POWER ELECTRONICS (EC-604 (C)) - Important Questions

Explain the basic structure, working and V-I / transfer characteristics of an IGBT with neat diagram.

Explain the basic structure (including fast recovery type) and static V-I characteristics of a power diode with diagram.

Explain the basic structure of a thyristor/SCR and its static V-I characteristics and modes of operation, including dynamic characteristics

Write short notes on any two from: methods of turning on a thyristor, step-up and step-down choppers, line-frequency phase-controlled rectifier using SCRs, single-phase bridge inverter

Describe the basic structure and V-I characteristics of a Power MOSFET and its operation in switching applications.

Discuss the different types of power diodes and their applications.

Write short notes on any two from: static and dynamic characteristics of thyristor, switched-mode power supply, basic structure and V-I characteristics of IGBT, three-phase bridge inverter

Describe the basic structure, operation, V-I characteristics and applications of a DIAC.

Draw and explain the transfer characteristic of a power MOSFET.

Explain series and parallel operation of thyristors, causes of unequal voltage/current sharing in steady state and transient state, and methods to achieve equal sharing.

Explain the working of a three-phase full-wave fully controlled converter with continuous and constant load current.

Determine the RMS output voltage of a single-phase full-wave half-controlled rectifier for given peak voltage and firing angle.

Analyze the operation of a single-phase half-wave rectifier with R and RL loads and compare their performance.

Calculate the average output voltage of a three-phase full-wave fully controlled rectifier for given peak line voltage and firing angle.

Describe the operation of a line-frequency phase-controlled rectifier using SCRs and explain how output voltage is controlled.

What is commutation? Explain external pulse commutation.

Explain the effect of source inductance on the operation of single phase full bridge converter.

Numerically determine the number of series and parallel thyristors required for given total voltage and current ratings with derating, and compare string efficiencies.

Explain the operation of a single-phase fully controlled bridge converter feeding an RL load with output voltage and current waveforms.

Describe the basic circuit, working principle and operation of a single-phase PWM inverter and explain its advantages / performance improvements over traditional inverters.

Explain the basic operation of a single-phase full bridge inverter, including output waveforms and advantages of bridge configuration.

Explain what harmonics are in inverters, why their reduction is important, and the harmonic control/reduction techniques.

Describe the basic structure and operation of a three-phase bridge inverter and its applications in power systems.

Calculate the output current at resonance for a single-phase series resonant inverter given supply voltage, resonant frequency and load resistance.

Explain the principles of on-off control and phase control in AC voltage controllers and how they regulate output voltage.

Discuss the principle of operation of a single-phase transformer taps changer. How does it control the output voltage in power distribution systems?

Explain the basic principle of operation of a cycloconverter and the working of a single-phase to single-phase cycloconverter with typical applications.

Explain the operation of a three-phase to single-phase cycloconverter and discuss its advantages and limitations.

Explain with circuit diagram and waveforms the operation of a bridge-type step-down cycloconverter with resistive load.

Describe the operation of a 1-$\phi$ full-wave AC voltage controller with inductive load and derive the expression for output voltage.

Numerical on single-phase AC voltage controller with on-off control: given supply voltage, resistance, and on/off cycles, determine RMS output voltage and input power factor.

Explain the principle of operation of an SMPS and how it differs from linear power supplies.

Explain the functionality of a buck-boost regulator and how it regulates output voltage when input can be higher or lower than the desired output.

Explain the working principle of a buck regulator and how it steps down input voltage to provide a regulated output.

Explain the operation of a step-up chopper and how it produces an output voltage higher than the input voltage.

Describe the working of a step-up converter and derive the expression for its output voltage.

Describe the flyback SMPS with equivalent circuit and waveforms.