Transcript
BITS-PILANI, K.K BIRLA GOA CAMPUS
Laboratory Manual EEE/INSTR F342 Power Electronics Semester II 2016-2017
Team of Instructors Femi R, Dr. Narayan Manjarekar, Dr. Gautam Gautam Bacher, Dr. Shashidhara Mecha Kotian, Metilda Sagaya Mary N. J., Athokpam Bharatbushan Singh, Prakash Lamani, Ishwar R Rathod
List of experiments 1. Preparatory Laboratory Experiment- Introduction to Isolated and high voltage measurement: measurement: Uncontrolled bridge rectifier and controlled half bridge Rectifier 2. Study of Step down converter 3. Study of Boost converter 4. Study of Forward converter 5. Study of Single Phase Semi-controlled and fully Controlled Rectifier. 6. Study of Three Phase Semi controlled rectifier. 7.
Study of Single phase AC/AC converters.
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List of experiments 1. Preparatory Laboratory Experiment- Introduction to Isolated and high voltage measurement: measurement: Uncontrolled bridge rectifier and controlled half bridge Rectifier 2. Study of Step down converter 3. Study of Boost converter 4. Study of Forward converter 5. Study of Single Phase Semi-controlled and fully Controlled Rectifier. 6. Study of Three Phase Semi controlled rectifier. 7.
Study of Single phase AC/AC converters.
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SOME PRECAUTIONS AND SAFETY MEASURES
1. All students should wear full shoes with rubber sole. Loose clothes or loose hair is to be avoided. 2. Do not touch any live terminals or wires. For changing any connections you must switch-off the supply. 3. Beware of the dynamic machinery and consciously keep a distance. 4. Before switching ON the supplies, get your circuit connections approved by the instructors. 5. Be alert and always power OFF if you want to make any change in connections. 6. Make sure you switch OFF the measuring instruments once you are done with the experiment.
INSTRUCTIONS REGARDING OPERATION OF LAB
1. 2.
Thoroughly read the instruction set and come prepared to conduct the experiment. Before starting the experiment: (a) Come with m a n u a l w i t h the the relevant e x p e r i m e n t . (b) Note down the safe safe operating limits of the the converter. Never exceed exceed the ratings specified. (c) Write
down
the
instruments
and
accessories
that
you
need
to
conduct
the
experiment (along with their ranges, rating etc.). 3. Connect the wires, multimeters, multimeters, scope etc. as per the the circuit diagram. Get the the circuit connections verified by the instructor. 4. Start/switch-on the set (instructions are given in the instruction set). 5. Carry out the experiment experiment as per the steps given in instruction set. Record the readings/ note the waveforms. 6.
All comput computat ations ions are to be carried carried out in the laborato laboratory ry itself. itself. Attach Attach g r a p h s h e e t a n d a ny additional sheet you need.
7. You are required to submit the completed lab report of the experiment of the previous turn when you enter the laboratory.
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Tips for safety and accuracy for measurements in Power Electronic Laboratory 1. Individual measurements has to be done in isolation in Power electronic systems as the reference (ground ) for most of the measurements will be at different potentials.
Make sure that the
oscilloscope that is used for the measurement has isolated channels for measurement. If not, please use the Power isolation section provided in the kit. Failure to use proper isolation may lead to damage to the equipment and also may result in injury to the user(s). 2. Take the appropriate probe rating/ attenuation to make sure that you operate safely and obtain accurate results. For higher voltages (greater than 100V), it is suggested to use a probe/ isolation section of 100x. For grid voltage levels, 100x must be used. 3.
Always make sure that you switch OFF the power supply for making any change in connection or even for changing a measurement point. If not, you may open circuit an inductor or short circuit a capacitor inadvertently which may lead to serious damage of equipments and may result in injuries to the user(s).
4. Take note of the attenuation factor in case of probes used and/or if you are using power isolation section, (e.g:- 1x, 10x , 100x, 10mV/A) to get the scaling factor of the measured value. This information may be used as setting for the Digital storage oscilloscope to make sure that the measurement displayed is scaled appropriately. In case you are not using the setup option in DSO, take care of the scaling in your calculations. 5.
If sensing resistances are used for measuring currents, please use the appropriate scaling factor to get the reading. For example, if Rsense=0.1Ω, then the scaling factor is 100mV/ A or 10A/V.
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1. PREPARATORY LABORATORY EXPERIMENT
INTRODUCTION TO ISOLATED AND HIGH VOLTAGE MEASUREMENT Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To Study the isolated high voltage measurement and current measurement using CRO/DSO and multimeter for a single phase uncontrolled bridge rectifier.
b.
To study the firing pulse generation circuit.
c.
To study the measurement of firing angle and functioning of a single phase half wave controlled (single thyristor switch) rectifier.
EQUIPMENTS NEEDED 1.
Cathod Ray Oscilloscope/Digital Storage Oscilloscope.
2.
Voltage probes and clamp-on current probes (Tektronix A621).
3.
Digital Multimeter
4.
ST2700 High Voltage Power Electronics Lab
5.
Patch Cords & Operating manual for HV lab 2700.
PRECAUTIONS: Make sure that for all the measurements above 50V, power isolation section (Powerscope) provided on the setup is to be used. Attenuation for the power isolation unit should be kept at 100x for voltages higher than 100V. Make sure that Ammeters are connected in series with and Voltmeters are connected parallel across the load respectively. Make sure use appropriate range in case of voltmeter/ammeter are within the proper range. Verify the type (AC/DC) before connection. Clamp-on Current probe is to be directly connected to CRO.
