Anna University
Department of Electrical & Electronics Engineering
Department : B.E EEE
Semester : V
Year : 3rd yr
Regulation : 2008
Subject Code : EE2301
Subject Name : Power Electronics
Content : EE2301 Power Electronics 16marks (Part B) Important Questions - 2012 Edition.
Unit 1
1. a) Discuss the different modes of operation of thyristor with the help of static VI characteristics. (8)
1. b) Explain the construction of SCR with neat sketch. (8)
2. Draw the switching characteristics of SCR and explain it. (16)
3. Discuss the different modes of operation of TRIAC with the help of VI characteristics. (16)
4. Explain the switching characteristics of TRIAC (16)
5. With the help of neat diagram explain the operation of BJT. (16)
Unit II
1. Discuss the working of 1_ two pulse bridge converter with RLE load using relevant waveforms. (16)
2. A 1_ two pulse bridge converter feeds power to RLE load with R=6_, L= 6mH, E = 60v, ac source voltage is 230v, 50Hz for continuous conduction. Find the average value of load current for firing angle of 50 °. In case one of four SCR‟S gets open circuited. Find the new value of average load current assuming the output current as continuous. (16)
3. a) Explain the operation of 1_ semi converter and derive the expressions for its average and rms output voltage. (8)
3. b) Derive the expressions for harmonic , displacement and power factor of a 1_ full converter from the fundamental principle. (8)
4. Explain the working of 1_ full converter with RL load and derive the expression for the average and rms value. (16)
Unit III
1. Discuss the principle of operation of DC-DC step down chopper with suitable waveforms. Derive the expression for its average dc voltage. (16)
2. A step down dc chopper has input voltage of 230v with 10 ohm load, voltage drop across chopper is 2v, when it is on. For a duty cycle of 0.5. Calculate i) average and rms value of output voltage ii) power delivered to the load. (16)
3. Explain the two quadrant dc chopper operation with RLE load using suitable waveforms. (16)
4. a) Explain time ratio control and current limit control strategies. (8)
b) Explain the resonant switching based SMPS. . (8)
5. Explain any one type of switched mode regulator and derive the expression for it. (16)
Unit IV
1. Explain the operation of single phase half bridge inverter with a neat sketch. (16)
2. The single phase half bridge inverter has resistive load of R=10 ohm and dc input voltage is 220v. Determine rms output voltage, average value, rms current and output power. (16)
3. Explain the operation of single phase full bridge inverter with neat sketch. (16)
4. The single phase full bridge inverter has resistive load of R=2.4 ohm and dc input voltage is 48v. Determine rms output voltage at the fundamental frequency, output power. And the total harmonic distortion. (16)
5. Describe the working of three phase inverter with suitable waveform (16)
Unit V
1. Draw the circuit diagram of 1_ capacitor commutated current source inverter and explain its operation with equivalent circuits for different modes and necessary waveforms.
2. Explain the operation of multistage control of AC voltage controllers with neat diagram
3. .Explain the operation of 1_ AC voltage controller with RL load.
4. Explain the operation of sequence control of AC voltage controller.
5. Explain the operation of 1_ sinusoidal AC voltage controller.
6. For a 1_ voltage controller, feeding a resistive load, draw the waveforms of source voltage, gating signals, output voltage and voltage across the SCR. Describe the working with reference to waveforms drawn.
