Power Electronics Past Papers important Questions

By: Prof. Fazal Rehman Shamil

Power Electronics Past Papers 1

Paper: Power Electronics

Time Allowed: 3 hours


Total Marks:    70, Passing Marks (35)

Q1.      A half-wave rectifier has a purely resistive load of R. Determine

  • Efficiency
  • Form factor
  • Ripple factor
  • Transformer utilization factor and Peak Inverse Voltage (PIV) of the diode.

Q2.      What do you understand by freewheeling Diode? Discuss its modes of operation with equivalent circuit diagram.

Q3.      Discuss the operation of step-down Chopper with RL load connected. Draw circuit diagram.

Q4.     Mathematically prove that positive regenerative feedback makes it difficult to turn off Thyristor.

Q5.      Draw the circuit arrangement for single phase-semi converter with highly inductive load and find expression for average and rms output voltage.

Q6.       Explain the principal of phase control. Derive relation and draw circuit diagram.

Q7.        Separately excited dc motor is supplied from dc source of 600v to control the speed of mechanical load and field current is maintained constant. The armature resistance and losses are negligible.

  1. If load torque is T1 = 550N.m at 1500 RPM, calculate armature current Ia.
  2. If armature current remains the same in Part (a), and field current is reduced such that motor runs at a speed of 2800. Determine the load torque.


Power Electronics important Questions and Guess Papers 2

Paper: Power Electronics

Time Allowed: 3 hours


Total Marks:    70, Passing Marks (35)

Q.1 True/False.                                                                                                                                      (14)

  • Variations in electronic usage can be achieved with the same power..
  • Power electronics is the technology of efficiently converting electric power.
  • Advanced electronics is applied to the distribution of electrical power such as electricity.
  • The study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles is called electronics
  • The anode-to-gate voltage can be used to turn the PUT on or off…
  • Thyristors are 4-layer semiconductor devices.
  • Base currents are usually small because of the physical construction of the thin and lightly doped base

Q.2      a What is power diode. explain major classificaton of diodes?.                                             (7+7)

What are BJT,s. Explain diferent types and modes of BJT?

Q.3      a. Expain chopper circuit design with types?.                                                                                     (7+7)

b Explain diodes with rlc load circuit?.

Q.4      What are inverters? Explain basic operation of inverter?                                                       (14)

Q.5       Explain Static capacitors? Some application areas where STS are used.                               (14)

Q.6      Define thyristor and explain its basic operation with circuit diagram                                    (14)

Q.7      What is LASCRs?Explain the construction and  working of LASCRs.                                (14)

Q.8      Write short notes on any two of the following                                                                        (7+7)

(a)Gate Turn off Thyristor                  b) Solid State Relay    c) Semi conductor                 


Prof. Fazal Rehman Shamil