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CONNECTION DIAGRAM:
Figure 1.1 : Single Phase Bridge Uncontrolled Rectifier
I.
PROCEDURE FOR STUDYING THE ISOLATED HIGH VOLTAGE MEASUREMENT AND CURRENT FOR A SINGLE PHASE BRIDGE UNCONTROLLED RECTIFIER:
Make sure that there is no connection on the board initially. 1.
Make Connections according to Figure (a).
2.
Connect Line Terminal (L) from single phase supply to anode of diode D1 or cathode of diode D4 and connect neutral (N) terminal from single phase supply to anode of diode D2 or cathode of diode D3.
3.
Connect one terminal of load from Load Assembly to common cathode terminal of diode D1 and diode D3 and other terminal of load is connected to common anode terminal of diodes D4 and D3.
4.
Connect the voltages to be measured (voltage across the load and voltage across diode D1), from the power circuit to the input of the power scope using patch chords.
5. Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A. Similarly, Connect BNC
to BNC cable at CH2 of oscilloscope to output of Power Scope B. 6. Switch ATT of A is at ‘x 100’ position and switch of coupling of A should be at ‘DC’ position. 7.
Connect input of Power Scope A to the load.
8.
Connect the Lamp at the Load.
9.
Connect the DC Voltmeter, Ammeter at the load.
10. Verify the connections before turning the MCB of single phase supply ON. 11. Switch on MCB of Single Phase Supply and observe the voltage waveforms on the oscilloscope. 12. Now remove the output voltage from channel 1, and connect the clamp-on current probe (directly) to channel 1 of the oscilloscope and measure the diode voltage (VD1)
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and
diode
current
(ID1) simultaneously.
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13. Repeat the measurements and observe the waveforms of load voltage (VL) vs load current (IL), input voltage (VS) vs input current (I S) using oscilloscope. Also make the DC voltage measurements us in g multimeter. 14. Take the readings and tabulate in Observation Table (a). Model Waveforms
OBSERVATION TABLE 1.1: Vs= Specification of a single lamp = Resistance of a single lamp = RLOAD=
V,
W
Ω
Ω
Measured Output Voltage (Vo)
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Calculated Output Voltage (Vo)
Measured Output Current (Io (DC))
Input current, (IS (RMS))
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Figure 1.2: Ramp comparator firing circuit II.
PROCEDURE FOR STUDYING THE ISOLATED MEASUREMENT AND RAMP FIRING SCHEME FOR SINGLE PHASE RECTIFIERS:
Make sure that there is no connection on the Work Bench initially. 1.
Switch on the three phase MCB of back panel. Red, Yellow and Blue indicator glow at front panel.
2.
Connect +12V, +5V and ground (GND) and connect 18-0-18 at ramp comparator firing circuit from single phase low voltage power supply.
3.
Switch on the oscilloscope. Connect BNC to Test Probe cable at CH1 and CH2 of oscilloscope.
4.
Observe the output of the zero crossing detector 1 with respect to ground in CH1 and the output of zero crossing detector 2 with respect to ground n CH2. Note that, the signals may be connected without isolation. Observe the phase shift between the two signals.
5.
Observe the output of ramp generator at point 3 with respect to in CH1.
6.
Observe the reference voltage at point Vref with respect to ground. Vary the firing angle control potentiometer and observe the variation in Vref.
7.
Observe the output of ramp comparator and pulse generator at point 4 with respect to ground in CH1 and output at point to with reference to ground at point 5 in CH2. Vary the firing angle control potentiometer and observe the pulse width variation in pulse 1.
8.
Connect patch cord point 4 to point 6 and connect patch cord point 5 to point 7.
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9.
Observe the gate pulse at G1 with respect to K1 (OR G2 with respect to K2) vary the firing angle control potentiometer and observe the variation in gate pulse in CH1. Do not connect two signals simultaneously.
10. Observe the input voltage, gate pulse at G1 with respect to K1, and G3 with respect to K3 using the isolated channel DSO (TPS 2014B). Note that you may connect the two outputs simultaneously to two/four
channels of the DSO. Vary the firing angle control potentiometer and observe the variation in gate pulse. ------------------------------------------------------------------------------------------------------------------------------------
Figure 1.3: Single phase half wave controlled rectifier. III.
PROCEDURE FOR STUDYING THE ISOLATED HIGH VOLTAGE MEASUREMENT AND CURRENT FOR A SINGLE PHASE BRIDGE UNCONTROLLED RECTIFIER:
Make sure that there is no connection on the Work Bench initially. 1.
Switch on the three phase MCB of back panel. Red, Yellow and Blue indicator glow at front panel.
2.
Connect +12V, +5V and ground (GND) and connect 18-0-18 at ramp comparator firing circuit from single phase low voltage power supply.
3.
Use SCR1 from SCR Assembly and to construct single phase half wave controlled rectifier configuration.
4.
Connect Line Terminal (L) from single phase supply to anode of SCR1.
5.
Connect the one terminal of load from Load Assembly to cathode terminal of SCR1 and other terminal of load is connect to neutral terminal from single phase supply.
6.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from ramp comparator firing circuit.
7.
Verify the connections before switch on the MCB of single phase supply.
8.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A.
9.
Switch ATT of A is at ‘x 100 ’ position and switch of coupling of A should be at ‘DC’ position.
10. Connect input of Power Scope A to the load. 11. Connect the Lamp at the Load.
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12. Switch on MCB of Single Phase Supply and observe the output waveform of load terminals on the oscilloscope. 13. Connect the DC Voltmeter at the load and measure the output DC voltage across the load. 14. Observe the voltage waveform at the load.
