Power Electronics Lab Manual (2012-2013)

7/30/2019 Power Electronics Lab Manual (2012-2013)

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PADMASRI Dr. B. V. RAJU INSTITUTE OF TECHNOLOGY

VISHNUPUR, NARSAPUR, MEDAK (Dist)

ANDHRA PRADESH, INDIA-502313www.bvrit.ac.in

Department of

ELECTRICAL AND ELECTRONICS ENGINEERING

III-B.Tech II-SEMISTER

POWER ELECTRONICS & SIMULATIONLAB MANUAL

(2012-2013)

Prepared by

Sr.Asst.Professor,

EEED-BVRIT


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POWER ELECTRONICS AND SIMULATION LAB CODE

1. Students should report to the concerned labs as per the time table schedule.

2. Students who turn up late to the labs will in no case be permitted to perform theexperiment scheduled for the day.

3. After completion of the experiment, certification of the concerned staff in-charge in theobservation book is necessary.

4. Students should bring a note book of about 100 pages and should enter thereadings/observations into the note book while performing the experiment.

5. The record of observations along with the detailed experimental procedure of theexperiment performed in the immediate last session should be submitted and certified bythe staff member in-charge.

6. Not more than three students in a group are permitted to perform the experiment on asetup.

7. The group-wise division made in the beginning should be adhered to, and no mix up of student among different groups will be permitted later.

8. The components required pertaining to the experiment should be collected from stores in-charge after duly filling in the requisition form.

9. When the experiment is completed, students should disconnect the setup made by them,and should return all the components/instruments taken for the purpose.

10. Any damage of the equipment or burn-out of components will be viewed seriously eitherby putting penalty or by dismissing the total group of students from the lab for thesemester/year.

11. Students should be present in the labs for the total scheduled duration.

12. Students are required to prepare thoroughly to perform the experiment before coming toLaboratory.

13. Procedure sheets/data sheets provided to the students groups should be maintainedneatly and to be returned after the experiment.


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POWER ELECTRONICS AND SIMULATION LAB

Objectives:

The Power Electronics and Simulation Laboratory is a unique opportunity

for you to design and build. Power electronic circuits are the backbone of almost

every modern convenience. Automobiles, cell-phones, laptop and desktop

computers, television sets, and kitchen appliances, among many other systems,

require power electronics circuits to convert electrical energy to a useful form.

The creation of a successful power electronic circuit almost always requires

more than the application of a set of analytical techniques. The most elegant

examples are crafted by engineers who have a rich understanding of how to make

trade-offs amongst all the parts of a system, e.g., thermal, mechanical, electrical,

and sometimes software. For this reason, we make special efforts to expose you to

a huge number of demonstrations developed from a wide range of engineering

disciplines, and to provide exciting laboratory experiences that let you try the

techniques you learn on practical hardware.


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POWER ELECTRONICS AND SIMULATION LAB

Any Eight of the Experiments in Power Electronics Lab

1. Study of Characteristics of SCR, MOSFET & IGBT

2. Gate firing circuits for SCRs

3. Single Phase AC Voltage Controller with R and RL Loads

4. Single Phase fully controlled bridge converter with R 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 Cyclo converter with R and RL loads

9. Single Phase Half controlled converter with R load

10. Three Phase half controlled bridge converter with R-load

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

Any two simulation experiments with PSPICE/PSIM

14. PSPICE simulation of single-phase full converter using RLE loads and single-phase ACvoltage controller using RLE loads.

15. PSPICE simulation of resonant pulse commutation circuit and Buck chopper.

16. PSPICE simulation of single phase Inverter with PWM control.

REFERENCE BOOKS:1. Simulation of Electric and Electronic circuits using PSPICE by M.H.Rashid, M/s

PHI Publications.

2. PSPICE A/D users manual Microsim, USA.

3. PSPICE reference guide Microsim, USA.


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CONTENTS

POWER ELECTRONICS AND SIMULATION LAB MANUAL

S.NO. NAME OF THE EXPERIMENT Page No

1 Study of characteristics of SCR, MOSFET and IGBT. 110

2 Forced commutation circuits (class A, B, C and D). 11 16

3 Single phase AC voltage controller with R & RL loads. 17 23

4 Single phase fully controlled bridge converter with R & RL loads. 24 30

5 Single phase half controlled converter with R& RL load. 31 36

6 Single phase Cyclo converter with R& RL loads. 37 43

7 Study of gate firing circuits 44 49

8 DC Jones chopper with R and RL Loads 50 54

9 Single Phase Parallel, inverter with R and RL loads 55 59

10 Three Phase half controlled bridge converter with Rload and RLloads 60 62

SIMULATION EXPERIMENTS

11 PSPICE simulation of single phase full converter using RLE loads and single phase AC voltage controller using RLE loads.

63 67

12 PSPICE simulation of resonant pulse commutation circuit and Buck chopper

68 70

13 PSPICE simulation of single phase Inverter with PWM control. 71 74

ADDITIONAL EXPERIMENTS

14 Speed control of dc shunt motor using half controlled converter 75 77

15 Speed control of I Induction motor using AC Voltage controller 78 79


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Power Electronics and Simulation Lab Manual, EEE Department, BVRIT

1

1. STUDY OF CHARACTERISTICS OF SCR, MOSFET AND IGBT

AIM : To study various characteristics of SCR, MOSFET and IGBT.

APPARATUS:

S.No EQUIPMENT Qty

1. SCR,MOSFET AND IGBTKIT

1

2. PATCH CARDS 1 set

THEORY:

Silicon Controlled Rectifier: Silicon Controlled Rectifier is a four-layer three junction p-n-p-nswitching device. It has three terminals, Anode, cathode and gate. In normal operation of thyristor anode held with high positive potential with respect to cathode and gate has a small

positive with respect to cathode.

When Anode is made positive with respect to cathode and switch is open in the gate circuit,then p-n junction j1 and j3 are forward biased ,where as j2 becomes wider and j1 thinner at j1and j3. There is no base current in transistor t2 and hence that of t1.under such conditions theSCR is in a state of blocking forward direction. If now gate is made positive w.r.t. cathode or switch is closed , a small gate current will flow through junction j2 as a result anode starts flowsif anode current is greater than latching current of SCR.SCR is forward conduction state or simply SCR is closed state.

