POWER ELECTRONICSAND SIMULATION LAB 3 rd YEAR-II SEMESTER

Transcription

1 POWER ELECTRONICSAND SIMULATION LAB 3 rd YEAR-II SEMESTER NAME OF THE STUDENT : REGISTERNUMBER : YEAR/ SEMESTER : STAFF INCHARGE : Mr. G.SRIDHAR BABU Assoc.Prof/EEE 1

2 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

3 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

4 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

5 TABLE OF CONTENTS Sl.No Experiment Name Experiment Date 1. Submission date Marks Signature SUBJECT INCHARGE INTERNAL MARK

6 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. Name of the Apparatus Range Type Quantity 1 1 AC voltage regulator power module Loading Rheostat 50, 2A Loading Inductor 150mH, 2A 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 TRIACs 10A, 600V, BT 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

7 1.5 MODEL GRAPH: Vi (v) Input Waveform 0 π 2π 3π 4π t (ms) Output Waveform Across R and RL- Load =0 0 V L (v) 0 t (ms) Output Waveform Across R- Load =90 0 V L (v) 0 t (ms) Output Waveform Across RL- Load =90 0 V L (v) 0 t (ms) 7

8 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: 1 sin 2 Output voltage, V 0 = V s 2 8

9 SINGLE PHASE AC VOLTAGE CONTROLLER WITH RL LOAD USING SCRS A 1 T 1 K 1 P 2 TYN616 G 1 1, 230V, 50Hz, AC 230V 0V 24V 24V 0V G 2 K 2 K1 G1 K2 G2 T 2 A 2 R L LOAD 50,2A N SINGLE PHASE AC VOLTAGE CONTROLLER WITH RL LOAD USING TRIAC TRIAC BT136 G P MT 1 MT 2 1, 230V, 50Hz, AC 230V 0V 24V 24V 0V G MT2 FIRING CIRCUIT R L LOAD 50,2A 0-250mH, 2A N 9

10 SINGLE PHASE AC VOLTAGE CONTROLLER WITH R LOAD USING SCRS A 1 T 1 K 1 P 2 TYN616 G 1 1, 230V, 50Hz, AC 230V 24V 0V G 2 K 2 K1 G1 K2 G2 T 2 A 2 R LOAD 50,2A 0V 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

11 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 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

12 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 circuit module and power circuit module 2 Loading Rheostat 50, 2A Loading Inductor 150mH, 2A 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 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

13 2.5 MODEL GRAPH: Voltage and Current waveforms in the Jones Chopper Ig1 t Ig2 t ISCR2 t VSCR2 t Vc t Ic t ISCR1 t ` VSCR1 t VL t 13

14 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 = T on /T 100 T= T on +T off 14

15 2.7CIRCUIT DIAGRAM: Circuit Diagram of DC Jones Chopper with RL Load 2.7.2Circuit Diagram of DC Jones Chopper with R Load T 1 DC Supply + T A R V To CRO D 1 L 1 L 2 15

16 2.8 TABULAR FORMS: At F 1 ( middle) S. Input Time in milli sec. Duty Output Theoretical No. voltage (V in ) T on (ms) T off (ms) cycle (%) voltage (V 0 ) value = T on /T At F 2 (maximum) S. Input Time in milli sec. Duty Output Theoretical No. voltage (V in ) Ton(ms) Toff(ms) cycle (%) voltage (V 0 ) value = T on /T RESULT: Thus the module and waveforms of a DC Jones chopper with R and RL loads was studied 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

17 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 firing module and power circuit module 2 Loading Rheostat 50, 2A Loading Inductor 150mH, 2A 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

18 3.5 MODEL GRAPH: TRIGGER OUTPUTS T 1 T 2 +V DC --V DC 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

19 3.7 CIRCUIT DIAGRAM Single Phase Parallel Inverter with R load D1 T1 RPS (0-30)V DC Supply + - L T2 D2 C 0V R - L o 50, 2A L Single Phase Parallel Inverter with RL load D1 T RPS + (0-30)V DC - Supply L T D2 C 0V RL L o a d 50, 150mH 2A 19

