Q.1
14 Marks(a)
Explain briefly the concept of power electronics.
(b)
Define and compare holding and latching currents of SCR.
(c)
What is commutation? With help of circuit and wave form explain self commutation by an LC circuit.
Gujarat Technological UniversitySummer 2025 examination
GTU 3151106 Power Electronics Summer 2025 Question Paper & PDF
B.E. · EC Engineering · Semester 5 · Subject code 3151106
- Total
- 70 marks
- To pass
- 23 marks (33%)
- Duration
- 2.5 Hours 2:30 PM – 5:00 PM
- Questions
- 5 with internal choice
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Q.2
14 Marks(a)
Compare simple rectifier and controlled rectifier.
(b)
With help of neat diagram and associated waveform, explain the operation of half wave RC triggering circuit.
(c)
A complementary commutation circuits operate from DC supply of 120 V and use R1 = R2 = 10 Ω, commutating capacitor C = 10 μF. Calculate circuit turn off time and peak thyristor current.
OR
(c)
A single phase full converter is supplied from 230 V, 50 Hz supply. The load current is continuous and ripples free. If the average current is 150 A and source inductance is 0.1 mH determine the overlap angle at
i)α
= 100
ii)α = 300
iii)α = 600
Q.3
14 Marks(a)
Write the classification of DC Chopper.
(b)
With help of circuit diagram explain the working of class E chopper.
(c)
Explain the various voltage control methods of single phase inverter.
OR
(a)
Enumerate the merits and demerits of load commutated chopper.
(b)
With help of circuit diagram explain the working of Jones chopper.
(c)
With help of neat circuit diagram and waveforms, explain the operation of single phase voltage source inverter.
Q.4
14 Marks(a)
Explain the power integrated circuits.
(b)
Compare DIAC and TRIAC.
(c)
Which are the conditions to make SCR on? Explain the full wave RC triggering circuit in detail.
OR
(a)
Explain the effect of freewheeling diode.
(b)
What are advantages of IGBT? Explain the basic structure of IGBT.
(c)
With help of neat circuit diagram and associated waveform explain the operation of single phase full wave controlled rectifier with resistive and inductive load.
Q.5
14 Marks(a)
Explain the discontinuous mode of isolated fly back SMPS.
(b)
Explain MOS controlled thyristor.
(c)
With help of block diagram explain the operation of on line uninterrupted power supply. Write the detail specifications of on line UPS.
OR
(a)
What is meant by EMI and EMC?
(b)
Explain the capacity and efficiency of batteries used in UPS.
(c)
Explain the construction, working and applications of separately excited DC motor drive.
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About this paper
Official Gujarat Technological University (GTU) examination paper for Power Electronics (Summer 2025, B.E. · EC Engineering, Sem 5). Features complete 70-mark regular & remedial examination pattern, official marking distribution across all 5 questions, and direct 1-click official PDF download.
Transcribed for student exam preparation from Gujarat Technological University official examination archives. Questions, syllabus guidelines, and curriculum marking schemes remain the intellectual property of Gujarat Technological University.