MODEL WAVEFORM
Measured Output Voltage (Vo)
Calculated Output Voltage (Vo)
Measured Output Current (Io (DC))
Input current, (IS (RMS))
GRAPHS 1. Draw the graphs of Line Voltage (VS), Output Voltage (Vo), Supply Current (IS), Diode voltage (VD1) and Diode Current (ID1) for Single Phase Bridge Uncontrolled Rectifier. 2. Draw the graphs of Line Voltage (VS), Output Voltage (Vo), Supply Current (IS), Diode voltage (VD1) and Diode Current (ID1) for Single Phase half wave controlled rectifier.
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SPECIFICATION FOR THE ST2700 HIGH VOLTAGE POWER ELECTRONICS LAB
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EXPERIMENT No. 2
STUDY OF STEP DOWN CONVERTER Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To Study the PWM generation Circuit for step down converter.
b.
Study the performance of the down converter for various loads with (i) MOSFET (ii) IGBT and (ii) Thyristor as the switch.
EQUIPMENTS NEEDED 1.
Oscilloscope
2.
Digital Multimeter
3.
BNC to Test Probe
4.
ST2724 Step Down Chopper and power supply.
5.
Patch Cords & Operating manual
CONNECTION DIAGRAM:
Figure 2.1: PWM generation circuit
PROCEDURE FOR STUDYING THE PWM CIRCUIT. Make sure that there is no connection on the board initially. 1. Make the connections according to Figure 1.1. 2. Rotate the frequency control potentiometer gradually in the anticlockwise direction. 3. Similarly, rotate the PWM control potentiometer also in the anticlockwise direction. EEE/INSRT F342 Power Electronics
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4. Switch ‘On’ the power supply. 5. Observe the square wave output between Test Points TP1 with respect to TP2. 6. Observe the triangular wave output at Test Points TP3 with respect to the ground. 7. Vary the frequency control potentiometer and observe the variation in frequency. 8. Observe the reference voltage (Vref ) at Test Points TP4 with respect to ground. 9. Vary the PWM control potentiometer & observe the change in voltage either on the multimeter or on the oscilloscope by putting it into the DC Mode.
10. Observe the PWM signal at PWM pulse with respect to ground. 11. Set the frequency control potentiometer to some value, then vary the PWM control potentiometer & observe the PWM pulse.
12. Record the maximum & minimum frequency and pulse width in the observation table 1.1.
OBSERVATION TABLE 2.1: Minimum Frequency (Hz)
Maximum Frequency (Hz)
Minimum Pulse Width (%)
Maximum Pulse Width (%)
Figure 1.2 : Step Down converter
PROCEDURE FOR STUDYING THE DOWN CONVERTER WITH VARIOUS LOADS. Make sure that there is no connection on the board initially. 1. Switch on the power supply. 2. Set the frequency of PWM pulse by frequency control potentiometer at 4KHz. 3. Switch off the power supply. 4. Connect the power supply +24V & ground at their indicated positions. 5. Connect the MOSFET at chopper section in step down chopper configuration. 6. Connect the PWM pulse from the PWM circuit to the Gate (G) of the MOSFET. Connect the Gnd from the PWM circuit to the Source (S) of the MOSFET.
7. Connect the load (R load without L, RL load without L and motor load without L) at its indicated position.
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8. Switch ‘On’ the power supply. Connect the oscilloscope and vary the PWM control potentiometer & observe switch voltage, diode voltage and output voltage waveform across the load .
9.
Connect the multimeter in DC mode. Vary the PWM control potentiometer and observe the output voltage across the load, switch and diode. Verify the output DC voltage with the theoretical value.
10. Switch ‘Off ’ the power supply. 11. Disconnect PWM pulse and input voltage from the power circuit. Set the frequency of PWM pulse by frequency control potentiometer at 500Hz & repeat the experiment.
12. Repeat the experiment for different switches (IGBT and thyristor) at different duty ratios.
OBSERVATION TABLE 2.2 R- Load S. No.
Device
Frequency (Hz)
PWM (%)
1
MOSFET
4kHz
40%
2
MOSFET
4kHz
80%
3
MOSFET
500Hz
40%
4
MOSFET
500Hz
80%
5
IGBT
4kHz
40%
6
IGBT
4kHz
80%
7
IGBT
500Hz
40%
8
IGBT
500Hz
80%
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Measured Output Voltage (V)
Theoretical Output Voltage (V)
Measured voltage across the device (V)
Measured voltage across the diode (V)
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RL- Load S. No.
Device
Frequency (Hz)
PWM (%)
1
MOSFET
4kHz
40%
2
MOSFET
4kHz
80%
3
MOSFET
500Hz
40%
4
MOSFET
500Hz
80%
5
IGBT
4kHz
40%
6
IGBT
4kHz
80%
7
IGBT
500Hz
40%
8
IGBT
500Hz
80%
Measured Output Voltage (V)
Theoretical Output Voltage (V)
Measured voltage across the device (V)
Measured voltage across the diode (V)
Motor Load S. No.
