Gujarat Technological UniversityWinter 2025 examination

GTU 3151106 Power Electronics Winter 2025 Question Paper & PDF

B.E. · EC Engineering · Semester 5 · Subject code 3151106
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Total
70 marks
To pass
23 marks (33%)
Duration
2.5 Hours 10:30 AM – 1:00 PM
Questions
5 with internal choice
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Q.1

14 Marks
(a)
3 marks

Design VI characteristic of SCR. Show and explain the difference between holding current and latching current.

(b)
4 marks
Make the comparison between SCR and TRIAC.
(c)
7 marks

A single phase half wave controlled rectifier is operated from a 240 V, 50 Hz. Load resistance R = 20 Ω. If the average output voltage is 25% of the maximum possible average output voltage, determine:

1)the firing angle
2)rms and average output and SCR currents.

Q.2

14 Marks
(a)
3 marks
Explain the effect of freewheeling diodes in power electronics circuits.
(b)
4 marks
Explain the SCR resistance-capacitance triggering circuit.
(c)
7 marks

Explain the operation of single phase semi controlled bridge converter with resistive and inductive load. Draw the associated waveforms.

(c)
7 marks

A dc chopper circuit connected to 100 V dc source supplies an inductive load having 50 mH in series with resistance of 5 Ω. Freewheeling diodes is placed across the load. The load current varies between the limits of 10-12 A. Determine the time ratio of the chopper.

Q.3

14 Marks
(a)
3 marks

What is the function of Chopper? Explain the working of step-up chopper.

(b)
4 marks

With help of waveform explain the current limit control strategy of chopper.

(c)
7 marks

With help of neat circuit diagram and waveforms, explain the operation of PWM half bridge inverter with resistive load.

(a)
3 marks

What are the applications of chopper? Explain the working of class D chopper.

(b)
4 marks
Compare the step up and step down chopper.
(c)
7 marks

With help of neat circuit diagram and waveforms, explain the operation of single phase current source inverter.

Q.4

14 Marks
(a)
3 marks
What is commutation? Explain self commutation.
(b)
4 marks
Explain the snubber circuits for thyristor.
(c)
7 marks
Explain the basic structure and VI characteristic of IGBT.
(a)
3 marks

What is the function of an inverter? List out various applications of an inverter.

(b)
4 marks
Explain two transistor analogy of SCR.
(c)
7 marks

Draw and explain the structure of power MOSFET. Explain principle and operation and V-I characteristics of power MOSFET.

Q.5

14 Marks
(a)
3 marks
Compare Power supply and SMPS.
(b)
4 marks
Explain the working of Fly back SMPS.
(c)
7 marks
Write short note on UPS.
(a)
3 marks
Compare EMI and EMC.
(b)
4 marks
Explain the working of DC chopper drive.
(c)
7 marks
Write short note on P M Stepper Motor drives.

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About this paper

Official Gujarat Technological University (GTU) examination paper for Power Electronics (Winter 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.

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