20 3.8 TABULAR FORMS: 3.8.1For R Load: S. Input Time in milli sec. Amplitude Output Theoretical No. voltage (V in ) T on (ms) T off (ms) in (V) V m average voltage output frequency (V 0 ) in Hz For R-L Load: S. Input Time in milli sec. Amplitude Output Theoretical No. voltage (V in ) T on (ms) T off (ms) in (V) average voltage output frequency V 1 V 2 (V 0 ) in Hz 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

21 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 converter power and firing module 2 Loading Rheostat 150, 5A Loading Inductor 150mH, 5A 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/TYN Diode : 25A, 1200V, BY126/BY 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

22 4.5 MODEL GRAPH: Vi (v) Input Waveform 0 π 2π 3π 4π t (ms) Output Waveform R and RL - Load at =0 0 V L (v) 0 t (ms) V L (v) Output Waveform R and RL -Load at = t (ms) V L (v) Output Waveform R and RL - Load at = t (ms) Output Waveform R and RL - Load at = t (ms) 22

23 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 0 0, 45 0, 90 0, and FORMULAE USED: Output voltage V 0 = V dc = Vm/ (1 + cos ) 23

24 4.7 CIRCUIT DIAGRAM: 4.7.1SINGLE PHASE HALF CONTROLLED CONVERTER WITH R LOAD 2 TYN616 P K1 G 1 K2 G 2 1, 230V, 50Hz, AC 230V 0V 30V 0V T1 D1 K 1 A 1 A2 K2 T2 D2 R LOAD 150, 5A N A1 A 2 2 1N SINGLE PHASE HALF CONTROLLED CONVERTER WITH RL LOAD 2 TYN616 P K1 G K2 1 G 2 1, 230V, 50Hz, AC 230V 0V 30V 0V T 1 K 1 A1 A 2 K2 T2 R L LOAD 150, 5A 0-150mH, 5A D 1 D 2 N A 1 2 1N4007 A 2 24

25 S. No. Input Firing Output voltage Output voltage angle (a) (V) Theoretical (V) voltage 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 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

26 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: F 1 = P 1 I g + P 2 I a = 50I g + 11I a 26

27 5.3 Circuit diagram of single phase full converter: 5.4Circuit file for Single phase full converter: VS 10 0 SIN ( V 60HZ) VG1 6 2 PULSE (0V 10V US 1NS 1NS 100US US) VG2 7 0 PULSE (0V 10V US 1NS 1NS 100US US) VG3 8 2 PULSE (0V 10V US 1NS 1NS 100US US) VG4 9 1 PULSE (0V 10V US 1NS 1NS 100US US) R L MH C UF RX VX 5 3 DC 10V VY 10 1 DC 0V * SUBCIRCUIT CALLS FOR THYRISTOR MODEL XT SCR XT SCR XT SCR XT SCR. SUBCKT SCR S SMOD RG VX 4 2 DC 0V 27

28 VY 5 2 DC 0V RT CT UF F1 2 6 POLY (2) VX VY 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

29 5.5 Circuit diagram of single phase Ac Voltage Controller: 5.6 Circuit file for Single phase ac voltage controller: VS 10 0 SIN ( V 60HZ) VG1 2 4 PULSE (0V 10V US 1NS 1NS 100US US) VG2 3 1 PULSE (0V 10V US 1NS 1NS 100US US) R L MH VX 6 0 DC 0V CS UF RS * SUBCIRCUIT CALLS FOR THYRISTOR MODEL XT SCR XT SCR. SUBCKT SCR S SMOD RG VX 4 2 DC 0V VY 5 2 DC 0V 29

30 RT CT UF F1 2 6 POLY (2) VX VY 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

31 Exp. No.:6 GATE FIRING CIRCUITS FOR SCRs Date: 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 UJT power module R load 50, 2A CRO & probe Dual Connecting wires - As required 6.3 SPECIFICATIONS: 1. SCRs : 400V, 4A, type 106 D 2. Diodes : 1N Diacs : D3202U 4. Zeners : 20V, 1W 5. UJTs : 2N 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

