POWER ELECTRONICSAND SIMULATION LAB
3rd YEAR-II SEMESTER
NAME OF THE STUDENT
:
REGISTERNUMBER
:
YEAR/ SEMESTER
:
STAFF INCHARGE
: Mr. G.SRIDHAR BABU Assoc.Prof/EEE
1
General Instructions to students for EEE Lab courses
 Be punctual to the lab class.
 Attend the laboratory classes wearing the prescribed uniform and shoes.
 Avoid wearing any metallic rings, straps or bangles as they are likely to prove dangerous at
times.
 Girls should put their plait inside their overcoat
 Boys students should tuck in their uniform to avoid the loose cloth getting into contact with
rotating machines.
 Acquire a good knowledge of the surrounding of your worktable. Know where the various
live points are situated in your table.
 In case of any unwanted things happening, immediately switch off the mains in the
worktable.
 This must be done when there is a power break during the experiment being carried out.
 Before entering into the lab class, you must be well prepared for the experiment that you
are going to do on that day.
 Get the circuit diagram approved.
 Prepare the list of equipments and components required for the experiment and get the
indent approved.
 Make connections as per the approved circuit diagram and get the same verified.
After getting the approval only supply must be switched on.
 Get the reading verified. Then inform the technician so that supply to the worktable can be
switched off.
 You must get the observation note corrected within two days from the date of completion
of experiment. Write the answer for all the discussion questions in the observation note. If
not, marks for concerned observation will be proportionately reduced.
 Submit the record note book for the experiment completed in the next class.
 If you miss any practical class due to unavoidable reasons, intimate the staff in charge and
do the missed experiment in the repetition class.
 Such of those students who fail to put in a minimum of 75% attendance in the laboratory
class will run the risk of not being allowed for the University Practical Examination.
2
LIST OF EXPERIMENTS
Any eight of the experiments in power electronics lab
1. Study of characteristics of SCR, MOSFET, & IGBT.
2. Gate firing circuit for SCR’s.
3. Single phase AC voltage controller with R AND RL loads.
4. Single phase fully controlled bridge converter with R load and RL loads
5. Forced commutation circuits (Class A, Class B, Class C, Class D & Class E).
6. DC Jones chopper with R and RL loads.
7. Single phase parallel inverter with R and RL loads.
8. Single phase cycloconverter with R and RL loads.
9. Single phase half controlled converter with R loads.
10. Three phase half controlled bridge converter with R loads.
11. Single phase series inverter with R and RL loads.
12. Single phase bridge converter with R and Rl loads.
13. Single phase dual converter with RL loads.
14. Operation of MOSFET based chopper.
Any two simulation experiments with PSPICE/PSIM
15. PSPICE simulation of single phase full converter using RLE loads and single phase
AC voltage controller using RLE loads.
16. PSPICE simulation of resonant pulse commutation circuit and buck chopper.
17. PSPICE simulation of single phase inverter with PWM control.
3
LIST OF CYCLE-I
1. Single phase AC voltage controller with R AND RL loads.
2. DC Jones chopper with R and RL loads.
3. Single phase parallel inverter with R and RL loads.
4. Single phase half controlled converter with R loads.
5. PSPICE simulation of single phase full converter using RLE loads and single phase
AC voltage controller using RLE loads.
LIST OF CYCLE-II
6. Gate firing circuit for SCR’s.
7. Single phase fully controlled bridge converter with R load and RL loads.
8. Forced commutation circuits (Class A, Class B, Class C, Class D & Class E).
9. Single phase cycloconverter with R and RL loads
10. PSPICE simulation of single phase inverter with PWM control.
.
4
TABLE OF CONTENTS
Sl.No
Experiment Name
Experiment Submission
Date
date
Marks
Signature
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
SUBJECT INCHARGE
INTERNAL MARK---------
5
Exp. No.:1
Date:
SINGLE PHASE AC VOLTAGE CONTROLLER WITH R AND RL LOADS
1.1 OBJECTIVE:
To study the module and waveforms of a 1-Φ AC voltage controller with R and RL loads.
1.2 RESOURCES:
S. No.
1
Name of the Apparatus
1 AC voltage regulator
power module
Range
Type
Quantity
-
-
1
2
Loading Rheostat
50, 2A
-
1
3
Loading Inductor
150mH, 2A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
1.3 SPECIFICATIONS:
1. Input
1, 230V, 50Hz AC Supply
2. Load
R and RL.
3. Thyristors
12A, 600V, type 25 RIA 120.
4. TRIACs
10A, 600V, BT136.
5. MCB
Two pole 230V/16A.
6. Fuses
16A HRC.
7. Step down transformer
230V/24V-0-24V, 2A.
1.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. Make sure to connect firing pulses from the firing circuit to their corresponding SCRs/TRIAC
in the power circuit.
6
1.5 MODEL GRAPH:
Vi (v)
0
Input Waveform
π
2π
3π
4π
t (ms)
Output Waveform Across R and RL- Load =00
VL (v)
t (ms)
0
Output Waveform Across R- Load
=900
VL (v)
0
t (ms)
Output Waveform Across RL- Load
=900
VL (v)
0
t (ms)
7
1.6 PROCEDURE:
1. Switch ON the mains supply to the firing circuit. Observe the trigger outputs by varying firing
angle potentiometer and by operating On/OFF and SCR/TRIAC selector switch. Make sure the
firing pulses are proper before connecting to the power circuit.
2. Make the connections as per the circuit diagram.
3. Connect firing pulses from the firing circuit to the corresponding SCRs/TRIAC in the power
circuit.
4. Switch ON the step down transformer supply (MCB) and now switch ON the trigger pulses by
operating ON/OFF switch in the firing circuit.
5. Observe the output voltage waveform across load using oscilloscope.
6. Note down the input voltage, firing angle and output voltage readings in the TABULAR
FORMS.
7. Draw the waveforms in the graph at 0, 45, 90, 135 and 180 Deg. firing angles.
FORMULAE USED:
Output voltage, V0 = Vs
1 
sin 2  
       2  

 
8
SINGLE PHASE AC VOLTAGE CONTROLLER WITH RL LOAD USING SCRS
T1
A1
K1
G1
2TYN616
P
G2
230V
K2
24V
1, 230V,
50Hz, AC
T2
R
K1 G1
K2 G2
0V
0V
A2
LOAD
50,2A
L
24V
N
SINGLE PHASE AC VOLTAGE CONTROLLER WITH RL LOAD USING
TRIAC
TRIAC
BT136 G
MT
P
1
230V
24V
1, 230V,
50Hz, AC
0V
G MT2
FIRING
CIRCUIT
MT
2
R
LOAD
50,2A
0-250mH, 2A
L
0V
24V
N
9
SINGLE PHASE AC VOLTAGE CONTROLLER WITH R LOAD USING SCRS
T1
A1
K1
G1
2TYN616
P
G2
230V
K2
24V
1, 230V,
50Hz, AC
T2
K1 G1
K2 G2
0V
0V
A2
R
LOAD
50,2A
24V
N
1.7 TABULAR FORMS: 1. for R load
S.No.
Input voltage (V)
Firing angle Output voltage
()
(V)
Theoretical
output
voltage (V)
1.7 TABULAR FORMS: 2. RL load:
S.No.
Input voltage (V)
Firing angle Output voltage
()
(V)
Theoretical
output
voltage (V)
10
1.8 MODEL CALCULATIONS:
1.9 RESULT:
Thus the single phase AC voltage controller with R & RL loads is studied and we plotted the
waveforms of different firing angle.
1.10 PRE LAB QUESTIONS:1. Why should the two trigger sources be isolated?
2. What are the advantages and the disadvantages of phase control?
3. What is phase control?
4. What are the advantages of bidirectional controllers?
5. What is meant by duty cycle in ON-OFF control method?
1.11 POST LAB QUESTIONS:1. What type of commutation is used in this circuit?
2. What are the effects of load inductance on the performance of AC voltage controllers?
3. What is extinction angle?
4. What are the disadvantages of unidirectional controllers?
5. What are the advantages of ON-OFF control?
11
Exp. No.:2
Date:
DC JONES CHOPPER WITH R AND RL LOADS
2.1 OBJECTIVE:
To study the module and waveforms of a DC Jones chopper with R and RL loads.
2.2 RESOURCES:
S. No.
Name of the
Apparatus
Range
Type
Quantity
-
-
1
Jones chopper firing
1
circuit module and
power circuit module
2
Loading Rheostat
50, 2A
-
1
3
Loading Inductor
150mH, 2A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
2.3 SPECIFICATIONS:
1. Input: 0 – 230V 1Φ AC supply.
2. Load
R, & RL
3. Thyristors
25A, 1200V, type 25 RIA 120.
4. Diodes:
25A, 1200V.
5. Commutating Capacitor
25µF, 440V
6. MCB
Two pole 230V/16A.