Device
Frequency (Hz)
PWM (%)
1
MOSFET
4kHz
40%
2
MOSFET
4kHz
80%
3
MOSFET
500Hz
40%
4
MOSFET
500Hz
80%
5
IGBT
4kHz
40%
6
IGBT
4kHz
80%
7
IGBT
500Hz
40%
8
IGBT
500Hz
80%
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Measured Output Voltage (V)
Theoretical Output Voltage (V)
Measured voltage across the device (V)
Measured voltage across the diode (V)
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GRAPHS 1. Draw the graphs of PWM output, output voltage and diode voltage at switching frequency 500Hz for duty ratios 0.4 for RL load with filter inductor when MOSFET is used as a switch. 2. Draw the graphs of PWM output, output voltage and diode voltage at switching frequency 4 k Hz for duty ratios 0.8 for RL load with filter inductor when MOSFET is used as a switch. 3. Draw the graphs of PWM output, output voltage and diode voltage at switching frequency 500Hz for duty ratios 0.4 for moto r load with filter inductor when MOSFET is used as a switch. 4. Draw the graphs of PWM output, output voltage and diode voltage at switching frequency 4 k Hz for duty ratios 0.8 for moto r load with filter inductor when MOSFET is used as a switch.
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Specification for the ST2724 Step down converter On Board PWM Circuit
:
Triangular Comparator Circuit
Frequency Variation
:
27 Hz to 5 KHz (approximately) PWM
Variation
:
0-90%
Inductor
:
68 mH
R load
:
1kΩ
RL Load
:
1kΩ, 10mH
DC Geared Motor
:
24V/ 0.5A, 100 RPM
Interconnections
:
2 mm sockets
MOSFET Assembly
:
MOSFET IRFZ44N, 55V, 49A IGBT
Assembly Assembly :
: :
IGBT G4BC20S, 600V, 10A Transistor Transistor TIP122, 100V, 5A SCR Assembly
SCR TYN 616, 600 V, 16A Fuse
:
DC Power Supply (SMPS)
:
Power Supply
:
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1A
12V; 0.5A, 24V; 1A 230 V
10%; 50 Hz
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EXPERIMENT No. 3
STUDY OF BOOST CONVERTER Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To Study the PWM generation Circuit for Boost converter.
b.
Study the performance of the Boost converter for different values of L,C and load
EQUIPMENTS NEEDED 1.
Oscilloscope
2.
Digital Multimeter
3.
BNC to Test Probe
4.
Techbook Scientech 2727 and power supply.
5.
Patch Cords & Operating manual
CIRCUIT DIAGRAM:
Figure 3.1 Power circuit for Boost converter
PROCEDURE FOR STUDYING THE PWM CIRCUIT. Make sure that there is no connection on the board initially. 1. Connect the Power supply (SMPS) to Techbook Scientech 2727. 2.
Switch on the instrument.
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3. Observe the output of PWM Generation block at TP1 with respect to GND on oscilloscope. 4.
Observe the output of optical isolation block at TP2 with respect to ISO_GND on oscilloscope.
5.
Observe the Gate pulse at TP3 with respect Vs.
6.
Vary the frequency control potentiometer to observe frequency variation on the oscilloscope.
7.
Vary the Duty Cycle control potentiometer to observe the duty cycle variation on the oscilloscope.
8. Switch OFF the Power supply Unit. Remove the test probes from ST 2729.
OBSERVATION TABLE 3.1: Minimum Frequency (Hz)
Maximum Frequency (Hz)
Minimum Pulse Width (%)
Maximum Pulse Width (%)
PROCEDURE FOR STUDYING THE BOOST CONVERTER Make sure that there is no connection on the board initially. 1. Switch ON the Power supply unit. 2. Set the chopping frequency at 20 KHz by the frequency potentiometer. 3. Set the PWM duty cycle at minimum by varying Duty cycle control potentiometer. 4. Switch OFF the Power supply unit. 5. Connect one end of inductor L1 to the diode D1 & the other end of inductor L1 to positive terminal of capacitor C1.
6. Connect the one end of the RL1 to the one end of the load terminal & other terminal of the RL1 to the other end of the load.
7. Connect the GATE pulse to the gate of the T1 (IGBT). 8. Connect +24V and ISO_GND to the boost configuration. 9. Switch on the instrument. 10. Vary the PWM control potentiometer at different pulse width. Observe the variable DC voltage across the load.
11. Verify the output DC voltage with the theoretical value. 12. Connect the multimeter in DC mode and vary the PWM control potentiometer and observe the output voltage across the load, switch and diode.
13. Connect the oscilloscope and vary the PWM control potentiometer & observe the waveforms of inductor current, diode current, output capacitor ripple voltage, and capacitor current . (For output ripple voltage, measure Vo in ac coupling.)
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14. Switch ‘Off ’ the power supply. 15. Repeat the experiment for different values of L, C and load. 16. Disconnect all the connections from the board.
OBSERVATION TABLE 3.2 Load = R1//R2
Ω
S. No.
Inductor value (µH)
Capacitor (µF)
1
L1
C1
20%
2
L1
C1
33%
3
L1+L2
C1
20%
4
L1+L2
C1
33%
PWM (%)
Measured Output Voltage (V)
Theoretica l Output Voltage (V)
Measured voltage across the switch (V)
Measured voltage across the diode (V)
GRAPHS 1.
Draw the graphs of PWM output, inductor current, diode current, capacitor current and voltage
across the switch for duty ratio of 0.33 for the values of L1+L2 and C1 for Boost converter. 2.
Draw the graphs of PWM output, inductor current, diode current, capacitor current and vol tage across the switch for duty ratio of 0.2 for the values of L1+L2 and C1 for Boost converter.
