potti sriramulu chalavadi mallikarjuna rao. college … · 2018-11-13 · potti sriramulu chalavadi...

POTTI SRIRAMULU CHALAVADI MALLIKARJUNA RAO. COLLEGE OF ENGINEERING & TECHNOLOGY

(Affiliated to JNTU, Kakinada & Approved by AICTE New Delhi)

KOTTHA PETA, VIJAYAWADA - 520001.

Department of Electrical and Electronics Engineering

**********************************************************

MANUAL FOR

POWER ELECTRONICS LAB

III B.Tech II Semester (EEE)

2017-2018

Name: ……………………………………………………......

Roll Number: ……………………………………………....

PSCMR college of Engineering and Technology

ELECTRICAL AND ELECTRONICS ENGINEERING 1

Exp.No: Date:

STUDY OF CHARACTERISTICS OF SCR, MOSFET & IGBT

Aim:To study the characteristics of SCR, MOSFET & IGBT.

Apparatus: 1. Characteristics of SCR, MOSFET and IGBT study unit. 2. Ammeters - (0-500) mA, MC-1 No, (0-25) mA, MC-1 No. 3. Voltmeters - (0-50) V, MC-1 No, (0-30) V, MC-1 No

4. CRO 5. Connecting wires

a) Circuit Diagram of SCR:

b) Expected Graph



Procedure:

1. Connections are made as per the circuit diagram. 2. Now switch ON the main supply and initially keep V1& V2 at minimum and also set

load potentiometer R1 in the minimum position. 3. By adjusting the Potentiometer R2, the gate current is maintained constant. 4. By adjusting R1, the anode voltage VAK and anode current Ia are noted. 5. This procedure is repeated for different gate currents.

6. The noted values are tabulated and graph is drawn between anode current and anode

cathode voltage.

Tabular Form:

Result:

S.NO Ig1= (mA) Ig2= (mA)

VAK(V) IA(mA) VAK(V) IA(mA)



b) Characteristics of MOSFET

Circuit Diagram:

Expected Graph:

Transfer Characteristics Drain Characteristics



Procedure:

For Transfer Characteristics:

1. Connections are made as per the circuit diagram.

2. Initially keep V1& V2 are zero.

3. VDS is kept constant say 10V by varying Drain resistance R1.

4. Slowly vary V2 and note down ID and VGS readings for every 0.5V.

5. This procedure is repeated for different drain source voltages VDS.

6. Graph is drawn between ID v/s VGS at different values of drain source voltages VDS.

For Drain Characteristics:


2. VGS is kept constant at a fixed value say 3.5V by varying the Gate supply V2.

3. Slowly vary V1 and note down the values of ID &VDS.

4. This procedure is repeated for different gate source voltages VGS.

5. Graph is drawn between ID& VDS at different values of gate source voltages VGS.

Tabular Form:

For transfer Characteristics:

S.NO VGS1= (Volts) VGS1= (Volts)

VDS(V) ID(mA) VDS(V) ID(mA)



For Drain Characteristics:

Result:

S.NO VDS= (Volts)

VGS(V) ID(mA)



C) Characteristics of IGBT Circuit diagram:

Expected Graph:

Transfer Characteristics Collector Characteristics

Procedure:

For Transfer Characteristics:


2. Initially keep V1& V2 are zero.

3. VCE is kept constant say 10V by varying Drain resistance R1.

4. Slowly vary V2 and note down IC and VGE readings for every 0.5V.

5. This procedure is repeated for different collector emitter voltages VCE.

6. Graph is drawn between IE& VGE at different values of collector emitter voltages VCE.



For Collector Characteristics:


2. VGE is kept constant at a fixed value say 5V by varying the Gate supply V2.

3. Slowly vary V1 and note down the values of IC& VCE.

4. This procedure is repeated for different gate emitter voltages VGE.

5. Graph is drawn between IC& VCE at different values of gate emitter voltages VGE.

Precautions:

1. Check the all components before making connections.

2. Keep all knobs at minimum position before you switch ON the supply.

3. Working conditions of all the equipment’s must be checked properly.

4. Check the fuses and terminals.

Tabular Form: For transfer Characteristics:

S.NO VCE= (Volts)

VGE(V) IC(mA)



For Collector Characteristics:

Result:

S.NO VGE= (Volts) VGE= (Volts)

VCE(V) IE(mA) VCE(V) IE(mA)



Exp.No: Date:

GATE FIRING CIRCUITS FOR SCR (R, RC, UJT) Aim:

To trigger an SCR by using R, RC & UJT triggering circuits and observe the output

waveforms for different firing angles.

Apparatus: -

S.No Apparatus Quantity

1 Triggering circuit Kit 1

2 Unearthed C.R.O 1

3 Connecting probes 1

Procedure:

Resistance firing circuit:

(1) Apply 12V of AC input to the anode and cathode of SCR terminals from a step down

transformer. (2) Connect the anode, cathode & gate terminals of SCR to the corresponding A, K, G

terminals in the R – Triggering circuit. (3) Connect the load of 50Ω/2A between the load terminals.

(4) Observe the variations in the voltage across the load for different firing angles (by Varying potentiometer) with the help of CRO, plot waveforms of firing signals & output

voltage for firing angle 450, 90

0.

RC firing circuits:

1. Apply 12V of AC input to the anode and cathode of SCR terminals from a step down

transformer. 2. Connect the anode, cathode & gate terminals of SCR to the corresponding A, K, G

terminals in the R – Triggering circuit. 3. Connect the load of 50Ω/2A between the load terminals.

4. Observe the variations in the voltage across the load for different firing angles (by Varying potentiometer) with the help of CRO, plot waveforms of firing signals & output

voltage for firing angle 450, 180

0.



UJT firing circuit:

1. Apply 12V of AC input to the anode and cathode of SCR terminals from a step down

transformer. 2. The rectified output is applied to the UJT terminals through the résistance as shown in

the circuit diagram. 3. Connect the cathode & gate terminals of SCR to the corresponding K, G terminals in

the UJT – Triggering circuit. 4. Connect the load of 50Ω/2A between the load terminals.

5. Switch ON the supply for UJT Triggering circuit.

6. Observe the variations in the voltage across the load for different firing angles (by varying potentiometer) with the help of CRO, plot waveforms of firing signals &

output voltage for firing angle 450, 180

0.

Precautions:

(1) Initially the potentiometer should be in minimum resistance position.

(2) Vary the Potentiometer gradually.

(3) Observe the output waveforms carefully on the CRO



Circuit Diagram:

Circuit Diagram to obtain Resistance Triggering

Model Graphs:



Circuit Diagram:

Circuit Diagram to obtain RC Triggering

Model Graphs:



Circuit Diagram:

Circuit Diagram to obtain UJT Triggering

Model Graphs:



Result:



Exp.No: Date:

SINGLE PHASE HALF CONTROLLED BRIDGE CONVERTER

Aim:

To Study and observe the working and operation of a 1 half controlled bridge converter

with R and RL loads & to plot the waveforms across the load and SCR for different firing angles.

Apparatus:

S.No. Apparatus Range Type Quantity

1. Single Phase isolation

transformer

230/115-60-30-0-30-

60115V

1 KVA

Shell type 1

2. SCRs 12A /600 V TYN612 2

3. Power Diodes --- --- 2

4. Load Rheostat 145 / 2.8A Wire wound 1

5. Inductive Load (0-25-50-100-

150mH),2A

…. 1

6. Voltmeter 0-30 V MC 1

7. Ammeter 0-2A MC 1

8. 1 half controlled rectifier

bridge firing Kit

…. …. 1

9. Cathode Ray oscilloscope …. …. 1

10. CRO Probe …. ….. 1

11. Connecting wires …. …. Required

No

Procedure:


2. Firing pulses are applied for the respective SCR’s from the firing circuit.

3. The main supply is switched ON and triggering circuit is switched ON.

4. Wave forms across the load are observed in CRO.

5. Values are tabulated for different firing angles.

6. The output wave forms are plotted on the graph sheet.

7. Switch off the supply.

8. Repeat the above procedure for RL Load.

Precautions:

1. Initially, keep MCB in ON position.

2. Don’t use CRO in dual trace mode.

3. Use fixed terminals of load rheostat.



CIRCUIT DIAGRAM FOR 1-PHASE HALF CONTROLLED BRIDGE RECTIFIER WITH

R LOAD:

CIRCUIT DIAGRAM FOR 1-PHASE HALF CONTROLLED BRIDGE RECTIFIER WITH

R L LOAD:

TRIGGERING CIRCUIT FOR 1-PHASE HALF CONTROLLED BRIDGE RECTIFIER:



Waveforms for R-Load:

Single phase HCBR circuit and waveforms for RL-Load:

(a) Circuit diagram for 1-phase half controlled bridge rectifier with RL load

(b) Waveforms of RL load



Expressionsfor Output Voltages:

R-Load:

0( )

1sin 1 cosm

mavg

VV V d

` = 1 cosmV

RL-Load:

0

1sin cos cosm

mavg

VV V d

Tabular Form:

Load Firing angle

(degrees)

Voltage across load, Vdc

(Volts)

Load Current

Idc

Theoretical Practical Theoretical Practical

R- load

RL – load



Result:



Exp. No: Date:

SINGLE PHASE FULLY CONTROLLED BRIDGE CONVERTER

WITH R AND RL LOAD

Aim:

To Study and observe the working and operation of single phase fully controlled bridge

converter with R and R-L Loads and to plot the voltage waveforms across load and thyristors (with

and without freewheeling diode) for different firing angles.

Apparatus:

S. No Apparatus Range Type Quantity

1. Isolation transformer 1 KVA, 230V/ 115-

60-30-0-30-60-115 V

Shell 1

2. CathodeRay Oscilloscope … … 1

3. Load Rheostat 100 ohms/1A Wire

wound

1

4. Inductive Load with

tapping’s

0-50-100mH, ….. 1

5. Silicon Controlled

Rectifiers

12A/600 V TYN612 4

6. 1 fully controlled

bridge converter firing

Kit

….. ….. 1

7. Voltmeter (0-30V) MC 1

8. Ammeter (0-2A) MC 1

9. CRO Probe …. …. 1

10. MCB 230V/6A …. 1

11. Fuse 5A Glass 1

12. Connecting wires … … Required

No



CIRCUIT DIAGRAM FOR 1-PHASE FULLY CONTROLLED BRIDGE CONVERTER

WITH R LOAD:

CIRCUIT DIAGRAM FOR 1-PHASE FULLY CONTROLLED BRIDGE CONVERTER

WITH R-L LOAD:

TRIGGERING CIRCUIT FOR 1-PHASE FULLY CONTROLLED BRIDGE CONVERTER:



Procedure:

1. Observe the trigger outputs using CRO.

2. Disconnect the supply as they are proper.

3. Connect the circuit as per circuit diagram and switched ON the supply.

4. Supply the trigger pulses to the respective SCR’s

5. Note the load voltage and load current for different firing angles.

6. Repeat the above procedure for R-L load with and without freewheeling diode.

7. Plot the output waveforms on a graph sheet.

8. Disconnect the supply.

Precautions:

1. Use the fixed terminals of load rheostat.

2. Don’t connect CRO in dual trace mode.

3. Initially keep MCB in ON position.

4. The Power circuit and input must be electrically isolated.

5. Carefully observe waveforms on CRO.

Waveforms ForR-Load:

Waveforms for RL-Load:



Expressions For Load Voltage And Load Current:

With R – load:

Average load voltage, 1

sindc mV V t d t

cosmVt

1 cosmV

Load current, 1 cosdc mdc

V VI

R R

With R-L Load With continuous mode:

With R-L Load With discontinuous mode:

Average load voltage, 1

sindc mV V t d t

1 cosmVt

cos cosmV

Load current, cos cosdc mdc

V VI

R R

With R-L Load and with freewheeling diode:

Average load Voltage, 1

sindc mV V t d t

= cosmVt

= 1 cosmV

Load current, dcdc

VI

R

= 1 cosmV

R



Tabular Form:

Load Firing angle

(degrees)

Voltage across load, Vdc

(Volts)

Load Current

Idc


R- load

RL – load

RL Load

With

freewheeling

diode



Result:



Exp. No: Date:

SINGLE PHASE AC VOLTAGE CONTROLLER WITH R AND R-L

LOAD

Aim:

To Study the working of 1 AC voltage controller with R and RL Loads and to observe

and plot the voltage waveforms across load and SCR for different firing angles.

Apparatus:


1. Ammeter (0-1A) MI 1

2. Voltmeter (0-35 V) MI 1

3. CRO …. …. 1

4. Load Rheostat 50 /5A Wire wound 1

5. Inductive Load 0-150 mH/2A …. 1

6. SCRs 12 A/600 V TYN 612 2

7. 1 center tap transformer 100VA, 230/24-0-

24V

Shell type 1

8. 1 A.C. voltage controller

firing circuit

…. …. 1

9. CRO Probe ….. …. 1

10 Connecting wires ….. ….. Required

No.

Procedure:

1. Switch ON the power supply.

2. Observe the trigger outputs of the firing circuit for different firing angles using CRO.

3. Make the connections as per the circuit diagram.

4. Switch ON the triggering pulses to respective SCRs in the power circuit.

5. Plot the output voltage waveforms across the load and SCRs for different firing angles.

6. Repeat the above procedure for R-L load (with firing angle being greater than power factor) and

draw the output waveforms.

7. Disconnect the supply.

Precautions:

1. CRO should not be used in dual trace mode.

2. Use fixed terminals of load rheostat.

3. An isolation transformer should be placed between power circuit and input.



CIRCUIT DIAGRAM FOR 1-PHASE A.C. VOLTAGE CONTROLLER

WITH R-LOAD:

CIRCUIT DIAGRAM FOR 1-PHASE A.C. VOLTAGE CONTROLLER

WITH RL-LOAD:

TRIGGERING CIRCUIT FOR 1-PHASE A.C. VOLTAGE CONTROLLER:



Waveforms for R-Load:

Waveforms for RL-Load:



Theoretical Calculations:

Tabular Form:

Firing angle

(degrees) Voltage across load, 0 rms

V

(Volts)

Load Current

Irms

(Amps)

R- load

RL – load



Result:



Exp.No: Date:

SINGLE PHASE STEP DOWN CYCLOCONVERTER WITH R AND

R-L LOADS

Aim:

To Study and observe the operation of 1- Step down cycloconverter with R and RL loads

and to plot the voltage waveforms across the load and SCRs for different firing angles.

Apparatus:


1. SCRs 12A/ 600V TYN612 4

2. 1- Center taped step-down

transformer

230/9-0-9v,1A,18VA ---- 1

3. Load Rheostat 145 / 2.8A Wire Wound 1

4. Inductive load (0-150mH), 2A ….. 1

5. Cathode Ray Oscilloscope,

CRO Probe

…. …. 1

6. 1 Step down cyclo converter

Triggering Circuit Kit

…. ….. 1

7. Voltmeter (0-30V) MI 1

8. Ammeter (0-200mA) MI 1

9. Main Circuit Breaker 230V/6A … 1

10. Connecting Wires ….. …. Required

no.

Procedure:

1. Switch on the main supply to the firing circuit.

2. Observe the test points and trigger outputs by changing frequency division and by varying firing

angle, using CRO.