7. Fuses
16A HRC
2.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. Make sure to connect firing pulses from the firing circuit to their respective SCRs in the power
circuit.
12
2.5 MODEL GRAPH:
Voltage and Current waveforms in the Jones Chopper
Ig1
t
Ig2
ISCR2
t
t
VSCR2
t
Vc
t
Ic
ISCR1
t
t
`
t
VSCR1
VL
t
13
2.6 PROCEDURE:
1. Switch On the mains supply to the firing circuit. Observe the trigger on by varying duty cycle
and frequency potentiometer by keeping the c switch in ‘INT’ position. Make sure the firing
pulses are proper be connecting to the power circuit.
2. Make the connections as per the circuit diagram.
3. Connect firing pulses from the firing circuit to the respective SCRs power circuit.
4. Initially set the input DC supply to 5V.
5. At the beginning, keep the ON/OFF switch in the firing circuit in OFF position.
6. Switch ON the DC supply and now ON the trigger pulses by open On/OFF switch in the firing
circuit.
7. Observe the DC chopped voltage waveform across load using oscilloscope.
8. If the commutation fails, pure DC voltage can be observed across the then switch OFF the DC
supply and trigger pulses. Check the connect and try again.
9. Observe the voltage waveform across load, capacitor, main SCR auxiliary SCR by varying the
duty-cycle potentiometer and frequency potentiometer, using oscilloscope.
10. Now, vary the DC supply up to the rated voltage, 30VDC.
11. Note down the readings in the TABULAR FORMS.
12. Draw the waveforms in the graph at different duty cycles and at different
Formula used:
Theoretical value  = Ton/T100
T= Ton +Toff
14
2.7CIRCUIT DIAGRAM:
2.7.1 Circuit Diagram of DC Jones Chopper with RL Load
2.7.2Circuit Diagram of DC Jones Chopper with R Load
T1
+
TA
–
R
DC
Supply
V
D1
L1
To CRO
L2
15
2.8 TABULAR FORMS:
2.8.1 At F1 (middle)
S.
Input
No.
voltage
(Vin)
Time in milli sec.
Ton(ms)
Toff(ms)
Duty
Output
Theoretical
cycle
voltage
value  =
(%)
(V0)
Ton/T100
Duty
Output
Theoretical
cycle
voltage
value  =
(%)
(V0)
Ton/T100
2.8.2 At F2 (maximum)
S.
Input
No.
voltage
(Vin)
Time in milli sec.
Ton(ms)
Toff(ms)
2.9 RESULT:
Thus the module and waveforms of a DC Jones chopper with R and RL loads was studied.
2.10 PRE LAB QUESTIONS:1. What is a chopper? Where it is normally employed?
2. Explain the principle of operation of a chopper.
3. What are the control strategies used for a chopper?
4. What is time ratio control (TRC) of a chopper? How is it classified?
2.11 POSTLAB QUESTIONS:1. Why is forced commutation required in dc choppers?
2. What are the effects of turn on and turn off times of thyristor on the performance of the chopper.
3. What are the merits and demerits of this circuit?
4. What is current limit control of a chopper?
16
Exp. No.: 3
Date:
SINGLE PHASE PARALLEL INVERTER WITH R AND RL LOADS
3.1 OBJECTIVE:
To study the module and waveforms of a 1-Φ Parallel inverter with R and RL loads.
3.2 RESOURCES:
S. No.
Name of the
Apparatus
Range
Type
Quantity
-
-
1
1-Φ parallel inverter
1
firing module and
power circuit module
2
Loading Rheostat
50, 2A
-
1
3
Loading Inductor
150mH, 2A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
3.3 SPECIFICATION:
1. Input
230V, 50Hz, 1-Φ AC supply.
2. Load
R and RL.
3. Thyristors
10A, 600V.
4. Diodes
10A, 600V.
5. Capacitors
6.8µF, 100V.
7. Inductor
300mH, 2A.
9. Fuses
2A Glass fuse.
3.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. Make sure to connect firing pulses form the firing circuit to their respective SCRs in the power
circuit.
6. Ensure to switch OFF the input supply first and then trigger pulses to short circuit.
17
3.5 MODEL GRAPH:
TRIGGER OUTPUTS
T1
T2
+VDC
--VDC
3.6 PROCEDURE:
1. Switch ON the mains supply to the firing circuit. Observe the trigger output in the firing circuit
by varying frequency potentiometer and by operating OFF switch. Make sure the firing pulses
are proper before connecting to the power circuit.
2. Make the connections as per the circuit diagram.
3. Connect firing pulses form the firing circuit to the respective SCRs in power circuit.
4. Connect the DC input from a 30V, 2A regulated power supply.
5. Switch ON the DC supply, set input voltage to 15V and switch ON the trigger pulses by
operating ON/OFF switch in the firing circuit.
6. Observe the voltage waveform across load using oscilloscope.
7. Vary the frequency and observe the voltage waveforms across load with without freewheeling
diode.
8. Draw the waveforms in the graph at different frequencies.
9. To switch off the inverter, switch OFF the input supply first and then trigger pulses.
10. Since the parallel inverter works on forced commutation, there is a chopper commutation
failure. If the commutation fails, switch off the DC supply and then trigger outputs. Check the
connections and try again.
18
3.7 CIRCUIT DIAGRAM
3.7.1 Single Phase Parallel Inverter with R load
D1
T1
L
R
L
o
0V
C
T2
RPS
+
(0-30)V
DC
Supply
50,
2A
D2
L
3.7.2 Single Phase Parallel Inverter with RL load
D1
T
L
C
RPS
+
(0-30)V
DC
Supply
T
0V
RL
L
o
a
d
50,
150mH
2A
D2
19
3.8 TABULAR FORMS:
3.8.1For R Load:
S.
Input
Time in milli sec.
No. voltage
(Vin)
Ton(ms) Toff(ms)
Amplitude Output
Theoretical
in (V)
average output
Vm
voltage
frequency
(V0)
in Hz
3.8.2 For R-L Load:
S.
Input
No.
voltage
(Vin)
Time in milli sec.
Amplitude
Output
Theoretical
in (V)
average
output
voltage
frequency
(V0)
in Hz
Ton(ms) Toff(ms)
V1
V2
3.9 RESULT:
Thus the module and waveforms of a 1-Φ Parallel inverter with R and RL loads was studied.
3.10PRE LAB QUESTIONS:1. What is parallel inverter? Why is it called so?
2. What is the purpose of capacitor in the parallel inverter?
3. What is the purpose of transformer in the parallel inverter?
4. IS the parallel inverter naturally commutated or force commutated?
5. What are the advantages of parallel resonant inverters?
3.11 POST LAB QUESTIONS:1. What is the purpose of the inductor in the parallel inverter?
2. During its operation, capacitor voltage reaches 2Vs. How?
3. What is the significance of the split phase transformer?
4. During operation, what is the voltage across primary winding of the transformer?
5. Capacitor current flows in how many modes of the operation of parallel inverter?
20
Exp. No.:4
Date:
SINGLE PHASE HALF CONTROLLED CONVERTER WITH R LOAD
4.1 OBJECTIVE:
To study the module and waveforms of a 1-Φ Half controlled converter with R load at different firing
angles.
4.2 RESOURCES:
S. No.
Name of the Apparatus
Range
Type
Quantity
-
-
1
1 Half controlled
1
converter power and
firing module
2
Loading Rheostat
150, 5A
-
1
3
Loading Inductor
150mH, 5A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
4.3 SPECIFICATIONS:
1. Input
: 1, 230V , 50Hz AC supply.
2. Load
: R, RL
3. Thyristors
: 25A, 1200V, type 25 RIA 120/TYN616.
4. Diode
: 25A, 1200V, BY126/BY127.
5. MCB
: Two pole 230V/16A
6. Fuses
: 16A HRC.
7. Field Supply bridge rectifier
: 10A, 600V.
8. Field Supply
: 220V + 10%.
4.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
21
4.5 MODEL GRAPH:
Input Waveform
Vi (v)
t (ms)
0
π
2π
3π
Output Waveform R and RL - Load at
4π
=00
VL (v)
t (ms)
0
VL (v)
Output Waveform R and RL -Load at
=450
t (ms)
0
VL (v)
Output Waveform R and RL - Load at
=900
0
t (ms)
Output Waveform R and RL - Load at
=1350
t (ms)
0
22
4.6 PROCEDURE:
1. Switch ON the main supply to the firing circuit. Observe the trigger output by varying firing
angle potentiometer and by operating ON/OFF switch and their phase sequence. Make sure the
firing pulses are proper before connecting to the power circuit.
2. Make the connections as per the circuit diagram.
3. Connect 30V tapping of the transformer secondary to the power circuit.
4. Connect firing pulses 0from the firing circuit to their respective SCRs in power circuit.
5. Switch ON the MCB and now switch ON the trigger pulses by operate ON/OFF switch in the
firing circuit.
