My Profile
Active Members
TodayLast 7 Days
more...
Awards & Gifts
Online Exams
Fresher Jobs
Our fresher job section is exclusively for fresh graduates! Find jobs for freshers in major Indian
cities including Bangalore, Chennai, Hyderabad, Pune or Kochi
Resources
Find educational articles, blogs, discussion threads and other resources.
Colleges
Find details about any college in India or search for courses.
|
Download Model question papers & previous years question papers
|
Posted Date: 08 Feb 2009 Posted By: ram Member Level: Diamond
|
2008 Jawaharlal Nehru Technological University Electrical and Electronics Engineering Code No: R05 III B.Tech I Semester Regular Examinations, November 2008 POWER ELECTRONICS Question paper
Code No: R05310206 Set No. 3
III B.Tech I Semester Regular Examinations, November 2008
POWER ELECTRONICS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. A 200A thyristor operates in parallel with a 300A thyristor. Their ON state voltage
drops are respectively 1.5V and 1.0V. Calculate the value of the resistance to be
inserted in series with each thyristor so that they share a load of 500A in proportion
to their respective current ratings. [16]
2. (a) Compare mid-point converters and bridge type converters and bring out im-
portant features.
(b) Compare discontinuous and continuous current modes of operation of convert-
ers and bring out salient features. [8+8]
3. A three phase, fully controlled converter is connected to a resistive load. Show that
the average output voltage is given by
Vdc=3p3
2 VmCosa for 0 < a < p/3 and
Vdc = 3p3
2 Vm [1 + Cos(a + p/3)] for p/3 < a < 2p/3 [8+8]
4. The ac voltage controller uses on-off control for heating a resistive load of R = 4
ohms and the input voltage is Vs = 208V, 60Hz. If the desired output power is P0
= 3KW, determine the
(a) duty cycle d
(b) input power factor
(c) sketch waveforms for the duty cycle obtained in (a) [5+6+5]
5. For a single phase mid-point cyclo-converter, explain the operation of the circuit
when fed to R-load with the help of neat circuit diagram and relevant output
waveforms for a = 300 and a = 1200 for f0 = 1/4 fs. [4+8+4]
6. Explain the time ratio control and current limit control strategies used for choppers,
with necessary waveforms and circuit. [8+8]
7. Draw and explain the simple SCR series inverter circuit employing class A type
commutation. With the help of important waveforms. State the limitations of this
inverter. [8+4+4]
8. What are the methods for voltage control within the inverters. Explain in detail
with waveforms.
Return to question paper search
|
|
|
Submit Previous Years University Question Papers and make money from adsense revenue sharing program
Are you preparing for a university examination? Download model question papers
and practise before you write the exam.
|
Advertise Here
|