EE 1303 POWER ELECTRONICS LABORATORY 0 0 3 100

AIM

To study the characteristics of switching devices and its applications in rectifier inverter, chopper and resonant converter.

List of experiments with objectives and exercises

1. Characteristics of SCR

2. Characteristics of TRIAC

3. Characteristics of MOSFET and IGBT

4. Transient characteristics of SCR and

MOSFET

5. AC to DC fully controlled converter

6. AC to DC half-controlled converter

7. Step down and step up MOSFET based choppers

8. IGBT based single-phase PWM inverter

9. IGBT based three-phase PWM inverter

10. Resonant dc-to-dc converter

P = 45 Total = 45

Detailed Syllabus

1. Characteristics of SCR

Objectives

1. Obtaining the anode (VAK – IA) forward conduction characteristics including the measurement of holding and latching currents.

2. Application of single SCR as half-wave rectifier.

Exercise

1. Conduct an experiment and obtain the anode forward conduction characteristics of the given SCR.

2. By conducting an experiment find the latching and holding currents of the given SCR.( high current SCR to be given for this exercise)

3. Demonstrate how a single phase half wave rectifier circuit can be implemented using a given SCR, AC power source and RC firing circuit.

2. Characteristics of TRIAC

Objectives

1. Obtaining the VI characteristics, both forward and reverse conduction.

2. Application of TRIAC along with suitable (R-C firing circuit based or otherwise) firing circuit, as single-phase A.C phase controller for illumination control.

Exercise

1. Obtain the forward conduction characteristics of the given TRIAC.

2. Obtain the reverse conduction characteristics of the given TRIAC.

3. Demostrate how a single- phase AC phase controller can be implemented for controlling the illumination of lamp, using given TRIAC and RC triggering circuit.

3. Characteristics of MOSFET and IGBT

Objective

Obtaining steady state output characteristics of both MOSFET and IGBT.

Exercise

1. Obtain the steady – state output – side characteristics of the given MOSFET, for a specified value of gate – source voltage.

2. Obtain the steady – state output – side characteristics of the given IGBT, for a specified value of gate emitter voltage.

3. Identify whether given switch is MOSFET or IGBT by finding the output – side characteristics.

4. Transient characteristics of SCR and MOSFET

Objective

Studying the switching characteristics, turn-on and turn-off of both SCR and

MOSFET.

Exercise

1. Capture and explain the turn-on characteristics of the given SCR.

2. Capture and explain the turn – off characteristics of the given SCR.

3. Obtain and explain both turning ‘ON’ and turn ‘OFF’ characteristics of given MOSFET.

5. AC to DC fully controlled converter

Objective

Studying the operation of single-phase and three-phase fully controlled converter fed R and R-L (i.e., Rectifier mode only) and determination of typical performance factors: Rectification ratio, form factor, ripple factor.

Exercise

1. Given the input AC voltage and required output DC voltage, theoretically calculate the firing angle required and practically verify the same by implementing a single – phase fully- controlled converter fed R-L load.

2. Theoretically calculate the overlap angle of given single phase fully controlled converter fed R-L load with Ls (source inductance) included practically verify the same by conducting an experiment.

3. Obtain the typical performance factors of the given single phase fully controlled converter fed R and R-L loads.

6. AC to DC half-controlled converter

Objective

1. Studying the operation of a single-phase and three-phase half controlled converter fed R and R-L loads.

1. Determination of typical performance parameters.

2. Comparative study with fully controlled converter.

Exercise

1. Given the input AC voltage and required output DC voltage, theoretically calculate the firing angle required and practically verify the same by implementing a single- phase half controlled converter fed R-L load.

2. Determine the typical performance factors of the given single phase half – controlled converter fed R-L or R load, by conducting a suitable experiment.

3. Given the AC input voltage and output DC voltage required (assumed positive output voltage), compare the performance factors of

a. fully- controlled converter fed R-L load

b. Half – controlled converter fed R-L load

Show the differences practically by conducting a suitable experiment.