MOSFET: A Power MOSFET has three terminal called drain, source and gate. MOSFET is avoltage controlled device. As its operation depends upon the flow of majority carriers only.MOSFET is uni polar device. The control signal or gate current less than a BJT. This is becauseof fact that gate circuit impedance in MOSFET is very high of the order of 10 9 ohm. This larger impedance permits the MOSFET gate be driven directly from microelectronic circuits. Power MOSFETs are now finding increasing applications in low-power high frequency converters.

IGBT: IGBT is a new development in the area of Power MOSFET Technology. This devicecombines into its the advantages of both MOSFET and BJT. So an IGBT has high inputimpedance like a MOSFET and low-on-state power loss in a BJT.IGBT is also known as metaloxide insulated gate transistor (MOSIGT). Conductively modulated field effect transistor


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(COMFET) or gain modulated FET (GEMFET). It was initially called insulated gatetransistor(IGT).

CIRCUIT DIAGRAM:

SCR CHARACTERISTICS:

++

+

(0-200mA)

IG

(0-15V)

(0-35V)

(0-50V) VGK

A

G K

IA

VAK V

A

VAK

2.5K /25W

(0-20mA)

A


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MOSFETCHARACTERISTICS:

IGBT CHARACTERISTICS:

+

+

(0-200mA)

(0-35V)

(0-15V)

(0-20V) VCC

C

G

E

ID

VCE V

A

VGG

2.5K /25W

+

(0-20V)

VBE V

+

+

(0-200mA)

(0-35V)

(0-15V)

(0-50V) VDD

DG

S

ID

VDS V

A

VGS

2.5K /25W

+

(0-20V)

VGS V


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PROCEDURE:


A) Forward V-I Characteristics:

1. The connections are made as shown in the circuit diagram.

2. Switch on the power supply .Apply constant V AK voltage say 10V varying V AA

3. Gradually increase the gate current till the SCR becomes on i.e. V AK and I A

4. Now V AK is increased gradually and I A noted for two to three readings,

5. Steps 3 to 4 are repeated for another values of V AK say 30V.

6.

Tabulate the readings in the tabule.7. Plot a graph of V AK versus I A for different(two) values of I G

B) Reverse V-I Characteristics :

1. Now reverse the polarities of the anode voltage source.

2. Open the switch in the gate circuit.

3. Note down the readings of anode voltage and current by increasing the value of voltage source in the anode circuit.

C) Gate Characteristics:

1. Now open the switch in the anode circuit.

2. Set the gate circuit voltage source and anode circuit voltage source as per the givenvalue.

3. Note down the readings of gate voltage and gate current by reducing the value of gateside rheostat.

MOSFET CHARACTERISTICS:

A) OUTPUT CHARACTERISTICS:



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2. Switch on the Supply. Keep V DS say 10V vary V GS note down the range of V GS for which drain current is varying for constant V GS

3. Keep V GS constant (V GS must be within the range determined by step2)

4. Vary V DS in steps ,note down corresponding I D

5. Step4 is repeated for different V GS

6. Tabulate the readings in the table.

7. Plot a graph of I D against V DS for different V GS

B) TRANSFER CHARACTERISTICS:


2. Switch on the regulated power supplies. Keep V DS constant say 10V. Vary V GS in steps,note down the corresponding I D


4. Plot a graph of I D against V GS


A) OUTPUT CHARACTERISTICS:

1. Connections are made as shown in the circuit diagram

2. Switch on power supply. Keep V GE say 5v, vary V GE note down the range of V GE for which collector current is varying for constant V GE.

3. Keep V GE constant ( V GE must be within the range )

4. Vary V CE in steps ,note down corresponding I C

5. Adjust V GE to constant while doing step4.

6.

Step4 is repeated for different V GE .7. Tabulate the readings in the table.

8. Plot a graph of I C against V CE for different V GE

B) TRANSFER CHARACTERISTICS:


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1. Connections are made as shown in the circuit diagram

2. Switch on the power supply. Keep V CE constant. Vary V GE in steps .note downcorresponding I C

3. Adjust V CE to constant while doing step2.


5. Plot a graph of I C against V GE for the constant V CE


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TABULAR COLUMN:


A) FORWARD V-I CHARACTERISTICS B) REVERSE V-I CHARACTERISTICS

S.NO.IG1= mA I G2= mA

VAK =V

IA= mA V AK =V

IA= mA

C) GATE CHARACTERISTICS:

S.No. V G IG

S .NO. V AK = V I A= mA


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A) OUTPUT CHARACTERISTICS B) TRANSFER CHARACTERISTICS

S.NO.VGS1 = V V GS2= V

VDS=V

ID= mA V DS=V

ID= mA


A) OUTPUT CHARACTERISTICS B) TRANSFER CHARACTERISTICS

S.NO. V DS1 = V

VGS= V I D = mA

S.NO.VGE1 = V V GE2 = V

VBE= V I C= mA V BE= V I C= mA

S.NO.VCE= V

VGE= V I C = mA


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MODEL GRAPHS:


FORWARD AND REVERSE CHARACTERISTICS: Gate characteristics:


VGS

ID

MOSFET Transfer Characteristics

VGST

VGS4 >V GS3 >V GS2

VGS2

VGS1

VGS3

VGS4

VDS

ID

MOSFET V-I Characteristics

I

Vg


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RESULT: Output and Transfer Characteristics of SCR, MOSFET and IGBT are studied

VGE4 >V GE3 >V GE2 >V GE1

IGBT


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2. STUDY OF FORCED COMMUTATION CIRCUITS

AIM : To Verify the different types of forced commutation circuits by connecting

a resistive load.

APPARATUS:

S.No EQUIPMENT Qty

1. Forced commutation Kit 1

2. Regulated Power Supply 1

3. Rheostat 2

4. CRO 1

5. Patch cards

THEORY: Commutation is the process of turning off the SCR and it normally causes thetransfer of current flow to other parts of circuit. Commutation can be divided into

a) Natural commutation

b) Forced commutation

a) Natural commutation: If the source voltage AC the SCR current goes through a natural zeroand reverse voltage appears across the SCR. The device is automatically turns off due to thenatural behavior of the source voltage. This is known as natural commutation or linecommutation.

b) Forced commutation: In some SCR circuits the input voltage is DC and the forward current

of the SCR is DC and the forward current of the SCR is forced to zero by external or additional circuitry called as commutation circuitry to turn off SCR. This Technique is calledforced commutation and normally applied in DC to DC converters .


