variable resistors (50K-ohm), resistors of required values (4.7K,10K,1K) and
capacitors (1 uF and 47 PF)
Datasheet information:
Carefully study the datasheet of different components and find out the following parameters
N-Channel MOSFET (IRF540)
Drain source voltage = __________________
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Drain Current = _______________________
Gate-Source voltage = __________________
Turn ON time = ______________________
Turn OFF time = ______________________
Transistor 2N3904
Turn ON time = ______________________
Turn OFF time = _____________________
Rated Voltage = ______________________
Rated Current = ______________________
Transistor 2N3906:
Turn ON time = __________________
Turn OFF time = _________________
Rated Voltage = __________________
Rated Current = __________________
PIN configuration of 555 timers:
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4.
Now connect 741 in comparator mode as shown in figure below
5.
Check the output voltage waveform at pin 6 of 741 and sketch the waveforms below
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6. With the help of variable resistance connected at pin 2 of 741 adjust the duty of the
output waveform equal to 50% and sketch two cycles of waveform
7.
Now sketch the waveform of step 3 and voltage at pin 2 of Op-Amp and voltagewaveform at pin 6 of 741 at same scale. (Three waveforms)
8.
What do you observe from the above waveform?
_____________________________________________________________________________________
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9. Does above waveform explain pulse width modulation ? which waveform is modulating
waveform in above waveform?
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____________________
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10.
Now connect N-Channel MOSFET circuit as shown in figure below
11.connect oscilloscope across the load resistance and sketch waveform
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12.Vary the resistance controlling the duty cycle and record different reading in ascending
order of duty cycle.
No. ON Time Duty Cycle
Ratio
Voltage at
pin 2 of
Op-Amp
Vo (dc)
(Practically
using DMM)
Vo(dc)
(Theoretically
using
Calculations)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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For observations 9 from table:
Represent the Load waveform in terms of Fourier series. (Show details)
Sketch the spectrum up to 20th
order harmonic
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What do you mean by natural sampling?
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Comments:
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How we can remove the 3rd
harmonic and its multiples from the spectrum?
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Note: On each graph clearly mention your time scale and magnitude; Plot at least two complete
cycles of waveforms else there will be zero credit. All the readings should be in sequence. Make
sure your roll number is written on each and every page of this handout. Please check the website