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Specification for the ST2727 Boost converter SMPS : +/- 12V@ 500mA, +5V@250mA SMPS : +/- 12V@ 500mA, +5V@250mA SMPS : +/15V@1A SMPS : +24 V@1A for DC rail
Input DC Voltage
: 24V/1A
PWM Frequency Variation
: 1 KHz to 22 KHz
Duty Cycle Variation
: 10% to 45%
Power Isolation Section
: Single channel, 10x
Power device
: IGBT TOSHIBA 20JT101
Diode
: UF4007
MOSFET/ IGBT Driver
: MC33153
Rsense
: 0.1Ω
Turn off Snubber
: 100E 1W & 0.1µF 250V
Dimensions (mm)
: W 326 x D 252 x H 52
Power Supply
: 110V - 260V AC, 50/60Hz
Weight
: 1.5Kg (approximately)
Operating Conditions
: 0-400 C, 85% RH
L1
L2
L3
C1
C2
C3
RL1
RL2
1.5mH
404uH
User
1000uF/63V
470uF/63V
220uF/63V
75 Ω/ 25W
75Ω/ 25W
Please use external load for observing output power more than 15W. The maximum output power should not
exceed 20W.
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EXPERIMENT No. 4
STUDY OF FORWARD CONVERTER Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To Study the PWM generation Circuit for forward converter.
b.
Study the performance of the forward converter for various loads.
EQUIPMENTS NEEDED 1.
Oscilloscope
2.
Digital Multimeter
3.
BNC to Test Probe
4.
Scientech 2730 forward converter and power supply.
5.
Patch Cords & Operating manual.
Figure 4.1 Power circuit for a practical forward converter
PROCEDURE FOR STUDYING THE PWM CIRCUIT Make sure that there is no connection on the board initially. 1. Switch on the instrument. 2. Observe the output of PWM Generation section with respect to GND on oscilloscope. 3.
Vary the duty cycle control potentiometer to observe duty cycle variation on oscilloscope.
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4.
Vary the frequency control potentiometer to observe frequency variation on oscilloscope.
5.
Observe the PWM at the output of optical isolation block with respect to ISO_GND. PWM gets inverted at this point.
6.
Observe the output of IGBT Driver block with respect ISO_GND.
7.
Switch OFF the Power supply Unit.
OBSERVATION TABLE 4.1: Minimum Frequency (Hz)
Maximum Frequency (Hz)
Minimum Pulse Width (%)
Maximum Pulse Width (%)
PROCEDURE FOR STUDYING THE FORWARD CONVERTER WITH VARIOUS LOADS. Make sure that there is no connection on the board initially. 1. Switch ON the Power supply unit. 2. Set the chopping frequency at 90 KHz by the frequency potentiometer. 3. Set the PWM duty cycle at minimum by varying Duty cycle control potentiometer. 4.
Switch OFF the Power supply unit.
5.
Connect one end of inductor L1 and L2 in series to cathode of the diode D1.
6.
Connect the capacitor C1 between at the output.
7.
Connect the GATE pulse to the gate of the IGBT.
8.
Connect the Load RL1 and RL2 in parallel to load terminals.
9.
Connect +24V and ISO_GND to the Forward configuration.
10. Switch on the instrument. 11. Vary the PWM control potentiometer at different pulse width. Observe the variable DC voltage across the load. Verify the output DC voltage with the theoretical value. 12. Connect the multimeter in DC mode vary the PWM control potentiometer and observe the output voltage across the load, switch and diode. 13. Connect the oscilloscope and vary the PWM control potentiometer & observe the
waveforms of inductor current, switch (MOSFET) current, output capacitor (C 1) ripple voltage, and capacitor current. 14. Switch ‘Off ’ the power supply. 15. Repeat the experiment for different values of L , C and load values. 16. Connect the output LC filter and observe the change in output voltage average value (using DMM) and the ripple voltage (on DSO). 17. Disconnect all the connections from the board. EEE/INSRT F342 Power Electronics
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OBSERVATION TABLE 4.2 Load = R1//R2
Ω
S. No.
Inductor value (µH)
Capacitor (µF)
PWM (%)
1
L1+L2
C1
20%
2
L1+L2
C1
40%
3
L1
C1
20%
4
L1
C1
40%
Measured Output Voltage (V)
Theoretical Output Voltage (V)
Measured voltage across the switch (V)
Measured voltage across the diode (V)
GRAPHS 1.
Draw the graphs of PWM output, inductor current, switch current, capacitor current and voltage
across the switch for duty ratio of 0.2 with L1 ,C1 and load for Forward converter and switching frequency 90kHz. 2.
Draw the graphs of PWM output, inductor current, switch current, capacitor current and voltage across the switch for duty ratio of 0.4 with L1+L2 ,C1 and load for Forward converter and switching frequency 90kHz.
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Specification for the ST2730 Forward converter
SMPS: +/- 12V@ 500mA, +5V@250mA SMPS: +/- 12V@ 500mA, +5V@250mA SMPS: +/15V@1A SMPS: +24 V@1A for DC rail.
Input DC Voltage
: 4V/1A
PWM Frequency Variation
: 8 KHz to 95 KHz
Duty Cycle Variation
: 8% to 35%
Isolation 3 winding transformer: 6:10:6 ((NP:NS:NT) ,NT → Reset winding (terLary winding) Power device
: MOSFET IRF450
Diode
: F4007
MOSFET/ IGBT Driver
: C33153
Turn off Snubber
: 100E 1W & 2.2nf 250V Rsense
: 0.1Ω Power Isolation Section L1 91uH
: Single channel, 10x L2 174uH
C1 1000uF/63V
C2 470uF/63V
RL1 75E /25W
RL2 75E /25W
Please use external load for observing output power more than 15W. The maximum output power should not
exceed 20W.