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Forced Commutation circuits can be classified as

i. Class-A Commutation (Series resonant commutation circuit)

ii. Class-B Commutation (Parallel resonant commutation circuit)

iii. Class-C Commutation ( Complementary commutation circuit)

iv. Class-D Commutation (Auxiliary Commutation)

v. Class-E Commutation (External Pulse Commutation)

CIRCUIT DIAGRAM:

CLASS-A COMMUTATION: CLASS-B COMMUTATION:

CLASS-C COMMUTATION: CLASS-D COMMUTATION:

R

D

+ TA

L

T1

(0-30V)T1 T2

C

R 1 R 2

(0-15V)

R

LT

(0-15V)

C

To CRO

R

L

T1

(0-15V) C To CRO


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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 acrossload by varying the frequency potentiometer.

4. Repeat the same for different values of L,C and R.

CLASS-B COMMUTATION:


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 acrossload 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:


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:



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2. Connect T1 and T2 gate pulse from the firing circuit to the corresponding SCRs 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 theload 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 inductanceand capacitance.

CLASS-E COMMUTATION:

1. Connect the circuit as shown in the circuit.2. Connect the trigger output T1 from the firing circuit to the SCR.

3. Connect T2 to the Transistor base and emitter points

4. Switch on the Power Supply and External DC supply.

5. Switch on the trigger output and observe and note down waveforms. Repeat the

Same by varying frequency and duty cycle.

MODEL GRAPHS:

CLASS-A COMMUTATION:


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CLASS-B COMMUTATION:

CLASS-C COMMUTATION:


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CLASS-D COMMUTATION:

CLASS-E COMMUTATION:

RESULT: The operations of class A, B, C, D and E are observed.


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3. SINGLE PHASE AC VOLTAGE CONTROLLER WITH R & RL LOADS

AIM : To Verify the operation of single phase AC Voltage controller with R and RL Loads and

to observe the output and input waveforms

APPARATUS:

S.No EQUIPMENT Qty

1. I- Transformer 1

2. I- AC voltage controller power circuit with firing unit

1

3. Voltmeters(MI meters) 2

4. Rheostat 1

5. Inductive load 1

6. CRO with (1:10) Probe 1

7 Patch cards

THEORY: AC voltage controllers are thyristor based devices ,which converts the fixed Acvoltage into variable AC voltage with same frequency .The circuit diagram of Single phase ACvoltage controller is shown in figure .It consists of two SCRs connected in anti parallel. Theinput and output voltage waveforms are also shown. The SCRs are gate controlled and gate

pulses are obtained from firing unit.

A) For R-Load: For the first half cycle of input voltage waveform SCR T1 conducts and givescontrolled output to load. During the other half cycle of input voltage waveform SCR T2conducts .During the Positive half cycle T1 is triggered at a firing angle of wt= .T1 startsconducting and source voltage is applied to the load from to . At wt= both V o and I o

falls to zero. Just after wt= , T1 is reverse biased and therefore it is turned off by self commutation. During the negative half cycle of T2 is triggered at wt= +, then T2conducts from wt = +

2/1}/]2sin)2/1(){[( += phrmso V V


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Where V orms is the theoretical RMS value of the output voltage,

V ph is the phase voltage of the input voltage and is the firing angle

B) For RL Load:

During the first half cycle wt = 0 to SCR T1 is forward biased and istriggered at wt= and output current starts building up through load .At wt= , load andsource voltage are zero. But the output current is not zero because of inductive load. Atwt=( >), the load current reduces to zero, angle is called extinction angle. After wt =, SCR T1 is reverse biased, but does not turn off because the output current is not zero.

At wt= , only when output current is zero T1 turns off.

During the negative half cycle SCR T2 is forward biased and is triggered at

wt = +. The output current flows through the load in reverse direction. The operationof SCR T2 is similar as that of SCR T1 during the period wt = + to wt = (2 -) but inthe negative direction. At wt= ( 2 -) the SCR t2 is commutated and the next positivehalf cycle will be regulated by SCR T1. In this way the AC Voltage controller will beuseful for regulating the AC voltage.

2/1}2/)]2sin)2/1(2)(sin2/1(){[( += phorms V V

Theoretically the value of Extinction angle can be calculated by

= (+); Where =tan -1(wL/R)


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T2 To CRO1-

AC Supply

R

N

Ph

T1

VV

Fig-1 Single Phase AC Voltage controller with R-load

To CRO1-

AC Supply

L

R

N

Ph

T2

T1

VV

Fig-2 Single Phase AC Voltage controller with RL-load

CIRCUIT DIAGRAM:

AC VOLTAGE CONTROLLER:


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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 CRO and calibrate it with the input voltage.

5. Switch on the power circuit and firing circuit.

6. Observe the output voltage waveform in the CRO.

7.

Note down the reading of from the CRO and V o from the voltmeter 8. Also calculate the theoretical value of output voltage from the formula and

compare it with the practical value of the output voltage, which is observed fromthe voltmeter.

9. Repeat the above process from step 6 to 8 for various firing angles.

B). For RL-Load:

1. Switch off the power supply and connect an inductance of given value in series

with the load resistance.2. Repeat steps 2 to 9 in this case and also note down the reading of .

TABULAR COLUMN:

A) For R-Load:

The input voltage V ph = V (As given by the instructor)

Value of load resistance R L= (As given by the instructor)CRO calibration: 180 degrees = msec = radians

S.NO. Firing angle( )in milli seconds

Firing angle( )in degrees

Firing angle( )in radians

Vo (Practical ) V o (Theoritical)


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A) For RL-Load:


Value of load resistance R L= (As given by the instructor)

Value of Load inductance L= mH(As given by the instructor)

CRO calibration: 180 degrees = msec = radians

Theoretical Extinction angle = (in msec) = (degrees) = (radians)

Practical Extinction angle = (in msec) = (degrees) = (radians)





MODEL GRAPHS:

With R-Load:


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With RL-Load:


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RESULT: The operation of I- ac voltage controller with R&RL loads is verified and

the theoretical and practical values of output voltages with R and RL loads are found.