7. Step down and step up MOSFET based choppers

Objective

1. Studying the operation and gain characteristics of buck and boost type MOSFET based choppers.

Exercise

1. Obtain the gain characteristics (i.e output voltage Vs input voltage) of given buck or step down type, MOSFET based chopper.

2. Obtain the given characteristics (i.e output voltage Vs input voltage) of given boost or step-up type, MOSFET based chopper.

8. IGBT based single-phase PWM inverter

Objective

1. Studying of high frequency switched IGBT based single-phase PWM inverter.

2. Voltage magnitude control using modulation index.

3. Studying the effects of over modulation.

Exercise

1. Study the output voltage waveform obtained of the given IGBT based single phase PWM inverter and obtain its harmonic spectrum.

2. Demostrate how the rms fundamental output voltage of PWM inverter can be changed by changing the modulation index. For a given DC output voltage and required AC output voltage, theroritically calculate the modulation index and also practically verify the same.

3. Practically show that over modulation of sine – triangle PWM inverter leads to introduction of lower order harmonics into output voltage.

9. IGBT based three-phase PWM inverter

Objective

1. Studying various PWM techniques, like sinusoidal and multiple PWM methodologies , applicable to three-phase voltage source inverter for both UPS and AC drive applications.

Exercise

1. Compare the lower order harmonic contents of sinusoidal PWM and multiple / equal PWM based inverters, theoretically. Also practically demonstrate the same.

2. Show how the output frequency of three phase PWM inverter can be regulated of 50 Hz for UPS applications and how the frequency can be varied for getting variable frequency AC drives applications using the given three phase PWM module.

10. Resonant dc-to-dc converter

Objective

Studying the switching mode power supply (isolated) topologies employing resonant switching, zero current switching and/or zero voltage switching.

Exercise

1. Demonstrate how zero- current switching can be incorporated in a resonant converter, by considering a series loaded series resonant DC to DC converter on switching frequency below half of the resonating frequency.

2. Demonstrate how zero – voltage switching can be incorporated in a resonant converter, by considering a series loaded resonant DC to DC converter on switching frequency above half of the resonating frequency but below the resonant frequency.

AIM

To study the characteristics of switching devices and its applications in rectifier inverter, chopper and resonant converter.

List of experiments with objectives and exercises

1. Characteristics of SCR

2. Characteristics of TRIAC

3. Characteristics of MOSFET and IGBT

4. Transient characteristics of SCR and

MOSFET

5. AC to DC fully controlled converter

6. AC to DC half-controlled converter

7. Step down and step up MOSFET based choppers

8. IGBT based single-phase PWM inverter

9. IGBT based three-phase PWM inverter

10. Resonant dc-to-dc converter

P = 45 Total = 45

Detailed Syllabus

1. Characteristics of SCR

Objectives

1. Obtaining the anode (VAK – IA) forward conduction characteristics including the measurement of holding and latching currents.

2. Application of single SCR as half-wave rectifier.

Exercise

1. Conduct an experiment and obtain the anode forward conduction characteristics of the given SCR.

2. By conducting an experiment find the latching and holding currents of the given SCR.( high current SCR to be given for this exercise)

3. Demonstrate how a single phase half wave rectifier circuit can be implemented using a given SCR, AC power source and RC firing circuit.

2. Characteristics of TRIAC

Objectives

1. Obtaining the VI characteristics, both forward and reverse conduction.

2. Application of TRIAC along with suitable (R-C firing circuit based or otherwise) firing circuit, as single-phase A.C phase controller for illumination control.

Exercise

1. Obtain the forward conduction characteristics of the given TRIAC.

2. Obtain the reverse conduction characteristics of the given TRIAC.

3. Demostrate how a single- phase AC phase controller can be implemented for controlling the illumination of lamp, using given TRIAC and RC triggering circuit.

3. Characteristics of MOSFET and IGBT

Objective

Obtaining steady state output characteristics of both MOSFET and IGBT.

Exercise

1. Obtain the steady – state output – side characteristics of the given MOSFET, for a specified value of gate – source voltage.

2. Obtain the steady – state output – side characteristics of the given IGBT, for a specified value of gate emitter voltage.