EEE/INSRT F342 Power Electronics
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EXPERIMENT No. 5 STUDY OF SINGLE PHASE SEMI-CONTROLLED AND FULLY CONTROLLED RECTIFIER. Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To study the performance of the Single Phase Semi Converter with Ramp Comparator with (i) Lamp Load and (ii) Motor Load.
b.
To study the performance of the Single Phase Bridge Controlled Rectifier with Ramp, Cosine Comparator, with Lamp Load.
EQUIPMENTS NEEDED 1.
ST2700 High Voltage Power Electronics Lab set up
2.
2mm Patch Cord
3.
4mm Patch Cords
4.
Oscilloscope
5.
Voltage probes and clamp-on current probes (Tektronix A621)
6.
Multimeter
PRECAUTIONS: Sequences of the switching are to be followed. Make sure that for all the measurements above 50V, power isolation section (Powerscope) provided on the set-up is to be used. Attenuation for the power isolation unit should be kept at 100x for voltages higher than 100V. Make sure that Ammeters are connected in series with and Voltmeters are connected parallel across the load respectively. Make sure use appropriate range in case of voltmeter/ammeter are within the proper range. Verify the type (AC/DC) before connection.
CIRCUIT DIAGRAM:
Figure 5.1 Single Phase Semi-Converter EEE/INSRT F342 Power Electronics
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PROCEDURE FOR STUDYING THE PERFORMANCE OF THE SINGLE PHASE SEMI-CONVERTER. Make sure that there is no connection on the board initially. 1.
Make Connections according to Figure 4.1.
2.
Connect Line Terminal (L) from single phase supply to anode of SCR1 or cathode of diode D2 and connect neutral terminal (N) to anode of SCR2 or cathode of diode D1.
3.
Connect the one terminal of load from Load Assembly to common cathode terminal of SCR1 and SCR2 and other terminal of load is connect to common anode terminal of diode D1 and diode D2 .
4.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from ramp comparator firing circuit.
5.
Connect gate pulse G3 at gate (G) of SCR2 and connect K3 at cathode of SCR2 from ramp comparator firing circuit.
6.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A.
7.
Switch ATT of A is at ‘x 100 ’ position and switch of coupling of A should be at ‘DC’ position.
8.
Connect input of Power Scope A to the load.
9.
Connect the Lamp at the Load. Connect the DC Voltmeter, Ammeter at the load.
10. Verify the connections before switch on the MCB of single phase supply. 11. Switch on MCB of Single Phase Supply and observe the waveforms on the oscilloscope . 12. In single phase semi converter common cathode configuration output load voltage is positive 0 to 205V DC variable (approximately) 13. Take the readings and tabulate in Observation Table 4.1. 14. Repeat the steps 1-14 for Motor Load.
OBSERVATION TABLE 5.1:
S.No
Type of Load
Firing Angle (α)
Measured Output Voltage (Vo)
Calculated Output Voltage (Vo)
60 o
1
Lamp Load o
2
90
3
120
4
Motor Load
EEE/INSRT F342 Power Electronics
90
o
o
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CONNECTION DIAGRAM:
Figure 5.2 Single Phase Bridge Controlled Rectifier
PROCEDURE FOR STUDYING THE PERFORMANCE OF THE SINGLE PHASE CONTROLLED RECTIFIER. Make sure that there is no connection on the board initially. 1.
Make Connections according to Figure 4.2.
2.
Connect +12V, +5V and ground (GND) and connect 18-0-18 at ramp comparator firing circuit from single phase low voltage power supply.
3.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from ramp comparator firing circuit. Connect gate pulse G2 at gate (G) of SCR2 and connect K2 at cathode of SCR2 from ramp comparator firing circuit.
4.
Connect gate pulse G3 at gate (G) of SCR3 and connect K3 at cathode of SCR2 from ramp comparator firing circuit. Connect gate pulse G4 at gate (G) of SCR4 and connect K4 at cathode of SCR4 from ramp comparator firing circuit.
5.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A.
6.
Switch of ATT of A is at ‘x 100’ position and switch of coupling of A should be at ‘DC’ position.
7.
Connect input of Power Scope A to the load.
8.
Connect the Lamp at the Load.
9.
Connect the DC Voltmeter, Ammeter at the load.
10. Verify the connections before switch on the MCB of single phase supply. 11. Switch on MCB of Single Phase Supply and observe the waveform of load voltage on the oscilloscope. 12. Take the readings and tabulate in Observation Table 4.2. 3. Repeat steps 1-14 using Cosine Comparator for lamp load. (Caution: Verify that the sequence of firing for the switches is in synchronism with the input voltage. If not, it may lead to erroneous operation and may damage the system.)
EEE/INSRT F342 Power Electronics
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OBSERVATION TABLE 5.2 Ramp comparator firing scheme S.No
Type of Load
Firing Angle (α)
1
45
o
2
60
o
90
o
3
Lamp Load
Vref
Measured Output Voltage (Vo)
Calculated Output Voltage (Vo)
GRAPHS (a) Draw graphs of line voltage (VAN), Output Voltage (Vo), Output Current (Io), and Switch Voltage 0 (VT1) with respect to time for semiconverter with Lamp load at 60 . (b) Draw graphs of line voltage (VAN), Output Voltage (Vo), Output Current (Io), and Switch Voltage 0 (VT1) with respect to time for semiconverter with motor load at 90 . (c) Draw graphs of line voltage (VAN), Output Voltage (Vo), Output Current (Io), and Switch Voltage 0 (VT1) with respect to time for full bridge rectifier with lamp load at 60 . (d) Draw graphs of line voltage (VAN), Output Voltage (Vo), Output Current (Io), and Switch Voltage 0 (VT1) with respect to time for full bridge rectifier with motor load at 90 .
