JNTUK B.Tech R23 3-1 Power Electronics subject EEE Branch imp questions

 UNIT - I: Power Semi-Conductor Devices

2 Marks Questions:

1. Explain the two transistor analogy of SCR.
2. What is the purpose of snubber circuit in SCR applications?
3. Compare the static characteristics of Power MOSFET and Power IGBT.

5 Marks Questions:

1. Derive the static and dynamic characteristics of Silicon Controlled Rectifier (SCR).
2. Explain the different turn-on and turn-off methods of SCR with neat diagrams.
3. Design a snubber circuit for SCR protection and explain its working principle.
4. Compare the switching characteristics of Power MOSFET and Power IGBT with numerical analysis.
5. Describe various triggering methods for SCR including R, RC and UJT triggering circuits.
6. Analyze the gate characteristics and switching behavior of Power IGBT with numerical problems.

UNIT - II: Single-phase AC-DC Converters

2 Marks Questions:

1. What is the difference between continuous and discontinuous conduction modes?
2. Define conversion ratio in single-phase controlled rectifiers.
3. What is the purpose of freewheeling diode in controlled rectifiers?

5 Marks Questions:

1. Analyze single-phase half-wave controlled rectifier with RL load and derive expression for output voltage.
2. Explain single-phase fully controlled bridge converter with R load and calculate average output voltage.
3. Analyze single-phase fully controlled bridge rectifier with RL load in continuous and discontinuous conduction modes.
4. Derive the expression for output voltage of single-phase semi-converter with RLE load.
5. Explain the operation of dual converter and analyze its different modes of operation.
6. Calculate the effect of source inductance on single-phase fully controlled bridge rectifier performance.

UNIT - III: Three-phase AC-DC Converters & AC-AC Converters

2 Marks Questions:

1. What are the advantages of three-phase rectifiers over single-phase rectifiers?
2. Define the principle of operation of cycloconverter.
3. What is phase control in AC-AC converters?

5 Marks Questions:

1. Analyze three-phase half-wave rectifier with R and RL loads and derive output voltage expressions.
2. Explain three-phase fully controlled rectifier operation and calculate average output voltage.
3. Analyze three-phase semi-converter with R and RL loads in different conduction modes.
4. Derive the expression for RMS output voltage in single-phase AC voltage controller with R load.
5. Explain single-phase step-down and step-up cycloconverter operation with waveforms.
6. Calculate output voltage and current for three-phase controlled rectifier with numerical problems.

UNIT - IV: DC-DC Converters

2 Marks Questions:

1. Define duty cycle and its significance in chopper circuits.
2. What is the difference between CCM and DCM in DC-DC converters?
3. Explain the principle of volt-second balance in DC-DC converters.

5 Marks Questions:

1. Analyze Buck converter operation in CCM and DCM modes and derive output voltage equations.
2. Explain Boost converter operation and derive expressions for output voltage in CCM and DCM.
3. Analyze Buck-Boost converter and derive output voltage expressions using volt-sec balance.
4. Calculate output voltage ripple and inductor current ripple in Buck converter with numerical analysis.
5. Explain different control techniques used in DC-DC converters including PWM control.
6. Compare the performance of Buck, Boost and Buck-Boost converters with numerical problems.

UNIT - V: DC-AC Converters

2 Marks Questions:

1. What is the difference between voltage source inverter and current source inverter?
2. Define modulation index in PWM inverters.
3. What are the advantages of PWM control in inverters?

5 Marks Questions:

1. Analyze single-phase half-bridge inverter with R and RL loads and draw output waveforms.
2. Explain single-phase full-bridge inverter operation with phase displacement control.
3. Analyze PWM inverter with bipolar and unipolar voltage switching techniques.
4. Explain three-phase square wave inverter with 120° and 180° conduction modes.
5. Describe Sinusoidal Pulse Width Modulation (SPWM) technique and its advantages.
6. Compare voltage source inverter (VSI) and current source inverter (CSI) with their applications.