32 6.5 MODEL GRAPH: Vi (v) Input Waveform 0 π 2π 3π 4π t (ms) Output Waveform =0 0 V L (v) 0 V SCR (v) 0 t (ms) t (ms) V L (v) Output Waveform =90 0 V SCR (v) 0 0 t (ms) t (ms) 32

33 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 0 0, 45 0, 90 0, 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 0 0, 45 0, 90 0, and 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 0 0, 45 0, 90 0, and Bring the pot to the original position. 7. Switch OFF the power Supply. FORMULAE USED: Firing Angle = *10 3 * t (deg rees) 33

34 6.7 CIRCUIT DIAGRAM GATE FIRING CIRCUIT FOR SCR S-RESISTANCE FIRING CIRUCIT R LOAD 50, 2A 20V, 2A AC R R C T 1 TYN616 A D K R g K 1 1N TABULAR FORMS: A. i. Resistance Firing Circuit: - Sl. No. Resistance (R) in Ω Firing angle ( ) in s ii. Resistance Firing Circuit: - across SCR and Load Firing Sl. No. (R) in Ω angle ( ) in T on T off Amplitude s

35 GATE FIRING CIRCUIT FOR SCR S-RESISTANCE CAPACITANCE (RC) FIRING CIRUCIT R LOAD 50, 2A 20V, 2A AC R T 1 A 1 R C D 1 A D 2 K R g TYN616 K 1 G 1 C 4.7 F 1N4007 B. i. Resistance Capacitance Firing Circuit: - Sl. Resistance (R) Capacitance (c) Firing angle ( ) No. in Ω in Fd in s ii. Resistance Capacitance Firing Circuit: - Firing Sl. No. (R) in Ω angle ( ) in T on T off Amplitude s

36 C. i. UJT Firing Circuit: - GATE FIRING CIRCUIT FOR SCR S-UJT FIRING CIRUCIT R P 1, 230V, 50Hz AC 20V, 2A D 1 D 3 C 1000 F ZD K A R R C UJT 2N2646 T 1 A G K 50, 2A R L O A N D 4 D 2 C 4.7 F AC 20V, 2A S. Resistance (R) in No. Ω ii. UJT Firing Circuit: - Firing angle ( ) in s Pulse TFR 1:1:1 Firing Sl. No. (R) in Ω angle ( ) in T on T off Amplitude s

37 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 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

38 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 controlled converter power and firing module 2 Loading Rheostat 150, 5A Loading Inductor 150mH, 5A 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/TYN Diode : 25A, 1200V, BY126/BY 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

39 7.5 MODEL GRAPH: Vi (v) Input Waveform 0 π 2π 3π 4π t (ms) Output Waveform R- Load at =0 0 V L (v) 0 V L (v) 0 V L (v) 0 V L (v) 0 V L (v) 0 V L (v) 0 Output Waveform R- Load at =45 0 RL- Load at =45 0 R- Load at =90 0 RL- Load at =90 0 R- Load at =135 0 t (ms) t (ms) t (ms) t (ms) t (ms) t (ms) 39

40 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 0 0, 45 0, 90 0, and FORMULAE USED: Average output voltage R load, V Avg = Vm 1 cos 2Vm cos Average output voltage RL load, V Avg = 40

41 7.7CIRCUIT DIAGRAM : SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH R LOAD 4 TYN616 P K 1 G K 3 1 G 3 230V 30V T 1 T3 1, 230V, 50Hz, AC A 1 A 3 R LOAD 150, 5A 0V 0V K 4 G 4 G K 2 2 N T 4 T 2 A 4 A 2 7.8TABULAR FORMS: a. For R load S.No. Input voltage (V) Firing angle ( ) Output voltage (V) Theoretical Output voltage (V) 41

42 SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH RL LOAD 4 TYN616 P K 1 G K3 1 G 3 1, 230V, 50Hz, AC 230V 0V 30V 0V T 1 A 1 A 3 K 4 G 4 G 2 K 2 T3 R L LOAD 150, 5A 0-150mH, 5A N T 4 T 2 A 4 A 2 b. For RL load without freewheeling diode: S.No. Input voltage (V) Firing angle ( ) Output voltage (V) Theoretical Output voltage (V) 42