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4. SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTERWITH R & RL LOAD

AIM : To obtain controlled output waveforms of a single phase fully controlled bridge

Converter with R and RL Loads.

APPARATUS:

S.No EQUIPMENT Qty

1. I- Transformer 1

2. I- fully controlled power circuit with firing unit

1

3. Voltmeter(MI meter) 1

4. Voltmeter(MC meter) 1

5. Rheostat 1

6. Inductive load 1

7 CRO with (1:10) Probe 1

8. Patch cards

THEORY:

A) For R-Load: A fully controlled bridge converter using four SCRs is shown in the circuitdiagram. In the bridge circuit diagonally opposite pair of SCRs are made to conduct andare commutated simultaneously. During the first positive half cycle SCRs T1 and T2 areforward biased and they are triggered simultaneously at wt = then the current flowingthrough the path A-T1-R-T2-B. During the negative half cycle of the input SCRs T3 andT4 are forward biased and they are triggered at wt= ( +) simultaneously then the currentflows through B-T3-R-T4-A. Thyristors T1,T2 and T3,T4 are triggered at same firingangle in each positive and negative half cycle of the input voltage respectively.


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When the output voltage falls to zero, the output current also falls to zero because of resistive load .Hence SCRs T1, T2 in positive half cycle and T3,T4 innegative half cycle turn off by natural commutation.

The related voltage and current wave forms are shown in the diagram.

The theoretical value of the average DC output voltage can be calculated by

Voth= (V m/)(1+cos ).

Where V oth is the theoretical value of the output voltage

Vm is the maximum value of the AC input voltage and

is the firing angle.

B) For RL-Load:

A fully controlled bridge converter using four SCRs is shown in the circuit diagram. Toconduct the SCRs simultaneously firing of SCRs T1,T2 in the first half cycle and T3,T4in the next half cycle is necessary. To ensure this both T1,T2 are fired from the samefiring angle.

As shown in the diagram when wt= , SCRs T1, T2 are triggered simultaneously.The current flow through A-T1-R-L-T2-B.Supply voltage from this instant appearsacross output terminals and forces the current through load. At wt= ,the output voltage

tends to reverse its direction where as the output current tries to flows on the samedirection because of inductive load. The output current becomes zero at a angle of wt= .

At an angle wt=( +) SCRs T 3 ,T4 are triggered, with this negative line voltagereverse biases SCRs T1 and T2 hence the SCRs T1 and T2 are commutated.Now thecurrent flows through the path B-T3-R-L-T4-A.This continue in every half cycle and weget output voltage as shown in waveforms.

The theoretical value of the average DC output voltage can be calculated by

)cos)(cos/2( = mOTH V V


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Fig-1

To CRO

T3

T2

R

N

1-, 230VAC Supply

Ph

V V

T1

T4

To CRO

T3

T2

N

1-, 230VAC Supply

Ph

V V

T1

T4 L

R

Fig-2

CIRCUIT DIAGRAM:

With R-Load:

With RL-Load:


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PROCEDURE:

B) For R-Load:




4. Switch ON the CRO and calibrate it with the input voltage.

5. Switch on the power circuit and firing circuit.

6. Observe the output voltage waveform in the CRO.

7.

Note down the reading of from the CRO and V o from the voltmeter 8. Also calculate the theoretical value of output voltage from the formula and

compare it with the practical value of the output voltage, which is observedfrom the voltmeter.

9. Repeat the above process from step 6 to 8 for various firing angles.

B). For RL-Load:

1. Switch off the power supply and connect an inductance of given value in series

with the load resistance.2. Repeat steps 2 to 9 in this case and also note down the reading of .


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MODEL GRAPHS:

With R-Load:

With RLLoad:


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TABULAR COLUMN:

B) For R-Load:








B) For RL-Load:




Theoretical Extinction angle = (in msec) = (degrees) = (radians)

Practical Extinction angle = (in msec) = (degrees) = (radians)






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RESULT: The operation of I- fully controller converter is verified and the theoreticaland practical values of output voltages are found ,both for R and RL loads at different

firing angles.


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5. SINGLE PHASE HALF CONTROLLED BRIDGE CONVERTERWITH R & RL LOAD

AIM: To obtain the output waveform of single phase half controlled bridge converter with R and RL Loads.

APPARATUS:

S.No Name of the Equipment Type Ramge Quantity1. Single phase half

controlled converter power circuit

1

2. Firing Unit 13. Voltmeter MI (0-60V) 1MC (0-50V) 1

4. 1:1 Isolation Transformer 1KVA 15. Rheostat Wire wound 100ohm/5A 16. Inductive load 0-150mH 17. CRO8 Patch Chords

THEORY:

Single Phase half wave controlled bridge converter with R&RL loads are shown in the diagram.

RLoad:

During the positive half cycle of AC supply SCR T1 and diode D1 are forward biased.

The SCR T1 is triggered at a firing angle t=, the output current flows through hthe path A-T1-R-D1-B. The load current will flow until T1 is commutated by reversal of supply att=. During The nagative half cycle of AC supply SCR T2 and diode D2 are forward biased.When the SCR T2 is triggered at angle t=(+), the output current would flow through the pathB-T2-R-D2-A. This current continues up to t=2, at this angle the SCR T2 is commutated due


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to reversal of the supply voltage. The theoretical average vale of DC output voltage can becalculated by,

Where Vo TH is the theoretical average vale of DC output voltage

Vm is the maximum value of AC input voltage and

= is the firing angle

RL-Load:

The main difference between the operation of the circuit with a complex load, and with a

purely resistive load is that at end of each half-cycle of the supply voltage, the current flow is

maintained in the load circuit by the inductance of the load. The thyristor that has been

conducting, say SCR1, continues to conduct, but current transfers from diode D2 to D1 so that

the inductive back emf of the load drives current through the bridge without including the

reverse supply voltage. During this part of the cycle, the load current decays exponentially and is

unaffected by the supply voltage. When SCR2 is triggered, SCR1 is reverse biased by the supply

voltage and turns off. Current now flows from the supply through SCR2 and diode D1 into the

load. SCR1 is triggered in the next half-cycle and the sequence is repeated.