EEE/INSRT F342 Power Electronics
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EXPERIMENT No. 6
STUDY OF THREE-PHASE SEMI CONVERTER Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To study of Three Phase Firing Circuit.
b.
To Study Three Phase Semi Converter with Lamp Load/heater load.
EQUIPMENTS NEEDED 1. ST2700 High Voltage Power Electronics Lab 2. 2mm Patch Cords, 4mm Patch Cords 3. Oscilloscope 4. Voltage probes and clamp-on current probes ((Tektronix A621) 5. Multimeter 6. Heater load and lamp loads(4 lamps).
PRECAUTIONS: Sequential order of switching is to be followed. Make sure that Analog Ammeter and Voltmeter are connected in series and parallel across load respectively. Always turn on the High voltage three phase MCB before turning on the low voltage 3 phase MCB. That is, do not apply gate signals, before the power circuit is energized. Follow the reverse order while switching off.
CONNECTION DIAGRAM:
Figure 6.1 Three Phase Semi Converter
EEE/INSRT F342 Power Electronics
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PROCEDURE TO STUDY THE 3-PHASE FIRING CIRCUIT: Make sure that there is no connection on the Work Bench initially 1. 2.
Switch on the three phase MCB of back panel. Red, Yellow and Blue indicator glow at front panel. Connect the R phase, Y phase, B phase and neutral (N) on three phase firing circuit from three phase
low voltage power supply. 3.
Connect +12V and ground (GND) on three phase firing circuit from single phase low voltage power supply.
4.
Switch on the oscilloscope. Connect BNC to Test Probe cable at CH1 of oscilloscope.
5.
Switch on MCB of three phase low voltage power supply. Observe the R phase, Y phase and B phase waveforms with respect to neutral.
6.
Observe the output of ramp generator at point of R,Y and B phase one by one at their respective test points with respect to neutral (N).
7. Observe reference voltage at point Vref with respect to neutral vary the firing angle control potentiometer and observe the variation in Vref. 8.
Observe the output of ramp comparator 1, 2 and 3 at point output of ramp comparator which is a square wave and another test point below it also shows square wave that is 180 phase shift to first square ˚
wave and by varying the firing angle control potentiometer vary the pulse width of square wave. 9.
Now connect CH1 of the oscilloscope to R with respect to N to measure VRN. Connect CH2 of the oscilloscope to the gate pulse at G1 with respect to K1. Vary the firing angle control potentiometer and observe the variation in gate pulse with respect to VRN. Observe the gate pulses G3 with respect to K3 and G5 with respect to K5 with V RN as the time reference waveform. (Caution: Ensure that proper sequence of firing pulses are maintained for the switches. If not, it may lead to erroneous operation and may damage the system.)
PROCEDURE FOR STUDYING THE THREE PHASE SEMI CONVERTER. Make sure that there is no connection on the board initially. 1.
Connect the R phase, Y phase, B phase and neutral (N) on three phase firing circuit from three phase low voltage power supply.
2.
Connect +12V and ground (GND) on three phase firing circuit from single phase low voltage power supply.
3.
Make the power circuit connections according to Figure 5.1.
4.
Connect the one terminal of load from load assembly to common cathode terminal of three phase semi converter and other terminal of load is connect to common anode terminal of three phase semi converter.
Connect the 4 lamps and heater load in series as the load to the converter.
EEE/INSRT F342 Power Electronics
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5.
Power on three phase low voltage power supply and single phase low voltage power supply and set the o
firing angle α= 45 with keeping VRN (low voltage) as the time reference. Switch off the supply, keeping the firing control knob at the same position. 6.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from three phase firing circuit. Similarly, connect gate pulse G3 at gate (G) of SCR2 and connect K3 at cathode of SCR2, and gate pulse G5 at gate (G) of SCR3 and connect K5 at cathode of SCR3 from three phase firing circuit.
7.
Connect input of Power Scope A to the line voltage VRY( HV). Connect input of Power Scope B to the load. Connect the DMM at the load to measure the output DC voltage across the load.
8.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A and CH2 of oscilloscope to Power Scope B.
9.
Switch ‘ATT’ of A and B is to be kept at ‘x 100 ’ position and switch of coupling of A and B should be at ‘DC’ position.
10. Verify the connections before switch on the MCB of single phase supply.
11. Switch on MCB of Three Phase Supply and three phase low voltage power supply (respectively) and observe the waveforms on the oscilloscope. Switch off the MCBs in the reverse order. (Low voltage 3 phase MCB first, Three phase high voltage MCB second and 1 phase MCB third.) 12. Keeping VRY in Power Scope A (and CH1) as time reference, connect Power scope B (and CH2) across VT1 and note the waveform. Repeat the procedure and note down Vo, VD1, IT1, and IIN using CH2 with VRY as the time reference. 13. Switch off all the MCBs. Disconnect G1-K1, G3-K3 and G5-K5 from the power circuit. Now repeat o o steps 5-12 with α= 60 and 90 .