6. Observe the output voltage waveforms across load and devices us oscilloscope.
7. Note down the input voltage, firing angle, Output voltage and output circuit reading in the
TABULAR FORMS.
8. Repeat the same for different input voltage up to max. voltage as provided in the isolation
transformer.
9. Repeat the same for R-L and RLE loads with and without freewheeling diode.
10. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350 and 1800.
FORMULAE USED:
Output voltage V0 = Vdc = Vm/ (1 + cos )
23
4.7 CIRCUIT DIAGRAM:
4.7.1SINGLE PHASE HALF CONTROLLED CONVERTER WITH R LOAD
2TYN616
K1
P
230V
30V
0V
K2
G2
T1
A1
1, 230V,
50Hz, AC
0V
G1
A2
R
LOAD
150, 5A
K2
K1
D1
D2
A1
N
T2
A2
21N4007
4.7.2 SINGLE PHASE HALF CONTROLLED CONVERTER WITH RL
LOAD
2TYN616
K1
P
230V
30V
K2
T2
A1
0V
0V
G2
T1
1, 230V,
50Hz, AC
N
G1
A2
D1
LOAD
150, 5A
0-150mH, 5A
L
K2
K1
R
D2
A1
A2
21N4007
24
S. No.
Input
Firing
Output voltage
Output
voltage
angle (a)
(V)
Theoretical
voltage
(V)
4.8 TABULAR FORMS: for R load
S. No.
Input
Firing
Output voltage
Output
voltage
angle (a)
(V)
Theoretical
(V)
voltage
4.9 MODEL CALCULATIONS:
4.10 RESULT:
Thus the single phase half controlled converter with R and RL load is studied and also we
plotted the waveforms of different firing angles.
4.11 PRE LAB QUESTIONS:1. What is the delay angle control of converters?
2. What is natural or line commutation?
3. What is the principle of phase control?
4. What is extinction angle?
5. Can a freewheeling diode be used in this circuit and justify the reason?
4.12 POSTLAB QUESTIONS:1. What is conduction angle?
2. What are the effects of adding freewheeling diode in this circuit?
3. What are the effects of removing the freewheeling diode in single phase semi converter?
4. Why is the power factor of semi converters better than that of full converters?
5. What is the inversion mode of converters?
25
Exp. No.: 5
Date:
PSPICE SIMULATION OF SINGLE PHASE FULL CONVERTER AND SINGLE PHASE AC
VOLTAGE CONTROLLER USING RLE LOADS
5.1OBJECTIVE:
To study the output waveforms of single-phase full converter using RLE loads and single-phase AC
voltage controller using RLE loads using PSPICE simulation.
5.2 RESOURCES: PSPICE Software
AC Model of SCR:
F1= P1Ig + P2Ia
= 50Ig + 11Ia
26
5.3 Circuit diagram of single phase full converter:
5.4Circuit file for Single phase full converter:
VS 10 0 SIN (0 169.7V 60HZ)
VG1 6 2 PULSE (0V 10V 2777.8US 1NS 1NS 100US 16666.7US)
VG2 7 0 PULSE (0V 10V 2777.8US 1NS 1NS 100US 16666.7US)
VG3 8 2 PULSE (0V 10V 11111.1US 1NS 1NS 100US 16666.7US)
VG4 9 1 PULSE (0V 10V 11111.1US 1NS 1NS 100US 16666.7US)
R 2 4 10
L 4 5 20MH
C 2 11 793UF
RX 11 3 0.1
VX 5 3 DC 10V
VY 10 1 DC 0V
* SUBCIRCUIT CALLS FOR THYRISTOR MODEL
XT1 1 6 2 SCR
XT2 0 8 2 SCR
XT3 3 7 0 SCR
XT4 3 9 1 SCR
. SUBCKT SCR 1 3 2
S1 1 5 6 2 SMOD
RG 3 4 50
VX 4 2 DC 0V
27
VY 5 2 DC 0V
RT 2 6 1
CT 6 2 10UF
F1 2 6 POLY (2) VX VY 0 50 11
.MODEL SMOD VSWITCH (RON=0.01 ROFF=10E+5 VON=0.1V VOFF=0V)
.ENDS SCR
.TRAN 10US 35MS 16.67MS
.PROBE
.OPTIONS ABSTOL=1.00U RELTOL=1.0M VNTOL=0.1 ITL5=10000
.FOUR 120HZ I (VX)
.END
28
5.5 Circuit diagram of single phase Ac Voltage Controller:
5.6 Circuit file for Single phase ac voltage controller:
VS 10 0 SIN (0 169.7V 60HZ)
VG1 2 4 PULSE (0V 10V 4166.7US 1NS 1NS 100US 16666.7US)
VG2 3 1 PULSE (0V 10V 12500.0US 1NS 1NS 100US 16666.7US)
R 4 5 2.5
L 5 6 6.5MH
VX 6 0 DC 0V
CS 1 7 0.1UF
RS 7 4 750
* SUBCIRCUIT CALLS FOR THYRISTOR MODEL
XT1 1 2 4 SCR
XT2 4 3 1 SCR
. SUBCKT SCR 1 3 2
S1 1 5 6 2 SMOD
RG 3 4 50
VX 4 2 DC 0V
VY 5 2 DC 0V
29
RT 2 6 1
CT 6 2 10UF
F1 2 6 POLY (2) VX VY 0 50 11
.MODEL SMOD VSWITCH (RON=0.01 ROFF=10E+5 VON=0.1V VOFF=0V)
.ENDS SCR
.TRAN 10US 33.33MS
.PROBE
.OPTIONS ABSTOL= 1.00N RELTOL = 1.0M VNTOL=1.0M ITL5=10000
.FOUR 60HZ V (4)
.END
5.7RESULT :
The output waveforms of single-phase full converter using RLE loads and single-phase AC voltage
controller using RLE loads using PSPICE simulation are studied.
5.8 PRE LAB QUESTIONS:1. What is the difference between a diode rectifier and a thyristor rectifier?
2. What is controlled rectification?
3. What is meant by firing angle of a converter?
4. What is an ac voltage controller?
5. How does the load inductance effect the conduction angle of a controller?
5.9 POST LAB QUESTIONS:1. What is an integral cycle control?
2. What is phase control?
3. What is discontinuous in thyristor power converters?
4. How is it achieved in thyristor power converters?
5. What are the effects of load inductance on the performance of a power converter?
30
Exp. No.:6
Date:
GATE FIRING CIRCUITS FOR SCRs
6.1 OBJECTIVE:
To study the following various firing schemes for triggering SCRs when they are different converter
topologies employing line commutation.
1. Resistance firing circuit.
2. Resistance capacitance (RC) firing circuit.
3. UJT firing scheme.
6.2 RESOURCES:
S. No.
Name of the
Apparatus
Range
Type
Quantity
1
R & RC power module
-
-
1
2
UJT power module
-
-
1
3
R load
50, 2A
-
1
4
CRO & probe
Dual
-
1
5
Connecting wires
-
As required
6.3 SPECIFICATIONS:
1. SCRs
: 400V, 4A, type 106 D
2. Diodes
: 1N4007
3. Diacs
: D3202U
4. Zeners
: 20V, 1W
5. UJTs
: 2N2646
6. Pulse transformer : 1:1:1
6.4 PRECAUTIONS:
1. Make sure all the connections are tight.
2. Ensure all the controlling knobs are kept in fully counterclockwise position before starting
experiment.
3. Handle everything with care.
31
6.5 MODEL GRAPH:
Vi (v)
0
Input Waveform
π
2π
3π
4π
t (ms)
Output Waveform =0 0
VL (v)
t (ms)
0
VSCR (v)
0
t (ms)
Output Waveform =90 0
VL (v)
0
t (ms)
VSCR (v)
0
t (ms)
32
6.6 PROCEDURE:
(a). R firing circuit:
1. Make the connections as per the circuit diagram.
2. Connect a load rheostat of 50Ω, 2 A between the load points
3. Switch ON the power supply
4. Vary the control pot and observe the voltage waveforms across load and at different points in
the circuit using oscilloscope.
5. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350.
6. Bring the pot to the original position.
7. Switch OFF the power Supply.
(b). RC firing circuit:
1. Make the connections as per the circuit diagram.
2. Connect a load rheostat of 50Ω, 2 A between the load points
3. Switch ON the power supply
4. Vary the control pot and observe the voltage waveforms across load and at different points
in the circuit using oscilloscope.
5. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350 and 1800.
6. Bring the pot to the original position.
7. Switch OFF the power Supply.
(c). UJT firing circuit:
1. Make the connections as per the circuit diagram.
2. Connect a load rheostat of 50Ω, 2 A between the load points
3. Switch ON the power supply
4. Vary the control pot and observe the voltage waveforms across load and at different points
in the circuit using oscilloscope.
5. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350 and 1800.
6. Bring the pot to the original position.
7. Switch OFF the power Supply.
FORMULAE USED:
180 0
* t (deg rees )
3
Firing Angle  = 10 * 10
33
6.7 CIRCUIT DIAGRAM
GATE FIRING CIRCUIT FOR SCR’S-RESISTANCE
FIRING CIRUCIT
R LOAD
50, 2A
20V, 2A
AC
R
T1
TYN616
RC
A
K1
D
Rg
K
1N4007
6.8 TABULAR FORMS:
A. i. Resistance Firing Circuit: -
Sl.
Resistance (R) in
Firing angle
No.
Ω
() in s
1.
2.
3.
4.
5.
ii. Resistance Firing Circuit: - across SCR and Load
Firing
Sl.
(R) in
angle
No.
Ω
() in
Ton
Toff
Amplitude
s
1.
2.
3.
4.
5.
34
GATE FIRING CIRCUIT FOR SCR’S-RESISTANCE CAPACITANCE (RC)
FIRING CIRUCIT
R LOAD
50, 2A
20V, 2A
AC
A1
R
RC
T1
TYN616
D1
A
C
4.7F
D2
K
Rg
G1
K1
1N4007
B. i. Resistance Capacitance Firing Circuit: Sl.
Resistance (R)
Capacitance (c) Firing angle ()
No.
in Ω
in Fd
in s
1.
2.
3.
4.
5.
ii. Resistance Capacitance Firing Circuit: Firing
Sl.
(R) in
angle
No.
Ω
() in
Ton
Toff
Amplitude
s
1.
2.
3.
4.
5.
35
C. i. UJT Firing Circuit: -
GATE FIRING CIRCUIT FOR SCR’S-UJT FIRING CIRUCIT
R
P
50
, 2A
R
D3
D1
A
RC
1, 230V,
50Hz AC
K
20V
, 2A
C
1000F
D4
ZD
UJT
2N2646
A
4.7F
N
K
AC
20V, 2A
C
D2
T1
G
Pulse TFR
1:1:1
S.
Resistance (R) in
Firing angle
No.
Ω
() in s
1.
2.
3.
4.
5.
ii. UJT Firing Circuit: -
Firing
Sl.
(R) in
angle
No.
Ω
() in
Ton
Toff
R
L
O
A
D
Amplitude
s
1.
2.
3.
4.
5.
36
6.9 RESULT:
Thus the different types of gate firing circuits of SCR’s i. R Firing circuit, ii. RC Firing circuit and iii.
UJT firing circuit is studied and also plotted its waveforms.
6.10 PRE LAB QUESTIONS:1. UJT triggering circuit is also known as?
2. Types of triggering circuit?
3. What is the purpose of series resistor?
4. What is the condition for triggering the circuit?
5. What is the function of pulse transformer in firing circuit?
6.11 POST LAB QUESTIONS:1. Explain how synchronization of the triggering circuit with the supply voltage across SCR is
achieved?
2. How can the capacitor charging be controlled?
3. What is the maximum value of firing angle which can be obtained from the circuit?
4. How is the output power to the triggering circuit controlled?
5. Compare UJT triggering circuit with RC firing circuit?
37
Exp. No.:7
Date:
SINGLE PHASE FULLY CONTROLLED BRIDGE CONVERTER WITH R AND RL LOADS
7.1 OBJECTIVE:
To study the module and waveforms of a 1-Φ Full Bridge Converter with RL and RL loads.
7.2 RESOURCES:
S. No.
Name of the Apparatus
Range
Type
Quantity
-
-
1
1 Full bridge
1
controlled converter
power and firing
module
2
Loading Rheostat
150, 5A
-
1
3
Loading Inductor
150mH, 5A
-
1
5
CRO & probe
20MHz
Dual
1
6
Connecting wires
-
As required
7.3 SPECIFICATIONS:
1. Input
: 1, 230V 50Hz, AC supply.
2. Load
: R and RL loads.
3. Thyristors
: 16A, 1200V, type 16 TTS/TYN616
4. Diode
: 25A, 1200V, BY126/BY127
5. MCB
: Two pole 230V/16A
6. Fuses
: 16A HRC.
7. Field Supply bridge rectifier: 10A, 600V.
8. Field Supply
: 220V + 10%.
7.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
38
7.5 MODEL GRAPH:
Vi (v)
Input Waveform
t (ms)
0
π
2π
Output Waveform R- Load at
3π
4π
=00
VL (v)
t (ms)
0
VL (v)
0
VL (v)
Output Waveform R- Load at
t (ms)
RL- Load at
=450
t (ms)
0
VL (v)
R- Load at
=900
0
VL (v)
=450
t (ms)
RL- Load at
=900
t (ms)
0
VL (v)
R- Load at
=1350
t (ms)
0
39
7.6 PROCEDURE:
1. Switch ON the main supply to the firing circuit. Observe the trigger output by varying firing
angle potentiometer and by operating ON/OFF switch their phase sequence. Make sure the
firing pulses are proper before connecting to the power circuit.
2. Make the connections as per the circuit diagram.
3. Connect 30V tapping of the transformer secondary to the power circuit.
4. Connect firing pulses from the firing circuit to their respective SCRs in power circuit.
5. Switch ON the MCB and now switch ON the trigger pulses by operate ON/OFF switch in the
firing circuit.
6. Observe the output voltage waveforms across load and devices us oscilloscope.
7. Note down the input voltage, firing angle, Output voltage and output circuit reading in the
TABULAR FORMS.
8. Repeat the same for different input voltage up to max. voltage as provided in the isolation
transformer.
9. Repeat the same for R-L and RLE loads with and without freewheeling diode.
10. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350 and 1800.
FORMULAE USED:
Vm
1  cos  
Average output voltage – R load, VAvg= 
2Vm
cos  
Average output voltage – RL load, VAvg= 
40
7.7CIRCUIT DIAGRAM :
SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH R
LOAD
4TYN616
K1
P
230V
30V
G1
K3
G3
T1
T3
A1
1, 230V,
50Hz, AC
A3
R
0V
G4
K4
0V
T4
N
LOAD
150, 5A
G2
K2
T2
A2
A4
7.8TABULAR FORMS:
a. For R load
S.No.
Input voltage (V)
Firing
Output voltage
angle ()
(V)
Theoretical
Output
voltage (V)
41
SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH
RL LOAD
4TYN616
K1
P
230V
30V
G1
K3
T1
T3
A1
1, 230V,
50Hz, AC
0V
0V
G3
G4
K4
LOAD
150, 5A
0-150mH, 5A
L
G2
K2
T4
N
R
A3
T2
A2
A4
b. For RL load without freewheeling diode:
S.No.
Input voltage (V)
Firing
Output voltage
angle ()
(V)
Theoretical
Output
voltage (V)
42
SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH FREEWHEELING
DIODE FED RL LOAD
4TYN616
K1
P
230V
30V
K3
G1
G3
T1
T3
A1
1, 230V,
50Hz, AC
A3
R
K
FD
0V
0V
G4
K4
K2
T4
N
G2
A
L
LOAD
150, 5A
0-150mH, 5A
T2
A2
A4
c. For RL load with freewheeling diode:
S.No.
Input voltage (V)
Firing
Output voltage
angle ()
(V)
Theoretical
Output
voltage (V)
7.9 MODEL CALCULATIONS:
43
7.10 RESULT:
Thus the single phase Full controlled bridge converter with R and RL load is studied and also
plotted the waveforms of different firing angles.
7.11 PRE LAB QUESTIONS:1. State the type of commutation used in this circuit?
2. What will happen if the firing angle is greater than 90 degrees?
3. What are the performance parameters of rectifier?
4. What are the advantages of three phase rectifier over a single phase rectifier?
5. What is the difference between half wave and full wave rectifier?
7.12POST LAB QUESTIONS:1. If firing angle is greater than 90 degrees, the inverter circuit formed is called as?
2. What is Dc output voltage of single phase full wave controller?
3. What are the effects of source inductance on the output voltage of a rectifier?
4. What is commutation angle of a rectifier?
5. What are the advantages of three phase rectifier over a single phase rectifier?
44
Exp. No.:8
Date:
STUDY OF FORCED COMMUTATION CIRCUITS
8.1 OBJECTIVE: To Verify the different types of forced commutation circuits by connecting a
resistive load.
8.2 RESOURCES:
S.No
EQUIPMENT
Qty
1.
Forced commutation Kit
1
2.
Regulated Power Supply
1
3.
Rheostat
2
4.
CRO
1
5.