The theoretical average vale of DC output voltage can be calculated by,

Where extinction angle =+

And can be calculated as


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Fig-1 for R-load

To CRO

T3

D2

R

N

1-, 230VAC Supply

Ph

V V

T1

D1

To CRO

T3

D2

N

1-, 230VAC Supply

Ph

V V

T1

D1 L

R

Fig-2 for RL-load

PROCEDURE:

R-load:

1. Make connections as per the circuit diagram.2. Verify the connections from the lab instructor before switching ON the supply.3. Keep the rheostat position and variac position as the value given by the lab instructor.4. Switch ON the CRO and calibrate it with the input voltage.5. Switch ON the power circuit and firing circuit.


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6. Observe the output voltage wave form in the CRO.7. Note down the readings of from the CRO Vo from the voltmeter.8. Also calculate the theoretical value of the output voltage from the formula and

compare it with the practical value of the output voltage, which is observed from thevoltmeter.

9. Repeat the above process for various firing angle.

RL-load:

10. Switch off the supply and connect an inductance of given value in series with the loadresistance.

11. Repeat steps 2 to 9 and also note down the readings of .

OBSERVATIONS:

For R-Load:

Input voltage Vph=

Load resistance R=

S.No Firing

angle( ) inmsec

Firing angle

in Degrees

Firing angle

in radians

Vo

(theoretical)

Vo

(practical)

RL-Load:

Input voltage Vph=

Load resistance R=

Value of Inductance L=

Theoretical Extinction angle =

Practical Extinction angle =


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S.No Firingangle( ) in

msec

Firing anglein Degrees

Firing anglein radians

Vo(theoretical)

Vo(practical)

Model Graphs:

R-Load:

RL Loads


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Result:

The operation of Single Phase half controlled converter is verified and the theoretical and practical values of output voltage are found, both for R and RL loads.


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6. SINGLE PHASE CYCLO CONVERTER WITH R & RL LOADS

AIM : To verify the operation of single phase Cyclo Converter with R and RL Loads and to

observe the output and input waveforms

APPARATUS:

S.No EQUIPMENT Qty

1. I- Center tappedTransformer

1

2. I- Cyclo Converter power circuit with firing unit

1

3. Rheostat 1

4. Inductive load 1

5. Voltmeter(MI) 1


8. Patch cards 1 set

THEORY

The circuit diagram of 1- cyclo converter with R and RL load are shown in fig.

Construction ally there are four SCRs T 1, T2, T3 &T 4.Out of them T 1, T2 are responsible for generating positive halves forming the positive group. The other two T 3, T4 are responsible for negative haves forming negative group. This configuration and waveforms are shown for and1/3 of the supply frequency. Natural commutation process is used to turn off the SCRs.

A) For R-Load: During the half cycle when point A is positive with respect to O, SCR T 1 isin conducting mode and is triggered at wt = then current flows through positive pointA-T 1-load-negative O. In the negative half cycle when B point is positive with respect tothe point O,SCR T 1 is automatically turned off due to natural commutation and SCR T 2 istriggered at wt = +. In this condition the current flows through B-T 2-load-O. The flow of


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the current direction is same as in the first case. After two positive half cycles of loadvoltage and load current SCR T 4 is gated at wt=2 + when O is positive with respect to B.In this condition the load current flows through O-load-T 4-B.Thus the direction of loadcurrent is reversed. In the next half cycle when O is positive with respect to A whenwt=3 , T4 turnoff due to natural commutation and at wt=3 + T3 is triggered. In thiscondition the load current flows through O-load-T 3-A. The direction of load current issame as previous case. In this manner two negative half cycles of load voltage and loadcurrent, equal to the number of two positive half cycles are generated. Now T 1 is againtriggered to fabricate further two positive half cycles of load voltage and so on. Like thisthe input frequency 50Hz is reduced to at the output across the load. The input andoutput waveforms are shown in figure.

The frequency of the output voltage can be calculated by:

Frequency ( f o )=(Time period)-1

B) For RL-Load:-

When A is positive with respect to O forward biased SCR T 1 is triggered at wt= and thecurrent start to flow through A-T 1-R-L-O. Load voltage becomes zero at wt= but loadcurrent will not become zero at this angle due to inductance. It becomes zero at wt = which is called extinction angle. So it is naturally commutated at wt= . After half cycle

point B positive with respect to point O. Now at angle wt= +. T 2 is triggered and the loadcurrent takes path from B-T 2-R-L_o and its direction is positive as in the previous case.The load current decays zero at wt = + and SCR T

2is naturally commutated.

In the half cycle when O is positive with respect to B point, T 4 is triggered instead of T 1 at an angle of wt= (2 +). Now the load current flows through O-L-R-T 4-B but thedirection of load current reversed. When the load current becomes zero at an angle wt=(2+) , T 4 naturally commutated because the voltage is already reversed at wt = 3 .Whenwt = (3 +) and point O, is positive with respect to point A,T 3 is triggered then the currentflows through O-L-R-T 3-A , and the direction of load current is same in previous case. Inthe next half cycle again T 1 will triggered like this we get one cycle of output frequency for two cycles of input frequency, when the frequency division switch is at 2. The waveformsof load voltage and load current are shown in fig.