OBSERVATION TABLE 6.1: Vs(line-line)= S.No
Type of Load
1 2 3
Lamp Load+ Heater load
V Firing Angle (α) 45
o
60
o
90
o
Measured Output Voltage (Vo)
EEE/INSRT F342 Power Electronics
Calculated Output Voltage (Vo)
Measured Output Current (Io)
Output Power (Po)
Input current IA(RMS)
Power factor
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GRAPHS
(a) Draw the graphs of Phase Voltage (VRN), Line Voltage (VRY) waveforms and gate pulses VG1K1, VG3K3 , VG5K5 o
for α=60 .
(b) Draw the graphs of Phase Voltage (VRN), Line Voltage (VRY) Output Voltage (Vo), and Thyristor Voltage o
(VT1) , and IIN with respect to time for α= 90 .
EEE/INSRT F342 Power Electronics
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EXPERIMENT No. 7
STUDY OF SINGLE PHASE AC/AC CONVERTERS Name
ID No.
Sec.No
Batch No.
Date
Marks obtained
Instructor’s signature
OBJECTIVES a.
To study single phase full wave ac voltage controller with (a) lamp load. (b) motor load.
b. To Study single phase cycloconverter with (a) lamp load (b) motor load.
EQUIPMENTS NEEDED 1. ST2700 High Voltage Power Electronics Lab 2. 2mm Patch Cord, 4mm Patch Cords 4. Oscilloscope 5. Voltage probes and clamp-on current probes ((Tektronix A621) 6. Multimeter
PRECAUTIONS: Make sure that Analog Ammeter and Voltmeter are connected in series and parallel across load respectively.
CONNECTION DIAGRAM:
Figure 7.1 Single Phase Full-Wave Ac Voltage Controller
EEE/INSRT F342 Power Electronics
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PROCEDURE TO STUDY THE SINGLE PHASE FULL-WAVE AC VOLTAGE CONTROLLER CIRCUIT: Make sure that there is no connection on the Work Bench initially 1.
Switch on the three phase MCB of back panel. Red, Yellow and Blue indicator glow at front panel.
2.
Connect +12V, +5V and ground (GND) and connect 18-0-18 at ramp comparator firing circuit from single phase low voltage power supply.
3.
Connect the power circuit as per Figure 6.1.
4.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from ramp comparator firing circuit.
5.
Connect gate pulse G3 at gate (G) of SCR2 and connect K3 at cathode of SCR2 from ramp comparator firing circuit.
6.
Verify the connections before switch on the MCB of single phase supply.
7.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A.
8.
Switch of ATT of A is at ‘x 100’ position and switch of coupling of A should be at ‘DC’ position.
9.
Connect input of Power Scope A to the load. Connect the Lamp Motor at the Load.
10. Connect the AC Voltmeter at the load to measure the output AC voltage across the load. 11. Switch on MCB of Single Phase Supply and observe the waveforms of Input voltage, input current, voltage across SCR1, and output voltage at the load for various firing angles using CRO. 12. Observe the Input voltage, input current, voltage across SCR1, and output voltage at the load for various firing angles using multimeter. 13. Repeat the experiment with the motor load.
Figure 7.2 Single Phase Full-Wave Ac Voltage Controller
EEE/INSRT F342 Power Electronics
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PROCEDURE TO STUDY THE SINGLE PHASE CYCLOCONVERTER CIRCUIT: Make sure that there is no connection on the Work Bench initially 1.
Switch on the three phase MCB of back panel. Red, Yellow and Blue indicator glow at front panel.
2.
Connect +12V, +5V, -5V and ground (GND) and connect 18-0-18 at cycloconverter firing circuit from single phase low voltage power supply.
3.
Connect the power circuit as per Fig. 6.2.
4.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from cycloconverter firing circuit. Similarly, connect gate pulse G3 at gate (G) of SCR4 and connect K3 at cathode of SCR4, gate pulse G2 at gate (G) of SCR2 and connect K2 at cathode of SCR2 and gate pulse G4 at gate (G) of SCR5 and connect K4 at cathode of SCR5.
5.
Verify the connections before switch on the MCB of single phase supply.
6.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A. Connect input of Power Scope A to the load.
7.
Switch of ATT of A is at ‘x 100’ position and switch of coupling of A should be at ‘DC’ position.
8.
Connect the Lamp at the Load. Connect the AC Voltmeter at the load to measure the output AC voltage across the load.
9.
Switch on MCB of single phase supply and observe the waveforms of Input voltage, input current, voltage across SCR1, and output voltage at the load for various firing angles using CRO.
10. Observe the Input voltage, input current, and output voltage at the load for various firing angles using multimeter (AC mode).
OBSERVATION TABLE 7.1: AC/AC PHASE CONTROLLED CONVERTER Vs(line-line)
=
Frequency of Input voltage
=
Frequency of output voltage S.No 1 2 3
V Hz
=
Hz
Type of Load
Firing Angle (α)
Lamp 1 + Lamp 2 load
60
o
90
o
90
o
Motor Load
EEE/INSRT F342 Power Electronics
Measured Output Voltage (Vo)
Calculated Output Voltage (Vo)
Input current IA(RMS)
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MODEL WAVEFORM
OBSERVATION TABLE 7.2: SINGLE PHASE CYCLOCONVERTER Vs(line-line)
=
V
Frequency of Input voltage
=
Hz
Frequency of output voltage
=
S.No
1 2
Type of Load Lamp 1+ Lamp 2 Load
EEE/INSRT F342 Power Electronics
Hz Firing Angle (α) 45
o
60
o
Measured Output Voltage (Vo)
Calculated Output Voltage (Vo)
Input current IA(RMS)
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