Patch cards
8.3 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
45
8.4 MODEL GRAPHS:
CLASS-A COMMUTATION:
CLASS-B COMMUTATION:
CLASS-C COMMUTATION:
CLASS-D COMMUTATION:
46
8.5 CIRCUIT DIAGRAM:
CLASS-A COMMUTATION:
CLASS-B COMMUTATION:
T1
L
L
T
C
(0-15V)
C
R
To CRO
(0-15V)
R
CLASS-C COMMUTATION:
To CRO
CLASS-D COMMUTATION:
T1
R1
R2
+
C
TA
–
(0-15V)
T1
T2
R
(0-30V)
D
L
47
8.6 PROCEDURE:
CLASS-A COMMUTATION:
1. Connect the circuit as shown in the circuit.
2. Connect Trigger output T1 to gate and cathode of SCR T1
3. Switch on the DC supply to the power circuit and observe the voltage waveform across load by
varying the frequency potentiometer.
4. Repeat the same for different values of L, C and R.
CLASS-B COMMUTATION:
1. Connect the circuit as shown in the circuit.
2. Connect Trigger output T1 to gate and cathode of SCR T1
3. Switch on the DC supply to the power circuit and observe the voltage waveform across load by
varying the frequency potentiometer.
4. Repeat the same for different values of L,C and R.
Note: Same procedure for Class-A and Class-B Commutation.
CLASS-C COMMUTATION:
1.
Connect the circuit as shown in the circuit.
2. Connect T1 and T2 from firing circuit to gate and cathode of Thyristor T1 and T2.
3. Observe the waveforms across R1,R2 and C by varying frequency and also duty cycle
potentiometer.
4. Repeat the same for different values of C and R.
CLASS-D COMMUTATION:
1. Connect the circuit as shown in the circuit.
2. Connect T1 and T2 gate pulse from the firing circuit to the corresponding SCR’s in the power
circuit.
3. Initially keep the trigger ON/OFF at OFF position to initially charge the capacitor, this can be
observed by connecting CRO across the capacitor.
4. Now switch ON the trigger output switch and observe the voltage waveform across the load
T1, T2 and capacitor. Note down the voltage waveforms at different frequency of chopping
and also at different duty cycle.
5. Repeat the experiment for different values of load Resistance, commutation inductance and
capacitance.
48
8.7 TABULAR FORMS:
S.No.
Classes
Time in milli sec.
Amplitude in Volts
Ton(ms)
VL
Toff(ms)
VSCR
+V
Vc
–V
A
A
S.No.
Classes
Time in milli sec.
Amplitude in Volts
Ton(ms)
VL
Toff(ms)
VSCR
+V
VC
–V
+V
–V
B
B
B
S.No.
Classes
Time in milli sec.
Amplitude in Volts
Ton(ms)
VL
Toff(ms)
V1
VSCR
V2
+V
VC
–V
+V
–V
C
C
C
S.No.
Classes
Time in milli sec.
Amplitude in Volts
Ton(ms)
VL
Toff(ms)
VSCR
+V
VC
–V
+V
–V
D
D
D
49
8.8 RESULT: The operations of class- A, B, C, and D are observed.
8.9 PRE LAB QUESTIONS:1. What is meant by commutation?
2. List out the commutation techniques?
3. Why is forced commutation required in dc choppers?
4. Explain the working principle of type E Chopper?
8.10 POST LAB QUESTIONS:1. What is a four quadrant chopper?
2. What is the commutation angle of a rectifier?
3. What are the effects of source inductances on the output voltage of a rectifier?
4. What is a commutation of diodes?
50
Exp. No.:9
Date:
SINGLE PHASE CYCLO CONVERTER WITH R & RL LOADS
9.1OBJECTIVE:
To verify the operation of single phase Cyclo Converter with R and RL Loads and to observe
the output and input waveforms
9.2 RESOURCES:
S.No
1.
2.
EQUIPMENT
I-φ Center tapped
Transformer
I-φ Cyclo Converter power
circuit with firing unit
Qty
1
1
3.
Rheostat
1
4.
Inductive load
1
5.
Voltmeter(MI)
1
6.
CRO with (1:10) Probe
1
7.
Patch cards
1 set
9.3 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
51
9.4 MODEL GRAPHS:
1/2f cycloconverter waveforms
1/3f cyclo converter waveforms
1/4f cycloconverter waveforms
52
9.5 CIRCUIT DIAGRAMS:
T1
Ph
T3
1-Φ, 230V 50Hz
AC Supply
R
To CRO
T2
N
center tapped
transformer
T4
Fig1-Single phase cyclo converter with R-load
T1
Ph
T3
R
1-Φ, 230V
50Hz
AC Supply
To CRO
T2
L
N
center tapped
transformer
T4
Fig2-Single phase cyclo converter with RL-loadFig-2
53
9.6 PROCEDURE:
A) For R-Load:
1. Connect the circuit as shown in figure.
2. Verify the connections from the lab instructor before switch on the supply.
3. Keep the rheostat position value given by the lab instructor
4. Switch ON the supply and note down the frequency of input voltage from the CRO.
5. Set the frequency division switch at 2 and note the readings of time period of output
voltage waveform for different set of firing angles
6. Calculate the practical value of output frequency by reciprocating the value of time
period and theoretical value of frequency will be found from frequency division setting
7. Repeat the above process from step 5 to 6 for frequency division of 3 and 4.
B). For RL-Load:
1. Connect the circuit as shown in figure.
2. Connect an inductance of given value in series with the load resistance.
3. Verify the connections from the lab instructor before switch on the supply.
4. Keep the rheostat position value given by the lab instructor
5. Switch ON the supply and note down the frequency of input voltage from the CRO.
6. Set the frequency division switch at 2 and note the readings of time period of output
voltage waveform for different set of firing angles
7. Calculate the practical value of output frequency by reciprocating the value of time
period and theoretical value of frequency will be found from frequency division
setting
8. Repeat the above process from step 5 to 6 for frequency division of 3 and 4.
54
9.7 TABULAR FORMS:
A) For R-Load:
The input voltage Vph =
V (As given by the instructor)
Value of load resistance RL=
Ω(As given by the instructor)
Input frequency
=
S.NO. Frequency
division
Hz
Firing angle(α)
Time period in
Frequency
Frequency
in degrees
msec
(practical)
(theoretical)
B) For RL-Load:
The input voltage Vph =
V (As given by the instructor)
Value of load resistance RL=
Ω(As given by the instructor)
Value of Load inductance L=
mH(As given by the instructor)
S.NO. Frequency
division
Firing angle(α)
Time period in
Frequency
Frequency
in degrees
msec
(practical)
(theoretical)
9.8 RESULT: The operation of I-φ cyclo converter is verified and the theoretical and practical values
of output frequencies at different frequency divisions are found both for R & RL loads
9.9PRE LAB QUESTIONS:1. On what principle does cycloconverter works?
2. What is the major difference between AC voltage controller and cycloconverter?
3. What type of commutation is employed in cycloconverter?
9.10 POST LAB QUESTIONS:1. What is the purpose of reactor connected in cycloconverter?
2. What happens to the output if the frequency of operation is beyond suggested limit?
3. What are the applications of cycloconverter?
55
Exp. No.:10
Date:
PSPICE SIMULATION OF SINGLE PHASE INVERTER WITH PWM CONTROL
10.1 OBJECTIVE: To study the output of single phase Inverter with PWM control using PSPICE
simulation.
10.2 Resources: PSPICE Software
10.3CIRCUIT DIAGRAMS OF SINGLE PHASE INVERTER WITH PWM CONTROL
(a) Circuit
(b) PWM generator
56
(c) carrier and reference signals
10.4 CIRCUIT MODEL FOR SINGLE PHASE INVERTER WITH PWM CONTROL
VS 1 0 DC 100V
VR 17 0 PULSE (50V 0V 0 833.33US 833.33US 1NS 16666.67US)
RR 17 0 2MEG
VC1 15 0 PULSE (0 -30V 0 1NS 1NS 8333.33US 16666.67US)
RC1 15 0 2MEG
VC3 16 0 PULSE (0 -30V 8333.33US 1NS 1NS 8333.33US 16666.67US)
RC3 16 0 2MEG
R 4 5 2.5
L 5 6 10MH
VX 3 4 DC 0V
VY 1 2 DC 0V
D1 3 2 DMOD
D2 0 6 DMOD
D3 6 2 DMOD
D4 0 3 DMOD
.MODEL DMOD D (IS=2.2E-15 BV=1800V TT=0)
Q1 2 7 3 QMOD
Q2 6 9 0 QMOD
Q3 2 11 6 QMOD
Q4 3 13 0 QMOD
.MODEL QMOD NPN(IS=6.734F BF=416.4 CJC=3.638P CJE=4.493P)
RG1 8 7 100
RG2 10 9 100
RG3 12 11 100
RG4 14 13 100
* SUBCIRCUIT CALL FOR PWM CONTROL
XPW1 17 15 8 3 PWM
57
XPW2 17 15 10 0 PWM
XP3 17 16 12 6 PWM
XP4 17 16 14 0 PWM
* SUBCIRCUIT FOR PWM CONTROL
.SUBCKT PWM 1 2 3 4
R1 1 5 1K
R2 2 5 1K
RIN 5 0 2MEG
RF 5 3 100K
RO 6 3 75
CO 3 4 10PF
E1 6 4 0 5 2E+5
.ENDS PWM
.TRAN 10US 16.67MS 0 10US
.PROBE
.OPTIONS ABSTOL 1.00N RELTOL=0.01 VNTOL=0.1 ITL5=20000
.FOUR 60HZ V (3, 6)
.END
10.5 RESULT:
PSPICE simulation of single phase Inverter with PWM control is studied and output
waveforms are observed.