43 SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH FREEWHEELING DIODE FED RL LOAD 4 TYN616 P K 1 G K 3 1 G 3 1, 230V, 50Hz, AC 230V 0V 30V 0V T 1 A 1 A 3 K 4 G 4 G 2 K 2 T3 K A FD R L LOAD 150, 5A 0-150mH, 5A N T 4 T 2 A 4 A 2 c. For RL load with freewheeling diode: S.No. Input voltage (V) Firing angle ( ) Output voltage (V) Theoretical Output voltage (V) 7.9 MODEL CALCULATIONS: 43

44 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 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

45 Exp. No.:8 STUDY OF FORCED COMMUTATION CIRCUITS Date: 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

46 8.4 MODEL GRAPHS: CLASS-A COMMUTATION: CLASS-B COMMUTATION: CLASS-C COMMUTATION: CLASS-D COMMUTATION: 46

47 8.5 CIRCUIT DIAGRAM: CLASS-A COMMUTATION: CLASS-B COMMUTATION: T 1 L T L C (0-15V) C R To CRO (0-15V) R To CRO CLASS-C COMMUTATION: CLASS-D COMMUTATION: T 1 R 1 R2 (0-15V) C T 1 T 2 (0-30V) + TA R D L 47

48 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

49 8.7 TABULAR FORMS: S.No. Classes Time in milli sec. Amplitude in Volts T on (ms) T off (ms) V L V SCR Vc +V V A A S.No. Classes Time in milli sec. Amplitude in Volts B B B T on (ms) T off (ms) V L V SCR V C +V V +V V S.No. Classes Time in milli sec. Amplitude in Volts C C C T on (ms) T off (ms) V L V SCR V C V 1 V 2 +V V +V V S.No. Classes Time in milli sec. Amplitude in Volts D D D T on (ms) T off (ms) V L V SCR V C +V V +V V 49

50 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

51 Exp. No.:9 SINGLE PHASE CYCLO CONVERTER WITH R & RL LOADS Date: 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 EQUIPMENT Qty 1. I-φ Center tapped Transformer 1 2. I-φ Cyclo Converter power circuit with firing unit 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

52 9.4 MODEL GRAPHS: 1/2f cycloconverter waveforms 1/3f cyclo converter waveforms 1/4f cycloconverter waveforms 52

53 9.5 CIRCUIT DIAGRAMS: T 1 Ph 1-Φ, 230V 50Hz AC Supply T 3 R To CRO T 2 N center tapped transformer Fig1-Single phase cyclo converter with R-load T 4 T 1 Ph 1-Φ, 230V 50Hz AC Supply T 3 R To CRO T 2 L N center tapped transformer T 4 Fig2-Single phase cyclo converter with RL-load Fig-2 53

54 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

55 9.7 TABULAR FORMS: A) For R-Load: The input voltage V ph = V (As given by the instructor) Value of load resistance R L = Ω(As given by the instructor) Input frequency = Hz S.NO. Frequency division Firing angle(α) in degrees Time period in msec Frequency (practical) Frequency (theoretical) B) For RL-Load: The input voltage V ph = Value of load resistance R L = Value of Load inductance L= V (As given by the instructor) Ω(As given by the instructor) mh(as given by the instructor) S.NO. Frequency Firing angle(α) Time period in Frequency Frequency division 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

56 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 Resources: PSPICE Software 10.3CIRCUIT DIAGRAMS OF SINGLE PHASE INVERTER WITH PWM CONTROL (a) Circuit (b) PWM generator 56

57 (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 US US 1NS US) RR MEG VC PULSE (0-30V 0 1NS 1NS US US) RC MEG VC PULSE (0-30V US 1NS 1NS US US) RC MEG R L MH 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) Q QMOD Q QMOD Q QMOD Q QMOD.MODEL QMOD NPN(IS=6.734F BF=416.4 CJC=3.638P CJE=4.493P) RG RG RG RG * SUBCIRCUIT CALL FOR PWM CONTROL XPW PWM 57