The frequency of load voltage can be calculated by f o=(Time period) -1


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CIRCUIT DIAGRAMS:

center tappedtransformer

T4

T3 To CRO

N

Ph

T1

T2 L

R 1-, 230V50HzAC Supply

Fig-2Fig2Single phase cyclo converter with RLload

center tappedtransformer

1- , 230V 50HzAC Supply

T4

T3 To CRO

R

N

Ph

T1

T2

Fig1Single phase cyclo converter with Rload


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PROCEDURE:

A) For R-Load:




4. Switch ON the supply and note down the frequency of input voltage from theCRO.

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 frequencydivision setting

7. Repeat the above process from step 5 to 6 for frequency division of 3 and 4.

B). For RL-Load:


2. Connect an inductance of given value in series with the load resistance.



5. Switch ON the supply and note down the frequency of input voltage from theCRO.

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


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7. Calculate the practical value of output frequency by reciprocating the value of time period and theoretical value of frequency will be found from frequencydivision setting

8. Repeat the above process from step 5 to 6 for frequency division of 3 and 4.

TABULAR COLUMN:

C) For R-Load:



Input frequency = Hz

S.NO. Frequencydivision


Time period inmsec

Frequency(practical)

Frequency

(theoretical)

C) For RL-Load:



Value of Load inductance L= mH(As given by the instructor)

S.NO. Frequencydivision


Time period inmsec

Frequency(practical)

Frequency

(theoretical)


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MODEL GRAPHS:

1/2f cycloconverter waveforms


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RESULT: The operation of I- cyclo converter is verified and the theoretical and practical values of output frequencies at different frequency divisions are found both for R & RL loads


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7. STUDY OF GATE FIRING CIRCUITS

AIM : To observe the output waveforms of resistance, Resistance- Capacitance and UJT gatefiring Circuits of SCR.

.

APPARATUS:

S.No EQUIPMENT Qty

1. R-firing circuit Kit 1

2. RC firing circuit kit 1

3. UJT firing circuit kit 1


5. Patch cards 1 set

THEORY:

R-firing Circuit:

Uni-Junction Transistor: UJT exhibits negative resistance characteristics; it can be used asrelaxation oscillator. The external characteristics R B1 and R B2 are resistances which are small incomparison with internal resistances R 1 and R 2 of the UJT base. The emitter potential V is varieddepending on the charging rate of capacitance C. The charging resistance R c should be such thatthe load line intersects the device only in the negative resistance region. is called as theintrinsic standoff ratio. It is defined as

)/()( 211 B B B R R R +=

UJT is a highly efficient switch .Its switching time is in a range of nano seconds. Since UJTexhibits negative resistance characteristics it can be used as a relaxation oscillator. The rise time


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output pulse will depend on the switching speed of the UJT and duration will be proportional tothe time constant R B1C of the discharge circuit.

The output pulses of UJT are identical in magnitude and time period

)))1/(1(ln( = RC T

The value of is specified for each device .For UJT =0.63.

CIRCUIT DIAGRAM:

R-firing circuit:

RC-firing circuit:

100E / 10W

To CRO

A

G

K

1-, 230V50HzAC Supply

N

Ph

Half Wave RC Triggering

D

R 1

R 2

R

VL

A

G

K

1- AC Supply

N

Ph


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UJT firing circuit:

PROCEDURE FOR RFIRING CIRCUIT:

1.Turn the potentiometer fully anti clockwise, connect load as shown by jumpers,

2. Connect SCR in the ckt by using shorting links as shown by the dashed lines.

3. Connect the Oscilloscope across the load.

4. Vary the firing angle and observe the waveforms on the CRO

5. Draw the corresponding waveforms.

VBB

Vdc

C1 C3 C2

B1

B2

R B2 R

UJT Firing circuit:

To CRO

100E / 10W

To CRO

A

G

K D2

D3

1-, 230V50HzAC Supply

N

Ph

D1

D4

Full Wave RC Triggering


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PROCEDURE FOR RC FIRING CKT:

1. Connect the load and SCR in the CKT by jumpers as shown in the ckt diagram. 2. Tune the potentiometer fully anticlockwise. 3. Connect oscilloscope in the load divider and switch on the power supply. 4. Vary the firing angle and draw the corresponding waveforms. PROCEDURE:

UJT firing circuit:


2. Connect a capacitor C 1 in series with variable resistance.

3. Place the knob of variable resistance at either of the extreme positions and place one capacitor inseries and take the reading of firing angle at that time period. i.e. total time is equal to the sum of turn off and turn on times.

4. Vary the resistance to the other extreme position and note down the readings.

5. Replace the capacitor with another one and calculate the RC from noted reading.

6. Calculate the R Lmax and R Lmin from the above readings.

MODEL CALCULATIONS:

)/()( 211 B B B R R R += =0.63 for UJT

)))1/(1(ln( = RC T

Model Graphs of R firing circuit:


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Model Graphs of RC gate firing circuit:


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Model Graphs of UJT firing circuit:

RESULT: The waveforms across the load and device for different values of firing angles are studied.

8. DC JONES CHOPPER WITH R& RL LOADS

AIM: : To obtain the output waveform of single phase fully controlled bridge converter

with R and RL Loads.

APPARATUS:

S.No Name of the Equipment Type Ramge Quantity

1. Single phase fullycontrolled converter power

circuit 1

2. Firing Unit 1


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3. Voltmeter MI (0-60V) 1

MC (0-50V) 1

4. 1:1 Isolation Transformer 1KVA 15. Rheostat Wire wound 100ohm/5A 1

6. Inductive load 0-150mH 1

7. CRO

8 Patch Chords

THEORY:

The Jones Chopper circuit is another example of class D commutation. In this circuit

SCR T M is the main thyristor, where as SCR T A, capacitor C, diode D1 and auto transformer

forms the commutating circuit for the main thyristor TM. Therefore the special feature of this

circuit is the tapped auto T/F through a portion of which the load current flows L1 and L2 are

closely coupled so that the capacitor always gets sufficient energy to turn off the main SCR TM.

Let us assume that initially capacitor C is charged to a voltage Edc with the polarity

shown SCR TM is triggered current flows through the path CA-TM-L1-D1-CB and capacitor C

charges to opposite polarity i.e., plate B positive and plate A negative, however diode D1

prevents further oscillation of the resonating L2C circuit. Hence capacitor C retains its charge

until SCR TA is triggered.

Now, SCR TA is triggered current flows through the path CB-TA-TM-CA. Therefore,

discharge of capacitor C reverse biases SCR TM and turns it off. The capacitor again charges upwith plate A positive and SCR TA turns off because the current through it falls below the

holding current value when capacitor C is recharged.


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The cycle repeats when SCR TM is again triggered. The use of autotransformer involves

that whenever current is delivered from dc source to the load, a voltage is induced in L1 in the

correct polarity for changing the commutating capacitor to a voltage higher than Edc. Thus the

autotransformer measurably enhances the reliability of the circuit.

