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Btee 604 C 18

This document is an exam for a course on line commutated and active PWM rectifiers. It contains instructions for the exam and questions in three sections - Section A with 10 short answer questions, Section B with 4 long answer questions, and Section C with 2 long answer questions. The questions cover topics like types of rectifiers, thyristor converter operation, voltage and current ripple factors, rectifier circuits and operation, PWM rectifiers advantages, and derivations for rectifier output voltages.

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Babbu Dogra
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120 views2 pages

Btee 604 C 18

This document is an exam for a course on line commutated and active PWM rectifiers. It contains instructions for the exam and questions in three sections - Section A with 10 short answer questions, Section B with 4 long answer questions, and Section C with 2 long answer questions. The questions cover topics like types of rectifiers, thyristor converter operation, voltage and current ripple factors, rectifier circuits and operation, PWM rectifiers advantages, and derivations for rectifier output voltages.

Uploaded by

Babbu Dogra
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Roll No. Total No.

of Pages : 02
Total No. of Questions : 09
B.Tech. (Electrical and Electronics Engineering) (Sem.–6)
LINE COMMUTATED AND ACTIVE PWM RECTIFIERS
Subject Code : BTEE-604C-18
M.Code : 79952
Date of Examination : 09-07-22
Time : 3 Hrs. Max. Marks : 60

INSTRUCTIONS TO CANDIDATES :
1. SECTION-A is COMPULSORY consisting of TEN questions carrying T WO marks
each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3. SECTION-C contains T HREE questions carrying T EN marks each and students
have to attempt any T WO questions.

SECTION-A

1. Write briefly :

a) Discuss the types of rectifiers.

b) What do you understand by continuous current operation of thyristor converter?

c) Define the term voltage ripple factor and current ripple factor.

d) What is the function of free-wheeling diode in controlled rectifier?

e) Define pulse number of converter response.

f) Define the term delay angle and margin angle.

g) What is the condition for rectification in single-phase fully controlled converter.

h) What do you understand by line-commutated converters?

i) A power supply A delivers 20 V dc with a ripple of 0.5 V r.m.s. while the power
supply B delivers 25 V dc with a ripple of 1 mV r.m.s. Which is better power supply?

j) What is the ripple factor for half-wave rectifier?

1 | M-79952 (S2)-874
SECTION-B

2. Draw the phasor diagram and explain the operation of single-phase AC-DC active PWM
rectifier under lagging, leading and unity power factor conditions.

3. Explain the continuous and discontinuous conduction modes of thyristor rectifiers.

4. Draw the circuit diagram of twelve pulse rectifier and explain its operation with the help
of suitable waveforms.

5. What are the advantages of active PWM rectifiers over diode bridge rectifiers?

6. A single-phase thyristor converter is shown in figure below with source inductance Ls


then

Fig.1

a) Derive the expression for the commutation angle u, and

b) Calculate it if Vs (rms) = l50 V, Ls = 3 mH, Id = 8.5 A, and  = 35º Frequency f


= 50 Hz.

SECTION-C

7. Derive the expression for average(dc) output voltage of three-phase line-commutated


rectifier with L and LC filter and draw the waveforms.

8. Explain the operation of three-phase full-bridge thyristor converter with suitable diagram
and waveforms.

9. Describe the effect of source inductance on the performance of a single-phase full


converter indicating clearly the conduction of various thyristors during one cycle. Derive
the expression for its output voltage.

NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.

2 | M-79952 (S2)-874

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