10.6PRE LAB QUESTIONS:1. What are the disadvantages of PWM control?
2. What are the methods of reduction of harmonic content?
3. What is meant by PWM control?
4. What are the main classifications of inverter?
10.7POST LAB QUESTIONS:1. What is meant by inverter?
2. What is McMurray Inverter?
3. How is the inverter circuit classified based on commutation circuitry?
4. What are the applications of an inverter?
58
Exp. No.:11
Date:
PSPICE SIMULATION OF BUCK CHOPPER AND RESONANT PULSE COMMUTATION
11.1OBJECTIVE:
Study of resonant pulse commutation circuit and Buck chopper with PSPICE simulation
11.2 RESOURCES: PSPICE Software
11.3 CIRCUIT DIAGRAM OF RESONANT PULSE COMMUTATION
11.4 CIRCUIT FILE FOR RESONANT PULSE COMMUTATION
VS 1 0 DC 12V
VY 1 2 DC 0V
VG 8 0 PULSE(0V 20V 0 1NS 1NS 12.24US 40US)
RB 8 7 250
R 6 0 10
LE 2 3 25.47UH
CE 3 0 1.38UF
C 3 4 0.0958UF
L 5 6 445.63UH
VX 4 5 DC 0V
Q1 3 7 0 MODQ1
.MODEL MODQ1NPN (IS=6.734F BF=416.4 ISE=6.734F BR=.7371
+ CJE=3.637P MJC=0.3085 VJC=.75 CJE=4.493P MJE=.2593 VJE=.75
+ TR=239.5N TF=301.2P)
.TRAN 2US 300US 180US 1US UIC
.PROBE
.OPTIONS ABSTOL=1.00N VNTOL=0.1 ITL5=20000
.END
59
11.5 Circuit diagram of buck converter
11.6 CIRCUIT MODEL FOR BUCK CHOPPER
VS 1 0 DC 110V
VY 1 2 DC 0V
VG 7 3 PULSE (0V 20V 0 0.1NS 0.1 NS 27.28US 50US
RB 7 6 250
LE 3 4 681.82UHCE 4 0 8.33UF IC=60V
L 4 8 40.91UH
R853
VX 5 0 DC 0V
DM 0 3 DMOD
.MODEL DMOD D (IS=2.2E-15 BV=1800V TT=0)
Q1 2 6 3 QMOD
.MODEL QMOD NPN (IS=6.734F BF=416.4 BR=.7371 CJC=3.638P
+ CJE=4.493P TR=239.5N TF=301.2P)
.TRAN 1US 1.6MS 1US UIC
.PROBE
.OPTIONS ABSTOL=1.00N RELTOL=0.01 VNTOL=0.1 ITL5=50000
.FOUR 20KHZ I(VY)
.END
11.7 RESULT: PSPICE simulation of resonant pulse commutation circuit and Buck chopper is
studied and output waveforms are observed.
60
11.8 PRE LAB QUESTIONS:1. What is PSPICE?
2. What is the principle of Buck Chopper?
3. What are the different types of chopper with respect to commutation process?
11.9 POST LAB QUESTIONS:1. What are the applications of dc chopper?
2. What is commutation angle or overlap?
3. What are the advantages of current commutated chopper?
61
Exp. No.:12
Date:
STUDY OF CHARACTERISTICS OF SCR, MOSFET & IGBT
A. STUDY THE CHARACTERISTICS OF SCR.
12.1 OBJECTIVE:
To plot the forward characteristics of SCR and the find the forward Resistance.
12.2 RESOURCES:
S. No.
Name of the
Apparatus
Range
Type
Quantity
1
SCR
TYN 616
-
1
2
Ammeter
(0 – 100)mA
MC
1
3
Ammeter
(0 – 25)mA
MC
1
4
DMW
(0 – 5)V
MC
1
5
RPSU
(0 – 30)V
DC
2
6
Connecting wires
-
-
As required
12.3 PROCEDURE:
1. Make the connections as per the circuit diagram.
2. Keep E1 & E2 (RPSU) at minimum position.
3. Set load potentiometer in minimum position.
4. Switch ON the supply and to set some value of Vak voltage (5V to 7V).
5. BY adjusting E2 and set some value of IG (constant).
6. Slowly vary E1 and note down the corresponding Vak and meter readings.
7. By varying E2 (or) Gate current potentiometer R2, adjust IG to some other values (constant).
8. Repeat the same procedure step 6 to obtain the different values of Vak and Ia.
9. Bring back everything to minimum position then switch off the supply.
10. Draw the graph Vak Vs Ia.
11. Then from the forward characteristics take the slope and find out forward resistance by using
the formulae
Vak
()

I
a
Rf =
62
STUDY OF CHARACTERISTICS OF SCR
(0-100mA)mc
R1 = 1kΩ
+ Ia -
A
R2
V2
RPS
(0 –
30V)
(0-25mA)mc
+
Ig
+
TYN Vak (0-5V)mc
616
-
G
K
+ V1
RPS
- (0 –
30V)
+
-
12.4TABULAR FORMS:
IG1 =__________ (mA)
S.No.
VAK (volts)
IA (mA)
IG2 = ________ (mA)
S.No.
VAK (volts)
IA (mA)
63
12.5 MODEL GRAPH:
Ia
(ma)
IL
IA2
IA1
IG
IH
IG
IG1 >
IG2
VAK1 VAk2
O
VBO1 VBO2
VAK (Volts)
12.6 RESULT:
Thus the characteristics of SCR’s is studied and we plotted the forward characteristics of
SCR’s also found the forward resistance, RF=____ ()
64
B. TO STUDY THE CHARACTERISTICS OF MOSFET
12.7 OBJECTIVE:
To plot the transfer characteristics and drain characteristics of MOSFET.
12.8 RESOURCES:
S. No.
Name of the Apparatus Range
Type
Quantity
1
MOSFET
IRF 740
-
1
2
Ammeter
(0 – 500)MA
MC
1
3
Voltmeter
(0 – 20V)
MC
1
4
Voltmeter
(0 – 50V)
MC
1
5
RPS
(0 – 30)V
DC
2
6
Connecting wires
-
-
As required
12.9 PROCEDURE:
a. Transfer characteristics:1. Make the connections as per the circuit diagram.
2. Keep E1 &E2 (RPS) at minimum position initially.
3. Switch on the power supply.
4. Set E1 to some voltage (constant) and note down the readings of ID AND Vgs in steps by
adjusting E2 in step of 0.5 volt.
5. Bring back E1 & E2 to minimum position and switch off the power supply.
6. Plot the graph Vgs Vs ID.
FORMULAE USED:
Trans conductance (GM) = Change in Drain current / Change in Gate source voltage
= ΔID/ΔVGS
65
12.10TABULAR FORMS:
Trans conductance characteristics:
S.No.
ID (A)
VDS = _____ (V)
VGS (V)
b. Drain Characteristics:
12.11PROCEDURE:
1. Make the connections as per the circuit diagram.
2. Switch ON the supply.
3. Initially set some value of VGS by adjusting E2.
4. Slowly vary E1 and note down the readings of ID and ‘VDS’
5. Set some other values of VGS and repeat the procedure step 4.
6. Bring back E1 and E2 position in minimum and switch off the power supply.
7. Plot the graph ID Vs VDS
FORMULAE USED:
Drain Resistance (RD) = ΔVDS/ΔID
66
STUDY OF CHARACTERISTICS OF MOSFET
(0-500mA)mc
R1
+
Id
A
D
+
IRF
740
Vds (0-50V)mc
-
G
S
+ V1
RPS
(0 –
- 30V)
+
+
V2
RPS
(0-30V)
-
Vgs (0-20V)mc
-
12.12 TABULATION:
Drain characteristic:S.No.
VGS = _________(V)
ID (A)
VDS (V)
67
12.13 MODEL GRAPH:
TRANS CONDUCTANCE CHARACTERISTICS
ID
V DS = 15V
ID
(on)
V GS (Th)
3.5V
V GS (on)
V DS
DRAIN CHARACTERISTICS
ID in
mA
V GS = 3.6V
V GS = 3.55V
V GS = 3.5V
V DS
12.14RESULT:
Thus the characteristics of MOSFET is studied and we plotted the Trans conductance and drain
characteristics of MOSFET and also found the Trans conductance, Gm=____ ( ), Drain Resistance
Rd=______ ()
68
C. STUDY CHARACTERISTICS OF IGBT
12.15OBJECTIVE:
To obtain transfer and output characteristics of IGBT.