58 XPW PWM XP PWM XP PWM * SUBCIRCUIT FOR PWM CONTROL.SUBCKT PWM R K R K RIN 5 0 2MEG RF K RO CO PF E E+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

59 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 R LE UH CE UF C UF L UH VX 4 5 DC 0V Q MODQ1.MODEL MODQ1NPN (IS=6.734F BF=416.4 ISE=6.734F BR= CJE=3.637P MJC= 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

60 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 LE UHCE UF IC=60V L UH R VX 5 0 DC 0V DM 0 3 DMOD.MODEL DMOD D (IS=2.2E-15 BV=1800V TT=0) Q 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

61 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

62 Exp. No.:12 Date: STUDY OF CHARACTERISTICS OF SCR, MOSFET & IGBT A. STUDY THE CHARACTERISTICS OF SCR OBJECTIVE: To plot the forward characteristics of SCR and the find the forward Resistance RESOURCES: S. No. Name of the Apparatus Range Type Quantity 1 SCR TYN 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 E 1 & E 2 (RPSU) at minimum position. 3. Set load potentiometer in minimum position. 4. Switch ON the supply and to set some value of V ak voltage (5V to 7V). 5. BY adjusting E 2 and set some value of I G (constant). 6. Slowly vary E 1 and note down the corresponding Vak and meter readings. 7. By varying E 2 (or) Gate current potentiometer R 2, adjust I G 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 V ak Vs I a. 11. Then from the forward characteristics take the slope and find out forward resistance by using the formulae V R f = I ak a ( ) 62

63 STUDY OF CHARACTERISTICS OF SCR (0-100mA)mc R + Ia - 1 = 1kΩ (0-25mA)mc R Ig G A TYN 616 K + Vak (0-5V)mc - V 2 RPS (0 30V) V 1 RPS (0 30V) 12.4TABULAR FORMS: I G1 = (ma) S.No. V AK (volts) I A (ma) I G2 = (ma) S.No. V AK (volts) I A (ma) 63

64 12.5 MODEL GRAPH: Ia (ma) I L I H I A2 I A1 I G I G I I G1 > O V AK1 V Ak2 V BO1 V BO2 V AK (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, R F = ( ) 64

65 B. TO STUDY THE CHARACTERISTICS OF MOSFET 12.7 OBJECTIVE: To plot the transfer characteristics and drain characteristics of MOSFET RESOURCES: S. No. Name of the Apparatus Range Type Quantity 1 MOSFET IRF 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 E 1 &E 2 (RPS) at minimum position initially. 3. Switch on the power supply. 4. Set E 1 to some voltage (constant) and note down the readings of I D AND Vgs in steps by adjusting E 2 in step of 0.5 volt. 5. Bring back E 1 & E 2 to minimum position and switch off the power supply. 6. Plot the graph V gs Vs I D. FORMULAE USED: Trans conductance (G M) = Change in Drain current / Change in Gate source voltage = ΔI D /ΔV GS 65

66 12.10TABULAR FORMS: Trans conductance characteristics: V DS = (V) S.No. I D (A) V GS (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 V GS by adjusting E Slowly vary E 1 and note down the readings of I D and V DS 5. Set some other values of V GS and repeat the procedure step Bring back E 1 and E 2 position in minimum and switch off the power supply. 7. Plot the graph I D Vs V DS FORMULAE USED: Drain Resistance (R D ) = ΔV DS /ΔI D 66

67 STUDY OF CHARACTERISTICS OF MOSFET (0-500mA)mc + Id - R 1 G A D S IRF Vds - (0-50V)mc V 2 RPS (0-30V) Vgs - (0-20V)mc + - V 1 RPS (0 30V) TABULATION: Drain characteristic:- V GS = (V) S.No. I D (A) V DS (V) 67

68 12.13 MODEL GRAPH: TRANS CONDUCTANCE CHARACTERISTICS ID ID (on) V DS = 15V V GS (Th) V GS (on) V DS 3.5V 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, G m = ( ), Drain Resistance R d = ( ) 68

