Power Electronics-1 - May 2016
Electronics Engineering (Semester 6)
TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1(a) Draw and explain dynamic turn on characteristics of SCR.(5 marks) 1(b) What is the need of communication. Explain the any one method of forced communication.(5 marks) 1(c) Define and explain performance parameters of controlled rectifier.(5 marks) 1(d) Draw and explain boost converter. Derive the relation for output load voltage.(5 marks) 2(a) Draw and explain semi-converter with the help of circuit diagram and waveforms.(10 marks) 2(b) Draw and explain Buck-Boost converter with the help of circuit diagram and waveforms Derive the relation for load voltage.(10 marks) 3(a) Explain the working of three phase bridge inverter in 120° conduction mode with resistive load. Draw waveforms.(10 marks) 3(b) Draw the load voltage waveform for the circuit given below.
(i) Firing angle
(ii) RMS and Average output current
(iii) RMS and average thyristor current(10 marks) 4(b) Explain in brief single phase cyclo-converter with circuit diagram and waveforms.(5 marks) 4(c) Explain the need of neutrilisation of harmonics of inverters.(5 marks) 5(a) Explain the working of AC full wave control circuit using DIAC-TRIAC. Draw waveforms accross load and TRFAC for α = 60°. Derive relation for RMS load voltage.(10 marks) 5(b) Explain the multiple pulse width modulation in inverters. Explain the neutrilisation of harmonics.(10 marks) 6(a) Single phase full bridge inverter has a resistive load of R = 3Ω and the dc input voltage Edc = 50V. Compute
(i) The average output power Po
(ii) The average and peak current of each thyristor.(10 marks) 6(b) Draw and explain switching cha. Of GTO(5 marks) 6(c) Draw and explain snubber circuit.(5 marks)