12.16 RESOURCES:
S. No.
Name of the
Apparatus
Range
Type
Quantity
1
IGBT
IRGBC 205
-
1
2
Ammeter
(0 – 500)MA
MC
1
3
Voltmeter
(0 – 20V)
MC
1
4
Voltmeter
(0 – 50V)
MC
1
5
RPS
(0 – 30)V
DC
2
6
Connecting wires
-
-
As required
12.17 PROCEDURE:
Transfer characteristics:
1. Make connection as per the circuit diagram.
2. Set E1& E2 (RPS) to minimum position Initially.
3. Switch ON the supply.
4. Set some value of VCE (constant) by adjusting E1.
5. Vary E2 in steps and note down the corresponding reading of VGE and IC.
6. Bring back E1 & E2 to original position and switch off the power supply.
7. Plot the graph VGE Vs IC.
O/P or Collector characteristics:
1. Make the connections as per the circuit diagram.
2. Set some value of VGE (constant) and by adjusting E2.
3. Slowly vary E1 and note down the readings of VCE and IC values.
4. For some other value of VGE (constant), repeat the procedure step 3.
5. Bring back E1 & E2 to minimum position and switch off the power supply.
6. Plot the graph VCE Vs IC.
69
STUDY OF CHARACTERISTICS OF IGBT
(0-500mA)mc
+ Ic -
IRBGC
20S
R1
C
+
G
Vce (0-50V)mc
E
V2
RPS
(0 –
30V)
+ V1
RPS
(0 –
30V)
+
+
Vge (0-20V)mc
-
-
12.18 TABULAR FORMS:a. Transfer characteristics:
VCE = _________ (V)
S.No.
VGE (V)
IC (mA)
70
b. O / P or collector characteristics:
VGE = _________ (V)
S.No.
VCE (V)
IC (mA)
12.19MODEL GRAPH:
TRANSFER CHARACTERISTICS
IC
V CE = 15V
IC
(on)
V CE (Th)
5V
V CE (on)
V CE
COLLECTOR CHARACTERISTICS
IC in
mA
V GE = 5.25V
V GE = 5.2V
V GE = 5.15V
V GE = 5.1V
V CE
12.20 RESULT:
Thus the characteristic of IGBT is studied and we plotted the Transfer and collector
characteristics of IGBT.
71
Exp. No.:13
Date:
SINGLE PHASE SERIES INVERTER WITH R AND RL LOADS
13.1 OBJECTIVE:
To study the operation of Single-phase series inverter with R and RL loads and plot its output
waveform.
13.2 RESOURCES:
S.No.
ITEM
RANGE
TYPE
QUANTITY
1
Series inverter power circuit kits
1 Ф ,230 V , 2 A
1
2
Series inverter firing circuit kit
1 Ф ,230 V , 2 A
1
3
Loading rheostat
100  / 2A
1
4
Loading Inductor
150mH, 5A
5
Regulated power supply
(0 – 30 V) / 2 A
1
6
CRO
20 MHZ
1
7
Patch chords
-
1
15
13.3 MODEL GRAPH (SERIES INVERTER):
T1
T2
t
ec1
t
ec2
t
t
eo
t
72
13.4 PROCEDURE (SERIES INVERTER) :
1. Make the connections as per the circuit diagram.
2. Switch on the thyristor firing circuit
3. Keep the frequency knob of the firing circuit kit below the resonance Frequency of power
circuit kit
4. Switch on the DC power supply connected to the power circuit kit and Switch on the firing
circuit kit
5. Vary the frequency knob of the firing circuit kit
6. Observe the waveform from the CRO.
7. Repeat the same procedure for different values of L,C and load resistance.
8. Switch of the power supply and disconnect the connection
9. Calculate the frequency of the output waveform.
13.5 CIRCUIT DIAGRAM -SERIES INVERTER
T1
FUSE2A
D1
C1
(0-30V), M.I
V
L1
LOAD
(0-30)V
RPS
L2
CRO
D2
T2
C2
73
13.6 TABULAR FORMS (SERIES INVERTER):
RESONANCE FREQUENCY = ____________: FIRING ANGLE = __________
S.No.
Input Voltage
Frequency Of Firing
Output Voltage
(Vi) Volts
Circuit (Hz)
Vo (Volts)
13.7 RESULT:
Thus a single-phase series inverter operation was studied and its output waveform was plotted.
13.8 PRE LAB QUESTIONS:1. What is series inverter?
2. What are the advantages of basic series inverter?
3. Compare basic &modified series inverter?
13.9 POST LAB QUESTIONS:1.
What is the condition for resonant circuit behave like a capacitive load and inductive load in
series resonant inverter
2.
What are the drawbacks of a basic series inverter?
3.
What are the applications of series inverters?
4.
Why are the inductors L1, L2 and why are two capacitors needed?
74
Exp. No.:14
Date:
THREE PHASE HALF CONTROLLED BRIDGE CONVERTER WITH R LOADS.
14.1 OBJECTIVE
The objective of Experiment is to analyze the operation (Switching) of three phase half
controlled rectifiers with resistive load.
14.2 RESOURCES:
S. No.
Name of the Apparatus
Range
Type
Quantity
-
-
1
3 Half controlled
1
converter power and
firing module
2
Loading Rheostat
150, 5A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
14.3 SPECIFICATIONS:
Input Supply
:
Output
Gate drive current
Gate Voltage
Gate pulse width
Firing angle control
:
:
:
:
:
Test points
:
415V / 3ph. Supply for phase synchronization and 230V, 50Hz
Single phase supply for the power supply
Six pairs of pulse transformer isolated trigger pulses.
230mA.
Open circuit- 5.1V, SCR LOAD-1.2V.
Fixed 6.3 msec.
Internal 180° to 0° phase control by Potentiometer
External 180° to 0° phase control obtained by external control
voltage between Vc and GND.
R, Y, B isolated signals for monitoring with respect to GND 1 to 8
– provide the test signals at various points of the trigger circuit.
14.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
75
14.5 Waveform:
14.6 Circuit diagram:
76
14.7 PROCEDURE :
1. Connect the three-phase half wave controlled rectifier circuit shown in Fig.(1) on the power
electronic trainer.
2. Turn on the power.
3. By use oscilloscope, plot the input and output waveforms on the same graph paper" same axis".
4. Measure the average and RMS output voltage by connect the AVO meter across load resistance.
5. Turn off the power
6. Use an inductive load. With L=10mH measure the output voltage and plot the output waveform.
7. Repeat step 6 with L=100mH measure the output voltage and plot the output waveforms.
8. Repeat step 6 & 7 with connect the freewheeling diode across the load
14.8 TABULAR FORMS: 1. for R load
S. No.
Input
Firing
Output voltage
Output
voltage
angle (a)
(V)
Theoretical
(V)
voltage
14.9 Result:
Thus the operation (Switching) of three phase half controlled rectifiers with resistive load was studied.
14.10PRE LAB QUESTIONS:1. What is the delay angle control of converters?
2. What is natural or line commutation?
3. What is extinction angle?
4. Can a freewheeling diode be used in this circuit and justify the reason?
14.11 POSTLAB QUESTIONS:1. What is conduction angle?
2. What are the effects of adding freewheeling diode in this circuit?
3. What are the effects of removing the freewheeling diode in three phase semi converter?
77
Exp. No.:15
Date:
SINGLE PHASE BRIDGE CONVERTER WITH R AND RL LOADS.
15.1OBJECTIVE:
To study the module and waveforms of a 1-Φ Bridge Converter with RL and RL loads.
15.2 RESOURCES:
S. No.
Name of the Apparatus
Range
Type
Quantity
-
-
1
1 Full bridge
1
controlled converter
power and firing
module
2
Loading Rheostat
150, 5A
-
1
3
Loading Inductor
150mH, 5A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
15.3 SPECIFICATIONS:
1. Input
: 1, 230V 50Hz, AC supply.
2. Load
: R and RL loads.
3. Thyristors
: 16A, 1200V, type 16 TTS/TYN616
4. Diode
: 25A, 1200V, BY126/BY127
5. MCB
: Two pole 230V/16A
6. Fuses
: 16A HRC.
7. Field Supply bridge rectifier: 10A, 600V.
8. Field Supply
: 220V + 10%.