The theoretical average value of the Dc output voltage can be found from

Where is the average value of the DC output voltage?

is the duty cycle and

is the average value of the DC input voltage

CIRCUIT DIAGRAMS:


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PROCEDURE:

Dm

D1

+ TA

L2L1

To CRO

T1

VDCSupply

Fig-2: Circuit Diagram of DC Jones Chopper with RL Load

L

R

D1

+ TA

L2L1

To CRO

T1

R VDC

Supply

Fig-1: Circuit Diagram of DC Jones Chopper with R Load


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(a) For R-Load:

1. Set the rheostat for given value, before connecting in the circuit.

2. Make the connections as per the circuit diagram.

3. Switch on the supply and set the input voltage to the given value.

4. For a particular firing angle note down the readings of ON time (Ton), OFF time (Toff),

Total time (T) from the CRO and the practical value of the output voltage from the

voltmeter.

5. Calculate the theoretical value of the output voltage from the data Ton, T and input

voltage.

6. Repeat the step 4 and 5 for a set of different duty cycle.

(b) For RL-load:

1. Now connect an inductance of given value and repeat the steps 3 to 6.

OBSERVATIONS:

(a) For R-Load:

The value of input voltage=

The value of load resistance=

S.No: Ton(ms) Toff(ms) Total

Time(ms)

Duty

cycle

Vo(practical) Vo(Theoretical)

(b) For RL-load:

The value of input voltage=

The value of load resistance=

The value of load inductance=


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S.No: Ton(ms) Toff(ms) Total

Time(ms)

Duty

cycle

Vo(practical) Vo(Theoretical)

Result:

The operation of DC Joness Chopper is verified and the theoretical and practical valuesof output voltage are found, both for R and RL loads.


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9. THREE PHASE HALF CONTROLLED BRIDGE CONVERTER WITHR& RL LOADS

AIM: To obtain the output waveforms of three phase full wave half controlled bridge rectifier with R and RL load and with or without commutating or freewheeling Diode.

APPARATUS:

S.No Name of the Equipment Type Ramge Quantity

1. There phase Half controlled bridge

converter power circuit 1

2. Firing Unit 1

3. Voltmeter MI (0-100V) 1

MC (0-100V) 1

4. 3-ph Variac 415V/(0-415V) 1

5. Rheostat Wire wound 100ohm/5A 1

6. Inductive load 0-150mH 1

7. CRO

8 Patch Chords

Theory :

For large power dc loads, 3-ph ac to dc converter are commonly used. The various typesof three phase controlled converter are 3-ph half wave converter, 3-ph half wave converter israrely used in industry because it introduces de component in the supply circuit. If diodes arereplaced by 3-thyristors, a semi converter bride is obtained.


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Free wheeling mode of operation of bridge connected rectifiers can be realized half of itsthyristor with diodes. Therefore, circuit of three phase half-controlled bridge converter containsthree thyristor in three arms and diodes in the other three arms.

For 600

thediscontinuous conduction mode occurs. It can be observed from the waveforms that the outputvoltage becomes zero during a part of the output voltage period, because of the free wheelingaction. It is easily noted from the waveforms that the freewheeling period is . Therefore

the supply current flows for the period ( -) in each half cycle. As increase the duration of thesupply current pulse decreases. Therefore, the harmonic content in the source current increasesas the firing angle increases.

For large firing angle delays, commutation failure may take place due to the limited timeavailable in symmetrical half controlled converter circuit configuration, if the current is assumedto be continuous. This may result in half weaving effect.

The theoretical output voltage can be calculated as

For R-load:

-----for continuous mode

------for discontinuous mode

For RL-load:


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Procedure:

1. Make the connections as per the circuit diagram.2. Verify the connections before switching on the supply3. Keep the rheostat position and variac positions as the values given by the instructor.4. Switch on power circuit and firing circuit.5. Switch on the CRO and calibrate it with input voltage.

6. Observe output voltage waveform on CRO.7. Note down readings of firing angle and output voltage.8. Also calculate theoretical and practical values of output voltages and compare.9. Repeat above steps for various firing angles.

10. For RL-load connect Inductance in series with resistance.

415V, 3- 550hz, ACB

To

L

R

T3

D1 D3

T2

D2

V

T1

R

415V, 3- 50hz, AC

Y

Fig-2

R

415V, 3- 550hz, ACB

To

T3

D1 D3

T2

D2

V

T1

R

415V, 3- 50hz, AC

Y

Fig-1


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11. Repeat the above steps.

OBSERVATIONS:

For R-load:

Input voltage Vph=

Load resistance R=


msec



Vo(theoretical)

Vo(practical)

RL-Load:

Input voltage Vph=

Load resistance R=Value of Inductance L=

Theoretical Extinction angle =

Practical Extinction angle =


msec



Vo(theoretical)

Vo(practical)


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Input Supply

Model Graphs

RESULT: Observed and drawn the output waveforms of 3phase half controlled bridge converter with R and RL loads.


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10. SINGLE PHASE PARALLEL INVERTER

AIM: To study and obtain the AC output voltage waveform of single phase parallel inverter with R & RL loads.

APPARATUS:

S. No Components Quantity

1 Single Phase Parallel Inverter Kit 01

2 Bulbs 230V/40W 02 3 CRO 01

4 Patch cords

5 Voltmeter(0 100V) MI 01

Theory:

The circuit diagram of 1-ph Parallel Inverter is shown in fig., SCR1 and SCR2 are mainthyristors. Supply voltage Vdc appears across the left half of the transformer primary windingOA. Terminal O is positive w.r.t.A. By transformer action terminal B will be at potential of 2Vdcw.r.t A. Thus capacitor C will get charged twice the supply voltage. The load voltage will be

positive and will have a magnitude V L . At the end of half period SCR2 is firing , capacitor Cwill be immediately apply a reverse voltage of 2Vdc across SCR1 and turns off it.

Similarly the Vdc applies to right half of the primary winding and capacitor gets chargedwith 2Vdc in reverse direction. Now the load voltage is negative and hence the current. Since thecommutating capacitor is in parallel with SCRs, so it is called parallel inverter.