69 C. STUDY CHARACTERISTICS OF IGBT 12.15OBJECTIVE: To obtain transfer and output characteristics of IGBT RESOURCES: S. No. Name of the Apparatus Range Type Quantity 1 IGBT IRGBC 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 PROCEDURE: Transfer characteristics: 1. Make connection as per the circuit diagram. 2. Set E 1 & E 2 (RPS) to minimum position Initially. 3. Switch ON the supply. 4. Set some value of V CE (constant) by adjusting E Vary E 2 in steps and note down the corresponding reading of V GE and I C. 6. Bring back E 1 & E 2 to original position and switch off the power supply. 7. Plot the graph V GE Vs I C. O/P or Collector characteristics: 1. Make the connections as per the circuit diagram. 2. Set some value of V GE (constant) and by adjusting E Slowly vary E 1 and note down the readings of V CE and I C values. 4. For some other value of V GE (constant), repeat the procedure step Bring back E 1 & E 2 to minimum position and switch off the power supply. 6. Plot the graph V CE Vs I C. 69

70 STUDY OF CHARACTERISTICS OF IGBT (0-500mA)mc + - Ic R 1 G IRBGC 20S C + Vce (0-50V)mc - E V 2 RPS (0 30V) Vge - (0-20V)mc + - V 1 RPS (0 30V) TABULAR FORMS:- a. Transfer characteristics: V CE = (V) S.No. V GE (V) I C (ma) 70

71 b. O / P or collector characteristics: V GE = (V) S.No. V CE (V) I C (ma) 12.19MODEL GRAPH: TRANSFER CHARACTERISTICS IC IC (on) V CE = 15V V CE (Th) V CE (on) V CE 5V COLLECTOR CHARACTERISTICS IC in V GE = 5.25V ma V GE = 5.2V V GE = 5.15V V GE = 5.1V V CE RESULT: Thus the characteristic of IGBT is studied and we plotted the Transfer and collector characteristics of IGBT. 71

72 Exp. No.:13 SINGLE PHASE SERIES INVERTER WITH R AND RL LOADS Date: 13.1 OBJECTIVE: To study the operation of Single-phase series inverter with R and RL loads and plot its output waveform 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 Regulated power supply (0 30 V) / 2 A 1 6 CRO 20 MHZ 1 7 Patch chords MODEL GRAPH (SERIES INVERTER): T 1 T 2 t ec 1 t ec 2 t t e o t 72

73 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 CIRCUIT DIAGRAM -SERIES INVERTER FUSE2A D 1 T 1 (0-30V), M.I V C 1 (0-30)V RPS L 1 L 2 LOAD CRO D 2 T 2 C 2 73

74 13.6 TABULAR FORMS (SERIES INVERTER): RESONANCE FREQUENCY = : FIRING ANGLE = S.No. Input Voltage Frequency Of Firing Output Voltage (V i ) Volts Circuit (Hz) V o (Volts) 13.7 RESULT: Thus a single-phase series inverter operation was studied and its output waveform was plotted 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

75 Exp. No.:14 Date: THREE PHASE HALF CONTROLLED BRIDGE CONVERTER WITH R LOADS OBJECTIVE The objective of Experiment is to analyze the operation (Switching) of three phase half controlled rectifiers with resistive load RESOURCES: S. No. Name of the Apparatus Range Type Quantity 1 3 Half controlled converter power and firing module 2 Loading Rheostat 150, 5A CRO & probe 20MHz Dual 1 5 Connecting wires - As required 14.3 SPECIFICATIONS: Input Supply : 415V / 3ph. Supply for phase synchronization and 230V, 50Hz Single phase supply for the power supply Output : Six pairs of pulse transformer isolated trigger pulses. Gate drive current : 230mA. Gate Voltage : Open circuit- 5.1V, SCR LOAD-1.2V. Gate pulse width : Fixed 6.3 msec. Firing angle control : Internal 180 to 0 phase control by Potentiometer External 180 to 0 phase control obtained by external control voltage between Vc and GND. Test points : 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 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