15.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
78
15.5 MODEL GRAPH:
Vi (v)
Input Waveform
t (ms)
0
π
2π
Output Waveform R- Load at
3π
4π
=00
VL (v)
t (ms)
0
VL (v)
0
VL (v)
Output Waveform R- Load at
t (ms)
RL- Load at
=450
t (ms)
0
VL (v)
R- Load at
=900
0
VL (v)
=450
t (ms)
RL- Load at
=900
t (ms)
0
VL (v)
R- Load at
=1350
t (ms)
0
79
15.6PROCEDURE:
1. Switch ON the main supply to the firing circuit. Observe the trigger output by varying firing
angle potentiometer and by operating ON/OFF switch their phase sequence. Make sure the
firing pulses are proper before connecting to the power circuit.
2. Make the connections as per the circuit diagram.
3. Connect 30V tapping of the transformer secondary to the power circuit.
4. Connect firing pulses from the firing circuit to their respective SCRs in power circuit.
5. Switch ON the MCB and now switch ON the trigger pulses by operate ON/OFF switch in the
firing circuit.
6. Observe the output voltage waveforms across load and devices us oscilloscope.
7. Note down the input voltage, firing angle, Output voltage and output circuit reading in the
TABULAR FORMS.
8. Repeat the same for different input voltage up to max. voltage as provided in the isolation
transformer.
9. Repeat the same for R-L and RLE loads with and without freewheeling diode.
10. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350 and 1800.
FORMULAE USED:
Vm
1  cos  
Average output voltage – R load, VAvg= 
2Vm
cos  
Average output voltage – RL load, VAvg= 
80
SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH R
LOAD
4TYN616
K1
P
230V
30V
G1
K3
G3
T1
T3
A1
1, 230V,
50Hz, AC
A3
R
0V
G4
K4
0V
T4
N
LOAD
150, 5A
G2
K2
T2
A2
A4
15.7TABULAR FORMS:
a. For R load
S.No.
Input voltage (V)
Firing
Output voltage
angle ()
(V)
Theoretical
Output
voltage (V)
81
SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH
RL LOAD
4TYN616
K1
P
230V
30V
G1
K3
T1
T3
A1
1, 230V,
50Hz, AC
0V
0V
G3
G4
K4
L
G2
K2
T4
N
R
A3
LOAD
150, 5A
0-150mH, 5A
T2
A2
A4
b. For RL load without freewheeling diode:
S.No.
Input voltage (V)
Firing
Output voltage
angle ()
(V)
Theoretical
Output
voltage (V)
15.8 MODEL CALCULATIONS:
82
15.9RESULT:
Thus the single phase Full controlled bridge converter with R and RL load is studied and
also plotted the waveforms of different firing angles.
15.10PRE LAB QUESTIONS:1. State the type of commutation used in this circuit?
2. What will happen if the firing angle is greater than 90 degrees?
3. What are the performance parameters of rectifier?
4. What are the advantages of three phase rectifier over a single phase rectifier?
5. What is the difference between half wave and full wave rectifier?
15.11 POST LAB QUESTIONS:1. If firing angle is greater than 90 degrees, the inverter circuit formed is called as?
2. What is Dc output voltage of single phase full wave controller?
3. What are the effects of source inductance on the output voltage of a rectifier?
4. What is commutation angle of a rectifier?
5. What are the advantages of three phase rectifier over a single phase rectifier?
83
Exp. No.:16
Date:
OPERATION OF MOSFET BASED CHOPPER.
16.1OBJECTIVE:
To study the Step up & Step down MOSFET based choppers and draw its output response
graph.
16.2 RESOURCES:
ITEM
S.NO
1
Step up & Step down MOSFET
RANGE
QUANTITY
-
1
based chopper kit
2
CRO
3
Patch chords
20 MHZ
-
1
15
16.3 MODEL GRAPH (STEP UP CHOPPER) :
MODEL GRAPH (STEP DOWN CHOPPER) :
84
16.4PROCEDURE (STEP UP CHOPPER & STEP DOWN CHOPPER) :
1.
Initially keep all the switches in the OFF position
2.
Initially keep duty cycle POT in minimum position
3.
Connect banana connector 24V DC source to 24V DC imput.
4.
Connect the driver pulse [output to MOSFET input
5.
Switch on the main supply
6.
Check the test point waveforms with respect to ground.
7.
Vary the duty cyle POT and tabulate the Ton, Toff & output voltage
8.
Trace the waveforms of Vo Vs & Io
9.
Draw the graph for Vo Vs Duty cycle, K
16.5 CIRCUIT DIAGRAM (STEP UP CHOPPER) :
16.6 CIRCUIT DIAGRAM (STEP DOWN CHOPPER):
85
16.7 TABULAR FORMS (STEP UP CHOPPER):
Vs = ____________ V
S.NO
T
ON TOFF
(sec)
(sec)
T
Duty Ratio, k=TON / T
Vo=kVs(V)
(sec)
TABULAR FORMS (STEP DOWN CHOPPER):
Vs = ____________ V
S.NO
T
ON TOFF
(sec)
(sec)
T
Duty Ratio, k=TON / T
Vo=kVs(V)
(sec)
16.8RESULT:
Thus the output response of Step down & Step up MOSFET based choppers was drawn.
16.9PRE LAB QUESTIONS:1.
2.
3.
4.
What is control methods used in f chopper?
What is meant by step-up and step-down chopper?
Power MOSFET is a voltage controlled device. Why?
What are the different types of power MOSFET?
16.10POST LAB QUESTIONS:1. What is meant by step-up and step-down chopper?
2. What are the advantages of three phase rectifier over a single phase rectifier?
3. What are the advantages of MOSFET’s over BJT’s?
86
Exp. No.:17
Date:
SINGLE PHASE DUAL CONVERTER WITH RL LOAD
17.1OBJECTIVE:
To study and observer the operation of single phase dual converter with RL loads.
17.2RESOURCES:
S. No.
Name of the Apparatus
Range
Type
Quantity
-
-
1
1 dual converter
1
power and firing
module
2
Loading Rheostat
150, 5A
-
1
3
Loading Inductor
150mH, 5A
-
1
4
CRO & probe
20MHz
Dual
1
5
Connecting wires
-
As required
17.3SPECIFICATIONS:
1. Input
: 1, 230V 50Hz, AC supply.
2. Load
: R and RL loads.
3. Thyristors
: 16A, 1200V, type 16 TTS/TYN616
4. Diode
: 25A, 1200V, BY126/BY127
5. MCB
: Two pole 230V/16A
6. Fuses
: 16A HRC.
17.4 PRECAUTIONS:
1. Make sure all the connecting links are tightly fixed.
2. Ensure all the controlling knobs in fully counterclockwise position before starting experiment.
3. Handle everything with care.
4. Make sure the firing pulses are proper before connecting to the power circuit.
5. If the output is zero even after all power connections, switch OFF the MCB and just
interchange AC input connections to the power circuit. This is to make the firing circuit and
power circuit to synchronize.
87
17.5 MODEL GRAPH:
NON CIRCULATING CURRENT MODE:
P-TYPE CONVERTER AND N TYPE CONVERTER:
CIRCULATING CURRENT MODE:
N TYPE CONVERTER
P TYPE CONVERTER
17.6 PROCEDURE:
1. Switch ON the single phase dual converter firing circuit. Make sure all the pulses are proper
before connecting to the power circuit.
2. Make the connections as per the circuit diagram for non circulating current mode.
3. Connect 30V tapping of the transformer secondary to the power circuit.
4. Connect firing pulses from the firing circuit to their respective SCRs in power circuit.
5. Switch ON the MCB and now switch ON the trigger pulses by operate ON/OFF switch in the
firing circuit.
6. Observe the output voltage waveforms across load and devices us oscilloscope.
7. Note down the input voltage, firing angle, Output voltage and output circuit reading in the
tabular forms.
8. Repeat the same for different input voltage up to max. Voltage as provided in the isolation
transformer.
9. Draw the waveforms in the graph at firing angles 00, 450, 900, 1350 and 1800.
10. Repeat the same step for circulating current mode also.
88
17.7 Circuit diagram:
Non circulating current mode:
Circulating current mode:
17.8 TABULAR FORMS:
For non circulating current mode
S.No.
Input voltage (V)
Firing
Output voltage
Ton +Toff
angle ()
(V)
(sec)
Firing
Output voltage
Ton +Toff
angle ()
(V)
(sec)
For circulating current mode:
S.No.
Input voltage (V)
89
17.9RESULT:
Thus the single phase dual converter with RL for circulating and non circulating mode of
current was studied and also plotted the waveforms of different firing angles.
17.10PRE LAB QUESTIONS:1. What is the four quadrant operation?
2. What will happen if the firing angle is greater than 90 degrees?
3. What are modes of operation carried out in dual converter?
4. What are the advantages of dual converter?
17.11POST LAB QUESTIONS:1. If firing angle is greater than 90 degrees, the inverter circuit formed is called as?
2. How to change the circulating to non circulating current mode?
3. Write advantages of dual converter?
4. What are the drawbacks of the dual converter?
90