3. Switch OFF the supply to the firing circuit.

4. Make the power circuit connections as per the circuit diagram.

5. Connect the firing pulses from the firing circuit to the respective SCRs in the power circuit.

6. Switch ON the circuit breaker.

7. Switch ON the supply to firing circuit and the main supply.

8. Set the frequency division to ‘3’.

9. Vary the firing angle potentiometer and observe the waveforms across the load and note down

the readings of voltmeter and ammeter.

10. Repeat the experiment for different firing angles.

11. Switch OFF the supply to the firing circuit and main supply.



CIRCUIT DIAGRAM FOR 1-PHASE STEPDOWN CYCLO CONVERTER:

TRIGGERING CIRCUIT FOR 1-PHASE STEPDOWN CYCLO CONVERTER:



Precautions:

1. As the output is zero even after all the connections made properly, MCB is switched off and

A.C. input connections to the power circuit are interchanged. This is done to synchronize

firing circuit and power circuit.

2. The frequency division is changed only when the trigger pulse switch is at OFF position.

3. Load Rheostat is connected in the circuit with its fixed terminals only.

4. CRO is not used in dual trace mode.

Waveforms:

Theoretical Calculations:



RL Load:

Output Voltage,

1

2 2 2

0m

rms

V SinV d

1

22 2

2 22

mV Sin Sin

Tabular Form:

Voltage across the load

0 ( )V volt

Load current

Io(Amps)


R-Load

R-L Load



Result:



Exp. No: Date:

THREE -PHASE HALF CONTROLLED BRIDGE CONVERTER

WITH R & RL LOAD Aim:

The aim of Experiment is to analyze the operation (Switching) of three phase halfcontrolled converter with resistive and inductive load using VPET-218 module.

Apparatus:

Procedure: Connection procedure:

1. Connect the module to single phase ac supply through power chords. 2. Connect the three phase ac input to the connection provide on the module. 3. Connect the three phase ac input to R, Y, B, N terminal of the PI connector for trigger pulse

generators. 4. Connect the trigger pulse output from isolation transformer to the SCR gate cathode using

pulse patch cards. 5. Connect the external RL load across input terminals of the module.

6. Connect the CRO across the load.

Experimental procedure:

1. Switch ON the power supply to the module.

2. Switch ON the pulse ON/OFF switch SW and check waveforms at various test points.

3. Vary the firing angle step by step in range (0-120)

4. For each vary the firing angle observe the output waveform though the CRO. 5. The output voltage calculated from the above given formula and measured values are

tabulated as shown. 6. The various waveforms are plotted on the graph.

Service tip: 1. Verify firing circuit waveforms at least point with respect to ground.

2. If all test point waveforms are not available much output power supply regulator. 3. Check whether 24V ac input it is not 24V step down transformer may fault.

S.NO Apparatus Quantity

1 VPET Module 1

2 Pulse Patch

Chords

As per Required

3 R-Load 1

4 RL-Load 1

5 CRO 1



Circuit diagram:

Model Graph:



Tabular Form:

S.No Firing Measured Output Calculated

Angle Voltage Output

Voltage

Result:



Exp. No: Date:

SINGLE PHASE INVERTER WITH PWM CONTROL.

Aim:Study of single phase PWM Inverter firing circuit Apparatus Required:

S.No

Apparatus

Quantity

1

PWM Inverter Kit

1

2

CRO

1

3

Patch Chords

As per

Required 4

RL-Load

1

Procedure:

1. Make the connection as per the circuit diagram.

2. Connect the gating signal from the inverter module.

3. Switch ON D.C 24 V.

4. Keep the frequency knob to particulars frequency.

5. Observe the rectangular and triangular carrier waveforms on the CRO.

6. Obtain the output waveform across the load Rheostat. Precautions:

1. The voltage applied should not exceed in the ratings of the diode

2. The diodes will be connected correctly



Circuit Diagram:

Model Graph:



Result:



Exp. No: Date:

SINGLE -PHASE DIODE BRIDGE RECTIFIER WITH R LOAD

AND CAPACITANCE FILTER. AIM: - To calculate the ripple factor of a bridge rectifier, with and without filters. APPARATUS:-

S.No Apparatus Quantity

1 Experimental Board 1

2 Diodes, IN4007 4

3 Resistor, 1KΩ 1

4 Capacitor, , 100μF/25v 1

5 Transformer, (12-0-12v) 1

6 MultiMate’s 2

7 Connecting Wires As per Required

Procedure:- 1. Connections are made as per the circuit diagram. 2. Connect the ac main to the primary side of the transformer and secondary side to the bridge

rectifier. 3. Measure the ac voltage at the input of the rectifier using the multi meter. 4. Measure both the ac and dc voltages at the output of the Bridge rectifier. 5. Find the theoretical value of dc voltage by using the formula.

Precautions:- 1. The voltage applied should not exceed in the ratings of the diode 2. The diodes will be connected correctly



Circuit Diagram:

Without filter:

With filter:

Model Graph:



Calculations: Theoretical calculations:

Vrms = Vm/ √2

Vm =Vrms√2

Vdc=2Vm/П (i)Without filter:

Ripple factor, r = √ ( Vrms/ Vdc )2 -1 = 0.482 (ii)With filter:

Ripple factor, r = 1/ (4√3 f C RL) where f =50Hz

C =100µF RL=1KΩ

Practical Calculations:

Without filter:

Vac=

Vdc=

Ripple factor, r=Vac/Vdc

With filter:-

Vac=

Vdc=

Ripple factor,r=Vac/Vdc

Observations: Without Filter:

Vm Vac Vdc Ripple factor

Without filter:

V1 V2 Vm Vac Vdc Ripple factor



Result:



Exp.No: Date:

Forced Commutation Circuits

Aim: To study the forced commutation circuits of Class A, Class B, Class C, Class D & Class D.

Apparatus: 1. Forced Commutation Study Module

2. Rheostat-50Ω/1A, 360Ω/1.2A.

3. Loading Inductor

4. CRO

5. Connecting wires-As per Required

Circuit Diagram:

For Class A Commutation: Waveforms:

Procedure:


2. Connect trigger output to gate and cathode of SCR.

3. Switch ON the supply to power circuit and observe the voltage waveforms across Load,

Thyristor and capacitor by varying the frequency potentiometer.

4. Repeat the above procedure for different values of R, L & C.

5. The output waveforms are plotted on graph sheet.



For Class B Commutation: Waveforms:

Procedure:



3. Switch ON the supply to power circuit and observe the voltage waveforms across

Load, Thyristor and capacitor by varying the frequency potentiometer.

4. Repeat the above procedure for different values of R, L & C.


For Class C Commutation: Waveforms:



Procedure:


2. Connect T1 and T2 gate pulse from the firing circuit to gate and cathode of thyristors

T1 and T2 and observe the waveforms across R1 and R2 by varying the duty cycle.


For Class D Commutation: Waveforms:

Procedure:


2. Connect T1 and T2 gate pulse from firing circuit to corresponding SCR in power circuit.

3. Initially keep trigger circuit at OFF position to charge the capacitor. This can be

observed by connecting CRO to the capacitor.

4. Now trigger circuit is kept ON position and note down the voltage waveform at different

duty cycles.




For Class E Commutation: Waveforms:

Procedure:



3. Switch ON the supply to power circuit and observe the voltage waveforms across

Load, thyristors.


Precautions:

1. Before making the connection, check the components.

2. Keep the knobs in minimum position.

3. Working conditions of all the equipment’s must be checked properly.

4. Check the fuses and terminals.



Result:

potti sriramulu chalavadi mallikarjuna rao. college … · 2018-11-13 · potti sriramulu chalavadi...

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