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Circuit diagram:

PROCEDURE:

1. Make the connections as per the circuit diagram.2. Verify the connections before switching on the supply.

3. Remove the link across the terminals marked LINK.4. Place the load lamps at place.5. Now switch on the main supply.6. Observe the wave form at terminal TP-1 and TP2 with respect to ground terminal with

CRO by using 1:10 probe.7. Now place the connecting link across terminals marked LINK.8. Observe the output by glowing lamp.9. Observer the waveform at terminals marked TP-3 and TP-4 with respect to the ground

terminal.


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Model Graphs:

Model Graph

Result:

The function of single phase parallel inverter is studied.


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11 PSPICE SIMULATION OF SINGLE PHASE FULL CONVERTERAND SINGLE PHASE ACVC

Aim:

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 .

Apparatus : PSPICE Software

AC Model of SCR:

F1= P1Ig + P2Ia

= 50I g + 11I a


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Circuit diagram of single phase full converter:

Circuit 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)




R 2 4 10

L 4 5 20MH

C 2 11 793UF

RX 11 3 0.1


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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

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

Circuit diagram of single phase ACVC:


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Circuit file for Single phase ac voltage controller:

VS 10 0 SIN (0 169.7V 60HZ)



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


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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

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

Result :

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.


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12 PSPICE SIMULATION OF BUCK CHOPPER AND RESONANTPULSE COMMUTATION

Aim:

Study of resonant pulse commutation circuit and Buck chopper with PSPICE simulation

Apparatus: PSPICE Software

Circuit diagram of buck chopper

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


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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

Circuit diagram of buck converter

CIRCUIT MODEL FOR BUCK CHOPPER

VS 1 0 DC 110V

VY 1 2 DC 0V


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VG 7 3 PULSE (0V 20V 0 0.1NS 0.1NS 27.28US 50US

RB 7 6 250

LE 3 4 681.82UHCE 4 0 8.33UF IC=60V

L 4 8 40.91UH

R 8 5 3

VX 5 0 DC 0V

DM 0 3 DMOD

.MODEL DMOD D (IS=2.2E15 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

Result : PSPICE simulation of resonant pulse commutation circuit and Buck chopper is studied and output waveform are observed.


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13 PSPICE SIMULATION OF SINGLE PHASE INVERTER WITH PWMCONTROL

Aim : To study the output of single phase Inverter with PWM control using PSPICE simulation.

Apparatus: PSPICE Software

Circuit diagrams of single phase inverter with pwm control

(a) Circuit


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(b) PWM generator

(c) carrier and reference signals

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=2.2E15 BV=1800V TT=0)

Q1 2 7 3 QMOD

Q2 6 9 0 QMOD

Q3 2 11 6 QMOD

Q4 3 13 0 QMOD


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.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

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)


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.END

Result : PSPICE simulation of single phase Inverter with PWM control is studied and outputwaveforms are observed.


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14. CIRCUIT DIAGRAM FOR SPEED CONTROL OF DC SHUNT MOTORUSING HALF CONTROLLED CONVERTER

Aim:To control the speed of the DC Shunt motor using half controlled converter.

Apparatus :

Sno Name of Equipment Quantity

1 Single phase half controlled

Converter power circuit

1

2 Firing Unit 1

3 Voltmeter (060)V MI 1

4 Voltmeter (050)V MC 1

5 1KVA 1:1 Isolation Transformer 1

6 Tachometer 1

7 Patch Chords As required

Circuit Diagram:


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Procedure :

without load:

1. Make connections as per the circuit diagram. 2. Keeping the fairing angle pot at 180 degrees switch on the supply. 3. By varying firing angle pot note down the reading of voltmeter ammeter and speed of the

motor.

4. Plot the graph speed vs Firing angle.

With load:

1. Make connections as per the circuit diagram. 2. Keeping the fairing angle pot at 180 degrees switch on the supply. 3. By varying firing angle pot bring the motor to rated speed. 4. Put some load on the motor with the help of loading arrangement. 5. By decreasing the speed steps wise up to 90 degrees note down the readings of ammeter

voltmeter, speed and spring balances.

FIELD

+

+

0250V MC

+

+

F

M

FF

230 VAC

Supply

+DPST Switch

Fuse

V V

A

0300V

A

AA


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77

6. Plot the graph speed vs efficiencies.

Observation table:

Without load:

S.NO. Firing angle Volt meter reading Ammeter reading Speed.

With load:

S.NO. Firing angle

Volt meter reading

Ammeter reading

Speed. Load on motor

Torque Out put Efficiency

Result: The speed of the DC Shunt motor is controlled using half controlled converter.


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78

(0-5)A

(0-3000 V

S

(0-3000 V

1- 230V50 Hz

ACSupply

Ph

N

DPST

1-230v IsolatedTransformer

V

A

IM

Brake Drum

V

15. Circuit Diagram for Speed control of I Induction motor using AC Voltage controller

Aim: To obtain the speed control and to calculate the output power of I Induction motor.

Apparatus :

Sno Equipment Quantity

1 I-Transformer 1

2 I-AC voltage controller power circuit with firing unit

1

3 I- Induction motor 1

4 Voltmeters(MI meters) 1

5 CRO with (1:10) Probe 1

6 Patch Chords As required

7 Tachometer 1

Circuit Diagram:


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Procedure :

Without load:

1. Make connections as per the circuit diagram. 2. Keeping the fairing angle pot at 180 degrees switch on the supply. 3. By varying firing angle pot note down the reading of voltmeter ammeter and speed of the

motor. 4. Plot the graph speed vs Firing angle.

With load:

1. Make connections as per the circuit diagram. 2. Keeping the fairing angle pot at 180 degrees switch on the supply. 3. By varying firing angle pot bring the motor to rated speed.

4. Put some load on the motor with the help of loading arrangement. 5. By decreasing the speed steps wise up to 90 degrees note down the readings of ammeter

voltmeter, speed and spring balances. 6. Plot the graph fairing angle vs Out put power.

Observation table:

Without load:

S.NO. Firing angle Volt meter reading Ammeter reading Speed.

With load:

S.NO. Firing angle

Volt meter reading

Ammeter reading

Speed. Load on motor

Torque Out put Efficiency

Documents

Power Electronics Lab Manual (2012-2013)