B.TechSemester 62024-25Power ElectronicsBEE603

Power Electronics (BEE603) - AKTU Question Paper 2024-25

B.Tech · Semester 6 · Free PDF Download

This is the official AKTU Power Electronics Previous Year Question Paper for B.Tech Semester 6, academic session 2024-25. Published by Dr. A.P.J. Abdul Kalam Technical University (AKTU/UPTU), Lucknow. Free PDF download — no login required.

Course:B.Tech

Semester:Semester 6

Session:2024-25

University:AKTU / UPTU

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Questions Asked in 2024-25

Power Electronics (BEE603) — complete question paper · 70 marks · 3 Hours

Section AAttempt all questions in brief. 02 x 7 = 14

a
Explain power Mosfet
b
Define the term latching current and holding current
c
Explain the difference between freewheeling and feedback diodes
d
Describebriefly the various control strategies used for varyin g duty cycle in choppers
e
What is the difference between AC Voltage controller and Cycloconverter
f
Which mode of operation is prefe rred in a three-phase Voltage Source Inverter (VSI): 120-degree conduction mode or 180-degree conduc tion mode? Justify your answer with appropriate reasons
g
Briefly explain the methods of vo ltage control in a single-phase inverter

Section BAttempt any three of the following: 07 x 3 = 21

a
Draw and explain the V-I characteristics of a thyristor with a s u i t a b l e diagram. Briefly mention the different methods of triggering a thyristor
b
The input voltage V DC of the buck boost converter shown below varies from 32V to 72V. Assume that all comp onents are ideal, inductor curr ent is continuous and output voltage is ripple free. Find the range of duty ration D of the converter for which the magnitude of the steady state ou tput voltage remains constant at 48V
c
Explain the operation of Current Source Inverter (CSI) in de tail with circuit diagram and waveforms
d
Explain the principle of Integ ral Cycle Control in AC Voltage Controller with suitable diagram and mention its output voltage formula. A sing le-phase voltage controller has input voltage of 230V,50Hz and the load of R=15 ohm. For 6 cycles ON and 4 C ycle OFF determine (i) rms output voltage (ii) input power factor (pf)
e
Compare the operation of single-phase half-wave and single-p hase full-wave rectifiers. Draw the circuit diagrams and corresponding output voltage waveforms for the following types of loads: (i) Resistive (R) L oad, (ii) Resistive-Inductive (RL) Load, a nd (iii) Resistive-Inductive wi th Back EMF (RLE) Load. Also, derive the expression for average output voltage

Section CAttempt any one part of the following: 07 x 1 = 07

a
Describe the protection for gate and thyristor in detail wit h suitable diagram. Explain the need and the problem faced inconnecting thyristors in series and parallel
b
Explain commutation and its ty pes with suitable examples. Al so, describe any one class of commutation in detail with a diagram
a
With the help of circuit diagrams,explain the types ofsingle -phase semi converters. Draw the output voltage waveforms for RL load. A single-phase Semi Converter con nected to 230V, 50Hz source is feeding load R=10 ohm in series with a la rge inductance that makes the load current r i p p l e f r e e . F o r f i r i n g a n g l e o f 4 5 d e g r e e . C a l c u l a t e t h e ( i ) average output voltage (Vo) (ii) power factor (pf)
b
Describe the operation of full wave rectifier with output vo ltage waveforms and derive the expression for output voltage. The fully controlled thyristor converter in the figure is fed f rom a single- phase source. When firing angle is 0 degree, the dc output volt age of the converter is 300V. What will be the output voltage for a firing ang le o f 60 degree, assuming continuous conduction
a
What is chopper? Explain the operation of step-up chopper in detail with circuit diagram, output voltage and output current waveforms. D erive an expression for avera ge out put volta ge in terms of in put volta ge and dut y cycle. A step-up chopper is used to feed a load at 400V dc from 250V d c source. The inductor current is continuous. If the ‘OFF’ time of the sw itch is 20µs.Find the switching frequency of the chopper
b
Describe the operating princi ple of buck converter with circ uit diagram, output voltage waveform and its expression.Explain four quadran t chopper (TYPE E) chopper with detailed circuit diagram
a
Describe types of AC Voltage controller with diagram. Explai n the phase control scheme principle of AC V oltage Controller with circuit diagram and waveforms in detail for RL Load for (i) Single phase half wave AC Voltage Controller (ii) Single phase ful l wave AC Voltage Controller. M ention the output rms voltage expression, pha se control expression and ran ge of alpha for controlled output voltage
b
Explain the principle of wor king of types of single phase to single phase cycloconverter with circuit diagrams and output waveforms
a
What are PWM techniques? Explaindifferent types of PWM along withtheir advantages. Explain sinusoidal P WM with suitable diagram in det ail. Define modulation index (MI) and discuss its effect when MI is less th an and greater than 1. (i)-In a single PWM inverters, f ind the pulse width if fifth or der harmonic is eliminated? (ii)- In single PWM if pulse width is equal to 120 degrees for input voltage of 220 V dc Find the rms value of output voltage is?
b
Draw circuit diagram of three phase inverter. With the line and phase voltage expression explain three phases 180-degree six step conduction m ode VSI. Describe switching pattern of thyristors with circuit diagram of conduction of switches, voltage generated in each phase. Also, Draw phase vol tage and line voltage waveforms

Question text is extracted from the official AKTU question paper PDF above. Hindi translations are omitted — every question is printed in English in the original paper. Last verified: 2026-08-23.

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