3. Identify whether given switch is MOSFET or IGBT by finding the output – side characteristics.

4. Transient characteristics of SCR and MOSFET

Objective

Studying the switching characteristics, turn-on and turn-off of both SCR and

MOSFET.

Exercise

1. Capture and explain the turn-on characteristics of the given SCR.

2. Capture and explain the turn – off characteristics of the given SCR.

3. Obtain and explain both turning ‘ON’ and turn ‘OFF’ characteristics of given MOSFET.

5. AC to DC fully controlled converter

Objective

Studying the operation of single-phase and three-phase fully controlled converter fed R and R-L (i.e., Rectifier mode only) and determination of typical performance factors: Rectification ratio, form factor, ripple factor.

Exercise

1. Given the input AC voltage and required output DC voltage, theoretically calculate the firing angle required and practically verify the same by implementing a single – phase fully- controlled converter fed R-L load.

2. Theoretically calculate the overlap angle of given single phase fully controlled converter fed R-L load with Ls (source inductance) included practically verify the same by conducting an experiment.

3. Obtain the typical performance factors of the given single phase fully controlled converter fed R and R-L loads.

6. AC to DC half-controlled converter

Objective

1. Studying the operation of a single-phase and three-phase half controlled converter fed R and R-L loads.

1. Determination of typical performance parameters.

2. Comparative study with fully controlled converter.

Exercise

1. Given the input AC voltage and required output DC voltage, theoretically calculate the firing angle required and practically verify the same by implementing a single- phase half controlled converter fed R-L load.

2. Determine the typical performance factors of the given single phase half – controlled converter fed R-L or R load, by conducting a suitable experiment.

3. Given the AC input voltage and output DC voltage required (assumed positive output voltage), compare the performance factors of

a. fully- controlled converter fed R-L load

b. Half – controlled converter fed R-L load

Show the differences practically by conducting a suitable experiment.

7. Step down and step up MOSFET based choppers

Objective

1. Studying the operation and gain characteristics of buck and boost type MOSFET based choppers.

Exercise

1. Obtain the gain characteristics (i.e output voltage Vs input voltage) of given buck or step down type, MOSFET based chopper.

2. Obtain the given characteristics (i.e output voltage Vs input voltage) of given boost or step-up type, MOSFET based chopper.

8. IGBT based single-phase PWM inverter

Objective

1. Studying of high frequency switched IGBT based single-phase PWM inverter.

2. Voltage magnitude control using modulation index.

3. Studying the effects of over modulation.

Exercise

1. Study the output voltage waveform obtained of the given IGBT based single phase PWM inverter and obtain its harmonic spectrum.

2. Demostrate how the rms fundamental output voltage of PWM inverter can be changed by changing the modulation index. For a given DC output voltage and required AC output voltage, theroritically calculate the modulation index and also practically verify the same.

3. Practically show that over modulation of sine – triangle PWM inverter leads to introduction of lower order harmonics into output voltage.

9. IGBT based three-phase PWM inverter

Objective

1. Studying various PWM techniques, like sinusoidal and multiple PWM methodologies , applicable to three-phase voltage source inverter for both UPS and AC drive applications.

Exercise

1. Compare the lower order harmonic contents of sinusoidal PWM and multiple / equal PWM based inverters, theoretically. Also practically demonstrate the same.

2. Show how the output frequency of three phase PWM inverter can be regulated of 50 Hz for UPS applications and how the frequency can be varied for getting variable frequency AC drives applications using the given three phase PWM module.

10. Resonant dc-to-dc converter

Objective

Studying the switching mode power supply (isolated) topologies employing resonant switching, zero current switching and/or zero voltage switching.

Exercise

1. Demonstrate how zero- current switching can be incorporated in a resonant converter, by considering a series loaded series resonant DC to DC converter on switching frequency below half of the resonating frequency.

2. Demonstrate how zero – voltage switching can be incorporated in a resonant converter, by considering a series loaded resonant DC to DC converter on switching frequency above half of the resonating frequency but below the resonant frequency.

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